WO2021214931A1

WO2021214931A1 - Air conditioning system and control method

Info

Publication number: WO2021214931A1
Application number: PCT/JP2020/017449
Authority: WO
Inventors: 悟中安; 浦田　和幹; 太樹飯塚; 幹人徳地
Original assignee: 日立ジョンソンコントロールズ空調株式会社
Priority date: 2020-04-23
Filing date: 2020-04-23
Publication date: 2021-10-28
Also published as: JPWO2021214931A1; CN113551437A; KR102558826B1; KR20210131237A; JP6890706B1; JP6890727B1; CN113551437B; JP2021173518A

Abstract

Provided are a system and a method which can prevent or reduce an intermittent operation and maintain comfort. This air conditioning system includes an indoor unit and an outdoor unit. The indoor unit includes: a heat exchanger; an indoor temperature detection means for detecting an indoor temperature; and a valve for adjusting the flow rate of a refrigerant flowing in a refrigeration cycle. The outdoor unit includes: a heat exchanger; a compressor; a frequency detection means for detecting the operation frequency of the compressor; and a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle. The air conditioning system further includes a control means for controlling the opening degree of the valve of the indoor unit depending on the indoor temperature detected by the indoor temperature detection means, the amount of change in the indoor temperature over a predetermined period of time, and the operation frequency detected by the frequency detection means.

Description

Air conditioning system and control method

The present invention relates to an air conditioning system and a method of 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. If the compressor of the outdoor unit has an operable frequency range, the load of the indoor unit is small, and the room temperature cannot be maintained even if the compressor operates at the lowest operating frequency, the compressor is stopped (thermo-off) and compressed. The room temperature is stabilized by repeating the operation (thermo-on) of the machine, so-called intermittent operation.

However, intermittent operation has the problem that the room temperature fluctuates up and down, impairs comfort, and reduces the efficiency of the equipment compared to continuous operation.

Therefore, 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 the range of the lower limit operating frequency for use of the compressor (for example). See Patent Documents 1 and 2). Further, there is also known a technique of reducing the opening degree of the expansion valve of the outdoor unit to reduce the amount of refrigerant circulating (see, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 2011-202885 Japanese Unexamined Patent Publication No. 2015-102252 Japanese Unexamined Patent Publication No. 10-141740

However, in the techniques described in Patent Documents 1 and 2 described above, when the compressor frequency required to keep the room temperature at the set temperature is lower than the lower limit operating frequency in use of the compressor, intermittent operation is performed. There was a problem that it could not be avoided.

In the technique described in Patent Document 3 above, in order to forcibly reduce the opening degree of the expansion valve of the outdoor unit and reduce the amount of refrigerant circulation to reduce the capacity, when a plurality of indoor units are connected. Reduces the cooling capacity of all indoor units. Therefore, when the indoor unit is located in a room having a different load, it is not possible to maintain the room temperature in the room having a large load, and there is a problem that the comfort cannot be maintained.

The present invention is an air conditioning system including an indoor unit and an outdoor unit in view of the above problems.
The indoor unit
With a heat exchanger
Indoor temperature detecting means for detecting indoor temperature and
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle,
The outdoor unit
With a heat exchanger
With a compressor,
Frequency detection means to detect the operating frequency of the compressor,
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle,
Control to control the valve opening of the indoor unit according to the indoor temperature detected by the indoor temperature detecting means, the amount of change in the indoor temperature in a predetermined time, and the operating frequency detected by the frequency detecting means. An air conditioning system, including means, is provided.

According to the present invention, it is possible to suppress intermittent operation and maintain comfort.

The figure which showed the 1st configuration example of the air conditioning system. The figure which illustrated the hardware composition of the control device provided in the air conditioning system. The flowchart which showed the 1st example of the opening degree control of an indoor expansion valve. The figure which showed the time history of the power consumption after the start of operation in the conventional control and this control. The flowchart which showed the 2nd example of the opening degree control of an indoor expansion valve. The flowchart which showed the 3rd example of the opening degree control of an indoor expansion valve. The flowchart which showed the 4th example of the opening degree control of an indoor expansion valve. The figure which showed the 2nd configuration example of the air conditioning system.

FIG. 1 is a diagram showing a first configuration example of an air conditioning system. The air conditioning system includes an indoor unit 10 installed indoors of a house or a building, and an outdoor unit 20 installed outdoors. The air conditioning system can include an operating device (remote controller) for operating the indoor unit by wirelessly communicating with the indoor unit 10 in the room where 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, hydrofluorocarbons such as R410a and R32 are used. Further, 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. The indoor unit 10 and the outdoor unit 20 are not limited to being wiredly connected by a communication cable or the like, and may be wirelessly connected by using WiFi (registered trademark) or the like.

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

The indoor unit 10 takes in indoor air during operation, exchanges heat between the taken-in air and the refrigerant supplied from the outdoor unit 20, and blows out cooled air or warmed air to set the room. Cool or warm to temperature.

Therefore, the indoor unit 10 takes in the heat exchanger 11 that exchanges heat between the indoor air and the refrigerant, and the indoor air into the heat exchanger 11, and blows out the heat exchanged air by the heat exchanger 11. It is equipped with a blower (fan) 12.

The indoor unit 10 includes an indoor temperature detecting means for detecting the indoor temperature in order to notify the outdoor unit 20 of the indoor temperature. As the room temperature detecting means, the room temperature sensor 13 can be used. Further, the indoor unit 10 includes a pipe temperature detecting means for detecting the outer wall surface temperature of the two

pipes

30 and 31 connected to the heat exchanger 11. As the pipe temperature detecting means, the

pipe temperature sensors

14 and 15 can be used. Further, 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 as a cooler, the heat exchanger 11 functions as an evaporator, and the refrigerant flows into the heat exchanger 11 in a two-phase flow state (liquid refrigerant) in which liquid and gas are mixed. The refrigerant exchanges heat with the air taken in by the fan 12 in the heat exchanger 11, so that the liquid component evaporates, is discharged from the heat exchanger 11 as a gas refrigerant, and is 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 a saturation temperature or a temperature higher than the saturation temperature. When discharged at a temperature higher than the saturation temperature by Δt, Δt indicates a temperature rise from the saturation temperature and is called a degree of superheat.

The outdoor unit 20 starts in response to the designation from the indoor unit 10, and starts the operation in the set or notified operation mode from the indoor unit 10. The operation mode is a cooling mode, a heating mode, a ventilation mode, or the like. The outdoor unit 20 controls the temperature, pressure, flow rate, etc. of the refrigerant according to the set temperature, the indoor temperature, the piping temperature, etc., which are set or notified from the indoor unit 10. Further, the outdoor unit 20 stops its operation in response to a command from the indoor unit 10.

The outdoor unit 20 is connected to the indoor unit 10 via

pipes

30 and 31, and circulates the refrigerant. Therefore, a compressor 21 for circulating the refrigerant is provided. The refrigerant gas compressed by the compressor 21 exchanges heat with the air taken in by the fan 23 in the heat exchanger 22 to become a high-pressure liquid refrigerant. Further, 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 the heating operation. The outdoor expansion valve 24 is provided to change the refrigerant that has been in a high pressure state during heating into a low temperature and low pressure refrigerant and to adjust the flow rate of the refrigerant.

The compressor 21 can change the flow rate of the refrigerant by changing the operating frequency.

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

There is a lower limit to the operating frequency of the compressor 21, and even if the compressor 21 operates at the lowest operating frequency, if the generation capacity is larger than the indoor load, the indoor temperature cannot be maintained at the set temperature by continuous operation. .. Therefore, the room temperature is maintained at the set temperature by performing an intermittent operation in which the thermo-on and the thermo-off are repeated. However, when the intermittent operation is performed, the efficiency and reliability of the device are lowered as compared with the continuous operation, and the room temperature also fluctuates, so that there is a problem that the comfort is impaired.

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

When the compressor 21 is operating near the minimum operating frequency, the control device 26 reduces the opening degree of the indoor expansion valve 16 to reduce the flow rate of the refrigerant flowing into the heat exchanger 11, resulting in air conditioning. Reduce the capacity (cooling capacity). As a result, even if the compressor 21 is operating at the lowest operating frequency, the cooling capacity can be further reduced. Therefore, even if the air conditioning load conventionally requires intermittent operation of the compressor 21, the compressor 21 can be operated. Intermittent operation can be avoided. The details will be described below.

FIG. 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 / F43, and a control I / F44. Components such as the CPU 40 are connected to the bus 45, and information and the like are exchanged via the bus 45.

The flash memory 41 stores a program 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 the indoor temperature, the liquid pipe temperature, and the gas pipe temperature from the indoor unit 10. The communication I / F 43 also receives information from the frequency sensor 27. The control I / F44 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 above control by the CPU 40 reading and executing the program from the flash memory 41, but the above control may be realized by using hardware such as a circuit.

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

If it is determined in step 101 that F is _{smaller than F d} , the process proceeds to step 102, and it is determined whether or not the difference RL between the indoor air conditioning load and the generated cooling capacity is _{smaller than the load threshold value RL th.}

The difference RL between the indoor air conditioning load and the generation capacity can be detected by using the set temperature, the detection value (room temperature) detected by the room temperature sensor 13, and the amount of change in room temperature within a predetermined time. In the predetermined time, if it is a short time such as the time required to control the indoor expansion valve 16 (about several seconds), the amount of change is too small to detect the amount of change, and if it is a long time, intermittent operation is performed during that time. Since there is a possibility that it will enter, it can be set to, for example, several tens of seconds to several minutes.

When it is determined that the RL is RL _th or more, the cooling capacity is relatively small with respect to the air conditioning load and it is not necessary to reduce the capacity, so that the opening degree of the indoor expansion valve 16 is not controlled. Therefore, the process returns to step 101 and the control is continued.

On the other hand, when it is determined in step 102 that the RL is _{smaller than the RL th} , the cooling capacity is relatively large with respect to the air conditioning load, so the process proceeds to step 103 and the indoor expansion valve 16 is opened in order to reduce the flow rate of the refrigerant. Reduce the degree. When the opening degree of the indoor expansion valve 16 is reduced, the flow rate of the refrigerant is reduced, and since the pressure is low, the two-phase refrigerant becomes a gas phase with a smaller amount of heat exchange, and thus functions as an evaporator of the heat exchanger 11. The area (effective area) of the heat transfer tube is also reduced. Since the air in the room is cooled mainly by the latent heat when the refrigerant evaporates, the cooling capacity can be reduced by reducing the effective area. By reducing the cooling capacity, all the refrigerant can be evaporated, and the degree of superheat can be imparted and discharged from the heat exchanger 11.

The control device 26 controls the rotation speed of the compressor 21 based on the set temperature and the detection value of the room temperature sensor 13, and controls the opening degree of the outdoor expansion valve 24 so as to keep the degree of superheat within a certain range. Therefore, when the indoor load is large, the control device 26 increases the rotation speed of the compressor 21 to increase the circulation amount of the refrigerant, and when the indoor load is small, the rotation speed of the compressor 21 is decreased to increase the circulation amount of the refrigerant. Reduce.

Even when the indoor load gradually decreases and the operation of the compressor 21 reaches the minimum operating frequency, the compressor 21 operates at the minimum by reducing the opening degree of the indoor expansion valve 16 to reduce the cooling capacity. Room temperature can be maintained even if the operation is continued at the frequency. Therefore, it is possible to maintain the continuous operation of the compressor 21.

After reducing the opening degree of the indoor expansion valve 16 in step 103, the process returns to step 101 to continue the control. When the operation of the air conditioning system is stopped, this control is also terminated.

FIG. 4 shows the time history of power consumption after the start of operation in the conventional control and the opening control of the indoor expansion valve 16 shown in FIG. The conventional control is a control in which intermittent operation is repeated, and the time history is indicated by a broken line. The conventional control consumes zero power when the thermo is turned off, but consumes a lot of power when the thermo is turned on. On the other hand, when the opening degree control (main control) of the indoor expansion valve 16 is performed, thermo-off / thermo-on does not occur and only a certain low power consumption is consumed. Therefore, the total power consumption surrounded by the time axis and the solid line is consumed. (Value of time integration of power consumption) is smaller than the total power consumption of the conventional control, which is also surrounded by the time axis and the broken line. Therefore, this control can reduce the power consumption as compared with the conventional control.

The control shown in FIG. 3 was only to reduce the opening degree of the indoor expansion valve 16, but when the room temperature rises due to an increase in the outside air temperature and the air conditioning load increases, the reduced cooling capacity is improved. You may want to let it. Further, if the circulation amount of the refrigerant is small and the effective area of the evaporator remains small when the air conditioning load is large, the operation becomes inefficient. Therefore, the control capable of improving the cooling capacity will be described with reference to FIG.

FIG. 5 is a flowchart showing a second example of opening degree control of the indoor expansion valve 16. Starting from step 200, in the same manner as the control shown in FIG. 3, in step 201, it is determined whether or not _{the operating frequency F is smaller than the frequency threshold value F d.} If it is determined that F is _{smaller than F d} , the process proceeds to step 202, and it is determined whether or not the difference RL between the indoor air conditioning load and the generated cooling capacity is _{smaller than the threshold value RL th.} Then, when it is determined that the RL is _{smaller than the RL th} , the process proceeds to step 203, and the opening degree of the indoor expansion valve 16 is reduced in order to reduce the flow rate of the refrigerant. After reducing the opening degree of the indoor expansion valve 16, the process returns to step 201 to continue the control.

If F is _{determined to be F d} or more in step 201, or if RL is _{determined to be RL th} or more in step 202, the process proceeds to step 204 to increase the opening degree 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 circulation amount of the refrigerant is increased and the degree of superheat on the outlet side of the heat exchanger 11 is increased. The opening degree of the indoor expansion valve 16 is increased in order to decrease and increase the effective area. When RL is RL _th or more, it indicates that the air conditioning load is relatively large compared to the generated cooling capacity, and even though the air conditioning load is large, the amount of refrigerant circulating is small and the effective area is also large. If it remains small, the operation will be inefficient. Therefore, the opening degree of the indoor expansion valve 16 is increased to increase the circulation amount of the refrigerant.

After increasing the opening degree of the indoor expansion valve 16, the process returns to step 201 and the control is continued. In this case as well, when the operation of the air conditioning system is stopped, the control is terminated.

The control shown in FIG. 5 was a control for reducing or increasing the opening degree of the indoor expansion valve 16, but if the opening degree is greatly changed at one time, the room temperature will fluctuate. Further, depending on the air conditioning load, the fluctuation of the room temperature may be smaller if the opening degree of the indoor expansion valve 16 is maintained without being changed. This is because the room temperature fluctuates, and if the fluctuation is large, the comfort is impaired. Therefore, the control capable of adjusting and maintaining the opening degree of the indoor expansion valve 16 will be described with reference to FIG.

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

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

_{If it is determined in} step 303 that dT in is _{smaller than dT dec} , the room temperature has dropped sharply and it is necessary to reduce the cooling capacity. Therefore, the process proceeds to step 304, depending on the amount of change in room temperature dT _in . Therefore, the amount of change in the opening degree of the indoor expansion valve 16 is calculated, and the opening degree of the indoor expansion valve 16 is reduced according to the amount of change. Then, the process returns to step 301 to continue the control.

_{DT in} Step _303, when it is determined that _{dT dec} above, the process proceeds to step 305, the temperature difference between the set temperature _{T set} room temperature _{T in} is either preset opening decrease start temperature difference [Delta] T _dec smaller Judge whether or not. 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. Reduce the opening. Then, the process returns to step 301 to continue the control.

On the other hand, when it is determined in step 305 that the temperature difference is ΔT _dec or more, 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 too small and the room temperature rises. May rise. Therefore, the process proceeds to step 306, and the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the process returns to step 301 to continue the control.

If F is _{determined to be F d} or more in step 301, or if RL is _{determined to be RL th} or more in step 302, the process proceeds to step 307, and dT _in is a preset opening increase start change amount dT _inc. Determine if it is greater than. dT _inc is the amount of change in room temperature that serves as a reference for starting an increase in the opening degree of the indoor expansion valve 16. When dT _in is _{larger than dT inc} , it indicates that the room temperature has changed significantly due to an increase in outside air temperature or the like, so it is necessary to increase the opening degree of the indoor expansion valve 16 to increase the flow rate of the refrigerant. Therefore, _{when it is determined that the dT in} is _{larger than the dT inc} , the process proceeds to step 308, and 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 is performed. Increase the opening degree of the valve 16.

_{If dT in} in step 307 is less than or equal to _{dT inc,} the process proceeds to step 309, room _T the temperature difference between the _in and the set temperature _{T set} is greater than a preset opening degree increase start temperature difference [Delta] T _inc not Is determined. ΔT _inc is the temperature difference between the room temperature and the set temperature, which is a reference for starting the increase in the opening degree of the indoor expansion valve 16. When the temperature difference is _{larger than ΔT inc} , it is necessary to increase the opening degree of the indoor expansion valve 16 to increase the flow rate of the refrigerant, so the process proceeds to step 308. On the other hand, _{if the opening degree of the indoor expansion valve 16 is controlled to be increased when the temperature difference is ΔT inc} or less, the cooling capacity may be increased and the room temperature may be lowered even though the room temperature has not risen. Therefore, the process proceeds to step 310, and the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the process returns to step 301 to continue the control.

In this way, the room temperature can be further stabilized by controlling the opening degree of the indoor expansion valve 16 to be adjusted and maintained. In this case as well, when the operation of the air conditioning system is stopped, the control is terminated.

The control shown in FIG. 6 was a control for adjusting and maintaining the opening degree of the indoor expansion valve 16, but by using the detected values of the

pipe temperature sensors

14 and 15, the refrigerant on the outlet side of the indoor heat exchanger Control with the degree of superheat as the target value becomes possible. Therefore, the control using the detected values of the

pipe temperature sensors

14 and 15 will be described with reference to FIG. 7.

FIG. 7 is a flowchart showing a fourth example of 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 or not _{the dT in} is smaller than the superheat degree increase start change amount dT _inc. In the example shown in FIG. 6, dT _inc was the opening change start change amount, but in this example, it is the superheat degree increase start change amount. Similarly, in this example, dT _dec is the amount of change in the start of decrease in superheat, ΔT _inc is the difference in start temperature of increase in superheat, and ΔT _dec is the difference in start temperature of increase in superheat.

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

In step 404, the target degree of superheat on the outlet side of the refrigerant of the heat exchanger 11 is calculated 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 in a predetermined time. In this case, by reducing the flow rate of the refrigerant and imparting a degree of superheat to reduce the effective area, the cooling capacity is lowered, so that the degree of superheat increases.

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 on 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. do. Here, the opening degree of the indoor expansion valve 16 is reduced. Then, the process returns to step 401 to continue the control.

If the temperature difference between _{T in} and _{T set} is less than or equal to [Delta] T _dec at step 406, the process proceeds to step 407, as in step 404, for although calculates the target degree of superheat, not to lower the cooling capacity, heating The degree is maintained at the current degree of superheat, and in step 408, the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the process returns to step 401 to continue the control.

_{If it is determined in} step 409 that dT in is _{larger than dT inc} , the process proceeds to step 410, and the target superheat degree is calculated in the same manner as in step 404. In this case, the degree of superheat is reduced because the cooling capacity is improved by increasing the flow rate of the refrigerant and reducing the degree of superheat to increase the effective area.

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 such that the refrigerant superheat degree on the outlet side of the indoor heat exchanger becomes the target superheat degree obtained in step 410 is calculated to expand the room. The opening degree of the valve 16 is controlled. In this case, the opening degree of the indoor expansion valve 16 is increased. Then, the process returns to step 401 to continue the control.

If the temperature difference between _{T in} and _{T set} is judged to be larger than [Delta] T _inc at step 412, the process proceeds to step 413, as in step 404, for although calculates the target degree of superheat, which does not increase the cooling capacity, The degree of superheat is maintained at the current degree of superheat, and in step 414, the opening degree of the indoor expansion valve 16 is maintained at the current opening degree. Then, the process returns to step 401 to continue the control. In this case as well, when the operation of the air conditioning system is stopped, the control is terminated.

So far, it has been described that the opening degree control of the indoor expansion valve 16 is performed by the control device 26 included in the outdoor unit 20, but the opening degree control of the indoor expansion valve 16 is limited to the control device 26. It is not something that is done. For example, it may be carried out by a control device provided in the indoor unit 10, or may be carried out by a centralized control device 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 composed of one unit each. Therefore, 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 indoor unit 10a to 10c is installed in each room and adjusts the room temperature in each room so as to reach the set temperature. Since each of the indoor units 10a to 10c is provided with indoor expansion valves 16a to 16c, the cooling capacity can be adjusted for each room. Therefore, even if the air conditioning load differs from room to room, the room temperature in each room can be stabilized while avoiding 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 equipment can be improved and failures can occur. Since it is reduced, reliability can be improved. Moreover, since the room temperature can be stabilized, comfort can be maintained.

Although the indoor unit, the air conditioning system, and the control method of the present invention have been described in detail with the above-described embodiments, the present invention is not limited to the above-described embodiments, and other embodiments and additions have been made. , Changes, deletions, etc. can be made within the range that can be conceived by those skilled in the art, and are included in the scope of the present invention as long as the actions and effects of the present invention are exhibited in any of the embodiments.

10, 10a to 10c ...

Indoor units

11, 11a to 11c ...

Heat exchangers

12, 12a to 12c ... Fans 13, 13a to 13c ...

Room temperature sensors

14, 14a to 14c, 15, 15a to 15c ...

Piping temperature sensors

16, 16a ~ 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 sensors

30, 31 ... Piping 40 ... CPU
41 ... Flash memory 42 ... RAM
43 ... Communication I / F
44 ... Control I / F
45 ... Bus

Claims

An air conditioning system that includes an indoor unit and an outdoor unit.
The indoor unit
With a heat exchanger
Indoor temperature detecting means for detecting indoor temperature and
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle,
The outdoor unit
With a heat exchanger
With a compressor,
A frequency detecting means for detecting the operating frequency of the compressor, and
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle.
According to the indoor temperature detected by the indoor temperature detecting means, the amount of change in the indoor temperature over a predetermined time, and the operating frequency detected by the frequency detecting means, the valve of the indoor unit An air conditioning system that includes control means to control the opening.
In the control means, the operating frequency detected by the frequency detecting means is smaller than the frequency threshold value, and the difference between the air conditioning load and the air conditioning capacity is set as the indoor temperature and the set temperature detected by the indoor temperature detecting means. A claim that controls to reduce the opening degree of the valve of the indoor unit when the difference is detected from the difference between the above and the amount of change in the indoor temperature during the predetermined time and the detected difference is smaller than the load threshold value. The air conditioning system according to 1.
In the control means, the operating frequency detected by the frequency detecting means is equal to or higher than the frequency threshold value, or the difference between the air conditioning load and the air conditioning capacity is set to the indoor temperature and the set temperature detected by the indoor temperature detecting means. The difference is detected from the difference between the above and the amount of change in the indoor temperature during the predetermined time, and when the detected difference is equal to or greater than the load threshold value, control is performed to increase the opening degree of the valve of the indoor unit. The air conditioning system according to 1.
The control means calculates the amount of change in the opening degree of the valve of the indoor unit based on the temperature in the room detected by the room temperature detecting means and the amount of change in the temperature in the room in the predetermined time. , The air conditioning system according to any one of claims 1 to 3.
The indoor unit is
Includes two pipe temperature detecting means for detecting the temperature of each of the two pipes connecting the heat exchanger and the outdoor unit.
The control means determines the target degree of superheat of the refrigerant discharged from the heat exchanger based on the temperature in the room detected by the room temperature detecting means and the amount of change in the temperature in the room in the predetermined time. Calculate and calculate the amount of change in the opening degree of the valve of the indoor unit so that the degree of superheat obtained from the difference between the two temperatures detected by the two pipe temperature detecting means becomes the calculated target degree of superheat. The air conditioning system according to claim 4.
An air conditioning system equipped with multiple indoor units and outdoor units.
Each of the indoor units
With a heat exchanger
Indoor temperature detecting means for detecting indoor temperature and
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle,
The outdoor unit
With a heat exchanger
With a compressor,
A frequency detecting means for detecting the operating frequency of the compressor, and
Including a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle.
The temperature of each room detected by the indoor temperature detecting means of each indoor unit, the amount of change in the temperature of each room in a predetermined time, and the frequency detection means of each indoor unit detected. An air conditioning system including a control means for controlling the opening degree of each valve of each indoor unit according to each operating frequency.
The control means detects the indoor temperature of one or more indoor units when the operating frequency detected by the frequency detecting means of the indoor unit is smaller than the frequency threshold value and the difference between the air conditioning load and the air conditioning capacity is detected. The valve of the indoor unit is detected from the difference between the indoor temperature and the set temperature detected by the means and the amount of change in the indoor temperature during the predetermined time, and when the detected difference is smaller than the load threshold value. The air conditioning system according to claim 6, wherein control is performed to reduce the opening degree of the air conditioning system.
For one or more indoor units, the indoor temperature detecting means determines that the operating frequency detected by the frequency detecting means of the indoor unit is equal to or higher than the frequency threshold value, or the difference between the air conditioning load and the air conditioning capacity. When the difference detected from the difference between the indoor temperature and the set temperature detected by the above and the amount of change in the indoor temperature during the predetermined time is equal to or greater than the load threshold value, the valve of the indoor unit is used. The air conditioning system according to claim 6, wherein the air conditioning system is controlled to increase the opening degree of the air conditioning system.
The control means is 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 for one or more indoor units. The air conditioning system according to any one of claims 6 to 8, wherein the amount of change in the opening degree of the valve is calculated.
Each indoor unit is
Includes two pipe temperature detecting means for detecting the temperature of each of the two pipes connecting the heat exchanger and the outdoor unit.
For one or more indoor units, the control means is 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 target superheat degree of the refrigerant discharged from the heat exchanger 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. The air conditioning system according to claim 9, wherein the amount of change in the opening degree of the valve of the indoor unit so as to become superheated is calculated.
An indoor unit including a heat exchanger, an indoor temperature detecting means for detecting the indoor temperature, and a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle.
An outdoor unit including a heat exchanger, a compressor, a frequency detecting means for detecting the operating frequency of the compressor, and a valve for adjusting the flow rate of the refrigerant flowing in the refrigeration cycle.
A control method performed by said control means of an air conditioning system, including control means.
A step of calculating the 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
The valve of the indoor unit is opened according to the indoor temperature detected by the indoor temperature detecting means, the operating frequency detected by the frequency detecting means, and the calculated amount of change in the indoor temperature. A control method, including steps to control the degree.