WO2015059792A1

WO2015059792A1 - Air conditioner

Info

Publication number: WO2015059792A1
Application number: PCT/JP2013/078779
Authority: WO
Inventors: 傑鳩村; 山下　浩司; 若本　慎一; 直史竹中; 渡辺　和也
Original assignee: 三菱電機株式会社
Priority date: 2013-10-24
Filing date: 2013-10-24
Publication date: 2015-04-30
Also published as: EP3062031B1; EP3062031A1; EP3062031A4; JPWO2015059792A1; JP5992112B2

Abstract

An air conditioner (100) comprises: first gas bypass piping (5) that branches from the discharge side of a compressor (10) and in which refrigerant flows to a heat source side heat exchanger (12) that is to be defrosted from among a plurality of heat source side heat exchangers (12); second gas bypass piping (7) that branches from the discharge side of the compressor (10) and in which refrigerant flows to an accumulator (13); a plurality of first opening and closing devices (30) that are provided in the first gas bypass piping (5) and that allows or blocks the passage of refrigerant flowing in the first gas bypass piping (5); and at least one second opening and closing device (35) that is provided in the second gas bypass piping (7) and that allows or blocks the passage of refrigerant flowing in the second gas bypass piping (7).

Description

Air conditioner

The present invention relates to an air conditioner.

Conventionally, in an air conditioner such as a multi air conditioning system for buildings, for example, an outdoor unit (outdoor unit) that is a heat source unit arranged outside a building is connected to an indoor unit (indoor unit) arranged inside the building by pipe connection. The refrigerant circuit is configured to circulate the refrigerant. And heating or cooling of the air-conditioning target space is performed by heating and cooling the air using the heat radiation and heat absorption of the refrigerant.

During the heating operation of such a building multi-air conditioner, the heat exchanger installed in the outdoor unit serves as an evaporator, and heat in the air is exchanged between the low-temperature refrigerant and the air, so that the moisture in the air becomes the fins of the heat exchanger. And it condenses on the heat transfer tube and forms frost on the heat exchanger. As described above, when the heat exchanger is frosted, the air path of the heat exchanger is blocked, and the heat transfer area of the heat exchanger that exchanges heat with air is reduced, which causes a problem of insufficient heating capacity.

Therefore, in general, the heating operation is stopped, the refrigerant flow is switched by the refrigerant flow switching device, and the heat exchanger installed in the outdoor unit is used as a condenser to perform the defrosting operation. . By performing such a defrosting operation, it is possible to prevent a reduction in heating capacity. However, since the indoor heating operation is also stopped while the defrosting operation is being performed, the indoor temperature is lowered and the comfort of the indoor environment is impaired.

In the conventional technology, in order to solve such problems, a plurality of heat exchangers are provided in the outdoor unit, and the discharge gas of the compressor is configured to be able to flow into each heat exchanger. Specifically, a bypass pipe is provided so that each of the plurality of heat exchangers can be bypassed via the on-off valve, and the plurality of heat exchangers are divided into an evaporator and a condenser for use in defrosting. Operation and heating operation can be performed simultaneously (see, for example, Patent Documents 1 to 3).

WO 2010/082325 (FIGS. 7, 8, etc.) US2010 / 0170270 (FIG. 2 etc.) WO2012 / 014345 (paragraph [0006], FIG. 1 etc.)

In the air conditioning apparatus described in Patent Document 1 and Patent Document 2, a plurality of outdoor heat exchangers are used, and heating operation is performed with an evaporator and defrosting operation is performed with a condenser at the same time. However, when carrying out the defrosting operation with the condenser, in order to carry out the defrosting operation by flowing only part of the gas refrigerant discharged from the compressor to the condenser and using only the sensible heat of the gas refrigerant, A sufficient enthalpy difference cannot be secured before and after the condenser. In order to obtain a sufficient defrosting capacity, it is necessary to increase the circulation amount of a part of the gas refrigerant discharged from the compressor. For this reason, the amount of refrigerant supplied to the evaporator is reduced, the indoor heating capacity is reduced, and the comfort of the indoor environment is impaired.

On the other hand, in the air conditioner described in Patent Document 3, when performing the defrosting operation with the condenser, a condensing device is provided in the flow path on the outlet side of the refrigerant of the condenser so that the opening degree can be changed. Medium pressure defrosting is enabled to store the refrigerant in the chamber. By doing this, the refrigerant pressure in the condenser is increased, and the saturation temperature of the refrigerant is set to a slightly higher temperature (about 0 ° C. to 10 ° C.) compared to 0 ° C., so that it becomes higher than the frost temperature. I have to. Therefore, the latent heat of the two-phase part of the refrigerant can be used, a sufficient enthalpy difference can be secured before and after the condenser, and a sufficient defrosting capacity can be obtained with a smaller amount of refrigerant than the above-described defrosting operation. .
Medium pressure defrost is a defrost target condenser in which the pressure of the internal refrigerant is lower than the discharge pressure of the compressor and higher than the suction pressure (pressure that is slightly higher than 0 ° C. in terms of saturation temperature). This means defrost operation that is executed in the state.

However, in order to make available the latent heat of the two-phase part of the refrigerant, it is necessary to store the refrigerant in the condenser. In other words, by storing the refrigerant in the condenser, the refrigerant amount of the entire refrigeration cycle decreases, the refrigerant amount supplied to the evaporator decreases, the indoor heating capacity decreases, and the comfort of the indoor environment is impaired. Will end up. In addition, since the latent heat of the two-phase part of the refrigerant cannot be used until the refrigerant is stored in the condenser, sufficient defrosting capacity cannot be obtained, and the defrosting time becomes longer, thereby reducing the indoor heating capacity. The comfort of the indoor environment will be impaired.

The present invention has been made against the background of the above problems. When performing a defrosting operation simultaneously with a condenser while performing a heating operation indoors, the indoor heating capacity is reduced and the defrosting capacity is reduced. An object of the present invention is to provide an air-conditioning apparatus that can suppress a decrease in the temperature.

The air conditioner according to the present invention is an air conditioner (100, 200) capable of simultaneously performing a heating operation and a defrosting operation, and includes a compressor (10), a load side heat exchanger (21), and a load side throttle. A main circuit that forms at least a heating circuit by connecting a device (22), a plurality of heat source side heat exchangers (12) connected in parallel to each other, and an accumulator (13) by refrigerant piping; and the compressor ( 10), a first gas bypass pipe (5) branched from the discharge side of the plurality of heat source side heat exchangers (12) and allowing the refrigerant to flow into the heat source side heat exchanger (12) to be defrosted, Branched from the discharge side of the compressor (10) and provided in a second gas bypass pipe (7) for allowing the refrigerant to flow into the accumulator (13) and the first gas bypass pipe (5), the first gas Flow through bypass pipe (5) A plurality of first opening / closing devices (30) for passing or blocking the refrigerant, and at least for passing or blocking the refrigerant flowing in the second gas bypass pipe (7) provided in the second gas bypass pipe (7) And a second opening / closing device (35).

The air conditioner according to the present invention operates the load-side heat exchanger as a condenser and operates a part of the heat-source-side heat exchanger as an evaporator to perform a heating operation, while the rest of the heat-source-side heat exchanger is operated. When the defrosting operation is performed by operating a part of the condenser as a condenser, the refrigerant remaining in the accumulator can be supplied to the evaporator and the condenser. Therefore, according to the air conditioning apparatus which concerns on this invention, the fall of the refrigerant | coolant amount of the whole refrigerating cycle can be suppressed, and the fall of heating capability and a defrosting capability can be suppressed. Therefore, according to the air conditioner according to the present invention, the defrosting time is shortened, the decrease in heating capacity is suppressed, and the comfort of the indoor environment is ensured.

It is a schematic circuit block diagram which shows an example of the circuit structure of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows an example of a structure of the heat source side heat exchanger of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the cooling only operation mode of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the heating only operation mode of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of implementing the defrost of the heat source side heat exchanger at the time of the defrost operation mode of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the enthalpy difference change which can be used for the defrost by the saturation temperature change in the heat source side heat exchanger which is a defrost object heat exchanger of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the heating capability ratio at the time of defrost with respect to the saturation temperature in the heat source side heat exchanger which is a defrost object heat exchanger of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control action at the time of operating the 2nd opening / closing apparatus at the time of the defrost operation mode of the air conditioning apparatus which concerns on Embodiment 1 of this invention. Saturation temperature change in which the pressure in the load-side heat exchanger is converted when the flow rate of the high-temperature and high-pressure gas refrigerant flowing into the accumulator during the defrost mode of the air-conditioning apparatus according to Embodiment 1 of the present invention is changed. FIG. It is a schematic circuit block diagram which shows another example of the circuit structure of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a schematic circuit block diagram which shows an example of the circuit structure of the air conditioning apparatus which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, in the following drawings including FIG. 1, the same reference numerals denote the same or equivalent parts, and this is common throughout the entire specification. Furthermore, the forms of the constituent elements shown in the entire specification are merely examples, and are not limited to these descriptions.

Embodiment 1 FIG.
FIG. 1 is a schematic circuit configuration diagram showing an example of a circuit configuration of an air-conditioning apparatus 100 according to Embodiment 1 of the present invention.
Based on FIG. 1, the detailed structure of the air conditioning apparatus 100 is demonstrated.
The air conditioner 100 circulates refrigerant and performs air conditioning using a refrigeration cycle. The air-conditioning apparatus 100 has a cooling only operation mode in which all the indoor units 2 to be operated are cooled, a heating only operation mode in which all the indoor units 2 to be heated are heated, or the indoor unit 2 is continuing the heating operation. A defrosting operation mode for defrosting the heat exchanger (heat source side heat exchanger 12a, heat source side heat exchanger 12b) in the outdoor unit 1 can be selected.

As shown in FIG. 1, the air conditioning apparatus 100 includes an outdoor unit 1 and an indoor unit 2, and is configured by connecting the outdoor unit 1 and the indoor unit 2 with a refrigerant main pipe 4. In the following description, the heat source side heat exchanger 12a and the heat source side heat exchanger 12b may be collectively referred to as the heat source side heat exchanger 12.

[Outdoor unit 1]
The outdoor unit 1 includes a compressor 10, a refrigerant flow switching device 11, such as a four-way valve, a heat source side heat exchanger 12a, a heat source side heat exchanger 12b, an accumulator 13, a first opening / closing device 30a, a first opening / closing device 30b, A second opening / closing device 35, a third opening / closing device 31a, a third opening / closing device 31b, a flow rate adjusting device 32a, and a flow rate adjusting device 32b are mounted. In the outdoor unit 1, these element devices are connected by a refrigerant pipe 3, a first gas bypass pipe 5, and a second gas bypass pipe 7.

The refrigerant pipe 3 connects the compressor 10, the refrigerant flow switching device 11, the heat source side heat exchanger 12a, the heat source side heat exchanger 12b, the flow rate adjusting device 32a, the flow rate adjusting device 32b, and the accumulator 13. The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are connected to each other in parallel by the refrigerant pipe 3.

One end of the first gas bypass pipe 5 is connected to the refrigerant pipe 3 between the discharge part of the compressor 10 and the refrigerant flow switching device 11. The first gas bypass pipe 5 is branched into two branches, one end of which is connected to the refrigerant pipe 3 between the heat source side heat exchanger 12a and the third switchgear 31a, and the other end is connected to the heat source side. It connects to the refrigerant | coolant piping 3 between the heat exchanger 12b and the 3rd switchgear 31b.
A first opening / closing device 30a is provided in the first gas bypass pipe 5 connected to the heat source side heat exchanger 12a.
A first opening / closing device 30b is provided in the first gas bypass pipe 5 connected to the heat source side heat exchanger 12b.

One end of the second gas bypass pipe 7 is connected to the refrigerant pipe 3 between the discharge part of the compressor 10 and the refrigerant flow switching device 11. The other end of the second gas bypass pipe 7 is connected to the refrigerant pipe 3 between the refrigerant flow switching device 11 and the accumulator 13.
A second opening / closing device 35 is provided in the second gas bypass pipe 7.

The third opening / closing device 31 a that blocks the refrigerant flowing into the heat source side heat exchanger 12 a is installed in the refrigerant pipe 3 between the heat source side heat exchanger 12 a and the refrigerant flow switching device 11.
The third opening / closing device 31b for blocking the refrigerant flowing into the heat source side heat exchanger 12b is installed in the refrigerant pipe 3 between the heat source side heat exchanger 12b and the refrigerant flow switching device 11.

The heat source side heat exchanger 12a and the heat source side heat exchanger 12b include a plurality of plate-like fins (fins 51 shown in FIG. 2) and heat transfer tubes (see FIG. 2) inserted so as to be orthogonal to the fins. And a fin tube type heat exchanger having a heat pipe 52). An example of the configuration of the heat source side heat exchanger 12 will be described based on FIG. FIG. 2 is a schematic diagram illustrating an example of the configuration of the heat source side heat exchanger 12 of the air conditioner 100.

As shown in FIG. 2, the heat source side heat exchanger 12 is divided into a plurality of heat exchangers. Here, the case where the heat source side heat exchanger 12 is divided into two heat source side heat exchangers 12a and heat source side heat exchangers 12b will be described as an example. The heat source side heat exchanger 12a and the heat source side heat exchanger 12b have two rows of fins 51 that are adjacent to each other in the row direction (the left-right direction in which each fin faces the same direction). The heat source side heat exchanger 12a and the heat source side heat exchanger 12b are each configured in two stages in the step direction of the heat transfer tubes 52 (up and down directions in which the fins face the same direction).

That is, the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are configured by dividing the heat source side heat exchanger 12 in the casing of the outdoor unit 1, so that the fins 51 face the same direction. Are arranged vertically. For example, as shown in FIG. 2, the heat source side heat exchanger 12a is disposed on the upper side, the heat source side heat exchanger 12b is disposed on the lower side, and the fins 51 in the respective step directions are integrally formed (shared). Yes.

As shown in FIG. 2, the refrigerant flow path of the heat source side heat exchanger 12a may be branched by a distributor 12a-1 and a header 12a-2. Similarly, as shown in FIG. 2, the refrigerant flow path of the heat source side heat exchanger 12b may be branched by a distributor 12b-1 and a header 12b-2.

In the configuration shown in FIG. 2, two rows of fins adjacent to each other in the row direction (left and right directions in which the respective fins face the same direction) have been described. A configuration may be used, and the path pattern may be different from that shown in FIG. Further, as the heat source side heat exchanger 12, a plurality of units such as three or more in the step direction (vertical direction in which each fin faces the same direction) is located, and the fins in each step direction are integrally formed (shared). The number of stages is not limited to the number of stages shown in FIG. 2, and a larger number or a smaller number may be provided.

A plurality of the heat transfer tubes 52 are provided in the step direction perpendicular to the air passage direction and the row direction that is the air passage direction.
The fins 51 are arranged at intervals so that air passes in the air passage direction.

The heat source side heat exchanger 12 may be divided into left and right parts. However, when the heat source side heat exchanger 12 is divided into left and right parts, the refrigerant inlets to the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are respectively connected to the outdoor unit 1. Because it becomes the left and right ends of the pipe, the pipe connection becomes complicated. For this reason, it is desirable to divide up and down as shown in FIG.

In the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the fins 51 may not be divided as shown in FIG. 2, or may be divided. Moreover, the division | segmentation of the heat source side heat exchanger 12 is not restricted to two, It can be made into arbitrary numbers.
The outdoor air is conveyed to the heat source side heat exchanger 12a and the heat source side heat exchanger 12b by a blower (not shown) such as a fan, for example.
The blower may be installed in each of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, but may share one unit.

Further, the flow rate adjusting device 32a can change the opening degree, and is provided in the refrigerant pipe 3 on the load side expansion device 22 side of the heat source side heat exchanger 12a.
The flow rate adjusting device 32b can change the opening degree, and is provided in the refrigerant pipe 3 on the load side expansion device 22 side of the heat source side heat exchanger 12b.

The compressor 10 sucks the refrigerant and compresses the refrigerant to a high temperature / high pressure state. The compressor 10 is configured by, for example, an inverter compressor capable of capacity control.
The refrigerant flow switching device 11 switches the refrigerant flow in the heating only operation mode and the refrigerant flow in the cooling only operation mode.

Both the heat source side heat exchanger 12a and the heat source side heat exchanger 12b function as an evaporator during the heating only operation mode and function as a condenser during the cooling only operation mode. Further, during the defrosting operation, one of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b functions as an evaporator and the other functions as a condenser.

The accumulator 13 is provided on the suction side of the compressor 10 and stores excess refrigerant due to a difference in operation state between the heating only operation mode and the cooling only operation mode, and excess refrigerant with respect to a transient change in operation. .

When the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode, the first switchgear 30a causes a high-temperature refrigerant to flow from the first gas bypass pipe 5 into the heat source side heat exchanger 12a. It is.
When the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode, the first opening / closing device 30b allows a high-temperature refrigerant to flow into the heat source side heat exchanger 12b from the first gas bypass pipe 5. It is.

The first opening / closing device 30a and the first opening / closing device 30b may be configured to be capable of opening and closing the refrigerant flow path, such as a two-way valve, an electromagnetic valve, and an electronic expansion valve.
In the following description, the first opening / closing device 30a and the first opening / closing device 30b may be collectively referred to as the first opening / closing device 30.

When the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode, the third opening / closing device 31a is a low-temperature two-phase flow that flows into the outdoor unit 1 from the indoor unit 2 through the refrigerant main pipe 4. The flow path of the refrigerant is blocked so that the refrigerant does not flow into the heat source side heat exchanger 12a.
When the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode, the third opening / closing device 31b is a low-temperature two-phase flow that flows into the outdoor unit 1 from the indoor unit 2 through the refrigerant main pipe 4. The refrigerant flow path is blocked so that the refrigerant does not flow into the heat source side heat exchanger 12b.

The third opening / closing device 31a and the third opening / closing device 31b may be configured to be capable of opening and closing the refrigerant flow path, such as a two-way valve, an electromagnetic valve, and an electronic expansion valve.
In the following description, the third opening / closing device 31a and the third opening / closing device 31b may be collectively referred to as the third opening / closing device 31.

The flow rate adjusting device 32a and the flow rate adjusting device 32b are throttle devices that can change the opening degree (opening area) in order to adjust the pressure in the heat source side heat exchanger 12 serving as a condenser.
The flow rate adjusting device 32a and the flow rate adjusting device 32b may be configured by, for example, an electronic expansion valve that is driven by a stepping motor, or a device that can change the opening area by arranging a plurality of small electromagnetic valves in parallel.
In the following description, the flow rate adjusting device 32a and the flow rate adjusting device 32b may be collectively referred to as the flow rate adjusting device 32.

The second opening / closing device 35 allows a part of the high-temperature / high-pressure gas refrigerant discharged from the compressor 10 to flow into the accumulator 13 during the defrosting operation mode.
The second opening / closing device 35 may be constituted by a device capable of opening and closing the refrigerant flow path, such as a two-way valve, a solenoid valve, or an electronic expansion valve.

The outdoor unit 1 is provided with a first pressure sensor 41 and a second pressure sensor 42 as pressure detection means.
The first pressure sensor 41 is provided in the refrigerant pipe 3 between the compressor 10 and the refrigerant flow switching device 11. The first pressure sensor 41 detects the pressure of the high-temperature and high-pressure refrigerant discharged from the compressor 10.
The second pressure sensor 42 is provided in the refrigerant pipe 3 between the refrigerant flow switching device 11 and the accumulator 13. The second pressure sensor 42 detects the pressure of the low-pressure refrigerant sucked into the compressor 10.

The outdoor unit 1 is provided with a first temperature sensor 43, a second temperature sensor 45, a third temperature sensor 48a, and a third temperature sensor 48b as temperature detection means. The first temperature sensor 43, the second temperature sensor 45, the third temperature sensor 48a, and the third temperature sensor 48b may be configured by a thermistor, for example.

The first temperature sensor 43 is provided in the refrigerant pipe 3 between the compressor 10 and the refrigerant flow switching device 11. The first temperature sensor 43 measures the temperature of the refrigerant discharged from the compressor 10.
The 2nd temperature sensor 45 is provided in the air suction part of either the heat source side heat exchanger 12a or the heat source side heat exchanger 12b. The second temperature sensor 45 measures the air temperature around the outdoor unit 1.

The third temperature sensor 48 a is provided in the refrigerant pipe 3 between the heat source side heat exchanger 12 a and the refrigerant flow switching device 11. The third temperature sensor 48a measures the temperature of the refrigerant flowing into the heat source side heat exchanger 12a operating as an evaporator or the refrigerant flowing out of the heat source side heat exchanger 12a operating as a condenser.
The third temperature sensor 48 b is provided in the refrigerant pipe 3 between the heat source side heat exchanger 12 b and the refrigerant flow switching device 11. The third temperature sensor 48b measures the temperature of the refrigerant flowing into the heat source side heat exchanger 12b operating as an evaporator or the refrigerant flowing out of the heat source side heat exchanger 12b operating as a condenser.

In addition, a control device 50 is installed in the outdoor unit 1. The pressure information detected by the first pressure sensor 41 and the second pressure sensor 42 and the temperature information detected by the first temperature sensor 43, the second temperature sensor 45, the third temperature sensor 48a, and the third temperature sensor 48b are: Is input to the control device 50.

[Indoor unit 2]
In the indoor unit 2, a load-side heat exchanger 21 and a load-side expansion device 22 are mounted connected in series.

The load-side heat exchanger 21 is connected to the outdoor unit 1 through the refrigerant main pipe 4, and the refrigerant flows in or out. The load-side heat exchanger 21 performs heat exchange between air and a refrigerant supplied from a blower (not shown) such as a fan, for example. The load-side heat exchanger 21 generates heating air or cooling air to be supplied to the indoor space. The heat exchange medium that exchanges heat with the refrigerant in the load-side heat exchanger 21 is not limited to air, and water, brine, or the like may be used as the heat exchange medium.

The load-side throttle device 22 has a function as a pressure reducing valve and an expansion valve, and decompresses and expands the refrigerant. The load side expansion device 22 is provided on the upstream side of the load side heat exchanger 21 in the refrigerant flow during the cooling only operation mode. The load-side throttle device 22 is configured with an opening degree that can be variably controlled. The load-side throttle device 22 may be configured with, for example, an electronic expansion valve.

The indoor unit 2 is provided with a fourth temperature sensor 46, a fifth temperature sensor 47, and a sixth temperature sensor 44 as temperature detection means. The 4th temperature sensor 46, the 5th temperature sensor 47, and the 6th temperature sensor 44 are good to comprise a thermistor etc., for example.

The fourth temperature sensor 46 is provided in the refrigerant pipe 3 between the load side expansion device 22 and the load side heat exchanger 21. The fourth temperature sensor 46 detects the temperature of the refrigerant flowing into the load side heat exchanger 21 or the refrigerant flowing out of the load side heat exchanger 21.
The fifth temperature sensor 47 is provided in the refrigerant pipe 3 between the load side heat exchanger 21 and the refrigerant flow switching device 11 of the outdoor unit 1. The fifth temperature sensor 47 detects the temperature of the refrigerant flowing into the load side heat exchanger 21 or the refrigerant flowing out of the load side heat exchanger 21.
The sixth temperature sensor 44 is provided in the air suction portion of the load side heat exchanger 21. The sixth temperature sensor 44 detects the ambient air temperature in the room.

Temperature information detected by the fourth temperature sensor 46, the fifth temperature sensor 47, and the sixth temperature sensor 44 is input to the control device 50 installed in the outdoor unit 1.

With the above configuration, the air conditioner 100 includes the compressor 10, the refrigerant flow switching device 11, the load side heat exchanger 21, the load side expansion device 22, and the heat source side heat exchanger 12a connected in parallel to each other. The heat source side heat exchanger 12b is sequentially connected by piping to form a main circuit in which the refrigerant circulates. Also, a bypass circuit that branches a part of the refrigerant discharged from the compressor 10 and flows into one of the heat source side heat exchangers 12 to be defrosted among the heat source side heat exchanger 12a and the heat source side heat exchanger 12b. Form.

In the configuration example of the first embodiment, as shown in FIG. 1, a case where one indoor unit 2 is connected to one outdoor unit 1 through the refrigerant main pipe 4 is shown as an example. However, the present invention is not limited to this configuration. A plurality of indoor units 2 may be provided, and the plurality of indoor units 2 may be connected to one outdoor unit 1 in parallel. Two or more outdoor units may be connected in parallel. Furthermore, by connecting three extension pipes in parallel or by providing a switching valve on the indoor unit side, a refrigerant circuit configuration that enables each indoor unit to perform cooling and heating simultaneous selection of cooling and heating is possible. It may be adopted.

The air conditioner 100 has a control device 50 composed of a microcomputer. The control device 50 switches the driving frequency of the compressor 10, the rotational speed of the blower (including ON / OFF), the switching of the refrigerant flow switching device 11, based on detection information from various detection means and instructions from the remote controller, Controlling the opening / closing of the opening / closing device 30a, the first opening / closing device 30b, the opening / closing of the third opening / closing device 31, the opening of the load-side throttle device 22, and the like, execute each operation mode to be described later.

In addition, in FIG. 1, although the state which the control apparatus 50 is installed in the outdoor unit 1 is shown as an example, it is not limited to this. For example, the control device 50 may be provided for each unit or may be provided in the indoor unit 2. When the control device 50 is provided for each unit, the control devices 50 may be connected to each other by a wired or wireless connection so that information can be exchanged.

Next, each operation mode executed by the air conditioner 100 will be described.
Below, each operation mode is demonstrated with the flow of a refrigerant | coolant.

[Cooling operation mode]
FIG. 3 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 is in the cooling only operation mode. Based on FIG. 3, the cooling only operation mode which the air conditioning apparatus 100 performs is demonstrated. In FIG. 3, the cooling only operation mode will be described by taking as an example a case where a cooling load is generated in the load-side heat exchanger 21. In FIG. 3, the flow direction of the refrigerant is indicated by solid arrows.

In the cooling only operation mode, the refrigerant flow switching device 11 is switched to the state shown by the solid line in FIG. The first opening / closing device 30a, the first opening / closing device 30b, and the second opening / closing device 35 are each switched to a closed state and block the refrigerant. The third opening / closing device 31a, the third opening / closing device 31b, the flow rate adjusting device 32a, and the flow rate adjusting device 32b are each switched to the open state and allow the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b via the refrigerant flow switching device 11. The high-temperature and high-pressure gas refrigerant that has flowed into the heat-source-side heat exchanger 12a and the heat-source-side heat exchanger 12b is radiated to the outdoor air in each of the heat-source-side heat exchanger 12a and the heat-source-side heat exchanger 12b, and is a high-pressure liquid refrigerant. It becomes. The high-pressure liquid refrigerant that has flowed out of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b merges through the flow rate adjustment device 32a and the flow rate adjustment device 32b, respectively, and flows out of the outdoor unit 1.

The high-pressure liquid refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4 and is expanded by the load-side expansion device 22 to become a low-temperature / low-pressure two-phase refrigerant. The two-phase refrigerant flows into the load-side heat exchanger 21 that operates as an evaporator and absorbs heat from the room air, thereby cooling the room air and becoming a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the load-side heat exchanger 21 flows into the outdoor unit 1 again through the refrigerant main pipe 4. The refrigerant flowing into the outdoor unit 1 passes through the refrigerant flow switching device 11 and the accumulator 13 and is sucked into the compressor 10 again.

The control device 50 loads the throttle device on the load side so that the superheat (superheat degree) obtained as the difference between the temperature detected by the fourth temperature sensor 46 and the temperature detected by the fifth temperature sensor 47 is constant. 22 is controlled.

[Heating operation mode]
FIG. 4 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 is in the heating only operation mode. Based on FIG. 4, the heating only operation mode which the air conditioning apparatus 100 performs is demonstrated. In FIG. 4, the heating only operation mode will be described by taking as an example a case where a thermal load is generated in the load-side heat exchanger 21. In FIG. 4, the flow direction of the refrigerant is indicated by solid line arrows.

In the heating only operation mode, the refrigerant flow switching device 11 is switched to the state shown by the solid line in FIG. The first opening / closing device 30a, the first opening / closing device 30b, and the second opening / closing device 35 are each switched to a closed state and block the refrigerant. The third opening / closing device 31a, the third opening / closing device 31b, the flow rate adjusting device 32a, and the flow rate adjusting device 32b are each switched to the open state and allow the refrigerant to pass therethrough.

When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the refrigerant flow switching device 11.

The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant. The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant flowing into the outdoor unit 1 flows into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b via the flow rate adjustment device 32a and the flow rate adjustment device 32b, respectively. The refrigerant that has flowed into the heat source side heat exchanger 12a and the heat source side heat exchanger 12b absorbs heat from the outdoor air and becomes a low-temperature / low-pressure gas refrigerant, and the compressor 10 passes through the refrigerant flow switching device 11 and the accumulator 13. Inhaled again.

The control device 50 has a constant subcool (degree of subcooling) obtained as a difference between a value obtained by converting the pressure detected by the first pressure sensor 41 into a saturation temperature and a temperature detected by the fourth temperature sensor 46. Thus, the opening degree of the load side expansion device 22 is controlled.

[Defrost operation mode]
In the defrosting operation mode, the detection results of the third temperature sensor 48a and the third temperature sensor 48b provided on the respective outlet sides of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are equal to or less than a predetermined value. Sometimes implemented. That is, the control device 50 performs the heating only operation mode, and when the detection results of the third temperature sensor 48a and the third temperature sensor 48b are below a predetermined value (for example, about −10 ° C. or less), the heat source side heat exchanger 12a, it is determined that a predetermined amount of frost has been generated on the fins of the heat source side heat exchanger 12b, and the defrosting operation mode is performed.

In addition, as frost formation determination, for example, when the saturation temperature converted from the suction pressure of the compressor 10 is significantly lower than the preset outside air temperature, or the temperature difference between the outside air temperature and the evaporation temperature is It may be carried out by a method such as when a predetermined time has passed after a predetermined value or more.

In the defrosting operation mode of the air conditioner 100, the heat source side heat exchanger 12b located on the lower side is defrosted, and then the heat source side heat exchanger 12a located on the upper side is defrosted. Of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b, the heat source side heat exchanger 12 that is not to be defrosted is operated as an evaporator, and the load side heat exchanger 21 of the indoor unit 2 is operated as a condenser. Let the heating operation continue.

(Defrosting of heat source side heat exchanger 12b)
FIG. 5 is a refrigerant circuit diagram illustrating the flow of the refrigerant when the defrosting of the heat source side heat exchanger 12b is performed in the defrosting operation mode of the air-conditioning apparatus 100. In FIG. 4, the flow direction of the refrigerant is indicated by solid line arrows.

In the defrosting operation mode, the refrigerant flow switching device 11 is maintained in the state shown by the solid line in FIG.
In the defrosting operation mode, the states of the first opening / closing device 30, the second opening / closing device 35, the third opening / closing device 31, and the flow rate adjusting device 32 when the heat source side heat exchanger 12b is to be defrosted are as follows. Street.
Both are controlled by the control device 50.

The first opening / closing device 30b is switched to the open state and allows the refrigerant to pass therethrough.
The third opening / closing device 31b is switched to the closed state and blocks the refrigerant.
The first opening / closing device 30a is maintained in a closed state and blocks the refrigerant.
The third opening / closing device 31a is maintained in the open state and allows the refrigerant to pass therethrough.
The flow rate adjusting device 32a is set to a fully open state and allows the refrigerant to pass therethrough.
The flow rate adjusting device 32b has a preset pressure at which the saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b is greater than 0 ° C. in terms of saturation temperature (for example, about 0.8 MPa for R410A refrigerant). The opening is controlled so that is constant.

When the outdoor air temperature detected by the second temperature sensor 45 is equal to or lower than a second predetermined value (for example, 0 ° C. or lower), the second opening / closing device 35 or the compressor 10 detected by the second pressure sensor 42 is used. When the pressure of the suction part is less than a first predetermined value (for example, about 0.3 MPa or less with R410A refrigerant), when one or both of them are satisfied, the open state is maintained and the refrigerant passes. Let
The second temperature sensor 45 and the second pressure sensor 42 correspond to the “defrosting refrigerant amount decrease detecting means” of the present invention.

If one of the determinations of the second temperature sensor 45 and the second pressure sensor 42 is satisfied during the defrosting operation mode, the amount of refrigerant circulating in the main circuit may be regarded as insufficient. By determining both, even when one of the sensors fails, the function as the “defrosting refrigerant amount decrease detecting means” can be more reliably performed.

FIG. 6 is a diagram showing a change in enthalpy difference that can be used for defrosting due to a saturation temperature change in the heat source side heat exchanger 12 that is a defrost target heat exchanger of the air conditioner 100. In FIG. 6, the horizontal axis indicates the saturation temperature in the heat source side heat exchanger 12 that is the defrost target heat exchanger, and the left side of the vertical axis indicates the average refrigerant density (kg / kg) in the heat source side heat exchanger 12 that is the defrost target heat exchanger. m ³ ), and the right side of the vertical axis represents the enthalpy difference (kJ / kg) at the entrance and exit of the heat source side heat exchanger 12 which is the defrost target heat exchanger. Moreover, the continuous line of FIG. 6 has shown the required average refrigerant | coolant density with respect to the saturation temperature in the heat source side heat exchanger 12 which is a defrost object heat exchanger, and the broken line of FIG. 6 shows the heat source side heat exchange which is a defrost object heat exchanger. The enthalpy difference which can be used for the defrosting by the saturation temperature change in the vessel 12 is shown.

From the broken line in FIG. 6, the enthalpy difference that can be used for defrosting increases in the vicinity of about 1 ° C. where the saturation temperature in the heat source side heat exchanger 12 that is the defrost target heat exchanger is greater than 0 ° C. It becomes clear that the latent heat of the part can be used more effectively, and the required average refrigerant density in the heat source side heat exchanger 12 at that time is about 600 (kg / m ³ ) or more. That is, when carrying out the defrosting operation that effectively uses the latent heat of the two-phase part of the refrigerant, it is necessary to store a refrigerant having an average refrigerant density of about 600 (kg / m ³ ) or more in the heat source side heat exchanger 12. There is.

During the defrosting operation mode, when supplying a refrigerant having an average refrigerant density of about 600 (kg / m ³ ) or more into the heat source side heat exchanger 12, the load side heat used as a condenser for heating operation The refrigerant in the exchanger 21 moves into the heat source side heat exchanger 12. Therefore, the amount of refrigerant in the load-side heat exchanger 21 decreases, so that the pressure (high pressure) in the load-side heat exchanger 21 decreases, and the low pressure also decreases due to the decrease in the amount of gas refrigerant in the entire cycle. When the load-side heat exchanger 21 is used as a condenser, it is necessary to supply indoor air at a temperature that does not give the user unpleasant feeling due to cold air.

Therefore, a predetermined temperature difference (for example, 10 ° C. or more) is required between the room temperature and the saturation temperature at the pressure in the load-side heat exchanger 21. For example, according to Japanese Industrial Standard JIS-B8616, which is a standard for performance tests of packaged air conditioners, when the set temperature of the indoor environment during heating operation is 20 ° C., the pressure in the load-side heat exchanger 21 The saturation temperature is required to be 30 ° C. or higher. Therefore, in the defrosting operation mode, the pressure on the low-pressure side in the situation where the saturation temperature in the pressure in the load-side heat exchanger 21 can be secured at 30 ° C. or more is about the first predetermined value of about 0.3 MPa. It becomes.

In the defrosting operation mode in which the outdoor air temperature is about 0 ° C. or less, which is the second predetermined value, the low pressure side pressure is in an operating state below about 0.3 MPa. Therefore, in order to store the refrigerant in the heat source side heat exchanger 12 while suppressing a decrease in the pressure on the low pressure side, it is necessary to supply a refrigerant that is not used in the heating operation and the defrosting operation.

The refrigerant flow during the defrosting operation mode will be described in detail.
When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant.
A part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows through the first gas bypass pipe 5 and is depressurized by the first switchgear 30b so as to become higher than 0 ° C. in terms of saturation temperature, and the medium pressure -It becomes a high-temperature gas refrigerant and flows into the heat source side heat exchanger 12b. The medium-pressure / high-temperature gas refrigerant flowing into the heat source side heat exchanger 12b is a two-phase refrigerant having a low intermediate pressure while melting frost adhering to the heat source side heat exchanger 12b, or an intermediate pressure liquid refrigerant. And passes through the flow rate adjusting device 32b. The refrigerant that has passed through the flow rate adjusting device 32b joins the two-phase refrigerant or liquid refrigerant having a low intermediate pressure and low temperature that has flowed into the outdoor unit 1 from the indoor unit 2 and upstream of the flow rate adjusting device 32a.

The other part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the refrigerant flow switching device 11. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant. The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant that has flowed into the outdoor unit 1 merges with the refrigerant from the flow rate adjusting device 32b upstream of the flow rate adjusting device 32a, and flows into the heat source side heat exchanger 12a. The refrigerant flowing into the heat source side heat exchanger 12a absorbs heat from the outdoor air and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the heat source side heat exchanger 12a is again sucked into the compressor 10 via the refrigerant flow switching device 11 and the accumulator 13.

The control device 50 has a preset pressure at which the saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b is greater than 0 ° C. in terms of the saturation temperature (for example, about 0.8 MPa for the R410A refrigerant). The opening degree of the flow rate adjusting device 32b is controlled so as to be constant. That is, the control device 50 has a saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b greater than a pressure (for example, about 0.8 MPa for the R410A refrigerant) that is greater than 0 ° C. in terms of saturation temperature. In this manner, the opening degree of the flow rate adjusting device 32b is controlled.

Completion of defrosting of the heat source side heat exchanger 12b is determined, for example, that the frost has melted when a predetermined time elapses or when the temperature of the third temperature sensor 48b becomes a predetermined value or higher (for example, 5 ° C.). do it. It is assumed that the predetermined time is set to be equal to or longer than the time required until all of the frost is melted, assuming that the entire heat source side heat exchanger 12b has been frosted without any gap and injecting a part of the high-temperature / high-pressure refrigerant. Good.

When the second opening / closing device 35 is maintained in the open state by the control device 50, the high-temperature / high-pressure gas refrigerant branched from the discharge side of the compressor 10 flows through the second gas bypass pipe 7, and the second The low-temperature and low-pressure gas refrigerant that has flowed out of the heat source side heat exchanger 12 a is joined via the switchgear 35 and flows into the accumulator 13. The refrigerant that has flowed into the accumulator 13 evaporates the liquid refrigerant that remains in the accumulator 13. Therefore, the amount of the gas refrigerant flowing out from the accumulator 13 can be increased, and the density of the low-pressure gas refrigerant can be increased. Therefore, the pressure of the low-pressure gas refrigerant increases, and the pressure of the low-pressure gas refrigerant can be maintained in a state higher than the first predetermined value (for example, about 0.3 MPa for the R410A refrigerant).

When the pressure of the low-pressure gas refrigerant is equal to or lower than a first predetermined value (for example, about 0.3 MPa or less for the R410A refrigerant), the density of the low-pressure gas refrigerant is reduced and the amount of refrigerant discharged from the compressor 10 is reduced. However, this leads to a decrease in heating capacity and defrosting capacity. However, according to the air conditioner 100, by using the second gas bypass pipe 7, the amount of the gas refrigerant flowing out from the accumulator 13 can be increased and the pressure of the low-pressure gas refrigerant can be increased. Therefore, the fall of the refrigerant | coolant amount discharged from the compressor 10 can be suppressed, and it becomes possible to suppress the reduction of a heating capability and a defrosting capability.

In the defrosting operation mode in the case where the outdoor air temperature detected by the second temperature sensor 45 is equal to or lower than a second predetermined value (for example, 0 ° C. or lower), the outdoor air temperature decreases and the influence of frost formation Thereby, the refrigerant | coolant pressure in the heat source side heat exchanger 12a currently used as an evaporator falls. Therefore, the refrigerant temperature in the heat source side heat exchanger 12a reaches about −27 ° C. (saturation pressure is about 0.3 MPa) in terms of saturation temperature, and the pressure of the low-pressure gas refrigerant in the suction portion of the compressor 10 is There is a possibility of reaching a predetermined value of 1 (for example, about 0.3 MPa with R410A refrigerant). Therefore, even when the outdoor air temperature is equal to or lower than the second predetermined value (for example, 0 ° C. or lower), the controller 50 maintains the second opening / closing device 35 in the open state, thereby discharging the compressor 10 from the compressor 10. Since the fall of the refrigerant | coolant amount which can be suppressed can be reduced, the reduction of heating capability and defrosting capability can be suppressed.

Furthermore, by supplying the refrigerant staying in the accumulator 13 to the suction portion of the compressor 10, the compressor 10 sucks the gas refrigerant having a higher density than before the second opening / closing device 35 is opened. Therefore, the circulation amount of the refrigerant discharged from the compressor 10 can be increased.

In this way, by increasing the refrigerant circulation amount discharged from the compressor 10, a large amount of gas refrigerant to be supplied from the second gas bypass pipe 7 to the accumulator 13 is secured, and a large amount of refrigerant is introduced into the heat source side heat exchanger 12 b. It becomes possible to supply a refrigerant. Therefore, the saturation pressure of the two-phase refrigerant in the heat source side heat exchanger 12b is faster than the case where the high-temperature / high-pressure gas refrigerant does not flow into the accumulator 13 via the second gas bypass pipe 7 and the second opening / closing device 35, It becomes possible to make it larger than 0 ° C. in terms of saturation temperature. Therefore, according to the air conditioner 100, since the temperature difference between the frost and the refrigerant necessary for melting the frost can be increased more quickly, the defrosting time can be shortened.

When defrosting of the heat source side heat exchanger 12b is performed after the defrosting of the heat source side heat exchanger 12b is completed, the alphabet a in the description of the defrosting operation of the heat source side heat exchanger 12b is used. It becomes the operation | movement which replaced b. That is, the open / close states of the first switchgear 30a, the first switchgear 30b, the third switchgear 31a, and the third switchgear 31b are reversed, and the refrigerant flows between the heat source side heat exchanger 12a and the heat source side heat exchanger 12b. Will be replaced. Further, the flow rate adjusting device 32b is fully opened, and the opening degree of the flow rate adjusting device 32a is controlled.

Thus, in the defrosting operation mode of the heat source side heat exchanger 12, the saturation temperature of the refrigerant in the heat source side heat exchanger 12 serving as a condenser is set to a medium pressure (for example, higher than 0 ° C., which is higher than the frost temperature). R410A refrigerant is about 0.8 MPa or more). For this reason, according to the air conditioning apparatus 100, since the two-phase area (latent heat) of a refrigerant | coolant can be utilized, it can defrost efficiently with little refrigerant | coolant circulation amount, and the fall of the indoor heating capability is reduced. It can be suppressed and the room can be kept comfortable.

And by implementing such a defrosting operation mode, the air conditioning apparatus 100 can defrost the heat source side heat exchanger 12a and the heat source side heat exchanger 12b while continuing the heating operation. Moreover, the defrost of the heat source side heat exchanger 12b located in the lower side of the housing | casing of the outdoor unit 1 is implemented, and the defrost of the heat source side heat exchanger 12a located in the upper side is implemented after that. For this reason, it is possible to prevent the water melted by the defrosting of the heat source side heat exchanger 12a from being re-frozen in the lower heat source side heat exchanger 12b that has not yet been defrosted. Frost can be done.

FIG. 7 shows a change in the heating capacity with respect to the saturation temperature in the heat source side heat exchanger 12 which is a defrost target heat exchanger. From FIG. 7, when the saturation temperature in the heat source side heat exchanger 12 becomes higher than 10 ° C., the refrigerant is excessively retained in the heat source side heat exchanger 12. As a result, the liquid refrigerant staying in the accumulator 13 disappears, the entire refrigeration cycle falls short of the refrigerant, and the heating capacity is reduced. Therefore, in order to eliminate the refrigerant shortage due to excessive retention of the refrigerant in the heat source side heat exchanger 12, the saturation temperature in the heat source side heat exchanger 12 is preferably in the range of 0 ° C to 10 ° C.

FIG. 8 is a flowchart showing a control operation when operating the second opening / closing device 35 when the air-conditioning apparatus 100 is in the defrosting operation mode. With reference to FIG. 8, operation | movement of the control apparatus 50 at the time of operating the 2nd opening / closing apparatus 35 at the time of a defrost operation mode is demonstrated.

(CT1)
When the detection result of the third temperature sensor 48a and the third temperature sensor 48b is equal to or lower than a predetermined value (for example, about −10 ° C. or lower) in the heating operation mode, the control device 50 performs heat source side heat exchanger 12a and heat source side heat exchange. It determines with the predetermined amount of frost having generate | occur | produced in the fin of the container 12b, performs a defrost operation mode, and transfers to CT2.

(CT2)
The control device 50 determines whether or not the outdoor air temperature detected by the second temperature sensor 45 is equal to or higher than a predetermined value (for example, 0 ° C.). This predetermined value corresponds to the second predetermined value.
If the value detected by the second temperature sensor 45 is greater than or equal to the predetermined value, the process proceeds to CT3.
If the value detected by the second temperature sensor 45 is not equal to or greater than the predetermined value, the process proceeds to CT4.

(CT3)
The control device 50 determines whether or not the pressure substantially equal to the refrigerant pressure in the suction portion of the compressor 10 detected by the second pressure sensor 42 is equal to or higher than a predetermined value (for example, 0.3 MPa or higher for the R410A refrigerant). To do. This predetermined value corresponds to the first predetermined value.
If the value detected by the second pressure sensor 42 is greater than or equal to the predetermined value, the process proceeds to CT5.
If the value detected by the second pressure sensor 42 is not equal to or greater than the predetermined value, the process proceeds to CT4.

(CT4)
The control device 50 opens the second opening / closing device 35, branches the high-temperature / high-pressure gas refrigerant discharged from the compressor 10, and passes through the second gas bypass pipe 7 and the second opening / closing device 35 to accumulate the accumulator 13. To flow into. As a result, the liquid refrigerant staying in the accumulator 13 is evaporated, the amount of the gas refrigerant flowing out of the accumulator 13 is increased, and the pressure of the low-pressure gas refrigerant can be increased.
The control device 50 proceeds to CT6 after opening the second opening / closing device 35.

(CT5)
The control device 50 closes the second opening / closing device 35, branches from the discharge side of the compressor 10, and flows into the accumulator 13 via the second gas bypass pipe 7 and the second opening / closing device 35. Block the refrigerant flow path.
After closing the second opening / closing device 35, the control device 50 proceeds to CT6.

(CT6)
The control device 50 determines whether or not the defrosting operation mode has ended.
If the defrosting operation mode has not ended, the process proceeds to CT2.
When the defrosting operation mode is completed, the process proceeds to CT7.

(CT7)
When the defrosting operation mode is completed, the control device 50 closes the second opening / closing device 35, branches off from the discharge side of the compressor 10, and passes through the second gas bypass pipe 7 and the second opening / closing device 35. Thus, the flow path of the high-temperature and high-pressure gas refrigerant flowing into the accumulator 13 is blocked.
The control device 50 shifts to the heating only operation mode after closing the second opening / closing device 35.

In CT3 in FIG. 8, the pressure substantially equal to the refrigerant pressure in the suction portion of the compressor 10 detected by the second pressure sensor 42 is set to about 0.3 MPa with the R410A refrigerant, but this is not limitative. Is not to be done. That is, a temperature difference of a predetermined value or more (for example, 10 ° C. or more) between the room temperature and the saturation temperature at the pressure in the load-side heat exchanger 21 so as not to give the user an unpleasant feeling due to cold air depending on the operating state. Can be ensured, the first predetermined value may be set smaller than 0.3 MPa. The second pressure sensor 42 is not limited to the pressure sensor, and is provided with a temperature sensor such as a thermistor. The control device 50 calculates the saturation pressure based on the detected value of the temperature sensor, and uses the saturation pressure. You may make it do.

Moreover, although the 2nd opening / closing device 35 has shown the example opened according to the detection result of the refrigerant | coolant amount decrease detection means at the time of a defrost, not only this but each opening / closing device at the time of defrost operation mode start, and flow volume At the time of switching of the adjusting device, it is predicted that the refrigerant in the refrigerant circuit will be insufficient, and therefore the second opening / closing device 35 may be opened together with the switching timing. By doing in this way, a refrigerant | coolant can be supplied to the heat source side heat exchanger 12 used as a defrost object faster, and defrost time can be shortened.

Further, when the pressure approximately equal to the refrigerant pressure in the suction portion of the compressor 10 detected by the second pressure sensor 42 is equal to or higher than a first predetermined value (for example, 0.3 MPa or higher for the R410A refrigerant), the second Although the opening / closing device 35 is shown as being closed, the present invention is not limited to this. For example, the increase in the pressure of the refrigerant in the suction portion of the compressor 10 in the defrosting operation mode may be predicted in advance by a test or the like, and may be closed after a predetermined time has elapsed. By doing in this way, even when the 2nd pressure sensor 42 fails, it can prevent supplying the refrigerant | coolant which has accumulated in the accumulator 13 excessively in a refrigerant circuit. That is, it is possible to prevent the high-temperature and high-pressure gas refrigerant branched from the discharge side of the compressor 10 from being bypassed unnecessarily, and to suppress a decrease in heating capacity.

Further, the time for keeping the second opening / closing device 35 open may be different depending on the outside air temperature. The temperature difference between the outside air and the refrigerant in the heat source side heat exchanger 12 is obtained when the heat source side heat exchanger 12 used as an evaporator obtains a heat exchange amount equal to or higher than that in the low outside air during high outside air. However, if it is substantially the same between high outside air and low outside air, the pressure of the refrigerant in the heat source side heat exchanger 12 increases, and the pressure of the refrigerant in the suction portion of the compressor 10 also increases. Therefore, the circulation amount of the refrigerant in the refrigerant circuit is large, and the second opening / closing device 35 is opened, and the refrigerant remaining in the accumulator 13 is sufficiently defrosted and heated even if the amount of refrigerant supplied into the refrigerant circuit is small. You can drive. Therefore, when the outside air is high, the time for opening the second opening / closing device 35 can be set short.

Conversely, when the outside air is low, the pressure of the refrigerant in the heat source side heat exchanger 12 decreases, and the pressure of the refrigerant in the suction portion of the compressor 10 also decreases. Therefore, the circulation amount of the refrigerant in the refrigerant circuit is small, and a large amount of the refrigerant staying in the accumulator 13 is required to be supplied into the refrigerant circuit, and the time for opening the second opening / closing device 35 is set long. There is a need.
That is, by setting the time for opening the second opening / closing device 35 according to the change in the outside air temperature, the high-temperature and high-pressure gas refrigerant branched from the discharge side of the compressor 10 is wasted, particularly when the outside air is high. Bypassing can be prevented and a decrease in heating capacity can be suppressed.

FIG. 9 shows a change in saturation temperature in terms of the pressure in the load-side heat exchanger 21 when the flow rate of the high-temperature and high-pressure gas refrigerant flowing into the accumulator 13 during the defrost mode of the air conditioner 100 is changed. FIG. In FIG. 9, when the outdoor air temperature is about 0 ° C. and the indoor air temperature is about 20 ° C., the load-side heat exchange when the flow rate of the high-temperature and high-pressure gas refrigerant flowing into the accumulator 13 in the defrosting operation mode is changed. The saturation temperature change which converted the pressure in the vessel 21 is shown. Further, in FIG. 9, the flow rate of the high-temperature and high-pressure gas refrigerant flowing into the accumulator 13 from the pipe whose horizontal axis is located at the discharge portion of the compressor 10 via the second gas bypass pipe 7 is discharged from the compressor 10. A value obtained by dividing all the high-temperature and high-pressure gas refrigerants (hereinafter referred to as gas refrigerant flow ratio), and the vertical axis represents the saturation temperature obtained by converting the pressure in the load-side heat exchanger 21.

From FIG. 9, in order to supply the refrigerant having an average refrigerant density of about 600 (kg / m ³ ) or more from the accumulator 13 to the heat source side heat exchanger 12 to be defrosted more quickly, the high temperature / high pressure flowing into the accumulator 13 is obtained. It can be seen that it is better to increase the flow rate of the gas refrigerant (shift to the right of the horizontal axis in FIG. 9). On the other hand, it can be seen that the saturation temperature obtained by converting the pressure in the load-side heat exchanger 21 decreases accordingly (shifted downward in the vertical axis in FIG. 9). Therefore, in order to keep the saturation temperature converted to the pressure in the load-side heat exchanger 21 at 30 ° C. or higher so that a temperature difference of 10 ° C. or more from the indoor air temperature of about 20 ° C. can be secured, the gas refrigerant flow rate ratio is set to 0. Must be set to less than 65. Therefore, the size of the second opening / closing device 35 may be a valve having a size that satisfies the gas refrigerant flow rate ratio of less than 0.65.

(Modified version of gas flow into the accumulator 13)
FIG. 10 is a schematic circuit configuration diagram illustrating another example of the circuit configuration of the air-conditioning apparatus 100. As shown in FIG. 10, the other end of the second gas bypass pipe 7 may be connected to the accumulator 13. According to such a configuration, the high-temperature / high-pressure gas refrigerant discharged from the compressor 10 is branched and directly flows into the accumulator 13 via the second gas bypass pipe 7 and the second opening / closing device 35. It becomes possible.

When the other end of the second gas bypass pipe 7 is connected to the refrigerant pipe 3 between the refrigerant flow switching device 11 and the accumulator 13, the high-temperature and high-pressure gas refrigerant branched from the discharge side of the compressor 10 evaporates. The heat energy is reduced by dissipating heat to the low-temperature, low-pressure gas or two-phase refrigerant that has flowed from the heat source side heat exchanger 12 that is a heat exchanger. Furthermore, when it flows into the accumulator 13, heat is exchanged only with the liquid surface located above the liquid refrigerant staying in the accumulator 13.

Therefore, by adopting a circuit configuration as shown in FIG. 10, heat exchange can be performed efficiently between the gas refrigerant that has flowed into the accumulator 13 and the liquid refrigerant that has accumulated in the accumulator 13. Therefore, the refrigerant staying in the accumulator 13 is defrosted faster than the case where the high-temperature / high-pressure gas refrigerant branched from the discharge side of the compressor 10 is caused to flow into the piping of the inflow portion of the accumulator 13. It becomes possible to supply to a certain heat source side heat exchanger 12, and defrosting can be performed more quickly. Therefore, the indoor heating capacity can be further prevented from being lowered, and the room can be kept comfortable.

Embodiment 2. FIG.
FIG. 11 is a schematic circuit configuration diagram showing an example of a circuit configuration of the air-conditioning apparatus 200 according to Embodiment 2 of the present invention.
Based on FIG. 11, the detailed structure of the air conditioning apparatus 200 is demonstrated.
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 description thereof will be omitted. Moreover, in FIG. 11, the flow direction of the refrigerant | coolant in case defrosting of the heat source side heat exchanger 12b is shown with the solid line arrow.

As shown in FIG. 11, in the air conditioner 200, a fourth opening / closing device 33 a that newly blocks the refrigerant flow path of the heat source side heat exchanger 12 a to the pipe on the load side expansion device 22 side of the heat source side heat exchanger 12 a. Is installed. Similarly, in the air conditioner 200, a fourth opening / closing device 33b that blocks the refrigerant flow path of the heat source side heat exchanger 12b is installed in the piping on the load side expansion device 22 side of the heat source side heat exchanger 12b.

Furthermore, in the air conditioner 200, the refrigerant bypass pipe 6 is installed. One end of the refrigerant bypass pipe 6 is connected to the refrigerant pipe 3 between each of the heat source side heat exchanger 12a and the heat source side heat exchanger 12b and each of the third switchgear 31a and the third switchgear 31b. . The other end of the refrigerant bypass pipe 6 is connected to a flow path between each of the fourth opening / closing device 33 a and the fourth opening / closing device 33 b and the load side expansion device 22. The refrigerant bypass pipe 6 allows the refrigerant in the heat source side heat exchanger 12 serving as a condenser to flow into the refrigerant pipe 3 in the defrosting operation mode.

Further, the fifth switching device 34a and the fifth switching device 34b for switching the refrigerant flow path of the refrigerant bypass pipe 6 are connected between the heat source side heat exchanger 12 and the third switching device 31 each corresponding to one end. The refrigerant bypass pipe 6 is installed. Then, the flow rate adjusting device 32b (or the flow rate), which is a throttle device whose opening degree (opening area) is changed to adjust the pressure of the refrigerant in the heat source side heat exchanger 12 to the other end side of the refrigerant bypass pipe 6. One of the adjusting devices 32a) is installed.

The fourth opening / closing device 33a is a low-temperature two-phase flow that flows into the outdoor unit 1 from the indoor unit 2 through the refrigerant main pipe 4 when the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode. The flow path of the refrigerant is blocked so that the refrigerant does not flow into the heat source side heat exchanger 12a.
The fourth switchgear 33b is a low-temperature two-phase flow that flows from the indoor unit 2 into the outdoor unit 1 through the refrigerant main pipe 4 when the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode. The refrigerant flow path is blocked so that the refrigerant does not flow into the heat source side heat exchanger 12b.

The fourth opening / closing device 33a and the fourth opening / closing device 33b may be configured to be capable of opening / closing a refrigerant flow path, such as a two-way valve, an electromagnetic valve, or an electronic expansion valve.
In the following description, the fourth switchgear 33a and the fourth switchgear 33b may be collectively referred to as the fourth switchgear 33.

When the heat source side heat exchanger 12a operates as a condenser during the defrosting operation mode, the fifth opening / closing device 34a removes the refrigerant flowing out of the heat source side heat exchanger 12a from the flow rate adjusting device 32b (or the flow rate adjusting device). It is made to flow into the refrigerant pipe 3 via 32a).
When the heat source side heat exchanger 12b operates as a condenser during the defrosting operation mode, the fifth opening / closing device 34b removes the refrigerant flowing out of the heat source side heat exchanger 12a from the flow rate adjustment device 32b (or the flow rate adjustment device). It is made to flow into the refrigerant pipe 3 via 32a).

The fifth opening / closing device 34a and the fifth opening / closing device 34b may be configured to be capable of opening and closing a refrigerant flow path, such as a two-way valve, an electromagnetic valve, and an electronic expansion valve.
In the following description, the fifth opening / closing device 34a and the fifth opening / closing device 34b may be collectively referred to as the fifth opening / closing device 34.

The other end of the first gas bypass pipe 5 branched into two branches is connected to the refrigerant pipe 3 between the heat source side heat exchanger 12a and the fourth switchgear 33a, and the other is connected to the heat source side heat exchanger. It connects to the refrigerant | coolant piping 3 between 12b and the 4th switchgear 33b.

And the 3rd temperature sensor 48a is provided in the refrigerant | coolant piping 3 between the heat source side heat exchanger 12a and the 3rd switchgear 31a, and the 3rd temperature sensor 48b is the heat source side heat exchanger 12b and 3rd. It is provided in the refrigerant pipe 3 between the switchgear 31b.
The third temperature sensor 48a measures the temperature of the refrigerant flowing out from the heat source side heat exchanger 12a operating as an evaporator or the refrigerant flowing out from the heat source side heat exchanger 12a operating as a condenser. The third temperature sensor 48b measures the temperature of the refrigerant flowing in from the heat source side heat exchanger 12b operating as an evaporator or the refrigerant flowing out of the heat source side heat exchanger 12b operating as a condenser.

In addition, since the other structure is the same as that of the air conditioning apparatus 100 which concerns on Embodiment 1, description is abbreviate | omitted. 6 to 9 used in the description of the first embodiment also applies to the air conditioner 200.

When the air-conditioning apparatus 200 is in the cooling only operation mode or the heating only operation mode, the fourth opening / closing device 33a and the fourth opening / closing device 33b are open, and the fifth opening / closing device 34a and the fifth opening / closing device 34b are closed. Since the other operations of the switchgear and the flow of the refrigerant are the same as those of the air conditioner 100 according to Embodiment 1, the description thereof is omitted.

[Defrost operation mode]
Even in the defrosting operation mode of the air conditioner 200, the heat source side heat exchanger 12b located on the lower side in the casing of the outdoor unit 1 is defrosted, and then positioned on the upper side in the casing of the outdoor unit 1. Defrosting of the heat source side heat exchanger 12a is performed.
The conditions for starting the defrosting operation mode are the same as those of the air conditioner 100 according to Embodiment 1.

(Defrosting of heat source side heat exchanger 12b)
In the defrosting operation mode, the refrigerant flow switching device 11 is maintained in the state indicated by the solid line in FIG.
Further, in the defrosting operation mode, the first opening / closing device 30, the second opening / closing device 35, the third opening / closing device 31, the fourth opening / closing device 33, and the fifth opening / closing device when the heat source side heat exchanger 12b is to be defrosted. 34 and the state of the flow rate adjusting device 32 are as follows.
Both are controlled by the control device 50.

The first opening / closing device 30b is switched to the open state and allows the refrigerant to pass therethrough.
The third opening / closing device 31b is switched to the closed state and blocks the refrigerant.
The fourth opening / closing device 33b is switched to the closed state and blocks the refrigerant.
The fifth opening / closing device 34b is switched to the open state and allows the refrigerant to pass therethrough.
The first opening / closing device 30a is maintained in a closed state and blocks the refrigerant.
The third opening / closing device 31a is maintained in the open state and allows the refrigerant to pass therethrough.
The fourth opening / closing device 33a is switched to the open state and allows the refrigerant to pass therethrough.
The fifth opening / closing device 34a is switched to the closed state and blocks the refrigerant.

The flow rate adjusting device 32b (or the flow rate adjusting device 32a) is configured such that the saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b, which is the “defrosting refrigerant amount decrease detecting means”, is 0 ° C. in terms of saturation temperature. The opening degree is controlled such that a preset pressure (for example, about 0.8 MPa for the R410A refrigerant) that becomes larger is constant.

When the outdoor air temperature detected by the second temperature sensor 45 is equal to or lower than a second predetermined value (for example, 0 ° C. or lower), the second opening / closing device 35 or the compressor 10 detected by the second pressure sensor 42 is used. When the pressure of the suction part is less than a first predetermined value (for example, about 0.3 MPa or less with R410A refrigerant), when one or both of them are satisfied, the open state is maintained and the refrigerant passes. Let
The second temperature sensor 45, the second pressure sensor 42, and the third temperature sensor 48b correspond to the “defrosting refrigerant amount decrease detecting means” of the present invention.

The refrigerant flow during the defrosting operation mode will be described in detail.
When the compressor 10 is driven, the low-temperature and low-pressure refrigerant is compressed and discharged as a high-temperature and high-pressure gas refrigerant.
A part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows through the first gas bypass pipe 5 and is depressurized by the first switchgear 30b so as to become higher than 0 ° C. in terms of saturation temperature, and the medium pressure -It becomes a high-temperature gas refrigerant and flows into the heat source side heat exchanger 12b. The medium-pressure and high-temperature gas refrigerant that has flowed into the heat source side heat exchanger 12b becomes a two-phase refrigerant having a low intermediate pressure or a medium pressure refrigerant while melting frost adhering to the heat source side heat exchanger 12b. And passes through the fifth opening / closing device 34b. The refrigerant that has passed through the fifth opening / closing device 34b is depressurized by the flow rate adjusting device 32b (or the flow rate adjusting device 32a) and flows into the outdoor unit 1 from the indoor unit 2 into the outdoor unit 1 or a low-drying two-phase refrigerant having a low intermediate pressure or low temperature, or The liquid refrigerant merges on the upstream side of the fourth opening / closing device 33a.

Most of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the refrigerant flow switching device 11. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the indoor unit 2 through the refrigerant main pipe 4, and dissipates heat to the indoor air in the load-side heat exchanger 21, thereby heating the indoor air. It becomes a liquid refrigerant. The liquid refrigerant that has flowed out of the load-side heat exchanger 21 is expanded by the load-side expansion device 22, becomes a low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant, and flows into the outdoor unit 1 again through the refrigerant main pipe 4.

The low-temperature / medium-pressure two-phase refrigerant or liquid refrigerant flowing into the outdoor unit 1 merges with the refrigerant from the flow rate adjusting device 32b (or the flow rate adjusting device 32a) upstream of the fourth opening / closing device 33a to perform heat source side heat exchange. Flow into the vessel 12a. The refrigerant flowing into the heat source side heat exchanger 12a absorbs heat from the outdoor air and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant that has flowed out of the heat source side heat exchanger 12a is again sucked into the compressor 10 via the third opening / closing device 31a, the refrigerant flow switching device 11, and the accumulator 13.

The control device 50 has a preset pressure at which the saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b is greater than 0 ° C. in terms of the saturation temperature (for example, about 0.8 MPa for the R410A refrigerant). The opening degree of the flow rate adjusting device 32b (or the flow rate adjusting device 32a) is controlled so as to be constant. That is, the controller 50 adjusts the flow rate adjusting device 32b (or the flow rate adjusting device 32a) so that the saturation pressure of the two-phase refrigerant calculated from the detection result of the third temperature sensor 48b is greater than 0 ° C. in terms of saturation temperature. ) Is controlled.

Other operations in the defrosting operation mode are the same as those of the air conditioner 100 according to the first embodiment. That is, even when the second opening / closing device 35 is maintained in the open state by the control device 50, the high-temperature / high-pressure gas refrigerant branched from the discharge side of the compressor 10 is caused to flow into the accumulator 13 and stay in the accumulator 13. The refrigerant is supplied to the suction portion of the compressor 10. By carrying out like this, according to the air conditioning apparatus 200, the effect similar to the air conditioning apparatus 100 which concerns on Embodiment 1 is acquired, and the reduction of a room heating capability and a defrosting capability can be suppressed.

The operation of the control device 50 when operating the second opening / closing device 35 is also the same as that of the air conditioner 100 according to the first embodiment, and is therefore omitted.

Further, for example, when the heat source side heat exchanger 12b is configured by two rows of heat exchangers and used as an evaporator, the heat source side heat exchanger 12b is positioned in the first row on the outdoor air inlet side of the heat source side heat exchanger 12b. Most of the outdoor air is dehumidified by the fins located in the first row, which is the side flowing into the heat source side heat exchanger 12b. That is, the frost formation amount of the fins located in the first row on the side flowing into the heat source side heat exchanger 12b is large, and the frost formation amount of the fins located in the second row is small.

Therefore, unlike the air conditioner 100 according to Embodiment 1, a part of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 is exchanged with the heat source side heat exchanger 12b serving as a condenser. By flowing in the same direction as the flow path when the vessel 12b is used as an evaporator, a two-phase refrigerant having a larger thermal energy can be caused to flow into the first row having a larger amount of frost formation. Therefore, in the air conditioning apparatus 200, it becomes possible to perform defrosting more efficiently than the air conditioning apparatus 100 according to Embodiment 1, the defrosting time can be shortened, and the reduction in indoor heating capacity can be further suppressed. .

When defrosting of the heat source side heat exchanger 12b is performed after the defrosting of the heat source side heat exchanger 12b is completed, the alphabet a in the description of the defrosting operation of the heat source side heat exchanger 12b is used. It becomes the operation | movement which replaced b. That is, the first switchgear 30a, the first switchgear 30b, the third switchgear 31a, the third switchgear 31b, the fourth switchgear 33a, the fourth switchgear 33b, the fifth switchgear 34a, and the fifth switchgear 34b. The open / close state is reversed, and the refrigerant flows in the heat source side heat exchanger 12a and the heat source side heat exchanger 12b are switched.

Thus, in the defrosting operation mode of the heat source side heat exchanger 12, the saturation temperature of the refrigerant in the heat source side heat exchanger 12 serving as a condenser is set to a medium pressure (for example, higher than 0 ° C., which is higher than the frost temperature). R410A refrigerant is about 0.8 MPa or more). For this reason, according to the air conditioning apparatus 200, since the two-phase region (latent heat) of the refrigerant can be used, defrosting can be efficiently performed with a small amount of refrigerant circulation, and the indoor heating capacity can be reduced. It can be suppressed and the room can be kept comfortable.

And by implementing such a defrosting operation mode, the air conditioning apparatus 200 can defrost the heat source side heat exchanger 12a and the heat source side heat exchanger 12b while continuing the heating operation. Moreover, the defrost of the heat source side heat exchanger 12b located in the lower side of the housing | casing of the outdoor unit 1 is implemented, and the defrost of the heat source side heat exchanger 12a located in the upper side is implemented after that. For this reason, it is possible to prevent the water melted by the defrosting of the heat source side heat exchanger 12a from being re-frozen in the lower heat source side heat exchanger 12b that has not yet been defrosted. Frost can be done.

In the above description, in the air-conditioning apparatus 200 according to Embodiment 2, the high-temperature / high-pressure gas refrigerant branched from the discharge side of the compressor 10 is caused to flow into the piping of the inflow portion of the accumulator 13. However, it is not limited to this. For example, as in FIG. 10 in the air-conditioning apparatus 100 according to Embodiment 1, the high-temperature / high-pressure gas refrigerant branched from the discharge side of the compressor 10 is supplied to the second gas bypass pipe 7 and the second opening / closing device 35. Therefore, a circuit configuration that flows directly into the accumulator 13 may be adopted. With such a configuration, it is possible to obtain the same effects as those of the air conditioner 100 according to Embodiment 1, efficiently perform defrosting, suppress a decrease in indoor heating capacity, It becomes possible to keep it comfortable.

[Refrigerant]
As the heat source side refrigerant applied to the air conditioner 100 according to the first embodiment and the air conditioner 200 according to the second embodiment, non-flammable refrigerants such as R410A, R407C, and R22, HFO1234yf, HFO1234ze (E), R32, HC, a refrigerant containing R32 and HFO1234yf, a refrigerant exhibiting slight flammability such as a refrigerant using a refrigerant mixture containing at least one of the aforementioned refrigerants, a highly flammable refrigerant such as propane (R290), CO ₂ (R744) A refrigerant that operates supercritically on the high-pressure side such as) can be used as the heat-source-side refrigerant.

[First switchgear]
As the first opening / closing device 30a and the first opening / closing device 30b of the air-conditioning apparatus 100 according to Embodiment 1 and the air-conditioning apparatus 200 according to Embodiment 2, an example in which an electromagnetic valve is used has been described. In addition, you may use the valve which can change an opening degree like the electronic expansion valve as the 1st opening / closing device 30a and the 1st opening / closing device 30b.

[Second switchgear]
Although the example which uses a solenoid valve was demonstrated as the 2nd opening / closing device 35 of the air conditioning apparatus 100 which concerns on Embodiment 1, and the air conditioning apparatus 200 which concerns on Embodiment 2, it is electronic expansion other than a solenoid valve. A valve whose opening degree can be varied, such as a valve, may be used as the second opening / closing device 35. In the air conditioner 100 according to the first embodiment and the air conditioner 200 according to the second embodiment, an example in which one second opening / closing device 35 is used has been described. However, a plurality of electromagnetic valves are arranged in parallel. Even in this case, the same effects as those of the first and second embodiments can be obtained.

[Third switchgear]
As the third opening / closing device 31a and the third opening / closing device 31b of the air-conditioning apparatus 100 according to Embodiment 1 and the air-conditioning apparatus 200 according to Embodiment 2, an example in which an electromagnetic valve is used has been described. In addition, a valve whose opening degree can be varied, such as an electronic expansion valve, may be used as the third opening / closing device 31a and the third opening / closing device 31b.

[Flow control device]
Although the air conditioner 100 according to the first embodiment and the flow rate adjusting device 32a and the flow rate adjusting device 32b of the air conditioner 200 according to the second embodiment are the throttle devices that can change the opening degree (opening area), Any device that can change the opening area of the road may be used. For example, the expansion device may be an electronic expansion valve that is driven by a stepping motor, or a plurality of small electromagnetic valves arranged in parallel and switched to change the opening area.

Moreover, although both the air conditioner 100a which concerns on Embodiment 1, and the flow volume adjustment apparatus 32a of the air conditioning apparatus 200 which concerns on Embodiment 2, and the flow volume adjustment apparatus 32b are set as the apparatus which can change the opening area of a flow path. For example, the flow rate adjusting device 32a may be a device capable of changing the opening area of the flow path, and the flow rate adjusting device 32b may be configured by arranging a plurality of small solenoid valves in parallel. The same effect as 2 is obtained.

[Fourth switchgear]
Although the example which uses a solenoid valve was demonstrated as the 4th opening / closing apparatus 33 of the air conditioning apparatus 200 which concerns on Embodiment 2, the valve which can vary an opening degree like an electronic expansion valve other than a solenoid valve. The fourth opening / closing device 33 may be used.

[Fifth switchgear]
Although the example which uses a solenoid valve was demonstrated as the 5th opening / closing apparatus 34 of the air conditioning apparatus 200 which concerns on Embodiment 2, in addition to a solenoid valve, the valve which can change an opening degree like an electronic expansion valve is used. You may use as a 5th switchgear.

When each opening / closing device uses an electronic expansion valve or the like that can change the opening degree (opening area), opening each opening / closing device means that each opening / closing device is fully open or close to full opening. To close each opening / closing device means to make each opening / closing device fully closed or close to the fully closed position. The same applies to the flow rate adjustment device. To open means to open the flow rate adjustment device to the full open or close to full open, and to close the flow rate adjustment device, to fully close or fully close the flow rate adjustment device. The opening degree is close to 0, that is, the state is such that the refrigerant hardly flows.

[Heat source side heat exchanger]
The heat source side heat exchanger 12a and the heat source side heat exchanger 12b of the air conditioner 100 according to the first embodiment and the air conditioner 200 according to the second embodiment are arranged in the step direction (the fins face the same direction). Although the example which is located in two steps in the vertical direction) has been described, the present invention is not limited to this. For example, as described above, the heat source side heat exchanger 12 may be configured to have a plurality of units such as three or more in the step direction (vertical direction in which each fin faces the same direction). Moreover, the arrangement of the plurality of heat source side heat exchangers 12 is not limited to the upper and lower sides, and may be arranged in the left and right direction and the front and rear direction.

The air-conditioning apparatus 100 according to Embodiment 1 and the air-conditioning apparatus 200 according to Embodiment 2 have been described using the air-conditioning apparatus capable of switching between cooling and heating operations as an example. The present invention can also be applied to an air conditioner having a possible circuit configuration. Moreover, it is applicable also to the air conditioning apparatus which abbreviate | omits the refrigerant | coolant flow path switching apparatus 11, and implements only a heating only operation mode and a defrost operation mode. In addition, a heating circuit refers to the refrigerant circuit structure of the air conditioning apparatus 100 and the air conditioning apparatus 200 formed at the time of heating operation mode.

1 outdoor unit, 2 indoor unit, 3 refrigerant pipe, 4 refrigerant main pipe, 5 first gas bypass pipe, 6 refrigerant bypass pipe, 7 second gas bypass pipe, 10 compressor, 11 refrigerant flow switching device, 12 heat source side heat Exchanger, 12a heat source side heat exchanger, 12b heat source side heat exchanger, 13 accumulator, 21 load side heat exchanger, 22 load side expansion device, 30 first switchgear, 30a first switchgear, 30b first switchgear , 31 3rd switchgear, 31a 3rd switchgear, 31b 3rd switchgear, 32 flow rate regulator, 32a flow rate regulator, 32b flow rate regulator, 33 4th switchgear, 33a 4th switchgear, 33b 4th switchgear Device, 34 5th switchgear, 34a 5th switchgear, 34b 5th switchgear, 35 2nd switchgear, 41 1st pressure sensor, 4 2nd pressure sensor, 43 1st temperature sensor, 44 6th temperature sensor, 45 2nd temperature sensor, 46 4th temperature sensor, 47 5th temperature sensor, 48a 3rd temperature sensor, 48b 3rd temperature sensor, 50 control device , 51 fins, 52 heat transfer tubes, 100 air conditioners, 200 air conditioners.

Claims

An air conditioner capable of simultaneously performing heating operation and defrosting operation,
A main circuit that forms at least a heating circuit by connecting a compressor, a load-side heat exchanger, a load-side expansion device, a plurality of heat-source-side heat exchangers connected in parallel to each other, and an accumulator by a refrigerant pipe;
A first gas bypass pipe branched from the discharge side of the compressor and allowing a refrigerant to flow into the heat source side heat exchanger to be defrosted among the plurality of heat source side heat exchangers;
A second gas bypass pipe branched from the discharge side of the compressor and allowing a refrigerant to flow into the accumulator;
A plurality of first opening and closing devices that are provided in the first gas bypass pipe and perform passage or blocking of the refrigerant flowing through the first gas bypass pipe;
An air conditioner comprising: at least one second opening / closing device provided in the second gas bypass pipe and configured to pass or block the refrigerant flowing through the second gas bypass pipe.
When carrying out heating operation and defrosting operation at the same time,
The first opening / closing device causes a part of the refrigerant discharged from the compressor to flow into the heat source heat exchanger to be defrosted to function as a condenser,
The heat source side heat exchanger other than the defrost target functions as an evaporator,
2. The air conditioner according to claim 1, wherein a part of the refrigerant discharged from the compressor is caused to flow into the accumulator by the second opening / closing device in accordance with an amount of refrigerant circulating in the main circuit. .
A defrosting refrigerant amount decrease detecting means for detecting the amount of refrigerant circulating in the main circuit;
The air conditioning apparatus according to claim 1 or 2, wherein opening and closing of the second opening and closing device is controlled based on a detection result of the defrosting refrigerant amount decrease detecting means.
A refrigerant flow switching device provided on the discharge side of the compressor;
A plurality of third opening / closing devices provided between each of the plurality of heat source side heat exchangers and the refrigerant flow switching device, for passing or blocking the refrigerant flowing from the plurality of heat source side heat exchangers to the accumulator. When,
The opening degree is variable, and includes at least one flow rate adjustment device provided between the plurality of heat source side heat exchangers and the load side expansion device,
Close the third switchgear corresponding to the heat source side heat exchanger to be defrosted,
The pressure of the refrigerant flowing out of the heat source side heat exchanger to be defrosted is adjusted by the flow rate adjusting device so as to be greater than 0 ° C in terms of saturation temperature. The air conditioning apparatus according to one item.
A refrigerant flow switching device provided on the discharge side of the compressor;
A plurality of third opening / closing devices provided between each of the plurality of heat source side heat exchangers and the refrigerant flow switching device, for passing or blocking the refrigerant flowing from the plurality of heat source side heat exchangers to the accumulator. When,
A plurality of fourths which are provided between each of the plurality of heat source side heat exchangers and the load side expansion device, and pass or block the refrigerant flowing from the plurality of heat source side heat exchangers to the load side expansion device. A switchgear;
Connecting each flow path between the plurality of heat source side heat exchangers and the plurality of third switchgears and a flow path between the plurality of fourth switchgears and the load side expansion device. A refrigerant bypass pipe that causes the refrigerant flowing out from the heat source side heat exchanger to be defrosted to flow into a flow path between the plurality of fourth opening / closing devices and the load side expansion device,
A plurality of fifth opening and closing devices that are provided in the refrigerant bypass pipe corresponding to the plurality of heat source side heat exchangers, and that pass or block the refrigerant;
The opening degree is variable, and includes at least one flow rate adjusting device provided in the refrigerant bypass pipe,
The third switching device and the fourth switching device corresponding to the heat source side heat exchanger to be defrosted are closed, the first switching device and the fifth corresponding to the heat source side heat exchanger to be defrosted. Open the switchgear,
The pressure of the refrigerant flowing out of the heat source side heat exchanger to be defrosted is adjusted by the flow rate adjusting device so as to be greater than 0 ° C in terms of saturation temperature. The air conditioning apparatus according to one item.
As the defrosting refrigerant amount decrease detection means, using a pressure sensor for detecting the refrigerant pressure on the suction side of the compressor,
The subordinate to the third and third aspects, wherein the second opening / closing device is opened when a detection result of the pressure sensor becomes equal to or lower than a first predetermined value set in advance. Or the air conditioning apparatus of 5.
As the defrosting refrigerant amount decrease detection means, using a temperature sensor that detects outdoor air temperature,
The subordinate to the third and third aspects, wherein the second opening / closing device is opened when a detection result of the temperature sensor becomes equal to or lower than a second predetermined value set in advance. Or the air conditioning apparatus of 5.
As the defrosting refrigerant amount decrease detecting means, a pressure sensor for detecting the refrigerant pressure on the suction side of the compressor, and a temperature sensor for detecting the outdoor air temperature,
When the detection result of the pressure sensor is equal to or less than a first predetermined value set in advance and the detection result of the temperature sensor is equal to or less than a second predetermined value set in advance, the second opening / closing device is The air conditioner according to claim 3 or claim 4 or claim 5 dependent on claim 3, wherein the air conditioner is open.
The first predetermined value is set based on a saturation pressure at which the saturation temperature of the refrigerant used is −27 ° C. or less,
When the detection result of the pressure sensor becomes equal to or less than the first predetermined value, the second opening / closing device is opened,
The air conditioner according to claim 6, wherein the second opening / closing device is closed after the defrosting operation is completed.
The second predetermined value is set to 0 ° C. or less,
When the detection result of the temperature sensor is equal to or less than the second predetermined value, the second opening / closing device is opened,
The air conditioner according to claim 7, wherein the second opening and closing device is closed after the defrosting operation is completed.
The first predetermined value is set based on a saturation pressure at which the saturation temperature of the refrigerant used is −27 ° C. or less,
The second predetermined value is set to 0 ° C. or lower,
When the detection result of the pressure sensor is equal to or lower than the first predetermined value and the detection result of the temperature sensor is equal to or lower than the second predetermined value, the second opening / closing device is opened;
When the detection result of the pressure sensor becomes larger than the first predetermined value and the detection result of the temperature sensor becomes larger than the second predetermined value, the second opening / closing device is closed. The air conditioning apparatus according to claim 8, wherein
The second opening / closing device includes:
12. The method according to claim 1, wherein a value obtained by dividing the flow rate of the refrigerant flowing through the second gas bypass pipe by the flow rate of the refrigerant discharged from the compressor is less than 0.65. The air conditioning apparatus according to any one of claims.
The plurality of heat source side heat exchangers are arranged adjacent to each other in the vertical direction,
When carrying out heating operation and defrosting operation at the same time,
The defrosting operation is executed from the heat source side heat exchanger located on the lower side,
The air conditioning apparatus according to any one of claims 1 to 12, wherein after that, the defrosting operation of the heat source side heat exchanger located on the upper side is performed.