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] There is known an air conditioning system in which multiple indoor units are connected in parallel to one outdoor unit. In such an air conditioning system, each indoor unit is turned on and off independently. As such an air conditioning system, Patent Document 1 discloses a technique in which a first control unit operates an indoor fan at a predetermined speed or higher when the compressor is operating when the operation of the first indoor unit is interrupted, and transmits operation information that the compressor is operating to the second indoor unit via a remote control device. As a result, the second indoor unit operates its indoor fan at a predetermined speed or higher together 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 few indoor units operating in heating mode, there are few indoor units on the high-pressure side that function as condensers, so the pressure on the high-pressure side is likely to rise due to the influence of excess refrigerant. This may result in a compressor protection state, an alarm being generated, and operation being stopped. In response to this, the technology of Patent Document 1 operates the indoor fans of the two indoor units equipped in the air conditioner at a predetermined speed or higher while the compressor is operating, preventing pressure rise in the compressor.

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

[0006] The present invention has been made in consideration of these problems, and has an object 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 a single outdoor unit, where each indoor unit is capable of turning heating operation on and off independently. [Means for solving the problem]

[0007] The present invention is an air conditioning system including one outdoor unit and multiple indoor units, wherein the outdoor unit is equipped with a compressor, a pressure sensor that detects the discharge pressure of the compressor, and a control unit that operates the indoor fan of an indoor unit that has stopped 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 in the air conditioning system and the detected pressure value detected by the pressure sensor is greater than a predetermined first pressure threshold. Effect 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 description of the drawings]

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

[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, a plurality of indoor units 20, and a remote controller 30 corresponding to each indoor unit 20. Each indoor unit 20 is installed in, for example, a different room. Each indoor unit 20 is provided with a louver 25, and during air conditioning operation, the louver 25 opens, and air that has been heat exchanged in the indoor unit 20 flows into the room through the louver 25. 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. In addition, each indoor unit 20 is connected to a 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 perform wireless communication. The indoor unit 20 and the remote controller 30 may also be configured to perform wireless communication.

[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 the refrigerant during heating operation. The dashed arrows shown in Fig. 2 indicate the flow of the 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 from the indoor fan 22. The indoor heat exchanger 21 operates as a condenser or an evaporator by switching a four-way valve 16 described below. 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 a function of reducing the pressure of the refrigerant condensed in the "condenser" (one of the outdoor heat exchanger 13 and the indoor heat exchanger 21). The refrigerant reduced in pressure 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 exchange takes place between the refrigerant flowing through its heat transfer tube and the outside air sent in from 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 flow path of the refrigerant 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 a 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 only one of them is in heating operation, while the remaining nine units have their heating operation stopped, as shown in Fig. 3. In this case, heat exchange is performed in the one indoor unit 20 in heating operation, but in the remaining nine indoor units 20, the flow of refrigerant stops 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 goes into a protected state, and the compressor 11 may stop.

[0017] In response to this, in the air conditioning system 1 of the present embodiment, in order to prevent a pressure rise on the high pressure side, the control unit 18 performs a pressure control process shown in Fig. 4. Fig. 4 is a flowchart showing the pressure control process.

[0018] When the control unit 18 receives an operation signal to start the 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 continuing the heating operation based on the operation signal 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 the heating operation as the number of indoor units 20 continuing the heating operation. In addition, the reference number is a number that is smaller than the number of all indoor units provided in the air conditioning system 1 and is a predetermined number. If the number of indoor units 20 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 time has elapsed (step S102). In this way, if the number of indoor units continuing the heating operation is more than the reference number, the abnormal increase in the pressure on the high pressure side does not cause a problem, so the control unit 18 continues to periodically monitor the number.

[0019] When 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, and is a value smaller than the pressure at which the compressor 11 is in a protected state. When 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] When the detected pressure value (Pd) is greater than the first pressure threshold value (Pdh) (YES in step S104), the control unit 18 controls the indoor fan 22 of the indoor unit 20 during which the heating operation is stopped to start operating at a low speed (step S106). Here, the low speed is a speed that is slower than the speed (number of rotations) of the indoor fan 22 of the indoor unit 20 during heating operation. Note that the number of rotations in this case is set in advance. Furthermore, when the indoor fan 22 rotates at a low speed, the control unit 18 maintains the louvers 25 closed for the indoor units 20 equipped with the indoor fans 22 operating at a low speed.

[0021] In this way, by operating the indoor fan 22 of the indoor unit 20 at a low speed while 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 while the heating operation is stopped, the control unit 18 controls the indoor fan 22 to operate at a low speed and to close the louvers 25. In this way, by minimizing the operation of the indoor unit 20 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 unnatural.

[0022] Next, the control unit 18 compares the detected pressure value (Pd) with the second pressure threshold (Pdl) (step S108). Here, the second pressure threshold (Pdl) is a value smaller than the first pressure threshold (Pdh) and is a predetermined value. 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 during which the heating operation is stopped, i.e., the indoor fan 22 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 unnatural.

[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] Also, when there is only one indoor fan 22 in the indoor unit 20 during heating operation stop, the pressure of the compressor 11 may not rise to a problematic level, and in such a case, it is not necessary to operate the indoor fan 22 of the indoor unit 20 during heating operation stop. Therefore, in this embodiment, the control unit 18 operates the indoor fan 22 of the indoor unit 20 during heating operation stop when the condition is satisfied that the number of indoor units during heating operation is equal to or less than the reference number and the detected pressure value is less than the first pressure threshold. In this way, the control unit 18 of this embodiment can appropriately control the operation of the indoor fan 22 of the indoor unit 20 during operation stop. As a result, it is not necessary to operate the indoor fan 22 of the indoor unit 20 during operation stop excessively, and energy consumption can be reduced. Also, it is possible to minimize the discomfort and strange feeling caused to the user by the operation of the indoor fan 22 of the indoor unit 20 during heating operation stop.

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

[0027] As such a first modified example, in step S106, the control unit 18 operates the indoor fan 22 of the indoor unit 20 while 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 while the heating operation is stopped at approximately the same speed as the indoor fan 22 of the indoor unit 20 during the heating operation.

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

[0029] A third modified example will 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 compare the numbers in step S102. This makes it possible to minimize the frequency with which the numbers are compared.

[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 determine the 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 one by one according to the detected pressure value. Fig. 5 is a flowchart showing the pressure control process in this case. Among the processes included in the pressure control process shown in Fig. 5, the same processes as those described with reference to Fig. 4 are given the same reference numerals, and the description will be omitted. In this example, when the detected pressure value (Pd) is greater than the first pressure threshold value (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 maintains the louver 25 of the selected indoor unit 20 in a closed state. Then, the control unit 18 proceeds to the process in step S108 and compares the detected pressure value (Pd) with the second pressure threshold value (Pdl) (step S108). In step S108, if the detected pressure (Pd) is greater than the second pressure threshold value (Pdl) (NO in step S108), the control unit 18 further selects the indoor unit 20 with the largest rated capacity among the indoor units 20 whose indoor fans 22 are not operating (step S204). Then, the control unit 18 proceeds to the process in 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 lower 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 operated at low speed, thereby preventing unnecessary consumption of power. Also, the control unit 18 selects the indoor fans 22 to be operated in descending order of rated capacity, thereby minimizing the operation of indoor units 20 for which the user does not wish to perform 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 the rated capacity, etc. Then, 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 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. Also, the priority may be determined arbitrarily, and may be set by an administrator, etc., according to the frequency of use or purpose of use of the space in which each indoor unit is installed, for example. [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 Louver 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 a discharge pressure of the compressor; 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 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; An air conditioning system comprising:

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

3. The air conditioning system according to claim 1 , wherein the control unit operates the indoor fan of the indoor unit when a heating operation is stopped at a slower speed than the indoor fan of the indoor unit when a heating operation is in progress.

4. The air conditioning system according to claim 1 , wherein the control unit, when operating the indoor fan of the indoor unit during which heating operation is stopped, maintains a louver of the indoor unit in a closed state.

5. The control unit is 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 value, select the indoor fan that is not operating based on rated capacity information of the indoor units that are not operating in heating mode; The air conditioning system of claim 1 , further comprising: operating selected indoor fans.

6. The control unit is 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 value, select one of the indoor fans that is not operating based on rated capacity information of the indoor units that are not operating in the heating operation; The air conditioning system of claim 1 , further comprising: operating selected indoor fans.

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

8. The control unit is 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 operating in the heating operation; The air conditioning system of claim 1 , further comprising: operating selected indoor fans.

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