Control device and refrigeration cycle device

Abstract

To provide a control device and a refrigeration cycle device capable of expanding a control range of a refrigeration cycle circuit while suppressing disproportionation reactions.SOLUTION: A control device 3 executes control of a compressor 4 in a refrigeration cycle circuit where a working medium 20 containing an ethylene-based fluoro-olefin circulates as a refrigerant component in accordance with a result of comparison between a measured value indicating at least one of an internal temperature and an internal pressure of the compressor 4 and at least one of a plurality of threshold values. The plurality of threshold values includes a first threshold value and a second threshold value smaller than the first threshold value. The control device 3 is configured to: cause the compressor 4 to stop when the measured value exceeds the first threshold value; cause the compressor 4 to operate so that a drive frequency changes at a first frequency change rate during a period when the measured value is the second threshold value or less; and, when the measured value exceeds the second threshold value, cause the compressor 4 to operate so that the drive frequency changes at a second frequency change rate different from the first frequency change rate at least one of a case where the drive frequency is increased and a case where the drive frequency is reduced.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a control device and a refrigeration cycle device. [Background technology]

[0002] Conventionally, R410A has been widely used as a working medium (heat medium, refrigerant) for refrigeration cycle devices. However, the global warming potential (GWP) of R410A is as high as 2090. Therefore, from the viewpoint of preventing global warming, research and development of working mediums with smaller GWP has been conducted. Patent Document 1 discloses 1,1,2-trifluoroethylene (HFO1123) as a working medium with a smaller GWP than R410A. Patent Document 2 discloses 1,2-difluoroethylene (HFO1132) as a working medium with a smaller GWP than R410A.

[0003] HFO1123 and HFO1132 have a smaller GWP than R410A, but are therefore less stable than R410A. For example, the generation of radicals may cause disproportionation of HFO1123 or HFO1132, resulting in the conversion of HFO1123 and HFO1132 to other compounds.

[0004] Patent Document 3 discloses a refrigeration system having a refrigerant circuit configured by connecting a compressor, a condenser, a throttling device, and an evaporator with refrigerant piping, and having 1,1,2-trifluoroethylene as the refrigerant circulating through the refrigerant circuit. The refrigeration system disclosed in Patent Document 3 has a first refrigerant sensor provided on the discharge side of the compressor and detecting the temperature and pressure of the refrigerant, and a control unit that controls the compressor based on the detection result of the first refrigerant sensor. The control unit has a disproportionation reaction determination means that determines whether the detection result of the first refrigerant sensor satisfies a preset condition before the occurrence of a disproportionation reaction of the refrigerant, and a compressor speed control means that suppresses the rotation speed of the compressor when the disproportionation reaction determination means determines that the preset condition is satisfied. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 157764 [Patent Document 2] International Publication No. 2012 / 157765 [Patent Document 3] International Publication No. 2015 / 140882 Summary of the Invention [Problem to be solved by the invention]

[0006] The refrigeration device disclosed in Patent Document 3 stops the compressor when it is determined that the refrigerant temperature and the refrigerant pressure are equal to or higher than the first temperature and the first pressure before the disproportionation reaction occurs. However, in order to stop the compressor so as not to cause the disproportionation reaction, it is possible to make the first temperature and the first pressure sufficiently lower than the temperature and the pressure at which the disproportionation reaction occurs, and to advance the timing of stopping the compressor. However, the lower the first temperature and the first pressure are made below the temperature and the pressure at which the disproportionation reaction occurs, the narrower the range of the refrigerant temperature and the refrigerant pressure at which the refrigeration device (refrigeration cycle device) can perform normal operation, that is, the narrower the control range of the refrigeration cycle device. This leads to a decrease in the marketability of the refrigeration cycle device.

[0007] The present disclosure provides a control device and a refrigeration cycle device that enable the suppression of a disproportionation reaction while expanding the control range of a refrigeration cycle circuit. [Means for solving the problem]

[0008] A control device according to one embodiment of the present disclosure is a control device for controlling a compressor of a refrigeration cycle circuit in which a working medium containing an ethylene-based fluoroolefin as a refrigerant component circulates, the working medium containing an ethylene-based fluoroolefin as a refrigerant component, and the control device includes a measurement circuit that outputs a measurement value indicating at least one of an internal temperature or an internal pressure of the compressor, and a control circuit that compares the measurement value from the measurement circuit with at least one of a plurality of thresholds and controls the compressor according to a comparison result. The plurality of thresholds include a first threshold and a second threshold smaller than the first threshold. The control circuit stops the compressor when the measurement value exceeds the first threshold, operates the compressor such that the drive frequency of the compressor changes at a first frequency change rate while the measurement value is equal to or less than the second threshold, and operates the compressor such that the drive frequency changes at a second frequency change rate different from the first frequency change rate in at least one of a case where the drive frequency is increased and a case where the drive frequency is decreased when the measurement value exceeds the second threshold.

[0009] A control device according to one aspect of the present disclosure is a control device for controlling a compressor and an expansion valve of a refrigeration cycle circuit in which a working medium circulates, the working medium including an ethylene-based fluoroolefin as a refrigerant component, the control device including: a measurement circuit for outputting a measurement value indicating at least one of an internal temperature or an internal pressure of the compressor; and a control circuit for comparing the measurement value from the measurement circuit with at least one of a plurality of thresholds and controlling the compressor and the expansion valve according to a comparison result. The plurality of thresholds include a first threshold and a second threshold smaller than the first threshold. The control circuit stops the compressor when the measurement value exceeds the first threshold, operates the expansion valve such that the opening of the expansion valve of the refrigeration cycle circuit changes at a first opening change rate while the measurement value is equal to or less than the second threshold, and operates the expansion valve such that the opening changes at a second opening change rate different from the first opening change rate in at least one of increasing the opening and decreasing the opening when the measurement value exceeds the second threshold.

[0010] A refrigeration cycle device according to an aspect of the present disclosure includes any one of the control devices described above and a refrigeration cycle circuit. Effect of the Invention

[0011] The aspects of the present disclosure enable suppression of disproportionation reactions while expanding the control range of the refrigeration cycle circuit. [Brief description of the drawings]

[0012] [Figure 1] Block diagram of a refrigeration cycle device according to a first embodiment. [Diagram 2] 1 is a schematic diagram of a compressor and a control device of a refrigeration cycle device according to a first embodiment. [Diagram 3] FIG. 1 is an explanatory diagram of control of a compressor by a control circuit of a control device according to a first embodiment; [Figure 4] Block diagram of a refrigeration cycle device according to a second embodiment. [Diagram 5] FIG. 13 is an explanatory diagram of control of a compressor and an expansion valve by a control circuit of a control device according to a second embodiment. [Figure 6] FIG. 4 is an explanatory diagram of a control of a compressor by a control circuit of a control device according to a modified example; [Figure 7] FIG. 4 is an explanatory diagram of a control of a compressor by a control circuit of a control device according to a modified example; [Figure 8] FIG. 2 is an explanatory diagram of control of a compressor and an expansion valve by a control circuit of a control device according to a modified example. [Figure 9] FIG. 2 is an explanatory diagram of control of a compressor and an expansion valve by a control circuit of a control device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [1. Embodiment] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings in some cases. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents (e.g., the shape, dimensions, arrangement, etc. of each component). Positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Each figure described in the following embodiments is a schematic diagram, and the size and thickness ratios of each component in each figure do not necessarily reflect the actual dimensional ratios. Furthermore, the dimensional ratios of each element are not limited to the ratios shown in the drawings.

[0014] In the following description, when it is necessary to distinguish between multiple components, prefixes such as "first" and "second" are added to the names of the components. However, when the components can be distinguished from one another by the symbols added to them, the prefixes such as "first" and "second" may be omitted in consideration of readability of the text.

[0015] In the following description, when it is necessary to distinguish between multiple components, suffixes such as "-1" and "-2" are added to the symbols of the components. However, when it is not necessary to distinguish between multiple components, the suffixes "-1" and "-2" may be omitted in consideration of readability of the text.

[0016] [1.1 First embodiment] [1.1.1 Configuration] 1 is a block diagram of a refrigeration cycle apparatus 1 according to the present embodiment. The refrigeration cycle apparatus 1 constitutes, for example, an air conditioner capable of cooling operation and heating operation. The refrigeration cycle apparatus 1 includes a refrigeration cycle circuit 2 and a control device 3.

[0017] The refrigeration cycle circuit 2 constitutes a flow path through which the working medium 20 (see FIG. 2) circulates. In this embodiment, the working medium 20 contains an ethylene-based fluoroolefin as a refrigerant component. The ethylene-based fluoroolefin may be an ethylene-based fluoroolefin that undergoes a disproportionation reaction. Examples of the ethylene-based fluoroolefin that undergoes a disproportionation reaction include 1,1,2-trifluoroethylene (HFO1123), trans-1,2-difluoroethylene (HFO1132(E)), cis-1,2-difluoroethylene (HFO-1132(Z)), 1,1-difluoroethylene (HFO-1132a), tetrafluoroethylene (CF2=CF2,FO1114), and monofluoroethylene (HFO-1141).

[0018] The working medium 20 may contain a plurality of types of refrigerant components. The working medium 20 may contain an ethylene-based fluoroolefin as a main refrigerant component and a compound other than an ethylene-based fluoroolefin as a secondary refrigerant component. Examples of the secondary refrigerant component include hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), saturated hydrocarbons, carbon dioxide, and the like. Examples of hydrofluorocarbons (HFCs) include difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluorobutane, heptafluorocyclopentane, and the like. Examples of hydrofluoroolefins (HFOs) include monofluoropropene, trifluoropropene, tetrafluoropropene, pentafluoropropene, hexafluorobutene, and the like. Examples of saturated hydrocarbons include ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), methylcyclobutane, and the like.

[0019] The working fluid 20 may further include a disproportionation inhibitor that suppresses the disproportionation reaction of the ethylene-based fluoroolefin. Examples of the disproportionation inhibitor include saturated hydrocarbons or haloalkanes. Examples of saturated hydrocarbons include ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), methylcyclobutane, and the like. In the above examples, n-propane is preferred. Examples of haloalkanes include haloalkanes having 1 or 2 carbon atoms. Examples of haloalkanes having one carbon atom (i.e., halomethanes) include (mono)iodomethane (CH3I), diiodomethane (CH2I2), dibromomethane (CH2Br2), bromomethane (CH3Br), dichloromethane (CH2Cl2), chloroiodomethane (CH2ClI), dibromochloromethane (CHBr2Cl), tetraiodomethane (CI4), carbon tetrabromide (CBr4), bromotrichloromethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CBr3F), fluorodiiodomethane (CHFI2), difluorodiiodomethane (CF2I2), dibromodifluoromethane (CBr2F2), trifluoroiodomethane (CF3I), difluoroiodomethane (CHF2I), and the like. Examples of haloalkanes having 2 carbon atoms (i.e., haloethanes) include 1,1,1-trifluoro-2-iodoethane (CF3CH2I), monoiodoethane (CH3CH2I), monobromoethane (CH3CH2Br), 1,1,1-triiodoethane (CH3CI3), etc. The working medium 20 may contain one or more types of haloalkanes having 1 or 2 carbon atoms. That is, only one type of haloalkane having 1 or 2 carbon atoms may be used, or two or more types may be used in appropriate combination.

[0020] The refrigeration cycle circuit 2 includes a compressor 4, a first heat exchanger 5, an expansion valve 6, a second heat exchanger 7, and a four-way valve 8.

[0021] The refrigeration cycle device 1 includes an outdoor unit 1a and an indoor unit 1b. The outdoor unit 1a includes a control device 3, a compressor 4, a first heat exchanger 5, an expansion valve 6, and a four-way valve 8. The outdoor unit 1a further includes a first blower 5a for promoting heat exchange in the first heat exchanger 5. The indoor unit 1b includes a second heat exchanger 7. The indoor unit 1b further includes a second blower 7a for promoting heat exchange in the second heat exchanger 7.

[0022] In the refrigeration cycle circuit 2, the compressor 4 compresses the working medium 20 to increase the pressure of the working medium 20. The compressor 4 will be described in detail later. The first heat exchanger 5 and the second heat exchanger 7 exchange heat between the working medium 20 circulating through the refrigeration cycle circuit 2 and external air (e.g., outside air or room air). The expansion valve 6 adjusts the pressure (evaporation pressure) of the working medium 20 and the flow rate of the working medium 20. The four-way valve 8 switches the direction of the working medium 20 circulating through the refrigeration cycle circuit 2 between a first direction corresponding to a cooling operation and a second direction corresponding to a heating operation.

[0023] In this embodiment, the first direction is the direction in which the working medium 20 circulates through the refrigeration cycle circuit 2 in the order of the compressor 4, the first heat exchanger 5, the expansion valve 6, and the second heat exchanger 7, as indicated by the solid arrow A1 in Figure 1.

[0024] In cooling operation, the compressor 4 compresses and discharges the gaseous working medium 20, and the gaseous working medium 20 is sent to the first heat exchanger 5 via the four-way valve 8. The first heat exchanger 5 exchanges heat between the outside air and the gaseous working medium 20, and the gaseous working medium 20 condenses and liquefies. The liquid working medium 20 is decompressed by the expansion valve 6 and sent to the second heat exchanger 7. In the second heat exchanger 7, heat exchange is performed between the liquid working medium 20 and the indoor air, and the liquid working medium 20 evaporates and becomes the gaseous working medium 20. The gaseous working medium 20 returns to the compressor 4 via the four-way valve 8. In cooling operation, the first heat exchanger 5 functions as a condenser, and the second heat exchanger 7 functions as an evaporator. Therefore, the indoor unit 1b blows air cooled by heat exchange in the second heat exchanger 7 into the room during cooling.

[0025] In this embodiment, the second direction is the direction in which the working medium 20 circulates through the refrigeration cycle circuit 2, in the order of the compressor 4, the second heat exchanger 7, the expansion valve 6, and the first heat exchanger 5, as indicated by the dashed arrow A2 in Figure 1.

[0026] In heating operation, the compressor 4 compresses and discharges the gaseous working medium 20, and the gaseous working medium 20 is sent to the second heat exchanger 7 through the four-way valve 8. The second heat exchanger 7 exchanges heat between the indoor air and the gaseous working medium 20, and the gaseous working medium 20 condenses and becomes liquefied. The liquid working medium 20 is decompressed by the expansion valve 6 and sent to the first heat exchanger 5. In the first heat exchanger 5, heat exchange is performed between the liquid working medium 20 and the outside air, and the liquid working medium 20 evaporates and becomes the gaseous working medium 20. The gaseous working medium 20 returns to the compressor 4 through the four-way valve 8. In heating operation, the first heat exchanger 5 functions as an evaporator, and the second heat exchanger 7 functions as a condenser. Therefore, the indoor unit 1b blows air warmed by heat exchange in the second heat exchanger 7 into the room during heating.

[0027] The control device 3 controls the compressor 4, the first blower 5a, the expansion valve 6, and the second blower 7a of the refrigeration cycle circuit 2.

[0028] FIG. 2 is a schematic diagram of the compressor 4 and the control device 3.

[0029] The compressor 4 is, for example, a hermetic compressor. The compressor 4 may be of a rotary type, a scroll type, or any other known type. The compressor 4 includes a hermetic container 40, a compression mechanism 41, and an electric motor 42.

[0030] The sealed container 40 forms a flow path for the working medium 20. The sealed container 40 has a suction pipe 401 and a discharge pipe 402. The working medium 20 is sucked into the sealed container 40 from the suction pipe 401, compressed by the compression mechanism 41, and then discharged from the discharge pipe 402 to the outside of the sealed container 40. The inside of the sealed container 40 is filled with the high-temperature and high-pressure working medium 20 and lubricating oil. The bottom of the sealed container 40 forms an oil reservoir that stores a mixture of the working medium 20 and the lubricating oil.

[0031] The compression mechanism 41 is located in the sealed container 40 and compresses the working medium 20. The compression mechanism 41 may have a conventionally known configuration. The compression mechanism 41 has, for example, a cylinder that forms a compression chamber, a rolling piston that is disposed in the compression chamber inside the cylinder, and a crankshaft that is coupled to the rolling piston.

[0032] The electric motor 42 is located inside the sealed container 40 and drives the compression mechanism 41. The electric motor 42 is, for example, a brushless motor (three-phase brushless motor). The electric motor 42 includes, for example, a rotor fixed to a crankshaft of the compression mechanism 41 and a stator provided around the rotor. The stator is configured, for example, by concentrating or dispersing a stator winding (magnet wire, etc.) around a stator core (electromagnetic steel plate, etc.) with an insulating material such as insulating paper interposed therebetween. The stator winding is covered with an insulating material. Examples of the insulating material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid polymer, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), etc.

[0033] The compressor 4 may include an accumulator to prevent liquid compression in the compression chamber of the compression mechanism 41. The accumulator separates the working medium 20 into a gaseous working medium 20 and a liquid working medium 20, and guides only the gaseous working medium 20 from the suction pipe 401 into the inside of the sealed container 40.

[0034] The control device 3 includes a drive circuit 31 , a measurement circuit 32 , and a control circuit 33 .

[0035] The drive circuit 31 drives the electric motor 42 of the compressor 4. The drive circuit 31 supplies drive power to the electric motor 42 based on power from the power source 10. In this embodiment, the power source 10 is an AC power source. The drive circuit 31 supplies drive power to the electric motor 42 based on the AC power from the power source 10. In particular, the drive circuit 31 supplies three-phase AC power as drive power to the electric motor 42. The frequency of the three-phase AC power corresponds to the drive frequency of the compressor 4. The drive frequency of the compressor 4 corresponds to the rotation speed of the compressor 4.

[0036] The drive circuit 31 includes a converter circuit 311 and an inverter circuit 312 .

[0037] The converter circuit 311 converts AC power from the power source 10 into DC power. The converter circuit 311 includes a rectifier circuit 311a and a smoothing circuit 311b. The rectifier circuit 311a is a diode bridge composed of a plurality of diodes D1 to D4. The power source 10 is connected between the input terminals (the connection point of the diodes D1 and D2 and the connection point of the diodes D3 and D4) of the rectifier circuit 311a, and the smoothing circuit 311b is connected between the output terminals (the connection point of the diodes D1 and D3 and the connection point of the diodes D2 and D4) of the rectifier circuit 311a. The smoothing circuit 311b includes a series circuit of an inductor L1 and a capacitor C1, smoothes the voltage between the output terminals of the rectifier circuit 311a, and outputs it as a voltage between both ends of the capacitor C1. The configurations of the rectifier circuit 311a and the smoothing circuit 311b in FIG. 2 are well known, so detailed description thereof will be omitted.

[0038] The inverter circuit 312 supplies three-phase AC power to the motor 42 based on the DC power from the converter circuit 311. The inverter circuit 312 includes a plurality of arms U1, U2, V1, V2, W1, and W2. Each of the plurality of arms U1, U2, V1, V2, W1, and W2 is formed of a semiconductor switching element such as a transistor. The series circuit of the arms U1 and U2 is connected in parallel to the capacitor C1 of the converter circuit 311 to form a U-phase leg. The series circuit of the arms V1 and V2 is connected in parallel to the capacitor C1 of the converter circuit 311 to form a V-phase leg. The series circuit of the arms W1 and W2 is connected in parallel to the capacitor C1 of the converter circuit 311 to form a W-phase leg. The configuration of the inverter circuit 312 in FIG. 2 is well known, so a detailed description thereof will be omitted.

[0039] The measurement circuit 32 outputs a measurement value indicating at least one of the internal temperature and the internal pressure of the compressor 4. In the present embodiment, the measurement circuit 32 measures the internal temperature of the compressor 4, and outputs the measurement value indicating the internal temperature of the compressor 4 to the control circuit 33. The measurement circuit 32 includes, for example, a temperature sensor. The temperature sensor is disposed so as to be able to measure, for example, the temperature of the working medium 20 in the sealed container 40 of the compressor 4, or the temperature of the working medium 20 discharged from the discharge pipe 402 of the compressor 4. The position of the temperature sensor is not particularly limited, and it is only necessary that the measurement circuit 32 can directly or indirectly measure the internal temperature of the compressor 4.

[0040] The control circuit 33 can be realized, for example, by a computer system including at least one processor (microprocessor) and one or more memories.

[0041] The control circuit 33 controls the compressor 4 by controlling the drive circuit 31. More specifically, the control circuit 33 controls switching of a plurality of arms U1, U2, V1, V2, W1, and W2 of the inverter circuit 312 of the drive circuit 31 so that the inverter circuit 312 supplies three-phase AC power to the motor 42 based on the DC power from the smoothing circuit 311b. The switching frequency of the inverter circuit 312 is, for example, 1000 Hz to 5000 Hz. The control circuit 33 controls the frequency of the three-phase AC power to control the drive frequency of the compressor 4, that is, the rotation speed of the compressor 4.

[0042] The control circuit 33 executes a process for suppressing the disproportionation reaction of the working medium 20 circulating through the refrigeration cycle circuit 2, based on a measurement value from the measurement circuit 32 (in this embodiment, the internal temperature of the compressor 4).

[0043] It is believed that the causes of the disproportionation reaction of the working medium 20 are heat and radicals. For example, it is believed that the disproportionation reaction of the working medium 20 progresses when radicals are generated under high temperature and high pressure. From this viewpoint, the control circuit 33 executes control of the compressor 4 based on the measurement value from the measurement circuit 32.

[0044] Fig. 3 is an explanatory diagram of control by the control circuit 33. In this embodiment, the measurement value from the measurement circuit 32 indicates the internal temperature of the compressor 4. Fig. 3 shows the relationship between the internal temperature of the compressor 4 and the control of the compressor 4.

[0045] The control circuit 33 compares the measurement value (internal temperature of the compressor 4) from the measurement circuit 32 with at least one of a plurality of threshold values ​​T11 to T15, and controls the compressor 4 according to the comparison result. In this embodiment, the relationship of the magnitudes of the plurality of threshold values ​​T11 to T15 is threshold value T11>threshold value T12>threshold value T13>threshold value T14>threshold value T15.

[0046] When the internal temperature of the compressor 4 exceeds a threshold value T11, the control circuit 33 stops the compressor 4. The threshold value T11 is set based on the temperature at which a disproportionation reaction may occur.

[0047] The control circuit 33 operates the compressor 4 such that the drive frequency of the compressor 4 changes at a first frequency change rate while the internal temperature of the compressor 4 is equal to or lower than a threshold value T15 that is lower than the threshold value T11. The control circuit 33 increases or decreases the drive frequency of the compressor 4 at the first frequency change rate so that the drive frequency of the compressor 4 becomes a target drive frequency. The first frequency change rate is, for example, 0.3 to 1.0 Hz / s, and is, for example, 0.5 Hz / s.

[0048] The threshold T15 is set based on the temperature at which the treatment for suppressing the disproportionation reaction is started. In this embodiment, the threshold T15 is defined by an upper threshold T15a and a lower threshold T15b that is smaller than the upper threshold T15a. The upper threshold T15a is used when the internal temperature increases. The lower threshold T15b is used when the internal temperature decreases. In other words, the internal temperature exceeding the threshold T15 means that the internal temperature exceeds the upper threshold T15a, and the internal temperature being equal to or lower than the threshold T15 means that the internal temperature is equal to or lower than the lower threshold T15b.

[0049] When the internal temperature exceeds a threshold value T15, the control circuit 33 operates the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate in at least one of increasing the drive frequency and decreasing the drive frequency.

[0050] The control circuit 33 increases or decreases the drive frequency of the compressor 4 at the second frequency change rate so that the drive frequency of the compressor 4 becomes a target drive frequency.

[0051] In this embodiment, when the drive frequency is increased, the control circuit 33 makes the second frequency change rate smaller than the first frequency change rate. In FIG. 3, "second frequency change rate (small)" means a second frequency change rate smaller than the first frequency change rate. As an example, the second frequency change rate is 3.0 Hz / 15 s (= 0.2 Hz / s). That is, when the internal temperature exceeds the threshold value T15, the drive frequency is increased more gently compared to when the internal temperature is equal to or lower than the threshold value T15. Therefore, the drive frequency can be increased so that the internal temperature does not exceed the threshold value T11. This enables the control range of the refrigeration cycle circuit 2 to be expanded while enabling the suppression of the disproportionation reaction.

[0052] When the control circuit 33 reduces the driving frequency, it makes the second frequency change rate larger than the first frequency change rate. In FIG. 3, "second frequency change rate (large)" represents the second frequency change rate larger than the first frequency change rate. As an example, the second frequency change rate is 1.0 Hz / s. That is, when the internal temperature exceeds the threshold T15, the driving frequency is reduced significantly compared to when the internal temperature is equal to or lower than the threshold T15. Therefore, it is possible to reduce the driving frequency quickly so that the internal temperature does not exceed the threshold T11. This enables further suppression of the disproportionation reaction.

[0053] When the internal temperature exceeds a threshold T14 that is greater than the threshold T15 and less than the threshold T11, the control circuit 33 prohibits an increase in the drive frequency. In other words, even if it is necessary to increase the drive frequency of the compressor 4 to set the drive frequency of the compressor 4 to a target drive frequency, the control circuit 33 does not increase the drive frequency. On the other hand, a decrease in the drive frequency is permitted. In this case, the control circuit 33 decreases the drive frequency at a second frequency change rate. In this embodiment, the second frequency change rate is set to be greater than the first frequency change rate.

[0054] When the internal temperature exceeds a threshold T13 that is greater than threshold T14 and less than threshold T11, the control circuit 33 operates the compressor 4 so that the drive frequency is reduced at a fourth frequency change rate. More specifically, when the control circuit 33 reduces the drive frequency of the compressor 4 to a target drive frequency, the control circuit 33 reduces the drive frequency at a fourth frequency change rate. The fourth frequency change rate is not particularly limited. As an example, the fourth frequency change rate is 1.0 Hz / 15 s (= 0.07 Hz / s).

[0055] When the internal temperature exceeds a threshold T12 that is greater than the threshold T13 and less than the threshold T11, the control circuit 33 operates the compressor 4 so that the drive frequency is reduced at a third frequency change rate. More specifically, when the control circuit 33 reduces the drive frequency of the compressor 4 to a target drive frequency, the control circuit 33 reduces the drive frequency at a third frequency change rate. The third frequency change rate is not particularly limited. As an example, the third frequency change rate is 5.0 Hz / 15 s (= 0.33 Hz / s). This allows the drive frequency to be reduced quickly. This makes it possible to further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction.

[0056] As an example, in the case of normal load (e.g., outdoor temperature is 43° C. or lower), the threshold T11 may be 62° C., the threshold T12 may be 60° C., the threshold T13 may be 58° C., the threshold T14 may be 56° C., the upper threshold T15a of the threshold T15 may be 54° C., and the lower threshold T15b of the threshold T15 may be 53° C. In the case of high load (e.g., outdoor temperature exceeds 43° C.), the threshold T11 may be 65° C., the threshold T12 may be 64° C., the threshold T13 may be 63° C., the threshold T14 may be 62° C., the upper threshold T15a of the threshold T15 may be 53° C., and the lower threshold T15b of the threshold T15 may be 52° C.

[0057] [1.1.2 Effects, etc.] The control device 3 described above controls the compressor 4 of the refrigeration cycle circuit 2 in which the working medium 20 circulates. The working medium 20 contains an ethylene-based fluoroolefin as a refrigerant component. The control device 3 includes a measurement circuit 32 that outputs a measurement value indicating at least one of the internal temperature and internal pressure of the compressor 4, and a control circuit 33 that compares the measurement value from the measurement circuit 32 with at least one of a plurality of threshold values ​​T11 to T15 and controls the compressor 4 according to the comparison result. The plurality of threshold values ​​T11 to T15 include a threshold value T11 (first threshold value) and a threshold value T15 (second threshold value) that is smaller than the threshold value T11. The control circuit 33 stops the compressor 4 when the measurement value exceeds the threshold value T11 (first threshold value). The control circuit 33 operates the compressor 4 so that the drive frequency of the compressor 4 changes at a first frequency change rate while the measurement value is equal to or smaller than the threshold value T15 (second threshold value). When the measurement value exceeds the threshold value T15, the control circuit 33 operates the compressor 4 so that the drive frequency is changed at a second frequency change rate different from the first frequency change rate in at least one of increasing and decreasing the drive frequency. This configuration makes it possible to expand the control range of the refrigeration cycle circuit 2 while suppressing the disproportionation reaction.

[0058] In the control device 3, the control circuit 33 makes the second frequency change rate smaller than the first frequency change rate when increasing the drive frequency. This configuration makes it possible to expand the control range of the refrigeration cycle circuit 2 while suppressing the disproportionation reaction.

[0059] In the control device 3, when the drive frequency is decreased, the control circuit 33 makes the second frequency change rate greater than the first frequency change rate. This configuration enables further suppression of the disproportionation reaction.

[0060] In the control device 3, the multiple thresholds T11 to T15 include a fourth threshold (threshold T12) that is greater than the second threshold (threshold T15) and less than the first threshold (threshold T11). When the measurement value exceeds the threshold T12, the control circuit 33 operates the compressor 4 so that the drive frequency decreases at a third frequency change rate. This configuration enables further suppression of the disproportionation reaction.

[0061] In the control device 3, at least one threshold T15 of the multiple thresholds T11 to T15 is defined by an upper threshold T15a and a lower threshold T15b that is smaller than the upper threshold T15a. When the measurement value exceeds at least one threshold T15, it means that the measurement value exceeds the upper threshold T15a of at least one threshold T15. When the measurement value becomes equal to or smaller than at least one threshold T15, it means that the measurement value becomes equal to or smaller than the lower threshold T15b of at least one threshold T15. This configuration can reduce the possibility of frequent switching of control due to fluctuations in the measurement value.

[0062] The above-described refrigeration cycle device 1 includes the control device 3 and the refrigeration cycle circuit 2. This configuration makes it possible to expand the control range of the refrigeration cycle circuit 2 while making it possible to suppress the disproportionation reaction.

[0063] In the refrigeration cycle device 1, the ethylene-based fluoroolefin includes an ethylene-based fluoroolefin in which a disproportionation reaction occurs. This configuration makes it possible to further suppress the disproportionation reaction.

[0064] In the refrigeration cycle device 1, the ethylene-based fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene. This configuration enables further suppression of the disproportionation reaction.

[0065] In the refrigeration cycle apparatus 1, the working medium 20 further contains difluoromethane as a refrigerant component. This configuration enables further suppression of the disproportionation reaction.

[0066] In the refrigeration cycle apparatus 1, the working medium 20 further contains saturated hydrocarbons. This configuration enables further suppression of the disproportionation reaction.

[0067] In the refrigeration cycle device 1, the working fluid 20 contains a haloalkane having 1 or 2 carbon atoms as a disproportionation inhibitor for suppressing the disproportionation reaction of the ethylene-based fluoroolefin. This configuration enables further suppression of the disproportionation reaction.

[0068] In the refrigeration cycle apparatus 1, the saturated hydrocarbons include n-propane. This configuration enables further suppression of the disproportionation reaction.

[0069] [1.2 Second embodiment] [1.2.1 Configuration] 4 is a block diagram of a refrigeration cycle apparatus 1A according to the present embodiment. The refrigeration cycle apparatus 1A constitutes, for example, an air conditioner capable of cooling operation and heating operation. The refrigeration cycle apparatus 1A includes a refrigeration cycle circuit 2 and a control device 3A.

[0070] The control device 3A controls the compressor 4 and the expansion valve 6 of the refrigeration cycle circuit 2. The control device 3A includes a drive circuit 31, a measurement circuit 32, and a control circuit 33, similar to the control device 3 of the first embodiment. However, the operation of the control circuit 33 is different from that of the control device 3.

[0071] The control circuit 33 controls the expansion valve 6 in addition to the compressor 4. More specifically, the control circuit 33 increases or decreases the opening of the expansion valve 6. The opening of the expansion valve 6 is an index of the opening degree of the expansion valve 6, and the larger the opening, the closer the expansion valve 6 is to being fully open, and the smaller the opening, the closer the expansion valve 6 is to being fully closed. For example, the opening of the expansion valve 6 can be changed in increments of 1pls. 1pls corresponds to a value obtained by dividing the range of change in the opening of the expansion valve 6 (for example, the difference between the fully open and fully closed openings of the expansion valve 6) by a predetermined number (for example, 480).

[0072] In the present embodiment as well, the control circuit 33 executes a process for suppressing the disproportionation reaction of the working medium 20 circulating through the refrigeration cycle circuit 2, based on a measurement value from the measurement circuit 32 (in this embodiment, the internal temperature of the compressor 4). The control circuit 33 executes control of the compressor 4 and the expansion valve 6, based on the measurement value from the measurement circuit 32.

[0073] Fig. 5 is an explanatory diagram of the control of the compressor 4 and the expansion valve 6 by the control circuit 33. In this embodiment, the measurement value from the measurement circuit 32 indicates the internal temperature of the compressor 4. Fig. 4 shows the relationship between the internal temperature of the compressor 4 and the control of the expansion valve 6.

[0074] The control circuit 33 compares the measurement value (internal temperature of the compressor 4) from the measurement circuit 32 with at least one of a plurality of threshold values ​​T21 to T25, and controls the compressor 4 and the expansion valve 6 according to the comparison result. In this embodiment, the relationship in magnitude between the plurality of threshold values ​​T21 to T25 is threshold value T21>threshold value T22>threshold value T23>threshold value T24>threshold value T25.

[0075] When the internal temperature of the compressor 4 exceeds a threshold value T21, the control circuit 33 stops the compressor 4. The threshold value T21 is set based on the temperature at which a disproportionation reaction may occur.

[0076] The control circuit 33 operates the expansion valve 6 so that the opening of the expansion valve 6 changes at a first rate of change of opening while the internal temperature of the compressor 4 is equal to or lower than a threshold T25 which is smaller than the threshold T21. For example, the control circuit 33 increases or decreases the opening of the expansion valve 6 at a first rate of change of opening so that the discharge temperature of the refrigerant discharged from the compressor 4 becomes a target temperature. The internal temperature of the compressor 4 indicated by the measurement value from the measurement circuit 32 can be used as the discharge temperature of the refrigerant. The first rate of change of opening is, for example, d×1pls / 60s, where d is the difference between the discharge temperature and the target temperature.

[0077] The threshold T25 is set based on the temperature at which the treatment for suppressing the disproportionation reaction is started. In this embodiment, the threshold T25 is defined by an upper threshold T25a and a lower threshold T25b that is smaller than the upper threshold T25a. The upper threshold T25a is used when the internal temperature increases. The lower threshold T25b is used when the internal temperature decreases. In other words, the internal temperature exceeding the threshold T25 means that the internal temperature exceeds the upper threshold T25a, and the internal temperature being equal to or lower than the threshold T25 means that the internal temperature is equal to or lower than the lower threshold T25b.

[0078] When the internal temperature exceeds the threshold value T25, the control circuit 33 operates the expansion valve 6 so that the opening changes at a second opening change rate different from the first opening change rate in at least one of increasing the opening and decreasing the opening.

[0079] In this embodiment, when decreasing the opening degree, the control circuit 33 operates the expansion valve 6 so that the opening degree changes at a second rate of change of opening that is different from the first rate of change of opening. On the other hand, when increasing the opening degree, the control circuit 33 operates the expansion valve 6 so that the opening degree changes at the first rate of change of opening.

[0080] In this manner, in this embodiment, the rate of change of the opening degree is different between when the opening degree is increased and when it is decreased. The rate of change of the opening degree when the opening degree is increased is set to the first rate of change of the opening degree, and the rate of change of the opening degree when the opening degree is decreased is set to the second rate of change of the opening degree. This is because an increase in the opening degree leads to a decrease in the internal temperature of the compressor 4, whereas a decrease in the opening degree leads to an increase in the internal temperature of the compressor 4. In other words, the control circuit 33 decreases the opening degree of the expansion valve 6 at the second rate of change of the opening degree or increases the opening degree of the expansion valve 6 at the first rate of change of the opening degree so that the discharge temperature of the refrigerant discharged from the compressor 4 becomes the target temperature.

[0081] In this embodiment, when the control circuit 33 decreases the opening degree, the second opening degree change rate is set to be smaller than the first opening degree change rate. As an example, the second opening degree change rate is 1 to 5 pls / 60s. That is, when the internal temperature exceeds the threshold value T25, the opening degree is decreased more gently than when the internal temperature is equal to or lower than the threshold value T25. Therefore, the opening degree can be decreased so that the internal temperature does not exceed the threshold value T21. This enables the control range of the refrigeration cycle circuit 2 to be expanded while enabling the suppression of the disproportionation reaction.

[0082] When the internal temperature exceeds a threshold T24 that is greater than the threshold T25 and less than the threshold T21, the control circuit 33 operates the expansion valve 6 so that the opening is decreased at a fourth opening change rate that is smaller than the second opening change rate when the opening is to be decreased. As an example, the fourth opening change rate is 1pls / 180s (=0.3pls / 60s). That is, when the internal temperature exceeds the threshold T24, the opening is decreased more gently compared to when the internal temperature is equal to or less than the threshold T25. Therefore, the opening can be decreased so that the internal temperature does not exceed the threshold T21. This enables the expansion of the control range of the refrigeration cycle circuit 2 while enabling the suppression of the disproportionation reaction. On the other hand, when the control circuit 33 increases the opening, the control circuit 33 operates the expansion valve 6 so that the opening changes at a first opening change rate.

[0083] When the internal temperature exceeds a threshold T23 that is greater than the threshold T24 and less than the threshold T21, the control circuit 33 operates the expansion valve 6 so that the opening degree increases at the third opening degree change rate. More specifically, when the opening degree of the expansion valve 6 is increased to set the discharge temperature of the refrigerant discharged from the compressor 4 to the target temperature, the control circuit 33 increases the opening degree at the third opening degree change rate. The third opening degree change rate is not particularly limited. As an example, the third opening degree change rate is 2pls / 60s. On the other hand, when the opening degree is decreased, the control circuit 33 prohibits the decrease of the opening degree. That is, even if it is necessary to decrease the opening degree of the expansion valve 6 to set the discharge temperature of the refrigerant discharged from the compressor 4 to the target temperature, the control circuit 33 does not decrease the opening degree. This makes it possible to further suppress the increase in the internal temperature or internal pressure of the compressor 4. This enables further suppression of the disproportionation reaction.

[0084] When the internal temperature exceeds a threshold T22 that is greater than the threshold T23 and less than the threshold T21, the control circuit 33 operates the expansion valve 6 so that the opening is increased at a fifth opening change rate that is greater than the third opening change rate. In this embodiment, the control circuit 33 forcibly increases the opening at the fifth opening change rate. As an example, the fifth opening change rate is 30pls / 30s (=60pls / 60s). This allows for a forced rapid increase in the opening. This can further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction.

[0085] As an example, in the case of normal load (e.g., outdoor temperature is 43° C. or lower), the threshold T21 may be 62° C., the threshold T22 may be 60° C., the threshold T23 may be 58° C., the threshold T24 may be 56° C., the upper threshold T25a of the threshold T25 may be 54° C., and the lower threshold T25b of the threshold T25 may be 53° C. In the case of high load (e.g., outdoor temperature exceeds 43° C.), the threshold T21 may be 65° C., the threshold T22 may be 64° C., the threshold T23 may be 63° C., the threshold T24 may be 62° C., the upper threshold T25a of the threshold T25 may be 53° C., and the lower threshold T25b of the threshold T25 may be 52° C.

[0086] [1.2.2 Effects, etc.] The control device 3A described above controls the compressor 4 and the expansion valve 6 of the refrigeration cycle circuit 2 in which the working medium 20 circulates. The working medium 20 contains an ethylene-based fluoroolefin as a refrigerant component. The control device 3 includes a measurement circuit 32 that outputs a measurement value indicating at least one of the internal temperature and internal pressure of the compressor 4, and a control circuit 33 that compares the measurement value from the measurement circuit 32 with at least one of a plurality of thresholds T21 to T25 and controls the compressor 4 and the expansion valve 6 according to the comparison result. The plurality of thresholds T21 to T25 include a threshold T21 (first threshold) and a threshold T25 (second threshold) that is smaller than the first threshold. The control circuit 33 stops the compressor 4 when the measurement value exceeds the threshold T21 (first threshold). The control circuit 33 operates the expansion valve 6 so that the opening degree of the expansion valve 6 changes at a first opening degree change rate while the measurement value is equal to or smaller than the threshold T25 (second threshold). When the measurement value exceeds the threshold value T25, the control circuit 33 operates the expansion valve 6 so that the opening is increased or decreased at least in one of the two cases, and the opening changes at a second rate of change in opening different from the first rate of change in opening. This configuration makes it possible to expand the control range of the refrigeration cycle circuit 2 while suppressing the disproportionation reaction.

[0087] In the control device 3A, when the opening degree is decreased, the control circuit 33 makes the second rate of change of opening smaller than the first rate of change of opening. This configuration makes it possible to expand the control range of the refrigeration cycle circuit 2 while suppressing the disproportionation reaction.

[0088] In the control device 3A, the multiple thresholds T21 to T25 include a third threshold (threshold T23) that is greater than the second threshold (threshold T25) and less than the first threshold (threshold T21). When the measurement value exceeds the threshold T23, the control circuit 33 operates the expansion valve 6 so that the opening increases at a third opening change rate. This configuration enables further suppression of the disproportionation reaction.

[0089] In the control device 3A, at least one threshold T25 (second threshold) of the multiple thresholds T21 to T25 is defined by an upper threshold T25a and a lower threshold T25b that is smaller than the upper threshold T25a. When the measurement value exceeds at least one threshold T25, it means that the measurement value exceeds the upper threshold T25a of at least one threshold T25. When the measurement value becomes equal to or smaller than at least one threshold T25, it means that the measurement value becomes equal to or smaller than the lower threshold T25b of at least one threshold T25. This configuration can reduce the possibility of frequent switching of control due to fluctuations in the measurement value.

[0090] [2. Modifications] The embodiments of the present disclosure are not limited to the above-mentioned embodiments. The above-mentioned embodiments can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Below, modified examples of the above-mentioned embodiments are listed. The modified examples described below can be applied in appropriate combination.

[0091] In the following, reference will be made to symbols used in the first embodiment even though they are applicable to either the first or second embodiment described above. However, this is merely for the purpose of simplifying the description and is not intended to exclude application to the second embodiment.

[0092] In one modified example, the control circuit 33 may be configured to execute both the control shown in FIG. 3 and the control shown in FIG. 5. That is, the control circuit 33 stops the compressor 4 when the measurement value exceeds a threshold value T11 (first threshold value). The control circuit 33 operates the compressor 4 so that the drive frequency of the compressor 4 changes at a first frequency change rate while the measurement value is equal to or less than a threshold value T15 (second threshold value) that is smaller than the threshold value T11. The control circuit 33 may operate the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate in at least one of increasing the drive frequency and decreasing the drive frequency when the measurement value exceeds the threshold value T15. Furthermore, the control circuit 33 may operate the expansion valve 6 so that the opening degree of the expansion valve 6 changes at a first opening change rate while the measurement value is equal to or less than a threshold value T23 (third threshold value) that is smaller than the threshold value T11 (first threshold value). The control circuit 33 may operate the expansion valve 6 so that when the measured value exceeds the threshold value T23, the opening degree is increased or decreased at least in one case, and the opening degree is changed at a second rate of change in opening degree different from the first rate of change in opening degree. In this case, the threshold value T11 and the threshold value T21 are set to be the same. On the other hand, the threshold values ​​T12, T13, T14, and T15 and the threshold values ​​T22, T23, T24, and T25 do not necessarily have to be set to be the same.

[0093] In one modification, the thresholds other than the threshold T15 among the multiple thresholds T11 to T15 may also be defined by upper and lower thresholds. In particular, it is preferable to define the thresholds included in the range in which the fluctuation of the measurement value from the measurement circuit 32 is large by the upper and lower thresholds. Fig. 6 is an explanatory diagram of the control of the compressor 4 by the control circuit 33 of the control device 3 according to one modification. In Fig. 6, three thresholds T12, T13, and T15 among the multiple thresholds T11 to T15 are defined by upper thresholds T12a, T13a, and T15a, and lower thresholds T12b, T13b, and T15b that are smaller than the upper thresholds T12a, T13a, and T15a, respectively. The internal temperature exceeding the thresholds T12, T13, T15 means that the internal temperature exceeds the upper thresholds T12a, T13a, T15a, and the internal temperature falling below the thresholds T12, T13, T15 means that the internal temperature falls below the lower thresholds T12b, T13b, T15b. This configuration can reduce the possibility of frequent control switching due to fluctuations in the measurement value. The differences between the upper thresholds T12a, T13a, T15a and the lower thresholds T12b, T13b, T15b are not particularly limited, and may be set to, for example, 1°C. However, it is not necessarily necessary to define the thresholds as upper and lower thresholds.

[0094] In one modification, the threshold value for controlling the compressor 4 is not limited to the example of FIG. 3. FIG. 7 is an explanatory diagram of the control of the compressor 4 by the control circuit 33 of the control device 3 according to one modification. In FIG. 7, the threshold values ​​T13 and T14 are not set, unlike FIG. 3. In FIG. 7, the control circuit 33 operates the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate when the internal temperature exceeds the threshold value T15. The control circuit 33 operates the compressor 4 so that the drive frequency decreases at a third frequency change rate when the internal temperature exceeds a threshold value T12 that is greater than the threshold value T15 and less than the threshold value T11. The threshold value T12 is not essential, and the control circuit 33 may operate the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate while the internal temperature exceeds the threshold value T15 but is equal to or less than the threshold value T11.

[0095] In one modified example, the control circuit 33 does not necessarily operate the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate both when the drive frequency is increased and when the drive frequency is decreased. The control circuit 33 may operate the compressor 4 so that the drive frequency changes at a second frequency change rate different from the first frequency change rate at least one of when the drive frequency is increased and when the drive frequency is decreased.

[0096] In one modification, the thresholds for controlling the compressor 4 and the expansion valve 6 are not limited to the example of FIG. 5. FIG. 8 is an explanatory diagram of the control of the compressor 4 and the expansion valve 6 by the control circuit 33 of the control device 3 according to one modification. In FIG. 8, the thresholds T22 and T24 are not set, as compared with FIG. 5. In FIG. 8, when the internal temperature exceeds the threshold T25, the control circuit 33 operates the expansion valve 6 so that the opening decreases at a second opening change rate different from the first opening change rate when the opening is decreased. When the internal temperature exceeds a threshold T23 that is greater than the threshold T25 and less than the threshold T21, the control circuit 33 operates the expansion valve 6 so that the opening increases at a third opening change rate. In addition, the threshold T23 is not essential, and the control circuit 33 may operate the expansion valve 6 so that the opening changes at a second opening change rate that is smaller than the first opening change rate while the internal temperature exceeds the threshold T25 but is equal to or less than the threshold T21.

[0097] FIG. 9 is an explanatory diagram of the control of the compressor 4 and the expansion valve 6 by the control circuit 33 of the control device 3 according to one modification. The control circuit 33 may operate the expansion valve 6 so that the opening changes at a second rate of change of opening different from the first rate of change of opening both when the opening is increased and when the opening is decreased. Here, the control circuit 33 may make the second rate of change of opening smaller than the first rate of change of opening when the opening is decreased, and may make the second rate of change of opening larger than the first rate of change of opening when the opening is increased. In FIG. 9, "second rate of change of opening (small)" means a second rate of change of opening smaller than the first rate of change of opening, and "second rate of change of opening (large)" means a second rate of change of opening larger than the first rate of change of opening. In FIG. 9, when the internal temperature exceeds the threshold T25, the opening is increased more than when the internal temperature is equal to or lower than the threshold T25. Therefore, the opening can be increased quickly so that the internal temperature does not exceed the threshold T21. This enables further suppression of the disproportionation reaction.

[0098] In one modified example, the control circuit 33 does not necessarily operate the expansion valve 6 so that the opening changes at a second rate of change in opening that is different from the first rate of change in both the case of increasing the opening and the case of decreasing the opening. The control circuit 33 only needs to operate the expansion valve 6 so that the opening changes at a second rate of change in opening that is different from the first rate of change in at least one of the case of increasing the opening and the case of decreasing the opening.

[0099] In one modification, the control circuit 33 may further control the first blower 5a in the process for suppressing the disproportionation reaction. That is, the refrigeration cycle circuit 2 includes the first heat exchanger 5 of the outdoor unit 1a and the first blower 5a for promoting heat exchange in the first heat exchanger 5. The multiple thresholds include a fifth threshold smaller than the first threshold, and the control circuit 33 may increase the rotation speed of the first blower 5a when the measurement value exceeds the fifth threshold when the first heat exchanger 5 is made to function as a condenser (that is, when performing cooling operation). This allows the temperature of the working medium 20 to be further reduced in the first heat exchanger 5, making it possible to further suppress the disproportionation reaction. In the example of FIG. 3, the threshold T11 may be used as the first threshold, and any one of the thresholds T12 to T15 may be used as the fifth threshold. In the example of FIG. 5, the threshold T21 may be used as the first threshold, and any one of the thresholds T22 to T25 may be used as the fifth threshold. The fifth threshold may be set separately from the thresholds T12 to T15 and T22 to T25.

[0100] In one modification, the control circuit 33 may further control the second blower 7a in the process for suppressing the disproportionation reaction. That is, the refrigeration cycle circuit 2 includes the second heat exchanger 7 of the indoor unit 1b and the second blower 7a for promoting heat exchange in the second heat exchanger 7. The multiple thresholds include a sixth threshold smaller than the first threshold, and the control circuit 33 may reduce the rotation speed of the second blower 7a when the measurement value exceeds the sixth threshold when the second heat exchanger 7 is made to function as an evaporator (that is, when the cooling operation is performed). When the control circuit 33 executes the process for suppressing the disproportionation reaction, the cooling capacity of the refrigeration cycle device 1 tends to decrease, so that the evaporation temperature, the low pressure temperature, and the temperature of the first heat exchanger 5 can be reduced by reducing the rotation speed of the second blower 7a from the current value. In the example of FIG. 3, the threshold T11 is the first threshold, and any one of the thresholds T12 to T15 may be used as the sixth threshold. 5, threshold T21 is the first threshold, and any one of thresholds T22 to T25 may be used as the sixth threshold. The sixth threshold may be set separately from thresholds T12 to T15 and T22 to T25.

[0101] In one modified example, the third frequency change rate may be greater than the first frequency change rate. This allows the drive frequency to be quickly reduced. This makes it possible to further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction. Referring to FIG. 7, when the control circuit 33 reduces the drive frequency when the measurement value is on a decreasing trend, the second frequency change rate may be greater than the first frequency change rate and less than the third frequency change rate. "The measurement value is on a decreasing trend" includes the measurement value decreasing to be equal to or less than the threshold T12 (fourth threshold). "The measurement value decreases to be equal to or less than the threshold" may mean that the previous measurement value exceeds the threshold, but the current measurement value is equal to or less than the threshold. In this way, when the control circuit 33 reduces the drive frequency when the measurement value is on a decreasing trend, the second frequency change rate may be greater than the first frequency change rate. This allows for a quick reduction in the drive frequency. This makes it possible to further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction.

[0102] In one modified example, the third rate of change of opening may be greater than the first rate of change of opening. This allows for a rapid increase in the opening. This can further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction. Referring to FIG. 9, when the control circuit 33 increases the opening when the measurement value is on a decreasing trend, the second rate of change of opening may be greater than the first rate of change of opening and less than the third rate of change of opening. "The measurement value is on a decreasing trend" includes the measurement value decreasing to be equal to or less than the threshold value T23 (third threshold value). In this way, when the control circuit 33 increases the opening when the measurement value is on a decreasing trend, the second rate of change of opening may be greater than the first rate of change of opening. This allows for a rapid increase in the opening. This can further suppress the rise in the internal temperature or internal pressure of the compressor 4. This allows for further suppression of the disproportionation reaction.

[0103] In one modified example, the measurement circuit 32 may output a measurement value indicating the internal pressure of the compressor 4, instead of the internal temperature of the compressor 4. In this case, the description of the control by the control circuit 33 shown in FIG. 3 and FIG. 5 can be applied by replacing the temperature with the pressure. The measurement circuit 32 may output a measurement value indicating the internal temperature of the compressor 4 and a measurement value indicating the internal pressure of the compressor 4 to the control circuit 33 as the measurement value. The control circuit 33 may switch the control depending on whether one or both of the internal temperature and the internal pressure of the compressor 4 exceed their respective threshold values. For example, the control circuit 33 may stop the compressor 4 when the internal temperature of the compressor 4 exceeds a first threshold value of temperature and the internal pressure of the compressor 4 exceeds a first threshold value of pressure, and the control circuit 33 may stop the compressor 4 when the internal temperature of the compressor 4 exceeds the first threshold value of temperature or the internal pressure of the compressor 4 exceeds the first threshold value of pressure.

[0104] In one modified example, the drive circuit 31 is not limited to the above configuration, but may be a multilevel inverter such as a three-level inverter.

[0105] In one modified example, the refrigeration cycle apparatus 1 is not limited to an air conditioner (so-called room air conditioner (RAC)) configured with one outdoor unit connected to one indoor unit. The refrigeration cycle apparatus 1 may be an air conditioner (so-called package air conditioner (PAC) or building multi air conditioner (VRF)) configured with one or more outdoor units connected to multiple indoor units. Alternatively, the refrigeration cycle apparatus 1 is not limited to an air conditioner, and may be a refrigeration or cooling device such as a refrigerator or a freezer.

[0106] [3. Aspects] As is apparent from the above embodiment and modifications, the present disclosure includes the following aspects.

[0107] [Aspect 1] A control device for controlling a compressor of a refrigeration cycle circuit in which a working medium circulates, The working medium contains an ethylene-based fluoroolefin as a refrigerant component, The control device includes: a measurement circuit that outputs a measurement value indicating at least one of an internal temperature and an internal pressure of the compressor; a control circuit for comparing a measurement value from the measurement circuit with at least one of a plurality of threshold values ​​and controlling the compressor in response to a result of the comparison; Equipped with the plurality of thresholds include a first threshold and a second threshold that is smaller than the first threshold, The control circuit includes: When the measured value exceeds the first threshold, the compressor is stopped. operating the compressor such that a drive frequency of the compressor changes at a first frequency change rate while the measured value is equal to or less than the second threshold value; When the measured value exceeds the second threshold value, the compressor is operated such that the drive frequency changes at a second frequency change rate in at least one of a case where the drive frequency is increased and a case where the drive frequency is decreased. Control device.

[0108] [Aspect 2] When the drive frequency is increased, the control circuit makes the second frequency change rate smaller than the first frequency change rate. The control device of embodiment 1.

[0109] [Aspect 3] When the control circuit reduces the drive frequency, the control circuit makes the second rate of change of frequency greater than the first rate of change of frequency. 3. The control device of embodiment 1 or 2.

[0110] [Aspect 4] the plurality of thresholds further includes a third threshold less than the first threshold, The control circuit includes: operating the expansion valve such that an opening of the expansion valve of the refrigeration cycle circuit changes at a first opening change rate while the measured value is equal to or less than the third threshold value; When the measured value exceeds the third threshold value, the expansion valve is operated so that the opening degree changes at a second rate of change of opening different from the first rate of change of opening in at least one of the cases of increasing the opening degree and decreasing the opening degree. The control device according to any one of aspects 1 to 3.

[0111] [Aspect 5] When increasing the opening degree, the control circuit makes the second rate of change of opening degree larger than the first rate of change of opening degree. The control device of embodiment 4.

[0112] [Aspect 6] When decreasing the opening, the control circuit makes the second rate of change of opening smaller than the first rate of change of opening. The control device of embodiment 4 or 5.

[0113] [Aspect 7] the plurality of thresholds includes a fourth threshold greater than the second threshold and less than the first threshold; The control circuit operates the compressor such that the drive frequency is decreased at a third frequency change rate when the measurement value exceeds the fourth threshold value. The control device according to any one of aspects 1 to 6.

[0114] [Aspect 8] the third rate of change of frequency is greater than the first rate of change of frequency, when the measurement value decreases and becomes equal to or less than the fourth threshold value, the control circuit, in a case where the drive frequency is decreased, makes the second frequency change rate larger than the first frequency change rate and smaller than the third frequency change rate. The control device of embodiment 7.

[0115] [Aspect 9] At least one of the plurality of thresholds is defined by an upper threshold and a lower threshold that is smaller than the upper threshold, the measurement value exceeding the at least one threshold value means that the measurement value exceeds an upper threshold value of the at least one threshold value; The measurement value being equal to or less than the at least one threshold value means that the measurement value is equal to or less than a lower threshold value of the at least one threshold value. The control device according to any one of aspects 1 to 8.

[0116] [Aspect 10] The refrigeration cycle circuit includes a heat exchanger of an indoor unit and a blower for promoting heat exchange in the heat exchanger, the plurality of thresholds includes a fifth threshold that is smaller than the first threshold; The control circuit increases a rotation speed of the blower when the measurement value exceeds the fifth threshold value in a case where the heat exchanger functions as a condenser. The control device according to any one of aspects 1 to 9.

[0117] [Aspect 11] The refrigeration cycle circuit includes a heat exchanger of an outdoor unit and a blower for promoting heat exchange in the heat exchanger, the plurality of thresholds includes a sixth threshold that is smaller than the first threshold; The control circuit reduces a rotation speed of the blower when the measurement value exceeds the sixth threshold value in the case where the heat exchanger functions as an evaporator. The control device according to any one of aspects 1 to 10.

[0118] [Aspect 12] A control device for controlling a compressor and an expansion valve of a refrigeration cycle circuit in which a working medium circulates, The working medium contains an ethylene-based fluoroolefin as a refrigerant component, The control device includes: a measurement circuit that outputs a measurement value indicating at least one of an internal temperature and an internal pressure of the compressor; a control circuit that compares a measurement value from the measurement circuit with at least one of a plurality of threshold values ​​and controls the compressor and the expansion valve in accordance with a result of the comparison; Equipped with the plurality of thresholds include a first threshold and a second threshold that is smaller than the first threshold, The control circuit includes: When the measured value exceeds the first threshold, the compressor is stopped. operating the expansion valve such that the opening of the expansion valve changes at a first opening change rate while the measured value is equal to or less than the second threshold value; When the measured value exceeds the second threshold value, the expansion valve is operated so that the opening degree changes at a second rate of change of opening different from the first rate of change of opening in at least one of the cases of increasing the opening degree and decreasing the opening degree. Control device.

[0119] [Aspect 13] When increasing the opening degree, the control circuit makes the second rate of change of opening degree larger than the first rate of change of opening degree. The control device of embodiment 12.

[0120] [Aspect 14] When decreasing the opening, the control circuit makes the second rate of change of opening smaller than the first rate of change of opening. The control device of embodiment 12 or 13.

[0121] [Aspect 15] the plurality of thresholds includes a third threshold that is greater than the second threshold and less than the first threshold; When the measurement value exceeds the third threshold value, the control circuit operates the expansion valve so that the opening degree increases at a third opening degree change rate. The control device according to any one of aspects 12 to 14.

[0122] [Aspect 16] The third rate of change of opening degree is greater than the first rate of change of opening degree, when the measurement value decreases and becomes equal to or less than the third threshold value, when increasing the opening, the control circuit makes the second rate of change of opening larger than the first rate of change of opening and smaller than the third rate of change of opening. The control device of embodiment 15.

[0123] [Aspect 17] At least one of the plurality of thresholds is defined by an upper threshold and a lower threshold that is smaller than the upper threshold, the measurement value exceeding the at least one threshold value means that the measurement value exceeds an upper threshold value of the at least one threshold value; The measurement value being equal to or less than the at least one threshold value means that the measurement value is equal to or less than a lower threshold value of the at least one threshold value. The control device according to any one of aspects 12 to 16.

[0124] [Aspect 18] A control device according to any one of aspects 1 to 17; The refrigeration cycle circuit; Equipped with Refrigeration cycle equipment.

[0125] [Aspect 19] The ethylene-based fluoroolefin includes an ethylene-based fluoroolefin that undergoes a disproportionation reaction. The refrigeration cycle apparatus of embodiment 18.

[0126] [Aspect 20] The ethylenic fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene; 20. The refrigeration cycle apparatus of aspect 18 or 19.

[0127] [Aspect 21] The working medium further contains difluoromethane as the refrigerant component. The refrigeration cycle device according to any one of aspects 18 to 20.

[0128] [Aspect 22] The working medium further comprises a saturated hydrocarbon. The refrigeration cycle apparatus according to any one of aspects 18 to 21.

[0129] [Aspect 23] The working fluid contains a haloalkane having 1 or 2 carbon atoms as a disproportionation inhibitor for suppressing the disproportionation reaction of the ethylenic fluoroolefin. The refrigeration cycle device according to any one of aspects 18 to 22.

[0130] [Aspect 24] The saturated hydrocarbons include n-propane. A refrigeration cycle device of embodiment 22.

[0131] Aspects 2 to 11, 13 to 17, and 19 to 24 are optional elements and are not essential. [Industrial Applicability]

[0132] The present disclosure is applicable to a control device and a refrigeration cycle device. Specifically, the present disclosure is applicable to a control device for a refrigeration cycle circuit in which a working medium contains an ethylene-based fluoroolefin as a refrigerant component, and a refrigeration cycle device including the refrigeration cycle circuit and the control device. [Explanation of symbols]

[0133] 1,1A Refrigeration cycle device 2 Refrigeration cycle circuit 3,3A Control Device 32 Measurement circuit 33 Control circuit 4. Compressor 6 Expansion valve 7 Second heat exchanger (heat exchanger) 7a 2nd blower (blower)

Claims

1. A control device for controlling a compressor of a refrigeration cycle circuit in which a working medium containing an ethylene-based fluoroolefin as a refrigerant component circulates, comprising: The working medium contains an ethylene-based fluoroolefin as a refrigerant component, The control device includes: a measurement circuit that outputs a measurement value indicating at least one of an internal temperature and an internal pressure of the compressor; a control circuit for comparing a measurement value from the measurement circuit with at least one of a plurality of threshold values ​​and controlling the compressor in response to a result of the comparison; Equipped with the plurality of thresholds include a first threshold and a second threshold that is smaller than the first threshold, The control circuit includes: When the measured value exceeds the first threshold value, the compressor is stopped. operating the compressor such that a drive frequency of the compressor changes at a first frequency change rate while the measured value is equal to or less than the second threshold value; operating the compressor such that the drive frequency changes at a second frequency change rate different from the first frequency change rate in at least one of a case where the drive frequency is increased and a case where the drive frequency is decreased when the measured value exceeds the second threshold value; Control device.

2. the control circuit, when increasing the drive frequency, makes the second rate of change of frequency smaller than the first rate of change of frequency. The control device of claim 1.

3. When the control circuit reduces the drive frequency, the control circuit makes the second rate of change of frequency greater than the first rate of change of frequency. The control device of claim 1.

4. the plurality of thresholds further includes a third threshold less than the first threshold, The control circuit includes: operating the expansion valve such that an opening of the expansion valve of the refrigeration cycle circuit changes at a first opening change rate while the measured value is equal to or less than the third threshold value; When the measured value exceeds the third threshold value, the expansion valve is operated so that the opening degree changes at a second rate of change of opening different from the first rate of change of opening in at least one of the cases of increasing the opening degree and decreasing the opening degree. The control device of claim 1.

5. When increasing the opening degree, the control circuit makes the second rate of change of opening degree larger than the first rate of change of opening degree. The control device of claim 4.

6. When decreasing the opening degree, the control circuit makes the second rate of change of opening degree smaller than the first rate of change of opening degree. The control device of claim 4.

7. the plurality of thresholds includes a fourth threshold greater than the second threshold and less than the first threshold; The control circuit operates the compressor such that the drive frequency is reduced at a third frequency change rate when the measured value exceeds the fourth threshold value. The control device of claim 1.

8. the third rate of change of frequency is greater than the first rate of change of frequency, when the measurement value decreases and becomes equal to or less than the fourth threshold value, the control circuit, in a case of decreasing the drive frequency, sets the second frequency change rate to be greater than the first frequency change rate and smaller than the third frequency change rate. The control device of claim 7.

9. At least one of the plurality of thresholds is defined by an upper threshold and a lower threshold that is smaller than the upper threshold, the measurement value exceeding the at least one threshold value means that the measurement value exceeds an upper threshold value of the at least one threshold value; The measurement value being equal to or less than the at least one threshold value means that the measurement value is equal to or less than a lower threshold value of the at least one threshold value. The control device of claim 1.

10. The refrigeration cycle circuit includes a heat exchanger of an outdoor unit and a blower for promoting heat exchange in the heat exchanger, the plurality of thresholds includes a fifth threshold that is smaller than the first threshold; the control circuit increases a rotation speed of the blower when the measurement value exceeds the fifth threshold value in a case where the heat exchanger functions as a condenser. The control device of claim 1.

11. The refrigeration cycle circuit includes a heat exchanger of an indoor unit and a blower for promoting heat exchange in the heat exchanger, the plurality of thresholds includes a sixth threshold that is smaller than the first threshold; The control circuit reduces a rotation speed of the blower when the measurement value exceeds the sixth threshold value in a case where the heat exchanger functions as an evaporator. The control device of claim 1.

12. A control device for controlling a compressor and an expansion valve of a refrigeration cycle circuit in which a working medium circulates, The working medium contains an ethylene-based fluoroolefin as a refrigerant component, The control device includes: a measurement circuit that outputs a measurement value indicating at least one of an internal temperature and an internal pressure of the compressor; a control circuit that compares a measurement value from the measurement circuit with at least one of a plurality of threshold values ​​and controls the compressor and the expansion valve in accordance with a result of the comparison; Equipped with the plurality of thresholds include a first threshold and a second threshold that is smaller than the first threshold, The control circuit includes: When the measured value exceeds the first threshold value, the compressor is stopped. operating the expansion valve such that the opening of the expansion valve changes at a first opening change rate while the measurement value is equal to or less than the second threshold value; When the measured value exceeds the second threshold value, the expansion valve is operated so that the opening degree changes at a second rate of change of opening different from the first rate of change of opening in at least one of the cases of increasing the opening degree and decreasing the opening degree. Control device.

13. A control device according to claim 1 or 12; The refrigeration cycle circuit; Equipped with Refrigeration cycle equipment.

14. The ethylene-based fluoroolefin includes an ethylene-based fluoroolefin that undergoes a disproportionation reaction. The refrigeration cycle apparatus of claim 13.

15. The ethylenic fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene; The refrigeration cycle apparatus of claim 13.

Images