air conditioning system

Abstract

To appropriately control operation of an indoor unit during stop of heating operation, while preventing abnormal pressure rise in a compressor.SOLUTION: An air conditioning system includes one outdoor unit and a plurality of indoor units, where the outdoor unit includes: a compressor; a pressure sensor that detects a discharge pressure of the compressor; and a control unit that operates an indoor fan of the indoor unit during stop of heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is less than a total number of indoor units in the air conditioning system, and a detection pressure value detected by the pressure sensor is larger than a predetermined first pressure threshold value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an air conditioning system. [Background technology]

[0002] Air conditioning systems in which multiple indoor units are connected in parallel to one outdoor unit are known. In such air conditioning systems, each indoor unit is turned on and off independently. Patent Document 1 discloses a technology for such an air conditioning system in which, if the compressor of the first indoor unit is operating when the operation of the first indoor unit is interrupted, a first control unit operates the indoor fan at a predetermined speed or higher and transmits operating information indicating that the compressor is operating to a second indoor unit via a remote control device. As a result, the indoor fan of the second indoor unit operates at a predetermined speed or higher, along with the first indoor unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-300175 Summary of the Invention [Problem to be solved by the invention]

[0004] In an air conditioning system in which multiple indoor units are connected to one outdoor unit as described above, when there are only a few indoor units operating in heating mode, there are fewer indoor units on the high-pressure side that function as condensers, and the pressure on the high-pressure side is more likely to rise due to the influence of excess refrigerant. This can lead to a compressor protection state, causing an alarm to sound and operation to stop. In response to this, the technology in Patent Document 1 operates the indoor fans of the two indoor units of the air conditioner at a predetermined speed or higher while the compressor is operating, preventing pressure increases in the compressor.

[0005] However, when the number of indoor units in a system is large, and a relatively large number of indoor units are continuing heating operation, an abnormal increase in compressor pressure is not a problem, and there is no need to perform the above-described control. In this way, if an indoor unit that is not in heating operation operates, it may cause discomfort or an unpleasant feeling to the user.

[0006] The present invention has been made in consideration of these problems, and aims to appropriately control the operation of indoor units when heating operation is stopped while preventing an abnormal increase in compressor pressure in an air conditioning system in which multiple indoor units are connected to one outdoor unit, when each indoor unit can independently turn heating operation on and off. [Means for solving the problem]

[0007] The present invention provides an air conditioning system including one outdoor unit and a plurality of indoor units, wherein the outdoor unit comprises a compressor, a pressure sensor that detects the discharge pressure of the compressor, and a control unit that operates an indoor fan of an indoor unit that is not in heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is less than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold. When operating the indoor fan of the indoor unit whose heating operation is stopped, the control unit maintains the louver of the indoor unit in a closed state. Another aspect of the present invention is an air conditioning system including one outdoor unit and multiple indoor units, wherein the outdoor unit comprises a compressor, a pressure sensor that detects the discharge pressure of the compressor, and a control unit that operates an indoor fan of an indoor unit that is not operating in heating mode when the number of indoor units performing heating operation is equal to or less than a reference number that is less than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold, and when the number of indoor units is equal to or less than the reference number and the detected pressure value is greater than the first pressure threshold, the control unit selects an indoor fan that is not operating based on rated capacity information of the indoor unit that is not operating in heating mode, and operates the selected indoor fan. Another aspect of the present invention is an air conditioning system including one outdoor unit and multiple indoor units, wherein the outdoor unit comprises a compressor, a pressure sensor that detects the discharge pressure of the compressor, and a control unit that operates an indoor fan of an indoor unit that is not operating in heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is less than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold, and when the number of indoor units performing the heating operation is equal to or less than the reference number and the detected pressure value is greater than or equal to the first pressure threshold, the control unit selects one of the indoor fans that is not operating based on rated capacity information of the indoor units that are not operating in heating operation, and operates the selected indoor fan. [Effects of the Invention]

[0008] According to the present invention, it is possible to appropriately control the operation of the indoor unit when the heating operation is stopped while preventing an abnormal increase in compressor pressure. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an overall configuration diagram of an air conditioning system. [Figure 2] FIG. 1 is a diagram showing a refrigerant circuit in an air conditioning system. [Figure 3]FIG. 4 is a diagram showing the operating states of a plurality of indoor units. [Figure 4] 10 is a flowchart showing a pressure control process. [Figure 5] 10 is a flowchart showing a pressure control process according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a diagram showing the overall configuration of an air conditioning system 1 according to an embodiment. The air conditioning system 1 includes one outdoor unit 10, multiple indoor units 20, and remote controllers 30 corresponding to each indoor unit 20. The indoor units 20 are installed, for example, in different rooms. Each indoor unit 20 is provided with a louver 25, which opens during air conditioning operation, allowing air that has undergone heat exchange in the indoor unit 20 to flow through the louver 25 into the room. The outdoor unit 10 and each indoor unit 20 are connected to each other via a communication cable so that they can communicate with each other. Each indoor unit 20 is also connected to its corresponding remote controller 30 via a communication cable so that they can communicate with each other. As another example, the outdoor unit 10 and each indoor unit 20 may be configured to communicate wirelessly with each other. The indoor units 20 and the remote controller 30 may also be configured to communicate wirelessly with each other.

[0011] Fig. 2 is a diagram showing a refrigerant circuit Q of the air conditioning system 1 according to the embodiment. Note that the solid arrows shown in Fig. 2 indicate the flow of refrigerant during heating operation, and the dashed arrows shown in Fig. 2 indicate the flow of refrigerant during cooling operation.

[0012] The outdoor unit 10 and each indoor unit 20 are connected in parallel by refrigerant piping. Each indoor unit 20 is equipped with an indoor heat exchanger 21, an indoor fan 22, and an on-off valve 23. In the indoor heat exchanger 21, heat exchange occurs between the refrigerant flowing through its heat transfer tube and the indoor air sent in from the indoor fan 22. The indoor heat exchanger 21 operates as a condenser or an evaporator depending on the switching of a four-way valve 16, which will be described later. The indoor fan 22 is installed near the indoor heat exchanger 21. The indoor fan 22 sends indoor air to the indoor heat exchanger 21.

[0013] The outdoor unit 10 includes a compressor 11, an accumulator 12, an outdoor heat exchanger 13, an outdoor fan 14, an expansion valve 15, and a four-way valve 16. The expansion valve 15 has the function of decompressing the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 13 and the indoor heat exchanger 21). The refrigerant decompressed in the expansion valve 15 is guided to the "evaporator" (the other of the outdoor heat exchanger 13 and the indoor heat exchanger 21).

[0014] In the outdoor heat exchanger 13, heat is exchanged between the refrigerant flowing through its heat transfer tubes and the outside air sent in by the outdoor fan 14. The outdoor heat exchanger 13 operates as a condenser or an evaporator by switching a four-way valve 16. The outdoor fan 14 is installed near the outdoor heat exchanger 13 and sends outside air to the outdoor heat exchanger 13. The four-way valve 16 is a valve that switches the refrigerant flow path depending on the operation mode of the air conditioning system 1. The accumulator 12 separates the refrigerant into gas and liquid. The gas refrigerant discharged from the accumulator 12 flows into the compressor 11. The compressor 11 compresses the low-temperature, low-pressure gas refrigerant and discharges it as high-temperature, high-pressure gas refrigerant.

[0015] Each indoor unit 20 is equipped with a communication unit 24. The communication unit 24 communicates with a corresponding remote controller 30. The outdoor unit 10 is equipped with a communication unit 17 and a control unit 18. The communication unit 17 communicates with each of the multiple remote controllers 30. The control unit 18 is equipped with a CPU and memory, and controls each part of the air conditioning system 1. The pressure sensor 19 is installed in the piping on the discharge side of the compressor 11, and detects the discharge pressure.

[0016] In the air conditioning system 1 of this embodiment, for example, assume that ten indoor units are provided, and as shown in FIG. 3, only one of the ten indoor units is in heating operation, while the remaining nine units have stopped heating operation. In this case, heat exchange occurs in the one indoor unit 20 in heating operation, but the flow of refrigerant stops in the remaining nine indoor units 20, and gas refrigerant remains. The amount of refrigerant remaining in each indoor unit 20 is small, resulting in excess refrigerant and an increase in pressure on the high-pressure side of the refrigerant circuit Q. When the pressure increases in this way, the compressor enters a compressor protection state, and the compressor 11 may stop.

[0017] In contrast to this, in the air conditioning system 1 of this embodiment, the control unit 18 performs pressure control processing shown in Fig. 4 to prevent a pressure increase on the high-pressure side. Fig. 4 is a flowchart showing the pressure control processing.

[0018] When the control unit 18 receives an operation signal to start heating operation from any of the remote controllers 30, it starts the heating operation (step S100). Next, the control unit 18 identifies the number of indoor units 20 that are continuing the heating operation based on the operation signals received from each remote controller 30, and compares this number with a reference number (step S102). Specifically, the control unit 18 identifies the number of indoor units 20 that received the operation signal to start heating operation as the number of indoor units 20 that are continuing the heating operation. The reference number is a predetermined number that is smaller than the total number of indoor units provided in the air conditioning system 1. If the number of indoor units 20 that are continuing the heating operation is more than the reference number (NO in step S102), the control unit 18 compares the numbers again after a certain period of time has elapsed (step S102). In this way, if the number of indoor units that are continuing the heating operation is more than the reference number, an abnormal increase in high-pressure side pressure is not a problem, and the control unit 18 continues to periodically monitor the number of indoor units.

[0019] If the number of indoor units 20 continuing the heating operation is equal to or less than the reference number (YES in step S102), the control unit 18 acquires the detected pressure value (Pd) detected by the pressure sensor 19 and compares the detected pressure value (Pd) with a first pressure threshold (Pdh) (step S104). Here, the first pressure threshold (Pdh) is a predetermined value that is smaller than the pressure at which the compressor 11 enters the protection state. If the detected pressure value (Pd) is equal to or less than the first pressure threshold (NO in step S104), the control unit 18 compares the detected pressure value (Pd) with the first pressure threshold (Pdh) again after a certain time has elapsed (step S104).

[0020] If the detected pressure value (Pd) is greater than the first pressure threshold (Pdh) (YES in step S104), the control unit 18 controls the indoor fan 22 of the indoor unit 20 that is not in heating operation to start operating at low speed (step S106). Here, low speed means a speed that is slower than the speed (number of rotations) of the indoor fan 22 of the indoor unit 20 that is in heating operation. Note that the number of rotations in this case is assumed to be set in advance. Furthermore, when the indoor fan 22 is rotating at low speed, the control unit 18 keeps the louvers 25 closed for the indoor unit 20 that has the indoor fan 22 operating at low speed.

[0021] In this way, by operating the indoor fan 22 of the indoor unit 20 at a low speed when the heating operation is stopped, it is possible to prevent an abnormal increase in pressure on the high-pressure side of the refrigerant circuit Q. Furthermore, for the indoor unit 20 when the heating operation is stopped, the control unit 18 controls the indoor fan 22 to operate at a low speed and to close the louver 25. In this way, by minimizing the operation of the indoor unit 20 that is set to stop heating operation and minimizing the flow of air into the room, it is possible to prevent the user from feeling uncomfortable or uneasy.

[0022] Next, the control unit 18 compares the detected pressure value (Pd) with a second pressure threshold (Pdl) (step S108). Here, the second pressure threshold (Pdl) is a predetermined value that is smaller than the first pressure threshold (Pdh). As another example, the second pressure threshold (Pdl) may be equal to the first pressure threshold (pdh). If the detected pressure value (Pd) is greater than the second pressure threshold (Pdl) (NO in step S108), the control unit 18 compares the detected pressure value (Pd) with the second pressure threshold (Pdl) again after a certain time has elapsed (step S108). On the other hand, if the detected pressure value (Pd) is equal to or less than the second pressure threshold (Pdl) (YES in step S108), the control unit 18 stops the operation of the indoor fan 22 of the indoor unit 20 whose heating operation is stopped, i.e., the indoor fan 22 that is operating at a low speed (step S110).

[0023] In this way, when the detected pressure value becomes equal to or lower than the second pressure threshold, the operation of the indoor fan 22 of the indoor unit 20 during which heating operation is stopped is stopped, thereby preventing unnecessary consumption of electricity and preventing the user from feeling uncomfortable or uneasy.

[0024] As described above, the air conditioning system 1 of this embodiment operates the indoor fan 22 of the indoor unit 20 whose heating operation is stopped when the number of indoor units in heating operation is equal to or less than the reference number and the detected pressure value is less than the first pressure threshold. This makes it possible to prevent an abnormal increase in pressure in the compressor 11.

[0025] Furthermore, when only one indoor fan 22 is installed in an indoor unit 20 whose heating operation is stopped, the pressure in the compressor 11 may not rise to a problematic level. In such cases, there is no need to operate the indoor fan 22 of the indoor unit 20 whose heating operation is stopped. Therefore, in this embodiment, the control unit 18 operates the indoor fan 22 of the indoor unit 20 whose heating operation is stopped when the following conditions are met: the number of indoor units in heating operation is equal to or less than a reference number, and the detected pressure value is less than the first pressure threshold. In this manner, the control unit 18 of this embodiment can appropriately control the operation of the indoor fan 22 of the indoor unit 20 whose operation is stopped. This eliminates the need to operate the indoor fan 22 of the indoor unit 20 whose operation is stopped excessively, thereby reducing energy consumption. Furthermore, it is possible to minimize the discomfort or strangeness felt by the user by operating the indoor fan 22 of the indoor unit 20 whose heating operation is supposed to be stopped.

[0026] It should be noted that the present invention is not limited to the specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims, such as applying a modified version of one embodiment to another modified version.

[0027] In the first modified example, in step S106, the control unit 18 operates the indoor fan 22 of the indoor unit 20 when the heating operation is stopped at a low speed, but the speed of the indoor fan 22 is not limited to that in the embodiment. As another example, the control unit 18 may operate the indoor fan 22 of the indoor unit 20 when the heating operation is stopped at a speed similar to that of the indoor fan 22 of the indoor unit 20 when the heating operation is stopped.

[0028] As a second modified example, in step S106, the control unit 18 may open the louvers 25 of the indoor unit 20 whose heating operation is stopped.

[0029] A third modified example will now be described. In this embodiment, in step S102, the control unit 18 periodically compares the number of indoor units in heating operation with a reference number. However, instead of this, the control unit 18 may wait until it receives an operation signal to stop heating operation from any of the remote controllers 30, and when it receives an operation signal to stop heating operation, it may perform the comparison of the numbers in step S102. This makes it possible to minimize the frequency with which the comparison of the numbers is performed.

[0030] As a fourth modified example, in step S106, the control unit 18 only needs to operate the indoor fans 22 of at least some of the indoor units 20 for which heating operation is stopped, and does not need to operate all of the indoor fans 22. In this case, the control unit 18 may decide which indoor fans 22 to operate based on rated capacity information indicating the rated capacity of each indoor unit 20 provided in the air conditioning system 1. More specifically, the control unit 18 may operate the indoor fans 22 of a predetermined number of indoor units 20 in descending order of rated capacity. Here, it is assumed that the rated capacity information is stored in a memory provided in the control unit 18.

[0031] Furthermore, the control unit 18 may increase the number of indoor fans 22 operated at low speed by one, in accordance with the detected pressure value. Figure 5 is a flowchart showing the pressure control process in this case. Of the processes included in the pressure control process shown in Figure 5, the same processes as those explained with reference to Figure 4 are given the same reference numerals, and explanations thereof will be omitted. In this example, if the detected pressure value (Pd) is greater than the first pressure threshold (Pdl) (YES in step S104), the control unit 18 selects the indoor unit 20 with the greatest rated capacity from among the indoor units 20 whose heating operation is stopped, based on the rated capacity information (step S200).

[0032] Next, the control unit 18 controls the indoor fan 22 of the indoor unit 20 selected in step S200 to start operating at a low speed (step S202). At this time, the control unit 18 also keeps the louver 25 of the selected indoor unit 20 closed. The control unit 18 then proceeds to step S108 and compares the detected pressure value (Pd) with the second pressure threshold (Pdl) (step S108). If the detected pressure (Pd) is greater than the second pressure threshold (Pdl) in step S108 (NO in step S108), the control unit 18 further selects the indoor unit 20 with the highest rated capacity among the indoor units 20 whose indoor fans 22 are not operating (step S204). The control unit 18 then proceeds to step S202 and controls the indoor fan 22 of the indoor unit 20 selected in step S204 to start operating at a low speed. Then, when the detected pressure value (Pd) becomes equal to or less than the second pressure threshold value (Pdl) (YES in step S108), the control unit 18 stops the operation of the indoor fan 22 that is operating at low speed (step S110).

[0033] In this way, the control unit 18 sequentially increases the number of indoor fans 22 that are operated at low speed, thereby preventing unnecessary power consumption. Furthermore, the control unit 18 selects the indoor fans 22 to operate in descending order of rated capacity, thereby minimizing the operation of indoor units 20 for which the user does not want heating operation.

[0034] As another example, the memory may store a priority of each indoor unit included in the air conditioning system 1 based on, for example, rated capacity. When the detected pressure value (Pd) is greater than the first pressure threshold (Pdl), the control unit 18 may select one indoor fan 22 of the indoor unit 20 with the highest priority from among the indoor fans 22 of the indoor units 20 whose heating operation is stopped, operate the selected indoor fan 22, and thereafter operate the remaining indoor fans 22 sequentially in order of priority. The priority may be determined arbitrarily and may, for example, be set by an administrator or the like according to the frequency of use or purpose of use of the space in which each indoor unit is installed. [Explanation of symbols]

[0035] 1. Air conditioning system 10 Outdoor unit 11 Compressor 12 Accumulator 13 Outdoor heat exchanger 14 Outdoor fan 15 Expansion valve 16 Four-way valve 17 Communications Department 18 Control Unit 19 Pressure Sensor 20 Indoor unit 21 Indoor heat exchanger 22 Indoor fan 23 On-off valve 24 Communications Department 25 Louvers 30 Remote Controller

Claims

1. An air conditioning system including one outdoor unit and multiple indoor units, The outdoor unit is A compressor; a pressure sensor that detects the discharge pressure of the compressor; a control unit that operates the indoor fans of the indoor units that are not in heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is smaller than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold value; Equipped with The air conditioning system, wherein the control unit maintains a louver of the indoor unit in a closed state when operating the indoor fan of the indoor unit while heating operation is stopped.

2. An air conditioning system including one outdoor unit and multiple indoor units, The outdoor unit is A compressor; a pressure sensor that detects the discharge pressure of the compressor; a control unit that operates the indoor fans of the indoor units that are not in heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is smaller than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold value; Equipped with The control unit When the number of the indoor units is equal to or less than the reference number and the detected pressure value is equal to or greater than the first pressure threshold, the indoor fan that is not operating is selected based on rated capacity information of the indoor unit that is not operating in heating mode; An air conditioning system that operates selected indoor fans.

3. An air conditioning system including one outdoor unit and multiple indoor units, The outdoor unit is A compressor; a pressure sensor that detects the discharge pressure of the compressor; a control unit that operates the indoor fans of the indoor units that are not in heating operation when the number of indoor units performing heating operation is equal to or less than a reference number that is smaller than the total number of indoor units provided in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold value; Equipped with The control unit When the number of the indoor units performing the heating operation is equal to or less than the reference number and the detected pressure value is equal to or greater than the first pressure threshold, selecting one of the indoor fans that is not operating based on rated capacity information of the indoor units that are not performing the heating operation; An air conditioning system that operates selected indoor fans.

4. 4. The air conditioning system according to claim 1, wherein the control unit operates the indoor fan of the indoor unit whose heating operation is stopped until the detected pressure value becomes equal to or less than a second pressure threshold value that is lower than the first pressure threshold value.

5. The air conditioning system according to claim 1 , wherein the control unit operates the indoor fan of the indoor unit that is not in heating operation at a slower speed than the indoor fan of the indoor unit that is in heating operation.

6. The control unit When the detected pressure value is greater than a predetermined second pressure threshold value while the selected indoor fan is operating, further select one of the indoor fans that is not operating based on the rated capacity information; The air conditioning system according to claim 3 , further comprising operating a selected indoor fan.

7. The control unit When the number of the indoor units performing the heating operation is equal to or less than the reference number and the detected pressure value is equal to or greater than the first pressure threshold, selecting one of the indoor fans that is not operating based on the priority of the indoor units that are not performing the heating operation; The air conditioning system according to claim 1 , wherein selected indoor fans are operated.

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