Refrigeration cycle device

Abstract

Provided is a refrigeration cycle device capable of suppressing a disproportionation reaction of a working medium without compromising the comfort of a user. This refrigeration cycle device (1) is provided with an outdoor unit (30) that includes a compressor (31), and a plurality of indoor units (10) that have expansion valves (15), in which a working medium containing an ethylene-based fluoroolefin is used as a refrigerant, and is provided with a control unit (70) that controls the outdoor unit (30) and the indoor units (10) so as to control the outdoor unit (30) and the indoor units (10). When some of the plurality of indoor units (10) are operated and the discharge temperature (T) of the compressor (31) is equal to or greater than a predetermined temperature (T1), the control unit (70) opens the expansion valve (15) of at least one of the indoor units (10) that are stopped in operation.

Description

Technical Field

[0001] The present invention relates to a refrigeration cycle device. Background Art

[0002] Patent Document 1 discloses a refrigeration cycle device using a thermochemically unstable refrigerant. When the temperature of the working medium discharged from the compressor transiently shifts to a region above a predetermined value, the refrigeration cycle device reduces the temperature of the working medium discharged from the compressor by reducing the drive speed of the compressor.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2020 / 039707 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The present invention provides a refrigeration cycle device capable of suppressing the disproportionation reaction of a working medium without impairing the comfort of a user.

[0008] Technical solutions to solve problems

[0009] This specification includes the entire contents of Japanese Patent Application No. 2022-089807 filed on June 1, 2022.

[0010] The refrigeration cycle device in the present invention includes an outdoor unit and multiple indoor units, the outdoor unit includes a compressor, and the multiple indoor units have an expansion valve, wherein a working medium containing ethylene fluoroolefin is used as a refrigerant. The refrigeration cycle device includes a control unit, and the control unit opens the expansion valve of at least one of the indoor units that is stopped when some of the multiple indoor units are operating and the discharge temperature of the compressor is above a specified temperature.

[0011] Effects of the Invention

[0012] The refrigeration cycle device of the present invention can suppress the disproportionation reaction of the working medium without impairing the comfort of the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing the overall configuration of the refrigeration cycle device in Embodiment 1.

[0014] Figure 2 It is a refrigeration cycle diagram of a refrigeration cycle device.

[0015] Figure 3 It is a block diagram of a refrigeration cycle device.

[0016] Figure 4 This is a flowchart showing the operation of the refrigeration cycle device. DETAILED DESCRIPTION

[0017] (Insights, etc. that form the basis of this disclosure)

[0018] When the inventors thought of the present invention, the technology of refrigeration cycle device required the use of refrigerant with low global warming potential (GWP) which is unlikely to contribute to climate change as working medium. Therefore, in the industry, the refrigerant with low GWP is highly reactive and unstable, and a technology is proposed to stably use unstable refrigerant by reducing the temperature of the working medium by reducing the driving speed of the compressor. Under such circumstances, the inventors found that if the driving speed of the compressor is reduced, it will affect the operating performance of the indoor unit in operation, so there is a problem of damaging the comfort of the user. In order to solve this problem, the subject of the present invention is formed.

[0019] Therefore, the present invention provides a refrigeration cycle device capable of suppressing the disproportionation reaction of the working medium without impairing the comfort of the user.

[0020] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. However, there are cases where more detailed descriptions than necessary are omitted. For example, detailed descriptions of already known matters or repeated descriptions of substantially the same structures may be omitted.

[0021] In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present invention, and are not intended to limit the subject matter described in the claims.

[0022] (Implementation Method 1)

[0023] [1-1. Structure]

[0024] [1-1-1. Overall structure of refrigeration cycle device]

[0025] Figure 1 1 is a diagram schematically showing the overall structure of a refrigeration cycle device 1 according to Embodiment 1. The refrigeration cycle device 1 includes an indoor unit 10 and an outdoor unit 30. The indoor unit 10 is a device disposed indoors in a building such as an office building or a house or a mobile body such as a ship, and performs air conditioning on the indoor space. The outdoor unit 30 is a device mainly disposed outdoors, and a working medium is supplied to the indoor unit 10 via a gas pipe 20 and a liquid pipe 40.

[0026] In the present embodiment, the refrigeration cycle device 1 is constituted by connecting four indoor units 10 to one outdoor unit 30. In addition, the refrigeration cycle device 1 is provided with an operating unit (not shown) corresponding to each indoor unit 10 in the room, and the user sets the set temperature and the like of the air-conditioning operation of the corresponding indoor unit 10 via the operating unit. Hereinafter, the air-conditioning operation including the cooling operation and the heating operation of the indoor unit 10 will be referred to as simply operation. In addition, in the present invention, the number of indoor units 10 constituting one refrigeration cycle device 1 is not limited to four. In addition, in Figure 1 2 shows a structure in which three refrigeration cycle devices 1 independently perform air conditioning on the first floor F1, the second floor F2, and the third floor F3 of the building B, but for the sake of convenience, one refrigeration cycle device 1 will be described below.

[0027] [1-1-2. Configuration of Refrigeration Cycle]

[0028] The refrigeration cycle device 1 uses a working medium containing ethylene fluoroolefin in the refrigeration cycle. Ethylene fluoroolefin has a characteristic that there are many fluoroolefins with low GWP. On the other hand, it is known that ethylene fluoroolefin is exposed to a discharge phenomenon under high temperature and high pressure, thereby causing a disproportionation reaction. Due to the disproportionation reaction, a sharp pressure rise in the refrigeration cycle may occur. The details of the working medium will be described later.

[0029] Figure 2 Refrigeration cycle diagram of refrigeration cycle device 1. Figure 2 As shown, four indoor units 10 are connected in parallel to an outdoor unit 30 via a gas pipe 20 and a liquid pipe 40. Each indoor unit 10 has an indoor heat exchanger 11, an indoor fan 13, and an indoor expansion valve 15. The indoor heat exchanger 11 is, for example, a fin-tube type heat exchanger, which exchanges heat between the working medium flowing inside and the outside air. The indoor fan 13 is, for example, a centrifugal fan, which is connected to the output shaft of an indoor fan motor 13a, which is an electronically controllable motor, and is driven to rotate by the indoor fan motor 13a. The indoor fan 13 draws indoor air into the indoor unit 10 by rotating, and blows it into the room through the indoor heat exchanger 11. The indoor expansion valve (expansion valve) 15 is a valve whose opening and opening degree can be changed by electronic control. The indoor expansion valve 15 allows the working medium to flow by opening, and cuts off the flow of the working medium by closing. In addition, by changing the opening degree of the indoor expansion valve 15, the flow rate of the working medium flowing in each indoor heat exchanger 11 and the magnitude of the decompression of the working medium in the indoor expansion valve 15 are changed.

[0030] The outdoor unit 30 has a compressor 31, a four-way valve 33, an outdoor heat exchanger 35, an outdoor fan 37 and an outdoor expansion valve 39. The compressor 31 is, for example, a scroll compressor, which sucks in, compresses and discharges a gaseous working medium. A working medium temperature sensor 32 is installed near the discharge port of the compressor 31. The working medium temperature sensor 32 measures the temperature of the working medium discharged by the compressor 31, that is, the discharge temperature T. The four-way valve 33 is a device connected to the discharge side of the compressor 31, the suction side of the compressor 31, the outdoor heat exchanger 35 and the gas pipe 20, and can switch the flow path of the working medium by electronic control. By switching the flow path of the working medium by the four-way valve 33, the indoor heat exchanger 11 is switched to function as an evaporator or as a condenser. Thus, the indoor unit 10 is switched to perform cooling operation or heating operation.

[0031] The outdoor heat exchanger 35 is, for example, a fin-tube heat exchanger, and performs heat exchange between the working medium flowing inside and the outside air. The outdoor fan 37 is, for example, an axial flow fan, connected to the output shaft of an outdoor fan motor 37a, which is an electronically controllable motor, and is driven to rotate by the outdoor fan motor 37a. The outdoor fan 37 draws outside air into the interior of the outdoor unit 30 by rotating, and blows the drawn outside air to the outside of the outdoor unit 30 through the outdoor heat exchanger 35. The outdoor expansion valve 39 is, for example, a valve whose opening can be changed by electronic control, and reduces the pressure of the working medium passing through.

[0032] The gas pipe 20 is a refrigerant pipe that connects the four-way valve 33 with the indoor expansion valve 15 of each indoor unit 10. The working medium flowing inside the gas pipe 20 is mainly in a gas state. The liquid pipe 40 is a refrigerant pipe that connects the outdoor expansion valve 39 with the indoor heat exchanger 11 of each indoor unit 10. The working medium flowing inside the liquid pipe 40 is mainly in a liquid state.

[0033] [1-1-3. Structure of control system]

[0034] Figure 3 1 is a block diagram showing the structure of the control system of the refrigeration cycle device 1. In addition, since the structures of the four indoor units 10 are the same, Figure 3 Only the detailed structure of one indoor unit 10 is described, and the detailed structures of the three indoor units 10 are omitted.

[0035] The indoor unit 10 includes a room temperature sensor 12, an indoor communication unit 14, and a human sensor 16. The room temperature sensor 12 is a sensor that measures the room temperature at a predetermined sampling rate. The indoor communication unit 14 is composed of communication hardware such as a connector and a communication line in accordance with a predetermined communication standard, and communicates with the outdoor unit 30 via a control wiring. The human sensor 16 is, for example, an infrared sensor that senses a person in the space where the indoor unit 10 is installed.

[0036] The outdoor unit 30 includes an outdoor communication unit 34 and a control unit 70. The outdoor communication unit 34 is composed of communication hardware such as a connector and a communication line in accordance with a predetermined communication standard, and communicates with the indoor communication unit 14 via a control wiring.

[0037] The control unit 70 controls the operation of each unit of the refrigeration cycle device 1. The control unit 70 includes an outdoor unit memory 71, an outdoor unit processor 73, and an outdoor unit interface 75.

[0038] The outdoor unit memory 71 is a memory for storing programs and data. The outdoor unit memory 71 stores various control programs and data processed by the outdoor unit processor 73. The outdoor unit memory 71 has a non-volatile storage area. In addition, the outdoor unit memory 71 may also include a volatile storage area to constitute a working area of ​​the outdoor unit processor 73.

[0039] The outdoor unit processor 73 is a processor such as a CPU or an MPU. The outdoor unit processor 73 reads and executes a control program stored in the outdoor unit memory 71 to function as a device control unit 73a and a determination unit 73b.

[0040] The outdoor unit interface 75 is an interface including communication hardware such as a connector and a communication line in accordance with a prescribed communication standard. The outdoor unit interface 75 communicates with the outdoor communication unit 34, the compressor 31, the four-way valve 33, the outdoor fan motor 37a, the outdoor expansion valve 39 and the working medium temperature sensor 32.

[0041] The device control unit 73a receives the operation of the user on the operating unit (not shown) provided indoors as a signal, and controls each device of the refrigeration cycle device 1 according to the received signal, thereby performing operation. The device control unit 73a controls each part of the outdoor unit 30 such as the outdoor communication unit 34, the compressor 31, the four-way valve 33, the outdoor fan motor 37a, and the outdoor expansion valve 39 via the outdoor unit interface 75. In addition, the device control unit 73a controls each part of the indoor unit 10 such as the indoor fan motor 13a and the indoor expansion valve 15 via the outdoor communication unit 34 and the indoor communication unit 14, so that the four indoor units 10 are operated individually or stopped. In addition, the state where the indoor unit 10 stops operating includes the state where the indoor unit 10 performs thermal cut-off operation. Thermal cut-off operation is an operation performed when the judgment unit 73b described later judges that the room temperature data measured by the room temperature sensor 12 is consistent with the set temperature set by the user. When the indoor unit 10 in normal operation is transferred to the thermal cut-off operation, the indoor expansion valve 15 of the indoor unit 10 is closed to prevent the room temperature from changing excessively.

[0042] The determination unit 73b receives the measurement data of the discharge temperature T from the working medium temperature sensor 32. In addition, the determination unit 73b receives the data of the room temperature measured by the room temperature sensor 12 and the data of the human sensor 16 via the outdoor communication unit 34 and the indoor communication unit 14. As described later, the determination unit 73b performs various determinations based on the various data received, and changes the control of each device by the device control unit 73a based on the results of the determination.

[0043] [1-1-4. Working medium]

[0044] The refrigerant used in the refrigeration cycle device 1 is a working medium containing ethylene-based fluoroolefins. Ethylene-based fluoroolefins include, for example, any one or more of 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, HFO1114), and monofluoroethylene (HFO-1141).

[0045] The working medium may also contain two or more refrigerant components. That is, it may contain an ethylene fluoroolefin selected from the above examples (e.g., 1,1,2-trifluoroethylene) and a second refrigerant component. As the second refrigerant component, one or more refrigerants selected from hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), saturated hydrocarbons, carbon dioxide or other refrigerants may be cited. As the hydrofluorocarbon, for example, difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, heptafluorocyclopentane may be cited. As the hydrofluoroolefin, for example, monofluoropropylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene and hexafluorobutene are included. As saturated hydrocarbons, for example, ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and methylcyclobutane can be listed, but other hydrocarbons can also be used. The second refrigerant component can include multiple components. That is, the second refrigerant component can also include two or more refrigerant components selected from hydrofluorocarbons, hydrofluoroolefins, saturated hydrocarbons, carbon dioxide, and other refrigerants.

[0046] The working medium used as a refrigerant in the refrigeration cycle device 1 may also contain a disproportionation inhibitor in addition to the refrigerant components. The disproportionation inhibitor is, for example, a saturated hydrocarbon. The working medium may also contain a disproportionation inhibitor composed of one or more components. Saturated hydrocarbons used as disproportionation inhibitors include ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and methylcyclobutane, but other saturated hydrocarbons may also be used. As a particularly preferred disproportionation inhibitor, n-propane can be listed.

[0047] The disproportionation inhibitor may be, for example, a halogenated alkane having 1 or 2 carbon atoms. Examples of the halogenated alkane having 1 carbon atom, i.e., methyl halides, used as the disproportionation inhibitor include (mono) methyl iodide (CH3I), dimethyl iodide (CH2I2), dimethyl bromide (CH2Br2), methyl bromide (CH3Br), dichloromethane (CH2Cl2), chloroiodomethane (CH2ClI), dibromochloromethane (CHBr2Cl), tetraiodomethane (CI4), carbon tetrabromide (CBr4), bromotrichloromethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CBr3F), diiodofluoromethane (CHFI2), difluoroiodomethane (CHF2I), difluorodiiodomethane (CF2I2), dibromodifluoromethane (CBr2F2), and trifluoroiodomethane (CF3I), but other methyl halides may also be used. Examples of halogenated alkanes having two carbon atoms, i.e., halogenated ethanes, used as the disproportionation inhibitor include 1,1,1-trifluoro-2-iodoethane (CF3CH2I), monoiodoethane (CH3CH2I), monobromoethane (CH3CH2Br), and 1,1,1-triiodoethane (CH3CI3).

[0048] The working medium may contain a plurality of disproportionation inhibitors selected from the above-mentioned saturated hydrocarbons and the above-mentioned halogenated alkanes. In addition, the working medium may contain one saturated hydrocarbon, or may be a working medium containing two or more saturated hydrocarbons. In addition, the working medium may contain one halogenated alkanes, or may be a working medium containing two or more halogenated alkanes.

[0049] A preferred example of the working medium is a mixture containing 1,1,2-trifluoroethylene and n-propane. The working medium may contain the second refrigerant component described above, or may contain other components.

[0050] Each of the above working media may contain inevitable impurities, such as various additives including stabilizers added for the purpose of stabilization during transportation and storage, the remainder or by-products of synthetic raw materials of refrigerant components, and substances mixed for other reasons.

[0051] The mass ratio of 1,1,2-trifluoroethylene to n-propane contained in the working medium can be changed appropriately. The capacity of the refrigeration cycle is related to the mass ratio of the refrigerant components contained in the working medium. Therefore, in order to maintain the capacity of the refrigeration cycle, n-propane as a disproportionation inhibitor is preferably configured to contain only 40% by mass or less in the working medium.

[0052] [1-2. Action]

[0053] Hereinafter, the operation and effect of the refrigeration cycle device 1 configured as described above will be described.

[0054] The prescribed temperature T1 used in the following description is determined, for example, based on the heat resistance of the insulating paper inserted between the electromagnetic wire and the electromagnetic steel sheet that generate a magnetic field by energizing the stator of the motor constituting the compressor 31. For example, when the heat resistance class of the insulating paper specified in JIS C4003 is heat resistance class B, the heat resistance temperature is 130°C. If the insulating paper is placed under a temperature condition higher than the heat resistance temperature, the insulation between the electromagnetic wire and the electromagnetic steel sheet is destroyed, and the possibility of a discharge phenomenon that causes a disproportionation reaction increases. The insulating paper is placed under a temperature condition substantially the same as the discharge temperature T, so the refrigeration cycle device 1 changes its operation depending on whether the measured value of the discharge temperature T is above the prescribed temperature T1.

[0055] In the present embodiment, insulating paper of heat-resistant grade E specified in JIS C4003 is used, and its heat-resistant temperature is 120°C. The specified temperature T1 is 115°C with a safety margin of about 5K added to the heat-resistant temperature. In addition, when the temperature of the working medium is above 150°C, the risk of the occurrence of the disproportionation reaction becomes higher regardless of the heat-resistant temperature of the insulating paper. Therefore, even when using insulating paper with a heat-resistant temperature of 150°C or above, the specified temperature T1 is set to a temperature with a safety margin added to 150°C. That is, the specified temperature T1 is set based on the lower temperature of the temperature at which the risk of the occurrence of the discharge phenomenon increases and the temperature at which the risk of the occurrence of the disproportionation reaction caused by the high temperature itself increases.

[0056] Figure 4 1 is a flow chart of the refrigeration cycle device 1, which shows the operation of the refrigeration cycle device 1. Figure 4 The following description will take as an example a case where, at the start time of the flowchart, a plurality of the four indoor units 10 of the refrigeration cycle device 1 are in operation.

[0057] In this state, the device control unit 73a operates the compressor 31 to circulate the working medium in the refrigeration cycle. In addition, the device control unit 73a closes the indoor expansion valve 15 of the indoor unit 10 that is not in operation, and opens the indoor expansion valve 15 of the indoor unit 10 that is in operation. As a result, the working medium that circulates by driving the compressor 31 does not flow to the indoor unit 10 that is not in operation, but only flows to the indoor unit 10 that is in operation.

[0058] In addition, the device control unit 73a controls the indoor expansion valve 15 so that the opening degree of the indoor expansion valve 15 provided in the operating indoor unit 10 becomes larger in approximately proportion to the condensing capacity or evaporating capacity required of each indoor unit 10. The larger the difference between the set temperature and the room temperature and the rotation speed of the indoor fan 13, the larger the condensing capacity and evaporating capacity required of each indoor unit 10.

[0059] In addition, the device control unit 73a increases the opening of the indoor expansion valve 15 of each operating indoor unit 10 in order from the indoor unit 10 having the largest pressure loss dP in the working medium from the compressor 31 to the indoor unit 10. Thus, the opening of the indoor expansion valve 15 per unit condensing capacity or evaporating capacity of the indoor unit 10 increases in order from the indoor unit 10 having the largest pressure loss dP. The pressure loss dP mainly depends on the installation conditions of the refrigeration cycle device 1, such as the length of the refrigerant piping from the compressor 31 to the indoor unit 10, the thickness of the refrigerant piping, the number and curvature of the bends of the refrigerant piping, and the height of the indoor unit 10 relative to the compressor 31.

[0060] The device control unit 73a may control the indoor expansion valve 15, for example, starting from the indoor unit 10 having the longest refrigerant pipe between the outdoor unit 30 and each indoor unit 10 as the indoor unit 10 having the largest pressure loss dP. The order of the length of the refrigerant pipe between the outdoor unit 30 and each indoor unit 10 may be determined by the operator when installing the refrigeration cycle device 1, and the order based on the determination may be stored in the outdoor unit memory 71. Similarly, the information on the order of the length of the refrigerant pipe may be replaced by information such as the thickness of the refrigerant pipe, the number of curved portions of the refrigerant pipe, the curvature, and the order of the height of the indoor unit 10, and a combination thereof. In addition, the device control unit 73a may control the indoor expansion valve 15 starting from the indoor unit 10 having the smallest measured value of the pressure of the working medium in the refrigerant pipe near each indoor unit 10 in operation as the indoor unit 10 having the largest pressure loss dP. The pressure of the working medium in the refrigerant pipe near each indoor unit 10 may be measured by, for example, a pressure sensor (not shown) connected to the indoor unit 10, and transmitted to the device control unit 73a via the indoor communication unit 14 and the outdoor communication unit 34. In this case, the device control unit 73a controls the indoor expansion valve 15 in consideration of not only the factors determined when the refrigeration cycle device 1 is installed, but also the pressure loss dP including factors such as the air conditioning load.

[0061] During the normal operation of the refrigeration cycle device 1 as described above, the working medium temperature sensor 32 continuously measures the discharge temperature T of the working medium discharged from the compressor 31 at a predetermined sampling rate, and sends the data of the measured value to the judgment unit 73b. The judgment unit 73b judges whether the received measured value of the discharge temperature T is above the predetermined temperature T1 (step S1). In the case where it is judged that the measured value of the discharge temperature T is less than the predetermined temperature T1 (step S1: No), the refrigeration cycle device 1 continues the normal operation. On the other hand, in the case where it is judged that the measured value of the discharge temperature T is above the predetermined temperature T1 (step S1: Yes), it moves to step S2.

[0062] In step S2, the device control unit 73a increases the opening of the indoor expansion valve 15 in the operating indoor unit 10 in order from the indoor unit with the smallest pressure loss dP from the compressor 31. As a result, the working medium moves rapidly from the high-pressure side to the low-pressure side in the refrigeration cycle. Therefore, the pressure on the high-pressure side in the refrigeration cycle drops sharply.

[0063] In step S3, the determination unit 73b determines whether all of the four indoor units 10 of the refrigeration cycle device 1 are operating. When the determination unit 73b determines that all of the indoor units 10 are operating (step S3: Yes), the process proceeds to step S4. When the determination unit 73b determines that not all of the indoor units 10 of the refrigeration cycle device 1 are operating (step S3: No), that is, when some of the indoor units 10 are operating and other indoor units 10 are not operating, the process proceeds to step S5.

[0064] In step S4, the determination unit 73b determines whether the indoor unit 10 in operation has stopped operating again. As a case where the indoor unit 10 stops operating again, for example, the indoor unit 10 in operation is stopped by the user, or the indoor unit 10 in operation is transferred to thermal cut-off operation. When the determination unit 73b determines that the indoor unit 10 in operation has stopped operating again (step S4: Yes), the process moves to step S5. The determination unit 73b repeats the determination of step S4 until the indoor unit 10 stops operating again.

[0065] In step S5 , the device control unit 73a opens the indoor expansion valve 15 of at least one of the stopped indoor units 10 . This allows the high-pressure side pressure in the refrigeration cycle to be easily released to the low-pressure side through the opened indoor expansion valve 15 .

[0066] The opening of the indoor expansion valve 15 opened in step S5 may also be an opening smaller than the minimum value of the opening of the indoor unit 10 in operation, that is, the minimum opening. This opening is hereinafter referred to as slightly open. The range of the opening used in the operation of the indoor unit 10 is determined, for example, by the relationship between the opening of the indoor expansion valve 15 and the Cv value specified in JIS B0100. Specifically, the range of the opening of the indoor expansion valve 15 used in the operation of the indoor unit 10 is an area where the Cv curve drawn with the opening of the indoor expansion valve 15 and the Cv value as axes is roughly a straight line, and in this embodiment, it is an area where the opening is about 5% or more. The minimum opening is the smallest opening in this area, so the minimum opening is about 5%. In the case of this embodiment, in the area where the opening is about 5% or less, the Cv value indicating the ease of flow of the fluid changes sharply relative to the change in the opening of the indoor expansion valve 15. Therefore, the area where the opening is about 5% or less is not suitable for controlling the flow rate of the working medium. Therefore, in the present embodiment, when the indoor unit 10 is operating, the device control unit 73a performs control so that the opening degree of the corresponding indoor expansion valve 15 does not become approximately 5% or less.

[0067] It is also possible to configure that, in step S5, the number and opening degree of the indoor expansion valves 15 opened among the indoor expansion valves 15 of the indoor unit 10 that is stopped are set according to the discharge temperature T. For example, it is also possible to configure that the total opening degree of the indoor expansion valves 15 opened in step S5 is controlled in a manner related to the temperature range at which the discharge temperature T exceeds the prescribed temperature T1. Thus, when the discharge temperature T is high temperature, the pressure on the high-pressure side of the refrigeration cycle is more likely to escape, so the occurrence of the disproportionation reaction can be effectively suppressed. However, from the viewpoint of energy efficiency, it is preferred to control in a manner such that the total opening degree of the indoor expansion valves 15 of the indoor unit 10 that is stopped becomes less than the total opening degree of the indoor expansion valves 15 of the indoor unit 10 that is in operation.

[0068] In addition, in step S5, the device control unit 73a may close the indoor expansion valve 15 of the indoor unit 10 having the human sensor 16 that is sensing a person among the indoor units 10 that are stopped, and set the opening of the indoor expansion valve 15 of the indoor unit 10 having the human sensor 16 that is not sensing a person to be slightly opened. Thus, in step S6 described later, it is possible to suppress the discomfort caused to the person near the indoor unit 10 by the rotation of the indoor fan 13 of the indoor unit 10 that is stopped.

[0069] In step S6, the indoor fan motor 13a of the indoor unit 10 having the indoor expansion valve 15 set to open in step S5 and in operation stop starts to drive under the control of the device control unit 73a. As a result, the indoor fan 13 rotates, and the working medium in the indoor heat exchanger 11 exchanges heat with the air. Therefore, the temperature of the working medium of the refrigeration cycle device 1 decreases. At this time, the device control unit 73a can also be configured so that the rotation speed of the indoor fan motor 13a of the indoor unit 10 where the human sensor 16 does not detect a person is lower than the rotation speed of the indoor fan motor 13a of the indoor unit 10 where the human sensor 16 detects a person. As a result, it is possible to suppress the discomfort caused to the person located near the indoor unit 10 due to the high-speed rotation of the indoor fan 13 of the indoor unit 10 in operation stop.

[0070] Thereafter, the refrigeration cycle device 1 repeats the operations of step S5 and step S6 until the discharge temperature T becomes lower than the second temperature T2 described later (step S7: No). During this period, when the indoor unit 10 in operation stops again, the device control unit 73a sets the opening of the indoor expansion valve 15 to a slightly open position for the indoor unit 10 that has stopped again, and drives the indoor fan motor 13a to rotate the indoor fan 13. In addition, when the indoor unit 10 in operation stops due to the transition to the thermal cut-off operation, there is a high possibility that a person is near the indoor unit 10. Therefore, the device control unit 73a may be configured to make the rotation speed of the indoor fan motor 13a of the indoor unit 10 that stops due to the transition to the thermal cut-off operation lower than the rotation speed of the indoor fan motor 13a of the indoor unit 10 that stops due to the transition to the thermal cut-off operation, for example.

[0071] In step S7, the determination unit 73b determines whether the discharge temperature T is higher than the second temperature T2. The second temperature T2 is a temperature lower than the predetermined temperature T1 by about 0K to 20K, and is 105°C in the present embodiment. When the determination unit 73b determines that the discharge temperature T is higher than the second temperature T2 (step S7: Yes), the process proceeds to step S5. On the other hand, when the determination unit 73b determines that the discharge temperature T is lower than the second temperature T2 (step S7: No), the process proceeds to step S8.

[0072] In step S8, when the indoor expansion valve 15 of the indoor unit 10 that is not in operation is open, the indoor expansion valve 15 is closed.

[0073] In step S9, when the indoor fan motor 13a of the indoor unit 10 in the stopped state is driven, the driving of the indoor fan motor 13a is stopped, and the rotation of the indoor fan 13 is stopped. Thus, the refrigeration cycle device 1 returns to the normal operation.

[0074] [1-3. Effects, etc.]

[0075] As described above, in the present embodiment, the refrigeration cycle device 1 is a refrigeration cycle device including an outdoor unit 30 and a plurality of indoor units 10, wherein the outdoor unit 30 includes a compressor 31, and the plurality of indoor units 10 include an indoor expansion valve 15, wherein a working medium containing ethylene fluoroolefin is used as a refrigerant, and the control unit 70 is included, and the control unit 70 opens the indoor expansion valve 15 of at least one of the indoor units 10 that is stopped when some of the indoor units 10 are operating and the discharge temperature T of the compressor 31 is above a prescribed temperature T1.

[0076] According to this configuration, the pressure in the refrigeration cycle is reduced by opening the indoor expansion valve 15 of the indoor unit 10 which is not in operation. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0077] When any one of the operating indoor units 10 stops operating, the control unit 70 opens the indoor expansion valve 15 of the stopped indoor unit 10 .

[0078] According to this configuration, the indoor expansion valve 15 of the stopped indoor unit 10 is opened without closing, thereby suppressing a sudden pressure rise in the refrigeration cycle circuit accompanying a decrease in the number of operating indoor units 10. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0079] The control unit 70 rotates the indoor fan 13 of the indoor unit 10 having the indoor expansion valve 15 opened among the indoor units 10 that are stopped.

[0080] According to this configuration, the temperature of the working medium in the refrigeration cycle can be lowered, thereby suppressing the occurrence of the disproportionation reaction without impairing the convenience of the user of the air conditioner.

[0081] The control unit 70 slightly opens the opening degree of the indoor expansion valve 15 of at least one of the indoor units 10 that are not in operation.

[0082] According to this structure, the flow rate of the working medium passing through the stopped indoor unit 10 can be suppressed, and the pressure in the refrigeration cycle circuit can be reduced. Therefore, the energy loss caused by the working medium flowing through the stopped indoor unit 10 can be suppressed, and the occurrence of the disproportionation reaction can be suppressed.

[0083] The slightly opened position is an opening smaller than the minimum opening of the indoor expansion valve 15 of the indoor unit 10 in operation.

[0084] According to this structure, the flow rate of the working medium passing through the stopped indoor unit 10 can be suppressed, and the pressure in the refrigeration cycle circuit can be reduced. Therefore, the energy loss caused by the working medium flowing through the stopped indoor unit 10 can be suppressed, and the occurrence of the disproportionation reaction can be suppressed.

[0085] The control unit 70 increases the opening degree of the indoor expansion valve 15 per unit condensing capacity or evaporating capacity of the indoor unit 10 in order from the indoor unit 10 having a large pressure loss dP from the compressor 31 among the operating indoor units 10 .

[0086] According to this structure, even if the total condensing capacity or evaporation capacity required by all indoor units 10 changes and the discharge amount of the compressor 31 changes, it is possible to suppress an excessive increase in the pressure in the refrigeration cycle. In addition, when the indoor unit 10 is in cooling operation, it is possible to suppress an increase in the cooling and heating degree of the working medium flowing out of the indoor unit 10, and it is possible to suppress an increase in the discharge temperature T of the compressor 31. Therefore, the occurrence of the disproportionation reaction can be suppressed.

[0087] When some of the plurality of indoor units 10 are operating and the discharge temperature T is equal to or higher than a predetermined temperature T1, the control unit 70 increases the opening of the indoor expansion valve 15 in order from the operating indoor unit 10 having the smallest pressure loss dP from the compressor 31 .

[0088] According to this structure, the refrigerant on the high-pressure side in the refrigeration cycle can be quickly moved to the low-pressure side. As a result, when the refrigeration cycle device 1 is operated under a condition of a large air conditioning load, when the number of indoor units 10 in operation is reduced, etc., an excessive pressure increase in the refrigeration cycle can be suppressed. Therefore, the occurrence of the disproportionation reaction can be suppressed.

[0089] (Other Embodiments)

[0090] As described above, as an example of the technology disclosed in this application, embodiment 1 is described. However, the technology in the present disclosure is not limited thereto, and can also be applied to embodiments that have been changed, replaced, added, omitted, etc. In addition, the various components described in the above embodiment 1 can also be combined as a new embodiment.

[0091] Therefore, other embodiments are exemplified below.

[0092] In the first embodiment, the control unit 70 opens the indoor expansion valve 15 of the indoor unit 10 that is not in operation when the discharge temperature T is determined to be higher than the predetermined temperature T1 (step S1: Yes) and when some of the indoor units 10 are in operation (step S3: No), but this is an example. For example, it is also possible to configure that, regardless of the discharge temperature T, when there is an indoor unit 10 that is not in operation, the indoor expansion valve 15 provided in at least one indoor unit 10 that is not in operation is always opened, and its opening degree is slightly opened.

[0093] That is, the refrigeration cycle device 1 can also be configured as follows: in a refrigeration cycle device having an outdoor unit 30 including a compressor 31 and a plurality of indoor units 10 including an indoor expansion valve 15, a working medium containing ethylene fluoroolefin is used as a refrigerant, and when some of the plurality of indoor units 10 are operating, at least one of the indoor units 10 that is stopped always sets the opening of the indoor expansion valve 15 to a slightly open state.

[0094] According to this configuration, the pressure in the refrigeration cycle is reduced by opening the indoor expansion valve 15 of the indoor unit 10 which is not in operation. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0095] In the first embodiment, the working medium temperature sensor 32 is used to measure the discharge temperature T of the working medium discharged from the compressor 31, but this is an example. For example, a pressure sensor (not shown) may be installed on the discharge side of the compressor 31, and an estimated value of the discharge temperature T may be calculated from the pressure value measured by the pressure sensor using the correlation between the temperature and pressure of the working medium.

[0096] In Embodiment 1, it is described that when the discharge temperature T is lower than the second temperature T2 (step S7: No), the control unit 70 closes the indoor expansion valve 15 of the indoor unit 10 that is not in operation, but this is an example. For example, the control unit 70 may be configured such that when the indoor expansion valve 15 of the indoor unit 10 that is not in operation is already opened (step S5), the indoor expansion valve 15 is closed after a predetermined time has passed since it was opened. Thus, a sharp pressure rise in the refrigeration cycle circuit is suppressed, and the working medium does not continue to flow to the indoor unit 10 that is not in operation for a long time. Therefore, the occurrence of the disproportionation reaction can be suppressed, and the energy efficiency of the refrigeration cycle device 1 can be improved.

[0097] In the first embodiment, the human sensor 16 is described as an infrared sensor, but this is an example. For example, the human sensor 16 may be a camera, and the refrigeration cycle device 1 may determine whether a person is near the indoor unit 10 based on the image data. In addition, the human sensor 16 may be an ultrasonic sensor, and the refrigeration cycle device 1 may determine whether a person is near the indoor unit 10 based on the reflection intensity of the generated ultrasonic wave.

[0098] The outdoor unit processor 73 may be composed of a plurality of processors or a single processor. The outdoor unit processor 73 may also be hardware that implements corresponding functional units through programming. That is, the outdoor unit processor 73 may be composed of, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0099] Figure 3 The parts shown are just an example, and the specific installation form is not particularly limited. That is, it is not necessary to install hardware corresponding to each part separately, and of course, it can also be configured so that the functions of each part are realized by executing a program by a processor. In addition, in the above-mentioned embodiment, part of the function realized by software can be configured as hardware, or part of the function realized by hardware can be realized by software. In addition, the specific detailed structure of each part of the indoor unit 10 and the outdoor unit 30 can also be arbitrarily changed within the scope of the main purpose of the present invention.

[0100] Figure 4 The step units of the actions shown are units divided according to the main processing contents in order to facilitate understanding of the actions of the various parts of the refrigeration cycle device 1, and the actions are not limited by the division method or name of the processing units. Depending on the processing contents, it can also be divided into more step units. In addition, it can also be divided into a step unit containing more processing. In addition, the order of the steps can also be appropriately replaced within the scope that does not hinder the main purpose of the present invention.

[0101] [Structure supported by the above-mentioned embodiment]

[0102] The above-mentioned embodiment supports the following structure.

[0103] (Note)

[0104] (Technology 1) A refrigeration cycle device, comprising: an outdoor unit having a compressor; and a plurality of indoor units having expansion valves, wherein the refrigeration cycle device is characterized in that a working medium containing ethylene fluoroolefin is used as a refrigerant, and the refrigeration cycle device includes a control unit, which opens the expansion valve of at least one of the indoor units that is stopped when some of the plurality of indoor units are operating and the discharge temperature of the compressor is above a specified temperature.

[0105] As a result, the expansion valve of the indoor unit in the stopped state is opened, and the pressure in the refrigeration cycle circuit is reduced. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0106] (Technique 2) The refrigeration cycle device according to Technique 1 is characterized in that when any one of the indoor units in operation stops operating, the control unit opens the expansion valve of the stopped indoor unit.

[0107] Thus, the expansion valve of the stopped indoor unit is opened without closing it, and the rapid pressure rise in the refrigeration cycle circuit accompanying the reduction in the number of operating indoor units can be suppressed. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0108] (Technique 3) The refrigeration cycle device according to Technique 1 or 2 is characterized in that the control unit rotates the indoor fan of the indoor unit having the open expansion valve in the indoor unit that is in a stopped state.

[0109] This makes it possible to lower the temperature of the working medium in the refrigeration cycle circuit. This makes it possible to suppress the occurrence of the disproportionation reaction without impairing the convenience of the user of the air conditioner.

[0110] (Technique 4) The refrigeration cycle device according to any one of Techniques 1 to 3 is characterized in that the control unit sets the opening degree of the expansion valve of at least one of the indoor units that are stopped to a slightly open position.

[0111] This can suppress the flow rate of the working medium passing through the stopped indoor unit and reduce the pressure in the refrigeration cycle. Therefore, it is possible to suppress energy loss caused by the working medium flowing through the stopped indoor unit and suppress the occurrence of disproportionation reaction.

[0112] (Technique 5) The refrigeration cycle device according to Technique 4 is characterized in that the above-mentioned slight opening is an opening smaller than the minimum opening of the above-mentioned expansion valve of the above-mentioned indoor unit in operation.

[0113] This can suppress the flow rate of the working medium passing through the stopped indoor unit and reduce the pressure in the refrigeration cycle. Therefore, it is possible to suppress energy loss caused by the working medium flowing through the stopped indoor unit and suppress the occurrence of disproportionation reaction.

[0114] (Technology 6) A refrigeration cycle device according to any one of Technologies 1 to 5, characterized in that the control unit increases the opening degree of the expansion valve per unit condensing capacity or evaporating capacity of the indoor units in operation, starting from the indoor units having a large pressure loss from the compressor.

[0115] Thus, even when the total condensing capacity or evaporation capacity required by all indoor units changes and the discharge volume of the compressor changes, it is possible to suppress an excessive increase in the pressure in the refrigeration cycle. In addition, when the indoor unit is in cooling operation, it is possible to suppress an increase in the degree of cooling and heating of the working medium flowing out of the indoor unit, and suppress an increase in the discharge temperature of the compressor. Therefore, it is possible to suppress the occurrence of a disproportionation reaction.

[0116] (Technology 7) A refrigeration cycle device according to any one of Technologies 1 to 6, characterized in that when a part of the plurality of indoor units are in operation and the discharge temperature is above the specified temperature, the control unit increases the opening of the expansion valve in sequence, starting from an indoor unit in operation having a smaller pressure loss from the compressor.

[0117] As a result, the refrigerant on the high-pressure side of the refrigeration cycle can be quickly moved to the low-pressure side. As a result, when the refrigeration cycle device is operated under a condition of a large air-conditioning load, when the number of indoor units in operation is reduced, etc., an excessive pressure rise in the refrigeration cycle can be suppressed. Therefore, the occurrence of the disproportionation reaction can be suppressed.

[0118] (Technology 8) A refrigeration cycle device, comprising: an outdoor unit having a compressor; and a plurality of indoor units having expansion valves, wherein the refrigeration cycle device is characterized in that a working medium containing ethylene-based fluoroolefin is used as a refrigerant, and when some of the plurality of indoor units are in operation, at least one of the indoor units that is in a stopped state always sets the opening of the expansion valve to a slightly open state.

[0119] As a result, the expansion valve of the indoor unit in the stopped state is opened, and the pressure in the refrigeration cycle circuit is reduced. Therefore, the occurrence of the disproportionation reaction can be suppressed without impairing the comfort of the user of the air conditioner.

[0120] Industrial Application Possibility

[0121] The present invention can be applied to a refrigeration cycle device using a working medium containing ethylene fluoroolefin. Specifically, the present invention can be applied to an air conditioning device using a working medium containing ethylene fluoroolefin.

[0122] Explanation of symbols

[0123] 1 Refrigeration cycle device

[0124] 10 Indoor unit

[0125] 11 Indoor heat exchanger

[0126] 12 Room temperature sensor

[0127] 13 Indoor fan

[0128] 13a Indoor fan motor

[0129] 14 Indoor Communications Department

[0130] 15Indoor expansion valve (expansion valve)

[0131] 16 Human sensor

[0132] 20 Gas pipe

[0133] 30 Outdoor unit

[0134] 31 Compressor

[0135] 32 Working medium temperature sensor

[0136] 33 Four-way valve

[0137] 34 Outdoor Communications Department

[0138] 35 Outdoor heat exchanger

[0139] 37 Outdoor fan

[0140] 37a Outdoor fan motor

[0141] 39 Outdoor expansion valve

[0142] 40 Liquid pipe

[0143] 70 Control Department

[0144] 71 Outdoor unit memory

[0145] 73 Outdoor unit processor

[0146] 73a Equipment control unit

[0147] 73b Judgment Department

[0148] 75 Outdoor unit interface

[0149] B Buildings.

Claims

1. A refrigeration cycle device, comprising: An outdoor unit having a compressor; and a plurality of indoor units having expansion valves, wherein the refrigeration cycle device is characterized in that: Using a working medium containing ethylene fluoroolefins as a refrigerant, The refrigeration cycle device includes a control unit, The control unit opens the expansion valve of at least one of the indoor units that is stopped, when some of the plurality of indoor units are operating and the discharge temperature of the compressor is equal to or higher than a predetermined temperature.

2. The refrigeration cycle device according to claim 1, characterized in that: When any one of the indoor units in operation stops operating, the control unit opens the expansion valve of the indoor unit that has stopped operating.

3. The refrigeration cycle device according to claim 1, characterized in that: The control unit rotates the indoor fan of the indoor unit having the opened expansion valve among the indoor units that are stopped.

4. The refrigeration cycle device according to claim 1, characterized in that: The control unit slightly opens the expansion valve of at least one of the indoor units that are in a stopped state.

5. The refrigeration cycle device according to claim 4, characterized in that: The slightly opened position is an opening smaller than the minimum opening of the expansion valve of the indoor unit in operation.

6. The refrigeration cycle device according to claim 1, characterized in that: The control unit increases the opening degree of the expansion valve per unit condensing capacity or evaporating capacity of the indoor unit in order from an indoor unit having a large pressure loss from the compressor among the operating indoor units.

7. The refrigeration cycle device according to claim 1, characterized in that: When some of the plurality of indoor units are operating and the discharge temperature is equal to or higher than the predetermined temperature, the control unit increases the opening of the expansion valve in order from an indoor unit having a smaller pressure loss from the compressor among the operating indoor units.

8. A refrigeration cycle device, comprising: An outdoor unit having a compressor; and a plurality of indoor units having expansion valves, wherein the refrigeration cycle device is characterized in that: Using a working medium containing ethylene fluoroolefins as a refrigerant, When some of the plurality of indoor units are in operation, at least one of the indoor units in a stopped state always keeps the opening degree of the expansion valve slightly opened.

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