WO2025041232A1 - Refrigeration cycle device and control method for refrigeration cycle device - Google Patents

Abstract

A refrigeration cycle device (1) comprises a heat source machine (10), a plurality of indoor units (3), a control device (300), and a plurality of temperature sensors (4). The control device (300) determines the number of operating indoor units to be operated, on the basis of a plurality of first difference values between a detected temperature of each of the plurality of indoor units (3) and a set temperature that corresponds to the detected temperature. The control device (300) determines the number of operating indoor units as the operating indoor units. The control device (300) operates the operating indoor units.

Description

Refrigeration cycle device and method for controlling the refrigeration cycle device

This disclosure relates to a refrigeration cycle device and a method for controlling a refrigeration cycle device.

For example, Japanese Patent Application Laid-Open Publication No. 10-9689 discloses a refrigeration unit. This refrigeration unit has an indoor unit, a heat source unit, and the like. This refrigeration unit stores a set temperature and detects the indoor temperature of the indoor unit. Then, when the indoor temperature is higher than the detected temperature, the refrigeration unit performs cooling by the indoor unit (performs thermo ON control). On the other hand, when the indoor temperature is lower than the detected temperature, the refrigeration unit stops cooling by the indoor unit (performs thermo OFF control).

Japanese Patent Application Publication No. 10-9689

For example, there are so-called multi-air conditioners in which multiple indoor units are connected to one heat source unit. A refrigeration cycle device can be considered in which the above-mentioned refrigeration unit technology is applied to such a multi-air conditioner. However, in this refrigeration cycle device, the thermo-ON timing and thermo-OFF timing of the multiple indoor units depend on the indoor temperatures of the multiple indoor units. Therefore, in this refrigeration cycle device, the number of indoor units for which thermo-ON control is executed may become excessively large. In this case, the capacity of the heat source unit may become excessive, and the coefficient of performance (COP) of the refrigeration cycle device may decrease.

The objective of this disclosure is to provide a refrigeration cycle device that improves the coefficient of performance, and a method for controlling a refrigeration cycle device.

The refrigeration cycle device according to this embodiment includes a heat source unit, a plurality of indoor units, a control unit, and a plurality of temperature sensors. The heat source unit has a compressor that discharges a refrigerant. The control unit has a memory that stores the set temperature of each of the plurality of indoor units. The plurality of temperature sensors detect the temperature of each room in which each of the plurality of indoor units is installed as a detected temperature. The control unit executes a first process of determining the number of indoor units to be operated among the plurality of indoor units based on the detected temperature of each of the plurality of indoor units and a plurality of first difference values between the detected temperature and the corresponding set temperature. The control unit executes a second process of determining the indoor units of the operating number from the plurality of indoor units as operating indoor units. The control unit then executes a third process of operating the operating indoor units.

The control method disclosed herein is a method for controlling a refrigeration cycle device. The refrigeration cycle device includes a heat source unit, a plurality of indoor units, a control unit, and a plurality of temperature sensors. The heat source unit has a compressor that discharges a refrigerant. The control unit has a memory that stores the set temperatures of the plurality of indoor units. The plurality of temperature sensors detect the temperature of each room in which each of the plurality of indoor units is installed as a detected temperature. The control method includes determining the number of indoor units to be operated among the plurality of indoor units based on the detected temperature of each of the plurality of indoor units and a plurality of first difference values between the detected temperature and the corresponding set temperature. The control method includes determining the operating number of indoor units from the plurality of indoor units as operating indoor units. The control method then includes operating the operating indoor units.

This disclosure makes it possible to improve the coefficient of performance.

1 is a diagram showing a configuration example of a refrigeration cycle device according to the present disclosure. FIG. 2 is a functional block diagram of a control device. 4 is a flowchart showing main processing of a control device. 4 is a main flowchart of a number-of-vehicles process according to the first embodiment. FIG. 11 is a diagram showing changes in room temperature in each room in a refrigeration cycle device of a comparative example. 4 is a diagram showing changes in room temperature of each room in the refrigeration cycle device of the present embodiment. FIG. 1 is a diagram showing changes in ΔT of five chambers 51 to 55 in the refrigeration cycle device of the present embodiment. FIG. FIG. 13 is a diagram showing the relationship between the number of thermo-ON units and the coefficient of performance. 13 is a main flowchart of the number processing according to the second embodiment.

Below, the embodiments of the present invention will be described in detail with reference to the drawings. Several embodiments will be described below, but it is planned from the beginning of the application that the configurations described in each embodiment will be appropriately combined. Note that the same or corresponding parts in the drawings will be given the same reference numerals and their description will not be repeated.

Embodiment 1.
Fig. 1 is a diagram showing a refrigerant circuit of a refrigeration cycle apparatus 1 according to the first embodiment. Referring to Fig. 1, the refrigeration cycle apparatus 1 includes a heat source unit 2 and N indoor units (N is an integer equal to or greater than 2). The N indoor units are also referred to as indoor units 31 to 3N. The indoor units 31 to 3N are disposed in chambers 51 to 5N, respectively. Furthermore, the refrigeration cycle apparatus 1 includes pipes 89, 90, 92, 94, 96, 97, 98, and 99. The refrigeration cycle apparatus 1 is capable of performing cooling operation and heating operation according to settings made by a user or the like.

The heat source unit 2 includes a compressor 10, an outdoor heat exchanger 40, an outdoor fan 61, a four-way valve 100, and a control device 300. The indoor units 31 to 3N include indoor fans 211 to 21N, indoor heat exchangers 201 to 20N, and electronic expansion valves (LEV: Linear Expansion Valves) 111 to 11N, respectively. Note that below, the indoor units 31 to 3N, the indoor fans 211 to 21N, the indoor heat exchangers 201 to 20N, and the electronic expansion valves 111 to 11N are also collectively referred to as the indoor unit 3, the indoor fan 21, the indoor heat exchanger 20, and the electronic expansion valve 11, respectively.

Tube 89 connects port H of four-way valve 100 to the gas side refrigerant pipe connection port of heat source unit 2. Tube 90 connects the gas side refrigerant pipe connection port of heat source unit 2 to ports P11 to P1N of indoor heat exchangers 201 to 20N, respectively.

Tube 92 connects the liquid side refrigerant pipe connection port of the heat source unit 2 to the electronic expansion valves 111-11N. Tube 94 connects the liquid side refrigerant pipe connection port of the heat source unit 2 to port P3 of the outdoor heat exchanger 40. Tube 96 connects port P4 of the outdoor heat exchanger 40 to port F of the four-way valve 100. Tube 98 connects the refrigerant inlet 10a of the compressor 10 to port E of the four-way valve 100. Tube 99 is connected between the refrigerant outlet 10b of the compressor 10 and port G of the four-way valve 100.

Inside the indoor units 31-3N, the indoor heat exchangers 201-20N are connected to the electronic expansion valves 111-11N, respectively.

The control device 300 controls the compressor 10, the four-way valve 100, the electronic expansion valve 11, the outdoor fan 61, the indoor fan 21, etc., in response to the outputs of various sensors and operation command signals transmitted from a remote controller or the like. The remote controller is operated by a user or the like. Note that in the example of FIG. 1, it is described that temperatures T1 to TN detected by each of the temperature sensors 41 to 4N (temperature sensor 4) are input to the control device 300. Also, in the example of FIG. 1, it is shown that the control device 300 outputs control signals to the compressor 10 and each of the electronic expansion valves 111 to 11N (electronic expansion valve 11).

The control device 300 includes a CPU (Central Processing Unit) 301, a memory 302, a communication interface 303, etc. The memory 302 has, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). Note that the control of the control device 300 is not limited to processing by software, but can also be processed by dedicated hardware (electronic circuitry).

The compressor 10 compresses the refrigerant drawn in from the refrigerant inlet 10a. The compressor 10 then discharges the compressed refrigerant from the refrigerant outlet 10b. The compressor 10 is configured to change its operating frequency according to a control signal received from the control device 300. The output of the compressor 10 is adjusted by changing the operating frequency of the motor of the compressor 10. Various types of compressors 10 can be used, for example, a rotary type, a reciprocating type, a scroll type, and a screw type.

For example, during cooling operation, the control device 300 controls the operating frequency of the compressor 10 so that the evaporation temperature of the refrigerant (ET: Evaporating Temperature) reaches a predetermined target value. The predetermined target value of the evaporation temperature is, for example, 0 degrees. Furthermore, during heating operation, the control device 300 controls the operating frequency of the compressor 10 so that the condensation temperature of the refrigerant (CT: Condensation Temperature) reaches a predetermined target value. The predetermined target value of the condensation temperature is, for example, 45 degrees.

The four-way valve 100 is controlled to be in either state A (cooling operation state) or state B (heating operation state) by a control signal received from the control device 300. State A is a state in which port E and port H are connected, and port F and port G are connected. State B is a state in which port E and port F are connected, and port H and port G are connected. By operating the compressor 10 in state A (cooling operation state), the refrigerant circulates through the refrigerant circuit in the direction indicated by the solid arrow. Also, by operating the compressor 10 in state B (heating operation state), the refrigerant circulates through the refrigerant circuit in the direction indicated by the dashed arrow.

The opening of the electronic expansion valve 11 is controlled by a control signal received from the control device 300 to either fully open, perform SH (superheat: degree of superheat, Super Heat) control, SC (subcool: degree of subcooling, Sub Cool) control or close (fully closed).

During cooling operation, the control device 300 adjusts the opening of the electronic expansion valve 11 so that the SH of the refrigerant outlet of the indoor unit 3 reaches a predetermined target value. Also, during heating operation, the control device 300 adjusts the opening of the electronic expansion valve 11 so that the subcooling of the refrigerant outlet of the indoor unit 3 reaches a predetermined target value. The predetermined target value is, for example, 3 degrees. Note that sensors for detecting superheat and subcooling are not shown in FIG. 1.

The temperature sensors 41 to 4N detect the indoor temperatures of rooms 51 to 5N as detected temperatures T1 to TN, respectively. In the example of FIG. 1, the temperature sensors 41 to 4N are shown installed in the indoor units 31 to 3N, respectively. However, the temperature sensors 41 to 4N may be installed in other locations as long as they can detect the indoor temperatures of rooms 51 to 5N. The temperature sensors 41 to 4N may be installed outside the indoor units 31 to 3N, respectively. The temperature sensors 41 to 4N may also be installed in the remote controllers corresponding to the indoor units 31 to 3N, respectively.

The fan rotation speed of the indoor fan 21 is driven by a control signal received from the control device 300. The fan rotation speed is controlled at a fixed value designed to balance energy saving and noise.

The control of allowing at least a portion of the refrigerant compressed and discharged from the compressor 10 to flow into the indoor heat exchanger 20 by opening the electronic expansion valve 11 or the like is also referred to as "first control". The first control is also referred to as "thermo-ON control". The thermo-ON control corresponds to "control for operating the indoor unit" in this disclosure. In addition, the control of not allowing the refrigerant compressed and discharged from the compressor 10 to flow into the indoor heat exchanger 20 by blocking the electronic expansion valve 11 or the like is also referred to as "second control". The first control is also referred to as "thermo-OFF control". The thermo-OFF control corresponds to "control for stopping operation of the indoor unit" in this disclosure.

The control device 300 performs thermo-ON and thermo-OFF (first control and second control) for each indoor unit 31-3N by operating the compressor 10 (operating frequency of the compressor 10), opening and closing (adjusting the opening degree) the electronic expansion valves 111-11N, and driving the indoor fans 211-21N.

[Functional block diagram of the control device 300]
Fig. 2 is a functional block diagram of the control device 300. The control device 300 has a receiving unit 312, a processing unit 314, a storage unit 316, and a transmitting unit 318. The receiving unit 312 and the transmitting unit 318 correspond to the communication interface 303 in Fig. 1. The processing unit 314 corresponds to the CPU 301. The storage unit 316 corresponds to the memory 302.

As described above, temperature sensors 41-4N detect the temperatures of chambers 51-5N as detected temperatures T1-TN, respectively. The detected temperatures T1-TN are input to the control device 300, and the receiving unit 312 of the control device 300 receives the detected temperatures T1-TN. The detected temperatures T1-TN are output to the processing unit 314.

The memory unit 316 stores the set temperatures Ts1 to TsN of the indoor units 31 to 3N. The set temperatures Ts1 to TsN are set, for example, by a user (such as the administrator of the refrigeration cycle device 1). The "previous ΔTa" stored in the memory unit 316 will be described later.

The processing unit 314 executes unit number processing and determination processing so as to improve the COP of the refrigeration cycle device 1. The unit number processing is a process for determining the number of indoor units 3 (operating number) to be operated (thermo-ON). The "operating number" is also referred to as the "thermo-ON number". The processing unit 314 executes the unit number processing for each first cycle. In this embodiment, the first cycle is "3 minutes" as shown in step S2 of FIG. 3 described below.

The determination process is a process for determining which indoor units will have their thermostats turned ON, based on the number of units with their thermostats turned ON determined by the unit count process. The processing unit 314 executes the determination process for each second cycle. In this embodiment, the second cycle is shorter than the first cycle, and is "1 minute" as shown in step S6 in FIG. 3, which will be described later.

[flowchart]
FIG. 3 is a flowchart showing the main processing of the control device 300. The flowchart in FIG. 3 is executed, for example, periodically (for example, every second). First, in step S2, the control device 300 judges whether or not three minutes (first cycle) have passed since the previous (most recent) execution of the number processing. If three minutes have not passed since the previous execution of the number processing (NO in step S2), the processing in FIG. 3 ends. If three minutes have passed since the previous (most recent) execution of the number processing, the processing proceeds to step S4. In step S4, the control device 300 determines the number S of thermo-ON devices. Details of step S4 will be described later with reference to FIG. 4.

Next, in step S6, the control device 300 determines whether one minute (second cycle) has passed since the previous (most recent) execution of the decision process. If one minute has not passed since the previous (most recent) execution of the decision process (NO in step S6), the process in FIG. 3 ends. If one minute has passed since the previous (most recent) execution of the decision process, the process proceeds to step S8.

In step S8, the control device 300 executes a determination process. Specifically, the control device 300 determines the number S of indoor units with the thermo-ON determined by the number process in step S4. In this embodiment, the control device 300 executes a determination process in which, from the N indoor units 3, the S indoor units with the larger first difference value ΔT are determined as the "operating indoor units 3s". The "operating indoor units 3s" are indoor units that will have their thermo-ON. The difference value ΔT will be described later.

Next, in step S10, the control device 300 actually operates the operating indoor unit 3s determined in step S8 (executes thermo-ON control for the operating indoor unit). Specifically, in step S10, the control device 300 executes a process to control the operating frequency of the motor of the compressor 10 so that the refrigerant pressure (refrigerant evaporation pressure) of the operating indoor unit 3s becomes a predetermined value.

Here, the predetermined value will be explained. For example, during cooling operation, the refrigerant pressure at which the evaporation temperature of the refrigerant corresponds to a first predetermined temperature (for example, 0 degrees) is set as the predetermined value. The control device 300 may also predict the heat load based on predetermined parameters (such as outside air temperature), and if the heat load is small, the refrigerant pressure at which the evaporation temperature corresponds to a higher evaporation temperature (for example, 10 degrees) may be set as the predetermined value. During heating operation, the refrigerant pressure at which the condensation temperature corresponds to a second predetermined temperature (for example, 45 degrees) is set as the predetermined value. The heat load may also be predicted based on the above-mentioned predetermined parameters, and if the heat load is expected to be small, the refrigerant pressure at which the condensation temperature corresponds to a second predetermined temperature (for example, 40 degrees) may be set as the predetermined value.

In addition, in step S10, the control device 300 adjusts the opening degree of the electronic expansion valve 11s of the operating indoor unit 3s and drives the indoor fan 21s of the operating indoor unit 3s.

FIG. 4 is a main flowchart of the number processing in step S4. In step S22, the control device 300 identifies the number S of units with the thermo ON at the present time. To identify the number S of units with the thermo ON, for example, the control device 300 stores the indoor unit ID (identification) of the indoor unit whose thermo is ON in the RAM of the memory 302. Then, in step S22, the number S of units with the thermo ON is identified by checking the indoor unit ID in the RAM. Note that the number S of units with the thermo ON identified in step S22 corresponds to the "number of indoor units currently operating" in this disclosure.

Next, in step S24, the control device 300 acquires the detected temperatures T1 to TN of all N indoor units 31 to 3N from the temperature sensors 41 to 4N. Next, in step S26, the processing unit 314 calculates multiple first difference values ΔTa1 to ΔTaN between the acquired detected temperatures T1 to TN and the set temperatures Ts1 to TsN corresponding to the detected temperatures. Specifically, the processing unit 314 calculates the first difference value ΔTa1 between the detected temperature T1 and the set temperature Ts1, calculates the first difference value ΔTa2 between the detected temperature T2 and the set temperature Ts2, . . . and calculates the first difference value ΔTaN between the detected temperature TN and the set temperature TsN.

Here, the calculation of the first difference value will be described in detail. When the refrigeration cycle device 1 is performing cooling operation, the first difference values ΔTa1 to ΔTaN are values obtained by subtracting the set temperature from the detected temperature. When the refrigeration cycle device 1 is performing heating operation, the first difference values ΔTa1 to ΔTaN are values obtained by subtracting the detected temperature from the set temperature.

Furthermore, the control device 300 calculates the average value ΔTa of the first difference values ΔTa1 to ΔTaN. In other words, during cooling operation, the processing unit 314 calculates the average value ΔTa using the following formula (1).

Note that during heating operation, the numerator on the right side of the above formula (1) becomes "Tsn-Tn". Furthermore, in step S26, each time the control device 300 calculates the average value ΔTa, the control device 300 stores the average value ΔTa in the memory unit 316 as the previous average value ΔTa (see FIG. 2). When the process of step S26 ends, the process proceeds to step S28.

Next, the processing of step S28 will be described. The average value ΔTa is a value indicating the overall deviation (difference) of the N indoor units 3 between the current temperature (detected temperature) and the set temperature. If this average value ΔTa is gradually increasing, it means that the deviation is increasing, so it is preferable to increase the number of thermo-ON units to reduce the deviation. On the other hand, if this average value ΔTa is gradually decreasing, it means that the deviation is decreasing, so it is preferable to decrease the number of thermo-ON units to reduce power consumption.

The specific processing of step S28 will be described below. In step S28, the processing unit 314 calculates a difference value by subtracting the "average value ΔTa calculated previously" from the "average value ΔTa calculated currently". This difference value corresponds to the "second difference value" of the present disclosure. In addition, in the following processing, a first threshold value Th1 and a second threshold value Th2 that are defined in advance are used. The first threshold value Th1 is a positive value, and the second threshold value Th2 is a negative value.

When this second difference value is greater than the first threshold value Th1, this means that the average value ΔTa calculated this time is greater than the average value ΔTa calculated last time (the deviation degree has increased). Therefore, the control device 300 increases the number of thermo-ON units to reduce the deviation degree.

On the other hand, if this second difference value is smaller than the second threshold value Th2, this means that the average value ΔTa calculated this time is smaller than the average value ΔTa calculated previously (the deviation degree is reduced). Therefore, the control device 300 reduces the number of thermo-ON devices to reduce power consumption.

Furthermore, in steps S28 and S32, the control device 300 uses the average value ΔTa calculated this time. Specifically, it determines whether the average value ΔTa is positive or negative. In general, it is preferable that the average value ΔTa is closer to "0". Therefore, when the average value ΔTa calculated this time is positive, the number of devices with the thermo ON is increased to bring the average value ΔTa closer to "0". On the other hand, when the average value ΔTa calculated this time is negative, the number of devices with the thermo ON is decreased to reduce power consumption and bring the average value ΔTa closer to "0".

In light of the above explanation, in step S28, the control device 300 determines whether the second difference value is greater than the first threshold value Th1 and ΔTa is positive. If the answer is YES in step S28, that is, if the second difference value is greater than the first threshold value Th1 and ΔTa is positive, the process proceeds to step S30. On the other hand, if the answer is NO in step S28, the process proceeds to step S32.

In step S32, the control device 300 determines whether the second difference value is smaller than the second threshold value Th2 and ΔTa is negative. If step S32 is YES, that is, if the second difference value is smaller than the second threshold value Th2 and ΔTa is negative, the process proceeds to step S34. On the other hand, if step S32 is NO, the process of step S4 ends.

In step S30, the control device 300 determines the number of thermo-ON devices S to be a value calculated by increasing the current number of thermo-ON devices S (the number of thermo-ON devices S identified in step S22) by one. In step S32, the control device 300 determines the number of thermo-ON devices S to be a value calculated by decreasing the current number of thermo-ON devices S (the number of thermo-ON devices S identified in step S22) by one. The process of step S30 corresponds to the "first number process" of this disclosure. The process of step S32 corresponds to the "second number process" of this disclosure. In addition, if the answer is NO in step S32, the control device 300 determines not to change the current number of thermo-ON devices S. This decision corresponds to the "third number process" of this disclosure.

[Effects of the refrigeration cycle device of this embodiment]
Next, a simulation result for explaining the effect of the refrigeration cycle device 1 of the present embodiment will be described. In the following, a refrigeration cycle device to which the idea described in JP-A-10-9689 is applied to a so-called multi-air conditioner in which multiple indoor units are connected to one heat source unit is also referred to as a "comparative refrigeration cycle device". FIG. 5 is a diagram showing the change in room temperature of each room and the change in the number of thermo-ON units in the comparative refrigeration cycle device. FIG. 6 is a diagram showing the change in room temperature of each room and the change in the number of thermo-ON units in the refrigeration cycle device 1 of the present embodiment.

Next, the capacity of the refrigeration cycle device 1 applied in the simulation will be explained. In this simulation result, a case where cooling operation is performed by the refrigeration cycle device 1 will be explained. Furthermore, the number of indoor units is "five", and the five indoor units are arranged in the five corresponding rooms. That is, in the example of FIG. 1, indoor units 31 to 35 are arranged in rooms 51 to 55, respectively. The capacity of all five indoor units is standardized at 4.5 kW. The loads of the five rooms are 2 kW, 2.5 kW, 3 kW, 3.5 kW, and 4 kW, respectively. The set temperature of the five indoor units is 27 degrees, and the initial temperature of the five rooms is 27 degrees.

In the refrigeration cycle device of the comparative example, the control device executes thermo OFF control when the detected temperature (room temperature) reaches a temperature 0.5 degrees lower than the set temperature (i.e., the detected temperature reaches 26.5 degrees). In the refrigeration cycle device of the comparative example, the control device executes thermo ON control when the detected temperature (room temperature) reaches a temperature 0.5 degrees higher than the set temperature (i.e., the detected temperature reaches 27 degrees). The first and second cycles in the refrigeration cycle device 1 of this embodiment are 3 minutes and 1 minute, respectively.

The upper parts of Figures 5(A)-(E) and Figures 6(A)-(E) respectively show the thermo-ON and thermo-OFF states of each indoor unit in rooms 51-55. The lower parts of Figures 5(A)-(E) and Figures 6(A)-(E) show the room temperatures in rooms 51-55. Figures 5(F) and 6(F) show the change in the number of units with the thermo-ON. The horizontal axis of Figures 5(A)-(F) and Figures 6(A)-(F) shows time.

As shown in FIG. 5(F), in the refrigeration cycle device of the comparative example, the number of thermo-ON units varies within a range of 0 to 5 units. In this way, the range of variation in the number of thermo-ON units is large in the refrigeration cycle device of the comparative example. The reason for this variation depends on the indoor temperatures of the multiple indoor units, so the control device executes thermo-ON and thermo-OFF for each indoor unit independently. Therefore, the thermo-ON timing and thermo-OFF timing of each indoor unit are accidental and follow the flow. Therefore, in the refrigeration cycle device of the comparative example, the number of thermo-ON units may be excessive, in which case the instantaneous capacity of the heat source unit may become excessive, and the coefficient of performance of the refrigeration cycle device may decrease.

On the other hand, as shown in FIG. 6 (F), in the refrigeration cycle apparatus 1 of this embodiment, the number of thermo-ON units can be changed in increments of three or four units. In this way, the refrigeration cycle apparatus 1 of this embodiment can reduce the maximum value of the number of thermo-ON units and the range of change in the number of thermo-ON units compared to the refrigeration cycle apparatus of the comparative example. This is because the refrigeration cycle apparatus 1 of this embodiment executes thermo-ON control based on the first difference in all of the multiple indoor units.

FIG. 7 is a diagram showing changes in ΔT for chambers 51 to 55 in the refrigeration cycle device 1 of this embodiment. FIGS. 7(A) to 7(E) show changes in the first difference values ΔTa1 to ΔTa5 for chambers 51 to 55, respectively. FIG. 7(F) shows changes in the average value ΔTa of the first difference values. FIG. 7(G) shows changes in the number of thermo-ON units, and is a diagram similar to FIG. 6(F).

In general, when the number of indoor units with the thermostat turned on is small, the refrigerant circulating flow rate passing through the outdoor heat exchanger 40 of the heat source unit 2 can be reduced, and the heat transfer area of the outdoor heat exchanger 40 of the heat source unit 2 can be increased relative to the refrigerant circulating flow rate. Therefore, when the number of indoor units with the thermostat turned on is small, the coefficient of performance of the refrigeration cycle device 1 can be improved more than when the number of indoor units with the thermostat turned on is large.

FIG. 8 is a diagram showing the relationship between the number of thermo-ON units and the coefficient of performance (COP). In the example of FIG. 8, the vertical axis indicates the coefficient of performance, and the horizontal axis indicates the number of thermo-ON units. As described above, the example of FIG. 8 shows that when the number of indoor units with thermo-ON is small, the coefficient of performance of the refrigeration cycle device 1 is improved more than when the number of indoor units with thermo-ON is large. Generally, as shown in FIG. 8, there is a tendency for the improvement in COP to slow down (saturate) as the number of indoor units with thermo-ON decreases. Therefore, the average COP of the refrigeration cycle device 1 of this embodiment, in which the fluctuation range of the number of thermo-ON units is small, is higher than the average COP of the refrigeration cycle device of the comparative example, in which the fluctuation range of the number of thermo-ON units is large.

As described above, the refrigeration cycle device 1 of this embodiment can reduce the maximum number of thermo-ON units more than the refrigeration cycle device of the comparative example, and therefore can reduce the instantaneous capacity of the heat source unit 2. Therefore, the refrigeration cycle device 1 of this embodiment can improve the coefficient of performance more than the refrigeration cycle device of the comparative example. In addition, the refrigeration cycle device 1 of this embodiment can reduce the fluctuation range of the number of thermo-ON units more than the refrigeration cycle device of the comparative example, and therefore can improve the coefficient of performance more than the refrigeration cycle device of the comparative example.

[Summary]
(1) As described above, the control device 300 executes the first process (the number process in step S4 in FIG. 3). The first process is a process for determining the number of indoor units (the number S with thermo-ON) to be operated among the N indoor units 31 to 3N based on a plurality of first difference values ΔTa1 to ΔTaN. The plurality of first difference values ΔTa1 to ΔTaN are difference values between the detected temperatures T1 to TN (indoor temperatures) of the N rooms 51 to 5N and the set temperatures Ts1 to TsN corresponding to the detected temperatures. Then, the control device 300 executes the second process (the process in step S8 in FIG. 3) for determining the number of indoor units (the number S with thermo-ON) to be operated from the N indoor units 31 to 3N as the operating indoor units. Then, the control device 300 executes the third process (step S10 in FIG. 3) for operating the operating indoor units determined by the second process.

With this configuration, the number of indoor units to be operated is determined based on the detected temperatures of each of the multiple indoor units and multiple difference values between the detected temperatures and the corresponding set temperatures, and the determined number of indoor units are operated as operating indoor units. Therefore, for example, the coefficient of performance of the refrigeration cycle device can be improved compared to the refrigeration cycle device of the comparative example described above (see the explanations of Figures 5 to 8).

(2) The control device 300 executes the first process (the process for the number of units in S4 in FIG. 3) for each first period (step S2 in FIG. 3). The control device 300 also executes the second process (the process for step S8 in FIG. 3) for each second period (step S6 in FIG. 3). When the refrigeration cycle device 1 is performing cooling operation, the control device 300 calculates multiple (N) first difference values ΔTa1 to ΔTaN by subtracting the set temperatures Ts1 to TsN corresponding to the detected temperatures from the detected temperatures T1 to TN of each of the N indoor units. When the refrigeration cycle device 1 is performing heating operation, the control device 300 calculates multiple (N) first difference values ΔTa1 to ΔTaN by subtracting the detected temperatures T1 to TN corresponding to the set temperatures from the set temperatures Ts1 to TsN of each of the N indoor units. Then, as the number-of-vehicles process, the control device 300 calculates the average value ΔTa of the N first difference values ΔT, as shown in FIG. 4 (see step S26 and formula (1) above).

Then, in step S28, the control device 300 determines whether a second difference value, obtained by subtracting the previously calculated average value from the currently calculated average value, is greater than a first threshold value (a positive value) (ΔTa has increased from the previous time) and whether the currently calculated average value ΔTa is positive. If the first situation is that the answer to step S28 is YES, the control device 300 executes a first number process (step S30) that determines to increase the number of operating vehicles from the current number of operating vehicles (step S22).

In addition, in step S32, the control device 300 determines whether the second difference value is smaller than a negative second threshold value (ΔTa has decreased since the previous time) and the average value ΔTa calculated this time is negative. If the second situation is that the answer to step S32 is YES, the control device 300 executes a second number process (step S34) that determines the number of operating vehicles to be decreased from the current number of operating vehicles (step S22).

With this configuration, when the average value ΔTa is on the rise (the second difference value in step S28 is greater than the first threshold value Th1), the control device 300 determines that the overall deviation between the detected temperature and the set temperature is increasing in the N indoor units, and can increase the number of operating indoor units to reduce this deviation. On the other hand, when the average value ΔTa is on the fall (the second difference value in step S32 is smaller than the second threshold value Th2), the overall deviation between the detected temperature and the set temperature is decreasing in the N indoor units, and can reduce this deviation while decreasing the number of operating indoor units. Therefore, the refrigeration cycle device 1 of this embodiment can optimize the number of thermo-ON units by the first number process and the second number process.

Furthermore, if the average value ΔTa is positive in step S28 (YES in step S28), the control device 300 determines that the number of operating indoor units is too low, and that the average value tends to move away from the desirable value of "0". Therefore, if this is the case, the average value can be brought closer to "0" by increasing the number of operating units in step S30. On the other hand, if the average value ΔTa is negative (YES in step S32), the number of operating units is too high, and that the average value tends to move away from the desirable value of "0". Therefore, by decreasing the number of operating units in step S34, the power consumption can be reduced and the average value can be brought closer to "0".

(3) If the current situation is different from either the first situation or the second situation (if NO is determined in step S32), the control device 300 does not change the number of operating units (does not execute either step S30 or step S34). Therefore, in a situation different from either the first situation or the second situation, the average value ΔTa is assumed to be an appropriate value, and therefore the number of operating units is maintained. Therefore, the refrigeration cycle device 1 can maintain the average value ΔTa, which is an appropriate value.

(4) The first number process in step S30 is a process for determining the number of operating vehicles to be increased by one from the current number of operating vehicles. The second number process in step S34 is a process for determining the number of operating vehicles to be decreased by one from the current number of operating vehicles. Therefore, the control device 300 can perform both the process for increasing and the process for decreasing the number of operating vehicles in a simple manner.

(5) The second process shown in step S8 in FIG. 3 is a process for determining the indoor unit to be operated from among the N indoor units 31 to 3N in order of the indoor unit with the largest first difference value (giving priority to indoor units with large first difference values). Therefore, the refrigeration cycle device 1 can reduce the degree of deviation between the detected temperature and the set temperature by operating an indoor unit with a large degree of deviation.

(6) The second period (one minute as shown in step S6 of FIG. 3) is shorter than the first period (three minutes as shown in step S2 of FIG. 3). As the first period is longer than the second period, frequent increases and decreases in the number of operating units can be suppressed, and the burden on the compressor 10 can be reduced. In addition, the second period is shorter than the first period, so the difference between the detected temperature and the set temperature in the N indoor units can be suppressed.

(7) The control device 300 controls the operating frequency of the motor of the compressor 10 so that the refrigerant pressure (refrigerant evaporation pressure) of the operating indoor units 3s becomes a predetermined value regardless of the number of indoor units with the thermo-ON. With this configuration, the control device 300 can automatically lower the compressor frequency in response to a decrease in the number of indoor units with the thermo-ON. By reducing the amount of refrigerant circulating, the heat transfer area of the outdoor heat exchanger 40 of the heat source unit 2 can be increased relative to the refrigerant circulating flow rate. Therefore, when the number of indoor units with the thermo-ON is small, the coefficient of performance of the refrigeration cycle device 1 can be improved more than when the number of indoor units with the thermo-ON is large.

Embodiment 2.
In the second embodiment, step S4 in Fig. 3 is replaced by step S4A. Fig. 9 is a flowchart of the number processing in step S4A. Comparing Fig. 9 with Fig. 4, steps S28 and S32 in Fig. 4 are replaced by steps S28A and S32A, respectively, in the flowchart in Fig. 9.

In the example of FIG. 9, the control device 300 does not execute the process of determining whether ΔTa>0 in step S28A, and does not execute the process of determining whether ΔTa<0 in step S32A. In other words, in the example of FIG. 9, the control device 300 may determine whether the second difference value is greater than the first threshold value Th1 in step S28A, and determine whether the second difference value is less than the second threshold value Th2 in step S32A.

In this configuration, if the second difference value is greater than the second threshold value Th2 and less than the first threshold value Th1, the number of operating units is not changed (the processes of steps S30 and S34 are not executed). Therefore, in the refrigeration cycle device 1 of embodiment 2, if the average value ΔTa is neither increasing nor decreasing, the number of operating units is assumed to be appropriate, and the number of indoor units can be maintained.

Modifications of the first and second embodiments will be described below.
(1) The refrigeration cycle apparatus 1 of the above embodiment uses the average value ΔTa of the first difference values ΔTa1 to ΔTaN. However, the refrigeration cycle apparatus 1 may use another value based on the first difference values ΔTa1 to ΔTaN instead of the average value ΔTa. The other value may be, for example, a total value of the first difference values ΔTa1 to ΔTaN. Furthermore, the other value may be a multiplication value of the first difference values ΔTa1 to ΔTaN.

(2) The first threshold value Th1 in step S28 of FIG. 4 may be a positive value that is very close to "0". In this case, the process of determining whether the second difference value is greater than the first threshold value Th1 is replaced by a process of determining whether the currently calculated ΔTa is greater than the previously calculated ΔTa. Also, the second threshold value Th2 in step S32 of FIG. 4 may be a negative value that is very close to "0". In this case, the process of determining whether the second difference value is smaller than the second threshold value Th2 is replaced by a process of determining whether the currently calculated ΔTa is smaller than the previously calculated ΔTa.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and is intended to include all modifications within the meaning and scope of the claims.

1 refrigeration cycle device, 2 heat source unit, 3 indoor unit, 3s operating indoor unit, 4 temperature sensor, 10 compressor, 10a refrigerant inlet, 10b refrigerant outlet, 11 electronic expansion valve, 20 indoor heat exchanger, 21 indoor fan, 40 outdoor heat exchanger, 61 outdoor fan, 100 four-way valve, 300 control device, 302 memory, 303 communication interface, 312 receiving unit, 314 processing unit, 316 storage unit, 318 transmitting unit.

Claims (10)

A heat source machine having a compressor that discharges a refrigerant;
A plurality of indoor units;
A control device having a memory that stores the set temperatures of each of the indoor units;
a plurality of temperature sensors that detect the temperature of each room in which the plurality of indoor units are installed as a detected temperature;
The control device includes:
execute a first process of determining the number of indoor units to be operated among the plurality of indoor units based on a plurality of first difference values between the detected temperatures of the plurality of indoor units and the set temperatures corresponding to the detected temperatures;
execute a second process of determining the number of indoor units in operation from the plurality of indoor units as operating indoor units;
A refrigeration cycle apparatus that executes a third process of operating the operating indoor unit. The control device includes:
execute the first process for each first period;
execute the second process every second period;
The plurality of first difference values are
When the refrigeration cycle device is performing a cooling operation, the temperature is calculated by subtracting a set temperature corresponding to the detected temperature from the detected temperature of each of the plurality of indoor units,
When the refrigeration cycle device is performing a heating operation, the temperature setting of each of the indoor units is calculated by subtracting the detected temperature corresponding to the set temperature from the set temperature of each of the indoor units,
The control device, as the first process,
Calculating an average value of the plurality of first difference values;
execute a first number-of-vehicles process to determine an increase in the number of operating vehicles from the current number of operating vehicles when a second difference value obtained by subtracting the previously calculated average value from the currently calculated average value is greater than a first threshold value that is positive;
The refrigeration cycle apparatus according to claim 1 , further comprising: a second number-of-units process for determining the number of operating units to be decreased from the current number of operating units when the second difference value is smaller than a negative second threshold value. The refrigeration cycle device according to claim 2, wherein the control device does not change the number of operating units when the second difference value is greater than the second threshold value and less than the first threshold value. The control device includes:
When the second difference value is greater than the first threshold value and the currently calculated average value is a positive value, the first number process is executed.
The refrigeration cycle apparatus according to claim 2 , wherein the second number process is executed in a second situation in which the second difference value is smaller than the second threshold value and the currently calculated average value is negative. The refrigeration cycle device according to claim 4, wherein the control device does not change the number of operating units when a situation is different from either the first situation or the second situation. The first number process is a process of determining the number of operating vehicles to be increased by one from the current number of operating vehicles,
The refrigeration cycle apparatus according to any one of claims 2 to 5, wherein the second number process is a process of determining the number of operating units to be reduced by one from the current number of operating units. The refrigeration cycle device according to any one of claims 2 to 6, wherein the second process is a process of determining, among the plurality of indoor units, an indoor unit having a larger first difference value as the operating indoor unit. The refrigeration cycle device according to any one of claims 2 to 7, wherein the second period is shorter than the first period. The refrigeration cycle device according to any one of claims 1 to 8, wherein the control device executes, as the third process, a process of controlling the operating frequency of the compressor so that the pressure of the refrigerant in the operating indoor unit becomes a predetermined value regardless of the number of operating units. A method for controlling a refrigeration cycle device, comprising:
A heat source machine having a compressor that discharges a refrigerant;
A plurality of indoor units;
a control device having a memory that stores the set temperatures of the indoor units,
Each of the indoor units has a temperature sensor that detects the temperature of a room in which the indoor unit is installed as a detected temperature,
The control method includes:
determining a number of indoor units to be operated among the plurality of indoor units based on a plurality of first difference values between the detected temperatures of the plurality of indoor units and the set temperatures corresponding to the detected temperatures;
determining the number of indoor units in operation from the plurality of indoor units as operating indoor units;
and operating the operating indoor unit.

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