JP2008249236A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of preventing degradation of heating capacity in a defrosting operation, in particular when a temperature of the outside air is low, and keeping a comfortable indoor environment. <P>SOLUTION: This air conditioner 100 comprises a main circuit constituted by successively connecting a compressor 11 having an injection port, a four-way valve 12, a load-side heat exchanger 51, a load-side throttling device 52, a refrigerant heat exchanger 17, a heat source-side restriction device 16, and divided heat exchangers 14a-14c constituting a heat source-side heat exchanger 14 by refrigerant pipes, an injection circuit constituted by successively connecting a restriction device 18 for bypass, the refrigerant heat exchanger 17 and an injection port of the compressor 11 by an injection pipe 4 obtained by branching the refrigerant pipe connecting the refrigerant heat exchanger 17 and the load-side restriction device 52, and a defrost circuit constituted by connecting the branching pipes 3 obtained by branching the refrigerant pipe connecting the compressor 11 and the four-way valve 12, to the divided heat exchangers 14a-14c. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air conditioner capable of performing a defrost operation of a heat source side heat exchanger, and more particularly to an air conditioner capable of suppressing a decrease in heating capacity during a defrost operation and maintaining a comfortable indoor environment. .

  When heating operation is performed in an area where the outside air temperature is minus 10 ° C. or less (hereinafter referred to as low outside air), frost is likely to adhere to the heat source side heat exchanger. For this reason, the operation | movement for removing frost, ie, a defrost operation, is requested | required of an air conditioning apparatus. In an air conditioner that performs defrosting operation, a bypass pipe is provided in the discharge side piping of the compressor, and the discharge refrigerant (hot gas) from the compressor is directly guided to the heat source side heat exchanger to adhere to the heat source side heat exchanger. It is common practice to melt frost.

  As such, "a refrigerant circuit is formed by a compressor, a four-way valve, an outdoor heat exchanger, a throttle and an indoor heat exchanger, and a cooler is configured using a circuit below the outdoor heat exchanger, In a heat pump air conditioner that forms a bypass circuit that leads a part of the discharge gas of the compressor to the suction side of the compressor through the cooler, an electromagnetic on-off valve, and a throttle, when the temperature of the compressor rises The electromagnetic on-off valve in the bypass circuit is opened, the refrigerant liquefied by the cooler is bypassed to the suction side of the compressor to cool the compressor, and the electromagnetic on-off valve in the bypass circuit is opened during defrost operation. And an operation method of a heat pump type air conditioner in which frost in the lower part of the outdoor heat exchanger is melted with discharged refrigerant gas introduced into the cooler has been proposed (for example, see Patent Document 1). ).

  In addition, “in an air conditioning apparatus in which an air conditioning refrigerant circuit includes a compressor, an air conditioning switching valve, an outdoor heat exchanger, an expansion valve, a plurality of indoor heat exchangers, and an accumulator, a pipe that connects the compressor and the air conditioning switching valve. A bypass circuit that branches from the outdoor heat exchanger and returns to the accumulator without passing through the plurality of indoor heat exchangers, and a bypass valve provided in the middle of the bypass circuit is connected to the indoor heat exchanger. An air conditioner that opens in accordance with a decrease in the number of operating units and heats the refrigerant passing through the bypass circuit by releasing heat to the outside by the outdoor heat exchanger is proposed (for example, see Patent Document 2). .

JP-A-6-341740 (2nd page, Fig. 1) Patent No. 3791019 (page 3, Fig. 1)

  The operation method of the heat pump type air conditioner described in Patent Document 1 bypasses the refrigerant liquefied by the cooler during the heating operation to the compressor, and prevents an abnormal increase in the temperature of the compressor and flows into the cooler. The frost adhering to the lower part of the outdoor heat exchanger and the drain pan is reliably melted by the refrigerant. However, in the defrost operation, the refrigerant is circulated in the reverse cycle as in the heating operation. Therefore, the load-side heat exchanger is stopped, causing not only a decrease in the room temperature, but also the condensation temperature immediately increases after the defrost operation. However, there was a problem that air blowing lower than human skin temperature was performed, and the feeling of comfort was hindered.

  In the air conditioner described in Patent Document 2, the refrigerant is caused to flow into the outdoor heat exchanger by the bypass circuit, and the heat stored in the refrigerant is released to the outside by the outdoor heat exchanger. Certainly, the heat released by the outdoor heat exchanger can be used for the defrost operation. However, due to the same problem as the technique described in Patent Document 1, there is a problem that the room temperature is lowered and the comfortable feeling is hindered. In particular, in areas where the outside air is low, the flow rate of the refrigerant sucked into the compressor decreases as the outside air decreases. Would be further increased.

  The present invention has been made to solve the above-described problems. An air conditioner that can maintain a comfortable indoor environment by suppressing a decrease in heating capacity at the time of defrost operation, particularly when the outside air is low. The purpose is to provide.

  An air conditioner according to the present invention includes a compressor having an injection port, a load-side heat exchanger, a load-side expansion device, a heat-source-side expansion device, and a heat source-side heat exchanger composed of a plurality of heat exchangers as refrigerant piping. An injection circuit in which a bypass expansion device and an injection port of the compressor are connected by an injection pipe branched from a refrigerant pipe connecting the refrigerant heat exchanger and the load side expansion device; A defrost circuit in which a branch pipe obtained by branching a refrigerant pipe connecting the load side heat exchanger and the high pressure side of the compressor is connected to a plurality of heat exchangers constituting the heat source side heat exchanger; It is provided with.

  In the air conditioner according to the present invention, the heat source side heat exchanger is composed of a plurality of heat exchangers, and the defrost operation can be executed in units of each heat exchanger, and the speed of the compressor is increased during the defrost operation, or the compressor Since the amount of injection into the air is increased, particularly when the outside air is low, it is possible to suppress a decrease in the heating capacity during the defrost operation and to keep the indoor environment comfortable.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of an air-conditioning apparatus 100 according to Embodiment 1 of the present invention. The circuit configuration of the air conditioner 100 will be described with reference to FIG. The air conditioner 100 performs a cooling operation and a heating operation using a refrigeration cycle (heat pump cycle) for circulating a refrigerant. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  The air conditioner 100 is roughly composed of a heat source side unit (outdoor unit) 10 and two load side units (indoor units) 50. In FIG. 1, a state in which the load side unit 50 a and the load side unit 50 b are connected to the heat source side unit 10 in parallel is shown as an example. The heat source side unit 10, the load side unit 50a, and the load side unit 50b are connected and connected by a liquid pipe 1 that is a refrigerant pipe and a gas pipe 2 that is a refrigerant pipe. In the following description, the load side unit 50a and the load side unit 50b may be collectively referred to as the load side unit 50.

  The heat source unit 10 includes a compressor 11, a four-way valve 12, a heat source side heat exchanger 14, a heat source side expansion device 16, a refrigerant heat exchanger 17, and a bypass expansion device 18. Moreover, in the heat source side unit 10, the discharge side piping which connects the compressor 11 and the four-way valve 12 and the heat source side heat exchanger 14 are connected by the branch piping 3 which branched the discharge side piping. . Further, in the heat source side unit 10, the injection pipe 4 that branches the liquid pipe 1 between the refrigerant heat exchanger 17 and a load side expansion device 52 described later is connected to the injection port of the compressor 11.

  The compressor 11 sucks the refrigerant and compresses the refrigerant to a high temperature / high pressure state, and is configured by a capacity controllable capable of increasing the speed according to the rated frequency. The compressor 11 is provided with an injection port, and the injection pipe 4 is connected to the injection port so that a refrigerant can be injected (injected) into the compression chamber inside the compressor 11. . The four-way valve 12 functions as a flow path switching valve, and switches the flow of refrigerant during cooling operation, heating operation, and defrost operation.

  As shown in FIG. 1, the heat source side heat exchanger 14 includes a plurality of heat exchangers including a divided heat exchanger 14a, a divided heat exchanger 14b, and a divided heat exchanger 14c. The condenser functions as an evaporator during heating operation, and performs heat exchange between the air supplied from the outdoor unit air blowing means 20 and the refrigerant, and evaporates or condenses the refrigerant. The liquid pipe 1 and the branch pipe connected to the heat source side heat exchanger 14 also branch according to the number of stages of the heat source side heat exchanger 14, and the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c. To be connected to each of the. In the following description, the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c may be collectively referred to as the heat source side heat exchanger 14.

  The heat source side expansion device 16 functions as a pressure reducing valve or an expansion valve, and expands the refrigerant by reducing the pressure. The heat source side expansion device 16 may be constituted by a device whose opening degree can be variably controlled, for example, an electronic expansion valve. The refrigerant heat exchanger 17 performs heat exchange between the refrigerants. The bypass throttling device 18 is provided in the injection circuit, functions as a pressure reducing valve and an expansion valve, and expands the refrigerant by decompressing it. The bypass expansion device 18 may be constituted by a device whose opening degree can be variably controlled, for example, an electronic expansion valve.

  The heat source side unit 10 is provided with an outdoor unit blower 20 such as a fan for blowing air to the heat source side heat exchanger 14 in the vicinity of the heat source side heat exchanger 14. Further, the refrigerant outlet of the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c (the refrigerant outlet during heating operation, that is, the gas pipe 2 between the heat source side heat exchanger 14 and the four-way valve 12). Are provided with a first on-off valve 13a, a first on-off valve 13b, and a first on-off valve 13c that are controlled to be opened and closed so as not to conduct the refrigerant. In the following description, the first on-off valve 13a, the first on-off valve 13b, and the first on-off valve 13c may be collectively referred to as the first on-off valve 13.

  The discharge side pipe connected to the compressor 11 measures the refrigerant pressure in the pipe, and the high pressure sensor 31 that measures the refrigerant pressure in the pipe measures the refrigerant pressure in the pipe for the suction side pipe connected to the compressor 11. A low pressure sensor 32 is installed. In addition, the refrigerant inlets of the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c (the refrigerant inlet 1 in the heating operation, that is, the liquid pipe 1 between the heat source side heat exchanger 14 and the heat source side expansion device 16). ) Are provided with an inlet temperature sensor 33a, an inlet temperature sensor 33b, and an inlet temperature sensor 33c for detecting the refrigerant temperature. Further, an outdoor temperature sensor 34 for detecting the ambient air temperature (outside air temperature) of the heat source unit 10 is provided in the vicinity of the outdoor unit air blowing means 20.

  Pressure information measured by the high pressure sensor 31 and the low pressure sensor 32, refrigerant temperature information detected by the inlet temperature sensor 33a, inlet temperature sensor 33b and inlet temperature sensor 33c, and temperature information detected by the outdoor temperature sensor 34 Is sent to the control means 40 to be described later. In the following description, the inlet temperature sensor 33a, the inlet temperature sensor 33b, and the inlet temperature sensor 33c may be collectively referred to as a heat source side heat exchanger inlet temperature sensor 33.

  Further, the branch pipe 3 connecting the compressor 11 and the heat source side heat exchanger 14 is provided with a second on-off valve 19a, a second on-off valve 19b, and a second on-off valve 19a that are controlled to open and close and do not conduct the refrigerant. Two on-off valves 19c are provided. That is, the second on-off valve 19a, the second on-off valve 19b, and the second on-off valve 19c are provided in each of the branch pipes 3 branched according to the number of stages of the heat source side heat exchanger 14. In the following description, the second on-off valve 19a, the second on-off valve 19b, and the second on-off valve 19c may be collectively referred to as the second on-off valve 19.

  Further, the heat source side unit 10 is equipped with a control means 40 that performs overall control of the entire air conditioner 100. This control means 40 is based on the information from each sensor mentioned above, the drive frequency of the compressor 11, the opening degree of the heat-source side expansion device 16, the bypass expansion device 18, and the load-side expansion device 52 described later, the first opening / closing. The opening and closing of the valve 13 and the second on-off valve 19 are controlled. Here, although the case where the control means 40 is provided in the heat source side unit 10 is described as an example, the present invention is not limited to this. For example, the control means 40 may be provided in the load side unit 50 or may be provided outside the heat source side unit 10 and the load side unit 50.

  A load side heat exchanger 51a and a load side expansion device 52a are connected and mounted in series on the load side unit 50a. The load unit 50a is provided with an indoor unit blowing means 53a such as a fan in the vicinity of the load side heat exchanger 51a. Further, an indoor temperature sensor 54a for detecting the temperature (indoor temperature) of the intake air of the load side unit 50a is provided in the vicinity of the indoor unit air blowing means 53a. Similarly, the load side unit 50b is also equipped with a load side heat exchanger 51b, a load side expansion device 52b, an indoor unit blower 53b, and an indoor temperature sensor 54b. In addition, the capacity | capacitance of the load side unit 50a and the load side unit 50b may differ, and may be the same.

  The load-side heat exchanger 51a and the load-side heat exchanger 51b function as an evaporator during the cooling operation and as a condenser during the heating operation, exchange heat between the refrigerant and air, and convert the refrigerant into evaporated gas or liquefaction. To do. In the following description, the load side heat exchanger 51a and the load side heat exchanger 51b may be collectively referred to as the load side heat exchanger 51. The load-side throttle device 52a and the load-side throttle device 52b function as a pressure reducing valve or an expansion valve, and decompress the refrigerant to expand it. The load-side throttle device 52a and the load-side throttle device 52b may be configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve. In the following description, the load side expansion device 52a and the load side expansion device 52b may be collectively referred to as the load side expansion device 52.

  The indoor unit air blowing means 53a and the indoor unit air blowing means 53b fulfill the function of supplying air to the load side heat exchanger 51a and the load side heat exchanger 51b. In the following description, the indoor unit blowing unit 53a and the indoor unit blowing unit 53b may be collectively referred to as the indoor unit blowing unit 53. Further, the indoor temperature sensor 54a and the indoor temperature sensor 54b may be collectively referred to as the indoor temperature sensor 54. Temperature information detected by the indoor temperature sensor 54 is also sent to the control means 40.

  The compressor 11, the four-way valve 12, the load side heat exchanger 51, the load side expansion device 52, the refrigerant heat exchanger 17, the heat source side expansion device 16, and the heat source side exchanger 14 described above are connected to the gas pipe 2 and the liquid pipe 1. The main circuit is provided with a refrigerant circuit connected in sequence. As described above, the air conditioner 100 includes the main circuit, and by circulating the refrigerant in the main circuit, the air conditioner 100 can perform the cooling operation or the heating operation based on the circulation direction of the refrigerant. It has become.

  The air conditioner 100 also includes a compressor 11, a four-way valve 12, a load side heat exchanger 51, a load side expansion device 52, a bypass expansion device 18, and a refrigerant heat exchanger 17 that are connected to the gas pipe 2, the liquid pipe 1, and the injection. A refrigerant circuit sequentially connected by the pipe 4 is provided as an injection circuit. By allowing a part of the refrigerant flowing through the main circuit to flow into the injection circuit, in the refrigerant heat exchanger 17, the refrigerant flowing through the main circuit (liquid pipe 1) and the injection circuit (injection pipe 4) flow, and the throttling device for bypass Heat can be exchanged with the refrigerant whose pressure has been reduced at 18 to a low temperature.

  Furthermore, the air conditioner 100 branches the compressor 11, the heat source side heat exchanger 14, the heat source side expansion device 16, the refrigerant heat exchanger 17, the load side expansion device 52, the load side heat exchanger 5 and the four-way valve 12 into a branch pipe. 3. A refrigerant circuit sequentially connected by a liquid pipe 1 and a gas pipe 2 is provided as a defrost circuit. By allowing the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 to flow into the heat source side heat exchanger 14 via the branch pipe 3, the defrosting operation can be performed. That is, the refrigerant discharged from the compressor 11 flows in through the branch pipes 3 connected to the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c constituting the heat source side heat exchanger 14, respectively. It can be done.

  The amount of the gas refrigerant flowing into the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c is determined by controlling the opening / closing of the second on-off valve 19a, the second on-off valve 19b, and the second on-off valve 19c. Is done. 1 shows an example in which the branch pipe 3 branches the discharge side pipe between the compressor 11 and the four-way valve 12. However, the present invention is not limited to this. For example, the four-way valve 12 The branch pipe 3 may be configured by branching the gas pipe 2 connecting the load side heat exchanger 51 and the gas pipe 2.

The refrigerant | coolant which can be used for the air conditioning apparatus 100 is demonstrated.
Examples of the refrigerant that can be used in the refrigeration cycle of the air conditioner 100 include a non-azeotropic refrigerant mixture, a pseudo-azeotropic refrigerant mixture, and a single refrigerant. Non-azeotropic refrigerant mixture includes R407C (R32 / R125 / R134a) which is an HFC (hydrofluorocarbon) refrigerant. Since this non-azeotropic refrigerant mixture is a mixture of refrigerants having different boiling points, it has a characteristic that the composition ratio of the liquid-phase refrigerant and the gas-phase refrigerant is different. The pseudo azeotropic refrigerant mixture includes R410A (R32 / R125) and R404A (R125 / R143a / R134a) which are HFC refrigerants. Since this pseudo-azeotropic refrigerant mixture is a mixture of refrigerants having a boiling point close to that of the refrigerant, it is relatively easy to handle as in the case of a single refrigerant, and about 1.1 to 1. It has the characteristic of 6 times the operating pressure.

  The single refrigerant includes R22, which is an HCFC (hydrochlorofluorocarbon) refrigerant, R134a, which is an HFC refrigerant, and the like. Since this single refrigerant is not a mixture, it has the property of being easy to handle. In addition, carbon dioxide, propane, isobutane, ammonia, etc., which are natural refrigerants, can also be used. R22 represents chlorodifluoromethane, R32 represents difluoromethane, R125 represents pentafluoroethane, R134a represents 1,1,1,2-tetrafluoroethane, and R143a represents 1,1,1-trifluoroethane. ing. Therefore, it is good to use the refrigerant | coolant according to the use and the objective of the air conditioning apparatus 100. FIG.

Here, operation | movement of the air conditioning apparatus 100 is demonstrated.
First, the heating operation in a situation where the outside air temperature is relatively high will be described. Based on FIG. 1, the heating operation of the air conditioning apparatus 100 is demonstrated with the change of a refrigerant | coolant state. When the air conditioner 100 starts the heating operation, the compressor 11 is first driven. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows out of the heat source side unit 10 via the four-way valve 12, flows through the gas pipe 2, and enters the load side heat exchanger 51 in the load side unit 50. Inflow. In the load-side heat exchanger 51, the gas refrigerant is condensed and liquefied while dissipating heat to air or water, and becomes a low-temperature / high-pressure liquid refrigerant. In other words, the heating operation is performed by giving the heat stored in the refrigerant to the air or water on the load side.

  Further, the condensed and liquefied liquid refrigerant is decompressed to an intermediate pressure by the load side expansion device 52, and becomes an intermediate pressure liquid refrigerant or a gas-liquid two-phase refrigerant. This intermediate pressure liquid refrigerant or gas-liquid two-phase refrigerant flows out of the load side unit 50, flows through the liquid pipe 1, and flows into the heat source side unit 10. Here, since the outside air temperature is relatively high, the refrigerant does not flow into the injection circuit. That is, the control means 40 controls the bypass throttling device 18 to be closed.

  In such a state, the refrigerant that has flowed into the heat source side unit 10 passes through the refrigerant heat exchanger 17 and is then decompressed by the heat source side expansion device 16 to become a low-pressure / low-temperature liquid refrigerant or a gas-liquid two-phase refrigerant. This refrigerant flows into the heat source side heat exchanger 14 and exchanges heat with air, thereby evaporating and converting to gas refrigerant. That is, the state changes to gas by absorbing heat from the air supplied to the heat source side heat exchanger 14. The gas refrigerant passes through the first on-off valve 13 and the four-way valve 12 and is then sucked into the compressor 11. In addition, since the refrigerant does not flow into the injection circuit, the refrigerant heat exchanger 17 does not perform heat exchange. Further, during the heating operation, the first on-off valve 13 is opened and the second on-off valve 19c is closed.

  Next, heating operation in a situation where the outside air temperature is relatively low, that is, the outside air temperature is minus 10 ° C. or less (low outside air) will be described. FIG. 2 is a Mollier diagram (PH diagram) showing a refrigerant state during heating operation in a situation where the outside air temperature is relatively low. Based on FIG.1 and FIG.2, the heating operation in the condition where the external temperature of the air conditioning apparatus 100 is comparatively low is demonstrated with the change of a refrigerant | coolant state. In FIG. 2, the vertical axis represents the absolute pressure (P) and the horizontal axis represents the specific enthalpy (H). In addition, the refrigerant is in a gas-liquid two-phase state at the portion surrounded by the saturated liquid line and the saturated vapor line, is liquefied on the left side of the saturated liquid line, and is gas on the right side of the saturated vapor line. It represents that it is in a state of becoming. This Mollier diagram shows the state of the R410A refrigerant.

  When the air conditioner 100 starts the heating operation, the compressor 11 is first driven. The high-temperature and high-pressure gas refrigerant (state (a)) discharged from the compressor 11 flows out of the heat source side unit 10 via the four-way valve 12, flows through the gas pipe 2, and loads in the load side unit 50. It flows into the side heat exchanger 51. In the load-side heat exchanger 51, the gas refrigerant is condensed and liquefied while dissipating heat to air or water, and becomes a low-temperature / high-pressure liquid refrigerant (state (b)). In other words, the heating operation is performed by giving the heat stored in the refrigerant to the air or water on the load side.

  Further, the condensed and liquefied liquid refrigerant is decompressed to an intermediate pressure by the load side expansion device 52, and becomes an intermediate pressure liquid refrigerant or a gas-liquid two-phase refrigerant (state (c)). This intermediate pressure liquid refrigerant or gas-liquid two-phase refrigerant flows out of the load side unit 50, flows through the liquid pipe 1, and flows into the heat source side unit 10. Here, since the outside air is low, a part of the refrigerant is allowed to flow into the injection circuit. That is, the control means 40 controls the bypass expansion device 18 to the open state, and diverts the refrigerant that has flowed into the heat source side unit 10 into the main circuit and the injection circuit.

  The refrigerant divided into the main circuit is exchanged with the low-temperature / low-pressure refrigerant (state (g)), which is diverted into the injection circuit by the refrigerant heat exchanger 17 and slightly decompressed by the bypass expansion device 18, and further cooled. Thus, a low-temperature and high-pressure liquid refrigerant is obtained (state (d)). This liquid refrigerant passes through the refrigerant heat exchanger 17 and is then depressurized by the heat source side expansion device 16 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (e)). This gas-liquid two-phase refrigerant exchanges heat with air in the heat source side heat exchanger 14, thereby evaporating gas into a gas refrigerant (state (f)). That is, the state changes to gas by absorbing heat from the air supplied to the heat source side heat exchanger 14. The gas refrigerant passes through the first on-off valve 13 and the four-way valve 12 and is then sucked into the compressor 11. During the heating operation, the first on-off valve 13 is opened and the second on-off valve 19c is closed.

  On the other hand, the refrigerant diverted to the injection circuit is decompressed by the bypass expansion device 18 and becomes a low-temperature / low-pressure gas-liquid two-phase refrigerant (state (g)). This gas-liquid two-phase refrigerant flows into the refrigerant heat exchanger 17, exchanges heat with the intermediate-pressure liquid refrigerant or gas-liquid two-phase refrigerant (state (c)) flowing through the main circuit, and is heated (state (h )). In other words, the refrigerant flowing through the injection circuit is heat-exchanged with the refrigerant flowing through the main circuit by the refrigerant heat exchanger 17 to become a slightly dry refrigerant. Then, the refrigerant flows through the injection pipe 4 and is injected into the injection port of the compressor 11.

  In the compressor 11, the refrigerant sucked through the main circuit (state (f)) is compressed and heated to an intermediate pressure (state (i)) and then injected from the injection circuit (state (h)). And join. The merged refrigerant is compressed to a high pressure (state (a)) and discharged again after the temperature is slightly lowered (state (j)). That is, in the heating operation in a situation where the outside air temperature is relatively low, the heating capacity is prevented from being lowered by using the injection circuit.

  Thus, in the heating operation in a situation where the outside air temperature is relatively low, heat exchange with the outside air must be performed, so the evaporation temperature of the refrigerant is lowered, and the evaporation pressure (low pressure) is lowered accordingly. Therefore, in an air conditioner that does not include an injection circuit, the density of the refrigerant sucked into the compressor is lowered, so that the refrigerant flow rate is reduced and the capacity of the refrigeration cycle is lowered. Become. In addition, since the compression ratio increases, the discharge temperature of the compressor may abnormally increase.

  Compared with such an air conditioner, the air conditioner 100 according to the first embodiment, which includes an injection circuit, has an intermediate pressure refrigerant (state (g)) in the compression process of the compressor 11. Can increase the refrigerant flow rate (improve the density of the refrigerant) and maintain the heating capacity even in a relatively low outside air temperature without abnormally increasing the discharge temperature from the compressor 11. It can be done. Therefore, the air conditioning apparatus 100 can keep the indoor environment comfortable even in such low outside air.

  Next, the defrost operation will be described. When the air conditioner 100 is performing the heating operation, the temperature of the heat source side heat exchanger 14 functioning as a condenser is lowered, and frost tends to adhere to the heat source side heat exchanger 14. If the state where frost is attached to the heat source side heat exchanger 14 is left unattended, the ability of the air conditioner 100 will be reduced. Therefore, the air conditioner 100 can perform defrosting operation periodically. As described above, the air conditioning apparatus 100 includes the defrost circuit for causing the refrigerant discharged from the compressor 11 to flow into the heat source side heat exchanger 14.

  The air-conditioning apparatus 100 according to Embodiment 1 sequentially performs defrosting operations of the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c. If the defrost operation of the heat source side heat exchanger is executed at a time, the heating capacity of the air conditioner will be reduced. Then, like the air conditioning apparatus 100, while utilizing an injection circuit and performing a defrost driving | operation per division | segmentation heat exchanger, it can prevent heating capacity falling. At this time, the control means 40 controls to increase the speed of the compressor 11 or increase the injection amount so as to maintain the balance between the heating operation and the defrost operation, thereby improving the efficiency of each operation.

  The control means 40 determines that frost has accumulated on the heat source side heat exchanger 14 when the temperature information detected by the heat source side heat exchanger inlet temperature sensor 33 is below a predetermined value set in advance. The defrost operation is executed step by step. The control means 40 can perform a defrost operation in steps from the divided heat exchanger 14c to the divided heat exchanger 14a. The frost accumulation of the entire heat source side heat exchanger 14 may be determined by any one of the detected temperatures of the inlet temperature sensor 33a, the inlet temperature sensor 33b, and the inlet temperature sensor 33c. The accumulation of frost in the entire heat exchanger 14 may be determined, and as described herein, the divided heat exchanger 14a and the divided heat exchanger 14b are respectively determined based on the information on the inlet temperature sensor 33a, the inlet temperature sensor 33b, and the inlet temperature sensor 33c. And the accumulation of frost in each of the divided heat exchangers 14c may be determined.

  The defrost operation will be specifically described. When the temperature information detected by the inlet temperature sensor 33c becomes equal to or less than a predetermined value set in advance, the control means 40 controls the opening of the second on-off valve 19c and controls the closing of the first on-off valve 13c. Then, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the split heat exchanger 14c via the second on-off valve 19c. This refrigerant is condensed and liquefied while melting the frost adhering to the divided heat exchanger 14c. At this time, the amount of injection to the compressor 11 is increased by increasing the speed of the compressor 11 or increasing the opening of the bypass expansion device 18. By doing so, the load-side unit 50 is reduced by reducing the heat absorption amount in the divided heat exchanger 14c and reducing the refrigerant flow rate to the load-side unit 50 by bypassing the discharge gas of the compressor 11 to the divided heat exchanger 14c. It is possible to prevent the heating capacity from being lowered.

  When the amount of frost in the divided heat exchanger 14c decreases due to the defrost operation of the divided heat exchanger 14c, the refrigerant temperature in the divided heat exchanger 14c increases. Therefore, when the temperature information of the inlet temperature sensor 33c is equal to or higher than a predetermined value set in advance, the control unit 40 determines that the defrosting of the divided heat exchanger 14c is completed, and performs the defrosting operation of the divided heat exchanger 14c. finish. That is, when it is determined that the defrosting of the divided heat exchanger 14c is completed, the control unit 40 controls the opening of the first on-off valve 13c and controls the closing of the second on-off valve 19c so that the refrigerant flows during the heating operation. To do.

  Subsequently, when the temperature information detected by the inlet temperature sensor 33b falls below a predetermined value, the control means 40 controls to open the second on-off valve 19b and control to close the first on-off valve 13b. The defrost operation of the divided heat exchanger 14b is executed. Then, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the split heat exchanger 14b via the second on-off valve 19b. This refrigerant is condensed and liquefied while melting the frost adhering to the divided heat exchanger 14b. At this time, the amount of injection to the compressor 11 is increased by increasing the speed of the compressor 11 or increasing the opening of the bypass expansion device 18. By doing so, the load-side unit 50 is reduced by reducing the heat absorption amount in the divided heat exchanger 14b and reducing the refrigerant flow rate to the load-side unit 50 by bypassing the discharge gas of the compressor 11 to the divided heat exchanger 14b. It is possible to prevent the heating capacity from being lowered.

  When the amount of frost in the divided heat exchanger 14b decreases due to the defrost operation of the divided heat exchanger 14b, the refrigerant temperature of the divided heat exchanger 14b increases. Therefore, when the temperature information of the inlet temperature sensor 33b is equal to or higher than a predetermined value, the control means 40 determines that the defrosting of the divided heat exchanger 14b is completed, and performs the defrosting operation of the divided heat exchanger 14b. finish. That is, when it is determined that the defrosting of the divided heat exchanger 14b is completed, the control unit 40 controls the opening of the first on-off valve 13b and controls the closing of the second on-off valve 19b so that the refrigerant flows during the heating operation. To do.

  Finally, when the temperature information detected by the inlet temperature sensor 33a is equal to or lower than a predetermined value, the control means 40 controls to open the second on-off valve 19a and control to close the first on-off valve 13a. Then, the defrosting operation of the divided heat exchanger 14a is executed. Then, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the split heat exchanger 14a via the second on-off valve 19a. This refrigerant condenses and liquefies while melting the frost adhering to the divided heat exchanger 14a. At this time, the amount of injection to the compressor 11 is increased by increasing the speed of the compressor 11 or increasing the opening of the bypass expansion device 18. By doing so, the load-side unit 50 is reduced by reducing the heat absorption amount in the divided heat exchanger 14a and reducing the refrigerant flow rate to the load-side unit 50 by bypassing the discharge gas of the compressor 11 to the divided heat exchanger 14a. It is possible to prevent the heating capacity from being lowered.

  When the amount of frost in the divided heat exchanger 14a decreases due to the defrost operation of the divided heat exchanger 14a, the refrigerant temperature of the divided heat exchanger 14a increases. Therefore, when the temperature information of the heat source side heat exchanger inlet temperature sensor 33a becomes equal to or higher than a predetermined value set in advance, the control means 40 determines that the defrosting of the divided heat exchanger 14a is completed, and the divided heat exchanger The defrosting operation of 14a is finished. That is, when the control means 40 determines that the defrost of the split heat exchanger 14a is completed, the control means 40 controls the opening of the first on-off valve 13a and controls the closing of the second on-off valve 19a so that the refrigerant flows during the heating operation. To do.

  As described above, in the multi-stage structure in which the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c are divided into upper and lower parts, the divided heat exchanger (here, the divided heat exchanger) The defrost operation is executed in order from the heat exchanger 14c). When the defrost operation is executed from the upper split heat exchanger, the condensed water that flows down during the defrost operation is cooled by frost adhering to the lower split heat exchanger and re-freezing. Because it will end up. Then, like this air conditioning apparatus 100, by performing a defrost operation | movement from the division | segmentation heat exchanger located in the lowest part, condensed water is cooled with the frost adhering to the division | segmentation heat exchanger located in the lower part. Can prevent re-freezing.

  On the other hand, when the control unit 40 performs the above-described defrost operation, when the information from the high pressure sensor 31, the low pressure sensor 32, and the outside air temperature sensor 34 is equal to or greater than a predetermined value set in advance. The defrosting operation is executed from the division heat exchanger located at the uppermost part instead of the defrosting operation from the divisional heat exchanger (here, the division heat exchanger 14a) located at the lowermost part. . In such a case, the control means 40 first controls to open the second on-off valve 19a and controls to close the first on-off valve 13a. That is, the refrigerant discharged from the compressor 11 does not flow into the divided heat exchanger 14c located at the lowermost part, but the refrigerant discharged from the compressor 11 flows into the divided heat exchanger 14a located at the uppermost position and is divided. First, the heat exchanger 14a is defrosted.

  When the amount of frost in the divided heat exchanger 14a decreases due to the defrost operation of the divided heat exchanger 14a, the refrigerant temperature of the divided heat exchanger 14a increases. Therefore, when the temperature information of the heat source side heat exchanger inlet temperature sensor 33a becomes equal to or higher than a predetermined value set in advance, the control means 40 determines that the defrosting of the divided heat exchanger 14a is completed, and the divided heat exchanger The defrosting operation of 14a is finished. That is, when the control means 40 determines that the defrost of the split heat exchanger 14a is completed, the control means 40 controls the opening of the first on-off valve 13a and controls the closing of the second on-off valve 19a so that the refrigerant flows during the heating operation. To do.

  Subsequently, the control means 40 controls the opening of the second on-off valve 19b, controls the closing of the first on-off valve 13b, and executes the defrost operation of the divided heat exchanger 14b. Due to the defrosting operation of the divided heat exchanger 14b, the control means 40 determines that the defrosting of the divided heat exchanger 14b is completed when the temperature information of the inlet temperature sensor 33b is equal to or higher than a predetermined value set in advance. The defrosting operation of the heat exchanger 14b is finished. That is, when it is determined that the defrosting of the divided heat exchanger 14b is completed, the control unit 40 controls the opening of the first on-off valve 13b and controls the closing of the second on-off valve 19b so that the refrigerant flows during the heating operation. To do.

  Finally, the control means 40 controls the opening of the second on-off valve 19c, controls the closing of the first on-off valve 13c, and executes the defrost operation of the divided heat exchanger 14c. Due to the defrosting operation of the divided heat exchanger 14c, the control means 40 determines that the defrosting of the divided heat exchanger 14c is completed when the temperature information of the inlet temperature sensor 33c is equal to or higher than a predetermined value set in advance. The defrosting operation of the heat exchanger 14c is finished. That is, when it is determined that the defrosting of the divided heat exchanger 14c is completed, the control unit 40 controls the opening of the first on-off valve 13c and controls the closing of the second on-off valve 19c so that the refrigerant flows during the heating operation. To do.

  As described above, the control means 40 determines the order in which the defrost operation is performed depending on whether the information from the high pressure sensor 31, the low pressure sensor 32, and the outside air temperature sensor 34 is equal to or greater than a predetermined value set in advance. It comes to decide. That is, when the high pressure sensor 31, the low pressure sensor 32, and the outside air temperature sensor 34 are equal to or higher than a predetermined value set in advance, the refrigerant pressure in the defrost can be maintained at a high level, and the temperature of the condensed water Therefore, the frost of the lower divided heat exchanger can be melted at the same time during the flow of the condensed water. Therefore, the defrost time of the divided heat exchanger 14b and the divided heat exchanger 14c can be shortened by executing the defrost operation from the divided heat exchanger located in the upper part.

  The number of divided heat exchangers that perform the defrost operation (the number of divided stages) is at least one of the heating load (the operating capacity of the load-side heat exchanger 51 of the load-side unit 50, the temperature difference between the room temperature and the set temperature, etc.). The control means 40 determines increase / decrease based on the above. For example, when the load-side unit 50 is heating only about 10% of the entire capacity, that is, when the heating load is small, the second on-off valve 19b and the second on-off valve 19c are simultaneously opened, By simultaneously closing the first on-off valve 13b and the first on-off valve 13c, the defrosting operation of the divided heat exchanger 14b and the divided heat exchanger 14c can be performed collectively. By doing so, the entire defrost time can be shortened.

  Further, for example, when the load side unit 50 is in the heating operation of about 40% of the entire capacity, the heat source side heat exchanger 14 leaves the capacity of about 40%, and the remaining 60% of the capacity is simultaneously defrosted. Can be put in. That is, it is possible to execute the defrost operation by leaving only the capacity corresponding to the operation capacity of the load side unit 50 and turning the remaining capacity to the defrost operation. As described above, since the defrost operation can be performed while leaving the divided heat exchanger having a necessary capacity, an efficient defrost operation can be realized.

  Further, when the heat source side heat exchanger 14 is divided into a plurality of parts, the number of divided heat exchangers is increased or divided by different capacities (for example, divided heat exchanger 14a: divided heat exchanger 14b: divided heat exchanger 14c). = 2: 3: 5), the type of capacity of the heat source side heat exchanger 14 to be put into the defrost operation can be increased, leaving a divided heat exchanger with a necessary capacity, Since the remaining capacity is transferred to the defrost operation and the defrost operation can be executed, a more efficient defrost operation can be realized.

  When dividing the heat source side heat exchanger 14 into different amounts, the capacity ratio of the first on-off valve 13a, the first on-off valve 13b and the first on-off valve 13c, the second on-off valve 19a, the second on-off valve 19b and the second The capacity ratio of the two on-off valves 19c may be the same as the capacity ratio of the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c. If it carries out like this, the refrigerant | coolant flow volume which flows into each division | segmentation heat exchanger can be distributed appropriately. For example, when dividing the divided heat exchanger 14a: divided heat exchanger 14b: divided heat exchanger 14c into a capacity of 2: 3: 5, Cv values (flow coefficients) of the first on-off valve 13a and the second on-off valve 19a. Is 0.1 to 0.2, the Cv value of the first on-off valve 13b and the second on-off valve 19b is 0.15-0.3, and the Cv value of the first on-off valve 13c and the second on-off valve 19c is 0.25. It is good to set it to about 0.5.

  Further, the defrost operation can be executed by reversing the refrigerant flow during the heating operation by the four-way valve 12 and allowing the refrigerant discharged from the compressor 11 to flow into the heat source side heat exchanger 14. That is, the defrosting operation can be performed by supplying the high-temperature and high-pressure refrigerant immediately after being discharged from the compressor 11 to the heat source side heat exchanger 14. The refrigerant used for this defrost operation is condensed and liquefied, and flows into the compressor 11 through the refrigerant heat exchanger 17, the load side expansion device 52, the load side heat exchanger 51, and the four-way valve 12 in this order. It has become. The two types of defrosting operations described above can be selected by the air conditioning apparatus 100 according to the usage environment and the user's wishes.

  In the first embodiment, the defrost circuit is formed by connecting the refrigerant to the branch pipe 3 that branches the discharge side pipe between the compressor 11 and the four-way valve 12. The gas pipe 2 between the valve 12 and the load side heat exchanger 51 may be branched. Further, the heat source side heat exchanger 14 may be configured by combining three separate independent heat exchangers, or the piping system of one heat source side heat exchanger 14 is internally divided into three systems. Thus, a split heat exchanger may be formed to constitute the heat source side heat exchanger 14.

Embodiment 2. FIG.
FIG. 3 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of the air-conditioning apparatus 200 according to Embodiment 2 of the present invention. The circuit configuration of the air conditioning apparatus 200 will be described based on FIG. The air conditioner 200 performs a cooling operation and a heating operation using a refrigeration cycle (heat pump cycle) for circulating a refrigerant. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  This air conditioner 200 is different from the air conditioner 100 according to Embodiment 1 in the number of outdoor unit air blowing means 20 provided in the heat source side unit 10. That is, the air conditioner 100 is configured to provide one outdoor unit air blowing means 20 with respect to the heat source side heat exchanger 14, but the air conditioner 200 is configured with respect to the heat source side heat exchanger 14. Two outdoor unit blowing means 20 (outdoor unit blowing means 20a and outdoor unit blowing means 20b) are provided. In addition, although the case where the two ventilation means are provided is shown in FIG. 2 as an example, the number of installed units is not particularly limited, and for example, three or more ventilation means may be provided.

  Thus, when providing the outdoor unit air blowing means 20a and the outdoor unit air blowing means 20b in the heat source side unit 10, stop at least one of the outdoor unit air blowing means closer to the divided heat exchanger performing the defrost operation. To control. For example, when the defrost operation of the split heat exchanger 14c is being performed, the control unit 40 continues the operation of the outdoor unit air blowing unit 20a and stops the operation of the outdoor unit air blowing unit 20b. In this way, even when the outside air temperature is low, the refrigerant temperature of the split heat exchanger (here, the split heat exchanger 14c) can be kept high, and the defrost operation is completed in a shorter time. be able to.

Embodiment 3 FIG.
FIG. 4 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of the air-conditioning apparatus 300 according to Embodiment 3 of the present invention. The circuit configuration of the air conditioner 300 will be described based on FIG. The air conditioner 300 performs a cooling operation and a heating operation using a refrigeration cycle (heat pump cycle) for circulating a refrigerant. In the third embodiment, differences from the first and second embodiments will be mainly described, and the same parts as those in the first and second embodiments will be denoted by the same reference numerals and the description will be given. Shall be omitted.

  The air conditioner 300 includes the first open / close valve 13 and the second open / close valve 19 provided in the heat source side unit 10 as a collective block, and the air conditioner 100 according to the first embodiment and This is different from the air-conditioning apparatus 200 according to Embodiment 2. In other words, the air conditioner 100 and the air conditioner 200 are configured such that each of the first on-off valves 13 is installed alone and each of the second on-off valves 19 is installed alone. The first on-off valve 13 and the second on-off valve 19 are made into a block, and the valve block 41 is formed, so that compactness is realized.

  Thus, if the 1st on-off valve 13 and the 2nd on-off valve 19 are made into a block, while being able to implement compactization of the heat source side unit 10, manufacturing processes, such as welding, can be reduced and production cost can be reduced. For example, when the split heat exchanger 14a and the split heat exchanger 14b are in the heating operation and the split heat exchanger 14c is in the defrost operation, the high-temperature and high-pressure gas that passes through the second on-off valve 19c. The heat of the refrigerant conducts heat through the valve block 41 and is transmitted to the low-temperature and low-pressure refrigerant passing through the second on-off valve 13a and the first on-off valve 13b. Therefore, heat radiation to the outside air is suppressed, and heat at the time of defrost contributes to evaporation on the non-defrost side, so that the heating capacity during defrost can be increased.

  In the first to third embodiments, the state in which two load side units 50 are connected to one heat source side unit 10 is shown as an example. However, the heat source side unit 10 and the load side unit The number of 50 connections is not particularly limited. In the first to third embodiments, the heat source side heat exchanger 14 is shown in a three-stage multistage structure as an example. However, the present invention is not limited to this. For example, the heat source side heat exchanger 14 14 may have a multistage structure with two divisions, or a multistage structure with four or more divisions.

  Further, in the first to third embodiments, the case where the heat source side heat exchanger 14 is divided into upper and lower parts, that is, the case where the divided heat exchangers are arranged up and down has been described as an example, but the present invention is not limited thereto. Absent. For example, the heat source side heat exchanger 14 may be configured by horizontally arranging a plurality of divided heat exchangers. That is, the heat source side heat exchanger 14 includes a plurality of divided heat exchangers (for example, the divided heat exchanger 14a, the divided heat exchanger 14b, and the divided heat exchanger 14c), and the branch pipe 3 is provided in each divided heat exchanger. It only has to be connected.

  The air conditioning apparatus 100 to the air conditioning apparatus 300 can be applied to a refrigeration apparatus, a room air conditioner, a packaged air conditioner, a refrigerator, a humidifier, a humidity control apparatus, a heat pump water heater, and the like. Therefore, the refrigerant to be used, the number of connected heat source units 10, and the number of connected load units 50 may be determined according to the purpose / use of the air conditioner 100 to the air conditioner 300. Moreover, the control means 40 is good to comprise with the microcomputer etc. which can control the air conditioning apparatus 100-the air conditioning apparatus 300 whole. Furthermore, a plurality of air blowing means may be installed in the heat source side unit 10 of the air-conditioning apparatus 300 according to Embodiment 3.

3 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of the air-conditioning apparatus according to Embodiment 1. FIG. It is a Mollier diagram (PH diagram) showing a refrigerant state of heating operation at the time of low outside air. 6 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of an air-conditioning apparatus according to Embodiment 2. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of an air-conditioning apparatus according to Embodiment 3. FIG.

Explanation of symbols

  1 liquid pipe, 2 gas pipe, 3 branch pipe, 4 injection pipe, 10 heat source side unit, 11 compressor, 12 four-way valve, 13 first on-off valve, 13a first on-off valve, 13b first on-off valve, 13c first On-off valve, 14 heat source side heat exchanger, 14a divided heat exchanger, 14b divided heat exchanger, 14c divided heat exchanger, 16 heat source side expansion device, 17 refrigerant heat exchanger, 18 bypass expansion device, 19 second opening / closing Valve, 19a second on-off valve, 19b second on-off valve, 19c second on-off valve, 20 air blowing means, 20a air blowing means, 20b air blowing means, 31 high pressure sensor, 32 low pressure sensor, 33 heat source side heat exchanger inlet temperature Sensor, 33a heat source side heat exchanger inlet temperature sensor, 33b heat source side heat exchanger inlet temperature sensor, 33c heat source side heat exchanger inlet temperature sensor, 40 control means, 41 valve block, 50 load side unit, 50a load side unit, 50b load side unit, 51 load side heat exchanger, 51a load side heat exchanger, 51b load side heat exchanger, 52 load side throttle device, 52a load side throttle Apparatus, 52b load side throttle device, 53 air blowing means, 53a air blowing means, 53b air blowing means, 54 indoor temperature sensor, 54a indoor temperature sensor, 54b indoor temperature sensor, 100 air conditioner, 200 air conditioner, 300 air conditioner.

Claims (14)

A main circuit in which a compressor having an injection port, a load side heat exchanger, a load side expansion device, a heat source side expansion device, and a heat source side heat exchanger composed of a plurality of heat exchangers are connected by refrigerant piping;
An injection circuit in which a bypass expansion device and an injection port of the compressor are connected by an injection pipe branched from a refrigerant pipe connecting the refrigerant heat exchanger and the load side expansion device;
A defrost circuit in which a branch pipe obtained by branching a refrigerant pipe connecting the load side heat exchanger and the high pressure side of the compressor is connected to each of the plurality of heat exchangers constituting the heat source side heat exchanger. An air conditioner characterized by comprising. A four-way valve provided in a refrigerant pipe connecting the compressor and the load-side heat exchanger;
A refrigerant heat exchanger provided in the injection circuit and performing heat exchange between the refrigerant flowing through the main circuit and the refrigerant flowing through the injection circuit;
The branch pipe of the defrost circuit is branched from a refrigerant pipe connecting the four-way valve and the compressor or a refrigerant pipe connecting the four-way valve and the load-side heat exchanger. The air conditioning apparatus according to 1. The air conditioner according to claim 1 or 2, wherein the heat source side heat exchanger has a multistage structure in which a plurality of heat exchangers constituting the heat source side heat exchanger are arranged vertically. Each branch pipe connected to each heat exchanger constituting the heat source side heat exchanger by providing a first on-off valve in the refrigerant pipe connecting the four-way valve and each heat exchanger constituting the heat source side heat exchanger The air conditioner according to any one of claims 1 to 3, wherein a second on-off valve is provided. The air conditioner according to any one of claims 1 to 4, comprising a plurality of outdoor unit air blowing means for supplying air to the heat source side heat exchanger. The air conditioner according to claim 4 or 5, wherein the first on-off valve and the second on-off valve are formed into a collective block. Control means for performing a defrost operation for switching the four-way valve to supply the refrigerant discharged from the compressor to the heat source side heat exchanger;
The control means includes
By controlling the opening and closing of the first on-off valve and the second on-off valve, the defrosting operation of the heat source side heat exchanger is executed for each heat exchanger constituting the heat source side heat exchanger. The air conditioning apparatus according to any one of claims 1 to 6. The control means includes
8. The air conditioner according to claim 7, wherein when performing the defrosting operation, the bypass throttle device is controlled to open and the compressor is controlled to increase speed. An indoor temperature sensor for detecting the indoor temperature is provided,
The control means includes
The heat source side heat exchange for performing the defrost operation based on at least one of an operating capacity of the load side heat exchanger, a temperature difference between a room temperature from the room temperature sensor and a preset temperature set in advance. The air conditioner according to claim 7 or 8, wherein the increase or decrease of the heat exchanger constituting the cooler is determined. The control means includes
When at least one outdoor unit blower is provided, at least one of the outdoor unit blowers close to the heat exchanger constituting the heat source side heat exchanger during the defrost operation is stopped. The air conditioning apparatus in any one of 7-9. A high-pressure sensor that measures the pressure of the refrigerant discharged from the compressor;
A low pressure sensor for measuring the pressure of the refrigerant sucked into the compressor;
An outside air temperature sensor for detecting the outside air temperature,
The control means includes
Whether the information from the high pressure sensor, the low pressure sensor, and the outside temperature sensor is equal to or greater than a predetermined value set in advance, the order of defrost operation of the heat exchanger constituting the heat source side heat exchanger is determined. It determines. The air conditioning apparatus in any one of Claims 7-10 characterized by the above-mentioned. The control means includes
When the information from the high pressure sensor, the low pressure sensor, and the outside temperature sensor is less than a predetermined value set in advance, the heat exchanger located at the bottom of the heat source side heat exchanger is sequentially defrosted. The air conditioner according to claim 11, wherein operation is performed. The control means includes
When the information from the high pressure sensor, the low pressure sensor, and the outside temperature sensor is equal to or greater than a predetermined value set in advance, the defrost is sequentially performed from the heat exchanger located at the top of the heat source side heat exchanger. The air conditioner according to claim 11, wherein operation is performed. A heat source side heat exchanger inlet temperature sensor for detecting the temperature of the refrigerant in the heat source side heat exchanger;
The control means includes
The air conditioning apparatus according to any one of claims 7 to 13, wherein the defrosting operation is terminated based on information from the heat source side heat exchanger inlet temperature sensor.

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