CONTROL DEVICE OF A COOLING CIRCUIT DEVICE, OUTDOOR UNIT AND COOLING CIRCUIT DEVICE

Abstract

Once an evaporation temperature reaches a target value, and in a case where the outside air temperature falls below ultra-low ambient conditions (lower than standard ambient conditions) and is below a low-temperature controlled ambient threshold, an operating control circuit of a refrigeration circuit device is configured to substitute a compressor off value with a value lower than a preset outside air temperature lower limit. The low-temperature controlled ambient threshold is a value lower than both the evaporation temperature target and the ultra-low ambient condition threshold, which defines the ultra-low ambient conditions.After substituting the compressor off-value, the operating control circuit is configured to continue compressor operation if the evaporation temperature is higher than the substituted compressor off-value. Conversely, after substituting the compressor off-value, the operating control circuit is configured to stop compressor operation if the evaporation temperature is lower than or equal to the substituted compressor off-value.After the compressor has stopped operating, the operating control circuit is set up to resume compressor operation either in a case where both a first condition, in which the evaporation temperature is higher than the compressor off-value so substituted, and a second condition, in which a preset time period expires after the compressor has stopped operating, are met, or in a case where the evaporation temperature is higher than or equal to a first threshold, which represents a temperature higher than the compressor off-value so substituted and lower than the ultra-low outside air condition threshold.

Description

Technical area

[0001] The present disclosure relates to a control device of a refrigeration cycle device, an outdoor unit, and a refrigeration cycle device used in a low outside air temperature environment. Technological background

[0002] There has been a refrigeration cycle device including an indoor unit including an evaporator and an outdoor unit including a compressor, a radiator, and an expansion valve. In a case where this type of refrigeration cycle device operates at low outside air temperatures, a low load causes excess cooling capacity even while the compressor is operating at the minimum possible frequency, resulting in an increase in the frequency at which the compressor starts and stops. To solve this problem, there is a refrigeration cycle device configured for a low cooling capacity by reducing the amount of refrigerant flowing through the evaporator, reducing the frequency at which the compressor starts and stops, and maintaining the interior of a bearing at an appropriate temperature (see, for example, Patent Literature 1). Citation listPatent literature

[0003] Patent Literature 1: Unexamined Japanese Patent Application with Publication No. 2019-66068 Summary of the inventionTechnical problem

[0004] However, Patent Literature 1 does not consider a case of an outside air temperature falling under ultra-low outside air conditions lower in temperature than a low outside air, and it is not clear whether Patent Literature 1 can maintain a desired temperature inside the warehouse under the ultra-low outside air conditions.

[0005] The present disclosure has been made in view of such a problem and has an object to provide a control device of a refrigeration cycle device, an outdoor unit, and a refrigeration cycle device that make it possible to maintain a temperature to be achieved inside a warehouse under ultra-low outside air conditions that are lower than low outside air in terms of outside air temperature. Solution to the problem

[0006] A control device of a refrigeration cycle device according to an embodiment of the present disclosure is a control device of a refrigeration cycle device including a refrigerant circuit including a compressor and an evaporator. The control device includes an operation control circuit configured to perform normal control of stopping the compressor in a case where an evaporation temperature of the evaporator is lower than or equal to a compressor off-value for use in normal control, which is an evaporation temperature set according to a target evaporation temperature, and resuming operation of the compressor in a case where the evaporation temperature of the evaporator is higher than the compressor off-value and a set period of time, which is set in advance, elapses after stopping the operation of the compressor.The operation control circuit is configured to perform normal control in a case where an outside air temperature falls below low outside air conditions that are set in advance. After the evaporating temperature reaches the evaporating temperature target value and either in a case where the outside air temperature falls below the ultra-low outside air conditions that are lower than the low outside air conditions and the outside air temperature is lower than a low-temperature controlled ambient threshold, or in a case where the outside air temperature falls below the ultra-low outside air conditions and either one or both of the evaporating temperature target value and the compressor off value are lower than the thresholds.which are set separately in accordance with each of the values, the operation control circuit is configured to substitute the compressor off-value with a value that is smaller than a preset outside air temperature lower limit. The low-temperature controlled ambient threshold is a value that is smaller than the evaporation temperature target value and that is smaller than an ultra-low outside air condition threshold, which is a threshold for determining the ultra-low outside air conditions. After substituting the compressor off-value, the operation control circuit is configured to continue the operation of the compressor in a case where the evaporation temperature is higher than the thus-substituted compressor off-value.After substituting the compressor off-value, the operation control circuit is configured to stop the operation of the compressor in a case where the evaporation temperature is less than or equal to the thus substituted compressor off-value.After stopping the operation of the compressor, the operation control circuit is configured to resume the operation of the compressor in a case where both a first condition in which the evaporating temperature is higher than the thus substituted compressor off value and a second condition in which the set time period, which is set in advance, elapses after stopping the operation of the compressor are met, or to resume the operation of the compressor in a case where the evaporating temperature is greater than or equal to a first threshold representing a temperature higher than the thus substituted compressor off value and lower than the ultra-low outside air condition threshold.

[0007] An outdoor unit according to an embodiment of the present disclosure includes the control device of the refrigeration cycle device and a compressor.

[0008] A refrigeration cycle device according to an embodiment of the present disclosure includes the refrigeration cycle device control device, a compressor, a radiator, an expansion valve, and an evaporator. Advantageous effects of the invention

[0009] According to an embodiment of the present disclosure, the operation control circuit performs the normal control in a case where an outside air temperature falls below low outside air conditions that are set in advance and after the evaporation temperature reaches the evaporation temperature target value, and in a case where the outside air temperature falls below ultra-low outside air conditions that are lower than the low outside air conditions, and the outside air temperature is lower than a low-temperature controlled ambient threshold, wherein the operation control circuit is configured to substitute the compressor off value with a value that is lower than an outside air temperature lower limit.Furthermore, the operation control circuit is configured, after substituting the compressor off-value, to stop the operation of the compressor in a case where the evaporation temperature is less than or equal to the thus substituted compressor off-value.After stopping the operation of the compressor, the operation control circuit is configured to resume the operation of the compressor either in a case where both a first condition in which the evaporating temperature is higher than the thus substituted compressor off value and a second condition in which the set time period, which is set in advance, elapses after stopping the operation of the compressor are met, or in a case where the evaporating temperature is higher than or equal to a first threshold representing a temperature higher than the thus substituted compressor off value and lower than the ultra-low outside air condition threshold.This makes it possible to prevent the compressor from failing to resume operation after the compressor's operation is stopped in a low-temperature controlled environment where the refrigeration cycle device is used under ultra-low outside air conditions, and in particular, the outside air temperature is lower than the low-temperature controlled environment threshold. Therefore, the operation control circuit is configured to prevent the temperature inside a warehouse from increasing, making it possible to maintain a desired temperature inside the warehouse. Short description of the drawings [ Fig. 1] Fig. 1 illustrates a refrigerant circuit diagram of a refrigeration cycle device according to Embodiments 1 and 2. [ Fig. 2] Fig. Figure 2 is a functional block diagram showing an example of a control device used in Fig. 1 is shown. [ Fig. 3] Fig. 3 shows a hardware configuration diagram showing an example configuration of the Fig. 2 shows the control device. [ Fig. 4] Fig. 4 shows a hardware configuration diagram showing another example configuration of the Fig. 2 shows the control device. [ Fig. 5] Fig. 5 illustrates a control flowchart in a refrigeration cycle device of a comparative example. [ Fig. 6] Fig. Fig. 6 is an explanatory diagram of an example of a compressor off value in a control of the Fig. 5. [ Fig. 7] Fig. 7 illustrates a control flowchart in the refrigeration cycle device according to Embodiment 1. [ Fig. 8] Fig. Fig. 8 is an explanatory diagram showing examples of a compressor off value for use in a normal control and a compressor off value for use in an ultra-low outside air environment in a control of the Fig. 7. [ Fig. 9] Fig. 9 is an explanatory diagram of a thermo-on and a thermo-off of a compressor under low outside air conditions in the refrigeration cycle device according to Embodiment 1. [ Fig. 10] Fig. 10 is an explanatory diagram of a thermo-turn-on and a thermo-turn-off of the compressor under ultra-low outside air conditions in the refrigeration cycle device according to Embodiment 1. [ Fig. 11] Fig. 11 is a diagram showing another exemplary configuration of the refrigeration cycle device according to Embodiment 1. [ Fig. 12] Fig. 12 illustrates a control flowchart in the refrigeration cycle device according to Embodiment 2. Description of the embodiments

[0010] The following describes embodiments of the present disclosure in detail with reference to the drawings. Embodiment 1.

[0011] Fig. 1 illustrates a refrigerant circuit diagram of a refrigeration cycle device according to Embodiments 1 and 2. The refrigeration cycle device includes an outdoor unit 10 and an indoor unit 11. The outdoor unit 10 and the indoor unit 11 are independent units.

[0012] The outdoor unit 10 includes at least a compressor 1, a radiator 2, an outside air temperature sensor 5, an intake pressure sensor 6, and an outlet pressure sensor 7. The indoor unit 11 includes at least an expansion valve 3 and an evaporator 4. Furthermore, the compressor 1, the radiator 2, the expansion valve 3, and the evaporator 4 are connected via pipes, thus forming a refrigerant circuit A. The refrigeration cycle device including the refrigerant circuit A is configured, for example, to cool a warehouse and cool goods within the warehouse that are sold in stores by performing a refrigeration cycle operation.

[0013] The compressor 1 compresses a refrigerant drawn in from the evaporator 4 and discharges the refrigerant toward the radiator 2. The operating frequency of the compressor 1 can be arbitrarily changed by an inverter controller. The compressor 1 is configured such that its rotational speed is adjusted in accordance with a control signal from a controller 8, which will be described later. Adjusting the rotational speed of the compressor 1 causes the amount of circulating refrigerant to be adjusted, making it possible to adjust the capacity of the refrigeration cycle device. Various types of compressor 1 can be employed. For example, the compressor 1 employed could be a scroll compressor, a rotary compressor, a screw compressor, or other types.

[0014] The radiator 2 is a condenser or a gas cooling device. The radiator 2 is configured so that high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 releases heat by heat exchange with outside air. For example, in a case where the refrigerant is a refrigerant used at or below a critical point, such as a fluorocarbon refrigerant, the radiator 2 is used as a condenser when the refrigerant condenses during a heat-releasing operation. Alternatively, in a case where the refrigerant is a refrigerant used at or below a critical point, such as a CO2 refrigerant, the radiator 2 is used as a gas cooling device. A heat exchanger used during a heat-releasing operation is referred to herein as a "radiator," regardless of the type of refrigerant.

[0015] In a case where the radiator 2 is used as a condenser, the refrigerant releases heat through heat exchange with a heat medium passing through the radiator 2 and is condensed into a liquid phase. In a case where the radiator 2 is used as a gas cooler, the refrigerant releases heat through heat exchange with the heat medium. During this heat exchange, the refrigerant releases heat without undergoing a phase change when the refrigerant is in a supercritical state. After releasing heat, the refrigerant flows out toward the expansion valve 3. The heat medium that exchanges heat with the refrigerant could be a gas, such as outside air around the outdoor unit 10, or could be, for example, a liquid, such as water and a brine, and the heat medium could be of any type and in any state.In a case where the heat medium is outside air around the outdoor unit 10, the radiator 2 of the refrigeration cycle device could be provided with a fan configured to send outside air for increased heat exchange efficiency.

[0016] The expansion valve 3 is, for example, an electronic expansion valve configured to decompress the refrigerant. It should be noted that the expansion valve 3 could, for example, be a temperature expansion valve controlled independently of the outdoor unit 10. The evaporator 4 performs heat exchange between air and the refrigerant. In the refrigeration cycle device, the evaporator 4 evaporates the refrigerant by extracting heat from the air in a cooling target space. The heat medium that exchanges heat with the refrigerant could, for example, be the air in the cooling target space or could, for example, be a liquid such as water and brine, and the heat medium could be of any type and in any state.

[0017] The refrigerant circuit forms a circulation flow passage through which the refrigerant flows through the compressor 1, the radiator 2, the expansion valve 3 and the evaporator 4. Arrows in Fig. 1 indicate the flow of the coolant. This circulation flow passage is also referred to as the "main circuit" below. For example, a coolant circuit component, such as a receiver and an expansion valve, a temperature sensor configured to detect the temperature of each component of the main circuit, and a pressure sensor configured to detect the pressure of each component of the main circuit, could be added to this main circuit as needed. Furthermore, the refrigeration cycle device could include an injection circuit, a bypass circuit, or other circuits branching off from the main circuit as needed. The injection circuit is a circuit that, for example, cools a gaseous coolant discharged from the compressor 1. The bypass circuit is a circuit designed to bypass high and low pressures.For example, a refrigerant circuit component such as a receiver and the expansion valve 3, a temperature sensor configured to detect the temperature of each component of the main circuit, and a pressure sensor configured to detect the pressure of each component of the main circuit could be added to these branch circuits as needed.

[0018] The outside air temperature sensor 5 detects an outside air temperature and outputs a detected value of the outside air temperature to the controller 8. The intake pressure sensor 6 detects an intake pressure representing a pressure of a gaseous refrigerant that the compressor 1 sucks in and outputs a detected value of the intake pressure to the controller 8. The discharge pressure sensor 7 detects an outlet pressure representing the pressure of a gaseous refrigerant that the compressor 1 discharges and outputs a detected value of the outlet pressure to the controller 8.

[0019] The refrigeration cycle device further comprises the control device 8, which is configured to control the refrigeration cycle device as a whole. The control device 8 controls the compressor 1 based on the detected values ​​output separately by each of the sensors.

[0020] Fig. Figure 2 is a functional block diagram showing an example of the control device used in Fig. 1. The controller 8 includes an operation control circuit 81, a conversion circuit 82, a storage circuit 83, a determination circuit 84, and a calculation circuit 85. The operation control circuit 81 performs a cooling operation based on the detected values ​​output from the outside air temperature sensor 5 and the intake pressure sensor 6. In normal control, the operation control circuit 81 performs an operation of controlling the operation frequency of the compressor 1 such that an evaporation temperature reaches a target evaporation temperature. The operation frequency of the compressor 1 is set based on, for example, a cooling load.More specifically, this means that the larger the temperature difference between the evaporation temperature and the evaporation temperature target value, the higher the operating frequency of the compressor 1 is set, and the smaller the temperature difference between the evaporation temperature and the evaporation temperature target value, the lower the operating frequency of the compressor 1 is set.

[0021] The evaporation temperature target value can be freely changed as needed by a user of the refrigeration cycle device. The evaporation temperature target value is set as a value lower than the target temperature of the interior of the warehouse. While a case is described here in which the user sets the evaporation temperature target value, the user could set the target temperature of the interior of the warehouse, and the refrigeration cycle device could automatically set a temperature obtained by subtracting a preset value from the target temperature of the interior of the warehouse set by the user at the evaporation temperature target value.

[0022] Furthermore, in a case where outside air conditions fall under conditions other than low outside air conditions and ultra-low outside air conditions, which will be described later, the operation control circuit 81 performs thermo-turn-on and thermo-turn-off based on a compressor on value and a compressor off value, which will be described later, for use in normal control, which are stored in the storage circuit 83. Thermo-turn-off means stopping the operation of the compressor 1 once the evaporating temperature reaches the compressor off value. Thermo-turn-on means resuming the operation of the compressor 1 once the evaporating temperature reaches the compressor on value.

[0023] The converter circuit 82 converts the pressure detected by the intake pressure sensor 6 into the evaporation temperature. The conversion is performed using a saturation temperature. In the case of the aforementioned configuration, where the injection circuit, the bypass circuit, or other circuits branch off from the main circuit, the converter circuit 82 could convert a pressure detected by a pressure sensor added to these branch circuits as needed into the evaporation temperature.

[0024] The storage circuit 83 stores a compressor on-value and a compressor off-value, which are determined in advance for each evaporation temperature target value, the maximum possible frequency of the compressor during use, the minimum possible frequency of the compressor during use, a threshold for determining the low outside air conditions, and a threshold for determining the ultra-low outside air conditions. The maximum possible frequency during use here means a maximum possible frequency required for the compressor 1 to operate safely without failure. Furthermore, the minimum possible frequency of the compressor during use here means a minimum possible frequency required for the compressor 1 to operate safely without failure. In the storage circuit 83, all contents related to the control of the refrigeration cycle device of the Fig. 1, as well as the various data types mentioned above.

[0025] The compressor off value stored in the storage circuit 83 is a compressor off value for use in normal control and, as mentioned above, is a value set according to an evaporation temperature target value. The compressor off value for use in normal control is set to a temperature moderately lower than the evaporation temperature target value. A compressor on value for use in normal control is set to a value higher than the compressor off value and lower than the evaporation temperature target value, and specifically, for example, is set to a value between these two values.More specifically, this means that in a case where the evaporation temperature target value is, for example, -5 °C, the compressor off value for use in normal control is set to, for example, -15 °C, and the compressor on value for use in normal control is set to, for example, -10 °C. The refrigeration cycle device is configured to prevent the temperature inside the warehouse from becoming higher than the evaporation temperature target value by setting both the compressor on value and the compressor off value for use in normal control to temperatures lower than the evaporation temperature target value.

[0026] For example, the threshold for determining low outdoor air conditions (hereinafter referred to as the "low outdoor air condition threshold") is 0°C. If the outdoor air temperature is lower than 0°C, it is determined that the outdoor air temperature meets the low outdoor air conditions. Note that 0°C is merely an example, and any numerical value is available. A case in which the outdoor air temperature meets the low outdoor air conditions may be referred to as a "low outdoor air environment" hereinafter.

[0027] For example, the threshold for determining ultra-low outdoor air conditions (hereinafter referred to as the "ultra-low outdoor air condition threshold") is -15°C. If the outdoor air temperature is lower than -15°C, the outdoor air temperature is determined to meet the ultra-low outdoor air conditions. The threshold for determining ultra-low outdoor air conditions only needs to be lower than the threshold for determining low outdoor air conditions, and any numerical value is available. A case in which the outdoor air temperature meets the ultra-low outdoor air conditions could hereinafter be referred to as an "ultra-low outdoor air environment."

[0028] The determination circuit 84 determines whether the evaporation temperature has reached the compressor on-value or the compressor off-value, whether the compressor 1 has stopped, whether the outside air temperature detected by the outside air temperature sensor 5 falls below the low outside air conditions or the ultra-low outside air conditions, and whether the outside air temperature is lower than the compressor on-value. Furthermore, the determination circuit 84 determines whether it is necessary to reduce the speed of the compressor, whether the compressor is starting or stopping, whether it is necessary to change the compressor on-value, and whether it is necessary to change the compressor off-value. Furthermore, the determination circuit 84 is configured, in addition to the aforementioned determinations, to make all determinations related to the control of the refrigeration cycle device of the Fig. 1 concern.

[0029] The calculation circuit 85 calculates a compressor stop time. The compressor stop time is, for example, an integrated time period from a compressor stop due to a thermal shutdown to the current time. As soon as the determination circuit 84 determines that compressor 1 is stopped, the calculation circuit 85 begins to calculate the compressor stop time. In addition to calculating the compressor stop time, the calculation circuit 85 is configured to perform all calculations related to the control of the refrigeration cycle device of the Fig. 1, such as calculating a compressor operating time and calculating an average of pressures detected by the intake pressure sensor 6.

[0030] An example of hardware used in Fig. The control device shown in Figure 2 is described here. Fig. 3 shows a hardware configuration diagram showing an example configuration of the Fig. 2. In a case where the various functions of the control device 8 are implemented by hardware, the Fig. 2 shown control device 8 a processing circuit 80, as in Fig. 3. The functions of the operation control circuit 81, the converter circuit 82, the memory circuit 83, the determination circuit 84 and the calculation circuit 85 shown in Fig. 2 are implemented by the processing circuit 80.

[0031] In a case where the various functions are implemented by hardware, the processing circuit 80 corresponds, for example, to a single circuit, a complex circuit, a programmed processor, a parallel-programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of the foregoing. The functions of means such as the operation control circuit 81, the converter circuit 82, the storage circuit 83, the determination circuit 84, and the calculation circuit 85 could be implemented by respective processing circuits 80 or could be implemented by one processing circuit 80.

[0032] Furthermore, another example of hardware of the control device 8 is described, which is shown in Fig. 2 is shown. Fig. 4 is a hardware configuration diagram showing another exemplary configuration of the Fig. 2. In a case where the various functions of the control device 8 are implemented by software, the control device 8 comprises a processor 80a and a memory 80b, as shown in Fig. 3. The functions of the operation control circuit 81, the conversion circuit 82, the storage circuit 83, the determination circuit 84, and the calculation circuit 85 are implemented by the processor 80a and the memory 80b.

[0033] In a case where the various functions are implemented by software, the functions of the operation control circuit 81, the conversion circuit 82, the storage circuit 83, the determination circuit 84, and the calculation circuit 85 are implemented by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in the memory 80b. The processor 80a implements the functions of parts of the circuit by reading and executing the programs stored in the memory 80b.

[0034] Useful examples of memory 80b include non-volatile semiconductor memory, such as read-only memory (ROM), flash memory, erasable programmable ROM (EPROM), and electrically erasable programmable ROM (EEPROM). Further, useful examples of memory 80b could include volatile semiconductor memory, such as random access memory (RAM). Furthermore, useful examples of memory 80b could include a removable storage medium, such as a magnetic disk, a floppy disk, an optical disk, a compact disc (CD), a minidisc (MD), and a digital versatile disc (DVD).

[0035] Next, a control of a comparative example will be described before a description of a control of Embodiment 1.

[0036] Fig. 5 shows a control flowchart in a refrigeration cycle device of the comparative example. A control of the Fig. 5 is performed in a case where an outside air temperature falls below 0 °C during operation under the low outside air conditions. Fig. Fig. 6 is an explanatory diagram of an example of a compressor off value in controlling the Fig. 5. In the Fig. 6, the label "OTHER CONDITIONS" indicates conditions other than ultra-low outside air conditions and low outside air conditions. This describes a case where an evaporator temperature target value is -5°C and a compressor off value for use in normal control is -15°C. In the following, the compressor off value represents a value for use in normal control, unless otherwise stated.

[0037] First, the refrigeration cycle device performs normal control (step ST1). In normal control, the refrigeration cycle device performs an operation of controlling the operating frequency of the compressor so that the evaporation temperature reaches a target evaporation temperature. Furthermore, in normal control performed in a case where the outside air temperature drops below the low outside air conditions, the refrigeration cycle device does not use a compressor on-value, but performs thermo-on and thermo-off based on the compressor off-value.

[0038] The refrigeration cycle device determines whether the evaporation temperature, which is a saturation temperature into which the intake pressure detected by the intake pressure sensor 6 has been converted, has reached the evaporation temperature target value (step ST2). If the evaporation temperature has not reached the evaporation temperature target value (step ST2: NO), the refrigeration cycle device returns to step ST1. If the evaporation temperature has reached the evaporation temperature target value (step ST2: YES), the refrigeration cycle device proceeds to determine whether the evaporation temperature is lower than or equal to a compressor off value that is stored in advance (step ST3).

[0039] In a case where the evaporation temperature is higher than the compressor off-set value (step ST3: NO), the refrigeration cycle device continues the operation of the compressor (step ST4). In a case where the evaporation temperature is lower than or equal to the compressor off-set value (step ST3: YES), the refrigeration cycle device stops the operation of the compressor (step ST5). The evaporation temperature rises due to a stop of the operation of the compressor, and the refrigeration cycle device determines whether the evaporation temperature is higher than the compressor off-set value (hereinafter, the first condition) and whether a set period of time (e.g., three minutes), which is set in advance, has elapsed since the operation of the compressor stopped (hereinafter, the second condition) (step ST6).In a case where the refrigeration cycle device determines that at least one of the first and second conditions is not satisfied (step ST6: NO), the refrigeration cycle device returns to step ST5 and continues to stop the operation of the compressor. On the other hand, in a case where the refrigeration cycle device determines that both the first and second conditions are satisfied (step ST6: YES), the refrigeration cycle device returns to step ST1 and resumes normal control. This means that the refrigeration cycle device resumes the operation of the compressor and controls the operating frequency of the compressor such that the operating frequency is set to a value corresponding to the temperature difference between the evaporation temperature and the target evaporation temperature.

[0040] When operating the comparison example shown in Fig. As shown in Figure 5, the evaporating temperature changes in the following manner in a case where the outside air temperature drops below 0°C under low outside air conditions, for example, higher than or equal to -15°C and lower than 0°C, and the compressor is operated in a temperature environment (hereinafter, high-temperature controlled environment) in which the outside air temperature is higher than a compressor off-set value determined according to an evaporating temperature target value. This means that, first, the operation of the compressor during normal control causes the evaporating temperature to drop to the compressor off-set value (e.g., -15°C) or lower, and a thermal shutdown causes the compressor to stop operating.Thereafter, the evaporation temperature increases to the compressor off-set value over a period of time under the influence of the outside air temperature, and the compressor resumes operation when the preset time period elapses. Since the evaporation temperature changes as described above in a low outside air environment and a high-temperature controlled environment, the refrigeration cycle device is configured to keep the evaporation temperature lower than or equal to the target evaporation temperature, thereby maintaining the desired temperature inside the warehouse.

[0041] However, in a case where the outside air temperature drops below ultra-low outside air conditions of -15°C or, for example, equal to -25°C, and the compressor is operating in a temperature environment (hereinafter, low-temperature controlled environment) where the outside air temperature is lower than a compressor off-set value determined according to an evaporation temperature target value, the evaporation temperature changes as follows. This means that first, the operation of the compressor during normal control causes the evaporation temperature to drop to the compressor off-set value (e.g., -15°C) or lower, and then a thermal off causes the compressor to stop operating.Since the outside air temperature is lower than the compressor off-set value, the evaporation temperature does not rise to the compressor off-set value under the influence of the outside air temperature, and the compressor remains in a non-operating state. Thus, in a case where the refrigeration cycle device is used under ultra-low outside air conditions, and especially in a low-temperature controlled environment, the evaporation temperature does not rise to the compressor off-set value after it has dropped to the compressor off-set value or lower. This causes a problem in that the compressor does not resume operation and the temperature inside the bearing increases.

[0042] The aforementioned problem could be solved by pre-lowering the compressor off-set value, for example, to a temperature (e.g., -25°C) lower than or equal to the outside air temperature. This causes the evaporating temperature to easily rise to the compressor off-set value, and the compressor to easily resume operation. In other words, this prevents the compressor from resuming operation after the compressor has stopped. This setting allows the refrigeration cycle device to prevent the temperature inside the warehouse from rising. However, in a case where the compressor off-set value is lowered to a temperature lower than or equal to the outside air temperature, the compressor continues to operate until the evaporating temperature drops to the compressor off-set value.For this reason, the aforementioned solution may cause a problem of overcooling the inside of the bearing regardless of whether the current controlled environment is a low-temperature controlled environment or a high-temperature controlled environment.

[0043] According to Embodiment 1, even under such ultra-low outside air conditions and in such a low-temperature controlled environment as described above, control of a Fig. 7 below, the process is performed such that a desired temperature inside the warehouse is maintained by maintaining the evaporation temperature at the target evaporation temperature. The phrase "maintaining the evaporation temperature at the target evaporation temperature" here means that the evaporation temperature only needs to be maintained at a temperature lower than or equal to the target evaporation temperature, and is not limited to maintaining the evaporation temperature at the target evaporation temperature. The same applies to the phrase "maintaining a desired temperature inside the warehouse."

[0044] The below in Fig. The control shown in Figure 7 is performed in a case where the outside air temperature falls below the low outside air conditions. This evaluation is performed by the determination circuit 84 of the control device 8. The determination circuit 84 compares the outside air temperature detected by the outside air temperature sensor 5 with a low outside air condition threshold stored in the storage circuit 83, and determines that the outside air temperature falls below the low outside air conditions in a case where the outside air temperature is lower than the low outside air condition threshold. Once the determination circuit 84 determines that the outside air temperature falls below the low outside air conditions, the control device 8 performs the normal control of step ST11 of the Fig. 7. In a case where the outside air temperature has fallen out of the low outside air conditions, that is, in a case where the outside air temperature has become higher than or equal to the low outside air condition threshold, the control device 8 leaves the flowchart of the Fig. 7 and performs normal control which is carried out in a case where the outside air conditions fall under conditions (equivalent to “OTHER CONDITIONS” of the Fig. 8 below), which are different from the low outside air conditions and the ultra-low outside air conditions. This means that the controller 8 performs an operation of controlling the operating frequency of the compressor 1 so that the evaporating temperature reaches a target evaporating temperature, and performs thermo-turning and thermo-turning based on a compressor on-value and a compressor off-value for use in normal control.

[0045] Fig. 7 shows a control flowchart in the refrigeration cycle device according to the embodiment 1. A process of the Fig. The flowchart shown in Figure 7 is performed by the controller 8. In the following, the compressor off value represents a value for use in normal control unless otherwise described. Fig. Fig. 8 is an explanatory diagram showing examples of a compressor off value for use in a normal control and a compressor off value for use in an ultra-low outside air environment in a control of the Fig. 7. In Fig. 8, the label “OTHER CONDITIONS” indicates conditions other than ultra-low outside air conditions and low outside air conditions.

[0046] The operation control circuit 81 performs normal control based on the detected values ​​detected by the various sensors (step ST11). Here, the normal control is a normal control performed when the outside air temperature falls below the low outside air conditions. In this normal control, the operation control circuit 81 performs an operation of controlling the operating frequency of the compressor 1 so that the evaporation temperature reaches a target evaporation temperature, and performs thermo-on and thermo-off based on a compressor off value.That is, the operation control circuit 81 performs, as the normal control, a control of stopping the compressor 1 in a case where the evaporation temperature is lower than or equal to the compressor off-set value, and after stopping the operation of the compressor 1, resumes the operation of the compressor 1 in a case where the evaporation temperature of the evaporator is higher than the compressor off-set value and the set time period set in advance has elapsed. Here, a case will be described where the evaporation temperature target value is -5°C, the compressor off-set value is -15°C, and the ultra-low outside air condition threshold is -15°C.

[0047] During normal control, the conversion circuit 82 converts the intake pressure detected by the intake pressure sensor 6 into the evaporation temperature. The determination circuit 84 determines whether the evaporation temperature thus converted by the conversion circuit 82 has reached the evaporation temperature target value (step ST12). If the determination circuit 84 determines that the evaporation temperature has not reached the evaporation temperature target value (step ST12: NO), the operation control circuit 81 returns to step ST11. If the determination circuit 84 determines that the evaporation temperature has reached the evaporation temperature target value (step ST12: YES), the determination circuit 84 proceeds to determine whether the outside air temperature is lower than the ultra-low outside air low temperature threshold (step ST13).

[0048] In a case where the determination circuit 84 determines that the outside air temperature is lower than the ultra-low outside air low-temperature threshold (step ST13: YES), the determination circuit 84 proceeds and makes a determination of step ST14. This means that the determination circuit 84 determines whether the outside air temperature is lower than a low-temperature controlled ambient threshold (step ST14). The low-temperature controlled ambient threshold is the compressor off-value for use in normal control. The low-temperature controlled ambient threshold is not limited to the compressor off-value for use in normal control, but may be a compressor on-value for use in normal control.In other words, the low temperature controlled ambient threshold only needs to be a value that is lower than the evaporating temperature target and that is lower than the ultra-low outside air condition threshold.

[0049] In a case where the outside air temperature is lower than the low-temperature controlled ambient threshold (step ST14: YES), the operation control circuit 81 controls the compressor 1 in the following manner. This means that the operation control circuit 81 reduces the operating frequency of the compressor 1 to a minimum possible frequency during use, which is stored in advance in the memory circuit 83. Further, the operation control circuit 81 substitutes the compressor off-value for use in normal control with a compressor off-value for use in an ultra-low outside air environment and performs operation control (step ST15).

[0050] It should be noted that Fig. 8 shows an example where the compressor off value for use in normal control is -15°C, the compressor off value for use in an ultra-low outdoor air environment is -35°C, and the ultra-low outdoor air condition threshold is -15°C. In this way, the compressor off value for use in an ultra-low outdoor air environment is set to a temperature obtained by subtracting, for example, 20°C from the ultra-low outdoor air condition threshold. The compressor off value for use in an ultra-low outdoor air environment must be lower than an outdoor air temperature lower limit. The outdoor air temperature lower limit is a lower limit for the outdoor air temperature for use of the outdoor unit 10 and is a preset value.This means that the outside air temperature lower limit is a lower limit for the outside air temperature required for the refrigeration cycle device to operate safely without failure. The outside air temperature lower limit is a temperature (e.g., -25°C) lower than the ultra-low outside air condition threshold. The compressor off value for use in an ultra-low outside air environment simply needs to be a value lower than the outside air temperature lower limit, and any numerical value is available.

[0051] After step ST15, the determination circuit 84 determines whether the evaporation temperature is lower than or equal to the compressor off-set value for use in an ultra-low outside air environment (step ST16). If the determination circuit 84 determines that the evaporation temperature is higher than the compressor off-set value for use in an ultra-low outside air environment (step ST16: NO), the operation control circuit 81 continues operation of the compressor 1 at the minimum possible frequency (step ST17).

[0052] In a case where the determination circuit 84 determines in step ST16 that the evaporation temperature is lower than or equal to the compressor off-set value for use in an ultra-low outside air environment (step ST16: YES), the operation control circuit 81 stops the operation of the compressor 1 (step ST18). This means that in a case where the operation of the compressor 1 causes the evaporation temperature to drop to the compressor off-set value for use in an ultra-low outside air environment or lower, the operation control circuit 81 stops the operation of the compressor 1 (step ST18). Then, the determination circuit 84 determines whether the evaporation temperature is higher than the compressor off-set value for use in an ultra-low outside air environment (hereinafter, the first condition) and whether a set period of time, which is set in advance, has elapsed since the operation of the compressor 1 is stopped (hereinafter, the second condition) (step ST19).This set time period is, for example, three minutes, given, for example, the number of times compressor 1 starts and stops during its product lifetime.

[0053] In a case where the determination circuit 84 determines that at least one of the first condition and the second condition is not satisfied (step ST19: NO), the operation control circuit 81 returns to step ST18 and continues to stop the operation of the compressor 1. On the other hand, in a case where the determination circuit 84 determines that both the first condition and the second condition are satisfied (step ST19: YES), the operation control circuit 81 returns to step ST11 and resumes normal control.This means that the operation control circuit 81 resumes the operation of the compressor 1 and controls the operation frequency of the compressor 1 such that the operation frequency is set to a value corresponding to the temperature difference between the evaporating temperature and the evaporating temperature target value, and returns the compressor off value for use in an ultra-low outside air environment to the compressor off value for use in normal control.

[0054] This means that in a case where at least one of the first condition and the second condition is not satisfied in step ST19 (step ST19: NO), the operation control circuit 81 returns to step ST18 and continues to stop the operation of the compressor 1 (step ST18). On the other hand, in a case where both the first condition and the second condition are satisfied (step ST19: YES), the operation control circuit 81 returns to step ST11, resumes the operation of the compressor 1, and performs normal control.

[0055] It should be noted that the process in step ST19 could be replaced by a process of determining whether the evaporation temperature is higher than or equal to a first threshold, which will be described later. This means that if the evaporation temperature is lower than the first threshold, the process could return to step ST18, and if the evaporation temperature is higher than or equal to the first threshold, the process could return to step ST11. The first threshold only needs to be a value that is higher than the compressor off value for use in an ultra-low outside air environment and that is lower than the ultra-low outside air condition threshold.

[0056] Thus, when the refrigeration cycle device is used under ultra-low outside air conditions and in a low-temperature controlled environment, reducing the operating frequency of the compressor 1 to the minimum possible frequency makes it possible to prevent an excessive decrease in the evaporation temperature better than in a case where the operating frequency of the compressor 1 is not reduced to the minimum possible frequency. Furthermore, the refrigeration cycle device substitutes the compressor off-value for use in normal control with a compressor off-value for use in an ultra-low outside air environment. More specifically, this means that the refrigeration cycle device substitutes a compressor off-value of, for example, -15°C for use in normal control with a compressor off-value of, for example, -35°C for use in an ultra-low outside air environment.With this configuration, the refrigeration cycle device of Embodiment 1 simply allows the evaporation temperature to rise to the compressor off-state, as mentioned above, and simply allows the compressor 1 to resume operation. In other words, the refrigeration cycle device makes it possible to prevent the compressor 1 from continuing a stopped state without resuming operation. Therefore, when the refrigeration cycle device is used under ultra-low outside air conditions and in a low-temperature controlled environment, the refrigeration cycle device is configured to prevent the temperature inside a warehouse from rising and maintain the temperature inside the warehouse appropriately.

[0057] In a case where the determination circuit 84 determines in step ST14 that the outside air temperature is higher than or equal to the low-temperature controlled ambient threshold (step ST14: NO), the operation control circuit 81 performs the process in steps ST20 to ST23. The process in steps ST20 to ST23 is the same as the process in steps ST3 to ST6 of the comparative example. This means that the determination circuit 84 determines whether the evaporation temperature is lower than or equal to a compressor off-value (step ST20). Here, the compressor off-value is the compressor off-value for use in normal control. If the determination circuit 84 determines that the evaporation temperature is not lower than or equal to the compressor off-value (step ST20: NO), the operation control circuit 81 continues the operation of the compressor 1 (step ST21).On the other hand, when the determination circuit 84 determines that the evaporation temperature is lower than or equal to the compressor off value (step ST20: YES), the operation control circuit 81 stops the operation of the compressor 1 (step ST22).

[0058] After stopping the operation of the compressor 1, the determination circuit 84 determines whether the evaporation temperature is higher than the compressor off value for use in normal control (hereinafter, the third condition) and whether the set time period, which is set in advance, has elapsed since the compressor stopped (hereinafter, the fourth condition) (step ST23). In a case where the determination circuit 84 determines that at least one of the third and fourth conditions is not satisfied (step ST23: NO), the operation control circuit 81 returns to step ST22 and continues stopping the operation of the compressor 1. On the other hand, in a case where the determination circuit 84 determines that both the third and fourth conditions are satisfied (step ST23: YES), the operation control circuit 81 returns to step ST11 and resumes normal control.It should be noted that the process in step ST23 could be a process for determining whether the evaporation temperature is higher than or equal to a second threshold, which will be described later. This means that if the evaporation temperature is lower than the second threshold, the process could return to step ST22, and if the evaporation temperature is higher than or equal to the second threshold, the process could return to step ST11. The second threshold only needs to be a value higher than the compressor off value for use in normal control and lower than the evaporation temperature target value.

[0059] In a case where the determination circuit 84 further determines in step ST13 that the outside air temperature is also higher than or equal to the ultra-low outside air condition threshold (step ST13: NO), the operation control circuit 81 performs the process in steps ST20 to S23. This means that in a case where the outside air temperature falls below the low outside air conditions, the operation control circuit 81 performs control involving the use of the compressor off value for use in normal control, and is therefore configured to prevent the interior of the warehouse from being overcooled.

[0060] When reducing the operating frequency of compressor 1 to the minimum possible frequency in step ST15, operation control circuit 81 may adjust the operating frequency as follows. In a case where the difference between the intake pressure detected by intake pressure sensor 6 and the discharge pressure detected by discharge pressure sensor 7 is smaller than a predetermined value, that is, in a case where a compression ratio is low, operation control circuit 81 may adjust the minimum possible frequency to a value increased by, for example, 10 Hz. This adjustment enables the refrigeration cycle device to prevent a decrease in the compression ratio.

[0061] Although in the Fig. 7, the determination of step ST14 is further made by using the outside air temperature, the determination of step ST14 could be made by using the evaporation temperature target value or the compressor off-value, or could be made by using both. This means that the determination could be made in accordance with whether the evaporation temperature target value and / or the compressor off-value are lower than thresholds set separately in accordance with each of the values. In a case where the evaporation temperature target value is used, the determination is made in accordance with whether the evaporation temperature target value is less than, for example, -30°C. In a case where the compressor off-value is further used, the determination is made in accordance with whether the compressor off-value is less than, for example, -32°C.The compressor off value here is a compressor off value for use in normal control.

[0062] Fig. 9 is an explanatory diagram of a thermo-turn-on and a thermo-turn-off of the compressor under the ultra-low outside air conditions in the refrigeration cycle device according to Embodiment 1. Fig. 10 is an explanatory diagram of a thermo-switch-on and a thermo-switch-off of the compressor under the low outside air conditions in the refrigeration cycle device according to the embodiment 1. In both Fig. 9 and Fig. 10 the horizontal axis represents time [h] and the vertical axis represents temperature [°C]. (Ultra-low outdoor air conditions: Case in which an outdoor air temperature is -25 °C and falls under ultra-low outdoor air conditions)

[0063] As in Fig. 9, at time t1, when an actual evaporating temperature drops to a target evaporating temperature of -5°C, a determination is made as to whether the outside air conditions are ultra-low outside air conditions. Since the outside air temperature is -25°C and is lower than the ultra-low outside air condition threshold (-15°C), the compressor off value is lowered from -15°C to -35°C. Furthermore, if the actual evaporating temperature continues to drop and the actual evaporating temperature drops to -35°C or lower at time t2, the operation of compressor 1 is stopped. Thereafter, if the actual evaporating temperature increases and at time t3 the actual evaporating temperature is higher than -35°C and a set period of time that is set in advance elapses (not shown in Fig. 9), the operation of compressor 1 is resumed. (Low outdoor air conditions: Case where an outdoor air temperature is -10 °C and falls under low outdoor air conditions)

[0064] As in Fig. 10, at time t1, when an actual evaporating temperature drops to a target evaporating temperature of -5°C, a determination is made as to whether the outside air conditions are ultra-low outside air conditions. Since the outside air temperature here is -10°C, it is determined that the outside air conditions fall under low outside air conditions. If the actual evaporating temperature further drops and becomes lower than or equal to the compressor off value at time t2, the operation of compressor 1 is stopped. Thereafter, if the actual evaporating temperature increases and at time t3 the actual evaporating temperature is higher than the compressor off value and a set period of time that is set in advance elapses (not shown in Fig. 10), the operation of compressor 1 is resumed.

[0065] Although according to Embodiment 1, the condition for starting the operation of the flowchart of Embodiment 1 shown in Fig. 7, is a condition where the outside air temperature falls below the low outside air conditions, it could be the following condition. For example, the interior of the control device 8 or the outdoor unit 10 could be provided with an input unit, such as a switch, and it could be determined in view of a setting of the input unit whether the operation of the Fig. 7. This means more specifically that the cooling cycle device starts the operation of the Fig. 7 only in a case where the setting of the input unit is on and the outside air temperature falls below the low outside air conditions. On the other hand, in a case where the setting of the input unit is off, the refrigeration cycle device starts the operation of the Fig. 7, even if the outside air temperature falls below the low outside air conditions.

[0066] Furthermore, this input unit need not be limited to a switch, and an input signal could be obtained from a remote location through communication. Furthermore, the refrigeration cycle device could implement the operation of the flowchart of Embodiment 1 shown in Fig. 7 shown, only in a case where the input signal is on.

[0067] Furthermore, although the embodiment 1 exemplifies a refrigeration cycle device including a compressor 1 and a radiator 2 provided in an outdoor unit 10 as shown in Fig. 1, not necessarily be provided in an identical unit. The cooling circuit device could be as shown below in Fig. 11 shown.

[0068] Fig. 11 is a diagram showing another exemplary configuration of the refrigeration cycle device according to Embodiment 1. The refrigeration cycle device of Fig. 11 has a compressor 1 and a radiator 2 installed in separate units. More specifically, this means that the refrigeration cycle device includes a first outdoor unit 10A including the compressor 1 and a second outdoor unit 10B including the radiator 2. Furthermore, the first outdoor unit 10A and the second outdoor unit 10B are connected by an extension pipe 20a and an extension pipe 20b. Even if the refrigeration cycle device is configured as shown in Fig. As shown in Figure 11, it produces effects similar to those described above.

[0069] As described above, the control device 8 of the refrigeration cycle device of Embodiment 1 is a control device 8 of a refrigeration cycle device including a refrigerant circuit including a compressor 1 and an evaporator 4. The control device 8 includes an operation control circuit 81 configured to perform normal control of stopping the compressor 1 in a case where an evaporation temperature of the evaporator 4 is lower than or equal to a compressor off-value for use in normal control, which is an evaporation temperature set according to an evaporation temperature target value, and resuming operation of the compressor 1 in a case where the evaporation temperature of the evaporator 4 is higher than the compressor off-value and a set period of time set in advance elapses after stopping the operation of the compressor 1.The operation control circuit 81 performs normal control in a case where an outside air temperature falls below low outside air conditions that are set in advance. After the evaporation temperature reaches the evaporation temperature target value, and even in a case where the outside air temperature falls below ultra-low outside air conditions lower than the low outside air conditions and the outside air temperature is lower than a low-temperature controlled ambient threshold, or in a case where the outside air temperature falls below the ultra-low outside air conditions and the evaporation temperature target value and / or the compressor off value are lower than thresholds set separately in accordance with each of the values, the operation control circuit 81 is configured to substitute the compressor off value with a value lower than a preset outside air temperature lower limit.The threshold is a value that is lower than the evaporation temperature target value and that is lower than an ultra-low outside air condition threshold, which is a threshold for determining the ultra-low outside air conditions. After substituting the compressor off-value, the operation control circuit 81 continues the operation of the compressor 1 in a case where the evaporation temperature is higher than the thus-substituted compressor off-value. After substituting the compressor off-value, the operation control circuit 81 stops the operation of the compressor 1 in a case where the evaporation temperature is lower than or equal to the thus-substituted compressor off-value.After stopping the operation of the compressor 1, the operation control circuit 81 resumes the operation of the compressor 1 even in a case where both a first condition in which the evaporating temperature is higher than the thus-substituted compressor off-value and a second condition in which the set time period set in advance elapses after stopping the operation of the compressor 1 are satisfied, or in a case where the evaporating temperature is higher than or equal to a first threshold representing a temperature higher than the thus-substituted compressor off-value and lower than the ultra-low outside air condition threshold.The low temperature controlled ambient threshold is the compressor off value for use in normal control or a compressor on value for use in normal control that is higher than the compressor off value and that is lower than the evaporating temperature target value.

[0070] In this configuration, the control device 8 prevents the compressor 1 from resuming operation after stopping the operation of the compressor 1 under the ultra-low outside air conditions and in a low-temperature controlled environment. Therefore, the control device 8 is configured to prevent the temperature inside the warehouse from rising, making it possible to maintain a desired temperature inside the warehouse.

[0071] The operation control circuit 81 continues the operation of the compressor 1 in a case where the outside air temperature falls below the ultra-low outside air conditions and is higher than or equal to the low-temperature controlled ambient threshold and the evaporating temperature is higher than the compressor off value for use in the normal control.

[0072] With this configuration, the controller 8 performs an operation similar to that of the comparative example when the outside air temperature falls below ultra-low outside air conditions but is not in a low-temperature controlled environment. Therefore, the controller 8 is configured to better prevent the inside of the warehouse from being overcooled than when the compressor off value is substituted with a value lower than the outside air temperature lower limit, whether in a low-temperature controlled environment or a high-temperature controlled environment.

[0073] The operation control circuit 81 continues the operation of the compressor 1 in a case where the outside air temperature falls below the low outside air conditions and does not fall below the ultra-low outside air conditions and the evaporating temperature is higher than the compressor off value for use in the normal control.

[0074] With this configuration, the controller 8 performs an operation similar to that of the comparative example when the outside air conditions fall below the low outside air conditions and do not fall below the ultra-low outside air conditions. Therefore, the controller 8 is configured to better prevent the interior of the warehouse from being overcooled than in a case where the compressor off value is uniformly substituted with the value lower than the outside air temperature lower limit, regardless of whether the outside air conditions fall below the low outside air conditions or the ultra-low outside air conditions.

[0075] The operation control circuit 81 stops the operation of the compressor 1 even in a case where the outside air temperature falls below the ultra-low outside air conditions and is higher than or equal to the low-temperature controlled ambient threshold and the evaporating temperature is lower than or equal to the compressor off value for use in normal control, or in a case where the outside air temperature falls below the low outside air conditions and does not fall below the ultra-low outside air conditions and the evaporating temperature is lower than or equal to the compressor off value for use in normal control.After stopping the operation of the compressor 1, the operation control circuit 81 continues a state of stopping the operation of the compressor 1 even in a case where at least either a third condition in which the evaporating temperature is higher than the compressor off value for use in the normal control, or a fourth condition in which the set time period set in advance elapses after stopping the operation of the compressor 1 is not satisfied, or in a case where the evaporating temperature is lower than a second threshold which is higher than the compressor off value for use in the normal control and which is lower than the evaporating temperature target value.After stopping the operation of the compressor 1, the operation control circuit 81 returns the thus substituted compressor off value to the compressor off value for use in the normal control and resumes the normal control even in a case where both the third condition and the fourth condition are satisfied or in a case where the evaporation temperature is higher than or equal to the second threshold.

[0076] In this configuration, in a case where the evaporation temperature is lower than or equal to the compressor off value, the control device 8 is set to thermal shutdown and is configured to stop the operation of the compressor 1. Furthermore, the control device 8 is configured to separately perform control of continuing to stop the operation of the compressor 1 or control of returning to normal control according to the evaporation temperature after the operation is stopped.

[0077] When substituting the compressor off value with a value smaller than the outside air temperature lower limit, the operation control circuit 81 reduces an operation frequency of the compressor 1 to a minimum possible frequency during use and operates the compressor 1.

[0078] In this configuration, the control device 8 is arranged to prevent a decrease in the evaporation temperature better than in a case in which the operating frequency of the compressor 1 is not reduced to the minimum possible frequency.

[0079] When substituting the compressor off value with the value smaller than the outside air temperature lower limit, the operation control circuit 81 operates the compressor 1 while keeping an operation frequency of the compressor 1 fixed at an operation frequency at which the compressor 1 operates during normal control.

[0080] In this configuration, the control device 8 makes it possible to use a constant-velocity compressor as the compressor 1 in the refrigeration cycle device. Embodiment 2.

[0081] An embodiment 2 differs from the embodiment 1 in a control performed by the controller 8, and the difference in control makes the compressor 1 different in configuration from that of the embodiment 1. The following describes the embodiment 2 focusing on points of difference from the embodiment 1.

[0082] Fig. 12 shows a control flowchart in the refrigeration cycle device according to Embodiment 2. Steps of the process in Fig. 12, which are identical to those of the flow chart of the Fig. 7 of Embodiment 1 are assigned identical step numbers. In comparison with the flowchart of Fig.7 of Embodiment 1, Embodiment 2 differs only in that a step ST15 is replaced by a step ST15a. In step ST15a, the process of "REDUCING THE COMPRESSOR OPERATION FREQUENCY TO THE MINIMUM POSSIBLE FREQUENCY" of step ST15 is deleted. This means that when substituting the compressor off-time value for a compressor off-time value for use in an ultra-low outside air environment in step S15, the refrigeration cycle device of Embodiment 1 also performs the process of reducing the operation frequency of the compressor 1 to the minimum possible frequency and operates the compressor 1 at the minimum possible frequency.On the other hand, when substituting the compressor off-value for a compressor off-value for use in an ultra-low outside air environment in step ST15a, the refrigeration cycle device of Embodiment 2 does not change the compressor operating frequency and continues to operate at the compressor operating frequency maintained as it is during normal control. This means that the refrigeration cycle device of Embodiment 2 operates while keeping the operating frequency of the compressor 1 fixed.

[0083] With the configuration described above, the refrigeration cycle device of Embodiment 2 exhibits the following effect in addition to the effects similar to those of Embodiment 1. While a compressor whose operating frequency can be changed by inverter control is used in Embodiment 1, a constant speed compressor can be used as the compressor 1 in Embodiment 2.

[0084] Embodiments 1 and 2 are illustrative in all respects and are to be considered non-restrictive. The scope of the present disclosure is not limited to the foregoing description, but is shown by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and any changes to the scope of the claims. List of reference symbols

[0085] 1: Compressor, 2: Radiator, 3: Expansion valve, 4: Evaporator, 5: Outside air temperature sensor, 6: Intake pressure sensor, 7: Discharge pressure sensor, 8: Control device, 10: Outdoor unit, 10A: First outdoor unit, 10B: Second outdoor unit, 11: Indoor unit, 20a: Extension pipe, 20b: Extension pipe, 80: Processing circuit, 80a: Processor, 80b: Memory, 81: Operation control circuit, 82: Converter circuit, 83: Storage circuit, 84: Determination circuit, 85: Calculation circuit, A: Refrigerant circuit QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-66068

[0003]

Claims

[1] A control device of a refrigeration cycle device comprises a refrigerant circuit having a compressor and an evaporator, the control device having an operation control circuit configured to perform normal control of stopping the compressor in a case where an evaporation temperature of the evaporator is lower than or equal to a compressor off-temperature for use in normal control, which is an evaporation temperature set according to an evaporation temperature target value, and resuming operation of the compressor in a case where the evaporation temperature of the evaporator is higher than the compressor off-value and a set period of time, which is set in advance, elapses after stopping the compressor, wherein the operation control circuit is arranged to perform the normal control in a case where an outside air temperature falls below low outside air conditions which are set in advance, wherein, after the evaporation temperature reaches the evaporation temperature target value and either in a case where the outside air temperature falls below ultra-low outside air conditions that are lower than the low outside air conditions and the outside air temperature is lower than a low-temperature controlled ambient threshold or in a case where the outside air temperature falls below the ultra-low outside air conditions and the evaporation temperature target value and / or the compressor off value are lower than thresholds that are separately set in accordance with each of the values, the operation control circuit is configured to substitute the compressor off value with a value that is lower than an outside air temperature lower limit that is set in advance, wherein the low-temperature controlled ambient threshold is a value that is lower than the evaporation temperature target value and that is lower than an ultra-low outside air condition threshold, which is a threshold for determining the ultra-low outside air conditions, wherein the operation control circuit is arranged, after substituting the compressor off-value, to continue the operation of the compressor in a case where the evaporation temperature is higher than the thus substituted compressor off-value, wherein the operation control circuit is arranged, after substituting the compressor off-value, to stop the operation of the compressor in a case where the evaporation temperature is lower than or equal to the thus substituted compressor off-value, wherein the operation control circuit is configured to resume the operation of the compressor after stopping the operation of the compressor either in a case where both a first condition in which the evaporating temperature is higher than the thus substituted compressor off-value and a second condition in which the set time period set in advance elapses after stopping the operation of the compressor are satisfied, or in a case where the evaporating temperature is higher than or equal to a first threshold representing a temperature higher than the thus substituted compressor off-value and lower than the ultra-low outside air condition threshold. [2] The control device of the refrigeration cycle device according to claim 1, wherein the low-temperature controlled ambient threshold is the compressor off-value for use in normal control or a compressor on-value for use in normal control that is larger than the compressor off-value and that is smaller than the evaporating temperature target value. [3] The control device of the refrigeration cycle device according to claim 1 or 2, wherein the operation control circuit is configured to continue the operation of the compressor in a case where the outside air temperature falls below the ultra-low outside air conditions and is higher than or equal to the low-temperature controlled ambient threshold and the evaporating temperature is higher than the compressor off value for use in the normal control. [4] The control device of the refrigeration cycle device according to any one of claims 1 to 3, wherein the operation control circuit is arranged to continue the operation of the compressor in a case where the outside air temperature falls below the low outside air conditions and does not fall below the ultra-low outside air conditions and the evaporating temperature is higher than the compressor off value for use in the normal control. [5] Control device of the refrigeration cycle device according to one of claims 1 to 4, wherein the operation control circuit is configured to stop the operation of the compressor either in a case where the outside air temperature falls below the ultra-low outside air conditions and is higher than or equal to the low-temperature controlled ambient threshold and the evaporating temperature is less than or equal to the compressor off value for use in normal control, or in a case where the outside air temperature falls below the low outside air conditions and does not fall below the ultra-low outside air conditions and the evaporating temperature is less than or equal to the compressor off value for use in normal control, after stopping the operation of the compressor, the operation control circuit is configured to continue a state of stopping the operation of the compressor either in a case where at least one of a third condition in which the evaporation temperature is higher than the compressor off-value for use in normal control and a fourth condition in which the set time period, which is set in advance, elapses after stopping the operation of the compressor is not met, or in a case where the evaporation temperature is lower than a second threshold which is higher than the compressor off-value for use in normal control and which is lower than the evaporation temperature target value, and the operation control circuit is arranged, either in a case where both the third condition and the fourth condition are met or in a case where the evaporation temperature is greater than or equal to the second threshold, to reset the thus substituted compressor off value to the compressor off value for use in the normal control and to resume the normal control. [6] The control device of the refrigeration cycle device according to any one of claims 1 to 5, wherein, upon substituting the compressor off value with the value smaller than the outside air temperature lower limit, the operation control circuit is configured to reduce an operation frequency of the compressor to a minimum possible frequency during use and operate the compressor. [7] The control device of the refrigeration cycle device according to any one of claims 1 to 5, wherein, in substituting the compressor off value with the value smaller than the outside air temperature lower limit, the operation control circuit is configured to operate the compressor while keeping an operation frequency of the compressor fixed at an operation frequency at which the compressor is operated during normal control. [8] Outdoor unit which has: the control device of the refrigeration cycle device according to one of claims 1 to 7; and the compressor. [9] An outdoor unit according to claim 8 as dependent on claim 7, wherein the compressor is a constant speed compressor. [10] Cooling circuit device comprising: the control device of the refrigeration cycle device according to one of claims 1 to 7; the compressor; a radiator; an expansion valve; and the evaporator.

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