WO2014002145A1

WO2014002145A1 - Air conditioner and control method therefor

Info

Publication number: WO2014002145A1
Application number: PCT/JP2012/004235
Authority: WO
Inventors: 悟梁池; 加藤　央平
Original assignee: 三菱電機株式会社
Priority date: 2012-06-29
Filing date: 2012-06-29
Publication date: 2014-01-03
Also published as: GB201421070D0; JPWO2014002145A1; GB2517346B; GB2517346A; US20150153079A1

Abstract

When operation commences in the air conditioner (100) of the present invention, an operation determination means (21) determines whether said operation is cooling operation or heating operation. When it is determined that the operation is not cooling operation, cooling is not performed at a discharge gas cooling device (2). When it is determined that the operation is cooling operation, cooling is performed at the discharge gas cooling device (2).

Description

Air conditioning apparatus and control method thereof

The present invention relates to an air conditioner and a control method thereof, and more particularly, to an air conditioner that performs a cooling operation and a heating operation and a control method thereof.

In the air conditioner, there are reciprocal type, screw type, scroll type, rotary type and the like structures for the compressor that generates the driving force for circulating the refrigerant. In any system, it is common to enclose refrigeration oil for lubrication of the sliding portion. In order to ensure the reliability of the compressor, it is necessary to continue to supply the compressor with a predetermined concentration and a predetermined amount. In particular, even under conditions where the oil concentration is most likely to be thinned (for example, during startup), the refrigerating machine oil is more than the required amount during stable operation so as to continue to supply a predetermined amount and a predetermined amount to the compressor. May be enclosed.

¡Encapsulating more refrigeration oil than necessary for stable operation increases the oil level in the compressor, making it easier to discharge the refrigeration oil in the compressor. And there exists a problem that the pressure loss in piping increases with the increase in the circulation amount (oil circulation rate) of refrigeration oil with a high viscosity in a refrigerant | coolant, and the COP capability is reduced.

In order to solve this problem, an oil separator is installed at the discharge part of the compressor, the refrigeration oil and the refrigerant are separated by this oil separator, and the separated refrigeration oil is returned to the compressor, so that A method for reducing the concentration of oil circulating in the water has been proposed (see, for example, Patent Documents 1 and 2). Further, it has been disclosed that the separation efficiency is improved by cooling the compressor discharge gas to about the condensation temperature of the refrigerant and separating the gaseous refrigerating machine oil (see, for example, Patent Document 3).

JP 62-80473 A Japanese Utility Model Publication No. 02-131171 JP-A-62-98170

By the way, in recent years, improvement of COP (Coefficient of Performance) in air conditioners is desired. As shown in Patent Documents 1-3, it is considered that the COP is improved by separating the refrigerant and oil and lowering the oil circulation rate of the refrigerant. However, when attention is paid only to the oil circulation rate, there is a problem that the COP may be deteriorated.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide an air conditioner capable of improving COP both during cooling operation and during heating operation, and a control method therefor. It is what.

An air conditioner according to the present invention has a refrigerant circuit in which a compressor, a discharge gas cooling device, an oil separator, a four-way valve, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger are connected in an annular shape. The air conditioner is capable of cooling operation and heating operation by switching the flow path by the operation determining means for determining whether the operation state is the cooling operation or the heating operation, and the operation determining means is the cooling operation. If it is determined that there is, the discharge gas cooling device is controlled so as to cool the discharge gas discharged from the compressor, and if it is determined that the heating operation is being performed, the discharge gas cooling device is controlled so as not to cool the discharge gas. And a heat dissipation control means.

According to the oil separator and the air conditioner according to the present invention, during cooling operation, the discharge gas is cooled by the discharge gas cooling device to promote separation in the oil separator to lower the oil circulation rate and improve the COP. During the heating operation, cooling of the discharge gas can be stopped to suppress the heat radiation in the discharge gas cooling device, and the reduction in COP can be reduced.

It is a schematic diagram which shows the structure of Embodiment 1 of the air conditioning apparatus which concerns on this invention. FIG. 2 is a ph diagram showing an operation state during cooling operation of the air conditioner of FIG. 1. FIG. 2 is a ph diagram showing an operation state during heating operation of the air conditioner of FIG. 1. It is a graph which shows the relationship between the pressure loss of a compressor suction | inhalation from the evaporator exit at the time of air_conditionaing | cooling operation of the air conditioning apparatus of FIG. 1, and COP. It is a graph which shows the relationship between the oil circulation rate and COP ratio in the air conditioning apparatus of FIG. It is a graph which shows the relationship between the emitted-heat amount and COP ratio in the discharge gas cooling device in the heating operation of the air conditioning apparatus of FIG. It is a flowchart which shows Embodiment 1 of the control method of the air conditioning apparatus which concerns on this invention. It is a flowchart which shows Embodiment 2 of the control method of the air conditioning apparatus which concerns on this invention. It is a schematic diagram which shows the structure of Embodiment 3 of the air conditioning apparatus which concerns on this invention. It is a schematic diagram which shows the structure of Embodiment 4 of the air conditioning apparatus which concerns on this invention. It is a schematic diagram which shows the structure of Embodiment 5 of the air conditioning apparatus which concerns on this invention.

Embodiment 1. FIG.
Hereinafter, preferred embodiments of the air-conditioning apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing Embodiment 1 of an air-conditioning apparatus of the present invention. An air conditioner 100 in FIG. 1 performs both a cooling operation and a heating operation, and includes a compressor 1, a discharge gas cooling device 2, an oil separator 3, a four-way valve 4 as a flow path switch, an indoor heat. It has a refrigerant circuit in which the exchanger 6, the expansion valve 8, and the outdoor heat exchanger 9 are annularly connected by a refrigerant circuit. Among these, the compressor 1, the discharge gas cooling device 2, the oil separator 3, the four-way valve 4, the expansion valve 8, and the outdoor heat exchanger 9 constitute an outdoor unit 10, and the indoor heat exchanger 6 is an indoor unit 11. Is configured. The outdoor unit 10 and the indoor unit 11 are connected by a gas side extension pipe 5 and a refrigerant liquid side extension pipe 7, and the refrigerant is connected to the outdoor unit 10 and the indoor unit via the gas side extension pipe 5 and the refrigerant liquid side extension pipe 7. Cycle between 11 and 11.

The compressor 1 uses the refrigerant sent from the four-way valve 4 as a high-temperature and high-pressure discharge gas. Various methods can be used as the compressor 1. As the compressor 1 that generates the driving force for circulating the refrigerant, various techniques such as a reciprocating type, a screw type, a scroll type, and a rotary type can be used.

The discharge gas cooling device 2 cools the discharge gas discharged from the compressor 1 and includes a pump 12, a radiator 13, and a heat exchanger 14. The pump 12, the radiator 13 and the heat exchanger 14 constitute a circulation circuit for circulating water, brine and the like. The pump 12 circulates circulating materials such as water and brine between the radiator 13 and the heat exchanger 14. The radiator 13 cools (heatsinks) water or brine circulating in the circulation circuit. The heat exchanger 14 performs heat exchange between the discharge gas and water, brine, or the like flowing through the circulation circuit. The heat exchanger 14 includes, for example, a refrigerant flow path through which the discharge gas from the compressor 1 flows and a cooling flow path 14a through which the circulating material flows. The heat flow of the discharge gas flowing through the refrigerant flow path is reduced by the cooling flow path 14a. The discharge gas is cooled by taking away the circulating material flowing through. In addition, as this heat exchanger 14, various well-known techniques, such as what is called a shell and tube type, a shell and coil type, a double pipe type, can be used.

Here, when the pump 12 is operated, water, brine, and the like circulate in the circulation circuit, and heat exchange is performed between the water and the discharge gas in the heat exchanger 14. The heat-exchanged water is radiated (cooled) by the radiator 13. As a result, the discharge gas is cooled (heat radiation). On the other hand, when the pump 12 is stopped, the circulation of water and the like in the circulation circuit is stopped, heat exchange in the heat exchanger 14 is not performed, and the discharge gas is not cooled. The operation of the pump 12 is controlled by the heat radiation control means 22, and the heat radiation control means 22 controls whether the discharge gas is cooled by the discharge gas cooling device 2 by controlling ON / OFF of the pump 12. .

The oil separator 3 separates oil from the discharged gas and returns the separated oil to the compressor 1. For example, the oil separator 3 compresses the separated oil provided in the bottom portion, the inflow piping into which the gas discharged from the discharge gas cooling device 2 flows, the discharge piping for discharging the refrigerant gas to the four-way valve 4, and the bottom. It has a structure provided with a pipe returning to the machine 1. When gas flows into the hollow container from the inflow pipe, the oil adheres to the surface of the hollow container and flows down toward the bottom surface of the hollow container, and the oil on the bottom surface is returned to the compressor 1 through the pipe. On the other hand, the refrigerant gas is discharged from the discharge pipe toward the four-way valve 4.

Here, the lower the temperature of the refrigerant gas discharged from the compressor 1, the more oil and refrigerant can be separated in the oil separator 3. That is, when the discharge gas cooling device 2 cools the discharge gas before the discharge gas enters the oil separator 3 from the compressor 1, the temperature of the oil contained in the discharge gas also decreases. When the oil is cooled, the viscosity and density are increased, and the oil is easily attached and trapped on the hollow container surface of the oil separator 3. As a result, when the discharge gas cooling device 2 cools the discharge gas, separation of the oil and the refrigerant in the oil separator 3 can be promoted.

The four-way valve 4 switches the direction in which the refrigerant flows according to the operation mode of the indoor unit 11. Specifically, during the cooling operation, the four-way valve 4 is controlled so that the discharge gas flows from the oil separator 3 to the outdoor heat exchanger 9. On the other hand, the switching of the four-way valve 4 is controlled so that the refrigerant flows from the oil separator 3 toward the indoor heat exchanger 6 during the heating operation. The expansion valve (throttle valve) 8 throttles the refrigerant flow path in order to adjust the amount of refrigerant flowing into the evaporator.

The indoor heat exchanger 6 exchanges heat between the indoor air and the refrigerant, and the outdoor heat exchanger 9 exchanges heat between the outdoor air and the refrigerant. Specifically, during the cooling operation, the indoor heat exchanger 6 serves as an evaporator, and the outdoor heat exchanger 9 serves as a condenser. In the indoor heat exchanger 6, the refrigerant absorbs heat from the indoor air and outputs cold air, and in the outdoor heat exchanger 9, the refrigerant is radiated by the outdoor air and outputs hot air. On the other hand, during the heating operation, the indoor heat exchanger 6 becomes a condenser and the outdoor heat exchanger 9 becomes an evaporator. Then, in the indoor heat exchanger 6, the refrigerant radiates heat to the indoor air and outputs hot air, and in the outdoor heat exchanger 9, the refrigerant absorbs heat into the outdoor air and outputs cold air.

The operation of the outdoor unit 10 described above is controlled by the controller 20. In particular, the controller 20 is provided with an operation determination unit 21 and a heat dissipation control unit 22 in order to switch the operation of the discharge gas cooling device 2 between the cooling operation and the heating operation. The operation determination means 21 determines whether the operation state is a cooling operation or a heating operation. For example, the operation determination means 21 determines the operation state based on the switching state of the four-way valve 4.

The heat dissipation control means 22 controls cooling in the discharge gas cooling device 2 based on the determination in the operation determination means 21. Specifically, the heat radiation control means 22 controls the heat radiation of the refrigerant in the heat exchanger 14 by controlling ON / OFF of the operation of the pump 12. When it is determined that the operation determination unit 21 is in the cooling operation, the heat radiation control unit 22 controls the pump 12 so that the cooling in the heat exchanger 14 is performed. When the operation determination unit 21 determines that the heating operation is performed, the heat radiation control unit 22 controls the pump 12 to stop and not cool.

FIG. 2 is a graph showing an example of a ph diagram during the cooling operation of the air conditioner 100, and an example of the operation of the air conditioner 100 during the cooling operation will be described with reference to FIGS. First, the refrigerant is sucked into the compressor 1 in a low-pressure gas state (state a), and the low-pressure gas is compressed by the compressor 1 to become a high-temperature and high-pressure gas (state b). The discharge gas from the compressor 1 is cooled by the discharge gas cooling device 2 (state c), and is separated into refrigerant and refrigerating machine oil in the oil separator 3. The refrigerating machine oil separated by the oil separator 3 returns to the suction of the compressor 1. On the other hand, the refrigerant is condensed in the outdoor heat exchanger 9 to become a high-pressure liquid refrigerant (state d). The liquid refrigerant becomes a low-pressure two-phase refrigerant at the expansion valve 8 (state e), passes through the refrigerant liquid-side extension pipe 7, and becomes low-pressure gas at the indoor heat exchanger 6 (state f). Thereafter, the low pressure gas passes through the gas side extension pipe 5 and returns to the compressor 1 (state a).

FIG. 3 is a graph showing an example of a ph diagram during the heating operation of the air conditioner 100, and an example of the operation of the air conditioner 100 during the heating operation will be described with reference to FIGS. First, it is sucked into the compressor 1 in a low-pressure gas state (state a10), and is compressed by the compressor 1 into a high-temperature and high-pressure gas (state b10). The discharge gas cooling device 2 does not radiate heat, and the high-temperature and high-pressure gas is separated by the oil separator 3 into refrigerant and refrigerating machine oil. The refrigerating machine oil separated by the oil separator 3 returns to the suction of the compressor 1. On the other hand, the refrigerant passes through the gas side extension pipe 5 and is condensed in the indoor heat exchanger 6 to become a high-pressure liquid refrigerant (state d10). This high-pressure liquid refrigerant becomes a low-pressure two-phase refrigerant at the expansion valve 8 (state e10). Then, the refrigerant passes through the refrigerant liquid side extension pipe 7, enters a low-pressure gas state in the outdoor heat exchanger 9 (state f10), and returns to the compressor 1 (state a10).

As shown in FIG. 2, the cooling by the discharge gas cooling device 2 during the cooling operation promotes the separation of the refrigerating machine oil from the refrigerant, so that the pressure loss of the compressor suction from the evaporator outlet is reduced during the cooling operation. In addition, the COP can be improved by the heat release of the refrigerant in the discharge gas cooling device 2. On the other hand, as shown in FIG. 3, the cooling by the discharge gas cooling device 2 is not performed during the heating operation, so that the reduction of the enthalpy difference in the outdoor heat exchanger (condenser) can be prevented and the COP reduction can be prevented.

FIG. 4 is a graph showing the relationship between pressure loss and COP when the compressor is sucked from the evaporator outlet. The horizontal axis of FIG. 4 is (evaporator outlet pressure) / (compressor inlet pressure) × 100, indicating 100% when the pressure loss is 0, and the higher the pressure loss, the higher the pressure loss. Indicates that the ratio (%) increases (the longer the distance). The vertical axis represents the COP ratio when the pressure loss is 0 (the horizontal axis is 100%). In FIG. 4, it can be seen that the COP decreases as the pressure loss from the evaporator outlet to the compressor suction increases.

As described above, during the cooling operation, the indoor heat exchanger 6 serves as an evaporator, and the outdoor heat exchanger 9 serves as a condenser. On the other hand, during the heating operation, the indoor heat exchanger 6 becomes a condenser and the outdoor heat exchanger 9 becomes an evaporator. That is, the distance from the evaporator outlet to the compressor 1 means the distance from the indoor heat exchanger 6 of the indoor unit 11 to the compressor 1 of the outdoor unit 10 during the cooling operation, and the outdoor unit 10 outdoor during the heating operation. It means the distance from the heat exchanger 9 to the compressor 1 of the outdoor unit 10.

Since the long gas side extension pipe 5 is used to connect the outdoor unit 10 and the indoor unit 11 during the cooling operation, the compressor is discharged from the outlet of the evaporator (indoor heat exchanger 6), which is a large COP lowering factor for the refrigeration cycle. The pressure loss up to the inlet of 1 increases. On the other hand, during the heating operation, the outdoor heat exchanger 9 serves as an evaporator, but since the constituent devices are the same in the outdoor unit 10, the piping connecting the outdoor heat exchanger 9 and the compressor 1 is the gas side described above. It is significantly shorter than the extension pipe 5. That is, there is no long pipe that causes a large pressure loss such as the gas side extension pipe 5 between the outlet of the evaporator and the suction of the compressor as in the cooling operation. Therefore, during heating operation, the pressure loss reduction from the outlet of the evaporator (outdoor heat exchanger 9) to the suction port of the compressor 1 is minimized.

FIG. 5 is a graph showing the relationship between the oil circulation rate (= {oil flow rate / (refrigerant flow rate + oil flow rate)} × 100) and the COP ratio. FIG. 5 shows that the higher the oil circulation rate, the lower the COP ratio. That is, it means that the more the oil separator 3 separates the refrigerating machine oil from the discharge gas of the compressor 1, the pressure loss in the gas side extension pipe 5 is improved and the COP is improved. In other words, it can be said that if the discharge gas is cooled in the discharge gas cooling device 2 and oil separation in the oil separator 3 is promoted to lower the oil circulation rate, the COP can be improved regardless of the operation state. However, it has been found that if the cooling by the discharge gas cooling device 2 is performed during the heating operation, the COP is lowered.

FIG. 6 is a graph showing the relationship between the heat release amount and COP in the discharge gas cooling device 2 during heating operation. In addition, the horizontal axis of FIG. 6 is the ratio of the heat release amount in the discharge gas cooling device 2 to the heat release amount of the entire refrigerant during the heating operation (heat release amount in the discharge gas cooling device 2 / total heat release amount) × 100. Indicates. The vertical axis represents the COP ratio based on the COP when the heat release amount in the discharge gas cooling device 2 is zero. As shown in FIG. 6, the COP ratio decreases as the heat dissipation amount increases.

That is, cooling the discharge gas of the compressor 1 in the discharge gas cooling device 2 during the heating operation means that the amount of heat that is originally desired for heating the room by the indoor heat exchanger 6 is on the upstream side of the indoor heat exchanger 6. It means that the discharged gas cooling device 2 radiates heat. In order to supplement the capacity required for heating, it is necessary to increase the speed of the compressor 1, so that cooling by the discharge gas cooling device 2 becomes a factor of lowering the COP ratio.

Further, as described above, even if the separation efficiency in the oil separator 3 is increased, the pressure loss from the outlet of the original outdoor heat exchanger (evaporator) 9 to the inlet of the compressor 1 is small. COP improvement efficiency is small (see FIG. 4). In other words, the COP deterioration due to the increase in the compressor frequency is larger than the COP improvement associated with the decrease in the oil circulation rate due to the cooling of the discharge gas, so that the heat dissipation performed by the discharge gas cooling device 2 is compensated. It becomes a factor of COP fall.

Therefore, the heat radiation control means 22 performs control so that the discharge gas cooling device 2 performs cooling during the cooling operation. Thereby, COP can be improved by performing heat radiation with the discharge gas cooling device 2, reducing the pressure loss of the compressor suction | inhalation from an evaporator exit at the time of air_conditionaing | cooling operation. On the other hand, the heat radiation control means 22 performs control so that the discharge gas cooling device 2 is not cooled during the heating operation. Thereby, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) can be prevented and COP reduction can be prevented.

That is, for example, an air conditioner that always performs cooling operation installs a heat exchanger inside a refrigerator or the like, installs an outdoor unit outside the warehouse, and connects the heat exchanger and outdoor unit inside the warehouse below the piping, It has a configuration connected by extension piping. In such an air conditioner, since the extension pipe is long, the pressure loss of the compressor suction from the evaporator outlet that greatly affects the COP of the air conditioner is large. Therefore, the COP improvement effect by the pressure loss improvement of the compressor suction from the evaporator outlet due to the improvement of the separation efficiency is great. Furthermore, COP can be improved by reducing the condensation temperature due to cooling of the compressor discharge gas.

On the other hand, in the air conditioning apparatus 100 that performs cooling operation and heating operation of an air conditioner or the like, there is a problem that COP is lowered during the heating operation. Also in the air conditioner 100 that performs cooling and heating such as an air conditioner, the indoor heat exchanger 6 is installed indoors, the outdoor unit 10 is installed outside, and the indoor heat exchanger 6 and the outdoor are connected by the

extension pipes

5 and 7. The structure which connects the machine 10 is the same as that of a refrigerator. Accordingly, the cooling temperature is reduced by cooling the gas discharged from the compressor during the cooling operation, and the compressor suction is connected from the evaporator outlet by a long extension pipe, so that the COP improvement due to the lower oil circulation rate is great.

However, since the indoor heat exchanger becomes a condenser and the outdoor heat exchanger becomes an evaporator during heating operation, cooling the discharge gas of the compressor 1 is originally intended to be used as a heating capacity in the indoor heat exchanger 6. It means taking away heat. Further, the pipe connecting the evaporator outlet and the suction port of the compressor 1 is short because the evaporator and the compressor 1 are connected in the same outdoor unit, and the COP improvement effect due to a decrease in the oil circulation rate is also very high. small. For this reason, there exists a problem that COP will fall if the discharge gas of a compressor is cooled at the time of heating operation.

Therefore, in the air conditioner 100, the discharge gas cooling device 2 performs cooling during the cooling operation. Thereby, during cooling operation, COP can be improved by reducing heat loss from the outlet of the evaporator to the suction of the compressor, and by dissipating heat with the discharge gas cooling device 2. On the other hand, cooling (heat radiation) is not performed by the discharge gas cooling device 2 during the heating operation. Thereby, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) can be prevented and COP reduction can be prevented.

FIG. 7 is a flowchart showing a preferred embodiment of the control method for the air conditioner of the present invention. The control method for the air conditioner 100 will be described with reference to FIGS. 1 and 7. First, when the operation is started (step ST1), the operation determination means 21 determines whether the operation is a cooling operation or a heating operation (step ST2). When it is determined that the heating operation is performed instead of the cooling operation, the discharge gas cooling device 2 does not perform cooling (step ST3). On the other hand, when it is determined that the cooling operation is being performed, the discharge gas cooling device 2 cools the discharge gas by the action of the heat radiation control means 22.

Thereby, during cooling operation, the pressure loss due to the suction of the compressor from the outlet of the evaporator can be reduced, and the discharge gas cooling device 2 can dissipate the refrigerant to improve the COP. On the other hand, since cooling (heat radiation) is not performed in the discharge gas cooling device 2 during heating operation, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) 9 can be prevented, and COP reduction can be prevented.

Embodiment 2. FIG.
FIG. 8 is a schematic diagram showing an air conditioner according to a second embodiment of the present invention. The air conditioner will be described with reference to FIGS. 1 and 8. In the control method for the air conditioner in FIG. 8, parts having the same steps as those in the control method for the air conditioner in FIG. The control method of the air conditioner of FIG. 8 is different from that of the air conditioner 100 of FIG. 1 in that the discharge gas cooling device 2 controls the discharge gas during the cooling operation and when the operation frequency f is equal to or higher than the set operation frequency fref. This is the point of cooling.

Specifically, the heat dissipation control means 22 in FIG. 1 has a function of determining whether or not the operating frequency f of the compressor 1 is equal to or higher than a preset operating frequency fref. The heat release control means 22 controls the discharge gas cooling device 2 to cool the discharge gas when the compressor 1 is operating at an operation frequency equal to or higher than the set operation frequency fref. On the other hand, when the compressor 1 is operating at an operation frequency lower than the set operation frequency fref even in the cooling operation, control is performed so that the discharge gas cooling device 2 does not cool the discharge gas. The set operation frequency fref is determined in advance in consideration of the effect of reducing the pressure loss due to the reduction of the oil circulation rate and the influence of the input increase of the pump of the discharge gas cooling device 2.

Thereby, it is possible to prevent the influence of COP deterioration caused by driving the power of the pump 12 of the discharge gas cooling device 2 from increasing. That is, the operation frequency f of the compressor 1 and the oil circulation rate are in a proportional relationship, and the higher the operation frequency, the greater the oil circulation rate. For this reason, when the operating frequency f of the compressor 1 is low, the COP improvement effect obtained by reducing the oil circulation rate using the power of the pump of the discharge gas cooling device 2 is the pump of the discharge gas cooling device 2 and the like. There is a possibility that it becomes smaller than the influence of the deterioration of COP by the power of. Therefore, by performing the threshold processing of the operating frequency f, it is possible to prevent the influence of COP deterioration due to the power of the pump of the discharge gas cooling device 2 from increasing.

In addition, when the cooling operation is performed at the operation frequency f around the set operation frequency fref, the presence or absence of cooling in the discharge gas cooling device 2 is switched in a short time, and the operation may not be stable. Therefore, when the operating frequency becomes equal to or higher than the set operating frequency even though the duration that is lower than the predetermined operating frequency is within the predetermined time, the heat radiation control means 22 does not immediately cool the discharge gas. Alternatively, the discharge gas cooling device 2 may be controlled. Thereafter, when the operation time at the set operation frequency fref or more continues for a set time set in advance, the heat radiation control means 22 may be controlled to start cooling the discharge gas by the discharge gas cooling device 2. Alternatively, the cooling operation in the discharge gas cooling device 2 may not be switched immediately at the set operation frequency fref due to the increase / decrease rate of the operation frequency f.

Embodiment 3 FIG.
FIG. 9 is a schematic diagram showing Embodiment 3 of the air conditioner of the present invention. The air conditioner 200 will be described with reference to FIG. In addition, in the air conditioning apparatus 200 of FIG. 9, the site | part which has the same structure as the air conditioning apparatus 100 of FIG. 1 attaches | subjects the same code | symbol, and abbreviate | omits the description. The air conditioning apparatus 200 in FIG. 9 is different from the air conditioning apparatus 100 in FIG. 1 in the configuration of the discharge gas cooling apparatus.

9 includes a first three-way valve 215 and a heat exchanger 14, and a circulation circuit is formed by the first three-way valve 215 and the heat exchanger 14. The first three-way valve 215 is connected to the suction side of the compressor 1, the four-way valve 4, and the heat exchanger 14. Further, on the downstream side of the three-way valve 215, the piping is branched so that the suction gas flows into both the compressor 1 and the cooling flow path 14a of the heat exchanger 14. Therefore, the discharge gas cooling device 202 has a configuration capable of cooling the discharge gas flowing through the refrigerant circuit by circulating the suction gas before compression in the cooling flow path 14a of the heat exchanger 14.

Here, the heat dissipation control means 222 performs switching control by the first three-way valve 215 as to whether or not the intake gas before entering the compressor 1 is circulated through the cooling flow path 14a of the heat exchanger 14. Specifically, the heat dissipation control means 222 switches and controls the three-way valve 215 so that the intake gas flows into the heat exchanger 14 during the cooling operation. Then, heat exchange is performed between the suction gas and the discharge gas from the compressor 1 in the heat exchanger 14 to cool the discharge gas. On the other hand, the heat radiation control means 222 switches and controls the three-way valve so that the refrigerant before compression does not flow to the heat exchanger 14 during the heating operation. Then, since the suction gas does not flow in the heat exchanger 14, the discharge gas from the compressor 1 is not cooled.

Even in the third embodiment described above, the COP can be improved by reducing the pressure loss of the compressor suction from the outlet of the evaporator during the cooling operation and radiating the refrigerant in the discharge gas cooling device 202. . On the other hand, since the cooling by the discharge gas cooling device 202 is not performed during the heating operation, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) 9 can be prevented and COP reduction can be prevented. Furthermore, when performing heat dissipation during cooling operation, the refrigerant can be heated in the heat exchanger 14 before the refrigerant is sucked into the compressor 1, and the liquid refrigerant returns to the compressor 1 and damages the compressor 1. Can be prevented.

Embodiment 4 FIG.
FIG. 10 is a schematic view showing Embodiment 4 of the air conditioner of the present invention, and the air conditioner 300 will be described with reference to FIG. In addition, in the air conditioning apparatus 300 of FIG. 10, the same code | symbol is attached | subjected to the site | part which has the same structure as the air conditioning apparatus 100 of FIG. 1, and the description is abbreviate | omitted. The air conditioning apparatus 300 in FIG. 10 is different from the air conditioning apparatus 100 in FIG.

The discharge gas cooling device 302 in FIG. 10 is connected to the radiator 13 connected between the discharge side piping of the compressor 1 and the oil separator 3, and a part of the air blown from the blower 16 to the radiator 13. And a damper 311 for blocking or passing the air flow. Note that a duct for guiding the wind from the blower 16 may be installed between the blower 16 and the radiator 13. The damper 311 has a function of changing the direction in which the wind sent from the blower 16 hits the heat radiator 13 and the direction in which the air is blocked, and its operation is controlled by the heat radiation control means 322. In addition, a cooling effect can be enlarged by attaching a fin etc. to the heat radiator 13 and enlarging a surface area.

The heat radiation control means 322 controls to open the damper 311 and send wind to the radiator 13 during the cooling operation. Then, the discharge gas is cooled in the radiator 13. On the other hand, the heat dissipation control means 322 closes the damper 311 during the heating operation and blocks the wind to the radiator 13. Then, the discharge gas cooling device 2 does not cool the discharge gas.

Even in Embodiment 4 described above, since the separation of the refrigeration oil from the refrigerant is promoted, the pressure loss from the evaporator outlet to the compressor suction is reduced during the cooling operation, and the discharge gas cooling device 302 radiates heat. By doing so, COP can be improved. On the other hand, since cooling (heat radiation) is not performed in the discharge gas cooling device 302 during heating operation, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) 6 can be prevented, and COP reduction can be prevented. Furthermore, with the configuration as shown in FIG. 10, the heat dissipation amount of the radiator 13 can be adjusted only by the outdoor unit 10.

Embodiment 5. FIG.
FIG. 11 is a schematic view showing Embodiment 5 of the air-conditioning apparatus of the present invention, and the air-conditioning apparatus 400 will be described with reference to FIG. In addition, in the air conditioning apparatus 400 of FIG. 11, the site | part which has the same structure as the air conditioning apparatus 100 of FIG. 1 attaches | subjects the same code | symbol, and abbreviate | omits the description. The air conditioning apparatus 400 in FIG. 11 is different from the air conditioning apparatus 100 in FIG. 1 in the configuration of the discharge gas cooling apparatus.

The discharge gas cooling device 402 performs heat exchange between the pump 12, the radiator 13 connected to the pump 12, and the discharge gas from the compressor 1 connected to the radiator 13 and circulating water. A second one connected to the discharge pipe of the compressor 1 and the heat exchanger 14, one of which is bypassed from the discharge pipe of the compressor 1 to the inlet of the oil separator 3. The three-way valve 418 is provided. That is, a flow path through which the discharge gas from the compressor 1 passes through the heat exchanger 14 by switching the second three-way valve, and a flow path that bypasses the heat exchanger 14 and flows to the oil separator 3. Will be switched. The operation of the second three-way valve 418 is controlled by the heat radiation control means 22.

The heat dissipation control means 422 switches the second three-way valve 418 so that the discharge gas from the compressor 1 passes through the heat exchanger 14 during the cooling operation. Then, the discharge gas is cooled in the heat exchanger 14. On the other hand, the heat release control means 422 switches the second three-way valve 418 so as to bypass the heat exchanger 14 that performs heat exchange with the discharge pipe of the compressor 1 during the heating operation. Then, the discharge gas flows into the oil separator 3 without passing through the heat exchanger 14, and the discharge gas is not cooled.

Even in the fifth embodiment described above, since the separation of the refrigerating machine oil from the refrigerant is promoted, the pressure loss of the compressor suction from the evaporator outlet is reduced during the cooling operation, and the discharge gas cooling device 402 reduces the refrigerant pressure. COP can be improved by performing heat dissipation. On the other hand, since cooling (heat radiation) is not performed in the discharge gas cooling device 402 during heating operation, reduction of the enthalpy difference in the outdoor heat exchanger (condenser) 6 can be prevented, and COP reduction can be prevented.

The embodiment of the present invention is not limited to the above embodiment. For example, the heat radiation control means 22, 222, 322, and 422 exemplify a case where control is performed so that heat is dissipated during cooling operation, and heat is not dissipated when cooling operation is not performed. You may adjust so that it may do. For example, when the cooling operation is performed as shown in FIG. 8 and is lower than the set operation frequency fref, the flow rate on the cooling flow path 14a side in the heat exchanger 14 is reduced, or the air flow to the radiator 13 in FIG. Cooling may be performed in a state where the cooling capacity is set low by controlling the damper 311 so as to reduce the amount to be reduced.

Further, the case where a hollow container is used as an example of the configuration of the oil separator 3 is illustrated. For example, a method in which the flow rate of the refrigerant gas is decreased and oil fine particles are dropped by its own weight, and a filter is provided in the oil separator. Various known techniques such as a method of collecting the fine particles can be used.

1 compressor, 2, 202, 302, 402 discharge gas cooling device, 3 oil separator, 4 four-way valve, 5 gas side extension piping, 6 indoor heat exchanger, 7 refrigerant liquid side extension piping, 8 expansion valve, 9 outdoor Heat exchanger, 10 outdoor unit, 11 indoor unit, 12 pump, 13 radiator, 14 heat exchanger, 14a cooling flow path, 16 blower, 20 outdoor unit controller, 21 operation determination means, 22, 222, 322, 422 Control means, 100, 200, 300, 400, air conditioner, 215, first three-way valve, 311 damper, 418, second three-way valve, f operating frequency, fref set operating frequency.

Claims

Compressor, discharge gas cooling device, oil separator, four-way valve, indoor heat exchanger, expansion valve, outdoor heat exchanger have a refrigerant circuit connected in an annular shape, cooling operation by switching the flow path by the four-way valve And an air conditioner capable of heating operation,
An operation determination means for determining whether the operation state is a cooling operation or a heating operation;
When the operation determination unit determines that the cooling operation is performed, the discharge gas cooling device is controlled to cool the discharge gas discharged from the compressor, and when it is determined that the heating operation is performed, the discharge An air conditioner comprising: heat radiation control means for controlling the discharge gas cooling device so as not to cool the gas.
The heat dissipation control means has a function of detecting the operation frequency of the compressor, and the operation determination means determines that the operation is in the cooling operation, and the detected operation frequency is preset. 2. The air according to claim 1, wherein the discharge gas is cooled when it is equal to or higher than the set operation frequency, and the discharge gas is not cooled when the frequency is lower than the set operation frequency. Harmony device.
The discharge gas cooling device comprises:
A pump for circulating the circulating material, a radiator for dissipating the circulating material connected to the pump, and heat for exchanging heat between the circulating material and the discharge gas connected to the radiator and the pump. With an exchange,
The heat radiation control means drives the pump during cooling operation to cool the discharge gas in the heat exchanger, and stops heating the pump during heating operation to cool the discharge gas in the heat exchanger. It controls so that it may not perform, The air conditioning apparatus of Claim 1 or 2 characterized by the above-mentioned.
The discharge gas cooling device comprises:
A heat exchanger having a refrigerant flow path through which the discharge gas from the compressor flows, and a cooling flow path connected to a suction side pipe of the compressor so that suction gas sucked into the compressor flows in; ,
A first three-way valve connected to the outflow side of the cooling flow path of the heat exchanger, one of which is connected to the suction side piping of the compressor;
The heat dissipation control means circulates the suction gas through the cooling channel of the heat exchanger during cooling operation to cool the discharge gas, and the suction into the cooling channel of the heat exchanger during heating operation. The air conditioner according to claim 1 or 2, wherein the first three-way valve is controlled so as to stop the outflow of gas and not cool the discharge gas.
The outdoor heat exchanger is provided with a blower;
The discharge gas cooling device is arranged between the discharge pipe of the compressor and the oil separator, and between the radiator and the blower. It is equipped with a damper that can be opened or closed to block or pass,
The heat dissipation control means opens the damper during cooling operation and applies the air blown from the blower to the radiator to cool the discharged gas, and closes the damper during heating operation to connect the blower to the radiator. The air conditioner according to claim 1 or 2, wherein the damper is controlled so as not to cool the discharge gas by shutting off the blowing.
The discharge gas cooling device includes a pump for circulating the circulating material, a radiator for radiating heat of the circulating material connected to the pump, the circulating material and the discharge gas connected to the radiator and the pump. A heat exchanger for exchanging heat with each other, and two are connected between a discharge side pipe of the compressor and a suction side pipe of the heat exchanger, one of which is connected to the discharge side of the heat exchanger and the A second three-way valve connected between the oil separator inlet and
The heat radiation control means cools the discharge gas by passing the discharge gas through the heat exchanger during the cooling operation, and prevents the discharge gas from being cooled without passing through the heat exchanger during the heating operation. The air conditioner according to claim 1 or 2, wherein the second three-way valve is controlled.
A compressor, a discharge gas cooling device, an oil separator, a flow path switch, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger have a refrigerant circuit connected in a ring shape, and the flow path by the flow path switch A control method of an air conditioner capable of cooling operation and heating operation by switching,
Determine whether the operating state is cooling operation or heating operation,
When it is determined that the cooling operation is performed, the discharge gas cooling device is controlled to cool the discharge gas discharged from the compressor, and when it is determined that the heating operation is performed, the discharge gas is not cooled. And controlling the discharge gas cooling device. A control method for an air conditioner.