JP2017194201A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner which prevents freezing of drain water of an outdoor heat exchanger, and which suppresses deterioration of heating capacity.SOLUTION: An air conditioner includes: a refrigerant flow passage for connecting a compressor 35, a four-way selector valve 37, an indoor heat exchanger 23, an expansion mechanism 34 and an outdoor heat exchanger 33; and a hot gas bypass pipe 48 for connecting a refrigerant flow passage between the compressor 35 and the four-way selector valve 35, and a refrigerant flow passage between the indoor heat exchanger 23 and the expansion mechanism 34 or a refrigerant flow passage between the expansion mechanism 34 and the outdoor heat exchanger 33. The refrigerant flow passage is connected between the indoor heat exchanger 23 and the expansion mechanism 34, and has a hot gas pipe 45 located below the outdoor heat exchanger 33.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner having a freeze prevention pipe.

In the heating operation of the air conditioner, in order to melt the frost generated in the outdoor heat exchanger, a defrost cycle operation that is a refrigeration cycle operation opposite to the heating cycle may be performed. By the operation of the defrost cycle, the frost melting water flows down from the outdoor heat exchanger, is collected in a drain pan disposed below the outdoor heat exchanger, and is drained from the drain hole.
However, in an extremely cold environment where the outside air temperature is always below freezing point, the drain water melted by the operation of the defrost cycle is frozen again in the drain pan and gradually grows and grows on the drain pan. It may cause destruction of heat exchangers and outdoor unit fans.

For this reason, various methods for preventing refreezing of drain water have been devised.
For example, Patent Document 1 describes that “a part of the refrigerant pipe is disposed in an outdoor drain pan to suppress freezing of drain water accumulated in the outdoor drain pan during heating operation”.
Patent Document 2 describes that “at the time of defrosting operation, high temperature refrigerant discharged from the compressor is supplied in the order of the hot gas pipe disposed in the drain pan and the evaporator to perform defrosting”.

Japanese Patent Laid-Open No. 60-60466 JP-A-8-219599

According to the prior art described in Patent Document 1 described above, in the air conditioner, a part of the refrigerant pipe is disposed to prevent freezing of the drain water accumulated in the outdoor drain pan, so that the drain pan is frozen to some extent. Although it can be prevented, the amount of heat required to prevent the drain water from freezing at a low outside air temperature increases, so that there is a problem of freezing in a situation where the low outside air temperature condition continues.
Further, in the prior art described in Patent Document 2, the drain water is frozen even at a low outside temperature by supplying the high-temperature refrigerant discharged from the compressor during the defrosting operation to the hot gas pipe disposed in the drain pan. Although it can be prevented, if the heating operation is performed in a state where the defrosting operation is completed and the high-temperature refrigerant is not supplied to the hot gas pipe, the drain water is frozen. In addition, increasing the number of times the high-temperature refrigerant is supplied to the hot gas pipe in order to avoid freezing of the drain water reduces the heating capacity at low outside temperatures, and it becomes impossible to ensure indoor comfort by heating operation. Become.
Further, if the frequency of the defrosting operation that performs the same refrigeration cycle operation as the cooling operation is increased, the supply amount of the high-temperature and high-pressure gas refrigerant to the indoor heat exchanger decreases, so that it becomes difficult to maintain the indoor temperature. You may not be able to maintain comfort.

  The objective of this invention is providing the air conditioner which suppresses the fall of the heating capability relevant to freezing of the drain water of an outdoor heat exchanger.

  In order to solve the above problems, an air conditioner according to the present invention includes a compressor, a four-way switching valve, an indoor heat exchanger, an expansion mechanism, and a refrigerant flow path connecting an outdoor heat exchanger, the compressor, and the four-way switching valve. And the refrigerant flow path between the indoor heat exchanger and the expansion mechanism or the refrigerant flow path between the expansion mechanism and the outdoor heat exchanger. A gas bypass pipe, and the refrigerant flow path has a hot gas pipe connected between the indoor heat exchanger and the expansion mechanism and positioned below the outdoor heat exchanger.

  According to the present invention, it is possible to provide an air conditioner that can suppress a decrease in heat exchange capacity of an outdoor heat exchanger and maintain a comfortable indoor temperature even in a heating operation under a low outside air temperature condition.

It is a whole block diagram of an air conditioner. It is a block diagram of the refrigerating cycle of an Example. It is a control flow regarding the defrosting of the outdoor heat exchanger of a control part. It is a figure which shows the cross section of an outdoor unit (outdoor heat exchanger). It is a block diagram of the refrigerating cycle at the time of providing a hot gas pipe | tube in an outdoor exchanger. It is a block diagram of the refrigerating cycle which shows the other example of arrangement | positioning of a hot gas bypass pipe. It is a block diagram of the refrigerating cycle of the air conditioner with a reheat dehumidification function.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Drawing 1 is a figure showing the whole air conditioner 1 composition of an example.
The air conditioner 1 is a separate air conditioner in which an indoor unit 2 and an outdoor unit 3 are connected via a refrigerant pipe 4, electrical wiring, signal wiring, and the like, and is operated by a remote controller 5.

Example 1
First, an embodiment in which a hot gas pipe 45 is provided in a drain pan (not shown) will be described with reference to FIG. 2 in order to prevent the drain water of the drain pan of the outdoor unit 3 from freezing. FIG. 2 is a diagram showing the configuration of the refrigeration cycle of the present embodiment.

  In the refrigeration cycle of FIG. 2, an accumulator 36, a compressor 35, a four-way switching valve 37, an indoor heat exchanger 23, a decompressor (expansion mechanism) 34, and an outdoor heat exchanger 33 are connected so that the refrigerant circulates. The cooling cycle and the heating cycle are switched according to the switching state of the four-way switching valve 37 which is a flow path switching valve. The four-way switching valve 37 in FIG. 2 indicates the state of the refrigerant flow path of the heating cycle.

The hot gas pipe 45 connects between the liquid pipe 44 of the indoor heat exchanger 23 and the decompressor 34 and is disposed in a drain pan of the outdoor unit 3 (not shown).
The drain pan of the outdoor unit 3 is a dish that is provided below the outdoor heat exchanger 33 of the outdoor unit 3 and receives the frost-melted water of the outdoor heat exchanger 33. Drain water (melted water) that is frost melting water is drained out of the outdoor unit 3.

Here, the heating cycle of the refrigeration cycle of FIG. 2 will be described.
In the heating cycle, the refrigerant is compressed into a high-temperature and high-pressure gas state by the compressor 35. This gas refrigerant is supplied to the indoor heat exchanger 23 by the four-way switching valve 37 via the use side gas pipe 43.
The indoor heat exchanger 23 is ventilated by the indoor fan 21 driven by the indoor air blower motor 22, and heat is exchanged between the indoor air and the refrigerant. Thereby, indoor heating is performed.

The high-temperature and high-pressure gaseous refrigerant passes through the indoor heat exchanger 23 acting as a condenser and enters a liquid or gas-liquid mixed state. Then, the refrigerant exits the indoor heat exchanger 23 and reaches the decompressor 34 through the liquid pipe 44 and the hot gas pipe 45 disposed in the drain pan. As described above, the hot gas pipe 45 is formed by a part of the refrigerant pipe connecting the decompressor 34 and the indoor heat exchanger 23.
The liquid or gas-liquid mixed refrigerant is decompressed by the decompressor 34 and becomes a low-pressure liquid or gas-liquid mixed refrigerant.

The refrigerant that has been in a low-pressure liquid or gas-liquid mixed state by the decompressor 34 flows into the outdoor heat exchanger 33 through the heat source side liquid pipe 46.
In the outdoor heat exchanger 33, ventilation is performed by the outdoor fan 31 driven by the outdoor blower motor 32, and heat is exchanged between the outdoor air and the refrigerant.

  At this time, the outdoor heat exchanger 33 acts as a refrigerant evaporator, and the outdoor air is cooled due to the heat of vaporization of the refrigerant. Depending on the case, it may become 0 degrees C or less and may form frost on the heat-transfer surface of the outdoor heat exchanger 33. FIG. In particular, this phenomenon becomes prominent when the temperature of the outside air is low and the humidity is high, and the flow of outdoor air through the outdoor heat exchanger 33 is hindered by frost adhering to the ventilation surface of the outdoor air.

When the ventilation rate of the outdoor heat exchanger 33 decreases due to frost formation, the temperature of the outdoor heat exchanger 33 further decreases, and frost is more likely to be formed. Thus, the amount of frost formation in the outdoor heat exchanger 33 continues to increase, the amount of heat pumped from the outdoor air by the air conditioner 1 decreases, the heating capacity decreases, the room cannot be heated sufficiently, and the heating function is lost. End up. For this reason, the driving | operation of the defrost cycle which removes the frost of the outdoor heat exchanger 33 is needed.
This defrost cycle will be described later.

Returning to the description of the heating cycle of the refrigeration cycle in FIG. 2, the refrigerant in a low-pressure gas state in the outdoor heat exchanger 33 acting as an evaporator flows into the four-way switching valve 37 through the heat source side gas pipe 47.
As shown in FIG. 2, the four-way switching valve 37 is connected so that the refrigerant flows between the discharge pipe 42 and the use side gas pipe 43 in the heating cycle, and between the heat source side gas pipe 47 and the suction pipe 41. Therefore, the refrigerant that has been in a low-pressure gas state in the outdoor heat exchanger 33 flows into an accumulator 36 that performs gas-liquid separation of the refrigerant.
Then, the gas refrigerant returns from the accumulator 36 to the compressor 35, and the refrigerant circulates.

Here, the configuration of the refrigeration cycle in FIG. 2 will be described in more detail.
The outdoor heat exchanger 33 and the indoor heat exchanger 23 are configured by refrigerant pipes and heat transfer fins, and a refrigerant circuit formed by the refrigerant pipes is divided into a plurality of parts and connected in parallel. This refrigerant circuit is divided into a plurality of parts.
The decompressor 34 decompresses the refrigerant from the outdoor heat exchanger 33 during cooling of the cooling cycle, and decompresses the refrigerant from the indoor heat exchanger 23 during heating operation of the heating cycle. The decompressor 34 of the present embodiment is configured by an expansion valve whose throttle opening can be controlled, for example, an electric type.

The indoor unit 2 provided with the indoor heat exchanger 23 is provided with an indoor fan 21 that circulates indoor air through the indoor heat exchanger 23, and an indoor air blower motor 22 that drives the indoor fan 21. Exchanges heat between indoor air.
More specifically, the indoor heat exchanger 23 acts as a high-pressure side heat exchanger (condenser) of the heating cycle during the heating operation of the air conditioner 1, and the low pressure of the cooling cycle during the cooling operation of the air conditioner 1. Acts as a side heat exchanger (evaporator).
In this embodiment, a cross flow fan is used as the indoor fan 21.

The outdoor unit 3 provided with the outdoor heat exchanger 33 is provided with an outdoor fan 31 that allows outdoor air to flow through the outdoor heat exchanger 33, and an outdoor fan motor 32 that drives the outdoor fan 31. Heat exchange between the air and outdoor air.
More specifically, the outdoor heat exchanger 33 acts as a low-pressure side heat exchanger (evaporator) of the heating cycle during the heating operation of the air conditioner 1, and the high pressure of the cooling cycle during the cooling operation of the air conditioner 1. Acts as a side heat exchanger (condenser).
In this embodiment, an axial fan is used as the outdoor fan 31.

Next, a control system in the refrigeration cycle of FIG. 2 will be described.
The refrigeration cycle of the air conditioner 1 of the present embodiment is controlled by the control unit 10.
The control unit 10 includes an indoor unit refrigerant temperature detection sensor 11, an outdoor unit refrigerant temperature detection sensor 12, and an outdoor temperature detection based on operation instructions such as cooling operation, heating operation, and temperature setting of the remote controller 5 (see FIG. 1). The compressor 35, the four-way switching valve 37, the outdoor blower motor 32, and the indoor blower motor 22 are controlled according to the detection results of the sensor 13 and the room temperature detection sensor 14.
Specifically, the indoor unit refrigerant temperature detection sensor 11 detects the temperature of the refrigerant in the indoor heat exchanger 23 during heating operation, and the outdoor unit refrigerant temperature detection sensor 12 is the temperature of the refrigerant in the outdoor heat exchanger 33 during heating operation. Is detected, and it is determined whether or not an operation of a defrost cycle described later is necessary.

Below, a defrost cycle is demonstrated.
As described above, the outdoor heat exchanger 33 is frosted during the heating operation of the air conditioner 1, the function of the outdoor heat exchanger 33 as an evaporator is reduced, and the heating capacity of the air conditioner 1 is reduced. There is. The control unit 10 according to the present embodiment performs the heating cycle operation for a predetermined time or more when the refrigerant inlet temperature of the outdoor heat exchanger 33 detected by the outdoor unit refrigerant temperature detection sensor 12 is lower than a predetermined temperature. In this case, it is considered that the frost has reached a predetermined amount, and the next defrost cycle is performed.

In this defrost cycle, the four-way switching valve 37 is connected to the discharge pipe 42 of the compressor 35 and the heat source side gas pipe 47, contrary to the heating cycle, and the suction pipe 41 and the use side gas pipe 43 of the accumulator 36 are connected. Switch to connect.
Then, the compressor 35 is operated, and the high-temperature and high-pressure gas refrigerant flows into the outdoor heat exchanger 33 via the four-way switching valve 37. Since the refrigerant that has entered the outdoor heat exchanger 33 has a high temperature and a high pressure, it melts frost adhering to the outdoor heat exchanger 33. The molten water is dropped below the outdoor heat exchanger 33.
At this time, the outdoor air blowing motor 32 is operated or stopped at a low speed, and the indoor air blowing motor 22 is also operated or stopped at a low speed.

The high-temperature and high-pressure gas refrigerant that has flowed into the outdoor heat exchanger 33 is cooled and condensed by heat exchange with frost formed on the heat transfer surface and melted frost (drain water). Become.
Next, the refrigerant enters the decompressor 34, becomes a low-pressure liquid or gas-liquid mixed refrigerant, and flows into the indoor heat exchanger 23. The indoor heat exchanger 23 acts as an evaporator, and the refrigerant enters a gas state and returns to the compressor 35.
Thereby, a refrigerant circulates through a refrigerating cycle and a defrost cycle is operated.

  The control unit 10 according to the present embodiment is configured such that the refrigerant inlet temperature of the outdoor heat exchanger 33 detected by the outdoor unit refrigerant temperature detection sensor 12 exceeds a predetermined temperature or the defrost cycle is operated for a predetermined time or more. In addition, it is considered that the frost has disappeared, the operation of the defrost cycle is terminated, and the operation returns to the heating operation. As a result, the outdoor heat exchanger 33 immediately after the completion of the defrosting removes the frost that has interfered with the heat transfer, so that the heat transfer from the outside air to the refrigerant is performed smoothly, and the heat exchange capability is improved. It recovers and it is possible to suppress a decrease in indoor heating capacity.

The frost-melted water (drain water) of the outdoor heat exchanger 33 by the above-mentioned defrost cycle accumulates in the drain pan. During the heating operation, the drain pan is provided with the hot gas pipe 45 connected to the liquid pipe 44 through which the high-pressure liquid or gas-liquid mixed refrigerant flows, so that the drain water is not heated and frozen.
However, under conditions where the outside air temperature is extremely low (extremely low temperature conditions) such as in a cold region, the drain water collected in this drain pan may become 0 ° C. or lower and freeze. If the drain water freezes, the outdoor heat exchanger 33 may be damaged.

For this reason, in the air conditioner 1 of the embodiment, during the heating operation, a high-temperature refrigerant is appropriately supplied to the hot gas pipe 45 according to the state of the outside air temperature, and the amount of heat is compensated so as not to freeze the drain water. .
Specifically, a hot gas bypass pipe 48 that connects the discharge pipe 42 of the compressor 35 to the liquid pipe 44 is provided. The high-temperature and high-pressure gas state refrigerant of the compressor 35 is supplied to the liquid pipe 44 by a bypass on-off valve (open / close mechanism) 49 of the hot gas bypass pipe 48.

The bypass opening / closing valve (opening / closing mechanism) 49 is configured by an electromagnetic opening / closing valve, and when the outside air temperature detected by the controller 10 by the outside air temperature detection sensor 13 is lower than a predetermined value, the bypass opening / closing valve 49 opens for a certain period. The high-temperature and high-pressure gas refrigerant is supplied to the liquid pipe 44 (hot gas pipe 45).
As a result, the amount of heat necessary to prevent the drain water from being frozen in the hot gas pipe 45 can be supplied even under conditions where the outside air temperature is extremely low (extremely low temperature conditions) such as in a cold region, so that the drain water collected in the drain pan is frozen. Since the drain water can be discharged without clogging the discharge port, a decrease in heating capacity can be suppressed.
In the present embodiment, the bypass on-off valve 49 is an electromagnetic on-off valve, but it may be an expansion valve capable of controlling the electromagnetic throttle opening, for example, an electric type.

By branching the high-temperature and high-pressure gas refrigerant of the compressor 35 to the hot gas bypass pipe 48 for a certain period of heating operation, the amount of refrigerant supplied to the indoor heat exchanger 23 is reduced. For this reason, the arrival time until the room temperature detected by the room temperature detection sensor 14 reaches the heating set temperature set by the remote controller 5 or the like may be prolonged.
In the following description of the embodiments, when the room temperature detected by the room temperature detection sensor 14 becomes a value in a predetermined temperature range centered on the heating set temperature set by the remote controller 5 or the like, the room temperature is the set temperature. It has reached the state.

For this reason, the control unit 10 of the present embodiment supplies the high-temperature refrigerant to the hot gas pipe 45 when the outside air temperature is lower than a predetermined value during the heating operation in which the set room temperature is maintained after reaching the set room temperature by the heating operation. Thus, the bypass on-off valve 49 is controlled to open for a certain period.
By supplying the high-temperature refrigerant to the hot gas pipe 45 after reaching the set room temperature, even if the high-temperature refrigerant flowing through the indoor heat exchanger 23 decreases and the amount of heat supplied decreases, the set room temperature is reached. Can be maintained. Therefore, it is possible to prevent the drain water from freezing while maintaining the set room temperature.
Specifically, the drive period and drive rate of the compressor 35 are adjusted so as to supplement the decrease in the high-temperature refrigerant flowing through the indoor heat exchanger 23.

In addition, the control unit 10 opens the bypass on-off valve 49 and supplies the high-temperature refrigerant to the hot gas pipe 45 in order to compensate for a decrease in the amount of heat of the high-temperature refrigerant flowing in the indoor heat exchanger 23. The rotational speed of the compressor 35 may be controlled to control the decompressor 34 so that the discharge temperature becomes higher.
Thereby, freezing of the drain water of a drain pan can be prevented, without reducing the heating capability of the indoor heat exchanger 23. FIG.

After reaching the above heating set temperature, a combination of supplying the high-temperature and high-pressure gas refrigerant to the hot gas pipe 45 by the hot gas bypass pipe 48 and increasing the discharge temperature of the gas refrigerant of the compressor 35 is combined. May be executed.
That is, when the outside air temperature detected by the outside air temperature detection sensor 13 is lower than the first predetermined temperature, the hot gas bypass pipe 48 supplies the high-temperature and high-pressure gas refrigerant to the hot gas pipe 45, and the outside air temperature is the first temperature. When the temperature is lower than the second predetermined temperature lower than the predetermined temperature, the discharge temperature of the gas refrigerant of the compressor 35 is set to a high temperature so as to be supplied to the hot gas pipe 45.
Thereby, the increase in the power consumption of the air conditioner 1 can be suppressed, and the drain water of the drain pan can be prevented from freezing while heating at a predetermined temperature.

As described above, the controller 10 supplies the high-temperature and high-pressure gas refrigerant to the hot gas pipe 45 by the hot gas bypass pipe 48 during the heating operation to maintain the set room temperature after reaching the set room temperature of the heating operation. Specifically, the following control is performed.
The compressor 35 during the heating operation that maintains the set room temperature is repeatedly driven and stopped. When the compressor 35 is stopped, the refrigerant is not circulated, but the ratio of the driving time of the compressor 35 can be controlled. Therefore, when the outside air temperature is lower than the predetermined value, the driving time of the compressor 35 can be increased, and the high-temperature and high-pressure gas refrigerant supplied to the hot gas pipe 45 can be secured.
That is, the control unit 10 increases the drive time of the compressor 35 and opens the bypass opening / closing valve 49 in the control state in which the thermo-off for stopping the compressor 35 during the heating operation is performed. Thereby, the high-temperature refrigerant is supplied to the hot gas pipe 45.

Next, the configuration and arrangement of the hot gas bypass pipe 48 will be described in detail.
As described above, the hot gas pipe 45 is supplied with the high-temperature and high-pressure gas refrigerant of the compressor 35 that is divided into the hot gas bypass pipe 48 and the indoor heat exchanger 23.
Since the high-temperature and high-pressure gas refrigerant supplied from the hot gas bypass pipe 48 does not contribute to heating, it is desirable that the flow rate be the minimum necessary to prevent the drain water from freezing.

The flow ratio of the gas refrigerant branched into the hot gas bypass pipe 48 is determined by the pressure loss of the refrigerant flow path on the hot gas bypass pipe 48 side and the pressure loss of the refrigerant flow path on the indoor heat exchanger 23 side.
However, the installation height and the channel length of the indoor heat exchanger 23 that affect the refrigerant flow rate of the refrigerant channel on the indoor heat exchanger 23 side also vary depending on the installation status. Further, the required flow rate of the gas refrigerant in the hot gas bypass pipe 48 also varies depending on the outside air temperature. The flow rate ratio of the gas refrigerant branched to the hot gas bypass pipe 48 varies depending on the installation conditions of the indoor heat exchanger 23 and the outside air temperature.

However, the length of the hot gas bypass pipe 48 is shorter than the refrigerant flow path length on the indoor heat exchanger 23 side. Therefore, the pipe diameter of the hot gas bypass pipe 48 is set to be equal to or smaller than the pipe diameter of the use side gas pipe 43 or the liquid pipe 44.
In addition, since the high-temperature and high-pressure gas refrigerant flows through the hot gas bypass pipe 48, the installation height of the hot gas bypass pipe 48 is not limited.

In the above description, the bypass opening / closing valve (opening / closing mechanism) 49 is configured as an electromagnetic opening / closing valve, but the bypass opening / closing valve (opening / closing mechanism) 49 may be configured as an expansion valve whose electromagnetic throttle opening degree can be controlled. Good. In this case, when supplying the gas refrigerant from the hot gas bypass pipe 48 to the hot gas pipe 45, the throttle opening degree is adjusted, and the pressure loss of the hot gas bypass pipe 48 is reduced to the refrigerant flow on the indoor heat exchanger 23 side. Within α times the road pressure loss (α is 5).
Thereby, the flow ratio (flow velocity ratio) of the gas refrigerant branched to the hot gas bypass pipe 48 can be controlled, and the thermal efficiency when preventing refreezing of the drain water can be improved.

By the way, when the bypass opening / closing valve 49 is opened or the throttle opening is opened, the gas refrigerant flows through the hot gas bypass pipe 48, whereby the flow rate of the gas refrigerant fluctuates. As a result, pressure fluctuation occurs at the connection point between the hot gas bypass pipe 48 and the liquid pipe 44. Due to this pressure fluctuation, the gas-liquid two-phase refrigerant in the liquid pipe 44 may flow backward to the hot gas bypass pipe 48.
For this reason, the hot gas bypass pipe 48 is disposed vertically above the liquid pipe 44 to prevent the liquid refrigerant from flowing back to the hot gas bypass pipe 48.

FIG. 3 is a control flow related to defrosting of the outdoor heat exchanger 33 of the control unit 10.
First, the control unit 10 determines whether or not the air conditioner 1 is instructing a heating operation by the remote controller 5 or the like (S301).
If the operation instruction for the heating operation is being performed (Yes in S301), the process proceeds to step S302. If the operation instruction during heating is not in progress (No in S301), the process is terminated.

In step S302, the heating cycle operation of the heating operation of the air conditioner 1 described in FIG. 2 is performed.
Then, the inlet temperature of the refrigerant outdoor heat exchanger 33 is detected by the outdoor unit refrigerant temperature detection sensor 12, and it is determined whether or not the detected temperature is lower than a predetermined temperature (S303). If the detected temperature is equal to or higher than the predetermined temperature (No in S303), it is assumed that the outdoor heat exchanger 33 is not frosted, and the process proceeds to step S309.

If the detected temperature of the refrigerant is lower than the predetermined temperature (Yes in S303), it is determined whether the operation of the heating cycle is performed for a predetermined time or more (S304), and if the operation time of the heating cycle is less than the predetermined time (No in S304). ), Assuming that the frost amount of the outdoor heat exchanger 33 has not reached the predetermined amount, the process proceeds to step S309.
Here, the determination amount of the frost formation amount means an amount indicating whether or not the ventilation of the outdoor heat exchanger 33 is hindered, and may not be an actual frost formation amount.

  If the heating cycle has been operated for a predetermined time or longer in step S304 (Yes in S304), the frosting amount of the outdoor heat exchanger 33 reaches a predetermined amount, and ventilation of the outdoor heat exchanger 33 is hindered. As a thing, it progresses to step S305, a defrost operation (defrost cycle operation | movement) is started, and it progresses to step S306.

In step S306, the inlet temperature of the refrigerant outdoor heat exchanger 33 is detected by the outdoor unit refrigerant temperature detection sensor 12, and it is determined whether or not the detected temperature is equal to or higher than a predetermined temperature (S306). If the detected temperature is equal to or higher than the predetermined temperature (Yes in S306), the process proceeds to step S308.
In step S308, it is considered that the defrosting has ended, the operation of the defrosting cycle is ended, and the operation returns to the operation of the heating cycle.

  In step S306, if the detected temperature is lower than the predetermined temperature (No in S306), it is determined whether or not the defrost cycle is performed longer than the predetermined time (S307), and the defrost cycle is longer than the predetermined time. If so (Yes in S307), the process proceeds to step S308 to return to the operation of the heating cycle.

  In step S307, if the defrost cycle has not been performed for longer than the predetermined time (No in S307), it is determined that the defrost has not ended, and the process returns to step S305 to continue the operation of the defrost cycle.

  When returning to the heating cycle operation in step S308, the room temperature is detected by the room temperature sensor 14, and it is determined whether or not the detected room temperature is a set temperature (S309). When the room temperature is not the set temperature (No in S309), the process returns to step S301 and the operation is continued.

In step S309, when the room temperature is the set temperature (Yes in S309), the outside air temperature is detected by the outside air temperature detection sensor 13, and it is determined whether or not the detected outside air temperature is lower than the predetermined first temperature. Determination is made (S310).
If the outside air temperature is equal to or higher than the first temperature in step S310 (No in S310), the process returns to step S301 and the operation is continued. When the outside air temperature is lower than the first temperature (Yes in S310), the process proceeds to step S311.

  In step S311, it is determined whether or not the outside air temperature is lower than a second temperature lower than the first temperature. If the outside air temperature is equal to or higher than the second temperature (No in S311), the process proceeds to step S313, the bypass on-off valve 49 is opened for a certain time, and the compressor 35 is connected from the hot gas bypass pipe 48 to the liquid pipe 44. Supply high-temperature and high-pressure gas refrigerant. As a result, the high-temperature refrigerant flows through the hot gas pipe 45 disposed in the drain pan, so that the drain water does not freeze. Then, it returns to step S301 and continues operation.

In step S311, when the outside air temperature is lower than the second temperature (Yes in S311), the rotation speed of the compressor 35 is controlled so that the temperature of the refrigerant discharged from the compressor 35 rises, and the decompressor 34 Is controlled (S312). In step S313, the high-temperature and high-pressure gas refrigerant of the compressor 35 is supplied from the hot gas bypass pipe 48 to the liquid pipe 44 for a predetermined time (S313).
At this time, when the supply of the high-temperature and high-pressure gas refrigerant in S313 for a certain period of time is completed, the compressor 35 is returned to the original driving condition.
When the supply of the high-temperature and high-pressure gas refrigerant from the hot gas bypass pipe 48 in step S313 is completed for a predetermined time, the process returns to step S301 and the operation is continued.

  As explained above, the hot gas bypass pipe is provided between the discharge side of the compressor and the refrigerant pipe connected between the hot gas pipe and the indoor heat exchanger, and the bypass opening / closing valve is provided in the hot gas bypass pipe. By appropriately supplying the refrigerant to the hot gas pipe, the drain water can be prevented from freezing and the heating capacity can be prevented from lowering even under extremely low outside air temperature conditions (extremely low temperature conditions) such as in cold districts.

  In the above description, the cooling operation of the air conditioner 1 of the embodiment has not been particularly described. However, the four-way switching valve 37 is switched to change the circulation direction of the refrigerant, the outdoor heat exchanger 33 is used as a condenser, and the indoor heat exchanger is changed. Needless to say, the cooling cycle may be formed by using 23 as an evaporator.

At this time, the bypass on-off valve 49 is closed so that the high-temperature and high-pressure gas refrigerant of the compressor 35 does not flow through the hot gas bypass pipe 48. Thereby, since the hot gas bypass pipe 48 becomes a closed pipe, the liquid refrigerant is stored, and the utilization efficiency of the refrigerant is lowered.
In order to prevent a decrease in the utilization efficiency of the refrigerant, it is desirable to shorten the length of the hot gas bypass pipe 48. Further, an open / close valve may be provided on the liquid gas pipe 44 side of the hot gas bypass pipe 48 so that the open / close valve is closed during the cooling cycle operation.

Example 2
In the air conditioner 1 of the above embodiment, the hot gas pipe 45 is disposed in the drain pan so that the melt water (drain water) due to the defrost cycle does not freeze in the drain pan, and when the outside air temperature is low, The example in which the high-temperature and high-pressure gas refrigerant is supplied through the hot gas pipe 45 has been described.
Next, unlike the embodiment in which the drain water of the drain pan is heated and frozen, an embodiment in which the molten water (drain water) is heated to prevent freezing in the drain pan will be described.

FIG. 4 is a view showing a cross section of the outdoor unit 3 (outdoor heat exchanger 33) of the present embodiment.
In the four vertically (two-stage) refrigerant pipes passing through the heat transfer fins of the outdoor heat exchanger 33 of the outdoor unit 3, the liquid exiting the indoor heat exchanger 23 or the refrigerant in a gas-liquid mixed state flows. A hot gas pipe 45 is provided. In FIG. 4, four (two-stage) hot gas pipes 45 are shown, but the number is not limited to this.
A drain pan 50 that receives the frost melting water is disposed in a vertically lower portion of the outdoor heat exchanger 33, and the frost melting water (drain water) is collected in the drain pan 50 and drained to the outside of the outdoor unit 3.

The frost generated on the surface of the heat transfer fins of the outdoor heat exchanger 33 during the heating operation of the air conditioner 1 is melted by the operation of the defrost cycle, and this molten water hangs down on the surface of the heat transfer fins and drops on the drain pan 50. To do. At this time, since the refrigerant pipe vertically below the heat transfer fin of the outdoor heat exchanger 33 is the hot gas pipe 45, the refrigerant heat of the hot gas pipe 45 is transferred to the heat transfer fin of the outdoor heat exchanger 33. doing. The molten water absorbs the refrigerant heat from the heat transfer fin surface of the outdoor heat exchanger 33 and rises in temperature.
Since the molten water (drain water) that has absorbed the refrigerant heat is dripped onto the drain pan 50, it does not freeze directly and is drained to the outside of the outdoor unit 3.

  Although details will be described later, under conditions where the outside air temperature is extremely low (extremely low temperature condition) such as a cold district, the high-temperature and high-pressure gas state refrigerant of the compressor 35 is bypassed and supplied to the hot gas pipe 45. Thereby, the calorie | heat amount which molten water (drain water) absorbs heat | fever increases, and freezing of molten water (drain water) can be prevented.

  Even if the drain water freezes in the drain pan 50 and an ice column grows upward, the vertical lower portion of the outdoor heat exchanger 33 is heated by the refrigerant in the hot gas pipe 45, so that the ice column melts. For this reason, destruction of an outdoor heat exchanger or an outdoor unit fan is not caused.

FIG. 5 is a diagram illustrating a configuration of the refrigeration cycle of the air conditioner 1 of the present embodiment.
The configuration diagram of the refrigeration cycle in FIG. 2 is that the hot gas pipe 45 is disposed in the outdoor heat exchanger 33, and the decompressor (expansion mechanism) 34 a is between the hot gas pipe 45 and the liquid pipe 44. Different points are provided.

  The refrigerant flow and the control method in the heating cycle and defrost cycle in the configuration of the refrigeration cycle in FIG. 5 are the same as those described in FIG. 2 and FIG.

In the present embodiment, as described above, the hot gas pipe 45 is disposed in the outdoor heat exchanger 33. When decompression is performed by the decompressor 34 during the operation of the cooling cycle, the refrigerant that has flowed through the outdoor heat exchanger 33 that acts as a condenser and is in a liquid or gas-liquid mixed state is heated outdoor by the hot gas pipe 45 after decompression. Returning to the heat exchanger 33, the refrigerant is vaporized by exchanging heat with the outside air, so that the liquid refrigerant supplied to the outdoor heat exchanger 33 is reduced and the cooling capacity is lowered.
For this reason, a decompressor 34a is provided between the hot gas pipe 45 and the liquid pipe 44 so as to decompress the refrigerant in the liquid or gas-liquid mixed state.

Specifically, in the heating cycle, the control unit 10 controls the decompressor 34a to open and allows the refrigerant to flow therethrough, and controls the valve opening degree of the decompressor 34 to perform refrigerant decompression. Then, in the cooling cycle or the defrost cycle, the control unit 10 controls the decompressor 34 to be opened to allow the refrigerant to flow, and controls the valve opening degree of the decompressor 34a to perform the decompression of the refrigerant.
Thereby, the fall of the cooling capability by the vaporization of a liquid refrigerant by having arrange | positioned the hot gas pipe | tube 45 in the outdoor heat exchanger 33 is prevented.

As described above, according to the air conditioner 1 of the present embodiment, it is possible to prevent the drain water from being frozen while maintaining the set room temperature, to prevent the heating capacity from being lowered due to the freezing of the drain water, The comfort of the machine can be improved.
Further, as shown in FIG. 4, by providing the hot gas pipe 45 so as to penetrate through the heat transfer fins of the outdoor heat exchanger 33, a fixture for fixing the refrigerant pipe of the hot gas pipe 45 is not necessary. Thereby, manufacturing cost can be suppressed at low cost.

Example 3
In the above embodiment, a configuration has been described in which a high-temperature and high-pressure gas refrigerant is supplied to the hot gas pipe 45 by the hot gas bypass pipe 48 to prevent refreezing of the molten water (drain water) in the defrost cycle. Next, the configuration of another refrigeration cycle of the air conditioner 1 will be described with reference to FIG.

In the configuration of the refrigeration cycle of the air conditioner 1 in FIG. 6, a hot gas bypass pipe 48 that supplies a high-temperature and high-pressure gas refrigerant is connected to a heat source side liquid pipe 46 between the decompressor 34 and the outdoor heat exchanger 33. ing. That is, the connection destination of the hot gas bypass pipe 48 is different from the configuration of the refrigeration cycle of FIGS.
The other configurations are the same as those shown in FIGS. 2 and 5 and thus will not be described.
Next, the operation of the refrigeration cycle in FIG. 6 will be described.

  In the air conditioner 1 of FIGS. 2 and 5, the four-way switching valve 37 is switched to the direction of the cooling cycle opposite to the heating cycle, and the high-temperature and high-pressure gas refrigerant of the compressor 35 flows into the outdoor heat exchanger 33. Thus, the frost formation of the outdoor heat exchanger 33 was melted. In contrast, in the air conditioner 1 of FIG. 6, the high-temperature and high-pressure of the compressor 35 is opened by opening the bypass opening / closing valve (opening / closing mechanism) 49 of the hot gas bypass pipe 48 while the four-way switching valve 37 is in the heating cycle state. The state gas refrigerant is supplied to the outdoor heat exchanger 33. Thereby, the frost formation of the outdoor heat exchanger 33 is melted.

  At this time, the hot gas bypass pipe 48 supplies the high-temperature and high-pressure gas refrigerant to the outdoor heat exchanger 33 so that the temperature of the molten water becomes equal to or higher than the melting point temperature of water. This high-temperature molten water hangs down on the surface of the heat transfer fin of the outdoor heat exchanger 33 and is dropped on the drain pan 50. When the melted water (drain water) of the drain pan 50 has been frozen again, it is melted by the high-temperature melted water dripped onto the drain pan 50 and drained outside the outdoor unit 3. Thereby, since the ice column of the drain pan 50 does not grow, destruction of the outdoor heat exchanger 33 and the outdoor unit fan is not caused.

At this time, since the refrigeration cycle is not changed to the defrost cycle, the indoor heat exchanger 23 is supplied with a high-temperature and high-pressure gas refrigerant. For this reason, although a heating capability is falling, cold wind is not output.
If the supply of the high-temperature and high-pressure refrigerant from the hot gas bypass pipe 48 to the outdoor heat exchanger 33 is performed in an operation in a state where the room temperature is maintained after the room temperature reaches the set value, the heating capacity is reduced. Will not be a problem.

Also in the air conditioner 1 of the present embodiment, the hot gas pipe 45 is disposed below the outdoor heat exchanger 33. Therefore, in the heating cycle, the defrosted molten water is cooled by the refrigerant on the input side of the decompressor 34. Refreezing is prevented. Therefore, as in the control flow described with reference to FIG. 3, when the room temperature reaches the air conditioning set temperature, the outdoor heat exchange from the hot gas bypass pipe 48 is performed under extremely low temperature conditions where the outside air temperature is equal to or lower than the predetermined temperature. The high-temperature and high-pressure refrigerant is supplied to the vessel 33.
As a result, the heating cycle can be operated even in a cryogenic environment.

  In the configuration diagram of the refrigeration cycle of FIGS. 2, 5 and 6, an example in which the hot gas bypass pipe 48 branches from the middle of the discharge pipe 42 connecting the compressor 35 and the four-way switching valve 37 is shown. The inlet of the bypass pipe 48 is not limited to this place and may be another place as long as the high-temperature and high-pressure gas refrigerant discharged from the compressor 35 can be obtained. For example, you may branch from between the service valve (not shown) of the four-way switching valve 37 and the use side gas pipe 43.

Example 4
Next, the configuration of the refrigeration cycle of the air conditioner 1 having a reheat dehumidifying function will be described with reference to FIG. This reheat dehumidification function is an operation mode in which the humidity is reduced by reheating the conditioned air while removing moisture.
The air conditioner 1 of FIG. 7 implement | achieves the reheat dehumidification function by changing the structure of the indoor unit 2 of the air conditioner 1 of FIG.

Next, the configuration of the indoor unit 2 will be described.
The indoor unit 2 of FIG. 7 has two heat exchangers, a first indoor heat exchanger 23a and a second indoor heat exchanger 23b, and opens the indoor electromagnetic on-off valve 51 during heating or cooling operation, The heat exchanger 23a and the second indoor heat exchanger 23b are connected in parallel to constitute one heat exchanger (corresponding to the indoor heat exchanger 23 in FIG. 5).
In this state, the same operation as the heating operation or cooling operation described in FIG. 5 is performed.

  In the reheat dehumidifying operation, the indoor electromagnetic on-off valve 51 is closed, and the first indoor heat exchanger 23a and the second indoor heat exchanger 23b are connected in series. The gas-liquid two-phase refrigerant in the liquid pipe 44 flows through the second indoor heat exchanger 23b, is decompressed by the indoor expansion valve 52, and the refrigerant flows into the first indoor heat exchanger 23a. The refrigerant that has flowed through the first indoor heat exchanger 23 a flows through the use-side gas pipe 43 and returns to the outdoor unit 3.

  At this time, the gas-liquid two-phase refrigerant in the liquid pipe 44 is an intermediate-temperature / medium-pressure refrigerant by reducing the amount of decompression of the expansion valve 34a during the cooling operation. This medium temperature / intermediate pressure refrigerant is liquefied by flowing through the second indoor heat exchanger 23b acting as a condenser. The liquefied refrigerant is decompressed by the indoor expansion valve 52 to become a low-temperature and low-pressure refrigerant, flows through the first indoor heat exchanger 23a acting as an evaporator, and returns to the gas refrigerant.

In the first indoor heat exchanger 23a that is ventilated by the indoor fan 21 and acts as an evaporator, the indoor air is deprived of heat of vaporization, cooled and dehumidified, and in the second indoor heat exchanger 23b that acts as a condenser. It is warmed by the heat of condensation.
As described above, dehumidification is possible even with low-temperature and high-humidity air.

As described above, during the reheat dehumidifying operation, the refrigeration cycle is configured by using the first indoor heat exchanger 23a of the indoor unit 2 as an evaporator and the second indoor heat exchanger 23b as a condenser. For this reason, a refrigerating cycle can be comprised, without performing refrigerant | coolant condensation by the outdoor heat exchanger 33. FIG.
In this case, the controller 10 closes the decompressor 34 to stop the flow of the high-temperature and high-pressure gas refrigerant in the outdoor heat exchanger 33, and opens the bypass on-off valve 49 to supply the high-temperature and high-pressure gas refrigerant to the liquid pipe. 44.
At this time, the refrigerant supplied to the liquid pipe 44 is adjusted to a medium-temperature / medium-pressure gas refrigerant by controlling the compressor 35 in accordance with the amount of heat to be reheated. Or you may adjust the pressure reduction amount of the expansion valve 34a.

  The present invention is not limited to the above-described embodiments, and includes various modifications. The above-described embodiments have been described in detail for easy understanding in the present invention, and are not necessarily limited to those having all the configurations described.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Indoor unit 3 Outdoor unit 10 Control part 11 Indoor unit refrigerant | coolant temperature detection sensor 12 Outdoor unit refrigerant | coolant temperature detection sensor 13 Outdoor temperature detection sensor 14 Room temperature detection sensor 21 Indoor fan 22 Indoor air blower motor 23 Indoor heat exchanger 31 Outdoor Fan 32 Outdoor fan motor 33 Outdoor heat exchanger 34 Pressure reducer (expansion mechanism)
34a Pressure reducer (expansion mechanism or first expansion mechanism)
35 Compressor 36 Accumulator 37 Four-way selector valve 41 Suction pipe 42 Discharge pipe 43 Use side gas pipe 44 Liquid pipe 45 Hot gas pipe 46 Heat source side liquid pipe 47 Heat source side gas pipe 48 Hot gas bypass pipe 49 Bypass opening / closing valve 51 Indoor electromagnetic opening / closing Valve 52 Indoor expansion valve (second expansion mechanism)
23a 1st indoor heat exchanger 23b 2nd indoor heat exchanger

Claims (10)

A refrigerant flow path connecting a compressor, a four-way switching valve, an indoor heat exchanger, an expansion mechanism, and an outdoor heat exchanger;
The refrigerant flow path between the compressor and the four-way switching valve, the refrigerant flow path between the indoor heat exchanger and the expansion mechanism, or the expansion mechanism and the outdoor heat exchanger. A hot gas bypass pipe connecting the refrigerant flow path,
The air conditioner characterized in that the refrigerant flow path has a hot gas pipe connected between the indoor heat exchanger and the expansion mechanism and positioned below the outdoor heat exchanger. In the air conditioner according to claim 1,
An opening and closing mechanism disposed in the hot gas bypass pipe;
A controller for controlling opening and closing of the opening and closing mechanism,
The air conditioner is characterized in that the controller opens the opening / closing mechanism during a heating operation for maintaining the room temperature at a set temperature. In the air conditioner according to claim 1,
An opening and closing mechanism disposed in the hot gas bypass pipe;
A controller for controlling opening and closing of the opening and closing mechanism,
The said control part opens the said opening-closing mechanism when performing the thermo-off which stops the said compressor during an air-conditioning driving | operation, The air conditioner characterized by the above-mentioned. In the air conditioner according to claim 2 or 3,
The control unit opens the opening / closing mechanism when the outside air temperature is lower than a predetermined value. In the air conditioner according to any one of claims 1 to 4,
The air conditioner, wherein the hot gas pipe is a refrigerant pipe vertically below the outdoor heat exchanger. In the air conditioner according to claim 2 or 3,
The diameter of the hot gas bypass pipe is a use side gas pipe which is a refrigerant flow path connecting the four-way switching valve and the indoor heat exchanger, or a refrigerant flow path connecting the indoor heat exchanger and the expansion mechanism. An air conditioner characterized by having a diameter equal to or less than the diameter of the liquid pipe. In the air conditioner according to claim 1,
The air conditioner, wherein the hot gas bypass pipe is connected from above to a liquid pipe that is a refrigerant flow path connecting the indoor heat exchanger and the expansion mechanism. In the air conditioner according to claim 1,
The air conditioner characterized in that the hot gas bypass pipe has an open / close mechanism that generates a pressure loss within a predetermined value times a pressure loss of a refrigerant flow path connecting the indoor heat exchanger. In the air conditioner according to claim 1,
The hot gas bypass pipe is, instead of the refrigerant flow path between the compressor and the four-way switching valve, a refrigerant flow path connecting the four-way switching valve, the four-way switching valve, and the indoor heat exchanger. An air conditioner branched from a service valve provided on a certain use side gas pipe. A compressor, a four-way switching valve, an indoor heat exchanger, an outdoor heat exchanger, a first expansion mechanism disposed on the outdoor heat exchanger side and operating during a heating cycle, and disposed on the indoor heat exchanger side A refrigerant flow path connecting a second expansion mechanism that operates during a cooling cycle;
A refrigerant flow path connecting between the first expansion mechanism and the second expansion mechanism, a hot gas pipe positioned below the outdoor heat exchanger;
A hot gas bypass pipe connected between the refrigerant flow path between the compressor and the four-way switching valve and the second expansion mechanism side of the hot gas pipe;
Have
The indoor heat exchanger is composed of a first indoor heat exchanger and a second indoor heat exchanger,
When performing the reheat dehumidifying operation, the first indoor heat exchanger is connected in series as an evaporator, and the second indoor heat exchanger is connected as a condenser, and the second indoor heat exchange is performed from the hot gas bypass pipe. An air conditioner characterized by supplying high-temperature and high-pressure gas refrigerant to the chamber.

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