JPWO2013073070A1 - Refrigeration cycle equipment - Google Patents

Abstract

Bypass circuit for returning the refrigerant separated by the gas-liquid separator 5 provided between the expansion valve 4 and the second heat exchanger 6 (evaporator) to the suction side of the compressor 1 via the third heat exchanger 14. Liquid refrigerant into the bypass circuit 7 based on the temperature difference between the refrigerant temperature on the outlet side of the third heat exchanger 14 of the bypass circuit 7 and the refrigerant temperature on the inlet side of the third heat exchanger 14. The liquid refrigerant mixing prevention operation is performed to prevent this.

Description

  The present invention relates to a refrigeration cycle apparatus equipped with a gas-liquid separator that separates a two-phase refrigerant into a gas refrigerant and a liquid refrigerant.

  As a conventional refrigeration cycle device, a compressor, a condenser, a decompression device, a gas-liquid separator and an evaporator are sequentially connected, and one end is connected to the gas-liquid separator and the other end is connected to the evaporator and the compressor. There is a refrigeration cycle apparatus including a bypass circuit connected between them (see, for example, Patent Document 1). In this refrigeration cycle apparatus, the refrigerant is separated into a liquid phase state and a gas phase state by the gas-liquid separator, and the refrigerant in the gas phase state flows into the compressor by bypassing the evaporator by the bypass circuit. By allowing the refrigerant in the state to flow into the evaporator, the amount of heat exchange in the evaporator is increased, and the operation efficiency is improved.

Japanese Patent Laying-Open No. 2002-243284 (FIG. 1)

  However, in the technique of Patent Document 1, when the refrigerant operation amount is increased by increasing the compressor operating frequency, the gas-liquid separator is insufficiently separated between the gas refrigerant and the liquid refrigerant, and is originally intended to flow into the evaporator side. Liquid refrigerant may enter the bypass circuit. In this case, there has been a problem that the amount of liquid refrigerant flowing into the evaporator decreases and the performance of the refrigeration cycle apparatus decreases.

  The present invention has been made to solve the above-described problems, and in a refrigeration cycle apparatus equipped with a gas-liquid separator, prevents liquid refrigerant from entering the bypass circuit and prevents performance degradation. An object of the present invention is to provide a refrigeration cycle apparatus capable of performing the above.

  The refrigeration cycle apparatus according to the present invention comprises a compressor, a first heat exchanger that acts as a condenser, a decompression device, a gas-liquid separator, and a second heat exchanger that acts as an evaporator in order by piping. A connected main circuit, a bypass circuit for returning the refrigerant separated by the gas-liquid separator to the suction side of the compressor via the third heat exchanger, a flow rate adjusting device for adjusting a flow rate flowing through the bypass circuit, and a bypass circuit A first temperature detection device for detecting the refrigerant temperature on the outlet side of the third heat exchanger, a second temperature detection device for detecting the refrigerant temperature on the inlet side of the third heat exchanger of the bypass circuit, and a first temperature detection And a control device that performs a liquid refrigerant mixing prevention operation for preventing liquid refrigerant from mixing into the bypass circuit based on a temperature difference between the detected value of the device and the detected value of the second temperature detecting device.

  According to the present invention, based on the temperature difference between the detected value of the first temperature detecting device and the detected value of the second temperature detecting device, the liquid refrigerant mixing prevention operation is performed to prevent further mixing of the liquid refrigerant. As a result, it is possible to prevent performance degradation due to liquid refrigerant entering the bypass circuit.

It is a block diagram of the refrigerating-cycle apparatus (heating) which concerns on Embodiment 1 of this invention. It is a Mollier diagram which shows the relationship between the enthalpy and pressure in each of the refrigerating cycle apparatus carrying a gas-liquid separator, and the refrigerating cycle apparatus which is not carrying a gas-liquid separator. It is a block diagram of the refrigerating-cycle apparatus which does not mount a gas-liquid separator. It is a flowchart which shows the flow of liquid refrigerant mixing prevention control to the bypass circuit in the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 1 of the refrigerating-cycle apparatus (heating) which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 2 of the refrigerating-cycle apparatus (heating) which concerns on Embodiment 1 of this invention. It is a figure which shows the structural example of the specific heat exchanger of the modification 2 of FIG. It is a figure which shows the modification 3 of the refrigerating-cycle apparatus (heating) which concerns on Embodiment 1 of this invention. It is a block diagram of the refrigerating cycle apparatus which concerns on the refrigerating cycle apparatus (cooling) which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 1 of the refrigerating-cycle apparatus which concerns on the refrigerating-cycle apparatus (cooling) which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 3 of the refrigerating-cycle apparatus which concerns on the refrigerating-cycle apparatus (cooling) which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 2 of the refrigerating-cycle apparatus which concerns on the refrigerating-cycle apparatus (cooling) which concerns on Embodiment 1 of this invention. It is a block diagram of the refrigerating cycle apparatus which concerns on the refrigerating cycle apparatus (cooling / heating switching) which concerns on Embodiment 1 of this invention. It is a block diagram of the refrigeration cycle apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the flow of liquid refrigerant mixing prevention control to the bypass circuit in the refrigerating-cycle apparatus which concerns on Embodiment 2 of this invention. It is a block diagram of the refrigerating-cycle apparatus which concerns on Embodiment 3 of this invention. It is a flowchart which shows the flow of liquid refrigerant mixing prevention control to the bypass circuit in the refrigerating-cycle apparatus which concerns on Embodiment 3 of this invention. It is a block diagram of the refrigerating-cycle apparatus which concerns on Embodiment 4 of this invention. It is a flowchart which shows the flow of liquid refrigerant mixing prevention control to the bypass circuit in the refrigerating-cycle apparatus which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
(Overall configuration of refrigeration cycle equipment)
FIG. 1 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. In FIG. 1 and the drawings to be described later, the same reference numerals denote the same or corresponding parts, which are common throughout the entire specification. Furthermore, the forms of the constituent elements appearing in the entire specification are merely examples and are not limited to these descriptions. In the first embodiment, an air conditioner that performs indoor heating will be described as an example of a refrigeration cycle apparatus.
The refrigeration cycle apparatus according to Embodiment 1 includes at least a compressor 1, a first heat exchanger 3, an expansion valve 4 as a decompression device, a gas-liquid separator 5, and a second heat exchanger 6. These are sequentially connected by refrigerant piping, and constitute the main circuit of the refrigeration cycle circuit (refrigerant circuit). The refrigeration cycle apparatus further includes a first blower 30 that blows air to the first heat exchanger 3, a second blower 60 that blows air to the second heat exchanger 6, and a control device 40 that controls the entire refrigeration cycle apparatus. Yes.

  The gas-liquid separator 5 separates the gas-liquid two-phase refrigerant flowing from the expansion valve 4 into a liquid refrigerant and a gas refrigerant. In FIG. 1, the gas-liquid separator 5 is formed in a cylindrical container shape and is separated into liquid refrigerant and gas refrigerant due to the difference in gas-liquid density. Or a gas refrigerant may be used.

  The refrigeration cycle apparatus further includes a bypass circuit 7 that returns the gas refrigerant separated in the gas-liquid separator 5 to the suction side of the compressor 1. The bypass circuit 7 is provided with a third heat exchanger 14, a capillary tube 10, and an electromagnetic valve 11 that opens and closes the bypass circuit 7. Further, the bypass circuit 7 is provided with a temperature detection device 8 on the inlet side of the third heat exchanger 14 and a temperature detection device 9 on the outlet side. In addition, the connection order of the capillary tube 10 and the electromagnetic valve 11 is not limited to this, and any order may be sufficient.

  When the gas-liquid separator 5 is operated, the solenoid valve 11 is opened so that the refrigerant flows through the bypass circuit 7, and when the gas-liquid separator 5 does not need to be operated, the refrigerant is bypassed. Do not distribute to 7. Further, when the gas-liquid separator 5 is always operated, it is not necessary to close the bypass circuit 7, and therefore the electromagnetic valve 11 may be omitted.

  The capillary tube 10 is a capillary tube made of copper or the like, and adjusts the flow rate of the gaseous refrigerant to be circulated through the bypass circuit 7. An expansion valve may be used as a means for adjusting the flow rate. By using an expansion valve, the gas-liquid separator 5 can be used, for example, due to a change in the circulation amount of the refrigerant, a change in the outside air temperature or the room temperature, a change in the number of operating use side heat exchangers when there are a plurality of use side heat exchangers, etc. Even when the dryness of the two-phase refrigerant flowing into the refrigerant changes, the degree of gas refrigerant to be circulated to the bypass circuit 7 side by changing the opening of the expansion valve to make the pressure loss to the second heat exchanger 6 appropriate. You can control the amount.

  The first heat exchanger 3 and the first blower 30 are disposed in the indoor unit, and the compressor 1, the expansion valve 4, the gas-liquid separator 5, the second heat exchanger 6, the bypass circuit 7, and the third are disposed in the outdoor unit. A heat exchanger 14, a capillary tube 10 and a solenoid valve 11 are arranged.

  The control device 40 is based on detection signals from the temperature detection device 8 and the temperature detection device 9 and detection signals from other temperature detection devices and pressure detection devices (not shown). It connects so that the 1 air blower 30 and the 2nd air blower 60 can be controlled. The control device 40 further determines whether or not liquid refrigerant is mixed into the bypass circuit 7 based on the detection signals of the temperature detection device 8 and the temperature detection device 9, and controls the compressor 1 or the electromagnetic valve 11 according to the determination result. Processing is also performed. Details of this processing will be described later. In addition, the control apparatus 40 may be provided in the outdoor unit, may be provided in the indoor unit, or is configured separately into the indoor control apparatus and the outdoor control apparatus, and performs a cooperation process with each other. It may be configured.

(Heating operation of refrigeration cycle equipment)
Hereinafter, the heating operation of the refrigeration cycle apparatus will be described. It is assumed that the electromagnetic valve 11 is open.
The compressor 1 compresses the sucked gas refrigerant and discharges the high-temperature and high-pressure gas refrigerant. The refrigerant discharged from the compressor 1 flows into the first heat exchanger 3 that functions as a condenser. The first heat exchanger 3 performs heat exchange between the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 and the air sent by the first blower 30, and condenses the gas refrigerant. The refrigerant condensed in the first heat exchanger 3 flows into the expansion valve 4. The expansion valve 4 expands and decompresses the inflowing liquid refrigerant, and flows out as a low-temperature and low-pressure gas-liquid two-phase refrigerant.

  The gas-liquid two-phase refrigerant that has flowed out of the expansion valve 4 flows into the gas-liquid separator 5. The gas-liquid separator 5 separates the flowing gas-liquid two-phase refrigerant into liquid refrigerant and gas refrigerant.

  The separated liquid refrigerant flows into the second heat exchanger 6. The second heat exchanger 6 performs heat exchange between the low-temperature and low-pressure liquid refrigerant separated from the gas-liquid two-phase refrigerant by the gas-liquid separator 5 and the air sent by the second blower 60, and the low temperature The low-pressure liquid refrigerant is evaporated.

  The gas refrigerant separated from the gas-liquid two-phase refrigerant by the gas-liquid separator 5 flows into the bypass circuit 7. The gaseous refrigerant flowing into the bypass circuit 7 exchanges heat with the air from the second blower 60 in the third heat exchanger 14, passes through the capillary tube 10, and is sucked into the compressor 1.

(Gas-liquid separation operation of the gas-liquid separator 5)
FIG. 2 shows the relationship between enthalpy and pressure in each of the refrigeration cycle apparatus equipped with the gas-liquid separator and the refrigeration cycle apparatus not equipped with the gas-liquid separator 5 according to Embodiment 1 of the present invention. It is a Mollier diagram shown. FIG. 3 is a configuration diagram of a refrigeration cycle apparatus not equipped with a gas-liquid separator. In FIG. 2, the solid line indicates the relationship between the enthalpy and pressure of the refrigeration cycle apparatus equipped with the gas-liquid separator 5 and the broken line indicates the refrigeration cycle apparatus shown in FIG. Yes. Moreover, each refrigerant | coolant state which the point A-point F in FIG. 2 shows respond | corresponds to each state of the refrigerant | coolant in the point A-point F in the refrigerating-cycle apparatus which concerns on this Embodiment 1 shown by FIG. Further, the refrigerant states indicated by points A to C and D ′ in FIG. 2 correspond to the refrigerant states at points A to C and D ′ in the refrigeration cycle apparatus shown in FIG. 3.

First, the operation of the refrigeration cycle apparatus not equipped with the gas-liquid separator 5 shown in FIG. 3 will be described with reference to FIGS.
First, the high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 1 flows into the first heat exchanger 3 (point A). The gaseous refrigerant that has flowed into the first heat exchanger 3 undergoes heat exchange with room air supplied from a blower (not shown), condenses, becomes liquid refrigerant, and flows out of the first heat exchanger 3. The liquid refrigerant (point B) flowing out from the first heat exchanger 3 flows into the expansion valve 4 and is expanded and depressurized by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant (point C) flows into the second heat exchanger 6, heat exchanges with outside air supplied from a blower (not shown), evaporates, and becomes a low-temperature and low-pressure gas refrigerant. It flows out of the heat exchanger 6. The gaseous refrigerant (point D ′) flowing out from the second heat exchanger 6 flows into the compressor 1 and is compressed again.

  As described above, in the refrigeration cycle apparatus not equipped with the gas-liquid separator 5, the gas-liquid two-phase refrigerant (point C) after passing through the expansion valve 4 flows into the second heat exchanger 6, The pressure loss when the refrigerant passes through the second heat exchanger 6 increases (corresponds to (PC-PD ′) in FIG. 2).

Next, the operation of the refrigeration cycle apparatus equipped with the gas-liquid separator 5 according to the present embodiment shown in FIG. 1 will be described with reference to FIGS. 1 and 2.
First, the electromagnetic valve 11 is opened so that the refrigerant flows through the bypass circuit 7. The high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 1 flows into the first heat exchanger 3 (point A). The gaseous refrigerant that has flowed into the first heat exchanger 3 is subjected to heat exchange with room air to condense, becomes liquid refrigerant, and flows out of the first heat exchanger 3. The liquid refrigerant (point B) flowing out from the first heat exchanger 3 flows into the expansion valve 4 and is expanded and depressurized by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant (point C) flows into the gas-liquid separator 5.

  Then, the liquid refrigerant (point E) that flows out of the gas-liquid separator 5 flows into the second heat exchanger 6. The liquid refrigerant that has flowed into the second heat exchanger 6 evaporates by exchanging heat with the outside air and flows out from the second heat exchanger 6 as a gaseous refrigerant. On the other hand, the gaseous refrigerant (point F) flowing out of the gas-liquid separator 5 passes through the capillary tube 10 and the electromagnetic valve 11 in the bypass circuit 7 and then merges with the gaseous refrigerant flowing out from the second heat exchanger 6. (Point D) flows into the compressor 1 and is compressed again.

  As described above, in the refrigeration cycle apparatus equipped with the gas-liquid separator 5 according to the present embodiment shown in FIG. 1, only the liquid refrigerant passes through the second heat exchanger 6. 6 can be reduced (corresponding to (PC-PD) in FIG. 2). For this reason, the suction pressure of the compressor 1 increases from the pressure PD ′ to the pressure PD, and the amount of work required for the compressor 1 to compress from the suction pressure to the discharge pressure can be reduced. As a result, the coefficient of performance indicated by the ratio between the evaporation capacity of the second heat exchanger 6 and the input of the compressor 1 can be improved.

(Judgment of the presence or absence of liquid refrigerant in the bypass circuit 7)
In the refrigeration cycle apparatus according to the first embodiment, the third heat exchanger 14 is provided in the bypass circuit 7 so that the refrigerant flowing into the bypass circuit 7 exchanges heat with the air from the second blower 60. Then, based on the temperature of the temperature detection device 8 provided on the inlet side of the third heat exchanger 14 and the temperature of the temperature detection device 9 provided on the outlet side, the presence or absence of liquid refrigerant mixing into the bypass circuit 7 is determined. Yes. This will be specifically described below.

  When only the gas refrigerant flows into the bypass circuit 7 without mixing the liquid refrigerant, the gas refrigerant is overheated by the third heat exchanger 14, and the detected value Tin of the temperature detecting device 8 and the detected value Tout of the temperature detecting device 9 are The temperature difference increases. On the other hand, when a liquid refrigerant is mixed into the bypass circuit 7, the refrigerant changes in two phases from liquid to gas, so there is no temperature change. Further, when the amount of the liquid refrigerant mixed in the bypass circuit 7 is small, the liquid refrigerant is overheated, but the degree of overheating is smaller than that in the case of only the gas refrigerant.

  Since the state of the refrigerant flowing into the bypass circuit 7 in this way and the temperature difference between the detection value Tin of the temperature detection device 8 and the detection value Tout of the temperature detection device 9 are as described above, By detecting the temperature difference between the detection value Tin of the temperature detection device 8 and the detection value Tout of the temperature detection device 9, it can be determined whether or not liquid refrigerant is mixed in the bypass circuit 7.

  FIG. 4 is a flowchart showing a flow of liquid refrigerant mixture prevention control to the bypass circuit in the refrigeration cycle apparatus according to Embodiment 1 of the present invention. A series of processing shown in FIG. 4 is periodically performed by the control device 40. Hereinafter, the flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus of FIG. 1 will be described.

  The control device 40 detects the refrigerant temperature Tin on the inlet side of the third heat exchanger 14 with the temperature detection device 8 and detects the refrigerant temperature Tout on the outlet side of the third heat exchanger 14 with the temperature detection device 9. (S1). Then, the temperature difference Tout-Tin is compared with a preset threshold value Tset (S2). If the temperature difference Tout-Tin is less than the threshold value Tset, it is determined that liquid refrigerant is mixed, and the liquid refrigerant mixing prevention operation is performed. Perform (S3). As the liquid refrigerant mixing prevention operation, for example, the solenoid valve 11 is closed or the operation frequency of the compressor 1 is lowered to reduce the circulating refrigerant amount. If the temperature difference Tout−Tin is equal to or greater than the threshold Tset, it is determined that liquid refrigerant is not mixed, and the current operation (normal operation) is continued (S4).

(Effect of Embodiment 1)
As described above, according to the first embodiment, the liquid refrigerant that is not separated and separated by the gas-liquid separator 5 based on the refrigerant temperature difference between the inlet and the outlet of the third heat exchanger 14 provided in the bypass circuit 7. It is possible to determine whether or not there is any mixture in the bypass circuit 7.

  When it is determined that the liquid refrigerant is mixed into the bypass circuit 7, the liquid refrigerant mixing prevention operation is performed so that the liquid refrigerant is not mixed into the bypass circuit 7 any more. There is an effect that can prevent the performance degradation. Further, since the liquid refrigerant does not return to the suction side of the compressor 1, liquid compression can be prevented and the reliability of the compressor 1 can be improved.

  The refrigeration cycle apparatus may be modified as follows in addition to the configuration shown in FIG. In this case, the same effect can be obtained.

(Modification 1)
As shown in FIG. 5, an accumulator 13 may be provided on the suction side of the compressor 1.

(Modification 2)
The third heat exchanger 14 may be integrated with the first heat exchanger 3 or the second heat exchanger 6. FIG. 6 shows an example in which the third heat exchanger 14 is integrated with the second heat exchanger 6. Further, FIG. 7 shows a specific configuration example of a specific heat exchanger configured integrally as described above.

FIG. 7 is a diagram illustrating a configuration example of a heat exchanger in which the third heat exchanger is integrated with the first heat exchanger or the second heat exchanger.
In this example, the heat exchanger is composed of the heat transfer tubes 20 and the aluminum fins 21, and among the ten heat transfer tubes 20, the first heat exchanger 3 or the second heat exchanger 6 is composed of eight heat transfer tubes, and is bypassed. The circuit 7 is composed of two heat transfer tubes and constitutes a part of the third heat exchanger 14. Further, a temperature detection device 8 and a temperature detection device 9 are provided on the inlet side and the outlet side of the third heat exchanger 14 of the bypass circuit 7, respectively. In this modification 2, since the 3rd heat exchanger 14 was comprised with the heat exchanger integral with the 1st heat exchanger 3 or the 2nd heat exchanger 6, cost can be aimed at rather than manufacturing a heat exchanger separately. . In addition, although the bypass circuit 7 is arrange | positioned at the edge part of the heat exchanger in this example, the arrangement place is not restricted to an edge part.

(Modification 3)
In FIG. 1, the gas-liquid separator 5 and the third heat exchanger 14 are provided on the outdoor unit side, but may be provided on the indoor unit side as shown in FIG.

(Modification 4)
It is good also as a structure which combined suitably the modifications 1-3. For example, the modification 1 and the modification 2 may be combined, and the second heat exchanger 6 and the third heat exchanger 14 may be integrally configured in the configuration illustrated in FIG. For example, the modification 2 and the modification 3 may be combined, and the first heat exchanger 3 and the third heat exchanger 14 may be integrated in the structure illustrated in FIG. In addition, since the 1st heat exchanger 3 acts as a condenser and the 3rd heat exchanger 14 acts as an evaporator, when these are integrally formed, it will receive the influence of a mutual heat, but the influence is not so big. Therefore, there is no problem even if it is integrally formed. However, when it is configured as a single unit, a configuration in which both are evaporators as shown in FIG. 6 is preferable.

  The above modifications are similarly applied to the refrigeration cycle apparatus described below unless otherwise specified as not applicable.

  In the first embodiment, the refrigeration cycle apparatus is an air conditioner that performs heating operation, and liquid refrigerant that is not separated and partitioned by the gas-liquid separator 5 during the heating operation passes through the bypass circuit 7. An air conditioner that can prevent performance degradation has been described. However, the refrigeration cycle apparatus is not limited to an air conditioner that performs a heating operation, but may be an air conditioner that performs a cooling operation, and may be an air conditioner that can prevent a decrease in performance of the refrigeration cycle during the cooling operation. Next, FIG. 9 to FIG. 12 show an air conditioner that performs a cooling operation.

(Air conditioner that only performs cooling operation)
The difference between the air conditioner shown in FIGS. 9 to 12 and the air conditioner that performs the heating operation described so far is that the first heat exchanger 3 is a condenser and the second heat exchanger 6 is an evaporator. Instead of this, the first heat exchanger 3 is an evaporator and the second heat exchanger 6 is a condenser, and the others are the same. Hereinafter, the cooling operation will be described with reference to FIG.

(Cooling operation of refrigeration cycle equipment)
The compressor 1 compresses the sucked gas refrigerant and discharges the high-temperature and high-pressure gas refrigerant. The gaseous refrigerant discharged from the compressor 1 flows into the second heat exchanger 6, performs heat exchange with the outside air sent by the second blower 60, and condenses the gaseous refrigerant. The refrigerant condensed in the second heat exchanger 6 is expanded and decompressed by the expansion valve 4, and flows out as a low-temperature and low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flowing out from the expansion valve 4 is separated into a liquid refrigerant and a gas refrigerant by the gas-liquid separator 5.

  The separated low-temperature and low-pressure liquid refrigerant flows into the first heat exchanger 3, performs heat exchange with the indoor air sent by the first blower 30, and evaporates the low-temperature and low-pressure liquid refrigerant. On the other hand, the gas refrigerant separated by the gas-liquid separator 5 flows into the bypass circuit 7, passes through the third heat exchanger 14, the capillary tube 10 and the electromagnetic valve 11, and then passes through the first heat exchanger 3. The gas refrigerant joins and is sucked into the compressor 1. Note that the solenoid valve 11 is closed when the gas-liquid separator 5 does not need to be actuated, and the refrigerant is prevented from flowing through the bypass circuit 7 in the same manner as described above.

  Also in such a cooling operation, whether or not liquid refrigerant is mixed into the bypass circuit 7 can be determined based on the refrigerant temperature difference between the inlet side and the outlet side of the third heat exchanger 14 as in the case of the heating operation. That is, it is possible to obtain an air conditioner that can prevent the performance deterioration of the cooling operation due to the liquid refrigerant not separated and partitioned by the gas-liquid separator 5 through the bypass circuit 7 during the cooling operation.

  Here, the configuration examples of FIGS. 10 to 12 will be briefly described. FIG. 10 corresponds to Modification 1 described above (Modification 1 described in the description of the air conditioner that performs heating operation), and an accumulator 13 is provided in the configuration of FIG. 9. FIG. 11 similarly corresponds to the above-described modification example 3, in which the gas-liquid separator 5 and the third heat exchanger 14 are provided on the indoor unit side. FIG. 12 similarly corresponds to the above-described modified example 2, and the third heat exchanger 14 is integrated with the first heat exchanger 3. Although the third heat exchanger 14 may be integrated with the second heat exchanger 6, the second heat exchanger 6 is a condenser, so that the third heat exchanger 14 is replaced with the first heat exchanger 3 or the second heat exchanger 6. In integrating with the heat exchanger of either of the two heat exchangers 6, as described above, it is preferable to integrate with the first heat exchanger 3 that is an evaporator as with the third heat exchanger. Similarly, as in the above-described modification 4, each of the modifications 1 to 3 may be appropriately combined. Even if it is set as these structures, the effect similar to the above can be acquired.

(Air conditioner that can be switched between cooling operation and heating operation)
In the above description, the case where the refrigeration cycle apparatus is an air conditioner that performs heating operation or cooling operation has been described as an example. However, as shown in FIG. 13, the flow of the refrigerant discharged from the compressor 1 with the four-way valve 2 provided It is good also as an apparatus which can change a path | route and can switch between air_conditionaing | cooling operation and heating operation. In the configuration of FIG. 13A, the configuration in which the gas-liquid separator 5 is activated during the heating operation is shown. However, as illustrated in FIG. 13B, the configuration of operating the gas-liquid separator 5 in the cooling operation is illustrated. Of course it is good. When the four-way valve 2 is provided, a check valve 12 is also provided in the bypass circuit 7.

  The check valve 12 causes the refrigerant to flow only in one direction in the bypass circuit 7. Specifically, when the refrigerant discharged from the compressor 1 flows in the direction indicated by the solid line in FIG. 13 of the four-way valve 2 (heating operation), the refrigerant flows in the direction from the gas-liquid separator 5 to the compressor 1. Let Further, when the refrigerant discharged from the compressor 1 flows in the direction indicated by the broken line in FIG. 13 of the four-way valve 2 (cooling operation), the high-temperature and high-pressure gaseous refrigerant from the compressor 1 flows into the bypass circuit 7. The high-temperature and high-pressure gaseous refrigerant is all guided to the second heat exchanger 6.

  Note that the check valve 12 may be omitted because the refrigerant flow can be controlled only by opening and closing the solenoid valve 11 if the solenoid valve 11 is of a type that can be closed in both the forward and reverse directions with respect to the refrigerant flow. Further, when the gas-liquid separator 5 is always operated when the second heat exchanger 6 is operated as an evaporator, it is not necessary to close the bypass circuit 7, so the electromagnetic valve 11 may be omitted.

(Heating operation)
During the heating operation, the four-way valve 2 is switched to the solid line side. The high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 1 flows into the first heat exchanger 3 via the four-way valve 2. The subsequent operation is the same as the operation described in FIG.

(Cooling operation)
During the cooling operation, the four-way valve 2 is switched to the broken line side. Further, the solenoid valve 11 is closed to prevent the refrigerant from flowing through the bypass circuit 7.
The high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 1 flows into the second heat exchanger 6 via the four-way valve 2. The gaseous refrigerant that has flowed into the second heat exchanger 6 undergoes heat exchange with the outside air, condenses, becomes liquid refrigerant, and flows out of the second heat exchanger 6.

  The liquid refrigerant flowing out from the second heat exchanger 6 flows into the gas-liquid separator 5. The liquid refrigerant that has flowed into the gas-liquid separator 5 flows out in a liquid state. The liquid refrigerant that has flowed out of the gas-liquid separator 5 flows into the expansion valve 4 and is expanded and depressurized by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant flows into the first heat exchanger 3. The gas-liquid two-phase refrigerant that has flowed into the first heat exchanger 3 undergoes heat exchange with room air, evaporates, becomes a gaseous refrigerant, and flows out of the first heat exchanger 3. The gaseous refrigerant that has flowed out of the first heat exchanger 3 flows into the compressor 1 via the four-way valve 2 and is compressed again.

  Here, an example is shown in which the four-way valve 2 is provided in the configuration of FIG. 13 so that the heating operation and the cooling operation can be switched. However, the installation of the four-way valve 2 is not limited to the configuration of FIG. In the configuration example (including the modification), the four-way valve 2 can be provided.

Embodiment 2. FIG.
In the first embodiment, the presence or absence of liquid refrigerant in the bypass circuit 7 is determined using the temperature detection device 8 and the temperature detection device 9, but in the second embodiment, the third heat exchanger 14 The temperature detector 8 on the inlet side is omitted, and the presence or absence of liquid refrigerant in the bypass circuit 7 is determined based on the detected value of the temperature detector 9 on the outlet side of the third heat exchanger 14. . The second embodiment is different from the first embodiment in the configuration and the determination method related to the determination of the presence or absence of liquid refrigerant in the bypass circuit 7, and is otherwise the same as the first embodiment.

FIG. 14 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 2 of the present invention.
As shown in FIG. 14, the refrigeration cycle apparatus of the second embodiment has a configuration in which the temperature detection device 8 on the inlet side of the third heat exchanger 14 is omitted, and the rest is the same as that of the first embodiment shown in FIG. It is the same. When only the temperature detection device 9 is provided on the outlet side of the third heat exchanger 14 as described above, for example, the temperature detection device 9 is a temperature sensing cylinder, and a diaphragm type expansion valve 4 or the like is connected to the temperature sensing cylinder. The expansion valve 4 may be used in place of the electromagnetic valve 11. In addition, although the structural example of the refrigerating-cycle apparatus which performs heating operation was shown in FIG. 14, Embodiment 2 is applicable also to all the structures (including a modification) demonstrated in Embodiment 1. FIG.

  FIG. 15 is a flowchart showing a flow of liquid refrigerant mixture prevention control to the bypass circuit in the refrigeration cycle apparatus according to Embodiment 2 of the present invention. A series of processing shown in FIG. 15 is periodically performed by the control device 40. Hereinafter, the flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus of FIG. 14 will be described.

  The control device 40 detects the refrigerant temperature Tout on the outlet side of the third heat exchanger 14 by the temperature detection device 9 (S11). The control device 40 obtains and stores in advance a correlation between the presence or absence of liquid refrigerant in the bypass circuit 7 and the detection value of the temperature detection device 9 by a test or the like, and the correlation and the detection value Tout of the temperature detection device 9 From this, it is determined whether or not liquid refrigerant is mixed (S12). The subsequent processing is the same as that of the first embodiment shown in FIG. 5. When it is determined that liquid refrigerant is mixed, liquid refrigerant mixing prevention operation is performed (S13). The operation (normal operation) is continued (S14).

  As described above, according to the second embodiment, the same effects as those of the first embodiment can be obtained, and the presence / absence of liquid refrigerant in the bypass circuit 7 is determined only by the detection value of the temperature detection device 9. be able to.

Embodiment 3 FIG.
In the third embodiment, whether or not liquid refrigerant is mixed into the bypass circuit 7 different from those in the first and second embodiments is determined. The third embodiment is different from the first embodiment in the configuration and the determination method related to the determination of the presence or absence of liquid refrigerant in the bypass circuit 7, and is otherwise the same as the first embodiment.

FIG. 16 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 3 of the present invention.
The refrigeration cycle apparatus of Embodiment 3 omits the temperature detection device 8 provided on the inlet side of the third heat exchanger 14 in the configuration of Embodiment 1, and has the same equipment as the third heat exchanger 14 (here Then, the temperature detection device 9A is provided on the outlet side of the second heat exchanger 6 disposed in the outdoor unit.

  FIG. 17 is a flowchart showing a flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus according to Embodiment 3 of the present invention. A series of processing shown in FIG. 17 is periodically performed by the control device 40. Hereinafter, the flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus of FIG. 16 will be described.

  The control device 40 detects the refrigerant temperature Tout-3 on the outlet side of the third heat exchanger 14 by using the temperature detection device 9, and the refrigerant temperature Tout-2 on the outlet side of the second heat exchanger 6 by using the temperature detection device 9A. Is detected (S21). The control device 40 compares the refrigerant temperature Tout-3 with the refrigerant temperature Tout-2 (S22). If the refrigerant temperature Tout-3 is equal to or lower than the refrigerant temperature Tout-2, it is determined that liquid refrigerant is mixed, and the control is performed. The liquid refrigerant mixing prevention operation is performed in the same manner as in the first embodiment (S23), and when the refrigerant temperature Tout-3 is higher than the refrigerant temperature Tout-2, it is determined that liquid refrigerant is not mixed, and the current operation (normal operation) is continued. (S24). Note that the control device 40 obtains and stores a correlation between the presence / absence of liquid refrigerant in the bypass circuit 7 and the comparison value of the refrigerant temperature Tout-3 and the refrigerant temperature Tout-2 in advance by a test or the like, and stores the correlation and the refrigerant temperature Tout. -3 and refrigerant temperature Tout-2 may be used to determine whether liquid refrigerant is mixed.

  As described above, according to the third embodiment, the same effect as that of the first embodiment can be obtained, and the determination of the presence or absence of liquid refrigerant in the bypass circuit 7 can be performed by the temperature detection device 9 and the temperature detection device 9A. It can be judged from the detected value. In addition, although the structural example of the refrigerating-cycle apparatus which performs heating operation was shown in FIG. 16, Embodiment 3 is 3rd heat exchange among all the structural examples (including modification) demonstrated in Embodiment 1. FIG. This is applicable when the heat exchanger (the first heat exchanger 3 or the second heat exchanger 6) disposed in the same apparatus together with the evaporator is an evaporator. Specifically, in the examples shown so far, the present invention can be applied to configurations other than those shown in FIGS. In the configurations of FIGS. 8, 9, and 10, the heat exchanger disposed in the same apparatus together with the third heat exchanger functions as a condenser. Therefore, the refrigerant temperature at the outlet of the condenser and the third as the evaporator. The comparison with the refrigerant temperature at the outlet of the heat exchanger cannot determine whether liquid has entered the bypass circuit 7. Therefore, these are not applicable, but can be applied to other cases.

Embodiment 4 FIG.
In the fourth embodiment, whether or not liquid refrigerant is mixed into the bypass circuit 7 different from those in the first to third embodiments is determined. The fourth embodiment is different from the first embodiment in the configuration and the determination method related to the determination of the presence or absence of liquid refrigerant in the bypass circuit 7, and is otherwise the same as the first embodiment.

FIG. 18 is a configuration diagram of a refrigeration cycle apparatus according to Embodiment 4 of the present invention.
The refrigeration cycle apparatus of the fourth embodiment omits the temperature detection device 8 provided on the inlet side of the third heat exchanger 14 and the temperature detection device 9 provided on the outlet side in the configuration of the first embodiment, The room temperature detecting device 9B for detecting the room temperature is provided in the indoor unit.

  FIG. 19 is a flowchart showing a flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus according to Embodiment 4 of the present invention. A series of processing shown in FIG. 19 is periodically performed by the control device 40. Hereinafter, the flow of liquid refrigerant mixture prevention control to the bypass circuit 7 in the refrigeration cycle apparatus of FIG. 18 will be described.

  The controller 40 monitors the change in the room temperature by the room temperature detector 9B (S31), and checks whether the room temperature does not change for a predetermined time (for example, 10 minutes) or more (S32). When the room temperature changes during the predetermined time, the control device 40 determines that liquid refrigerant is mixed, and performs the liquid refrigerant mixing prevention operation as in the first embodiment (S33). In the refrigeration cycle apparatus, control is performed so that the room temperature detected by the room temperature detection device 9B maintains the set temperature. If liquid refrigerant is mixed, the performance of the refrigeration cycle apparatus is degraded, so the set temperature can be maintained. Disappear. That is, the room temperature decreases during heating operation. Therefore, mixing of the liquid refrigerant can be detected by detecting this temperature drop. On the other hand, if the room temperature has not changed for a predetermined time or longer, the control device 40 determines that no liquid refrigerant is mixed and continues the current operation (normal operation) (S34).

  As described above, according to the fourth embodiment, the same effect as in the first embodiment can be obtained, and the determination of the presence or absence of liquid refrigerant in the bypass circuit 7 can be determined from the detection value of the room temperature detection device 9B. . In addition, although the structural example of the refrigerating cycle apparatus which performs heating operation was shown in FIG. 18, Embodiment 4 is applicable to all the structural examples (including a modification) demonstrated in Embodiment 1. FIG.

  In addition, it does not specifically limit as a refrigerant | coolant which circulates the refrigerating-cycle apparatus based on the said Embodiment 1-4, However, Carbon dioxide or hydrocarbon which is natural refrigerant | coolants other than CFC-type refrigerant | coolants, such as R410A, R32, or R161 Etc. can be used. In addition, you may use as a refrigerant | coolant which uses the tetrafluoro propene which is a refrigerant | coolant with a low global warming potential as a component.

  In the first to fourth embodiments, the bypass circuit 7 that connects the suction side of the compressor 1 from the gas-liquid separator 5 includes the electromagnetic valve 11, the check valve 12, and the capillary tube 10. It is not limited to this, It is good also as a structure provided with a flow regulating valve instead of these.

  Moreover, although the air conditioner was demonstrated to the example as a refrigerating cycle apparatus which concerns on the said Embodiment 1-4, it is not limited to this, It applies to other refrigerating cycle apparatuses, such as a heat pump type hot water supply apparatus or a refrigerator. It is good as a thing. Furthermore, although the gas-liquid separator 5 which concerns on the said Embodiment 1-4 shall be mounted in a refrigerating-cycle apparatus, it is not limited to this, It applies to the gas-liquid separation of other fluids instead of a refrigerant | coolant It is good to do.

  DESCRIPTION OF SYMBOLS 1 Compressor, 2 Four way valve, 3 1st heat exchanger, 4 Expansion valve, 5 Gas-liquid separator, 6 2nd heat exchanger, 7 Bypass circuit, 8 Temperature detection apparatus, 9 Temperature detection apparatus, 9A Temperature detection apparatus , 9B Room temperature detection device, 10 Capillary tube, 11 Solenoid valve, 12 Check valve, 13 Accumulator, 14 Third heat exchanger, 20 Heat transfer tube, 21 Aluminum fin, 30 First blower, 40 Control device, 60 Second blower .

Claims (18)

A main circuit in which a compressor, a first heat exchanger that acts as a condenser, a decompression device, a gas-liquid separator, and a second heat exchanger that acts as an evaporator are sequentially connected by piping;
A bypass circuit for returning the refrigerant separated by the gas-liquid separator to the suction side of the compressor via a third heat exchanger;
A flow rate adjusting device for adjusting a flow rate flowing through the bypass circuit;
A first temperature detection device for detecting a refrigerant temperature on the outlet side of the third heat exchanger of the bypass circuit;
A second temperature detection device for detecting a refrigerant temperature on the inlet side of the third heat exchanger of the bypass circuit;
A control device that performs a liquid refrigerant mixing prevention operation for preventing liquid refrigerant from being mixed into the bypass circuit based on a temperature difference between a detection value of the first temperature detection device and a detection value of the second temperature detection device; A refrigeration cycle apparatus comprising:   The control device determines whether liquid refrigerant is mixed into the bypass circuit from the gas-liquid separator based on a temperature difference between a detection value of the first temperature detection device and a detection value of the second temperature detection device. 2. The refrigeration cycle apparatus according to claim 1, wherein when it is determined that liquid refrigerant is mixed, the liquid refrigerant mixing prevention operation is performed.   When the temperature difference between the detection value of the first temperature detection device and the detection value of the second temperature detection device is less than a threshold value, the control device includes liquid refrigerant, and when the temperature difference is greater than or equal to the threshold value, The refrigeration cycle apparatus according to claim 2, wherein it is determined that liquid refrigerant is not mixed. A main circuit in which a compressor, a first heat exchanger that acts as a condenser, a decompression device, a gas-liquid separator, and a second heat exchanger that acts as an evaporator are sequentially connected by piping;
A bypass circuit for returning the refrigerant separated by the gas-liquid separator to the suction side of the compressor via a third heat exchanger;
A flow rate adjusting device for adjusting a flow rate flowing through the bypass circuit;
A first temperature detection device for detecting a refrigerant temperature on the outlet side of the third heat exchanger of the bypass circuit;
A refrigeration cycle apparatus comprising: a control device that performs a liquid refrigerant mixture prevention operation for preventing liquid refrigerant from mixing into the bypass circuit based on a detection value of the first temperature detection device.   The control device determines whether or not liquid refrigerant is mixed into the bypass circuit from the gas-liquid separator based on the detection value of the first temperature detection device. The refrigeration cycle apparatus according to claim 4, wherein the refrigeration cycle apparatus is operated.   The control device obtains and stores in advance a correlation between the presence or absence of liquid refrigerant in the bypass circuit and the detected value of the first temperature detecting device, and the detected value and the correlation of the first temperature detecting device are stored. 6. The refrigeration cycle apparatus according to claim 5, wherein presence or absence of liquid refrigerant is determined based on the determination. A main circuit in which a compressor, a first heat exchanger that acts as a condenser, a decompression device, a gas-liquid separator, and a second heat exchanger that acts as an evaporator are sequentially connected by piping;
A bypass circuit for returning the refrigerant separated by the gas-liquid separator to the suction side of the compressor via a third heat exchanger;
A flow rate adjusting device for adjusting a flow rate flowing through the bypass circuit;
A first temperature detection device for detecting a refrigerant temperature on the outlet side of the third heat exchanger of the bypass circuit;
A second temperature detection device for detecting the refrigerant temperature on the outlet side of the second heat exchanger;
And a control device that performs a liquid refrigerant mixture prevention operation for preventing liquid refrigerant from mixing into the bypass circuit based on the detection value of the first temperature detection device and the detection value of the second temperature detection device. A refrigeration cycle apparatus characterized by that.   The control device determines whether liquid refrigerant is mixed into the bypass circuit from the gas-liquid separator based on a temperature difference between a detection value of the first temperature detection device and a detection value of the second temperature detection device. 8. The refrigeration cycle apparatus according to claim 7, wherein when the liquid refrigerant is mixed, the liquid refrigerant mixing prevention operation is performed.   The control device compares the detection value of the first temperature detection device with the second temperature detection device, and if the detection value of the first temperature detection device is less than or equal to the detection value of the second temperature detection device, 9. The refrigeration cycle according to claim 8, wherein it is determined that the refrigerant is mixed, and if the detected value of the first temperature detecting device is higher than the detected value of the second temperature detecting device, it is determined that the liquid refrigerant is not mixed. apparatus. A main circuit in which a compressor, a first heat exchanger that acts as a condenser, a decompression device, a gas-liquid separator, and a second heat exchanger that acts as an evaporator are sequentially connected by piping;
A bypass circuit for returning the refrigerant separated by the gas-liquid separator to the suction side of the compressor via a third heat exchanger;
A flow rate adjusting device for adjusting a flow rate flowing through the bypass circuit;
A room temperature detector for detecting the temperature in the room where the first heat exchanger or the second heat exchanger is installed;
A refrigeration cycle apparatus comprising: a control device that performs a liquid refrigerant mixing operation for preventing liquid mixture into the bypass circuit based on a time change in room temperature detected by the room temperature detection device.   The controller determines whether liquid refrigerant is mixed into the bypass circuit from the gas-liquid separator based on a time change in room temperature detected by the room temperature detector, and determines that liquid refrigerant is mixed, The refrigeration cycle apparatus according to claim 10, wherein the refrigerant mixing prevention operation is performed.   The control device determines that liquid refrigerant is mixed when the room temperature changes during a predetermined time set in advance, and that liquid refrigerant is not mixed when the room temperature does not change for the predetermined time or more. The refrigeration cycle apparatus according to claim 11.   The refrigeration cycle apparatus according to any one of claims 1 to 12, wherein the second heat exchanger and the third heat exchanger are configured as an integral heat exchanger.   The said 1st heat exchanger and said 3rd heat exchanger were comprised by the integral heat exchanger, The any one of Claims 1 thru | or 6 and Claims 10 thru | or 12 characterized by the above-mentioned. Refrigeration cycle equipment.   A four-way valve for switching a circulation direction of the refrigerant in the main circuit; the first heat exchanger is switched from the condenser to the evaporator by switching the four-way valve; and the second heat exchanger is the evaporation The refrigeration cycle apparatus according to any one of claims 1 to 13, wherein the refrigeration cycle apparatus can be operated by switching from a condenser to a condenser.   The refrigeration cycle apparatus according to any one of claims 1 to 15, wherein the first heat exchanger is disposed in the indoor unit, and the second heat exchanger is disposed in the outdoor unit.   The refrigeration cycle apparatus according to any one of claims 1 to 15, wherein the second heat exchanger is disposed in the indoor unit, and the first heat exchanger is disposed in the outdoor unit.   18. The liquid refrigerant mixing prevention operation is an operation in which the flow rate adjusting device is closed or a compressor frequency is lowered to reduce a circulating refrigerant amount. The refrigeration cycle apparatus according to item.

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