JP6707189B2 - Air conditioner and fan speed control method for air conditioner - Google Patents

Description

The present invention relates to an air conditioner and a fan speed control method for an air conditioner, and more particularly to a multi-type air conditioner having a plurality of refrigeration cycle circuits and a fan speed control method for the air conditioner. Is.

Conventionally, there is a multi-type air conditioner in which a plurality of indoor units are connected to one outdoor unit and the plurality of indoor units can be individually operated and controlled. In a multi-type air conditioner, when the number of connectable indoor units increases and the capacity band required for outdoor units increases, the maximum capacity is the capacity when the number of connected indoor units becomes maximum. You must secure the outdoor unit. Therefore, it becomes necessary to mount a large compressor on the outdoor unit. When a large compressor is installed in the outdoor unit, if only one indoor unit is operating and the air conditioning load of the room in which the indoor unit is installed is small, operate at the lowest frequency allowed by the compressor. Becomes However, in the case of a large compressor, the operating capacity of the compressor may increase with respect to the air conditioning load. As a result, there is a concern that the compressor may be operated intermittently and comfort may be impaired.

As means for solving such a problem, Patent Literature 1 discloses an outdoor heat exchanger in which two compressors, two four-way valves, and two throttles are mounted in one outdoor unit. Is divided into two systems to describe a multi-type air conditioner having two systems of refrigerant circuits. In a multi-type air conditioner having two independent refrigeration cycles described in Patent Document 1, in an outdoor heat exchanger having a plurality of paths through which refrigerant of the refrigeration cycle flows, different refrigeration cycle paths have strip-shaped fins. Are arranged alternately in the length direction. Further, the air conditioner described in Patent Document 2 is a multi-type air conditioner for both heating and cooling that has a plurality of outdoor heat exchangers, and each outdoor heat exchanger has a plurality of band-shaped laminated fins. Moreover, the fin is divided into a first heat exchange pipe portion and a second heat exchange pipe portion in the longitudinal direction of the fin.

JP, 2006-153333, A JP, 2000-39223, A

When the configuration in which the outdoor heat exchanger is divided into two systems is adopted like the air conditioners of Patent Document 1 and Patent Document 2, the capacity to be exhibited per system is half, so the maximum capacity of the compressor It is possible to reduce the minimum capacity of the compressor during the individual operation of the indoor unit while ensuring the above. However, in the air conditioners shown in Patent Documents 1 and 2, no consideration is given to the fan speed control of the fan that supplies air to the outdoor heat exchanger when operating the two systems at the same time. Therefore, it becomes difficult to simultaneously control the refrigeration cycles of the systems having different air conditioning loads.

In the two-system refrigeration cycle circuit, an appropriate stable state of the refrigerant exists for each system. For example, in the cooling operation, the required degree of subcooling in the outdoor heat exchanger in each system varies depending on the air conditioning load. Therefore, in order to maintain an appropriate degree of subcooling in each system in the outdoor heat exchanger, each system must be provided with a fan for the outdoor heat exchanger and a fan motor. That is, in a multi-type air conditioner having two refrigeration cycles as in Patent Document 1 and Patent Document 2, two fans and two fan motors are required as a whole. Therefore, there is a problem that control becomes complicated.

The present invention has been made in order to solve the above problems, and is an air conditioner having a plurality of refrigeration cycles, and balances the refrigeration cycles of the respective systems by simple control to perform air conditioning. An object of the present invention is to provide an air conditioner and a fan speed control method for the air conditioner that enable stable operation of the entire machine.

An air conditioner according to the present invention includes an outdoor unit and a plurality of indoor units, the outdoor unit, a plurality of compressors, a plurality of outdoor heat exchangers, a plurality of flow path switching device, a plurality of expansion. a valve, and a single outdoor fan for sending air to the plurality of outdoor heat exchanger, a single outdoor fan motor for driving the single outdoor fan, an outdoor unit control unit for controlling the outdoor unit Having the plurality of indoor units, each has an indoor heat exchanger, the compressor, the outdoor heat exchanger, the flow path switching device, the expansion valve and a part of the plurality of indoor units The indoor heat exchanger of the indoor unit is an air conditioner in which a plurality of refrigeration cycle circuits connected by refrigerant piping are configured, the outdoor unit control means, the refrigeration cycle circuit of the plurality of systems simultaneously When operating, obtain the target condensing temperature of the refrigerant in each of the outdoor heat exchangers of the refrigeration cycle circuit of the plurality of systems, for each of the refrigeration cycle circuits of the plurality of systems, the operating frequency of the compressor. Acquired, for each of the plurality of refrigeration cycle circuits, a plurality of frequency bands that are defined in stages corresponding to the height of the operating frequency band of the compressor, and are defined for each of the plurality of frequency bands. From the target condensing temperature of the outdoor heat exchanger, the target condensing temperature based on the acquired operating frequency of the compressor is specified, and the refrigeration cycle circuit having the compressor with the largest operating frequency. And a difference between the frequency band and the frequency band of the refrigeration cycle circuit having the compressor having the smallest operating frequency is calculated, and the plurality of the plurality of stages are defined in stages corresponding to the difference in the frequency band. From the correction value of the target condensing temperature, the correction value is determined based on the calculated difference of the frequency band, and the target condensing temperature of the refrigeration cycle circuit having the compressor with the largest operating frequency is set to the target condensing temperature. The rotation speed of the single outdoor fan motor is controlled so that the condensation temperature of the outdoor heat exchanger is corrected by the correction value to reach the target condensation temperature corrected by the correction value .

Further, a fan speed control method for an air conditioner according to the present invention includes an outdoor unit and a plurality of indoor units, the outdoor unit is a plurality of compressors, a plurality of outdoor heat exchangers, a plurality of flow paths. It has a switching device, a plurality of expansion valves, a single outdoor fan for sending air to the plurality of outdoor heat exchanger, a single outdoor fan motor for driving the single outdoor fan, the compressor And a plurality of refrigeration cycle circuits in which the outdoor heat exchanger, the flow path switching device, the expansion valve, and the indoor heat exchanger of some indoor units of the plurality of indoor units are connected by refrigerant piping In the air conditioner, when the plurality of refrigeration cycle circuits are simultaneously operated, a setting step of setting a target condensing temperature of the refrigerant of the air conditioner, and the single outdoor fan based on the target condensing temperature look including a motor control step of controlling the rotation of the motor, the setting step, for each of the refrigeration cycle circuit of the plurality of systems, acquires the operation frequency of the compressor, high and low band operation frequency of said compressor A plurality of frequency bands that are defined in a stepwise manner corresponding to, and among the target condensing temperatures of the outdoor heat exchanger that are defined for each of the plurality of frequency bands, the refrigeration cycle circuits of the plurality of systems. For each, the target condensing temperature based on the acquired operating frequency of the compressor, a specific step of specifying, the operating frequency is the frequency band of the refrigeration cycle circuit having the compressor having the largest operating frequency, A band difference calculation step of calculating a difference with the frequency band of the refrigeration cycle circuit having the smallest compressor, and a plurality of the target condensing temperatures defined stepwise corresponding to the difference of the frequency band. A correction value determination step of determining the correction value based on the difference of the frequency bands calculated in the band difference calculation step from the correction values, and the refrigeration cycle having the compressor with the largest operating frequency. and a correction step of correcting the target condensing temperature of the circuit with the correction value are Nde free.

According to the air conditioner and the fan speed control method for an air conditioner according to the present invention, even when the air conditioning loads of the refrigeration cycle circuits of the multiple systems are different, the degree of supercooling is excessive in each system. Or, a state in which the degree of supercooling is insufficient will not be caused. As a result, in each system, an operation with excessive capacity or an operation with a shortage of capacity is prevented, and a balanced cooling operation can be executed in the entire air conditioner.

It is a lineblock diagram of an air conditioner in an embodiment of the invention. It is a graph which shows the present condensation temperature, a target condensation temperature, and the relationship with the stable rotation speed of an outdoor fan motor. It is a figure which shows the difference between the present condensation temperature and target condensation temperature, and the stable rotation speed of an outdoor fan motor. 5 is a flowchart showing a processing procedure of fan speed control according to the embodiment of the present invention. It is a flow chart which shows the procedure of the start processing of cooling operation. It is a flowchart which shows the procedure of the process which extracts the system of the indoor unit which is operating. It is a flowchart which shows the procedure of the determination process of target condensing temperature. It is a flow chart which shows the procedure of processing which calculates a band difference. It is a flowchart which shows the procedure of the process which sets a target condensing temperature. It is a flow chart which shows the processing procedure of rotation number determination of an outdoor fan motor. It is a graph of the rotation speed step which shows control of the rotation speed of an outdoor fan motor. It is a flow chart which shows the processing procedure of rotation speed change of an outdoor fan motor.

Embodiments of an air conditioner according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Further, in the following drawings, the size of each component may be different from the actual device.

Embodiment.
FIG. 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention. The air conditioner of the present embodiment includes an outdoor unit X as a heat source unit, and an indoor unit Y1, an indoor unit Y2, an indoor unit Y3, and an indoor unit Y4, which are utilization units connected in parallel to the outdoor unit X. I have it.

The outdoor unit X includes a compressor 1A and a compressor 1B, a four-way valve 2A and a four-way valve 2B, an outdoor heat exchanger 3A and an outdoor heat exchanger 3B, an outdoor fan 4, an outdoor fan motor 5, and an expansion valve 6A1. , Expansion valve 6A2, expansion valve 6B1, and expansion valve 6B2, liquid side valve 10A and liquid side valve 10B, gas side valve 11A and gas side valve 11B. The outdoor unit X includes a temperature detecting unit 12A and a temperature detecting unit 12B, a temperature detecting unit 13A and a temperature detecting unit 13B, a temperature detecting unit 14, a temperature detecting unit 15A and a temperature detecting unit 15B, and an outdoor unit controlling unit. And 19.

The outdoor unit control means 19 is a controller that controls the outdoor unit X as a whole. The compressors 1A and 1B are, for example, frequency changeable compressors. The expansion valves 6A1 and 6A2 and the expansion valves 6B1 and 6B2 have a structure capable of variably controlling the opening degree. The four-way valve 2A and the four-way valve 2B switch the flow direction of the gas refrigerant discharged from the compressor 1A and the compressor 1B. The outdoor heat exchanger 3A and the outdoor heat exchanger 3B are heat exchangers that exchange heat between the outside air and the refrigerant. The outdoor fan 4 is a blower that blows outside air to the outdoor heat exchanger 3A and the outdoor heat exchanger 3B. The outdoor fan 4 is rotationally driven by the outdoor fan motor 5. The expansion valve 6A1, the expansion valve 6A2, the expansion valve 6B1, and the expansion valve 6B2 are valves that decompress the refrigerant. The discharge temperature of the compressor 1A is detected by the temperature detecting means 12A, and the discharge temperature of the compressor 1B is detected by the temperature detecting means 12B. The refrigerant saturation temperature of the outdoor heat exchanger 3A is detected by the temperature detecting means 13A, and the refrigerant saturation temperature of the outdoor heat exchanger 3B is detected by the temperature detecting means 13B. The temperature of the outside air is detected by the temperature detecting means 14. The temperature of the outdoor heat exchanger 3A is detected by the temperature detecting means 15A, and the temperature of the outdoor heat exchanger 3B is detected by the temperature detecting means 15B. In the following description, the alphabets after the reference numerals of the constituent elements of the outdoor unit X may be omitted, but in that case, the constituent elements are collectively referred to.

The indoor units Y1, Y2, Y3, and Y4 are supplied with cooling heat or warm heat from the outdoor unit X and supply cooling air or heating air to the air conditioning target area. In the following description, the numbers after the indoor unit Y may be omitted, but in that case, the indoor units Y1, Y2, Y3, and Y4 are collectively referred to. In addition, Y1 is added after the code of each device of the indoor unit Y1, Y2 is added after the code of each device of the indoor unit Y2, Y3 is added after the code of each device of the indoor unit Y3, and indoor unit Y4 In the drawing, Y4 is added after the reference numeral of each device. In the description of each of these devices, the numbers after the Y code may be omitted, but the devices of the indoor units Y1, Y2, Y3, and Y4 are collectively referred to.

The indoor unit Y has an indoor heat exchanger 7Y, an indoor fan 8Y, an indoor fan motor 9Y, a temperature detecting means 16Y, a temperature detecting means 17Y, and an indoor unit controlling means 18Y. The indoor unit control means 18Y is a controller that controls the indoor unit Y as a whole. The refrigerant saturation temperature of the indoor heat exchanger 7Y is detected by the temperature detecting means 16Y. The air temperature in the room where the indoor unit Y is installed is detected by the temperature detecting means 17Y.

In the present embodiment, the air conditioner has a first system A and a second system B as refrigeration cycles. The first system A of the refrigeration cycle includes a compressor 1A, a four-way valve 2A, an outdoor heat exchanger 3A, an expansion valve 6A1, an expansion valve 6A2, a liquid side valve 10A, a gas side valve 11A, an indoor heat exchanger 7Y1, and an indoor heat exchanger. It is composed of the exchanger 7Y2. The indoor heat exchanger 7Y1 and the indoor heat exchanger 7Y2 are connected in parallel by piping. The second system B of the refrigeration cycle includes a compressor 1B, a four-way valve 2B, an outdoor heat exchanger 3B, an expansion valve 6B1, an expansion valve 6B2, a liquid side valve 10B, a gas side valve 11B, an indoor heat exchanger 7Y3, and an indoor heat exchanger. It is composed of the exchanger 7Y4. The indoor heat exchanger 7Y3 and the indoor heat exchanger 7Y4 are connected in parallel by piping.

Next, an operation when the cooling operation is performed by the air conditioner according to the present embodiment will be described. The low-temperature low-pressure gas refrigerant is compressed by the compressor 1 and is discharged as a high-temperature high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 1 goes to the four-way valve 2. The flow path of the four-way valve 2 during the cooling operation is set in the direction shown by the solid line in FIG. The high-temperature and high-pressure gas refrigerant passes through the four-way valve 2 and flows into the outdoor heat exchanger 3. At this time, the gas refrigerant is condensed and liquefied while radiating heat to the outdoor air blown from the outdoor fan 4, and becomes a high-pressure liquid refrigerant. After that, the high-pressure liquid refrigerant is decompressed by the expansion valve 6, becomes a low-pressure two-phase state, and flows into the indoor heat exchanger 7Y. In the indoor heat exchanger 7Y, the low-pressure two-phase refrigerant absorbs heat from the indoor air blown to the indoor heat exchanger 7Y by the indoor fan 8Y and becomes a low-pressure gas refrigerant. Then, the low-pressure gas refrigerant returns to the compressor 1 via the four-way valve 2. By such a cooling operation, the temperature of the air in the room where the indoor unit Y is installed can be lowered.

An example of the operation when one refrigeration cycle is operating in the above-described cooling operation will be described. The user issues a request for cooling operation to the indoor unit Y1 of the first system A by operating the remote control. The indoor temperature of the room in which the indoor unit Y1 is attached is detected by the temperature detecting means 17Y1. Then, the indoor unit control means 18Y1 calculates the difference between the indoor temperature detected by the temperature detection means 17Y1 and the set temperature set by the user, and transmits the difference to the outdoor unit control means 19 of the outdoor unit X. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1A based on the transmitted difference, and drives the compressor 1A. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y1 is 27° C., the set temperature set by the user is 23° C., and the operating frequency of the compressor 1A is 60 Hz.

At this time, the outdoor unit control means 19 controls the rotation speed of the outdoor fan motor 5 so that the refrigerant saturation temperature of the outdoor heat exchanger 3A detected by the temperature detection means 13A, that is, the condensation temperature, reaches a target value. .. In this specification, the condensing temperature required for the outdoor heat exchanger 3 is set as the target condensing temperature corresponding to the operating frequency of the compressor 1. For example, when the operating frequency of the compressor 1A is 60 Hz, the target condensation temperature is 38°C. Table 1 shows the relationship between the operating frequency bandwidth of the compressor and the target condensing temperature.

Next, a phenomenon when the refrigeration cycle of the first system A and the refrigeration cycle of the second system B are simultaneously operating will be described. When the user issues a request for the cooling operation to the indoor unit Y1 of the first system A by the remote control operation, the following control is performed. The indoor temperature of the room in which the indoor unit Y1 is attached is detected by the temperature detecting means 17Y1. Then, the indoor unit control means 18Y1 calculates the difference between the indoor temperature detected by the temperature detection means 17Y1 and the set temperature set by the user, and transmits the difference to the outdoor unit control means 19 of the outdoor unit X. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1A based on the transmitted difference, and drives the compressor 1A. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y1 is 30° C., the set temperature set by the user is 16° C., and the operating frequency of the compressor 1A is 80 Hz.

When the user issues a request for cooling operation to the indoor unit Y3 of the second system B by operating the remote control, the following control is performed. The indoor unit control means 18Y3 of the indoor unit Y3 detects the indoor temperature of the room to which the indoor unit Y3 is attached via the temperature detection means 17Y3. Then, the indoor unit control means 18Y3 calculates the difference between the indoor temperature detected by the temperature detection means 17Y3 and the set temperature set by the user, and transmits the difference to the outdoor unit control means 19 of the outdoor unit X. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1B based on the transmitted difference, and operates the compressor 1B. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y3 is 26° C., the set temperature set by the user is 24° C., and the operating frequency of the compressor 1B is 30 Hz.

In this way, when the air conditioning load of the room is greatly different between the first system A and the second system B, the frequencies of the compressor 1A and the compressor 1B are significantly different, and the respective targets in the first system A and the second system B are set. The condensation temperature will be different. For example, when the operating frequency of the compressor 1A is 80 Hz, the target condensing temperature is 39°C, and when the operating frequency of the compressor 1B is 30 Hz, the target condensing temperature is 36°C.

In such an operating state, the required supercooling degree in the first system A is, for example, 10°C, and the required subcooling degree in the second system B is, for example, 3°C. Since the outdoor unit is the single outdoor unit X, the outdoor air temperature is the same. Therefore, when the rotation speed of the outdoor fan motor 5 is set to match the rotation speed of the first system A, the second system B side is over-cooled too much and the capacity is likely to be excessive. On the contrary, when the rotation speed of the outdoor fan 4 is adjusted to match the rotation speed of the second system B, the degree of subcooling is insufficient on the side of the first system A, and the operation tends to be insufficient.

Therefore, in the present embodiment, the target condensing temperature when operating the first system A and the second system B simultaneously is based on the target condensing temperature of the system in which the operating frequency of the compressor is the highest from the viewpoint of high pressure protection. And The difference between the reference target condensing temperature and the target condensing temperature of the system with the lowest operating frequency of the compressor is calculated, and the correction value of the reference target condensing temperature is determined based on the difference. Then, the target condensing temperature of the system with the highest operating frequency of the compressor is corrected with the correction value. Further, the rotation speed of the outdoor fan 4 is controlled so that the condensation temperature of the compressor of each system becomes the corrected target condensation temperature. As a result, the refrigeration cycle of each system can be balanced, and stable operation can be performed in the entire system.

An example of specific control will be described. The operation when operating one system is as follows. The user issues a request for cooling operation to the indoor unit Y1 of the first system A by operating the remote control. As described above, the indoor unit control means 18Y1 of the indoor unit Y1 sends the difference between the indoor temperature of the room in which the indoor unit Y1 is installed and the set temperature set by the user to the outdoor unit control means 19 of the outdoor unit X. Send. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1A based on the transmitted difference, and drives the compressor 1A. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y1 is 27° C., the set temperature is 23° C., and the operating frequency of the compressor 1A is 60 Hz. The target condensation temperature at this time is, for example, 38° C., which corresponds to frequency band 4 of the target condensation temperature in Table 1 above. The outdoor unit control means 19 adjusts the rotation speed of the outdoor fan motor 5 so that the condensation temperature of the refrigerant detected by the temperature detection means 13A becomes 38°C.

Next, an example of operating two series simultaneously will be shown. The user issues a request for cooling operation to the indoor unit Y1 of the first system A by operating the remote control. As described above, the indoor unit control means 18Y1 of the indoor unit Y1 sends the difference between the indoor temperature of the room in which the indoor unit Y1 is installed and the set temperature set by the user to the outdoor unit control means 19 of the outdoor unit X. Send. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1A based on the transmitted difference, and drives the compressor 1A. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y1 is 30° C., the set temperature is 16° C., and the operating frequency of the compressor 1A is 80 Hz. The target condensation temperature at this time is, for example, 38° C., which corresponds to frequency band 4 of the target condensation temperature in Table 1 above.

Further, the user operates the remote controller to issue a request for cooling operation to the indoor unit Y3 of the second system B. As described above, the indoor unit control means 18Y3 of the indoor unit Y3 sends the difference between the indoor temperature of the room in which the indoor unit Y3 is installed and the set temperature set by the user to the outdoor unit control means 19 of the outdoor unit X. Send. The outdoor unit control means 19 of the outdoor unit X determines the operating frequency of the compressor 1B based on the transmitted difference, and operates the compressor 1B. For example, it is assumed that the indoor temperature detected by the temperature detecting means 17Y3 is 26° C., the set temperature is 24° C., and the operating frequency of the compressor 1B is 30 Hz. The target condensing temperature at this time is, for example, 36° C., which corresponds to frequency band 2 of the target condensing temperature in Table 1 above.

In such a case, the outdoor unit control means 19 of the outdoor unit X belongs to the frequency band 4 with the target condensing temperature of the first system A being 38° C., and the target condensing temperature of the second system B is 36° C. with the frequency band 2. Recognize that it belongs. Here, the target condensation temperature of the first system A is 38° C. and the operating frequency of the compressor 1A is 80 Hz, whereas the target condensation temperature of the second system B is 36° C. and the operating frequency of the compressor 1B. Is 30 Hz, and the operating frequency of the compressor 1A is higher than that of the compressor 1B. Therefore, the outdoor unit control means 19 uses the target condensation temperature of the first system A, that is, 38° C. as a reference. The outdoor unit control means 19 calculates the frequency band difference between the first system A and the second system B, and determines the correction value according to the difference. Table 2 is a table showing the relationship between the frequency band difference and the correction value of the target condensation temperature in the present embodiment.

In the above example, the frequency band difference is 4-2=2, and the correction value for the target condensation temperature is +1.0°C. Therefore, the outdoor unit control means 19 corrects the target condensation temperature of the first system A, which is the reference value, from 38° C. to 38° C.+1.0° C.=39° C.

After the operation of the compressor 1 is started, the temperature detection means 13 detects the refrigerant saturation temperature of the outdoor heat exchanger 3 which is a condenser, that is, the condensation temperature. The rotation speed of the outdoor fan 4 is set so that the condensation temperature of the outdoor heat exchanger 3 detected by the temperature detection means 13 reaches the target condensation temperature corrected as described above. That is, after the operation of the compressor 1 is started, the condensing temperature of the refrigerant of the outdoor heat exchanger 3A is corrected by the temperature detecting means 13A, and the condensing temperature of the refrigerant of the outdoor heat exchanger 3B detected by the temperature detecting means 13B is corrected. The outdoor unit control means 19 sets the number of rotations of the outdoor fan 4 so that the target condensing temperature becomes 39°C. Then, the rotation speed of the outdoor fan motor 5 is adjusted based on the set rotation speed of the outdoor fan 4.

Assuming that the current condensing temperature is Tc and the target condensing temperature is Tcm, the larger Tc is, the larger the difference between the condensing temperature Tc and the target condensing temperature Tcm is, and the larger the air volume required for heat exchange is. The required rotation speed of the outdoor fan 4, in other words, the stable rotation speed, increases. FIG. 2 is a graph showing the relationship between the current condensing temperature, the target condensing temperature, and the stable rotation speed of the outdoor fan motor. The horizontal axis represents the present condensing temperature Tc, and the vertical axis represents the stable rotation speed N of the outdoor fan motor 5. In FIG. 2, a line L21 indicates a case where the target condensation temperature Tcm is 36° C., a line L22 indicates a case where the target condensation temperature Tcm is 38° C., and a line L23 indicates a case where the target condensation temperature Tcm is 40° C. The relationship with the number N is shown.

In the present embodiment, in order to further stabilize the state of the refrigeration cycle, control of the rotation speed of the outdoor fan 4, that is, control of the rotation speed of the outdoor fan motor 5 is executed stepwise. The outdoor unit controller 19 receives the condensation temperature of the outdoor heat exchanger 3 detected by the temperature detector 13, and the control interval for determining the rotation speed of the outdoor fan motor 5 is, for example, 60 seconds. Since the amount of air passing through the outdoor heat exchanger 3 changes according to the set rotation speed of the outdoor fan 4, the current condensation temperature changes. In the present embodiment, in order to make it difficult for hunting to occur with respect to the current change in the condensation temperature, the change in the rotation speed of the outdoor fan motor 5 has a hysteresis. FIG. 3 is a diagram showing the relationship between the difference between the current condensation temperature and the target condensation temperature and the stable rotation speed of the outdoor fan motor. In FIG. 3, the horizontal axis represents ΔTc, which is the difference between the condensation temperature Tc and the target condensation temperature Tcm, and the vertical axis represents the stable rotation speed N of the outdoor fan motor 5. As shown by the solid line in FIG. 3, the stable rotation speed N of the outdoor fan motor 5 is controlled to change stepwise in accordance with the change in the difference ΔTc. Further, as shown by a dotted arrow in FIG. 3, there is hysteresis in the change in the stable rotation speed N of the outdoor fan motor 5.

FIG. 4 is a flowchart showing a processing procedure of fan speed control according to the embodiment of the present invention. In step S1, a cooling operation start process is executed. FIG. 5 is a flowchart showing the procedure of the start processing of the cooling operation. When the user issues a request for the cooling operation to the indoor unit Y by operating the remote control, the indoor unit control means 18Y receives the operation start command in step S1-1. Upon receiving the operation start command, the indoor unit control means 18Y starts the operation of the indoor fan motor 9Y in step S1-2. Next, in step S1-3, the outdoor unit control means 19 receives an operation start command from the indoor unit control means 18Y. Then, the process proceeds to step S2 in FIG.

In step S2, a process of extracting the system of the indoor unit that is operating is executed. FIG. 6 is a flowchart showing a procedure of processing for extracting a system of an indoor unit that is operating. In step S2-1, the outdoor unit control means 19 identifies the system of the refrigeration cycle circuit that is operating based on the received operation start command. If the operation start command is received from the indoor unit control means 18Y1 or the indoor control means 18Y2, the outdoor unit control means 19 specifies that the first system A is operating. If the operation start command is received from the indoor unit control means 18Y3 or the indoor control means 18Y4, the outdoor unit control means 19 identifies that the second system B is operating. Next, in step S2-2, the outdoor unit control means 19 executes an adjustment process at the start of operation. In the present embodiment, the adjustment processing at the start of operation includes adjustment of the operation start frequency of the compressor 1, adjustment of the rotation speed of the outdoor fan motor 5, adjustment of the flow path of the four-way valve 2, opening of the expansion valve 6. Adjustment. Then, the process proceeds to step S3 in FIG.

In step S3, it is checked whether the refrigeration cycle in operation is one system. When the refrigerating cycle in operation is one system, a process progresses to step S4. When the refrigerating cycle in operation is multiple systems, a process progresses to step S6.

In step S4, the outdoor unit control means 19 detects the current operating frequency of the compressor 1 and determines the target condensing temperature from the correspondence table in Table 1 above based on the detected operating frequency. Identify the frequency band of. Next, in step S5, the target condensing temperature is determined. FIG. 7 is a flowchart showing the procedure of the target condensation temperature determination process. In step S5-1, the outdoor unit control means 19 extracts the current condensation temperature Tc based on the refrigerant saturation temperature of the outdoor heat exchanger 3 detected by the temperature detection means 13. Next, in step S5-2, the outdoor unit control means 19 determines the target condensing temperature Tcm set in the frequency band specified in step S4. Then, the process proceeds to step S10 in FIG.

On the other hand, in step S6, the current operating frequency of the compressor 1 is detected for each system of the operating refrigeration cycle, and based on the detected operating frequency, the target is selected from the correspondence table in Table 1 above. Identify the frequency band for determining the condensation temperature Tcm. The case of proceeding to step S6 is the case where the first system A and the second system B are in operation in the present embodiment. Therefore, in step S6, the outdoor unit control means 19 specifies the frequency band of the correspondence table of Table 1 based on the operating frequency of the compressor 1A for the first system A, and the compressor 1B for the second system B. The frequency band in the correspondence table of Table 1 is specified based on the operating frequency of. Then, the process proceeds to step S7. In step S7, the outdoor unit control means 19 performs a band difference calculation process. FIG. 8 is a flowchart showing a procedure of processing for calculating the band difference. In step S7-1, the outdoor unit control means 19 extracts the frequency band having the largest value among the frequency bands specified in step S6 and sets it as the reference band. Next, in step 7-2, the frequency band having the smallest value is extracted from the frequency bands specified in step S6. Then, the difference between the reference band determined in step S7-1 and the frequency band having the smallest value, that is, the frequency band difference is calculated. Further, a refrigeration cycle system in which the operating frequency of the compressor 1 belongs to the reference band is used as a reference system. Then, the process proceeds to step S8 in FIG.

In step S8, the outdoor unit control means 19 determines the correction value Tcmh of the target condensation temperature corresponding to the frequency band difference calculated in step S7-2, based on the above-mentioned Table 2. Next, the process proceeds to step S9, and the outdoor unit control means 19 sets the target condensing temperature. FIG. 9 is a flowchart showing a procedure of processing for setting the target condensation temperature. In step S9-1, the outdoor unit control means 19 determines the current condensation temperature Tc based on the refrigerant saturation temperature of the outdoor heat exchanger 3 detected by the temperature detection means 13 for each operating refrigeration cycle system. To extract. The case of proceeding to step S9-1 is the case where the first system A and the second system B are in operation as described above. Therefore, in step S9-1, for the first system A, the outdoor unit control means 19 extracts the current condensation temperature Tca of the outdoor heat exchanger 3A based on the refrigerant saturation temperature detected by the temperature detection means 13A. Then, for the second system B, the current condensation temperature Tcb of the outdoor heat exchanger 3B is extracted based on the refrigerant saturation temperature detected by the temperature detection means 13B. Further, the band of the operating frequency of the compressor 1 sets the condensation temperature of the refrigeration cycle system set in the reference system in step S7-1 as the condensation temperature Tc of the system, and uses it in the subsequent processing. That is, the condensation temperature Tc of the system is the condensation temperature Tca or Tcb.

Next, in step S9-2, the outdoor unit control means 19 sets the target condensation temperature base Tcm_base of the system. In step S7-1, the target condensing temperature of the system of the refrigeration cycle that is specified that the operating frequency of the compressor 1 belongs to the reference band is set as the target condensing temperature base Tcm_base of the system. That is, the target condensing temperature of the refrigeration cycle system belonging to the band in which the operating frequency of the compressor 1 is the largest is set as the target condensing temperature base Tcm_base of the system. The system target condensation temperature base Tcm_base is used for subsequent control.

Next, in step S9-3, the outdoor unit control means 19 corrects the target condensation temperature base Tcm_base of the system by the correction value Tcmh determined in step S8, and sets the target condensation temperature Tcm. Specifically, the correction value Tcmh is added to the target condensation temperature base Tcm_base. Then, the process proceeds to step S10 in FIG.

In step S10, the outdoor unit control means 19 calculates the difference ΔTc between the current system condensing temperature Tc and the target condensing temperature Tcm. When the refrigeration cycle in operation is one system, the target condensation temperature Tcm calculated in step S5 is used to calculate the difference ΔTc, and when the refrigeration cycle in operation is two systems, the difference ΔTc is calculated in step S9. The target condensation temperature Tcm set in -3 is used. When the refrigerating cycle in operation is two systems, the condensing temperature Tc is the condensing temperature obtained by the temperature detecting means 13 in the refrigerating cycle system set as the reference system in step S7-1.

Next, in step S11, the rotation speed of the outdoor fan motor 5 is determined. FIG. 10 is a flowchart showing a processing procedure for determining the rotation speed of the outdoor fan motor. In step S11-1, the outdoor unit control means 19 determines the condensation temperature difference band based on the difference ΔTc calculated in step S10. The condensing temperature difference band is defined stepwise corresponding to the band of the difference ΔTc between the condensing temperature Tc and the target condensing temperature Tcm. Table 3 is a table showing thresholds of the temperature difference width used for setting the condensation temperature difference band in the present embodiment. Further, Table 4 is a table in which the difference band between the condensation temperature Tc and the target condensation temperature Tcm and the condensation temperature difference band are associated with each other.

When the threshold values in Table 3 are applied to the condensation temperature difference band 1 in Table 4, the condensation temperature difference band 1 corresponds to the band Tc≦Tcm−5. That is, the condensation temperature difference band 1 corresponds to the temperature difference band when the current condensation temperature Tc is significantly lower than the target condensation temperature Tcm. When the threshold values in Table 3 are applied to the condensation temperature difference band 7 in Table 4, the condensation temperature difference band 7 corresponds to a band of Tcm+5<Tc. That is, the condensation temperature difference band 7 corresponds to a temperature difference band in which the current condensation temperature Tc is significantly higher than the target condensation temperature Tcm. When the threshold values in Table 3 are applied to the condensation temperature difference band 4 in Table 4, the condensation temperature difference band 4 corresponds to the band of Tcm-1<Tc≤Tcm+1. That is, the condensation temperature difference band 4 corresponds to a band in which the current condensation temperature Tc is close to the target condensation temperature Tcm. Between the condensation temperature difference band 1 and the condensation temperature difference band 4, a band in which the current condensation temperature Tc is lower than the target condensation temperature Tcm is defined in stages. Between the condensation temperature difference band 4 and the condensation temperature difference band 7, a band in which the current condensation temperature Tc is higher than the target condensation temperature Tcm is defined stepwise.

In the above example, the target condensation temperature Tcm is corrected to 39°C. If the current condensation temperature Tc is 41° C., the difference between Tc and Tcm is 41° C.-39° C.=2° C. Therefore, from Table 4, the condensation temperature difference band is 5.

Next, in step S11-2, the outdoor unit control means 19 determines the rotation speed step of the outdoor fan motor 5. FIG. 11 is a graph of rotation speed steps showing control of the rotation speed of the outdoor fan motor. In FIG. 11, the horizontal axis indicates the condensation temperature difference band shown in Table 4, and the vertical axis indicates the rotation speed of the outdoor fan motor 5. The number of rotations of the outdoor fan motor 5 is set stepwise in accordance with the increase and decrease of the condensation temperature difference band. That is, as the condensation temperature difference band increases from 1 to 7, the rotation speed of the outdoor fan motor 5 gradually increases, and as the condensation temperature difference band decreases from 7 to 1, the outdoor fan motor 5 increases. The number of rotations of is gradually decreasing. Further, the control of the rotation speed of the outdoor fan motor 5 is provided with hysteresis. That is, upper and lower steps are set to the rotation speed steps corresponding to the respective condensation temperature difference bands. For example, the rotation speed of the upper step n (upper) of the condensation temperature difference band 4 and the rotation speed of the lower step n+1 of the condensation temperature difference band 5 are the same, and the rotation speed of the lower step n (lower) of the condensation temperature difference band 4 is the same. ) And the rotation speed of the rotation speed step n-1 in the upper stage of the condensation temperature difference band 4 are the same. In the present embodiment, the initial position of the rotation speed step is set to the lower stage of the rotation speed step corresponding to the condensation temperature difference band.

For example, when the condensation temperature Tc is 41° C., the target condensation temperature Tcm is 39° C., ΔTc is 2° C., and the condensation temperature difference band is 5 as described above, the rotation speed step is n+1 (lower) which is the lower stage of n+1. Is set to.

In step S11-3, the outdoor unit control means 19 rotates the outdoor fan motor 5 at a rotation speed corresponding to the rotation speed step set in step S11-2, and determines the rotation speed of the outdoor fan 4.

Next, in step S12 of FIG. 4, it is checked whether or not a predetermined time, for example, 60 seconds has elapsed. When the predetermined time has elapsed, the process proceeds to step S13. In step S13, a process of changing the rotation speed of the outdoor fan 4 is executed. FIG. 12 is a flowchart showing a processing procedure for changing the rotation speed of the outdoor fan motor. In step S13-1, the outdoor unit control means 19 extracts the condensation temperature difference band and the hysteresis position where the rotation speed of the outdoor fan motor 5 is stable. Next, in step S13-2, the outdoor unit control means 19 calculates the difference ΔTc between the current condensation temperature Tc and the target condensation temperature Tcm. When the refrigerating cycle in operation is two systems, the condensing temperature Tc is the condensing temperature obtained by the temperature detecting means 13 in the refrigerating cycle system set as the reference system in step S7-1. Then, the outdoor unit control means 19 changes the above-mentioned condensation temperature difference band according to ΔTc.

Next, the process proceeds to step S13-3, and the outdoor unit control means 19 changes the rotation speed of the outdoor fan motor 5 in the following four modes according to the results of step S13-1 and step S13-2.

In step S13-1, it is confirmed that the current rotation speed of the outdoor fan motor 5 is in the upper stage of the hysteresis of the rotation speed step shown in FIG. 11, and in step S13-2, the condensation temperature difference band has a smaller band. That is, when it is confirmed that the band has moved to the lower band, the rotation speed of the outdoor fan motor 5 is decreased and moved to the lower stage of the hysteresis of the rotation speed step. For example, it is confirmed in step S13-1 that the current rotation speed of the outdoor fan motor 5 is n+1 (upper), and ΔTc calculated in step S13-2 is calculated from the condensation temperature difference band 5 to the condensation temperature difference band 5. When it is confirmed that the band 4 has been transferred, the rotation speed of the outdoor fan motor 5 is reduced and moved to n+1 (down).

In addition, when it is confirmed in step S13-2 that the condensation temperature difference band has moved to a smaller number band, that is, the lower band, the rotation speed of the outdoor fan motor 5 is increased, and the upper stage of hysteresis of the rotation speed step. Move to.

Further, the difference ΔTc calculated in step S13-2 is in the condensation temperature difference band corresponding to any of the rotation speed steps n-1 to n-3, and there is no change in the condensation temperature difference band for 60 seconds. When the time has elapsed, the rotation speed of the outdoor fan motor 5 is reduced.

Further, when the difference ΔTc calculated in step S13-2 is in the condensation temperature difference band corresponding to any of the rotation speed steps n+1 to n+3 and the state in which there is no change in the condensation temperature difference band has passed for 60 seconds, Increase the rotation speed of the outdoor fan motor 5.

When any of the above four controls is executed in step S13-3, the process proceeds to step S14 in FIG. In step S14, it is checked whether or not the number of operating indoor units Y or the number of operating systems of the refrigeration cycle has changed. When it is confirmed that the number of operating indoor units Y or the number of operating systems of the refrigeration cycle has changed, the process proceeds to step S2 in FIG. If it is confirmed that there is no change in the number of operating indoor units Y or the number of operating systems of the refrigeration cycle, the process proceeds to step S12.

As described above, according to the present embodiment, even when the air conditioning loads of the first system A and the second system B are different, the rotation speed of the outdoor fan motor 5 is controlled as described above. Therefore, there is no possibility of causing a state in which the degree of supercooling is excessive in each system or a state in which the degree of supercooling is insufficient. As a result, in each system, an operation with excessive capacity or an operation with a shortage of capacity is prevented, and a balanced cooling operation can be executed in the entire air conditioner.

According to the present embodiment, the single outdoor fan 4 and the single outdoor fan motor 5 can improve the cooling operation of the first system A and the second system B. Therefore, it is not necessary to provide an outdoor fan and an outdoor fan motor in each of the first system A and the second system B, and complicated control is not required.

In the present embodiment, when the number of rotations of the outdoor fan motor 5 is changed based on the difference between the current condensation temperature of the outdoor heat exchanger 3 and the target condensation temperature every 60 seconds after the start of operation, the hysteresis is set. Is controlled. Therefore, hunting can be prevented when driving the outdoor fan motor 5.

In the present embodiment, the single outdoor unit X has a configuration having two refrigeration cycles, but the present invention is not limited to this. Even in a configuration in which a single outdoor unit X has three or more refrigeration cycles, the outdoor unit control means 19 executes the same processing as described above, and exhibits the same effect.

Although the present embodiment has a configuration in which two indoor units Y are connected in each system of the refrigeration cycle, the present invention is not limited to this. The number of indoor units Y connected to each system of the refrigeration cycle may be one or three or more. In the configuration in which a plurality of indoor units Y are connected to one system, the control by the outdoor unit control means 19 described above is more effective.

1 compressor, 1A compressor, 1B compressor, 2 4-way valve, 2A 4-way valve, 2B 4-way valve, 3 outdoor heat exchanger, 3A outdoor heat exchanger, 3B outdoor heat exchanger, 4 outdoor fan, 5 outdoor fan motor , 6 expansion valve, 6A1 expansion valve, 6A2 expansion valve, 6B1 expansion valve, 6B2 expansion valve, 7 condensation temperature difference band, 7Y indoor heat exchanger, 7Y1 indoor heat exchanger, 7Y2 indoor heat exchanger, 7Y3 indoor heat exchanger , 7Y4 indoor heat exchanger, 8Y indoor fan, 9Y indoor fan motor, 10A liquid side valve, 10B liquid side valve, 11A gas side valve, 11B gas side valve, 12A temperature detecting means, 12B temperature detecting means, 13 temperature detecting means , 13A temperature detecting means, 13B temperature detecting means, 14 temperature detecting means, 15A temperature detecting means, 15B temperature detecting means, 16Y temperature detecting means, 17Y temperature detecting means, 17Y1 temperature detecting means, 17Y3 temperature detecting means, 18Y indoor unit control Means, 18Y1 indoor unit control means, 18Y2 indoor control means, 18Y3 indoor unit control means, 18Y4 indoor control means, 19 outdoor unit control means, A first system, B second system, N stable rotation speed, Tc condensing temperature, Tca Condensation temperature, Tcb condensation temperature, Tcm target condensation temperature, Tcm_base target condensation temperature base, Tcmh correction value, X outdoor unit, Y indoor unit, Y1 indoor unit, Y2 indoor unit, Y3 indoor unit, Y4 indoor unit, ΔTc difference.

Claims (6)

With an outdoor unit and multiple indoor units,
The outdoor unit includes a plurality of compressors, a plurality of outdoor heat exchangers, a plurality of flow path switching devices, a plurality of expansion valves, and a single outdoor fan that sends air to the plurality of outdoor heat exchangers. has a single outdoor fan motor for driving the single outdoor fan, an outdoor unit control means for controlling said outdoor unit,
Each of the plurality of indoor units has an indoor heat exchanger,
A refrigeration cycle circuit in which the compressor, the outdoor heat exchanger, the flow path switching device, the expansion valve, and the indoor heat exchanger of some indoor units of the plurality of indoor units are connected by a refrigerant pipe. Is an air conditioner having a plurality of systems,
The outdoor unit control means,
When the refrigeration cycle circuits of the plurality of systems are operated simultaneously,
Obtaining the target condensation temperature of the refrigerant in each of the outdoor heat exchangers of the refrigeration cycle circuit of the plurality of systems,
For each of the plurality of refrigeration cycle circuits, obtain the operating frequency of the compressor,
For each of the plurality of refrigeration cycle circuits, a plurality of frequency bands that are defined in stages corresponding to the height of the operating frequency band of the compressor, and the plurality of frequency bands that are defined for each of the plurality of frequency bands. From the target condensing temperature of the outdoor heat exchanger, the target condensing temperature based on the acquired operating frequency of the compressor, and specify,
The frequency band of the refrigeration cycle circuit having the compressor having the largest operating frequency, and the difference between the frequency band of the refrigeration cycle circuit having the compressor having the smallest operating frequency is calculated,
From among the correction values of the plurality of target condensation temperatures that are defined in stages corresponding to the difference of the frequency band, based on the difference of the calculated frequency band, determine the correction value,
Correct the target condensation temperature of the refrigeration cycle circuit having the compressor with the largest operating frequency with the correction value,
An air conditioner that controls the rotation speed of the single outdoor fan motor so that the condensation temperature of the outdoor heat exchanger becomes the target condensation temperature corrected by the correction value . The air conditioner according to claim 1 , wherein the correction value is defined to increase as the difference between the frequency bands increases. The outdoor unit control means,
When controlling the rotation speed of the single outdoor fan motor based on the difference between the current condensation temperature of the outdoor heat exchanger and the corrected target condensation temperature, the single chamber is provided with hysteresis. the air conditioner according to claim 1 or 2 for controlling the rotational speed of the outer off Anmota. With an outdoor unit and multiple indoor units,
The outdoor unit includes a plurality of compressors, a plurality of outdoor heat exchangers, a plurality of flow path switching devices, a plurality of expansion valves, and a single outdoor fan that sends air to the plurality of outdoor heat exchangers. has a single outdoor fan motor for driving the single outdoor fan,
A refrigeration cycle circuit in which the compressor, the outdoor heat exchanger, the flow path switching device, the expansion valve, and the indoor heat exchanger of some indoor units of the plurality of indoor units are connected by a refrigerant pipe. In an air conditioner with multiple systems,
When the plurality of refrigeration cycle circuits are operated at the same time,
A setting step of setting a target condensing temperature of the refrigerant of the air conditioner,
Look including a motor control step of controlling the rotation of said single outdoor fan motor based on the target condensing temperature,
The setting step is
For each of the plurality of refrigeration cycle circuits, obtain the operating frequency of the compressor,
A plurality of frequency bands that are defined stepwise corresponding to the height of the operating frequency band of the compressor, and a target condensing temperature of the outdoor heat exchanger that is defined for each of the plurality of frequency bands. From each of the plurality of refrigeration cycle circuits, a specific step of specifying the target condensing temperature based on the acquired operating frequency of the compressor,
The frequency band of the refrigeration cycle circuit having the compressor having the largest operating frequency, and a band difference calculation step of calculating a difference between the frequency band of the refrigeration cycle circuit having the compressor having the smallest operating frequency,
Based on the difference between the frequency bands calculated in the band difference calculation step, from among the plurality of correction values of the target condensation temperature that are defined stepwise corresponding to the difference between the frequency bands, the correction is performed. A correction value determination step for determining the value,
A step of correcting the target condensing temperature of the refrigeration cycle circuit having the compressor having the highest operating frequency with the correction value . The motor control step is
A current condensation temperature of the outdoor heat exchanger, a temperature difference detection step of detecting a difference between the target condensation temperature corrected in the correction step,
Based on the difference detected in the temperature difference detection step, the rotation speed of the single outdoor fan motor is controlled so that the condensation temperature of the outdoor heat exchanger becomes the target condensation temperature corrected in the correction step. 5. The fan speed control method for an air conditioner according to claim 4 , further comprising: The fan speed control method for an air conditioner according to claim 5 , wherein in the rotation speed control step, the rotation speed of the single outdoor fan motor is controlled with a hysteresis.

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