WO2021240616A1

WO2021240616A1 - Refrigeration cycle device

Info

Publication number: WO2021240616A1
Application number: PCT/JP2020/020610
Authority: WO
Inventors: 真哉東井上
Original assignee: 三菱電機株式会社
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2021-12-02
Also published as: JPWO2021240616A1; JP7309064B2

Abstract

Provided is a refrigeration cycle system comprising: a refrigerant circuit which includes a compressor; a heater which is provided to an intake pipe of the compressor; two temperature sensors which are provided to the intake pipe at a part upstream of the heater and a part downstream of the heater, respectively; a warning device which outputs a warning; and a control device. The control device uses the rotation speed of the compressor to calculate the requested heating amount of the heater (step S10), and causes the heater to operate so that the amount of heating by the heater becomes the requested heating amount (step S12). The control device calculates the difference between values detected by the two temperature sensors during the operation of the heater as the sensor temperature difference ΔT (step S14). When a period (liquid floodback operation period) during which the sensor temperature difference ΔT is less than a reference value Tref has exceeded a reference period (step S22), the control device causes the warning device to output a warning (step S24).

Description

Refrigeration cycle device

The present disclosure relates to a refrigeration cycle device in which a refrigerant circulates in a circulation flow path connecting a compressor, a condenser, a decompression device, and an evaporator.

In the refrigeration cycle device, when liquid return occurs in which the amount of liquid refrigerant sucked into the compressor becomes excessive, the lubricating oil in the sliding part of the compressor is diluted, and as a result, the sliding part of the compressor is properly lubricated. It may not be done. Therefore, the liquid return can be a cause of failure of the compressor.

For example, Japanese Patent Application Laid-Open No. 62-66065 discloses a refrigerating cycle device capable of preventing liquid from returning to a compressor. In this refrigeration cycle device, an electric coil that functions as a heater is arranged in a suction flow path connected to the suction port of the compressor, and temperature sensors are arranged at both ends of the electric coil. The wetness of the refrigerant gas in the suction pipe is determined from the change in the detected value of the temperature sensor during the operation of the electric coil, and the opening of the expansion valve is adjusted according to the magnitude of the wetness of the refrigerant gas in the suction pipe. The liquid is prevented from returning to the compressor by stopping the liquid.

Japanese Unexamined Patent Publication No. 62-66065

In the above-mentioned Japanese Patent Application Laid-Open No. 62-66065, control is performed to prevent liquid return based on the result of estimating the wetness in the suction flow path from the temperature difference between both ends of the electric coil during operation of the electric coil.

However, the relationship between the temperature difference between both ends of the electric coil and the wetness in the suction flow path can change depending on the flow rate of the refrigerant in the suction flow path (the amount of refrigerant flowing per unit time). That is, even if the wetness in the suction flow path is the same, if the refrigerant flow rate in the suction flow path is different, the temperature difference between both ends of the electric coil will be different, and the wetness in the suction flow path will be different. There is a concern that the estimation accuracy will decrease. However, the above-mentioned Japanese Patent Application Laid-Open No. 62-66065 does not mention such a problem and its countermeasures.

Further, in the above-mentioned Japanese Patent Application Laid-Open No. 62-66065, since the control for preventing the liquid return is merely performed, the user does not notice that the liquid return has occurred and performs the maintenance of the refrigeration cycle device. It is not possible to take measures such as.

The present disclosure has been made to solve the above-mentioned problems, and the purpose of the present disclosure is to accurately estimate the return of liquid to the compressor and warn the user.

The refrigeration cycle system according to the present disclosure includes a refrigerant circuit including a compressor and a suction flow path connected to a suction port of the compressor, a heater provided in the suction flow path, a warning device for outputting a warning to a user, and a warning device. It is equipped with a control device that controls a heater and a warning device. The control device calculates the required heating amount using the rotation speed of the compressor, operates the heater so that the heating amount by the heater becomes the required heating amount, and is on the upstream side of the heater in the suction flow path while the heater is operating. When the temperature difference between the first portion arranged in the heater and the second portion arranged on the downstream side of the heater is less than the reference value, the warning device is made to output a warning.

According to the present disclosure, it is possible to accurately estimate the liquid return to the compressor and warn the user.

It is a figure (the 1) which shows typically an example of the whole structure of a refrigerating cycle apparatus. It is a flowchart (the 1) which shows an example of the processing procedure of a control device. It is a figure which shows an example of the correspondence relation between the rotation speed of a compressor, and the required heating amount of a heater. It is a figure which shows the correspondence relationship between the inlet dryness and a sensor temperature difference ΔT. It is a figure (the 2) which shows typically an example of the whole structure of a refrigerating cycle apparatus. It is a flowchart (the 2) which shows an example of the processing procedure of a control device.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application to appropriately combine the configurations described in the respective embodiments. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

Embodiment 1.
[Description of configuration]
FIG. 1 is a diagram schematically showing an example of the overall configuration of the refrigeration cycle apparatus 1 according to the first embodiment. The refrigeration cycle device 1 includes a refrigerant circuit RC,

temperature sensors

10 and 20, a heater 30, a power supply 40, a warning device 120, and a control device 100.

The refrigerant circuit RC circulates the refrigerant by connecting the compressor 2, the flow path switching device 3, the first heat exchanger 4, the decompression device 5, the second heat exchanger 6, and the receiver 7. It constitutes a circulation flow path. A refrigerant with a phase change such as carbon dioxide and R410A circulates inside the refrigerant circuit RC.

The compressor 2 sucks in the low pressure refrigerant, compresses it, and discharges it as the high pressure refrigerant. The compressor 2 discharges a refrigerant having a flow rate corresponding to the rotation speed. The compressor 2 is, for example, an inverter compressor having a variable rotation speed (discharge flow rate). The flow rate of the refrigerant circulating in the refrigeration cycle device 1 is controlled by adjusting the rotation speed (discharge flow rate) of the compressor 2.

The first heat exchanger 4 is a heat exchanger having a flow path through which the refrigerant flows. In the first heat exchanger 4, heat exchange is performed between the refrigerant flowing in the flow path and the air outside the flow path.

The decompression device 5 decompresses the high-pressure refrigerant. As the pressure reducing device 5, a device provided with a valve body whose opening degree can be adjusted, for example, an electronically controlled expansion valve can be used.

The second heat exchanger 6 is a heat exchanger having a flow path through which the refrigerant flows. In the second heat exchanger 6, heat exchange is performed between the refrigerant flowing in the flow path and the air outside the flow path.

The receiver 7 is a container for storing the refrigerant inside, and is installed on the suction side of the compressor 2. An suction port to which a pipe through which the refrigerant flows is connected and a discharge port to which a pipe through which the refrigerant flows out are connected are provided on the upper portion of the receiver 7. The refrigerant is gas-liquid separated in the receiver 7. The gas-liquid separated gas refrigerant is sucked into the compressor 2.

The refrigeration cycle device 1 can be operated by switching between the cooling mode and the heating mode by switching the state of the flow path switching device 3.

The flow path switching device 3 is provided on the discharge side of the compressor 2. The flow path switching device 3 is configured to switch the refrigerant discharged from the compressor 2 to either the first heat exchanger 4 or the second heat exchanger 6 and flow the refrigerant. In the flow path switching device 3, the discharge side of the compressor 2 is connected to the first heat exchanger 4, the suction side of the compressor 2 is connected to the second heat exchanger 6, and the refrigerant discharged from the compressor 2 is connected. In the "first state", the discharge side of the compressor 2 is connected to the second heat exchanger 6, and the suction side of the compressor 2 is connected to the first heat exchanger 4. , The "second state" in which the refrigerant discharged from the compressor 2 flows through the second heat exchanger 6 is selectively controlled. Note that FIG. 1 shows an example in which the flow path switching device 3 is controlled to the “first state”.

In the cooling mode, the flow path switching device 3 is set to the first state, and the discharge side of the compressor 2 is connected to the first heat exchanger 4. In the cooling mode, the first heat exchanger 4 functions as a condenser and the second heat exchanger 6 functions as an evaporator. In the cooling mode, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the first heat exchanger 4 via the flow path switching device 3. The high-temperature and high-pressure refrigerant exchanges heat with the outside air in the first heat exchanger 4, the temperature drops, and the refrigerant flows out of the first heat exchanger 4. The refrigerant flowing out of the first heat exchanger 4 is decompressed by the decompression device 5, becomes a low-temperature low-pressure refrigerant, and flows into the second heat exchanger 6. The low-temperature low-pressure refrigerant exchanges heat with the outside air in the second heat exchanger 6, the temperature rises, and the refrigerant flows out of the second heat exchanger 6. The refrigerant flowing out of the second heat exchanger 6 flows into the receiver 7 via the flow path switching device 3, and is gas-liquid separated in the receiver 7. The gas refrigerant in the receiver 7 is sucked into the compressor 2.

In the heating mode, the flow path switching device 3 is set to the second state, and the discharge side of the compressor 2 is connected to the second heat exchanger 6. In the heating mode, the first heat exchanger 4 functions as an evaporator and the second heat exchanger 6 functions as a condenser. In the heating mode, the high-temperature and high-pressure refrigerant discharged from the compressor 2 flows into the second heat exchanger 6 via the flow path switching device 3. The high-temperature and high-pressure refrigerant exchanges heat with the water flowing through the outside air in the second heat exchanger 6, the temperature drops, and the refrigerant flows out of the second heat exchanger 6. The refrigerant flowing out of the second heat exchanger 6 is decompressed by the decompression device 5, becomes a low-temperature low-pressure refrigerant, and flows into the first heat exchanger 4. The low-temperature low-pressure refrigerant exchanges heat with the outside air in the first heat exchanger 4, rises in temperature, and flows out of the first heat exchanger 4. The refrigerant flowing out of the first heat exchanger 4 flows into the receiver 7 via the flow path switching device 3, and is gas-liquid separated in the receiver 7. The gas refrigerant in the receiver 7 is sucked into the compressor 2.

The discharge port of the receiver 7 and the suction port of the compressor 2 are connected by a suction pipe (suction flow path) P1. The refrigerant discharged from the receiver 7 is sucked into the compressor 2 via the suction pipe P1.

A heater 30 is provided on the suction pipe P1. The heater 30 generates heat by the electric power supplied from the power source 40 to heat the suction pipe P1. The amount of heating by the heater 30 (the amount of electric power supplied from the power source 40 to the heater 30) is adjusted by the control device 100 controlling the power source 40.

A temperature sensor (first temperature sensor) 10 is provided in a portion of the suction pipe P1 on the upstream side of the heater 30. A second temperature sensor (second temperature sensor) 20 is provided in a portion of the suction pipe P1 on the downstream side of the heater 30. The detection results of the

temperature sensors

10 and 20 are transmitted to the control device 100.

The warning device 120 outputs a warning to the user by using a warning lamp, a display, a speaker, and the like. The content of the warning output by the warning device 120 is controlled in response to a command from the control device 100.

The control device 100 includes a CPU (Central Processing Unit), a memory, and input / output ports for inputting / outputting various signals. The control device 100 is based on each device (compressor 2, flow path switching device) of the refrigerating cycle device 1 based on signals from each sensor (for example,

temperature sensors

10, 20, etc.) and a program stored in a memory. 3. The decompression device 5, the heater 30, the warning device 120, etc.) are controlled. The control performed by the control device 100 is not limited to processing by software, but can also be processed by dedicated hardware (electronic circuit).

[Estimation of liquid return to the compressor and warning to the user]
In the refrigeration cycle device 1, a receiver 7 for gas-liquid separation of the refrigerant is provided on the upstream side of the suction pipe P1 of the compressor 2. Then, in the normal state, the gas refrigerant in the receiver 7 is sucked into the compressor 2 via the suction pipe P1.

However, for example, in a situation where the receiver 7 is fully filled with the liquid refrigerant, the liquid refrigerant flows out from the receiver 7 to the suction pipe P1, and a liquid return occurs in which the liquid refrigerant sucked into the compressor 2 becomes excessive. obtain.

When liquid return occurs, the lubricating oil in the sliding part of the compressor 2 is diluted, and as a result, the sliding part of the compressor 2 may not be properly lubricated. Therefore, the liquid return can be a cause of failure of the compressor 2. If the user does not notice that such liquid return has occurred, the user cannot take measures such as performing maintenance of the refrigerating cycle device 1.

Therefore, in the refrigerating cycle device 1 according to the first embodiment, the heater 30 and the temperature sensor 10 described above are used as devices for detecting (estimating) the liquid return to the compressor 2 and encouraging the user to perform maintenance or the like. 20 is provided in the suction pipe P1 of the compressor 2, and a warning device 120 for outputting a warning to the user is provided.

When there is no liquid refrigerant in the suction pipe P1 while the heater 30 is in operation, the heat generated by the heater 30 is transmitted to the gas refrigerant in the suction pipe P1 and the temperature on the downstream side of the heater 30 becomes higher. Temperature difference between the heater upstream part (first part) arranged on the upstream side of the heater 30 and the heater downstream part (second part) arranged on the downstream part of the heater 30 (hereinafter, "temperature difference before and after the heater"). ") Is relatively large. On the other hand, when the liquid refrigerant is present in the suction pipe P1 while the heater 30 is in operation, a part of the heat generated by the heater 30 is transferred not only to the gas refrigerant but also to the liquid refrigerant, and the larger the amount of the liquid refrigerant, the more the heater. Since the temperature rise on the downstream side of 30 is suppressed, the temperature difference before and after the heater becomes small.

In view of this point, the control device 100 according to the first embodiment has a detection value of the temperature sensor 10 provided in the upstream portion of the heater and a detection value of the temperature sensor 20 provided in the downstream portion of the heater while the heater 30 is in operation. The difference (hereinafter also referred to as “sensor temperature difference ΔT”) is calculated as the temperature difference before and after the heater described above, and when the sensor temperature difference ΔT is less than the reference value Tref, it is estimated that liquid return has occurred, and a warning device is used. Make 120 output a warning. The reference value Tref is a fixed value stored in advance in the memory of the control device 100.

Here, the temperature difference before and after the heater (sensor temperature difference ΔT) can change not only by the amount of heat generated by the heater 30 but also by the flow rate of the refrigerant in the suction pipe P1. Therefore, if the amount of heat generated by the heater 30 is set to a fixed value, the sensor temperature difference ΔT will fluctuate according to the flow rate of the refrigerant, and the liquid return estimated by comparing the sensor temperature difference ΔT with the reference value Tref (fixed value). The estimation accuracy of is reduced.

Therefore, in the control device 100 according to the present embodiment, when the heater 30 is operated to estimate the liquid return, the temperature difference before and after the heater (sensor temperature difference ΔT) does not fluctuate according to the flow rate of the refrigerant in the suction pipe P1. As described above, the amount of heat generated by the heater 30 is adjusted by using the rotation speed of the compressor 2. This makes it possible to accurately estimate the liquid return regardless of the flow rate of the refrigerant.

FIG. 2 is a flowchart showing an example of a processing procedure executed when the control device 100 estimates the liquid return and warns the user. This flowchart is repeatedly executed every time a predetermined condition is satisfied (for example, every predetermined cycle) while the compressor 2 is in operation.

First, the control device 100 calculates the required heating amount of the heater 30 using the rotation speed of the compressor 2 (step S10). As described above, this step is performed to adjust the required heating amount of the heater 30 so that the temperature difference before and after the heater (sensor temperature difference ΔT) does not fluctuate according to the flow rate of the refrigerant.

FIG. 3 is a diagram showing an example of the correspondence between the rotation speed of the compressor 2 and the required heating amount of the heater 30. As shown in FIG. 3, the higher the rotation speed of the compressor 2, the larger the required heating amount of the heater 30 is adjusted. A map defining the correspondence relationship as shown in FIG. 3 is stored in the memory of the control device 100 in advance, and the control device 100 calculates the required heating amount corresponding to the rotation speed of the compressor 2 with reference to the map. do.

Returning to FIG. 2, the control device 100 operates the heater 30 so that the heating amount by the heater 30 becomes the required heating amount calculated in step S10 (step S12).

Next, the control device 100 calculates the above-mentioned sensor temperature difference ΔT (difference between the detected value of the temperature sensor 10 and the detected value of the temperature sensor 20) as the temperature difference before and after the heater while the heater 30 is in operation (step S14).

Next, the control device 100 reads out the reference value Tref from the memory (step S16), and determines whether or not the sensor temperature difference ΔT calculated in step S14 is less than the reference value Tref (step S18). When the sensor temperature difference ΔT is not less than the reference value Tref (NO in step S18), it is presumed that the suction pipe P1 contains almost no liquid refrigerant and no liquid return occurs. The subsequent processing is skipped and the processing is moved to the return.

On the other hand, when the sensor temperature difference ΔT is less than the reference value Tref (YES in step S18), the control device 100 presumes that a large amount of liquid refrigerant is contained in the suction pipe P1 and liquid return occurs. The "liquid back operation time" is counted up (step S20). The "liquid back operation time" is an index showing the cumulative time of operation in a state where liquid return has occurred since the previous maintenance. The liquid back operation time is stored in, for example, the memory of the control device 100.

The control device 100 determines whether or not the liquid back operation time exceeds the reference time (step S22). When the liquid back operation time does not exceed the reference time (NO in step S22), the control device 100 skips the subsequent processing and shifts the processing to the return.

When the liquid back operation time exceeds the reference time (YES in step S22), the control device 100 outputs a warning indicating that the liquid back operation time exceeds the reference time to the warning device 120 (step S24). The warning output in step S24 may include content urging the user to undergo maintenance of the refrigeration cycle device 1.

Further, the history of the liquid back operation time may be maintained even after the warning in step S24 so that the manufacturer or the contractor who maintains the refrigeration cycle apparatus 1 can make a diagnosis of the refrigeration cycle apparatus 1. However, if the compressor 2 is replaced with a new one at the time of maintenance, it is desirable to reset the liquid back operation time.

As described above, the control device 100 according to the present embodiment presumes that liquid return has occurred when the sensor temperature difference ΔT during operation of the heater 30 is less than the reference value Tref, and causes the warning device 120. Output a warning. At this time, the amount of heating by the heater 30 is adjusted by using the rotation speed of the compressor 2 so that the sensor temperature difference ΔT does not fluctuate according to the flow rate of the refrigerant. This makes it possible to accurately estimate the liquid return regardless of the flow rate of the refrigerant.

Further, in the control device 100 according to the present embodiment, when the "liquid back operation time", which is the cumulative time for which the sensor temperature difference ΔT is determined to be less than the reference value Tref, exceeds the reference time, the liquid back is performed. A warning indicating that the operating time has exceeded the reference time is output to the warning device 120. The user who receives this warning can avoid a sudden failure of the compressor 2 by taking measures such as inspecting the refrigerating cycle device 1 and performing maintenance at an early stage.

Modification example 1.
In the above-described first embodiment, in determining whether or not the temperature difference before and after the heater is less than the reference value Tref, the sensor temperature difference ΔT is calculated as the temperature difference before and after the heater, and the sensor temperature difference ΔT is defined as the reference value Tref. I'm comparing. However, the method for determining whether or not the temperature difference before and after the heater is less than the reference value Tref is not limited to this method.

FIG. 4 is a diagram showing the correspondence between the dryness (inlet dryness) of the inlet portion of the heater 30 in the suction pipe P1 and the temperature difference before and after the heater (sensor temperature difference ΔT). As can be understood from FIG. 4, the fact that the inlet dryness is less than the threshold value xin is equivalent to the fact that the temperature difference before and after the heater (sensor temperature difference ΔT) is less than the reference value Tref. In view of this point, for example, the inlet enthalpy of the heater upstream portion is calculated as the inlet dryness from the temperature and pressure of the outlet portion of the heater 30 in the suction pipe P1, the heating amount by the heater 30, the refrigerant flow rate, and the like, and the inlet enthalpy is the threshold. When it is less than the value corresponding to the value xin, it may be determined that the temperature difference before and after the heater is less than the reference value Tref.

Embodiment 2.
FIG. 5 is a diagram schematically showing an example of the overall configuration of the refrigeration cycle apparatus 1A according to the second embodiment. In the refrigeration cycle device 1A, a sub-pipe P2 branching from the suction pipe P1 is added to the refrigeration cycle device 1 shown in FIG. 1, and a heater 30 and

temperature sensors

10 and 20 are arranged in the sub-pipe P2. be. Since the other configurations and operations of the refrigerating cycle device 1A are the same as those of the refrigerating cycle device 1 shown in FIG. 1 above, the detailed description thereof will not be repeated here.

The auxiliary pipe P2 is formed so as to branch from the suction pipe P1 in the vicinity of the connection portion with the receiver 7 in the suction pipe P1 and join the suction pipe P1 in the vicinity of the connection portion with the compressor 2 in the suction pipe P1. The cross section of the flow path of the auxiliary pipe P2 is smaller than the cross section of the flow path of the suction pipe (main pipe) P1. The heater 30 and the

temperature sensors

10 and 20 are arranged in the auxiliary pipe P2 instead of the suction pipe P1.

The control device 100 according to the second embodiment operates the heater 30 arranged in the auxiliary pipe P2 branching from the suction pipe P1 to execute the liquid return estimation process (process shown in the flowchart of FIG. 2 above). Therefore, as compared with the refrigeration cycle device 1 according to the above-described first embodiment in which the heater 30 arranged in the suction pipe P1 having no branch to the auxiliary pipe P2 is operated, the heater 30 is heated in the liquid return estimation process. The amount of refrigerant can be reduced. As a result, the power consumption of the heater 30 required for the liquid return estimation process can be reduced.

Further, in the second embodiment, the cross section of the flow path of the auxiliary pipe P2 is smaller than the cross section of the flow path of the suction pipe (main pipe) P1. Therefore, the amount of the refrigerant to be heated by the heater 30 can be further reduced as compared with the case where the cross section of the flow path of the auxiliary pipe P2 is equal to or larger than the cross section of the flow path of the suction pipe (main pipe) P1. As a result, the power consumption of the heater 30 can be further reduced.

The cross section of the flow path of the auxiliary pipe P2 is not necessarily limited to be smaller than the cross section of the flow path of the suction pipe P1. For example, the cross section of the flow path of the auxiliary pipe P2 may be the same as the cross section of the flow path of the suction pipe P1.

Embodiment 3.
In the flowchart of FIG. 2, the control device 100 according to the first embodiment described above always operates the heater 30 while the compressor 2 is operating. On the other hand, in the control device 100 according to the third embodiment, the temperature of the refrigerant discharged from the compressor 2 while the compressor 2 is operating (hereinafter, also referred to as “compressor 2 discharge temperature”) is set. When the temperature is lower than the reference temperature, the heater 30 is operated.

Further, in the flowchart of FIG. 2 described above, a warning is output when the cumulative time (liquid back operation time) in which the sensor temperature difference ΔT is determined to be less than the reference value Tref exceeds the reference time. On the other hand, the control device 100 according to the third embodiment outputs a warning when the sensor temperature difference ΔT is less than the reference value Tref.

FIG. 6 is a flowchart showing an example of a processing procedure executed by the control device 100 according to the third embodiment when estimating the liquid return and giving a warning to the user. In this flowchart, step S30 is added, steps S20 and S22 are deleted, and step S24 is changed to step S24a with respect to FIG. 2 described above. Since the other steps of FIG. 6 (steps with the same numbers as the steps shown in FIG. 2 above) have already been described, detailed explanations will not be repeated here.

The flowchart shown in FIG. 6 is also repeatedly executed every time a predetermined condition is satisfied (for example, every predetermined cycle) while the compressor 2 is operating, as in the case of FIG. 2 described above.

First, the control device 100 determines whether or not the discharge temperature of the compressor 2 is lower than the reference temperature (step S30). It is assumed that the discharge temperature of the compressor 2 is detected by, for example, a temperature sensor (not shown) arranged on the discharge side of the compressor 2.

When the discharge temperature of the compressor 2 exceeds the reference temperature (NO in step S30), the discharge side of the compressor 2 contains a large amount of gas refrigerant, and it is unlikely that liquid return has occurred. , The control device 100 skips the subsequent processing and shifts the processing to the return. That is, even during the operation of the compressor 2, if the discharge temperature of the compressor 2 exceeds the reference temperature, the heater 30 is not operated. Therefore, the power consumption of the heater 30 can be reduced as compared with the case where the heater 30 is constantly operated while the compressor 2 is operating.

On the other hand, when the discharge temperature of the compressor 2 is lower than the reference temperature (YES in step S30), the liquid refrigerant may be contained on the discharge side of the compressor 2 and liquid return may occur, so that the control device In 100, the processing after step S10 is executed, and the liquid return estimation processing is performed.

Further, when it is determined that the sensor temperature difference ΔT is less than the reference value Tref (YES in step S18), the control device 100 outputs a warning indicating that liquid return has occurred to the warning device 120 (step). S24a).

As described above, the control device 100 according to the third embodiment operates the heater 30 when the compressor 2 is in operation and the discharge temperature of the compressor 2 is lower than the reference temperature. In other words, the control device 100 according to the third embodiment does not operate the heater 30 even while the compressor 2 is operating, if the discharge temperature of the compressor 2 exceeds the reference temperature. Therefore, the power consumption of the heater 30 can be reduced as compared with the case where the heater 30 is constantly operated while the compressor 2 is operating.

Further, the control device 100 according to the third embodiment warns a warning indicating that liquid return has occurred when it is determined that the sensor temperature difference ΔT is less than the reference value Tref (YES in step S18). Output to 120. With such a warning, it is possible to inform the user in real time how often the liquid return occurs.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of this disclosure is set forth by the claims rather than the description above and is intended to include all modifications within the meaning and scope of the claims.

1,1A refrigeration cycle device, 2 compressor, 3 flow path switching device, 4 first heat exchanger, 5 decompression device, 6 second heat exchanger, 7 receiver, 10, 20 temperature sensor, 30 heater, 40 power supply, 100 control device, 120 warning device, P1 suction pipe, P2 sub pipe, RC refrigerant circuit.

Claims

A refrigerant circuit including a compressor and a suction flow path connected to a suction port of the compressor,
The heater provided in the suction flow path and
A warning device that outputs a warning to the user and
The heater and the control device for controlling the warning device are provided.
The control device is
The required heating amount is calculated using the rotation speed of the compressor.
The heater is operated so that the heating amount by the heater becomes the required heating amount.
When the temperature difference between the first portion arranged on the upstream side of the heater and the second portion arranged on the downstream side of the heater in the suction flow path during operation of the heater is less than the reference value. A refrigeration cycle device that causes the warning device to output the warning.
The refrigerating cycle device according to claim 1, wherein the control device operates the heater so that the higher the rotation speed of the compressor, the larger the amount of heat generated by the heater.
The suction flow path includes a main flow path and a sub-flow path branched from the main flow path.
The refrigeration cycle apparatus according to claim 1 or 2, wherein the heater is provided in the sub-channel.
The refrigeration cycle apparatus according to claim 3, wherein the cross section of the sub-flow path is smaller than the cross section of the main flow path.
The control device provides the warning device when the temperature difference is less than the reference value and the time when the temperature difference is less than the reference value exceeds the reference time while the heater is in operation. The refrigerating cycle apparatus according to any one of claims 1 to 4, which outputs the warning.
The control device according to any one of claims 1 to 5, wherein the heater is operated when the compressor is in operation and the temperature of the refrigerant discharged from the compressor is lower than the reference temperature. The refrigeration cycle device described.
The first temperature sensor provided in the first part and
Further provided with a second temperature sensor provided in the second portion,
The control device calculates the temperature difference using the detection value of the first temperature sensor and the detection value of the second temperature sensor while the heater is in operation, according to any one of claims 1 to 6. The refrigeration cycle device described.