JP2022051014A - Air conditioner - Google Patents

Abstract

To provide a highly reliable air conditioner preventing a compressor from being damaged.SOLUTION: An air conditioner is provided with a passage returning refrigerant to a compressor from an outdoor heat exchanger 5 via an auxiliary heat exchanger 18 separately from a passage directly returning the refrigerant to the compressor from the outdoor heat exchanger 5, and a switching device 14 switching between the passage directly returning the refrigerant to the compressor and the passage returning the refrigerant to the compressor via the auxiliary heat exchanger, between a four-way valve 4 and a compressor 3 in a refrigeration cycle. The air conditioner controls the switching device when switching the operation to a normal heating operation from a defrosting/heating operation to gradually switch the passage on an auxiliary heat source side to the passage directly returning the refrigerant. Accordingly, the refrigerant is gradually switched to the passage directly returning it to the compressor from the passage on the auxiliary heat source side having long piping and thereby returning of liquid refrigerant to the compressor at a time is suppressed and damage on the compressor due to liquid compression is prevented, to make the air conditioner have high reliability.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an air conditioner capable of continuing heating operation even during defrosting.

Patent Document 1 discloses an air conditioner capable of continuing heating operation even during defrosting. This air conditioner has a configuration in which a heat storage tank is provided in a compressor provided in the outdoor unit, heat generated by the compressor is stored in the heat storage layer, and the accumulated heat is used for defrosting during heating operation. Therefore, the heating operation can be continued even during defrosting, and comfortable defrosting / heating operation can be realized.

Japanese Unexamined Patent Publication No. 2000-104586

The present disclosure provides a highly reliable air conditioner that reduces the return of liquid refrigerant to the compressor that occurs when returning from defrosting / heating operation to normal heating operation and prevents damage to the compressor due to liquid compression. offer.

The air conditioner in the present disclosure includes a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, a refrigerating cycle connected to the four-way valve, and a control unit for controlling the operation of the refrigerating cycle. An air conditioner, wherein the refrigeration cycle further comprises an auxiliary heat exchanger for heating the refrigerant, and from the outdoor heat exchanger between the four-way valve of the refrigeration cycle and the suction side of the compressor. Apart from the path for returning the refrigerant directly to the compressor, the path for returning the refrigerant from the outdoor heat exchanger to the suction side of the compressor via the auxiliary heat exchanger, and the path for returning the refrigerant directly to the compressor. A switching device for switching the path for returning the refrigerant to the suction side of the compressor via the auxiliary heat exchanger is provided, and the control unit is used for defrosting / heating operation to melt the frost adhering to the outdoor heat exchanger. Occasionally, the refrigerant is returned to the suction side of the compressor via the auxiliary heat exchanger, and when switching back from the defrosting / heating operation to the normal heating operation, the switching device is controlled to control the outdoor heat exchanger. The refrigerant is gradually switched from the path on the auxiliary heat exchanger side to the path directly returned to the compressor.

The air conditioner in the present disclosure is provided with a switching device for switching the refrigerant path between the four-way valve and the suction side of the compressor, so that the pipe length from the switching device to the compressor during heating operation is shortened. Even if it is, when switching from the defrosting / heating operation to the normal heating operation, the refrigerant has a long pipe length. Since it is gradually switched to, it is possible to suppress the return of the liquid refrigerant to the compressor at once. Therefore, it is possible to prevent damage to the compressor due to liquid compression and provide a highly reliable air conditioner.

Schematic configuration diagram showing the flow of the refrigerant during the normal heating operation of the air conditioner according to the first embodiment. Schematic configuration diagram showing the flow of refrigerant during defrosting / heating operation of the air conditioner according to the first embodiment. Schematic configuration diagram showing the flow of refrigerant during operation of the minimum cooling capacity of the air conditioner according to the first embodiment. An explanatory diagram illustrating the AB passage opening of the switching device for switching the refrigerant flow when switching from the normal heating operation of the air conditioner to the defrosting / heating operation in the first embodiment. An explanatory diagram illustrating the AC passage opening of the switching device for switching the refrigerant flow when switching from the normal heating operation of the air conditioner to the defrosting / heating operation in the first embodiment. A perspective view showing a switching device for an air conditioner according to the first embodiment. XX sectional view of FIG. 5A showing the switching device of the air conditioner according to the first embodiment.

(Knowledge, etc. that became the basis of this disclosure)
At the time when the inventors came up with the present disclosure, the air conditioner was, as shown in Patent Document 1, an air conditioner capable of continuing the heating operation by using the heat storage tank even at the time of defrosting. As was known, this air conditioner did not have the heat storage tank available during the cooling operation. Therefore, the cooling operation is performed in the same manner as an air conditioner without a heat storage layer. For example, the cooling capacity at a low load where the room temperature is stable and the cooling load is small is the capacity of the compressor, that is, the compressor. It is the minimum cooling capacity determined according to the minimum number of rotations that can be output.

Therefore, the present inventors can effectively utilize the heat storage layer to continue the cooling operation with a cooling capacity lower than the minimum cooling capacity operation determined by the minimum rotation speed of the compressor during the cooling operation. I considered making it.

As a result, it has become possible to switch the minimum cooling capacity during the cooling operation to a lower cooling capacity and continue the cooling operation. However, with such a configuration, as will be described in detail later, when returning from the defrosting / heating operation to the normal heating operation, a large amount of liquid refrigerant returns to the compressor, causing damage to the compressor due to liquid compression. I discovered that the problem of becoming easier arises.

The present inventors have discovered such a problem and have come to construct the subject matter of the present disclosure in order to solve the problem.

Therefore, the present disclosure provides a highly reliable air conditioner that prevents damage due to liquid compression of the compressor that occurs when returning from the defrosting / heating operation to the normal heating operation.

Hereinafter, embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations for substantially the same configuration may be omitted. This is to prevent the following explanation from becoming unnecessarily redundant and to facilitate the understanding of those skilled in the art.

It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 5A and 5B.

[1-1. Constitution]
In FIGS. 1 to 3, the air conditioner of the present embodiment is configured by connecting the outdoor unit 1 and the indoor unit 2 to each other by a refrigerant pipe.

A compressor 3, a four-way valve 4, an outdoor heat exchanger 5, and an expansion valve 6 are provided inside the outdoor unit 1, and an indoor heat exchanger 7 is provided inside the indoor unit 2. The outdoor unit 1 and the indoor unit 2 are connected to each other via a refrigerant pipe to form a refrigeration cycle.

More specifically, the compressor 3 of the outdoor unit 1 is connected to the outdoor heat exchanger 5 via the refrigerant pipe 8, the four-way valve 4, and the refrigerant pipe 9, and the outdoor heat exchanger 5 is connected to the refrigerant pipe 10, the expansion valve 6, and so on. It is connected to the indoor heat exchanger 7 via the refrigerant pipe 11.

Further, the indoor heat exchanger 7 of the indoor unit 2 is connected to the four-way valve 4 via the refrigerant pipe 12, and is a switching device such as a refrigerant pipe 13, a three-way valve as shown in FIGS. 5A and 5B (hereinafter referred to as a three-way valve). (Referred to as) 14, the refrigerant pipe 15, and the compressor 3 are connected to the refrigerant suction side.

Further, a heat storage tank 17 is provided around the compressor 3, and an auxiliary heat exchanger (hereinafter referred to as a heat storage heat exchanger) 18 such as a heat storage heat exchanger is provided inside the heat storage tank 17. A heat storage material (for example, an ethylene glycol aqueous solution) 19 for heat exchange with the heat storage heat exchanger 18 is filled, and the heat storage tank 17, the heat storage heat exchanger 18, and the heat storage material 19 constitute a heat storage device.

Further, the three-way valve 14 and the heat storage heat exchanger 18 of the heat storage device are connected via a refrigerant pipe 21 including a capillary tube 20, and the heat storage heat exchanger 18 is connected to the three-way valve 14 via a refrigerant pipe 22. It is connected to the refrigerant pipe 15 connecting to the refrigerant suction side of 3.

Further, inside the indoor unit 2, in addition to the indoor heat exchanger 7, an indoor fan 7a, upper and lower blades (not shown), and left and right blades (not shown) are provided. The indoor heat exchanger 7 exchanges heat between the indoor air sucked into the indoor unit 2 by the indoor fan 7a and the refrigerant flowing inside the indoor heat exchanger 7, and the air warmed by the heat exchange during heating. Is blown into the room, while air cooled by heat exchange is blown into the room during cooling. The upper and lower blades change the direction of the air blown from the indoor unit 2 up and down as necessary, and the left and right blades change the direction of the air blown from the indoor unit 2 to the left and right as necessary.

Further, the outdoor unit 1 is provided with the outdoor air temperature detecting means 23 and the piping temperature detecting means 24 together with the outdoor fan 5a, and the indoor unit 2 is provided with the indoor temperature detecting means 25.

The compressor 3, indoor fan 7a, upper and lower blades, left and right blades, four-way valve 4, expansion valve 6, three-way valve 14, outdoor fan 5a, outside air temperature detecting means 23, piping temperature detecting means 24, and indoor temperature detecting means 25. , Etc. are electrically connected to the control unit 26 (for example, a microcomputer), and the compressor 3, the outdoor fan 5a, the indoor fan 7a, the upper and lower blades, the left and right blades, the four-way valve 4, the expansion valve 6, and the three-way valve 14 are operated or operated. The operation is controlled based on the control signal from the control unit 26.

Here, the control unit 26 has a temperature difference between the indoor temperature detected by the indoor temperature detecting means 25 and the set temperature within a predetermined range when the cooling operation is set to the minimum cooling capacity operation during the cooling operation. Occasionally, the inlet A connected to the four-way valve 4 of the three-way valve 14 is controlled to communicate with the second outlet C in addition to the first outlet B. As a result, the refrigerant returns to the compressor 3 via the refrigerant pipe 15 connected to the first outlet B, and the remaining refrigerant portion passes through the heat storage heat exchanger 18 of the heat storage device connected to the second outlet C to the compressor 3. The heat exchange by the heat storage heat exchanger 18 reduces the amount of heat exchange in the indoor heat exchanger 7 and lowers the minimum cooling capacity.

Then, the control unit 26 stops the flow of the refrigerant to the heat storage heat exchanger 18 during normal heating operation, and controls the flow of the refrigerant to the refrigerant pipe 15 side directly connected to the compressor 3. Then, when the defrosting operation (hereinafter referred to as defrosting / heating operation) is performed while continuing the heating operation, the refrigerant is switched and controlled so as to flow the refrigerant to the heat storage heat exchanger 18 of the heat storage device. Further, when returning from the defrosting / heating operation to the normal heating operation, the control unit 26 temporarily connects the heat storage heat exchanger 18 and the compressor 3 directly to the refrigerant pipe 15 (flow of the refrigerant during the normal heating operation). The refrigerant path is switched so that the refrigerant flows through both of the paths), and then the refrigerant path is switched from the heat storage heat exchanger 18 side to the refrigerant pipe 15 directly connected to the compressor 3. That is, it is controlled to gradually switch from the refrigerant path on the heat storage heat exchanger 18 side to the refrigerant path on the refrigerant pipe 15 side directly connected to the compressor 3. The details will be given later when the operation is explained.

[1-2. motion]
The operation of the air conditioner configured as described above will be described below. The arrows shown in FIGS. 1 to 3 indicate the flow of the refrigerant.

First, the operation of further lowering the minimum cooling capacity of the air conditioner that led to the present disclosure will be briefly described.

When the cooling operation is started, the refrigerant compressed by the compressor 3 is sent to the indoor heat exchanger 7 via the four-way valve 4, the outdoor heat exchanger 5, and the expansion valve 6 as shown by the arrow in FIG. .. The indoor heat exchanger 7 exchanges heat between the refrigerant and the indoor air to cool the room. The refrigerant after indoor cooling becomes a low-temperature gas refrigerant, and returns to the compressor 3 via the refrigerant pipe 12, the four-way valve 4, and the three-way valve 14 AB.

The temperature in the room drops while the above cooling operation is continued, the cooling capacity becomes the minimum cooling capacity determined by the minimum rotation speed of the compressor 3, and the cooling load is the same as a predetermined temperature difference (cooling load) arbitrarily determined. When it becomes equal to or less than that, the path of the three-way valve 14 is opened not only at the first outlet B but also at the second outlet C, and a part of the refrigerant returns to the compressor 3 via the heat storage heat exchanger 18. As a result, a part of the refrigerant is radiated by the heat storage heat exchanger 18 to exchange heat, and the amount of heat exchange with the indoor air performed by the indoor heat exchanger 7 is reduced. That is, the cooling capacity of the indoor heat exchanger 7 is lower than the minimum cooling capacity determined by the rotation speed of the compressor 3, and cooling is performed with a lower cooling capacity.

Therefore, it is possible to continue comfortable cooling by reducing the frequency of excessive cooling and thermo-on / off when the load is low.

Next, the normal heating operation and the defrosting / heating operation, which are the main points of the present disclosure, will be described.

When the heating operation is started, as shown by the arrow in FIG. 1, the refrigerant discharged from the compressor 3 passes through the refrigerant pipe 8 and reaches the indoor heat exchanger 7 from the four-way valve 4 via the refrigerant pipe 12. .. The indoor heat exchanger 7 heats by exchanging heat with the indoor air, and the condensed refrigerant exits the indoor heat exchanger 7, passes through the refrigerant pipe 11, reaches the expansion valve 6, and is decompressed by the expansion valve 6. The phase refrigerant reaches the outdoor heat exchanger 5 through the refrigerant pipe 10. The refrigerant evaporated by heat exchange with the outdoor air in the outdoor heat exchanger 5 reaches the three-way valve 14 via the four-way valve 4. In the three-way valve 14, during normal heating operation, the inlet A connected to the four-way valve 4 and the first outlet B directly connected to the compressor 3 communicate with each other, and the second outlet C connected to the heat storage heat exchanger 18 of the heat storage device is closed. It is controlled to the state of being controlled, and the refrigerant returns to the compressor 3 via the refrigerant pipe 15.

At this time, the heat generated by the compressor 3 is stored in the heat storage material 19 housed inside the heat storage tank 17 from the outer wall of the compressor 3.

When frost is formed on the outdoor heat exchanger 5 during the above normal heating operation and the frosted frost grows, the ventilation resistance of the outdoor heat exchanger 5 increases, the air volume decreases, and evaporation in the outdoor heat exchanger 5 occurs. The temperature drops. The piping temperature detecting means 24 of the outdoor heat exchanger 5 detects this decrease in evaporation temperature, and the control unit 26 outputs an instruction to switch from the normal heating operation to the defrosting / heating operation.

The instruction to switch to the defrosting / heating operation shifts from the normal heating operation to the defrosting / heating operation. At this time, the refrigerant during the normal heating operation described above is the indoor heat exchanger 7 as shown in FIG. It reaches the expansion valve 6 through the refrigerant pipe 11 and becomes a gas-liquid two-phase refrigerant decompressed by the expansion valve 6 with an appropriate throttle amount. This gas-liquid two-phase refrigerant heats the outdoor heat exchanger 5 through the refrigerant pipe 10, defrosts it, condenses it into a liquid phase, and then reaches the three-way valve 14 via the four-way valve 4.

The three-way valve 14 is controlled by the control unit 26 so that the inlet A connected to the four-way valve 4 communicates with the second outlet C connected to the heat storage heat exchanger 18 of the heat storage device during the defrosting / heating operation. As a result, the refrigerant from the second outlet C of the three-way valve 14 is depressurized by the capillary tube 20 to a low temperature, and the heat of the heat storage material 19 is absorbed and evaporated by the heat storage heat exchanger 18, and the refrigerant pipe 22 and the refrigerant pipe 15 are connected. It returns to the compressor 3 through.

The defrosting / heating operation is performed in this way, and when the defrosting of the outdoor heat exchanger 5 is completed, the evaporation temperature in the outdoor heat exchanger 5 rises, which is detected by the pipe temperature detecting means 24 and controlled by the control unit. From 26, an instruction to switch from the defrosting / heating operation to the normal heating operation is output.

When an instruction to switch to normal heating operation is given, in the air conditioner before this disclosure, the outlet C of the three-way valve 14 is switched to the first outlet B, and the refrigerant condensed and liquid-phased by the outdoor heat exchanger 5 is compressed at once. It switches to the normal heating operation in the form of returning to the machine 3. Here, as in the air conditioner of the present disclosure, the three-way valve 14 is provided in the piping path between the four-way valve 4 and the compressor 3, and the piping length between the first outlet B of the three-way valve 14 and the compressor 3 is provided. When is shortened, the pressure loss in the piping path is low, so that the liquid refrigerant flows to the compressor 3 almost as it is, and the amount of the liquid refrigerant returned to the compressor 3 increases as described in the above-mentioned knowledge section. do. Therefore, liquid compression occurs in the compressor 3, and there is a concern that the compressor 3 may be damaged.

However, in the air conditioner of the present disclosure, when switching to the normal heating operation, the control unit 26 does not switch the three-way valve 14 from the second outlet C to the first outlet B at once, but gradually shifts to the first outlet B. Control to switch.

Hereinafter, this will be described in detail with reference to FIGS. 4A and 4B.

FIG. 4A is a diagram showing the opening degree of the three-way valve AB when switching from the normal heating operation to the defrosting / heating operation, and FIG. 4B is a diagram showing the three-way valve A- when switching from the normal heating operation to the defrosting / heating operation. In the figure showing the C opening degree, the vertical axis shows the valve opening degree and the horizontal axis shows time.

First, during normal heating operation, the three-way valve 14 communicates with AB of the three-way valve 14 as shown by time a in FIG. 4A, but the control unit 26 performs defrosting / heating operation at time a. When an instruction is given, AB of the three-way valve 14 is closed and the communication is switched to AC of the three-way valve 14 as shown in FIG. 4B. Then, when the defrosting / heating operation is completed and an instruction is given to switch from the defrosting / heating operation to the normal heating operation at the time a, the control unit 26 communicates the AB of the three-way valve 14 to the normal heating operation. However, as shown in FIG. 4A, only a part of AB of the three-way valve 14 is communicated between the time a when switching to the defrosting / heating operation and the time c after a predetermined time, and the three-way valve 14 As shown in FIG. 4B, A to C are left in the open state as they are in a slightly squeezed state. After that, at time c, the AC of the three-way valve 14 is closed, and as shown in FIG. 4A, the AB of the three-way valve 14 is opened to the original opening and communicated, and the operation is switched to the normal heating operation. That is, switching from AC to AB of the three-way valve 14, in other words, returning the refrigerant to the compressor 3 via the auxiliary heat exchanger 18 from the refrigerant path during defrosting / heating operation to the compressor 3 Switching to the refrigerant path during normal heating operation, in which the refrigerant is directly returned via 15, is performed stepwise.

As a result, when switching from the defrosting / heating operation to the normal heating operation (from time a to time c), the outdoor heat exchanger 5 is liquefied and flows through the four-way valve 4 and the refrigerant pipe 13. Most of the liquid refrigerant flows as it is to the compressor 3 through the refrigerant path on the heat storage heat exchanger 18 side, and the remaining liquid refrigerant flows to the compressor 3 through AB of the three-way valve 14, and the refrigerant flows. It merges at the compressor inlet side of the pipe 15 and returns to the compressor 3.

Here, the length of the refrigerant pipe of the refrigerant path flowing from AC of the three-way valve 14 to the compressor 3 via the heat storage heat exchanger 18 side flows directly from AB of the three-way valve 14 to the compressor 3. Since it is longer than the length of the refrigerant pipe in the refrigerant path, the pressure drop is large and the refrigerant evaporates, and the liquid refrigerant ratio decreases. Therefore, even if a refrigerant having a high liquid-refrigerant ratio flows through the three-way valve 14 AB to the compressor 3, the refrigerant flows from the three-way valve 14 AC to the compressor 3 via the heat storage heat exchanger 18 side. The amount of liquid refrigerant that merges with the refrigerant having a small liquid-refrigerant ratio and returns to the compressor 3 is reduced. Therefore, it is possible to prevent the compressor 3 from causing liquid compression. Further, depending on the length of the refrigerant pipe length of the refrigerant path directly flowing from AB of the three-way valve 14 to the compressor 3 and the length of the refrigerant pipe of the refrigerant path directly flowing from AB of the three-way valve 14 to the compressor 3. Liquid compression of the compressor 3 can be prevented even without an accumulator.

Further, in the present embodiment, the capillary tube 20 is provided in the refrigerant pipe 21 which is the refrigerant path on the heat storage heat exchanger 18 side, and the liquid refrigerant in the refrigerant path on the heat storage heat exchanger 18 side returning to the compressor 3 is depressurized. Since the evaporation is promoted, the liquid return to the compressor 3 can be reduced more efficiently.

Further, in the present embodiment, since the path switching for preventing the liquid compression of the compressor 3 is performed by the three-way valve 14, the refrigerant path is switched stepwise with a simple configuration to prevent the compressor 3 from being damaged. be able to.

[1-3. Effect, etc.]
As described above, the air conditioner of the present disclosure includes a compressor 3, a four-way valve 4, an outdoor heat exchanger 5, an expansion valve 6, an indoor heat exchanger 7, a refrigeration cycle connected to the four-way valve 4, and the refrigeration. It has a control unit 26 that controls the operation of the cycle. The refrigeration cycle further includes an auxiliary heat exchanger 18 for heating the refrigerant, and the outdoor heat exchanger 5 to the compressor between the four-way valve 4 of the refrigeration cycle and the suction side of the compressor 3. Apart from the path for returning the refrigerant directly to 3, the path for returning the refrigerant from the outdoor heat exchanger 5 to the suction side of the compressor 3 via the auxiliary heat exchanger 18 and the path for returning the refrigerant directly to the compressor 3. A switching device 14 for switching between a path and a path for returning the refrigerant to the suction side of the compressor 3 via the auxiliary heat exchanger 18 is provided. The control unit 26 returns the refrigerant to the suction side of the compressor 3 via the auxiliary heat exchanger 18 during the defrosting / heating operation to melt the frost adhering to the outdoor heat exchanger 5, and also defrosts / heats. When switching back to the normal heating operation from the operation, the switching device 14 is controlled to gradually transfer the refrigerant from the outdoor heat exchanger 5 directly to the compressor 3 from the path on the auxiliary heat exchanger 18 side. It is configured to switch to the return route and control it.

As a result, a switching device 14 for switching the refrigerant path between the four-way valve 4 and the suction side of the compressor 3 is provided, and even if the pipe length from the switching device 14 to the compressor 3 during the heating operation is shortened. When switching from the defrosting / heating operation to the normal heating operation, the refrigerant changes from the path on the auxiliary heat exchanger 18 side during the defrosting / heating operation with a long pipe length to the other path, that is, the path directly returned to the compressor 3. Since the switching is performed in stages, it is possible to suppress the return of the liquid refrigerant to the compressor 3 at once. Therefore, damage to the compressor 3 due to liquid compression can be prevented, and a highly reliable air conditioner can be obtained.

Further, in the air conditioner of the present disclosure, the auxiliary heat exchanger 18 is composed of a heat storage heat exchanger 18 that stores the heat generated by the compressor 3 and uses it for defrosting during the heating operation.

As a result, it is possible to prevent damage to the compressor 3 due to liquid compression by utilizing the heat storage heat exchanger 18 used for defrosting during heating operation, and the air has good heating performance and high reliability at a reasonable cost. A harmonizer can be provided.

Further, in the air conditioner of the present disclosure, a capillary tube 20 is provided in a path for returning the refrigerant to the suction side of the compressor 3 via the auxiliary heat exchanger 18.

As a result, the liquid refrigerant on the heat storage heat exchanger 18 side returning to the compressor 3 is depressurized to promote evaporation, so that the liquid return to the compressor 3 can be reduced more efficiently.

Further, in the air conditioner of the present disclosure, the switching device 14 is composed of a three-way valve.

As a result, the path of the refrigerant flow can be switched with one three-way valve, and a highly reliable air conditioner can be provided by preventing damage to the compressor 3 due to liquid compression with a simple and inexpensive configuration.

Further, in the air conditioner of the present disclosure, the control unit 26 has a minimum cooling capacity determined by the minimum rotation speed of the compressor 3 during the cooling operation, and the cooling load is the same as or higher than a predetermined cooling load arbitrarily determined. When the following occurs, the switching device 14 is controlled so that a part of the refrigerant flowing from the indoor heat exchanger 7 via the four-way valve 4 flows to the path returned to the compressor 3 via the auxiliary heat exchanger 18. It is configured to be.

As a result, the minimum cooling capacity can be further reduced by using the heat storage heat exchanger 18 used for defrosting during heating operation, and heating can be continued while defrosting, and at least. By lowering the cooling capacity, it is possible to perform comfortable cooling with less thermo-off.

(Other embodiments)
As described above, the first embodiment has been described as an example of the technique disclosed in this application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. have been made. It is also possible to combine the components described in the first embodiment to form a new embodiment.

Therefore, some other embodiments will be exemplified below.

In the first embodiment, the three-way valve 14 is exemplified as the switching device 14 for switching the refrigerant path in order to prevent the liquid compression of the compressor 3, but this is a heat storage connected to the refrigerant pipe 13 from the four-way valve 4 by branching in a Y shape. An on-off valve may be provided in each of the refrigerant paths on the heat exchanger 18 side and the refrigerant pipe 15 side directly connected to the compressor 3 to serve as the switching device 14, and the compressor 3 may be provided by adjusting the opening degree of each on-off valve. Liquid compression can be prevented.

Further, in the first embodiment, the switching from the defrosting / heating operation to the normal heating operation by the switching device 14 is performed in one step from time a to time c, but it may be performed in a plurality of steps. The opening may be changed well or proportionally, and the "stepwise" of the present invention includes the case of "changing the opening proportionally".

Further, the case where the auxiliary heat exchanger 18 for defrosting is composed of the heat storage heat exchanger 18 incorporated in the heat storage tank 17 of the air conditioner is illustrated. However, it can also be realized in an air conditioner that does not have a heat storage tank 17. For example, the heat of the compressor 3 may be used as a configuration in which the auxiliary heat exchanger 18 is simply routed around the outer periphery of the compressor 3 which does not have the heat storage tank 17 shown in the first embodiment of the chamber. As described above, in the present invention, the configuration for preventing the liquid compression damage of the compressor that occurs when switching from the defrosting / heating operation to the normal heating operation does not necessarily have to be a heat storage type air conditioner having a heat storage tank 17. It is a thing.

Although the air conditioner according to the present invention has been described above by using each of the above embodiments, the present invention is not limited to this, and further various modifications are made within the scope of claims or the equivalent thereof. It can be replaced, added, omitted, etc.

The air conditioner of the present disclosure can prevent damage to the compressor due to liquid compression and enhance the reliability of the air conditioner, and can be widely applied to both household and commercial use.

1 Outdoor unit 2 Indoor unit 3 Compressor 4 Four-way valve 5 Outdoor heat exchanger 5a Outdoor fan 6 Expansion valve 7 Indoor heat exchanger 7a Indoor fan 8 Refrigerant piping 9 Refrigerant piping 10 Refrigerant piping 11 Refrigerant piping 12 Refrigerant piping 13 Refrigerant piping 14 Three-way valve (switching device)
15 Refrigerant piping 17 Heat storage tank 18 Heat storage heat exchanger (auxiliary heat exchanger)
20 Capillary tube 21 Refrigerant piping 22 Refrigerant piping 23 Outside air temperature detecting means 24 Piping temperature detecting means 25 Indoor temperature detecting means 26 Control unit

Claims (5)

An air conditioner having a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, an indoor heat exchanger, a refrigerating cycle connected to the four-way valve, and a control unit for controlling the operation of the refrigerating cycle. The refrigeration cycle further comprises an auxiliary heat exchanger for heating the refrigerant, and returns the refrigerant directly from the outdoor heat exchanger to the compressor between the four-way valve of the refrigeration cycle and the suction side of the compressor. Separately from the path, a path for returning the refrigerant from the outdoor heat exchanger to the suction side of the compressor via the auxiliary heat exchanger, a path for returning the refrigerant directly to the compressor, and a path via the auxiliary heat exchanger. A switching device for switching the path for returning the refrigerant to the suction side of the compressor is provided, and the control unit uses the auxiliary heat exchanger during the defrosting / heating operation to melt the frost adhering to the outdoor heat exchanger. The refrigerant is returned to the suction side of the compressor, and when switching back from the defrosting / heating operation to the normal heating operation, the switching device is controlled to gradually assist the refrigerant from the outdoor heat exchanger. An air conditioner configured to switch and control the path on the heat exchanger side to the path directly returned to the compressor. The air conditioner according to claim 1, wherein the auxiliary heat exchanger comprises a heat storage heat exchanger that accumulates heat generated by the compressor and uses it for defrosting during heating operation. The air conditioner according to claim 1 or 2, wherein a capillary tube is provided in a path for returning the refrigerant to the suction side of the compressor via an auxiliary heat exchanger. The air conditioner according to any one of claims 1 to 3, wherein the switching device is composed of a three-way valve. When the cooling capacity becomes the minimum cooling capacity determined by the minimum rotation speed of the compressor during the cooling operation and the cooling load becomes equal to or less than a predetermined cooling load arbitrarily determined, the control unit controls the switching device to control the room. The air according to any one of claims 1 to 4, wherein a part of the refrigerant flowing from the heat exchanger through the four-way valve is controlled to flow to the path returned to the compressor via the auxiliary heat exchanger. Harmony machine.

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