KR20210131237A - Air conditioner system and control method - Google Patents

Abstract

A system and a method capable of suppressing intermittent driving and maintaining comfort are provided. According to the present invention, an air conditioning system comprises an indoor unit and an outdoor unit. The indoor unit includes a heat exchanger, an indoor temperature detection means for detecting the temperature of the room, and a valve for adjusting a flow rate of a refrigerant flowing in a refrigeration cycle. The outdoor unit includes a heat exchanger, a compressor, and a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle. In addition, the air conditioning system comprises a control means for controlling the opening degree of the valve of the indoor unit according to the indoor temperature detected by the indoor temperature detection means and the amount of change in the temperature in the room in a predetermined time.

Description

AIR CONDITIONER SYSTEM AND CONTROL METHOD

The present invention relates to an air conditioning system and a method for controlling the operation of the air conditioning system.

In the conventional air conditioning system, a method of adjusting the room temperature by controlling the compressor frequency of the outdoor unit according to the load of the indoor unit is widely adopted. When the compressor of the outdoor unit has an operable frequency range, the load of the indoor unit is small, and the compressor cannot maintain room temperature even when the compressor operates at the lowest operating frequency, the compressor is stopped (thermo-off) and the compressor is operated (thermo-on). Repeated operation, so-called intermittent operation, is performed to stabilize room temperature.

However, intermittent operation has a problem that there is a vertical fluctuation in room temperature, impairing comfort, and lowering the efficiency of equipment compared to continuous operation.

Then, for the purpose of avoiding intermittent operation, there is known a technique of temporarily lowering the frequency to the lowest operating frequency lower than the starting operating frequency or in a range equal to or higher than the lower limit operating frequency for use of the compressor (for example, Patent Document 1, see 2). A technique for reducing the refrigerant circulation amount by reducing the opening degree of the expansion valve of the outdoor unit is also known (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 2011-202885 Japanese Patent Laid-Open No. 2015-102252 Japanese Patent Laid-Open No. 10-141740

However, in the techniques described in Patent Documents 1 and 2, there is a problem that intermittent operation cannot be avoided when the compressor frequency required for maintaining the room temperature at the set temperature becomes lower than the lower limit operating frequency for use of the compressor. there was.

In the technique described in Patent Document 3, since the opening degree of the expansion valve of the outdoor unit is forcibly reduced to reduce the refrigerant circulation amount and thereby lower the capacity, when a plurality of indoor units are connected, the cooling capacity of all indoor units is reduced. let it go Therefore, when the indoor unit is located in a room with a different load, the room temperature cannot be maintained in the room with a large load, and there is a problem that comfort cannot be maintained.

In view of the above problems, the present invention provides an air conditioning system including an indoor unit and an outdoor unit,

indoor unit,

heat exchanger and

indoor temperature detecting means for detecting the indoor temperature;

a valve for regulating the flow rate of refrigerant flowing in the refrigeration cycle;

outdoor unit,

heat exchanger and

compressor and

a valve for regulating the flow rate of refrigerant flowing in the refrigeration cycle;

An air conditioning system is provided, comprising control means for controlling an opening degree of a valve of an indoor unit according to the temperature of the room detected by the room temperature detecting means and the amount of change in the temperature of the room in a predetermined time.

ADVANTAGE OF THE INVENTION According to this invention, it also becomes possible to suppress an intermittent operation and to maintain comfort.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the 1st structural example of an air conditioning system.
Fig. 2 is a diagram illustrating a hardware configuration of a control device included in the air conditioning system;
Fig. 3 is a flowchart showing a first example of opening degree control of an indoor expansion valve;
Fig. 4 is a diagram showing time histories of power consumption after the start of operation in the conventional control and the present control;
Fig. 5 is a flowchart showing a second example of opening degree control of an indoor expansion valve;
Fig. 6 is a flowchart showing a third example of opening degree control of the indoor expansion valve;
Fig. 7 is a flowchart showing a fourth example of opening degree control of the indoor expansion valve;
Fig. 8 is a diagram showing a second configuration example of the air conditioning system;
Fig. 9 is a flowchart showing a fifth example of opening degree control of the indoor expansion valve;
Fig. 10 is a flowchart showing a sixth example of opening degree control of an indoor expansion valve;
Fig. 11 is a flowchart showing a seventh example of controlling the opening degree of the indoor expansion valve;
Fig. 12 is a flowchart showing an eighth example of opening degree control of the indoor expansion valve;

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the 1st structural example of an air conditioning system. The air conditioning system includes an indoor unit 10 installed indoors, such as a house or a building, and an outdoor unit 20 installed outdoors. The air conditioning system may include an operation device (remote controller) for operating the indoor unit by wirelessly communicating with the indoor unit 10 in a room in which the indoor unit 10 is installed.

The indoor unit 10 and the outdoor unit 20 are connected by two pipes 30 and 31 through which a refrigerant as a heat medium circulates. As the refrigerant, for example, hydrofluorocarbon such as R410a or R32 is used. In addition, the indoor unit 10 and the outdoor unit 20 are connected by a communication cable or the like in order to communicate with each other. In addition, the indoor unit 10 and the outdoor unit 20 are not limited to being connected by wire using a communication cable or the like, and may be connected wirelessly using WiFi (registered trademark) or the like.

The indoor unit 10 starts or stops in response to a user's operation. When the indoor unit 10 is started, it commands the outdoor unit 20 to start, and notifies the set temperature set in the indoor unit 10, the measured room temperature, and the like. The indoor unit 10 also notifies the outdoor unit 20 of the changed operating conditions when the user receives a change in operating conditions, such as an operating mode or a set temperature. When the indoor unit 10 stops, it commands the outdoor unit 20 to stop its operation.

The indoor unit 10 introduces indoor air during operation, exchanges heat between the introduced air and the refrigerant supplied from the outdoor unit 20 , and blows the cooled or warmed air to bring the room to a set temperature. Cool or warm as much as possible.

For this reason, the indoor unit 10 includes a heat exchanger 11 that exchanges heat between indoor air and a refrigerant, and indoor air is introduced into the heat exchanger 11 and the air heat-exchanged by the heat exchanger 11 is removed. A blower (fan) 12 that blows out is provided.

The indoor unit 10 includes indoor temperature detecting means for detecting the indoor temperature in order to notify the indoor temperature to the outdoor unit 20 . As the room temperature detection means, the room temperature sensor 13 can be used. Moreover, the indoor unit 10 is provided with piping temperature detection means for detecting the outer wall surface temperature of the two piping 30 and 31 connected with the heat exchanger 11 . As piping temperature detection means, the piping temperature sensors 14 and 15 can be used. In addition, the indoor unit 10 includes an indoor expansion valve 16 for expanding the refrigerant and adjusting the flow rate of the refrigerant flowing through the heat exchanger 11 .

When the indoor unit 10 is used for cooling, the heat exchanger 11 functions as an evaporator, and the refrigerant flows into the heat exchanger 11 as a two-phase state (liquid refrigerant) in which liquid and gas are mixed. The refrigerant conducts heat exchange with the air introduced by the fan 12 in the heat exchanger 11 , so that the liquid component is evaporated, discharged from the heat exchanger 11 as a gas refrigerant, and sent to the outdoor unit 20 . The liquid component evaporates at a constant temperature (saturation temperature) corresponding to the pressure in the heat exchanger 11 , and is discharged from the heat exchanger 11 at the saturation temperature or a temperature higher than the saturation temperature. Δt when discharged at a temperature about Δt higher than the saturation temperature indicates a temperature rise from the saturation temperature, and is called a superheat degree.

The outdoor unit 20 receives a designation from the indoor unit 10 and is started, and starts operation in a set operation mode or notified from the indoor unit 10 . The operation mode is a cooling mode, a heating mode, a ventilation mode, and the like. The outdoor unit 20 controls the temperature, pressure, flow rate, etc. of the refrigerant according to a set temperature, an indoor temperature, a pipe temperature, etc. which are set or notified from the indoor unit 10 . In addition, the outdoor unit 20 receives a command from the indoor unit 10 to stop the operation.

The outdoor unit 20 is connected to the indoor unit 10 through pipes 30 and 31 , and circulates a refrigerant. For this reason, a compressor 21 for circulating the refrigerant is provided. The refrigerant gas compressed by the compressor 21 exchanges heat with the air introduced by the fan 23 in the heat exchanger 22 to become a high-pressure liquid refrigerant. In addition, the outdoor unit 20 is provided with a four-way valve 25 for reversing the direction in which the refrigerant flows in order to enable heating operation. The outdoor expansion valve 24 is provided in order to adjust the flow rate of the refrigerant|coolant while making the refrigerant|coolant which became high-pressure state at the time of heating into a low-temperature, low-pressure refrigerant|coolant.

In the compressor 21, the flow rate of the refrigerant is changed by changing the operating frequency.

The outdoor unit 20 includes a control device 26 . The control device 26 controls the operation frequency of the compressor 21 and the outdoor expansion valve 24 based on the indoor temperature detected by the room temperature sensor 13, the set temperature, the piping temperature, and the operation mode. Control the degree of opening. In addition, the four-way valve 25 is switched according to the set operation mode.

The operating frequency of the compressor 21 has a lower limit, and even if the compressor 21 is operated at the lowest operating frequency, when the generating capacity is greater than the indoor load, the indoor temperature cannot be maintained at the set temperature through continuous operation. Therefore, an intermittent operation that repeats thermo-on and thermo-off is performed to maintain the room temperature at the set temperature. However, when intermittent operation is performed, compared to continuous operation, the efficiency and reliability of the device are lowered, and since the room temperature also fluctuates, there is a problem of impairing the comfort.

Accordingly, the outdoor unit 20 includes a frequency sensor 27 as a frequency detection means for detecting the operating frequency of the compressor 21 , and the control device 26 controls the room temperature detected by the room temperature sensor 13 and It is configured to control the degree of opening of the indoor expansion valve 16 according to the amount of change in the room temperature over a predetermined time and the operating frequency detected by the frequency sensor 27 .

The control device 26 reduces the flow rate of the refrigerant flowing into the heat exchanger 11 by reducing the opening degree of the indoor expansion valve 16 when the compressor 21 is operating near the lowest operating frequency. , the generated air conditioning capacity (cooling capacity) is reduced. As a result, even when the compressor 21 is operating at the lowest operating frequency, a further reduction in cooling capacity is possible. You can avoid driving. This detail is demonstrated below.

2 is a diagram showing an example of the hardware configuration of the control device 26 used in the air conditioning system. The control device 26 includes a CPU 40 , a flash memory 41 , a RAM 42 , a communication I/F 43 , and a control I/F 44 . Components such as the CPU 40 are connected to the bus 45 and exchange information and the like via the bus 45 .

The flash memory 41 stores programs executed by the CPU 40, various data, and the like. The RAM 42 provides a work area for the CPU 40 . The CPU 40 realizes the above control by reading and executing the program stored in the flash memory 41 into the RAM 42 .

The communication I/F 43 is connected to the indoor unit 10 and receives information such as an indoor temperature, a liquid piping temperature, and a gas piping temperature from the indoor unit 10 . In addition, the communication I/F 43 also receives information from the frequency sensor 27 . The control I/F 44 is connected to the compressor 21 , the fan 23 , the outdoor expansion valve 24 , the four-way valve 25 , and the indoor expansion valve 16 to control each device.

Here, the control device 26 realizes the control by the CPU 40 reading and executing the program from the flash memory 41, but the control may be realized using hardware such as a circuit.

Specific control will be described in detail below as control during cooling operation. 3 is a flowchart showing a first example of the opening degree control of the indoor expansion valve 16 . This control starts from step 100 at the stage in which the cooling operation is started. In step 101, the driving frequency F is determined whether or not less than the minimum operating frequency F _min greater than any frequency (frequency threshold) F _d. The frequency threshold F _d is determined with a certain margin to the _{minimum operating frequency F min} so that intermittent operation is not entered before starting control of the opening degree of the indoor expansion valve 16 . As for the opening degree control of the indoor expansion valve 16, the determination of step 101 is repeated until it is determined that _{F is smaller than F d.}

If it is determined in step 101 that F is _{smaller than F d} , the process proceeds to step 102 to determine whether the difference RL between the indoor air conditioning load and the generated cooling capacity is smaller than a _{load threshold RL th .}

The difference RL between the indoor air conditioning load and the generation capability can be detected using the set temperature, the detected value (room temperature) detected by the room temperature sensor 13, and the amount of change in the room temperature within a predetermined time. In a short period of time, such as the time taken to control the indoor expansion valve 16 (a few seconds), the change amount is too small and the change amount cannot be detected. Therefore, for example, it can be made with water.

When it _{is determined that RL is equal to or greater than RL th} , the opening degree control of the indoor expansion valve 16 is not performed because the cooling capacity is relatively small with respect to the air conditioning load and there is no need to reduce the capacity. For this reason, it returns to step 101, and control is continued.

On the other hand, _{when it is determined in step 102 that RL is smaller than RL th} , since the cooling capacity is relatively large with respect to the air conditioning load, the flow proceeds to step 103 and the degree of opening of the indoor expansion valve 16 to decrease the flow rate of the refrigerant. make small When the opening degree of the indoor expansion valve 16 is made small, the flow rate of the refrigerant is reduced, and since the pressure is low, the two-phase refrigerant becomes gaseous with a smaller heat exchange amount, so the heat transfer tube functions as an evaporator of the heat exchanger 11 . The partial area (effective area) of is also reduced. Since the air in the room is cooled mainly by latent heat when the refrigerant evaporates, the effective area can be reduced, thereby reducing the cooling capacity. When the cooling capacity is lowered, it is possible to evaporate all of the refrigerant and further to impart a degree of superheat to discharge the refrigerant from the heat exchanger (11).

The control device 26 controls the rotation speed of the compressor 21 based on the set temperature and the detected value of the room temperature sensor 13, and opens the outdoor expansion valve 24 so as to maintain the degree of superheat within a constant range. control the figure Accordingly, when the indoor load is large, the control device 26 increases the rotational speed of the compressor 21 to increase the refrigerant circulation amount, and when the indoor load becomes small, the control device 26 lowers the rotational speed of the compressor 21 to decrease the refrigerant circulation amount. Reduce.

Even when the indoor load gradually decreases and the operation of the compressor 21 reaches the lowest operating frequency, the cooling capacity is lowered by reducing the opening degree of the indoor expansion valve 16 so that the compressor 21 continues at the lowest operating frequency. Even when driving, the room temperature can be maintained. For this reason, it becomes possible to maintain continuous operation of the compressor 21. As shown in FIG.

After the degree of opening of the indoor expansion valve 16 is decreased in step 103, the flow returns to step 101 and the control is continued. In addition, when the operation of the air conditioning system is stopped, this control is also terminated.

4 shows the time history of power consumption after the start of operation in the conventional control and the opening degree control of the indoor expansion valve 16 shown in FIG. 3 . Conventional control is control in which intermittent operation is repeated, and a time history is indicated by a broken line. In the conventional control, power consumption becomes zero when the thermo-off is turned off, but a large amount of power is consumed when the thermo-on is turned on. On the other hand, if the opening degree control (main control) of the indoor expansion valve 16 is performed, the thermo-off/thermo-on does not occur and only a constant low power is consumed, so the total power consumption ( The value of the time integral of the power consumption) becomes smaller than the conventional control total power consumption equally surrounded by the time axis and the broken line. Therefore, this control can reduce power consumption compared with the conventional control.

Although the control shown in Fig. 3 is control only by reducing the opening degree of the indoor expansion valve 16, when the room temperature rises due to an increase in external temperature, etc. and the air conditioning load increases, the reduced cooling capacity is desired there is In addition, if the refrigerant circulation amount is small and the effective area of the evaporator is small when the air conditioning load is increased, the operation becomes inefficient. Therefore, control capable of improving the cooling capacity will be described with reference to FIG. 5 .

5 is a flowchart showing a second example of the opening degree control of the indoor expansion valve 16 . Starts at step 200 and, similarly to the control illustrated in Figure 3, in step 201, it is determined whether the operating frequency F is paper, is smaller than the threshold frequency F _d. If it is determined that F _{is smaller than F d} , the process proceeds to step 202 to determine whether the difference RL between the indoor air conditioning load and the generated cooling capacity is smaller than a _{threshold RL th .} Then, _{when it is determined that RL is smaller than RL th} , the flow advances to step 203 and the degree of opening of the indoor expansion valve 16 is decreased in order to decrease the flow rate of the refrigerant. After the degree of opening of the indoor expansion valve 16 is decreased, the flow returns to step 201 to continue the control.

When it is determined in step 201 that F is _{equal to or greater than F d} , or when it is determined in step 202 that RL is _{greater than or equal to RL th} , the flow advances to step 204 to increase the degree of opening of the indoor expansion valve 16 . When F is F _d or more, it indicates that it is necessary to improve the cooling capacity, and in order to improve the cooling capacity, the amount of circulation of the refrigerant is increased and the superheat degree of the outlet side of the heat exchanger 11 is reduced to increase the effective area. To increase, the opening degree of the indoor expansion valve 16 is made large. When RL is RL _th or higher, it indicates that the air conditioning load is relatively large compared to the generated cooling capacity. , increase the opening degree of the indoor expansion valve 16 to increase the refrigerant circulation amount.

After the degree of opening of the indoor expansion valve 16 is increased, the flow returns to step 201 and control is continued. Also in this case, when the operation of the air conditioning system is stopped, the control is terminated.

Although the control shown in FIG. 5 is a control for decreasing or increasing the opening degree of the indoor expansion valve 16, when the opening degree is greatly changed at one time, the room temperature fluctuates. Note that, depending on the air conditioning load, the room temperature fluctuation may be smaller when the opening degree of the indoor expansion valve 16 is maintained without changing it. It is because a fluctuation|variation generate|occur|produces in room temperature, and when the fluctuation|variation is large, comfort is impaired. Then, the control which can adjust and maintain the opening degree of the indoor expansion valve 16 is demonstrated with reference to FIG.

6 is a flowchart showing a third example of the opening degree control of the indoor expansion valve 16 . Steps 301 and 302 shown in FIG. 6 are the same as steps 201 and 202 shown in FIG. 5 , and therefore their description is omitted.

If it is determined in step 302 that RL is _{smaller than RL th} , the process proceeds to step 303, where it is determined whether or not _{the change amount dT in} of the room temperature in a predetermined time is smaller than the preset opening degree decrease start change amount dT _dec. dT _dec is the amount of change in room temperature serving as a reference for starting the decrease in the opening degree of the indoor expansion valve 16 . In addition, the change amount dT _in of room temperature can be computed as the change amount of the detected value of the room temperature sensor 13 in predetermined time.

If in Step 303 dT _in small determination than dT _dec, since went down to the room temperature abruptly, it is necessary to reduce the cooling capacity, the process proceeds to step 304, in accordance with the amount of change dT _in the room temperature, the indoor expansion valve ( 16) is calculated, and the opening degree of the indoor expansion valve 16 is decreased according to the change amount. Then, the flow returns to step 301, and control is continued.

_{When it is determined in} step 303 that dT in is _{equal to or greater than dT dec} , the process proceeds to step 305 and it is determined whether _{the temperature difference between the room temperature T in} and the set temperature T _set is smaller than a preset opening degree decrease start temperature difference ΔT _{dec .} ΔT _dec is the temperature difference between the room temperature and the set temperature, which is a reference for starting the decrease in the opening degree of the indoor expansion valve 16 . When it is determined that the temperature difference is _{smaller than ΔT dec} , the amount of change in room temperature _{is larger than dT dec} , but since the room temperature is low, it is necessary to reduce the cooling capacity. make it Then, the flow returns to step 301, and control is continued.

On the other hand, if it is determined in step 305 that the temperature difference is _{greater than or equal to ΔT dec} , it can be determined that the room temperature has not decreased, and if control is performed to reduce the opening degree of the indoor expansion valve 16 , the generation capacity is made too small and the room temperature rises. there is a possibility to do For this reason, the flow advances to step 306, and the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the flow returns to step 301, and control is continued.

If it is determined that F is more than F _d in step 301, or if the RL at step 302 determined to be more than RL _th, whether or not the operation proceeds to step 307, dT _in this, a preset opening degree increase start change amount is greater than dT _inc judge dT _inc is the amount of change in room temperature, which is a reference for starting an increase in the opening degree of the indoor expansion valve 16 . When dT _in is _{greater than dT inc} , it indicates that the room temperature is greatly changed due to an increase in outside temperature, etc., so it is necessary to increase the flow rate of the refrigerant by increasing the opening degree of the indoor expansion valve 16 . For this reason, when it _{is determined that dT in} is _{greater than dT inc} , the flow advances to step 308 , the amount of change in the opening degree of the indoor expansion valve 16 is calculated according to the amount of change in the detected value of the room temperature sensor 13 , and the indoor expansion The degree of opening of the valve 16 is increased.

_{When it is determined in} step 307 that dT in is _{equal to or less than dT inc} , the flow advances to step 309 to determine whether _{the temperature difference between the room temperature T in} and the set temperature T _set is larger than a preset opening degree increase start temperature difference ΔT _{inc .} ΔT _inc is the temperature difference between the room temperature and the set temperature, which is a reference for starting an increase in the opening degree of the indoor expansion valve 16 . When the temperature difference is _{greater than ?T inc} , since it is necessary to increase the opening degree of the indoor expansion valve 16 to increase the flow rate of the refrigerant, the flow proceeds to step 308 . On the other hand, _{if the control to increase the opening degree of the indoor expansion valve 16 is performed when the temperature difference is ?T inc} or less, the cooling capacity may be increased and the room temperature may be lowered even though the room temperature has not risen. For this reason, the flow advances to step 310, and the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the flow returns to step 301, and control is continued.

In this way, by controlling and maintaining the opening degree of the indoor expansion valve 16, it is possible to more stabilize the room temperature. Also in this case, when the operation of the air conditioning system is stopped, the control is terminated.

Although the control shown in FIG. 6 is control to adjust and maintain the opening degree of the indoor expansion valve 16, the degree of superheat of the refrigerant on the outlet side of the indoor heat exchanger is obtained by using the detected values of the pipe temperature sensors 14 and 15. It becomes possible to control with the target value. Then, control using the detection values of the piping temperature sensors 14 and 15 is demonstrated with reference to FIG.

7 is a flowchart showing a fourth example of the opening degree control of the indoor expansion valve 16 . Also in this case, only the parts different from the processing shown in FIG. 5 will be described. In step 403, it is determined whether the dT _in superheat increases less than the start change amount dT _inc. In the example shown in FIG. 6, dT _inc was the opening degree increase start change amount, but it is set as the superheat degree increase start change amount in this example. Similarly, in this example, dT _dec is the superheat degree decrease start change amount, ΔT _inc is the superheat degree increase start temperature difference, and ΔT _dec is the superheat degree decrease start temperature difference.

dT _inc is the amount of change in room temperature that is a reference for initiating an increase in the degree of superheat, and dT _des is the amount of change in room temperature that is a reference for initiating a decrease in the degree of superheat. ΔT _inc is the temperature difference between the room temperature and the set temperature, which is a standard for starting the increase in the superheat degree, and ΔT _dec is the temperature difference between the room temperature and the set temperature, which is the standard for starting the decrease in the superheat degree.

In step 404, based on the detected value of the room temperature sensor 13 and the amount of change in the detected value of the room temperature sensor 13 over a predetermined time, the target superheat degree of the refrigerant outlet side of the heat exchanger 11 is calculated. . In this case, since the cooling capacity is reduced by reducing the flow rate of the refrigerant and reducing the effective area by giving the superheat degree, the superheat degree is increased.

In step 405, the amount of change in the opening degree of the indoor expansion valve 16 is calculated so that the refrigerant superheat degree at the outlet side of the indoor heat exchanger becomes the target superheat degree obtained in step 404, and the opening degree of the indoor expansion valve 16 is controlled. . Here, the degree of opening of the indoor expansion valve 16 is reduced. Then, the flow returns to step 401 and control is continued.

_{If it is determined in} step 406 that the temperature difference between T in and T _{set is smaller than ΔT inc} , the flow advances to step 404. If it is determined _{in step 406 that the temperature difference between T in} and T _set is _{equal to or greater than ΔT inc} , the process proceeds to step 407 . In step 407, the target superheat degree is calculated in the same manner as in step 404, but since the cooling capacity is not reduced, the superheat degree is maintained at the current superheat degree. In step 408, the opening degree of the indoor expansion valve 16 is set maintain an open degree of Then, the flow returns to step 401 and control is continued.

_{If it is determined in} step 409 that dT in is _{greater than dT dec} , the flow advances to step 410 to calculate a target superheat degree in the same manner as in step 404. In this case, since the cooling capacity is improved by increasing the flow rate of the refrigerant and increasing the effective area by reducing the degree of superheat, the degree of superheat is reduced.

In step 411, in the same manner as in step 405, the amount of change in the opening degree of the indoor expansion valve 16 at which the refrigerant superheat degree on the outlet side of the indoor heat exchanger becomes the target superheat degree obtained in step 410 is calculated, and the indoor expansion valve 16 control the degree of opening of In this case, the opening degree of the indoor expansion valve 16 is increased. Then, the flow returns to step 401 and control is continued.

_{If it is determined in} step 412 that the temperature difference between T in and T _{set is equal to or less than ΔT dec} , the process proceeds to step 410. If it is determined _{in step 412 that the temperature difference between T in} and T _set is greater than ΔT _dec , the process proceeds to step 413. In step 413, in the same manner as in step 404, the target superheat degree is calculated, but since the cooling capacity is not increased, the superheat degree is maintained at the current superheat degree. In step 414, the opening degree of the indoor expansion valve 16 is set to the current maintain an open degree of Then, the flow returns to step 401 and control is continued. Also in this case, when the operation of the air conditioning system is stopped, the control is terminated.

So far, it has been described that the control device 26 included in the outdoor unit 20 controls the opening degree of the indoor expansion valve 16. However, the degree of opening of the indoor expansion valve 16 is controlled by the control device ( 26) is not limited to what is carried out. For example, it may be implemented by the control apparatus with which the indoor unit 10 is equipped, and you may implement by the centralized control apparatus etc. provided separately from the indoor unit 10 and the outdoor unit 20 .

The air conditioning system is not limited to one in which the indoor unit 10 and the outdoor unit 20 are configured one by one. Accordingly, a system in which a plurality of indoor units 10 are connected to one outdoor unit 20 or a system in which a plurality of outdoor units 20 and a plurality of indoor units 10 are connected may be used. FIG. 8 shows an example of a system in which a plurality of indoor units 10 are connected to one outdoor unit 20 . In the example shown in Fig. 8, three indoor units 10a to 10c and an outdoor unit 20 are connected.

Each of the indoor units 10a to 10c is installed in each room, and the room temperature of each room is adjusted so that it may become a set temperature. Since each of the indoor units 10a to 10c is provided with the indoor expansion valves 16a to 16c, respectively, the cooling capacity can be adjusted for each room. For this reason, even when the air conditioning load differs for each room, the room temperature of each room can be stabilized, avoiding an intermittent operation.

By avoiding intermittent operation and realizing continuous operation, power consumption can be reduced, and the number of starts and stops can be reduced, so that the efficiency of the device can be improved, and failures, etc. are also reduced, so that reliability can be improved. may be Moreover, since room temperature can be stabilized, comfort can be maintained.

In the example described so far, when the operating frequency F of the compressor 21 is detected, the detected operating frequency F is _{smaller than the frequency threshold F d} , and the difference RL between the air conditioning load and the capability is smaller than the _{load threshold RL th} Thus, the opening degree of the indoor expansion valve 16 was controlled. Therefore, there are a plurality of indoor units 10, for example, except for _{one indoor unit 10, even if the difference RL between the air conditioning load and the capability is smaller than the load threshold RL th} , the load on the one indoor unit 10 is large. , F _{exceeds F d} , the opening degree control of the indoor expansion valve 16 is not uniformly performed. With this, room temperature cannot be stabilized and comfort cannot be maintained.

Then, in the opening degree control shown in FIGS. 3 and 5-7, step 101, step 201, step 301, and step 401 are set as the opening degree control deleted, and the difference RL is smaller than the _{load threshold value RL th.} It is possible to control the degree of opening of the indoor expansion valve 16 only by determining . 9-12, each opening degree control is shown as 5th - 8th examples.

9 is a flowchart showing a fifth example of the opening degree control of the indoor expansion valve 16 . This control starts from step 500 at the stage in which the cooling operation is started. In step 501, the operating frequency F is not determined whether the frequency is less than the threshold value F _d, the difference RL of the indoor air conditioning load and the cooling capacity occurs, it is determined only whether a load is less than the threshold value _th RL. Since step 502 is the same as step 103 of FIG. 3 , the description thereof is omitted here.

10 is a flowchart showing a sixth example of the opening degree control of the indoor expansion valve 16 . It starts from step 600, and in step 601, similarly to the example shown in FIG. 9, it is determined whether the _{difference RL is smaller than load threshold value RL th.} The processing after step 602 is the same as the processing after step 203 in FIG. 5 .

11 is a flowchart showing a seventh example of controlling the opening degree of the indoor expansion valve 16. As shown in FIG. It starts from step 700, and in step 701, similarly to the example shown to FIG. 9 and FIG. 10, it is determined whether the _{difference RL is smaller than load threshold value RL th.} The processing after step 702 is the same as the processing after step 303 of FIG. 6 .

12 is a flowchart showing an eighth example of the opening degree control of the indoor expansion valve 16 . Starts at step 800 and, in step 801, similar to the one shown in Figs. 9 to 11, it is determined whether or not the difference RL, RL is smaller than the load threshold _th. The processing after step 802 is the same as the processing after step 403 in FIG. 7 .

As in the example shown in Figs. 9 to 12, _{only by determining whether the difference RL is smaller than the load threshold RL th} , this control can be operated irrespective of the current operating frequency. Accordingly, it is avoided that the opening degree control of the indoor expansion valve 16 is not uniformly performed, and the opening degree control is appropriately performed for the indoor expansion valve 16 of the indoor unit 10 _{whose RL is smaller than RL th.} By doing so, it becomes possible to stabilize room temperature and maintain comfort.

Although the indoor unit, air conditioning system, and control method of the present invention have been described in detail with the above-described embodiment, the present invention is not limited to the above-described embodiment, and other embodiments, additions, changes, deletions, etc. , it can be changed within the range that a person skilled in the art can imagine, and is included in the scope of the present invention as long as the action and effect of the present invention are exhibited in any aspect.

10, 10a to 10c: indoor unit
11, 11a to 11c: heat exchanger
12, 12a to 12c: fan
13, 13a to 13c: room temperature sensor
14, 14a to 14c, 15, 15a to 15c: pipe temperature sensor
16, 16a to 16c: indoor expansion valve
20: outdoor unit
21: compressor
22: heat exchanger
23: fan
24: outdoor expansion valve
25: four-way valve
26: control device
27: frequency sensor
30, 31: piping
40: CPU
41: flash memory
42: RAM
43: Communication I/F
44: control I/F
45: bus

Claims (11)

It is an air conditioning system having an indoor unit and an outdoor unit,
the indoor unit,
heat exchanger and
indoor temperature detecting means for detecting the indoor temperature;
a valve for regulating the flow rate of refrigerant flowing in the refrigeration cycle;
the outdoor unit,
heat exchanger and
compressor and
a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle;
and control means for controlling an opening degree of the valve of the indoor unit according to the temperature of the room detected by the room temperature detecting means and the amount of change in the temperature of the room in a predetermined time. According to claim 1,
The control means detects the difference between the air conditioning load and the air conditioning capability from the difference between the indoor temperature and the set temperature detected by the indoor temperature detection means and the amount of change in the indoor temperature in the predetermined time, and controlling to reduce an opening degree of the valve of the indoor unit when the difference is smaller than a load threshold. According to claim 1,
The control means detects the difference between the air conditioning load and the air conditioning capability from the difference between the indoor temperature and the set temperature detected by the indoor temperature detection means and the amount of change in the indoor temperature in the predetermined time, and controlling to increase the opening degree of the valve of the indoor unit when the difference is equal to or greater than a load threshold. 4. The method according to any one of claims 1 to 3,
wherein the control means calculates a change amount of an opening degree of the valve of the indoor unit based on the indoor temperature detected by the indoor temperature detecting means and a change amount of the indoor temperature in the predetermined time. harmonization system. 5. The method of claim 4,
The indoor unit,
two pipe temperature detection means for detecting respective temperatures of two pipes connecting the heat exchanger and the outdoor unit;
The control means calculates a target superheat degree of the refrigerant discharged from the heat exchanger based on the temperature of the room detected by the room temperature detecting means and the amount of change in the temperature of the room at the predetermined time, and a superheat degree obtained from a difference between the two temperatures detected by the two pipe temperature detecting means calculates a change amount of an opening degree of the valve of the indoor unit such that the calculated target superheat degree. An air conditioning system having a plurality of indoor units and outdoor units,
Each of the indoor units,
heat exchanger and
indoor temperature detecting means for detecting the indoor temperature;
a valve for regulating the flow rate of refrigerant flowing in the refrigeration cycle;
the outdoor unit,
heat exchanger and
compressor and
a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle;
Control for controlling the opening degree of each valve of each indoor unit in accordance with the temperature of each of the indoor units detected by the respective indoor temperature detecting means of each of the indoor units and the amount of change in the temperature of each of the respective rooms in a predetermined time An air conditioning system comprising means. 7. The method of claim 6,
The control means is configured to determine, for one or more of the indoor units, a difference between an air conditioning load and an air conditioning capability between a difference between the indoor temperature detected by the indoor temperature detecting means and a set temperature, and the indoor temperature at the predetermined time. An air conditioning system which detects from the amount of change, and performs control to decrease the opening degree of the valve of the indoor unit when the detected difference is smaller than a load threshold. 7. The method of claim 6,
The control means is configured to determine, for one or more of the indoor units, a difference between an air conditioning load and an air conditioning capability between a difference between the indoor temperature detected by the indoor temperature detecting means and a set temperature, and the indoor temperature at the predetermined time. An air conditioning system which detects from a change amount and performs control to increase the opening degree of the valve of the indoor unit when the detected difference is equal to or greater than a load threshold. 9. The method according to any one of claims 6 to 8,
The control means, for one or more of the indoor units, based on the indoor temperature detected by the indoor temperature detecting means of the indoor unit and the amount of change in the indoor temperature in the predetermined time, the valve of the indoor unit To calculate the amount of change in the opening of the air conditioning system. 10. The method of claim 9,
Each of the indoor units,
two pipe temperature detection means for detecting respective temperatures of two pipes connecting the heat exchanger and the outdoor unit;
The control means, for one or more of the indoor units, based on the indoor temperature detected by the indoor temperature detecting means of the indoor unit and the amount of change in the indoor temperature in the predetermined time, the heat exchange of the indoor unit. The target superheat degree of the refrigerant discharged from the unit is calculated, and the superheat degree obtained from the difference between the two temperatures detected by the two pipe temperature detecting means of the indoor unit is the calculated target superheat degree. An air conditioning system that calculates the amount of change in the opening of a valve. An indoor unit including a heat exchanger, indoor temperature detecting means for detecting the temperature of the room, and a valve for adjusting a flow rate of a refrigerant flowing in a refrigeration cycle;
An outdoor unit including a heat exchanger, a compressor, and a valve for adjusting a flow rate of a refrigerant flowing in a refrigeration cycle;
A control method executed by said control means of an air conditioning system comprising control means,
calculating an amount of change in the temperature of the room in a predetermined time from the temperature of the room detected by the room temperature detecting means;
and controlling the opening degree of the valve of the indoor unit according to the temperature of the room detected by the room temperature detecting means and the calculated amount of change in the room temperature.

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