WO2015140951A1

WO2015140951A1 - Air conditioner

Info

Publication number: WO2015140951A1
Application number: PCT/JP2014/057466
Authority: WO
Inventors: 若本　慎一; 直史竹中; 山下　浩司; 森本　修; 博文 ▲高▼下
Original assignee: 三菱電機株式会社
Priority date: 2014-03-19
Filing date: 2014-03-19
Publication date: 2015-09-24

Abstract

A portion of refrigerant that is discharged from an injection-type compressor (1) passes through a first by-pass pipe (21) and is supplied to an outdoor heat exchanger (9b) to be defrosted by way of a first flow path switching device (A), and a portion of the refrigerant supplied to the outdoor heat exchanger (9b) to be defrosted is caused to flow to a second by-pass pipe (31) by way of a second flow path switching device (B).

Description

Air conditioner

This invention relates to an air conditioner.

In conventional air conditioners, defrosting is performed by reversing the refrigerant cycle in order to remove frost from the outdoor heat exchanger that serves as an evaporator during heating operation. However, in this defrosting operation, the heating is stopped during the defrosting operation, so the indoor comfort is impaired. Therefore, as a technology that enables heating operation and defrost operation at the same time, the outdoor heat exchanger is divided into a plurality of parallel heat exchangers, and the discharge gas from the injection compressor corresponding to each of the divided heat exchangers There is a heat pump provided with a bypass circuit for bypassing and an electromagnetic on-off valve for controlling the bypass state (for example, see Patent Document 1).

This heat pump includes an outdoor unit, an indoor unit, and a main pipe that connects them so that a refrigerant circulates, and is a multi-type air conditioner in which two indoor units are connected to one outdoor unit. Device. The outdoor unit consists of an injection compressor, a four-way valve that switches between cooling operation and heating operation, an outdoor heat exchanger connected in parallel, one end connected between the injection compressor and the four-way valve, and the other end branched and the outdoor heat A first bypass pipe connected in parallel to the pipe connected to the exchanger, a second flow path switching device for switching the refrigerant flow path to either the main pipe or the first bypass pipe, and the first bypass A third flow rate control valve that controls the flow rate of the refrigerant flowing through the pipe is provided. Thereby, a part of the refrigerant from the injection compressor is alternately flowed into each bypass circuit, and each parallel heat exchanger is alternately defrosted, thereby continuously heating without reversing the refrigeration cycle. Is possible.

In addition, there is a refrigerator in which the heat exchanger is configured as a plurality of parallel heat exchangers, includes a plurality of main compressors and sub-compressors, and injects refrigerant used for defrosting the heat exchanger into the sub-compressor ( For example, see Patent Document 2).

JP 2009-85484 A (summary) JP 2007-225271 A

However, in the technique of Patent Document 1, during the simultaneous operation of the heating operation and the defrost operation, the refrigerant in the gas-liquid two-phase state that flows out from the outdoor heat exchanger to be defrosted and the outdoor heat exchanger that performs the heating operation flow out. The mixed gas refrigerant is mixed and sucked into the injection compressor. Therefore, the injection compressor needs to raise not only the refrigerant for heating but also the refrigerant for defrosting from a low pressure to a high pressure, and there is a problem in that the efficiency of the air conditioner decreases.
The enthalpy that can be used for defrosting is only sensible heat of gas. In order to melt frost, it is necessary to flow a large amount of high-temperature and high-pressure refrigerant discharged from the injection compressor to the first bypass pipe. There is a problem that the flow rate of the refrigerant flowing through the outdoor heat exchanger that radiates heat to the outside in order to perform heating is reduced, and the heating capacity is reduced.

Further, the technique of Patent Document 2 requires a sub-compressor, and further relates to a refrigerator that can perform only refrigeration and freezing, and does not include means for switching the flow direction of the refrigerant. The heating and cooling operations required as a device cannot be performed.

The present invention has been made to solve the above-described conventional problems, and can improve energy efficiency and heating capacity in simultaneous operation of heating operation and defrost operation using a main compressor. An object is to provide an air conditioner.

The air conditioner according to the present invention is an air conditioner including a main pipe that connects the indoor unit and the outdoor unit so that the refrigerant circulates between the indoor heat exchanger and the refrigerant flowing through the indoor heat exchanger. A flow rate control valve for controlling the flow rate of the refrigerant, an injection type compressor having an injection port capable of injecting the refrigerant into the refrigerant being compressed, a refrigerant flow switching device for switching between the cooling operation and the heating operation, and a plurality of units connected in parallel The outdoor heat exchanger has a first end connected between the injection compressor and the refrigerant flow switching device, and the other end connected to one of the plurality of outdoor heat exchangers on the inlet / outlet side. The bypass pipe and one end of the bypass pipe are connected to the injection port or a pipe connected to the injection port, and the other end is connected to the other of the inlet / outlet side of the plurality of outdoor heat exchangers. A second bypass pipe being continued, the flow path of the refrigerant, a first flow path switching unit to switch to one of the main pipes or the first bypass pipe,
A second flow path switching device for switching a refrigerant flow path to either the main pipe or the second bypass pipe, and frosting of the outdoor heat exchanger of any of the plurality of outdoor heat exchangers During the defrost operation for removing the refrigerant, the first flow path switching device allows a part of the refrigerant discharged from the injection compressor to pass through the first bypass pipe, and among the plurality of outdoor heat exchangers The defrost target outdoor heat exchanger is supplied to the second flow path switching device, and a part of the refrigerant supplied to the defrost target outdoor heat exchanger is caused to flow into the second bypass pipe. .

According to the present invention, there is no need to lower the refrigerant pressure for defrosting to the suction pressure. Therefore, in the injection compressor, only the refrigerant circulating in the main circuit for heating needs to be increased from low pressure to high pressure, and the injected intermediate-pressure gas-liquid two-phase refrigerant is increased from the intermediate pressure to the high pressure. Therefore, the amount of work of the injection compressor 1 is reduced, and the effect of improving the efficiency and heating capacity of the heat pump can be obtained.

It is a figure which shows the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of the cooling only operation of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of the all heating operation of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of heating defrost simultaneous operation | movement of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the structure and operation | movement of a two-way valve with which the air conditioning apparatus which concerns on Embodiment 1 of this invention is equipped. It is a figure which shows the structure of the outdoor heat exchanger with which the air conditioning apparatus which concerns on Embodiment 1 of this invention is equipped, and the flow of a refrigerant | coolant. It is a figure which shows the relationship between the pressure of a refrigerant | coolant at the time of the cooling only operation of the air conditioning apparatus which concerns on Embodiment 1 of this invention, and enthalpy. It is a figure which shows the relationship between the pressure of a refrigerant | coolant at the time of the heating only operation of the air conditioning apparatus which concerns on Embodiment 1 of this invention, and enthalpy. It is a figure which shows the relationship between the pressure of a refrigerant | coolant at the time of heating defrost simultaneous operation of the heat pump by Embodiment 1 of this invention, and enthalpy. It is a figure which shows the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of heating defrost simultaneous operation | movement of the air conditioning apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the relationship between the pressure of a refrigerant | coolant at the time of heating defrost simultaneous operation of the heat pump by Embodiment 2 of this invention, and enthalpy.

Embodiment 1 FIG.
The first embodiment of the present invention will be described below with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same location. 1 is a diagram illustrating a refrigerant circuit of an air-conditioning apparatus according to Embodiment 1 of the present invention. Hereinafter, the air conditioner 1000 will be described with reference to FIG.

The air conditioner 1000 includes an outdoor unit 100,

indoor units

200a and 200b, and a main pipe that connects them so that a refrigerant circulates, and two indoor units are connected to one outdoor unit. Multi-type air conditioner.

The outdoor unit 100 includes an injection compressor 1, a temperature sensor 2, a four-way valve 3, a refrigerant heat exchanger 6, a second flow control valve 7 (corresponding to the outdoor flow control valve in the present invention), and a two-way valve 8a. 8b,

outdoor heat exchangers

9a and 9b, two-

way valves

10a and 10b, first bypass pipe 21, two-

way valves

22a and 22b, second bypass pipe 31, and third

flow control valves

32a and 32b (main) Corresponding to the second bypass flow control valve in the invention), the third bypass pipe 41, the fourth flow control valve 42 (corresponding to the injection flow control valve in the present invention), the first flow path switching device A, the second Two flow path switching devices B are provided. The indoor unit 200a is provided with an indoor heat exchanger 4a and a first flow control valve 5a (corresponding to the flow control valve in the present invention). The indoor unit 200b is provided with an indoor heat exchanger 4b and a first flow control valve 5b (corresponding to the flow control valve in the present invention).

The injection compressor 1 is a compressor that can inject a refrigerant into a refrigerant that is being compressed. The temperature sensor 2 measures the temperature of the refrigerant discharged from the injection compressor 1. The four-way valve 3 switches between the cooling operation and the heating operation, and corresponds to the refrigerant flow switching device of the present invention. The refrigerant heat exchanger 6 exchanges heat between the refrigerant flowing through the main pipe and the refrigerant flowing through the third bypass pipe 41 (described later).

The first bypass pipe 21 has one end connected between the injection compressor 1 and the four-way valve 3 and the other end branched, and connected in parallel to the pipe connected to the

outdoor heat exchangers

9a and 9b. Is. The second bypass pipe 31 is connected to the third bypass pipe 41 at one end and the other pipe different from the pipes of the two

outdoor heat exchangers

9a and 9b with the other end connected to the first bypass pipe 21. Are connected in parallel. The third bypass pipe 41 has one end connected between the

outdoor heat exchangers

9a and 9b and the main pipe connected to the

indoor units

200a and 200b, and the other end connected to the injection port of the injection compressor 1. Is.

The first

flow control valves

5a and 5b control the flow rate of the refrigerant flowing between the

indoor units

200a and 200b. The second flow rate control valve 7 controls the flow rate of the refrigerant flowing between the refrigerant heat exchanger 6 and the two-

way valves

8a and 8b. The third flow

rate control valves

32 a and 32 b control the flow rate of the refrigerant that flows from the first flow path switching device B through the second bypass pipe 31. The fourth flow control valve 42 adjusts the flow rate of the refrigerant flowing through the third bypass pipe 41.

The first flow path switching device A is composed of two-

way valves

8a, 8b, 22a and 22b. The second flow path switching device B includes two-

way valves

10a and 10b and third

flow control valves

32a and 32b. The two-

way valves

8a, 8b, 10a, 10b, 22a, and 22b can be opened and closed regardless of the pressure at the inlet / outlet of the valve, and switch the refrigerant flow path.

The two-

way valves

8a, 8b, 10a, 10b, 22a, and 22b are configured as shown in FIG. 5 so that they can be opened and closed regardless of the pressure at the inlet / outlet of the valve, and the direction of the refrigerant that can be shut off. Shows an example of the structure and operation of a one-way two-way valve. The two-way valve includes a valve main body V connecting the main pipe M1 and the main pipe M2, a pressure adjusting device X for adjusting the pressure in the pressure chambers P1 and P2 in the valve main body V, and the valve main body V and the pressure adjusting device X. It consists of pipes T1, T2, T3, and T4 connected to the refrigerant pipe.

The valve main body V is connected to the moving walls W1, W2 that move to the left and right according to the pressures of the pressure chambers P1, P2, and is moved to the left and right on the valve seat U to open and close the valve. It consists of a slide valve S. The pressure adjusting device X includes a small slide valve S and a small slide valve driving device Y that drives the small slide valve S. The small slide valve S connects the pipe T1 and the pipe T3, connects the pipe T2 and the pipe T4 (when the valve is opened), connects the pipe T1 and the pipe T2, and connects the pipe T3 and the pipe T4. Is selectively switched to one of the cases where the valve is electrically connected (when the valve is closed).

The pipe T1 has one end connected to the pressure adjusting device X and the other end connected to the main pipe M1. The pipe T2 has one end connected to the pressure adjusting device X and the other end connected to the pressure chamber P1. The pipe T3 has one end connected to the pressure adjusting device X and the other end connected to the pressure chamber P2. The pipe T4 is connected to a location that is always at a low pressure in the air conditioner, such as a low-pressure pipe, a suction pipe of the injection compressor 1, an accumulator, or the like.

In the two-way valve having such a configuration, as shown in FIG. 5A, when the small slide valve S is moved to the left by the small slide valve driving device Y, the pipe T1 and the pipe T3 are electrically connected. The pipe T2 and the pipe T4 are conducted. As a result, the pressure in the pressure chamber P1 becomes smaller than the pressure in the pressure chamber P2, the small slide valve S moves to the left, and the valve opens.

Further, as shown in FIG. 5B, when the small slide valve S is moved rightward by the small slide valve driving device Y, the pipe T1 and the pipe T2 are conducted, and the pipe T3 and the pipe T4 are conducted. . Thereby, the pressure of the pressure chamber P1 becomes larger than the pressure of the pressure chamber P2, the small slide valve S moves to the right, and the valve is closed.

As shown in FIG. 1, in the first embodiment, the two-

way valves

10a and 10b are in the direction from the

outdoor heat exchangers

9a and 9b to the four-way valve 3 (upward in the drawing), and the two-

way valves

8a and 8b are outdoor. The refrigerant is cut off only in the direction of flowing out of the outdoor unit 100 from the

heat exchangers

9a and 9b through the main pipe (downward on the paper surface). In addition, the arrow beside the valve in the figure indicates the direction of the refrigerant that can be shut off.

Next, description will be made with reference to FIGS. 2 to 4 showing the refrigerant flow of this apparatus and FIG. 7 to FIG. 9 which are ph diagrams (diagram showing the relationship between the refrigerant pressure and enthalpy). 2 to 4, thick solid lines indicate the flow of the refrigerant during operation, and the numbers [i] (i = 1, 2,...) In parentheses are i in the diagrams of FIGS. The piping part corresponding to a point (each state of a refrigerant | coolant) is shown.

FIG. 2 illustrates a flow in the case where cooling is performed by cooling indoor air with an indoor heat exchanger and radiating heat to the outside air with an outdoor heat exchanger (hereinafter referred to as “cooling operation”).
FIG. 3 illustrates a flow in the case where heating is performed by heating indoor air with an indoor heat exchanger and absorbing heat from the outside air with an outdoor heat exchanger (hereinafter, referred to as “all heating operation”).
In FIG. 4, indoor air is heated by the indoor heat exchanger, and one of the parallel heat exchangers (outdoor heat exchanger 9 a in FIG. 1) constituting the outdoor heat exchanger evaporates the refrigerant and heats it from the outside air. When the frost is heated to melt the frost generated in the outdoor heat exchanger 9b in the other parallel heat exchanger (outdoor heat exchanger 9b in FIG. 1) (hereinafter referred to as simultaneous heating and defrost operation). The flow of will be described. During these heating operations, the indoor heat exchanger functions as a condenser, and the outdoor heat exchanger functions as an evaporator. The same applies to the embodiments described later.

<Cooling only operation>
FIG. 2 is a diagram showing the refrigerant flow during the cooling only operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. FIG. 7 is a diagram showing the relationship between the refrigerant pressure and enthalpy during the cooling only operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. Hereinafter, the flow of the cooling only operation will be described with reference to FIGS. 2 and 7.

During the cooling operation, the four-way valve 3 is switched to the state shown by the broken line in FIG. In the second flow path switching device B, the refrigerant that has exited the four-way valve 3 branches and flows into both the

outdoor heat exchangers

9a and 9b, and the refrigerant that has exited the

outdoor heat exchangers

9a and 9b is the main pipe. And are switched to be supplied to the refrigerant heat exchanger 6 and the

indoor units

200a and 200b.

First, the low-temperature and low-pressure gas refrigerant is compressed by the injection compressor 1. The change of the refrigerant in the injection compressor 1 is expressed by an inclined line (points [1]-[2]) in which the enthalpy slightly increases in consideration of the efficiency of the injection compressor 1.

Then, the refrigerant in the middle of compression and the refrigerant flowing in from the third bypass pipe 41 merge. The change of the refrigerant at the time of merging is performed in a state where the pressure is substantially constant, and is represented by a horizontal line (point [2]-[3], point [9]-[3]). It is further compressed and discharged as a high-temperature and high-pressure gas refrigerant.

The change of the refrigerant in the injection compressor 1 is represented by an inclined line (points [3]-[4]) in which the enthalpy slightly increases in consideration of the efficiency of the injection compressor 1.

The high-temperature and high-pressure gas refrigerant discharged from the injection compressor 1 passes through the four-way valve 3, passes through the second flow path switching device B after the refrigerant is branched, and each of the branched refrigerants exchanges outdoor heat. Flows into the

containers

9a and 9b, where they exchange heat with the outside air outside to condense and liquefy and dissipate heat to the outside. The change of the refrigerant in the

outdoor heat exchangers

9a and 9b is performed under a substantially constant pressure, but is slightly inclined in the ph diagram in consideration of the pressure loss of the

outdoor heat exchangers

9a and 9b. It is represented by a line (point [4] → point [5]) close to the horizontal line.

Then, each refrigerant in the liquid state passes through the first flow path switching device A, then merges, passes through the main pipe, and flows through the third bypass pipe 41 in the refrigerant heat exchanger 6. As a result of cooling, the temperature drops. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger 6, a line close to a slightly inclined horizontal line in the ph diagram. (Point [5] → Point [6]).

A part of the refrigerant exiting the refrigerant heat exchanger 6 flows into the third bypass pipe 41, and the rest flows into the

indoor units

200a and 200b. The refrigerant that has flowed into the

indoor units

200a and 200b branches, and flows into the first

flow control valves

5a and 5b, respectively, and is reduced in pressure to a low-pressure gas-liquid two-phase state. The change of the refrigerant in the first

flow control valves

5a and 5b is performed under a constant enthalpy and is represented by a vertical line (point [6] → point [7]) in the ph diagram. Is done.

And each refrigerant decompressed to a low pressure flows into the

indoor heat exchangers

4a and 4b, evaporates by exchanging heat with indoor air, and cools the room. The change of the refrigerant in the

indoor heat exchangers

4a and 4b is performed under a substantially constant pressure, but is slightly inclined in the ph diagram in consideration of the pressure loss of the

indoor heat exchangers

4a and 4b. It is represented by a line (point [7] → point [1]) close to the horizontal line.

The low-temperature and low-pressure gaseous refrigerants that have exited the

indoor heat exchangers

4a and 4b join together, exit the

indoor units

200a and 200b, flow into the outdoor unit 100 through the main pipe, pass through the four-way valve 3 again, It is sucked into the injection compressor 1. As described above, the cooling operation is performed by circulating the refrigerant in the main circuit.

On the other hand, the refrigerant flowing into the third bypass pipe 41 is decompressed by the fourth flow control valve 42 and changes to a low-temperature gas-liquid two-phase state. The change of the refrigerant in the fourth flow control valve 42 is performed under a constant enthalpy and is represented by a vertical line (point [6] → point [8]) in the ph diagram. .

The refrigerant that has flowed into the refrigerant heat exchanger 6 is heated and evaporated by the refrigerant flowing through the main pipe. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger 6, a line close to a slightly inclined horizontal line in the ph diagram. (Point [8] → Point [9]).

<Heating operation>
FIG. 3 is a diagram showing the refrigerant flow during the heating only operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. FIG. 8 is a diagram showing the relationship between the refrigerant pressure and enthalpy during the heating only operation of the air-conditioning apparatus according to Embodiment 1 of the present invention. Hereinafter, the flow of the heating only operation will be described with reference to FIGS. 3 and 8.

During the all-heating operation, the four-way valve 3 is switched to the state shown by the solid line in FIG. In the first flow path switching device A and the second flow path switching device B, the refrigerant flowing into the outdoor unit 100 from the

indoor units

200a and 200b branches and is sent to both the

outdoor heat exchangers

9a and 9b. The refrigerant merges, passes through the four-way valve 3, and is switched to be sucked into the injection compressor 1.

Then, the refrigerant in the middle of compression and the refrigerant flowing in from the third bypass pipe 41 merge. The change of the refrigerant at the time of merging is performed in a state where the pressure is almost constant, and is represented by a horizontal line (point [2]-[3], point [10]-[3]). It is further compressed and discharged as a high-temperature and high-pressure gas refrigerant.

The change of the refrigerant in the injection compressor 1 is represented by an inclined line (points [3]-[4]) in which the enthalpy slightly increases in consideration of the efficiency of the injection compressor 1. The high-temperature and high-pressure gas refrigerant discharged from the injection compressor 1 passes through the four-way valve 3 and branches, then flows through the main pipe into the

indoor units

200a and 200b, and exchanges heat with indoor air to condense and liquefy. Heat the room.

The change of the refrigerant in the

indoor heat exchangers

4a and 4b. It is represented by a line (point [4] → point [5]) close to the horizontal line.

And each refrigerant | coolant which became this liquid state is pressure-reduced by 1st

flow control valve

5a, 5b. The change of the refrigerant in the first

flow control valves

5a and 5b is performed under a constant enthalpy and is represented by a vertical line (point [5] → point [6]) in the ph diagram. Is done.

The decompressed refrigerant merges, partly flows into the third bypass pipe 41 through the main pipe, and the rest flows into the refrigerant heat exchanger 6. The refrigerant that has flowed into the refrigerant heat exchanger 6 is cooled by the refrigerant flowing through the third bypass pipe 41 and the temperature is lowered. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger 6, a line close to a slightly inclined horizontal line in the ph diagram. (Point [6] → Point [7]).

The refrigerant that has exited the refrigerant heat exchanger 6 flows into the second flow control valve 7 and is depressurized to a low-pressure gas-liquid two-phase state. The change of the refrigerant in the second flow control valve 7 is performed under a constant enthalpy and is represented by a vertical line (point [7] → point [8]) in the ph diagram. .

Each refrigerant decompressed to a low pressure branches and then flows into the

outdoor heat exchangers

9a and 9b, exchanges heat with outdoor outdoor air, evaporates, and dissipates heat to the outdoor. The change of the refrigerant in the

outdoor heat exchangers

9a and 9b. It is represented by a line (point [8] → point [1]) close to the horizontal line. The low-temperature and low-pressure gaseous refrigerants that have exited the

outdoor heat exchangers

9a and 9b join together and are again sucked into the injection compressor 1 through the four-way valve 3. As described above, the heating operation is performed by circulating the refrigerant in the main circuit.

On the other hand, the refrigerant flowing into the third bypass pipe 41 is decompressed by the fourth flow control valve 42 and changes to a low-temperature gas-liquid two-phase state. The change of the refrigerant in the fourth flow control valve 42 is performed under a constant enthalpy and is represented by a vertical line (point [5] → point [9]) in the ph diagram. .

The refrigerant that has flowed into the refrigerant heat exchanger 6 is heated and evaporated by the refrigerant flowing through the main pipe. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger 6, a line close to a slightly inclined horizontal line in the ph diagram. (Point [9] → Point [10]). In this operation, when the outdoor air temperature is low, frost is generated in the

outdoor heat exchangers

9a and 9b, and when the operation is continued, the frost further increases and the heat exchange amount decreases.

<Simultaneous operation of heating defrost>
Next, the flow of the heating and defrost simultaneous operation (in the case of the heating operation in which the outdoor heat exchanger 9b is a defrost target) will be described with reference to FIGS. During the simultaneous heating and defrosting operation, the four-way valve 3 is switched to the same state as in the heating only operation as shown by the solid line in FIG.

In the first flow path switching device A, the refrigerant flowing from the

indoor units

200a and 200b into the outdoor unit 100 is sent only to the outdoor heat exchanger 9a, passes through the four-way valve 3, and is sucked into the injection compressor 1. To be switched.
Part of the refrigerant discharged from the injection compressor 1 passes through the first bypass pipe 21, passes through the first flow path switching device A, flows into the outdoor heat exchanger 9b, and enters the second bypass pipe. It is switched so as to pass through 31 and merge with the refrigerant in the third bypass pipe 41.

Next, the refrigerant that is being compressed and the refrigerant that flows in from the third bypass pipe 41 merge. The change of the refrigerant at the time of merging is performed in a state where the pressure is substantially constant, and is represented by a horizontal line (point [2]-[3], point [11]-[3]).

The refrigerant is further compressed and discharged as a high-temperature and high-pressure gas refrigerant. The change of the refrigerant in the injection compressor 1 is represented by an inclined line (points [3] to [4]) in which the enthalpy slightly increases in consideration of the efficiency of the injection compressor 1.

A part of the high-temperature and high-pressure gas refrigerant discharged from the injection compressor 1 flows into the first bypass pipe 21, the rest passes through the four-way valve 3, flows into the

indoor units

200a and 200b through the main pipe, Heat is exchanged with room air to condense and heat the room. The change of the refrigerant in the

indoor heat exchangers

And each refrigerant | coolant which became this liquid state passes the 1st

flow control valve

5a, 5b, and is pressure-reduced. The change of the refrigerant in the first

flow control valves

5a and 5b is performed under a constant enthalpy and is represented by a vertical line (point [5] → point [6]) in the ph diagram. Is done. The decompressed refrigerant merges, partly flows into the third bypass pipe 41 through the main pipe, and the rest flows into the refrigerant heat exchanger 6.

The refrigerant that has flowed into the refrigerant heat exchanger 6 is cooled by the refrigerant flowing through the third bypass pipe 41, and the temperature decreases. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger 6, a line close to a slightly inclined horizontal line in the ph diagram. (Point [6] → Point [7]).

The refrigerant that has exited the refrigerant heat exchanger 6 flows into the second flow control valve 7 and is decompressed to a low-pressure gas-liquid two-phase state. The change of the refrigerant in the second flow control valve 7 is performed under a constant enthalpy and is represented by a vertical line (point [7] → point [8]) in the ph diagram. .

And each refrigerant decompressed to a low pressure passes through the first flow path switching device A, flows into the outdoor heat exchanger 9a, evaporates by exchanging heat with outdoor outdoor air, and dissipates heat to the outdoor. The change of the refrigerant in the outdoor heat exchanger 9a is performed under a substantially constant pressure, but in consideration of the pressure loss of the outdoor heat exchanger 9a, a line close to a slightly inclined horizontal line in the ph diagram. (Point [8] → Point [1]). The low-temperature and low-pressure gas refrigerant exiting the outdoor heat exchanger 9a passes through the four-way valve 3 again and is sucked into the injection compressor 1. As described above, the heating operation is performed by circulating the refrigerant in the main circuit.

On the other hand, the refrigerant flowing into the third bypass pipe 41 is decompressed by the fourth flow control valve 42 and changes to a low-temperature gas-liquid two-phase state. The change of the refrigerant in the fourth flow control valve 42 is performed under a constant enthalpy and is represented by a vertical line (point [6] → point [9]) in the ph diagram. .

Then, the refrigerant that has passed through the fourth flow control valve 42 merges with the refrigerant that has flowed from the second bypass pipe 31. The change in the refrigerant at the time of merging is performed in a state where the pressure is almost constant, and is represented by a horizontal line (point [9] −point [10], point [13] −point [10]) in the ph diagram. The

The merged refrigerant flows into the refrigerant heat exchanger 6 and is heated and evaporated by the refrigerant flowing through the main pipe. The change of the refrigerant in the refrigerant heat exchanger 6 is performed under a substantially constant pressure, but in consideration of the pressure loss of the refrigerant heat exchanger, a line close to a slightly inclined horizontal line in the ph diagram ( Point [10] → point [11]).

Further, the refrigerant flowing into the first bypass pipe 21 passes through the first flow path switching device A and condenses while melting the frost generated in the outdoor heat exchanger 9b. The change of the refrigerant in the outdoor heat exchanger 9b is performed under a substantially constant pressure. However, in consideration of the pressure loss of the outdoor heat exchanger 9b, a line close to a slightly inclined horizontal line in the ph diagram. (Point [4] → Point [12]).

The condensed refrigerant is decompressed by the third flow control valve 32b, and changes to a refrigerant in a gas-liquid two-phase state. The change of the refrigerant in the third flow control valve 32b is performed under a constant enthalpy and is represented by a vertical line (point [12] → point [13]) in the ph diagram. .
The decompressed refrigerant passes through the second bypass pipe 31 and merges with the refrigerant flowing through the third bypass pipe 41.

As described above, in this operation mode, the frost in the outdoor heat exchanger 9b can be melted while heating the room. Further, in the case of heating operation in which the outdoor heat exchanger 9a is a defrost target, the first flow path switching device A and the second flow path switching device B are switched to melt the frost in the outdoor heat exchanger 9a. Then, the outdoor heat exchanger 9b performs an operation of radiating heat to the outside.

<Method of adjusting the discharge temperature of the injection compressor 1>
Next, a method for adjusting the discharge temperature of the injection compressor 1 will be described. When the discharge temperature of the injection compressor 1 measured by the temperature sensor 2 is equal to or higher than the upper limit temperature for ensuring the reliability of the injection compressor 1, the opening degree of the fourth flow control valve 42 is increased. When the temperature falls below the upper limit temperature, the opening degree of the fourth flow control valve 42 is reduced.
During heating operation at a low outside air temperature, the discharge temperature of the injection compressor 1 rises, and thus the discharge temperature of the injection compressor 1 is abnormally increased by checking the discharge temperature of the injection compressor 1 in this way. Is preventing.

As described above, in the air conditioner 1000 of the first embodiment, there are three operation modes of the cooling only operation, the heating only operation, and the heating defrost simultaneous operation, frost is generated in the outdoor heat exchanger 9b, and the air volume is reduced. When the performance starts to decrease due to a decrease or a decrease in the evaporation temperature, the heating and defrosting operation can be performed simultaneously to continuously heat the room.

In the air conditioner 1000 of the first embodiment, the refrigerant for performing the defrost is injected not in the suction side of the injection compressor 1 but in the middle of the compression process in the injection compressor 1. There is no need to reduce the pressure of the refrigerant to perform suction. Therefore, in the injection compressor 1, only the refrigerant circulating in the main circuit for heating needs to be increased from low pressure to high pressure, and the injected intermediate-pressure gas-liquid two-phase state refrigerant is increased from the intermediate pressure. What is necessary is just to raise to a high pressure. Therefore, the work of the injection compressor 1 is reduced, and the efficiency of the heat pump (heating capacity / work of the injection compressor 1) is improved. As a result, it can also contribute to an energy saving effect.

Further, in the air conditioner 1000 of the first embodiment, the gas-liquid two-phase refrigerant flowing into the injection compressor 1 from the injection port is heated by the intermediate-pressure gas refrigerant in the middle of compression, and the injection compression Since it changes to a gas state inside the machine 1, the reliability of the heat pump is improved. In the first embodiment, the difference in enthalpy of the refrigerant used for defrosting (the length of the line segment from point [4] to point [12] in FIG. 9) is calculated using the conventional air conditioner (in FIG. 8). The length of the line segment from point [6] to point [7] can be made larger, and defrosting can be performed with a small amount of refrigerant flow, thereby improving the heating capacity.

Further, in the air conditioner 1000 of the first embodiment, the temperature sensor 2 for measuring the refrigerant discharge temperature of the injection compressor 1 is provided, and the fourth flow control valve 42 is controlled according to the discharge temperature. Therefore, an increase in discharge temperature under low outside air conditions can be suppressed, and the reliability of the injection compressor 1 is improved.

Further, in the air conditioner 1000 of the first embodiment, in the heating operation, the outdoor heat exchanger 9b to be defrosted exchanges heat by flowing a refrigerant in a direction parallel to the flow direction of the outside air, and the outdoor heat not to be defrosted. The exchanger 9a exchanges heat by flowing a refrigerant in a direction opposite to the flow direction of the outside air. Hereinafter, the flow of the refrigerant in the heating and defrost simultaneous operation will be described with reference to FIG.

The

outdoor heat exchangers

9a and 9b shown in FIG. 6 are fin-tube heat exchangers in which a plurality of heat transfer tubes penetrates in a direction perpendicular to the plurality of fins, and are divided into two rows in the air flow direction and vertically divided into two. Shows the configuration. In the outdoor heat exchanger 9a, a low-temperature and low-pressure refrigerant in a gas-liquid two-phase state flows from the downstream row with respect to the air flow, evaporates while releasing heat to the air, moves to the upstream row, and further evaporates. And flows out of the outdoor heat exchanger 9a. On the other hand, in the outdoor heat exchanger 9b performing defrosting, high-temperature and high-pressure refrigerant flows from the upstream row of the air flow, condenses while heating and melting the frost, and moves to the downstream row. Furthermore, it condenses and flows out from the outdoor heat exchanger 9b. In the outdoor heat exchanger 9a that is not subject to defrosting, the temperature difference between the air and the refrigerant can be increased, and an efficient operation can be performed. In the outdoor heat exchanger 9b that is subject to defrosting, A refrigerant having a higher temperature can be supplied, and frost can be efficiently melted.

Further, the air conditioner 1000 according to the first embodiment uses a two-way valve that can perform an opening / closing operation regardless of the magnitude of the pressure at the inlet / outlet of the valve, and that restricts the flow of the refrigerant to one direction. Therefore, it is possible to use a two-way valve with a simple internal structure that can block only the flow of refrigerant in one direction.

Further, in the air conditioner 1000 of the first embodiment, a plurality of outdoor heats are arranged so that the direction of the refrigerant flowing out from the

outdoor heat exchangers

9a and 9b to the main pipe matches the direction that can be blocked by the two-way valve. A first flow path switching device A and a second flow path switching device B are installed in each of the

exchangers

9a and 9b, and the first flow path switching device A and the second flow path are all in all operation modes. The refrigerant in the switching device B can be shut off without leakage.

Further, in the air conditioner 1000 of the first embodiment, the configuration in which the third

flow control valves

32a and 32b are provided in the second bypass pipe 31 has been described, but the second bypass pipe 31 is branched. Two two-way valves may be provided for each of the two pipes, and one flow rate control valve may be provided for one pipe after joining. According to this configuration, the temperature of the refrigerant flowing into the outdoor heat exchanger 9b to be defrosted decreases, the temperature change of the refrigerant in the outdoor heat exchanger 9b to be defrosted can be reduced, and the defrosting unevenness can be reduced. Increases frost efficiency.

In the air conditioner 1000 of the first embodiment, one end is connected between the

outdoor heat exchangers

9a and 9b and the second flow rate control valve 7, and the other end is connected to the injection port of the injection compressor 1. The refrigerant heat exchanger 6 that exchanges heat between the refrigerant that flows between the third bypass pipe 41 to be connected, the

outdoor heat exchangers

9a and 9b, and the second flow rate control valve 7, and the refrigerant that flows through the third bypass pipe 41. A fourth flow rate control valve 42 for controlling the flow rate of the refrigerant flowing through the third bypass pipe 41 is provided. In addition, the other end of the second bypass pipe 31 is connected to a stage preceding the refrigerant heat exchanger 6 of the third bypass pipe 41. Therefore, in the refrigerant heat exchanger 6, heat can be exchanged between the refrigerant flowing out of the outdoor heat exchanger 9b to be defrosted and the refrigerant flowing through the main pipe, and the efficiency is improved.

In addition, in the air conditioning apparatus 1000 of this Embodiment 1, although the order which performs the defrost at the time of heating defrost simultaneous operation is not demonstrated, in the case of the heat exchanger shown in FIG. 6, in the upper outdoor heat exchanger 9a. After performing the defrosting operation, the outdoor heat exchanger 9b may perform the defrosting operation. According to this configuration, the water after defrosting is re-iced by the lower outdoor heat exchanger (outdoor heat exchanger 9b in FIG. 6) in the upper outdoor heat exchanger (outdoor heat exchanger 9a in FIG. 6). However, the defrosting operation can be performed without leaving frost, and the reliability of the air conditioner is improved.

Embodiment 2. FIG.
The second embodiment of the present invention will be described below with reference to FIGS. In addition, the same code | symbol is attached | subjected to the same location. FIG. 10 is a diagram illustrating a refrigerant circuit of the air-conditioning apparatus according to Embodiment 2 of the present invention. FIG. 11 is a diagram illustrating the refrigerant flow during the simultaneous heating and defrosting operation of the air-conditioning apparatus according to Embodiment 2 of the present invention. FIG. 12 is a diagram showing the relationship between the refrigerant pressure and enthalpy during the simultaneous heating and defrosting operation of the heat pump according to the second embodiment of the present invention. Hereinafter, the air conditioner 1000 will be described with reference to FIG.

The air conditioner 1000 includes an outdoor unit 100,

indoor units

The outdoor unit 100 includes two-

way valves

51 a and 51 b connected to the second bypass pipe 31, a fifth flow control valve 50 (the first bypass flow control valve in the present invention) in the first bypass pipe 21. Equivalent). A second pressure sensor 56 is provided on the discharge side of the injection compressor 1. Further, a first pressure sensor 55 is provided between the refrigerant heat exchanger 6 and the first

flow control valves

5a and 5b (on the first

flow control valves

5a and 5b side from the branch point to the third bypass pipe 41). Is provided.

The two-

way valves

22a, 22b, 51a, 51b are configured by the same valves as in the first embodiment shown in FIG. 5 or electromagnetic valves that open and close the valves by a motor.

In the second embodiment, similarly to the first embodiment, the two-

way valves

8a, 8b, 10a, 10b, 22a, 22b, 51a, 51b block the refrigerant only in the direction of the arrow in the figure.

The check valve 52 is provided between a portion where the two-

way valves

51a and 51b are provided and a portion where the second bypass pipe 31 and the third bypass pipe 41 are connected. The check valve 52 is for preventing the refrigerant from flowing from the portion where the second bypass pipe 31 and the third bypass pipe 41 are connected toward the two-

way valves

51a and 51b. The second pressure sensor 56 measures the discharge pressure of the refrigerant of the injection compressor 1. The first pressure sensor 55 is located between the first

flow control valves

5a and 5b and the refrigerant heat exchanger 6 (on the first

flow control valves

5a and 5b side from the branch point to the third bypass pipe 41). The pressure is measured.

Other configurations are the same as those in the first embodiment, and a description thereof is omitted.

Next, description will be made with reference to FIG. 11 showing the refrigerant flow of this apparatus and FIG. 12 which is a ph diagram (diagram showing the relationship between the refrigerant pressure and enthalpy). In FIG. 11, the thick solid line indicates the flow of the refrigerant during operation, and the numbers [i] (i = 1, 2,...) In parentheses are i points (each state of the refrigerant in the diagram of FIG. 12). The piping part corresponding to) is shown.

In FIG. 11, indoor air is heated by the

indoor heat exchangers

4a and 4b, and one of the parallel heat exchangers constituting the outdoor heat exchanger (the outdoor heat exchanger 9a in FIG. 11) evaporates the refrigerant. When heat is absorbed from outside air and the other parallel heat exchanger (outdoor heat exchanger 9b in FIG. 11) heats the frost to melt the frost generated in the outdoor heat exchanger 9b (hereinafter, simultaneous heating and defrost operation) Will be described. During the heating operation, the

indoor heat exchangers

4a and 4b function as condensers, and the

outdoor heat exchangers

9a and 9b function as evaporators. The same applies to the embodiments described later.

Other operation modes, cooling operation, and heating operation are the same as in the first embodiment and will not be described.

In the first flow path switching device A, the refrigerant flowing from the

indoor units

indoor heat exchangers

And each refrigerant | coolant which became this liquid state passes the 1st

flow control valve

5a, 5b, and is pressure-reduced. The change of the refrigerant in the first

flow control valves

Further, the refrigerant flowing into the first bypass pipe 21 is decompressed by the fifth flow control valve 50. The change of the refrigerant in the fifth flow control valve 50 is performed under a constant enthalpy and is represented by a vertical line (point [4] → point [12]) in the ph diagram. . The decompressed refrigerant passes through the first flow path switching device A and condenses while melting the frost generated in the outdoor heat exchanger 9b. The change of the refrigerant in the outdoor heat exchanger 9b is performed under a substantially constant pressure. However, in consideration of the pressure loss of the outdoor heat exchanger 9b, a line close to a slightly inclined horizontal line in the ph diagram. (Point [12] → Point [13]).

The condensed refrigerant passes through the second bypass pipe 31 and merges with the refrigerant flowing through the third bypass pipe 41.

The method for adjusting the discharge temperature of the injection compressor 1 is the same as in the first embodiment, and a description thereof will be omitted.

As described above, the air-conditioning apparatus 1000 according to the second embodiment can reduce the temperature and temperature change of the refrigerant flowing into the outdoor heat exchanger 9b to be defrosted together with the same effects as those of the first embodiment. Unevenness can be reduced and defrosting efficiency is improved.

Furthermore, in the air conditioning apparatus 1000 of the second embodiment, the second pressure sensor 56 that measures the refrigerant discharge pressure of the injection compressor 1 is provided, and becomes a predetermined discharge pressure during the simultaneous heating and defrosting operation. Since the fifth flow control valve 50 is controlled as described above, the heating capacity of the

indoor heat exchangers

4a and 4b can be maintained. Specifically, when the discharge pressure is lower than the predetermined pressure, the opening degree of the fifth flow control valve 50 is reduced, and when the discharge pressure is higher than the predetermined pressure, the fifth flow control valve Increase the opening of 50.

Furthermore, in the air conditioner 1000 of the second embodiment, the first flow control is performed between the first

flow control valves

5a and 5b and the refrigerant heat exchanger 6 (the first flow control is performed rather than the branch point to the third bypass pipe 41). Since the first pressure sensor 55 for measuring the pressure of the

valves

5a and 5b) is provided and the second flow control valve 7 is controlled according to the pressure, the fourth flow control valve 42 and the refrigerant heat The pressure of the refrigerant flowing into the exchanger 6 can be controlled to a predetermined value, the amount of heat exchange in the refrigerant heat exchanger 6 and the

outdoor heat exchangers

9a and 9b can be controlled, and the operation is stabilized. Specifically, when the pressure drops below a predetermined pressure, the opening of the second flow control valve 7 is increased, and when the pressure rises above the predetermined pressure, the second flow control valve 7 Reduce the opening.

1 injection compressor, 2 temperature sensor, 3 way valve, 4a, 4b indoor heat exchanger, 5a, 5b first flow control valve, 6 refrigerant heat exchanger, 7 second flow control valve, 8a, 8b One way valve, 9a, 9b outdoor heat exchanger, 10a, 10b two way valve, 21 first bypass pipe, 22a, 22b two way valve, 31 second bypass pipe, 32a, 32b third flow control valve, 41 3rd bypass piping, 42 4th flow control valve, 50 5th flow control valve, 51a, 51b two-way valve, 52 check valve, 55 1st pressure sensor, 56 2nd pressure sensor, 100 outdoor Unit, 200a, 200b, indoor unit, 1000, air conditioner, A, first flow switching device, B, second flow switching device, M1, M2 main piping, P1, P2 pressure chamber, S Small slide valve, T1, T2, T3, T4 pipe, U valve seat, V valve body, W1, W2 moving walls, X pressure regulator, Y miniature slide valve actuating device.

Claims

In an air conditioner including a main pipe that connects a refrigerant to circulate between an indoor unit and an outdoor unit,
An indoor heat exchanger,
A flow control valve for controlling the flow rate of the refrigerant flowing through the indoor heat exchanger;
An injection compressor equipped with an injection port capable of injecting refrigerant into the refrigerant in the middle of compression;
A refrigerant flow switching device for switching between cooling operation and heating operation;
A plurality of outdoor heat exchangers connected in parallel;
A first bypass pipe having one end connected between the injection compressor and the refrigerant flow switching device, and the other end connected to one of the inlet / outlet sides of the plurality of outdoor heat exchangers;
A second bypass pipe having one end connected to the injection port or a pipe connected to the injection port, and the other end connected to the other of the plurality of outdoor heat exchangers on the inlet / outlet side;
A first flow path switching device that switches a flow path of the refrigerant to either the main pipe or the first bypass pipe;
A second flow path switching device that switches the flow path of the refrigerant to either the main pipe or the second bypass pipe;
At the time of defrost operation to remove frost formation of the outdoor heat exchanger of any of the plurality of outdoor heat exchangers,
The first flow path switching device allows a part of the refrigerant discharged from the injection compressor to pass through the first bypass pipe, and out of the plurality of outdoor heat exchangers, outdoor heat exchange to be defrosted Supply to the vessel,
An air conditioner that causes a part of the refrigerant supplied to the outdoor heat exchanger to be defrosted to flow into the second bypass pipe by the second flow path switching device.
In heating operation,
Among the plurality of outdoor heat exchangers, the defrost target outdoor heat exchanger exchanges heat by flowing a refrigerant in a direction parallel to the flow direction of the outside air,
The air conditioner according to claim 1, wherein among the plurality of outdoor heat exchangers, an outdoor heat exchanger that is not a defrost target performs heat exchange by flowing a refrigerant in a direction opposite to a flow direction of the outside air.
The first flow path switching device and the second flow path switching device are:
The air conditioning apparatus according to claim 1 or 2, comprising a two-way valve that can be opened and closed regardless of the pressure at the inlet / outlet of the valve.
The first flow path switching device and the second flow path switching device are:
The air conditioning apparatus according to claim 3, wherein a direction in which the flow of the refrigerant is blocked is limited to one direction.
The first flow path switching device and the second flow path switching device are:
The air conditioner according to claim 4, wherein a flow of refrigerant in a direction of flowing out from the outdoor heat exchanger to the main pipe is blocked.
The air conditioner according to any one of claims 1 to 5, wherein the second bypass pipe includes a second bypass flow rate control valve that controls a flow rate of the refrigerant.
A third bypass pipe connecting one end between the outdoor heat exchanger and the flow control valve and connecting the other end to the injection port;
A refrigerant flowing between the outdoor heat exchanger and the flow rate control valve, a refrigerant heat exchanger performing heat exchange of the refrigerant flowing through the third bypass pipe,
An injection flow rate control valve for controlling the flow rate of the refrigerant flowing through the third bypass pipe,
The air conditioner according to any one of claims 1 to 6, wherein the other end of the second bypass pipe is connected to the third bypass pipe.
The air conditioning apparatus according to claim 7, wherein the other end of the second bypass pipe is connected to the third bypass pipe at a stage preceding the refrigerant heat exchanger.
A temperature sensor for measuring the temperature of the refrigerant discharged from the injection compressor,
If the value of the temperature sensor is equal to or higher than a predetermined temperature, increase the opening of the injection flow control valve,
The air conditioner according to claim 7 or 8, wherein when the value of the temperature sensor is lower than a predetermined temperature, the opening of the injection flow control valve is reduced.
An outdoor flow rate control valve provided between the refrigerant heat exchanger and the first flow path switching device for controlling the flow rate of the refrigerant;
A first pressure sensor that detects a pressure between the flow control valve and the refrigerant heat exchanger and on the flow control valve side from a branch point to the third bypass pipe;
The air conditioner according to any one of claims 7 to 9, wherein an opening degree of the outdoor flow rate control valve is controlled based on a value detected by the first pressure sensor.
A second pressure sensor for detecting the pressure of the refrigerant discharged from the injection compressor;
A first bypass flow rate control valve provided in the first bypass pipe for controlling the flow rate of the refrigerant;
The air conditioner according to any one of claims 1 to 10, wherein an opening degree of the first bypass flow rate control valve is controlled based on a value detected by the second pressure sensor.
In the plurality of outdoor heat exchangers divided vertically,
The defrost operation is performed in the outdoor heat exchanger located below the outdoor heat exchanger after the defrost operation is performed in the outdoor heat exchanger located in the divided outdoor heat exchanger. The air conditioning apparatus according to any one of to 11.
The indoor heat exchanger and the flow control valve are accommodated in the indoor unit,
The injection compressor, the refrigerant flow switching device, the plurality of outdoor heat exchangers, the first bypass piping, the second bypass piping, and the first flow switching device; The second flow path switching device is housed in the outdoor unit,
The air conditioner according to any one of claims 1 to 12, wherein at least one indoor unit is connected to the outdoor unit.