WO2020065999A1

WO2020065999A1 - Outdoor unit for refrigeration cycle device, refrigeration cycle device, and air conditioning device

Info

Publication number: WO2020065999A1
Application number: PCT/JP2018/036524
Authority: WO
Inventors: 智隆石川; 亮築山
Original assignee: 三菱電機株式会社
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-04-02
Also published as: JP7196187B2; JPWO2020065999A1; CN112714853B; CN112714853A

Abstract

A bypass circuit is branched from piping (83) and is configured to return a part of a refrigerant flowing through the piping (83), to a compressor (10) without causing the part of the refrigerant to flow through an indoor unit (3). The bypass circuit includes a refrigerant shortage detection circuit (70). The refrigerant shortage detection circuit (70) includes a capillary tube (71) and a heater (72). When a refrigerant having flowed through the heating section of the heater (72) is in a superheated state, a control section (100) determines that there is a shortage of the refrigerant. A gas-liquid separation mechanism is configured so that, when a gas-liquid two-phase refrigerant flows through the piping (83), the gas-liquid separation mechanism separates the gas refrigerant from the gas-liquid two-phase refrigerant at a branch section (88), where the bypass circuit branches from the piping (83), and causes the separated gas refrigerant to flow to the bypass circuit.

Description

Outdoor unit of refrigeration cycle device, refrigeration cycle device, and air conditioner

The present disclosure relates to an outdoor unit of a refrigeration cycle device, a refrigeration cycle device, and an air conditioner.

WO 2016/135904 discloses a refrigeration system. This refrigerating apparatus includes a heat source side unit and a use side unit (indoor unit) connected to the heat source side unit by a pipe. The heat source side unit includes a compressor, a condenser, and a subcooler. The use side unit includes an expansion valve and an evaporator. In this refrigeration apparatus, the suitability of the amount of refrigerant charged in the refrigerant circuit is determined using the temperature efficiency of the subcooler. The temperature efficiency is a value obtained by dividing the degree of supercooling of the refrigerant at the outlet of the subcooler by the maximum temperature difference of the subcooler. According to this refrigeration apparatus, it is possible to detect a shortage of the refrigerant in the refrigerant circuit (see Patent Document 1).

WO 2016/135904 pamphlet

冷凍 In the refrigeration apparatus described in Patent Document 1, unless the amount of decrease in the refrigerant becomes large to some extent, the state of the refrigerant shortage does not remarkably appear in the degree of supercooling or the temperature efficiency, so that the refrigerant shortage may not be accurately detected. Further, in an operation state in which supercooling cannot be performed even when the refrigerant amount is normal, such as during overload operation, the above-described refrigeration apparatus can accurately detect a decrease in the refrigerant amount based on a decrease in the degree of subcooling. Detection accuracy may be reduced.

The present disclosure has been made in order to solve such a problem, and an object of the present disclosure is to provide an outdoor unit of a refrigeration cycle device capable of accurately detecting a shortage of refrigerant sealed in a refrigerant circuit, and a refrigeration cycle including the same. Device, as well as an air conditioner.

The outdoor unit of the present disclosure is an outdoor unit of a refrigeration cycle device, which is a compressor that compresses a refrigerant, a condenser that condenses a refrigerant output from the compressor, a bypass circuit, a control device, and a gas-liquid separator. And a mechanism. The bypass circuit is branched from a pipe on the outlet side of the condenser, and is configured to return a part of the refrigerant flowing through the pipe to the compressor without passing through the indoor unit. The bypass circuit includes a detection circuit for detecting a shortage of the refrigerant sealed in the refrigeration cycle device. The detection circuit includes a flow rate adjusting unit configured to adjust a flow rate of the refrigerant flowing through the bypass circuit, and a heating unit configured to heat the refrigerant that has passed through the flow rate adjusting unit. The control device determines that the refrigerant enclosed in the refrigeration cycle device is insufficient when the refrigerant that has passed through the heating unit has a degree of superheat. The gas-liquid separation mechanism is configured to separate the gas refrigerant from the gas-liquid two-phase refrigerant and to flow to the bypass circuit when the gas-liquid two-phase refrigerant flows at the branch at a branch where the bypass circuit branches from the pipe. Is done.

なければ In this outdoor unit, if the refrigerant is not short, the refrigerant flowing through the heating unit is in a gas-liquid two-phase state, so that the refrigerant passing through the heating unit is unlikely to have a degree of superheat. On the other hand, when the shortage of the refrigerant occurs, the refrigerant flowing through the heating unit evaporates and becomes a gas refrigerant (single-phase gas), and the refrigerant that has passed through the heating unit has a degree of superheat. Therefore, in this outdoor unit, when the degree of superheat is generated in the refrigerant that has passed through the heating unit, it is determined that the refrigerant is insufficient.

(4) When a shortage of the refrigerant occurs, the refrigerant does not condense in the condenser, and the refrigerant enters a gas-liquid two-phase state on the outlet side of the condenser. In this case, when the liquid refrigerant flows into the bypass circuit, even if the refrigerant passes through the heating unit, the refrigerant does not completely evaporate, and the refrigerant that has passed through the heating unit may not have a degree of superheat. Therefore, in this outdoor unit, a gas-liquid separation mechanism is provided at a branch portion where the bypass circuit branches, and when refrigerant shortage occurs, gas refrigerant separated from the gas-liquid two-phase refrigerant flows to the bypass circuit. . Accordingly, when a shortage of the refrigerant occurs, a gas refrigerant or a refrigerant having an extremely high degree of dryness flows into the bypass circuit, so that the degree of superheat can be reliably generated in the refrigerant that has passed through the heating unit. Therefore, according to this outdoor unit, it is possible to suppress erroneous detection that the shortage of the refrigerant has not occurred even though the shortage of the refrigerant has occurred.

In addition, when the refrigerant shortage does not occur, the outlet side of the condenser becomes the liquid refrigerant, and the liquid refrigerant flows into the bypass circuit, so that all the refrigerant passing through the heating unit evaporates, which may cause a degree of superheat. Sex is low.

According to the outdoor unit, the refrigeration cycle device, and the air conditioner of the present disclosure, it is possible to accurately detect the shortage of the refrigerant sealed in the refrigerant circuit.

1 is an overall configuration diagram of a refrigeration apparatus using an outdoor unit according to Embodiment 1 of the present disclosure. FIG. 7 is a ph diagram showing a relationship between the pressure of the refrigerant and the enthalpy in a normal state where the shortage of the refrigerant does not occur. FIG. 4 is a ph diagram showing the state of the refrigerant when the refrigerant is insufficient. 3 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to Embodiment 1. FIG. 2 is a flowchart illustrating an example of a processing procedure of a refrigerant shortage determination executed by the control device illustrated in FIG. 1. FIG. 13 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to Embodiment 2. FIG. 14 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to Embodiment 3. FIG. 15 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to a fourth embodiment. It is a figure showing other composition of a gas-liquid separation mechanism. It is a figure showing composition of an outdoor unit in a modification. 1 is an overall configuration diagram of an air conditioner including a refrigeration cycle in which an outdoor unit of the present disclosure is used.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram of a refrigeration apparatus using an outdoor unit according to Embodiment 1 of the present disclosure. Note that FIG. 1 functionally illustrates the connection relationship and arrangement of each device in the refrigeration apparatus, and does not necessarily indicate the arrangement in a physical space.

冷凍 Referring to FIG. 1, refrigeration apparatus 1 includes outdoor unit 2 and indoor unit 3. The outdoor unit 2 includes a compressor 10, a condenser 20, a fan 22, and

pipes

80, 83, 85. The outdoor unit 2 further includes

pipes

86 and 87, a refrigerant shortage detection circuit 70, a pressure sensor 90, and a control device 100. The indoor unit 3 includes an expansion valve 50, an evaporator 60, a fan 62, and a pipe 84. The indoor unit 3 is connected to the outdoor unit 2 through

pipes

83 and 85.

The pipe 80 connects the discharge port of the compressor 10 and the condenser 20. The pipe 83 connects the condenser 20 and the expansion valve 50. The pipe 84 connects the expansion valve 50 and the evaporator 60. The pipe 85 connects the evaporator 60 and the suction port of the compressor 10. The pipe 86 branches from a branch portion 88 of the pipe 83, and connects the pipe 83 and the refrigerant shortage detection circuit 70. The pipe 87 connects the refrigerant shortage detection circuit 70 and the pipe 85.

The compressor 10 compresses the refrigerant sucked from the pipe 85 and outputs the compressed refrigerant to the pipe 80. The compressor 10 is configured to adjust the rotation speed according to a control signal from the control device 100. By adjusting the rotation speed of the compressor 10, the circulation amount of the refrigerant is adjusted, and the capacity of the refrigeration apparatus 1 can be adjusted. Various types can be used for the compressor 10, and for example, a scroll type, a rotary type, a screw type, and the like can be used.

The condenser 20 condenses the refrigerant output from the compressor 10 to the pipe 80 and outputs the refrigerant to the pipe 83. The condenser 20 is configured such that the high-temperature and high-pressure gas refrigerant output from the compressor 10 performs heat exchange (radiation) with the outside air. By this heat exchange, the refrigerant is condensed and changes to a liquid phase. The fan 22 supplies the outside air to the condenser 20 where the refrigerant performs heat exchange in the condenser 20. By adjusting the rotation speed of the fan 22, the refrigerant pressure (high-pressure side pressure) on the outlet side of the compressor 10 can be adjusted.

(4) The expansion valve 50 reduces the pressure of the refrigerant output from the condenser 20 to the pipe 83 and outputs the reduced pressure to the pipe 84. When the opening degree of the expansion valve 50 is changed in the closing direction, the refrigerant pressure on the exit side of the expansion valve 50 decreases, and the dryness of the refrigerant increases. When the opening of the expansion valve 50 is changed in the opening direction, the refrigerant pressure on the outlet side of the expansion valve 50 increases, and the dryness of the refrigerant decreases.

The evaporator 60 evaporates the refrigerant output from the expansion valve 50 to the pipe 84 and outputs the refrigerant to the pipe 85. The evaporator 60 is configured such that the refrigerant decompressed by the expansion valve 50 performs heat exchange (heat absorption) with the air in the indoor unit 3. The refrigerant evaporates by passing through the evaporator 60 to become superheated steam. The fan 62 supplies to the evaporator 60 external air in which the refrigerant performs heat exchange in the evaporator 60.

The refrigerant shortage detection circuit 70 is provided between a pipe 86 branched from the pipe 83 and a pipe 87 connected to the pipe 85. The pipe 86, the refrigerant shortage detection circuit 70, and the pipe 87 constitute a “bypass circuit” that returns a part of the refrigerant on the outlet side of the condenser 20 to the compressor 10 without passing through the indoor unit 3.

The refrigerant shortage detection circuit 70 includes a capillary tube 71, a heater 72, a temperature sensor 73, and an electromagnetic valve 74. The capillary tube 71 is connected between the pipe 86 and the pipe 87, and adjusts the flow rate of the refrigerant flowing through the bypass circuit. As the refrigerant passes through the capillary tube 71, the pressure of the refrigerant decreases. Accordingly, when the liquid refrigerant is supplied from the pipe 86 (when the refrigerant amount is normal), the refrigerant that has passed through the capillary tube 71 is in a gas-liquid two-phase state with a low dryness. On the other hand, when the gas-liquid two-phase refrigerant is supplied from the pipe 86 (when the refrigerant is insufficient), the refrigerant that has passed through the capillary tube 71 is in a gas-liquid two-phase state with a high degree of dryness.

The heater 72 and the temperature sensor 73 are provided on the pipe 87. The heater 72 heats the refrigerant that has passed through the capillary tube 71. The enthalpy of the refrigerant is increased by being heated by the heater 72. The heater 72 basically heats the refrigerant from outside the pipe 87, but may be installed inside the pipe 87 in order to more reliably transfer heat from the heater 72 to the refrigerant.

(4) The temperature sensor 73 detects the temperature T of the refrigerant flowing through the pipe 87 downstream of the heating unit by the heater 72, and outputs the detected value to the control device 100. The temperature sensor 73 is also installed outside the pipe 87, but may be installed inside the pipe 87 to more reliably detect the temperature of the refrigerant. The principle and method of refrigerant shortage detection by the refrigerant shortage detection circuit 70 will be described later in detail.

The electromagnetic valve 74 is provided in the pipe 86 upstream of the capillary tube 71 and opens and closes according to an instruction from the control device 100. When the solenoid valve 74 is opened, the refrigerant flows through the bypass circuit, and the refrigerant shortage detection circuit 70 can detect the refrigerant shortage. When the solenoid valve 74 is in the closed state, the flow of the refrigerant in the bypass circuit is shut off, so that the refrigerant shortage detection cannot be executed. Note that the solenoid valve 74 may be provided in a pipe 87 downstream of the capillary tube 71.

The pressure sensor 90 detects the refrigerant pressure (low pressure side pressure) LP on the suction side of the compressor 10 and outputs the detected value to the control device 100. Since the pipe 87 of the bypass circuit is connected to the pipe 85 on the suction side of the compressor 10, if there is no pressure loss at the connection between the pipe 87 and the pipe 85, the pressure sensor 90 detects the pressure inside the pipe 87 of the bypass circuit. Can be detected.

The control device 100 includes a CPU (Central Processing Unit) 102, a memory 104 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown) for inputting and outputting various signals, and the like. It is comprised including. The CPU 102 executes a program stored in the ROM by expanding the program in the RAM or the like. The program stored in the ROM is a program in which the processing procedure of the control device 100 is described. The control device 100 controls each device in the outdoor unit 2 according to these programs. This control is not limited to processing by software, and processing by dedicated hardware (electronic circuit) is also possible.

<Explanation of refrigerant shortage detection>
Hereinafter, a method of detecting a refrigerant shortage using the refrigerant shortage detection circuit 70 will be described. The shortage of the refrigerant occurs when the initial charge amount of the refrigerant in the refrigerant circuit is insufficient or when the refrigerant leaks after the start of use.

FIG. 2 is a ph diagram showing the relationship between refrigerant pressure and enthalpy in a normal state where there is no shortage of refrigerant. Hereinafter, when the shortage of the refrigerant has not occurred and the refrigerant amount is within an appropriate range, the refrigerant amount is referred to as “normal”. Referring to FIG. 2, the vertical axis represents pressure p, and the horizontal axis represents specific enthalpy h (kJ / kg) (hereinafter, simply referred to as “enthalpy”).

A solid line S1 (hereinafter, referred to as "cycle 1") connecting points P11 to P14 indicates the state of the refrigerant when the refrigerant amount is normal. In cycle 1, point P14 → point P11 indicates compression of the refrigerant in the compressor 10 (isentropic change), and point P11 → point P12 indicates equal pressure cooling in the condenser 20. Further, a point P12 → point P13 indicates the pressure reduction in the expansion valve 50, and a point P13 → point P14 indicates the equal pressure heating in the evaporator 60.

Points A1, B1, and C1 indicate states of the refrigerant at points A, B, and C on the bypass circuit shown in FIG. 1 when the refrigerant amount is normal. A dotted line L11 connecting the point A1 and the point B1 indicates pressure reduction by the capillary tube 71 of the refrigerant shortage detection circuit 70. A dotted line L12 connecting the point B1 and the point C1 indicates equal pressure heating by the heater 72 of the refrigerant shortage detection circuit 70. Since the outlet pipe 87 of the bypass circuit is connected to the outlet pipe 85 of the evaporator 60, the outlet pressure of the capillary tube 71 (the pressure at point B1) is equal to the pressure at the evaporator 60 (point P13). Pressure). The refrigerant downstream of the heater 72 (point C1) is in a gas-liquid two-phase state, and the degree of superheat SH is zero.

FIG. 3 is a ph diagram showing the state of the refrigerant when the refrigerant is insufficient. Referring to FIG. 3, solid line S2 (hereinafter, referred to as “cycle 2”) connecting points P21 to P24 indicates the state of the refrigerant when the refrigerant amount is insufficient. In cycle 2, point P24 → point P21 indicates compression of the refrigerant in the compressor 10 (isentropic change), and point P21 → point P22 indicates equal pressure cooling in the condenser 20. In addition, a point P22 → point P23 indicates pressure reduction in the expansion valve 50, and a point P23 → point P24 indicates equal pressure heating in the evaporator 60.

As illustrated, when the refrigeration apparatus 1 is operated in a state where the amount of the refrigerant is insufficient, the condensation of the refrigerant in the condenser 20 does not proceed, the degree of supercooling of the refrigerant decreases, and the refrigerant at the outlet side of the condenser 20 decreases. Is in a gas-liquid two-phase state (point p22). Points A2, B2, and C2 indicate states of the refrigerant at points A, B, and C on the bypass circuit shown in FIG. 1 when the refrigerant amount is insufficient. A dotted line L21 connecting the points A2 and B2 indicates the pressure reduction by the capillary tube 71 of the refrigerant shortage detection circuit 70. A dotted line L22 connecting the points B2 and C2 indicates equal pressure heating by the heater 72 of the refrigerant shortage detection circuit 70.

As will be described in detail later, in the outdoor unit 2 of the present disclosure, a gas-liquid separation mechanism is provided at a branch portion 88 (FIG. 1) where the bypass circuit branches from the pipe 83 on the outlet side of the condenser 20, and there is insufficient refrigerant. When this occurs, the gas refrigerant (gas-phase refrigerant) separated from the gas-liquid two-phase refrigerant output from the condenser 20 flows to the bypass circuit. As a result, when a shortage of refrigerant occurs, a gas refrigerant or a refrigerant having a very high degree of dryness flows into the bypass circuit (point A2). The refrigerant on the outlet side (point B2) of the capillary tube 71 is also a gas refrigerant or a refrigerant having extremely high dryness. Therefore, the refrigerant downstream of the heater 72 (point C2) is heated by the heater 72 and surely becomes a gas refrigerant having a superheat degree SH (SH> 0).

As described above, when the refrigerant amount is insufficient, the refrigerant that has passed through the heating unit of the heater 72 in the refrigerant shortage detection circuit 70 provided in the bypass circuit has a degree of superheat SH. On the other hand, when the refrigerant amount is normal, the superheat degree SH does not occur in the refrigerant that has passed through the heating unit (SH = 0). Therefore, in the refrigeration apparatus 1, it is determined whether or not the refrigerant is short based on the degree of superheat SH of the refrigerant that has passed through the heating unit of the refrigerant shortage detection circuit 70.

According to the outdoor unit 2, when the refrigerant is in a gas-liquid two-phase state at the outlet side of the condenser 20 due to a shortage of the refrigerant amount, the superheat degree SH is generated in the refrigerant that has passed through the heating unit of the refrigerant shortage detection circuit 70. Therefore, the shortage of the refrigerant can be immediately detected. Further, even in an operation state in which supercooling cannot be performed even when the refrigerant amount is normal, such as during an overload operation, a refrigerant shortage can be detected based on the degree of superheat SH.

The superheat degree SH of the refrigerant that has passed through the heating unit of the refrigerant shortage detection circuit 70 can be calculated from the detection value of the temperature sensor 73 and the detection value of the pressure sensor 90. That is, the detection value of the temperature sensor 73 indicates the temperature of the refrigerant heated by the heater 72. Further, the detection value of the pressure sensor 90 indicates the pressure of the refrigerant in the heating section by the heater 72. From the refrigerant pressure, the evaporation temperature of the refrigerant in the heating section (the saturation temperature of the refrigerant on the low pressure side in the refrigeration apparatus 1) can be calculated. Then, the superheat degree SH of the refrigerant heated by the heater 72 can be calculated by subtracting the evaporation temperature calculated from the detected value of the pressure sensor 90 from the detected value of the temperature sensor 73.

<Configuration of gas-liquid separation mechanism>
As described above, in the outdoor unit 2, the refrigerant shortage is detected based on the degree of superheat SH of the refrigerant that has passed through the heating unit of the refrigerant shortage detection circuit 70. Specifically, if the superheat degree SH of the refrigerant passing through the heating unit is 0, the refrigerant amount is normal, and if the refrigerant passing through the heating unit has a superheat degree (SH> 0), the refrigerant shortage occurs. Is determined to have occurred.

Therefore, in order to accurately detect the shortage of the refrigerant, it is necessary to ensure that the refrigerant heated by the heater 72 has the degree of superheat SH when the shortage of the refrigerant occurs. When the shortage of the refrigerant occurs, the condensation of the refrigerant does not proceed in the condenser 20, and the refrigerant enters a gas-liquid two-phase state on the outlet side of the condenser 20. In this case, when the liquid refrigerant (liquid-phase refrigerant) flows into the bypass circuit, even if the refrigerant is heated by the heater 72, the refrigerant does not completely evaporate, and the refrigerant heated by the heater 72 may not have the degree of superheat SH. is there.

Therefore, in outdoor unit 2 according to the first embodiment, at a branch portion 88 (FIG. 1) where the bypass circuit branches off from pipe 83, the bypass circuit is configured to branch upward from pipe 83 (gas and liquid). Separation mechanism). With such a configuration, when a shortage of the refrigerant occurs, the gas refrigerant can be separated from the gas-liquid two-phase refrigerant at the outlet side of the condenser 20 and flow to the bypass circuit. Since the gas refrigerant or the extremely dry refrigerant flows into the bypass circuit, when the refrigerant is heated by the heater 72, the superheat SH is definitely generated in the refrigerant. Thus, it is possible to suppress the erroneous detection that the refrigerant amount is normal due to the superheat degree SH not being generated in the refrigerant heated by the heater 72 despite the shortage of the refrigerant.

FIG. 4 is a diagram illustrating an example of a configuration of the gas-liquid separation mechanism according to the first embodiment. In the figure, the direction of arrow U indicates a vertically upward direction, and the direction of arrow D indicates a vertically downward direction. Referring to FIG. 4, pipe 83 on the outlet side of condenser 20 is disposed at least in the vicinity of branch portion 88 where the bypass circuit (pipe 86) branches, and is arranged laterally with respect to the vertical direction. The pipe 86 is connected to the pipe 83 so that the bypass circuit branches vertically upward from the pipe 83 at the branch portion 88.

With such a configuration, when the gas-liquid two-phase refrigerant 76 composed of the liquid refrigerant and the gas refrigerant flows through the pipe 83 due to the shortage of the refrigerant, the gravity prevents the liquid refrigerant having a large specific gravity from flowing into the pipe 86. At the same time, a gas refrigerant having a small specific gravity can flow through the pipe 86. The gas refrigerant flows to the pipe 86 because the pipe 87 on the outlet side of the bypass circuit is connected to the suction side of the compressor 10, that is, the low pressure side of the refrigerating apparatus 1. Is because a negative pressure is generated.

Note that, depending on the flow rate of the refrigerant, a part of the liquid refrigerant may flow into the pipe 86 along with the gas refrigerant, but at least the dryness of the refrigerant flowing into the pipe 86 by such a gas-liquid separation mechanism. Can be made higher than the dryness of the refrigerant flowing through the pipe 83 upstream of the branch portion 88.

In order to prevent the liquid refrigerant from flowing into the pipe 86 when the gas-liquid two-phase refrigerant is flowing through the pipe 83 due to lack of the refrigerant, it is preferable that the inner diameter d of the pipe 86 be larger than the reference inner diameter d0. . Here, the reference inner diameter d0 is the inner diameter d when the flow rate of the gas refrigerant flowing from the pipe 83 to the pipe 86 becomes zero penetration flow rate when the gas-liquid two-phase refrigerant flows through the pipe 83. Zero penetration is a phenomenon in which when a gas-liquid two-phase refrigerant rises in a pipe and flows, the liquid refrigerant rises along the pipe wall with the gas refrigerant, and the zero penetration flow rate is It is the flow rate of the refrigerant when the refrigerant starts to rise on the tube wall. The zero penetration flow rate can be calculated from the inner diameter of the pipe, the density of the gas refrigerant, and the density of the liquid refrigerant using a known method. By making the inner diameter d of the pipe 86 larger than the reference inner diameter d0, the flow rate of the gas refrigerant flowing into the pipe 86 becomes lower than the zero penetration flow rate, so that the liquid refrigerant can be suppressed from flowing into the pipe 86. .

By providing such a gas-liquid separation mechanism, when a refrigerant shortage occurs, a gas refrigerant or an extremely dry refrigerant flows into the bypass circuit. Superheat can be created.

On the other hand, when the refrigerant amount is normal, the liquid refrigerant cooled to a supercooled state flows through the pipe 83. Therefore, even if the gas-liquid separation mechanism as described above is provided, the liquid refrigerant Flows in. Therefore, even if the refrigerant is heated by the heater 72 in the refrigerant shortage detection circuit 70, the refrigerant does not entirely evaporate, and the refrigerant that has passed through the heating unit does not have a degree of superheat.

In the above description, the pipe 86 constituting the bypass pipe is branched vertically upward from the pipe 83, but the branch direction of the pipe 86 does not necessarily have to be vertical. The branching direction of the pipe 86 may be any direction as long as the liquid refrigerant having a large specific gravity can be prevented from flowing into the pipe 86 by gravity. By setting the branching direction of the pipe 86 to be vertically upward, the gas refrigerant can be most effectively separated from the gas-liquid two-phase refrigerant by using gravity.

FIG. 5 is a flowchart illustrating an example of a processing procedure for refrigerant shortage determination performed by the control device 100 illustrated in FIG. 1. A series of processes shown in this flowchart is repeatedly executed while the refrigeration apparatus 1 performs a steady operation.

制御 Referring to FIG. 5, control device 100 determines whether or not it is time to execute refrigerant shortage determination control (step S10). The refrigerant shortage determination control is executed, for example, once a day. When it is determined that it is not time to execute the refrigerant shortage determination control (NO in step S10), control device 100 shifts the process to the return without executing the subsequent series of processes. Note that, without providing such a determination process in the flowchart, when it is time to execute the refrigerant shortage determination control, a series of processes from step S20 shown in the flowchart may be started.

If it is determined in step S10 that it is time to execute the refrigerant shortage determination control (YES in step S10), control device 100 turns on (opens) solenoid valve 74 (step S20) and turns on heater 72. (Operation) (step S30).

Next, when a predetermined time sufficient for heating of the refrigerant by heater 72 to reach a steady state has elapsed (YES in step S40), control device 100 obtains a detected value of temperature T from temperature sensor 73. At the same time, the detection value of the pressure LP is obtained from the pressure sensor 90 (Step S50).

Then, the control device 100 calculates the degree of superheat SH of the refrigerant that has passed through the heating unit, using the obtained detected values of the temperature T and the pressure LP (Step S60). Specifically, the relationship between the refrigerant pressure and the evaporation temperature (saturation temperature) is stored in advance in the ROM of the memory 104 as a map, a table, or the like, and the control device 100 uses the map or the like to Is calculated from the detected value of the pressure LP indicating the pressure of the refrigerant in the heating section. Then, control device 100 calculates the degree of superheat SH of the refrigerant heated by heater 72 by subtracting the calculated evaporation temperature from temperature T obtained in step S50.

When the superheat degree SH of the refrigerant downstream of the heater 72 is calculated, the control device 100 determines whether the superheat degree SH is higher than a threshold value SHth (step S70). This threshold value SHth is for determining whether or not the superheat degree SH has occurred in the refrigerant heated by the heater 72, and is appropriately set based on the calculation accuracy of the superheat degree SH.

If it is determined in step S70 that superheat degree SH is higher than threshold value SHth (YES in step S70), control device 100 determines that the refrigerant amount is insufficient (step S80). An alarm indicating that a shortage of refrigerant has occurred is output (step S90). Thereafter, the control device 100 turns off (stops) the heater 72 (step S100) and turns off (closes) the solenoid valve 74 (step S110). Thereafter, control device 100 shifts the process to return, and the refrigerant shortage determination process ends.

If it is determined in step S70 that superheat degree SH is equal to or smaller than threshold value SHth (NO in step S70), control device 100 shifts the process to step S100 without executing steps S80 and S90. Then, the heater 72 is turned off (stopped) and the solenoid valve 74 is turned off (closed). That is, in this case, it is determined that the refrigerant amount is normal.

As described above, in the first embodiment, it is determined whether a refrigerant shortage has occurred based on the degree of superheat SH of the refrigerant heated by the heater 72 of the refrigerant shortage detection circuit 70. As a result, when the refrigerant becomes short in gas-liquid two-phase state on the outlet side of the condenser 20 due to the shortage of the refrigerant, the above-described degree of superheat SH is generated, so that the shortage of the refrigerant can be immediately detected. Further, even in an operation state in which supercooling cannot be performed even when the refrigerant amount is normal, such as during an overload operation, a refrigerant shortage can be detected based on the degree of superheat SH.

In the first embodiment, the bypass circuit (the pipe 86) is configured to branch upward from the pipe 83. Accordingly, when a shortage of the refrigerant occurs, the gas refrigerant can be separated from the refrigerant in the gas-liquid two-phase at the outlet side of the condenser 20 and flow to the bypass circuit. Since the gas refrigerant or the extremely dry refrigerant flows into the bypass circuit, the refrigerant heated by the heater 72 surely generates the superheat degree SH. Accordingly, it is possible to suppress the erroneous detection that the refrigerant amount is normal due to the absence of the above-described degree of superheat SH despite the shortage of the refrigerant.

Embodiment 2 FIG.
The second embodiment differs from the first embodiment in the configuration of the gas-liquid separation mechanism.

FIG. 6 is a diagram showing an example of the configuration of the gas-liquid separation mechanism according to the second embodiment. As in FIG. 4, the direction of arrow U indicates a vertically upward direction, and the direction of arrow D indicates a vertically downward direction. Referring to FIG. 6, piping 83 on the outlet side of condenser 20 includes a first portion 110 and a second portion 112. The first portion 110 is disposed laterally with respect to the vertical direction. The second portion 112 is provided downstream of the first portion 110 and is disposed to extend vertically downward from the branch portion 88 in a direction opposite to the pipe 86.

With such a configuration, when the gas-liquid two-phase refrigerant including the liquid refrigerant and the gas refrigerant flows through the pipe 83 due to the shortage of the refrigerant, the liquid refrigerant having a large specific gravity easily flows to the second portion 112 by gravity. . Thereby, gas-liquid separation is performed more effectively than the configuration shown in FIG. Therefore, the gas refrigerant can flow into the pipe 86 more remarkably than in the first embodiment.

Note that, also in the second embodiment, it is preferable that the inner diameter d of the pipe 86 be larger than the reference inner diameter d0. Accordingly, the flow rate of the gas refrigerant flowing into the pipe 86 can be made lower than the zero penetration flow rate, so that the flow of the liquid refrigerant from the pipe 83 to the pipe 86 when the shortage of the refrigerant occurs is suppressed. Can be.

In the second embodiment as well, when the refrigerant amount is normal, the liquid refrigerant cooled to the supercooled state flows through the pipe 83, and thus the gas-liquid separation mechanism as described above is provided. Also, the liquid refrigerant flows into the bypass circuit. Therefore, even if the refrigerant is heated by the heater 72 in the refrigerant shortage detection circuit 70, the refrigerant does not completely evaporate, and the refrigerant that has passed through the heating unit does not have a degree of superheat.

The configuration of the outdoor unit 2 according to the second embodiment and the refrigerating apparatus 1 using the same are the same as the configuration shown in FIG. 1 except for the configuration of the gas-liquid separation mechanism described above.

As described above, according to the second embodiment, when a shortage of refrigerant occurs, the gas refrigerant can be more effectively separated from the gas-liquid two-phase refrigerant flowing through the pipe 83 and flown to the bypass circuit. . As a result, it is possible to more stably detect the refrigerant shortage without erroneous detection.

Embodiment 3 FIG.
In the third embodiment, the configuration of the gas-liquid separation mechanism in the second embodiment further includes a configuration in which a swirling flow is generated in the branch portion 88 in the refrigerant flowing through the pipe 83. Thus, when a refrigerant shortage occurs, centrifugal separation by a swirling flow is added, so that more effective gas-liquid separation is performed, and gas refrigerant can flow into the pipe 86 more remarkably.

FIG. 7 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to the third embodiment. FIG. 7 is a diagram when the branch portion 88 where the pipe 86 branches from the pipe 83 is viewed from vertically above. The configuration of the gas-liquid separation mechanism when the branch portion 88 is viewed from the side is the same as that of the gas-liquid separation mechanism according to the second embodiment shown in FIG.

Referring to FIG. 7, in the third embodiment, when branch portion 88 is viewed from vertically above, center line O1 of first portion 110 of pipe 83 and center line O2 of second portion 112 are offset. have. Therefore, when the refrigerant flows from the first portion 110 to the second portion 112 in the pipe 83, a swirling flow is generated around the center line O2.

Thereby, when the refrigerant that has become a gas-liquid two-phase at the outlet side of the condenser 20 due to the shortage of the refrigerant flows from the first portion 110 to the second portion 112, the liquid refrigerant having a high specific gravity is centrifugally moved to the second portion 112. The gas refrigerant flows along the inner wall and gathers at the center of the pipe. As described above, the gas refrigerant can be more effectively separated from the gas-liquid two-phase refrigerant using the centrifugal separation by the swirling flow, and the separated gas refrigerant can flow into the pipe 86.

According to the third embodiment, when a shortage of the refrigerant occurs, the gas refrigerant can be more effectively separated from the gas-liquid two-phase refrigerant flowing through the pipe 83 and flown to the bypass circuit. As a result, it is possible to more stably detect the shortage of the refrigerant without erroneous detection.

Embodiment 4 FIG.
According to the gas-liquid separation mechanism described in each of the above embodiments, a part of the liquid refrigerant may become droplets and flow into the bypass circuit together with the gas refrigerant. Therefore, in the fourth embodiment, the pipe 86 is provided with a mesh-like member that captures droplets flowing into the bypass circuit together with the gas refrigerant from the branch portion 88.

FIG. 8 is a diagram illustrating an example of a configuration of a gas-liquid separation mechanism according to the fourth embodiment. Referring to FIG. 8, the gas-liquid separation mechanism further includes a mesh member 120 in the configuration of the first embodiment shown in FIG. The mesh member 120 is provided on the pipe 86 of the bypass circuit, and is provided at a rising portion of the pipe 86 from the branch portion 88.

When the gas-liquid two-phase refrigerant is flowing through the pipe 83 due to the shortage of the refrigerant, the mesh member 120 unexpectedly flies from the branch 88 while passing the gas refrigerant separated at the branch 88 through the mesh. Capture incoming droplets. The mesh member 120 cannot capture all the droplets flying from the branch portion 88, but can capture at least a part of the droplets. The trapped droplets fall into the branch portion 88 as a lump as the trapped amount increases.

(4) When the amount of the refrigerant is normal and the liquid refrigerant flows from the pipe 83 to the pipe 86, the mesh member 120 allows the liquid refrigerant to pass through the eye.

According to the fourth embodiment, by providing the mesh member 120, when the gas-liquid two-phase refrigerant flows through the pipe 83 due to the shortage of the refrigerant, the liquid refrigerant (droplets) is supplied to the refrigerant shortage detection circuit 70. It is possible to avoid that the refrigerant that flows in and is heated by the heater 72 does not generate the degree of superheat SH.

In the above description, the mesh member 120 is further provided in the configuration of the first embodiment shown in FIG. 4, but as shown in FIG. 9, the second embodiment or the second embodiment shown in FIG. A mesh member 120 may be further provided in the configuration of the third embodiment.

Other modified examples.
In each of the above embodiments, the temperature sensor 73 is provided downstream of the heater 72, and the superheat degree is calculated from the temperature T detected by the temperature sensor 73 and the evaporation temperature calculated from the pressure LP detected by the pressure sensor 90. Although the SH is calculated, a temperature sensor for detecting the evaporation temperature (low pressure saturation temperature) is further provided between the capillary tube 71 and the heater 72, and the detected value of the temperature sensor is different from the detected value of the temperature sensor 73. The degree of superheat SH may be measured by subtraction.

設ける By providing such a temperature sensor, the measurement accuracy of the degree of superheat SH can be improved, and the accuracy of detecting the shortage of the refrigerant can be improved. On the other hand, a refrigeration apparatus is generally provided with a pressure sensor for detecting the pressure on the suction side of the compressor. According to each of the above-described embodiments in which such a pressure sensor 90 is used for deriving the degree of superheat SH, an existing pressure sensor 90 can be used without separately providing a temperature sensor between the capillary tube 71 and the heater 72. Refrigerant shortage detection can be performed.

Further, in each of the above-described embodiments, the bypass circuit is branched from the pipe 83 on the outlet side of the condenser 20, but as shown in FIG. When the exchanger 40 is further provided, a bypass circuit may be branched from a pipe 82 between the liquid reservoir 30 and the heat exchanger 40.

(4) Generally, such a liquid reservoir and a heat exchanger are often provided in a refrigerator. If the refrigerant amount is normal, the liquid refrigerant is stored in the liquid reservoir 30, and the liquid refrigerant flows through the pipe 82 and the pipe 86 of the bypass circuit. On the other hand, when a shortage of the refrigerant occurs, the liquid refrigerant is not stored in the liquid reservoir 30, so that a gas-liquid two-phase or gas-phase single-phase refrigerant flows through the pipe 86 of the bypass circuit. Therefore, even with such a configuration, the refrigerant shortage can be detected by the refrigerant shortage detection circuit 70 provided in the bypass circuit.

Further, in each of the above-described embodiments and modifications, the outdoor unit and the refrigeration apparatus mainly used for a warehouse, a showcase, and the like have been representatively described. However, the outdoor unit according to the present disclosure may be configured as shown in FIG. Also, the present invention is applicable to an air conditioner 200 using a refrigeration cycle.

実施 The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 Refrigerator, 2 outdoor unit, 3 indoor unit, 10 compressor, 20 condenser, 22, 42, 62 fan, 30 reservoir, 40 heat exchanger, 50 expansion valve, 60 evaporator, 70 refrigerant shortage detection circuit , 71 capillary tube, 72 heater, 73 temperature sensor, 74 solenoid valve, 80-87 pipe, 88 branch, 90 pressure sensor, 100 control device, 102 CPU, 104 memory, 110 first part, 112 second part, 120 Mesh member, 200 ° air conditioner.

Claims

An outdoor unit of a refrigeration cycle device,
A compressor for compressing the refrigerant,
A condenser for condensing the refrigerant output from the compressor,
A bypass circuit branched from a pipe on the outlet side of the condenser and configured to return a part of the refrigerant flowing through the pipe to the compressor without passing through an indoor unit,
The bypass circuit includes a detection circuit for detecting a shortage of the refrigerant sealed in the refrigeration cycle device,
The detection circuit includes:
A flow rate adjustment unit configured to adjust the flow rate of the refrigerant flowing through the bypass circuit,
A heating unit configured to heat the refrigerant that has passed through the flow rate adjustment unit,
When the degree of superheat has occurred in the refrigerant that has passed through the heating unit, a control device that determines that the refrigerant enclosed in the refrigeration cycle device is insufficient,
In a branch portion where the bypass circuit branches from the pipe, when a gas-liquid two-phase refrigerant flows through the pipe, a gas refrigerant configured to separate the gas refrigerant from the gas-liquid two-phase refrigerant and flow the gas refrigerant to the bypass circuit. An outdoor unit of a refrigeration cycle device, comprising: a liquid separation mechanism.
The outdoor unit of the refrigeration cycle apparatus according to claim 1, wherein in the gas-liquid separation mechanism, the bypass circuit is configured to branch upward from the pipe.
The outdoor unit of the refrigeration cycle apparatus according to claim 2, wherein an inner diameter of the bypass circuit is larger than a reference inner diameter indicating the inner diameter when the flow rate of the gas refrigerant flowing from the pipe into the bypass circuit is zero penetration flow rate. .
4. The outdoor unit of the refrigeration cycle device according to claim 2, wherein, in the gas-liquid separation mechanism, the pipe is disposed downward from the branch portion. 5.
The piping is
A first portion disposed laterally;
A second portion connected to the first portion and disposed downward from the branch portion;
The outdoor unit of the refrigeration cycle apparatus according to claim 4, wherein a center line of the first portion has an offset with respect to a center line of the second portion.
The refrigeration cycle according to any one of claims 2 to 5, wherein the gas-liquid separation mechanism includes a mesh-shaped member configured to capture droplets flowing into the bypass circuit from the branch portion. Equipment outdoor unit.
An outdoor unit according to any one of claims 1 to 6,
A refrigeration cycle device comprising: an indoor unit connected to the outdoor unit.
An air conditioner comprising the refrigeration cycle device according to claim 7.