US20060123810A1

US20060123810A1 - Method for operating air conditioner

Info

Publication number: US20060123810A1
Application number: US11/299,679
Authority: US
Inventors: Do Ha; Sung Choi; Ki Kwon; Won Kang; Baik Chung
Original assignee: LG Electronics Inc
Current assignee: Sansegal Global Ltd; LG Electronics Inc
Priority date: 2004-12-14
Filing date: 2005-12-13
Publication date: 2006-06-15
Also published as: DE602005011094D1; KR100640856B1; EP1684030A3; EP1684030B1; KR20060066838A; EP1684030A2; CN1789845A

Abstract

Disclosed herein is a method for operating an air conditioner which is capable of achieving the effective operation of a plurality of indoor units. The method comprises the steps of: a) receiving operating state information of the indoor units connected to one outdoor unit; b) determining whether or not the amount of refrigerant to be distributed into the indoor units needs to be regulated, based on the operating state information of the indoor units; and c) regulating the amount of the refrigerant to be distributed into the indoor units.

Description

This application claims the benefit of the Korean Patent Application No. 10-2004-105329, filed on Dec. 14, 2004 which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a method for operating an air conditioner, and more particularly, to a method for operating an air conditioner which is capable of achieving the effective operation of a plurality of indoor units.
2. Discussion of the Related Art
Recently, an air conditioner of a type wherein a plurality of indoor units are connected to one outdoor unit has been used in high buildings or other buildings having a plurality of rooms. This type of air conditioner is conventionally referred to as a multi-unit air conditioner. The multi-unit air conditioner uses a plurality of indoor units, which are mounted in a plurality of rooms, respectively, to serve as coolers or heaters, while using one outdoor unit in common.
The outdoor unit includes a compressor to compress a refrigerant to a high-pressure state, a 4-way valve to switch the flow path of the refrigerant, discharged from the compressor, in accordance with the operation mode, that is, cooling mode or heating mode, of each of the indoor units, and an outdoor heat exchanger to perform heat exchange between the refrigerant, introduced into the outdoor heat exchanger, and outdoor air.
Additionally, a plurality of expansion valves for expanding the refrigerant heat-exchanged in the outdoor heat exchanger are provided on conduits connected to the indoor units, respectively. Here, the number of the expansion valves is identical to that of the indoor units.
Each of the indoor units for cooling or heating the associated room includes an indoor heat exchanger to perform heat exchange between indoor air and the refrigerant, and an indoor fan to forcibly circulate the indoor air into the indoor heat exchanger, in order to improve the heat-exchange efficiency of the indoor heat exchanger. While passing through the indoor heat exchanger, the refrigerant, circulating through the indoor units and the outdoor unit, is heat exchanged with the indoor air.
To operate the air conditioner as stated above, the indoor units are provided with indoor unit controllers, respectively, and the outdoor unit is provided with an outdoor unit controller that communicates with the respective indoor unit controllers.
When an operation key of an operating panel installed in each of the indoor units is pressed, the corresponding indoor unit controller receives an operation signal, and performs a control operation for an indoor fan driver, a blowing direction regulator, an indoor temperature sensor, an indoor conduit temperature sensor, and the like required in the indoor unit in accordance with the operation signal. The indoor unit controller also outputs a control signal to the outdoor unit controller, so as to enable the outdoor unit controller to perform a control operation for the compressor, the 4-way valve, and the expansion valve in accordance with the control signal.
In the conventional air conditioner having the above-described configuration, each of the indoor units and the outdoor unit sends and receives operating information in a one to one ratio. In this case, however, there may be a problem in that the operating state of the indoor units is not considered with regard to the whole indoor units when the operation of the air conditioner is controlled. As a result, the indoor units exhibit uneven operating performance.
That is, when different models of indoor units having the same capacity as each other are used, their indoor heat exchangers may exhibit different capabilities from each other. Also, even if the indoor units are of the same model, the indoor units may have a deviation in operating performance in accordance with various installation conditions thereof (for example, the lengths, installation heights, branched shapes, or curvatures of conduits connected to the outdoor unit).
As a result, the indoor units of the conventional air conditioner fail to perform an effective operation.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for operating an air conditioner that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method for operating an air conditioner which is capable of achieving the effective operation of a plurality of indoor units.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for operating an air conditioner comprises the steps of: a) receiving operating state information of a plurality of indoor units connected to one outdoor unit; b) determining whether or not the amount of refrigerant to be distributed into the indoor units needs to be regulated, based on the operating state information of the indoor units; and c) regulating the amount of the refrigerant to be distributed into the indoor units.
Here, the operating state information may include at least one of the temperature of air discharged from each of the indoor units, the temperature of each of indoor unit conduits, the temperature of air suctioned into each of the indoor units, and a flow rate value of each of the indoor units.
Preferably, the method may further comprise the step of: confirming that a controller receives the operating state information from all the indoor units.
The step b) may comprise the sub steps of: b1) calculating the operating performance of each of the indoor units based on the operating state information; and b2) determining whether or not the amount of the refrigerant to be distributed needs to be regulated, in accordance with the operating performance of each of the indoor units.
The operating performance may be calculated by the proportion of an actual operating capability in relation to a rated operating capability under a preset operation condition.
The rated operating capability may be a preset temperature of each of the indoor units, and the actual operating capability may be the temperature of air discharged from each of the indoor units under the preset operation condition.
Preferably, the amount of the refrigerant to be distributed may be regulated when it is determined that there are at least one indoor unit having the operating performance below 1 and at least one indoor unit having the operating performance more than 1.
The amount of the refrigerant to be distributed may be regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units having the operating performance below 1.
The step b1) may comprise the step of: comparing the temperature of air discharged from each of the indoor units with the average temperature of air discharged from all the indoor units, to calculate the operating performance.
Preferably, the amount of the refrigerant to be distributed may be regulated when it is determined that there are at least one indoor unit in which the temperature of air discharged therefrom is higher than the average temperature and at least one indoor unit in which the temperature of air discharged therefrom is lower than the average temperature.
Preferably, when the indoor units operate in heating mode, the amount of the refrigerant to be distributed may be regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of air discharged therefrom is lower than the average temperature of air discharged from all the indoor units.
When the indoor units operate in cooling mode, the amount of the refrigerant to be distributed may be regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of air discharged therefrom is higher than the average temperature of air discharged from all the indoor units.
The step b1) may comprise the step of: comparing the temperature of each of indoor unit conduits with the average temperature of all the indoor unit conduits, to calculate the operating performance.
The amount of the refrigerant to be distributed may be regulated when it is determined that there are at least one indoor unit in which the temperature of the associated conduit is higher than the average temperature and at least one indoor unit in which the temperature of the associated conduit is lower than the average temperature.
When the indoor units operate in heating mode, the amount of the refrigerant to be distributed may be regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of the associated conduit is lower than the average temperature of all the indoor unit conduits.
When the indoor units operate in cooling mode, the amount of the refrigerant to be distributed may be regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of the associated conduit is higher than the average temperature.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
FIG. 1 is a configuration diagram schematically showing an example of an air conditioner which is operable in accordance with an air conditioner operating method of the present invention;
FIG. 2 is a flow chart illustrating a method for operating an air conditioner in accordance with a first embodiment of the present invention;
FIGS. 3A and 3B are flow charts illustrating a method for operating an air conditioner in accordance with a second embodiment of the present invention; and
FIGS. 4A and 4B are flow charts illustrating a method for operating an air conditioner in accordance with a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
First, an example of an air conditioner, which is operable in accordance with an air conditioner operating method of the present invention, will be explained in brief with reference to FIG. 1.
As shown in FIG. 1, the air conditioner is a multi-unit air conditioner, and includes a plurality of indoor units 10, 20, and 30, and one outdoor unit 40.
For the sake of the convenience of explanation, the following description defines three indoor units. However, it should be understood that the number of the indoor units is not essentially limited thereto.
The outdoor unit 40 includes a compressor 41 to compress a refrigerant to a high-temperature and high-pressure state, a 4-way valve 42 to switch the flow path of the refrigerant, discharged from the compressor 41, in accordance with operation mode (for example, cooling mode or heating mode), and an outdoor heat exchanger 43 to perform heat exchange between the circulating refrigerant and outdoor air.
An outdoor fan 44 is arranged at one side of the outdoor heat exchanger 43. The outdoor fan 44 sucks outdoor air, and forcibly blows the sucked air toward the outdoor heat exchanger 43, in order to enable the outdoor air heat exchanger 43 to perform effective heat exchange.
A main electronic expansion valve 45 is provided at a main conduit connected to the outdoor heat exchanger 43. The main electronic expansion valve 45 controls the temperature of the refrigerant discharged from the outdoor heat exchanger 43 to regulate the over-heating degree or over-cooling degree of the refrigerant in accordance with the operation mode of the indoor units.
A plurality of sub electronic expansion valves 11, 21, and 31 are provided at branched-conduits, which are branched from the main conduit to be connected to the indoor units 10, 20, and 30, respectively.
Each of the sub electronic expansion valves 11, 21, and 31 is operated under control of a controller (not shown), in order to enable the associated indoor unit 10, 20 or 30 to selectively perform an air conditioning operation for the associated room in accordance with the operation condition of the associated indoor unit 10, 20 or 30. That is, each of the sub electronic expansion valves 11, 21, and 31 regulates the amount of the refrigerant to be distributed into the associated indoor unit 10, 20, or 30, and selectively cuts off the refrigerant supplied to the associated indoor unit 10, 20, or 30. In particular, the sub electronic expansion valves 11, 21, and 31 expand the circulating refrigerant to an easily evaporable low-temperature and low-pressure state.
The indoor units 10, 20, and 30 include respective indoor heat exchangers 12, 22, and 32 for heating or cooling indoor air, and respective indoor fans 13, 23, and 33 for forcibly circulating the indoor air into the indoor heat exchangers 12, 22, and 32 to enable the indoor heat exchangers 12, 22, and 32 to effectively perform heat exchange.
When the indoor units 10, 20, and 30 operate in cooling mode in the air conditioner having the above-described configuration, the 4-way valve 42 is in an Off state. Accordingly, the refrigerant flows along the path as indicated by solid-line arrows in FIG. 1.
Conversely, when the indoor units 10, 20, and 30 operate in heating mode, the 4-way valve 42 is in an ON state. In this case, accordingly, the refrigerant flows along the path as indicated by dotted-line arrows in FIG. 1.
Meanwhile, in the air conditioner as stated above, indoor unit controllers (not shown) are mounted in the indoor units 10, 20, and 30, respectively, to receive operating state information of all the indoor units 10, 20, and 30 and to output the information to an outdoor unit controller (not shown) mounted in the outdoor unit 40. The outdoor unit controller receives and generalizes the operating state information outputted from the indoor unit controllers, to perform a control operation for the air conditioner.
Now, a method for operating the air conditioner in accordance with several embodiments of the present invention will be explained with reference to FIGS. 2, 3A and 3B, and 4A and 4B.
First, a method for operating the air conditioner in accordance with a first embodiment of the present invention will be explained with reference to FIG. 2.
The method for operating the air conditioner comprises the steps of: (S10) receiving operating state information of the indoor units 10, 20, and 30 connected to the outdoor unit 40; (S20) determining whether or not the amount of the refrigerant to be distributed into the indoor units 10, 20, and 30 needs to be regulated, based on the operating state information of the indoor units 10, 20, and 30; and (S30) regulating the amount of the refrigerant to be distributed into the indoor units 10, 20, and 30.
Preferably, the operating state information, to be received in the step S10, may include at least one of the temperature T_dof air discharged from each of the indoor units 10, 20, and 30, the temperature T_pof each of indoor unit conduits, the temperature T_sof air suctioned into each of the indoor units 10, 20, and 30, and the flow rate value of air of each of the indoor units 10, 20, and 30.
More specifically, each of the indoor unit controllers receives the above-described operating state information of the associated indoor unit 10, 20, or 30. The indoor unit also outputs the operating state information to the outdoor unit controller. The outdoor unit controller receives the operating state information of all the indoor unit controllers outputted from the indoor unit controllers, to generalize the information.
In addition to the above-described procedure, preferably, the method for operating the air conditioner in accordance with the present invention further comprises the step of: (S11) confirming that the outdoor unit controller receives the operating state information from all the indoor units.
It is important for the safety of operation to confirm that the operating state information of all the indoor units 10, 20, and 30 connected to the outdoor unit 40 is wholly transmitted to the outdoor unit controller.
This has the purpose of preventing the generation of errors when the operation of the air conditioner is controlled.
Preferably, the determination step S20 comprises the sub steps of: (S21) calculating the operating performances of the indoor units based on the operating state information; and (S22) determining whether or not the amount of the refrigerant to be distributed needs to be regulated in accordance with the operating performances of the indoor units.
The operating performance may be calculated by the proportion of an actual operating capability of each of the indoor units in relation to a rated operating capability of the corresponding indoor unit under a preset operation condition.
For example, when a preset temperature of each of the indoor units, inputted by a user, is given as the rated operating capability, and the temperature T_dof air discharged from each of the indoor units under the preset operation condition is given as the actual operating capability, the operating performance of each of the indoor units can be calculated.
More specifically, the operating performance can be calculated by dividing the actual temperature T_dof air discharged from each of the indoor units by the preset temperature of the corresponding indoor unit under the preset operation condition.
Of course, the operating performance may be calculated in the same manner by the use of the temperature T_sof air to be suctioned, or the temperature T_pof the associated indoor unit conduit.
Here, the temperature T_sof air to be suctioned corresponds to the temperature of indoor air of each of rooms to be suctioned into the associated indoor unit. Thus, when the temperature T_sof air to be suctioned is given as the actual operating capability, and a preset temperature of each of the rooms, inputted by the user, is given as the rated operating capability under a preset operation condition, the operating performance can be calculated by dividing the temperature T_sof air to be suctioned by the preset temperature of the associated room.
Based on the above description, it can be understood that the operating performance can be calculated in consideration of the whole operating state information as stated above.
The operating performance of each of the indoor units calculated in the above-described various manners is classified into one having a value more than 1 and the other one having a value below 1.
When a certain indoor unit has the operating performance below 1, it is preferable that the amount of the refrigerant to be distributed be regulated to increase the inflow of refrigerant into the indoor unit.
Conversely, when a certain indoor unit has the operating performance more than 1, it is preferable that the amount of the refrigerant to be distributed be regulated to decrease the inflow of refrigerant into the indoor unit.
More preferably, when it is determined that there are at least one indoor unit having the operating performance below 1 and at least one indoor unit having the operating performance more than 1, the outdoor unit controller outputs a command to regulate the amount of the refrigerant to be distributed.
The regulation step S30 for regulating the amount of the refrigerant to be distributed can be carried out by regulating the sub electronic expansion valves 11, 21, and 31 provided at the respective branched conduits connected to the indoor units, respectively.
Now, a method for operating the air conditioner in accordance with a second embodiment of the present invention will be explained with reference to FIGS. 3A and 3B.
FIG. 3A illustrates a method for operating the air conditioner when the indoor units 10, 20, and 30 operate in cooling mode, and FIG. 3B illustrates a method for operating the air conditioner when the indoor units 10, 20, and 30 operate in heating mode.
The method for operating the air conditioner in accordance with the present embodiment comprises the steps of: (S100) receiving operating state information of the indoor units 10, 20, and 30 connected to the outdoor unit 40; (S200) determining whether or not the amount of refrigerant to be distributed into the indoor units 10, 20, and 30 needs to be regulated, based on the operating state information of the indoor units 10, 20, and 30; and (S300) regulating the amount of the refrigerant to be distributed into the indoor units 10, 20, and 30.
Differently from the method for operating the air conditioner in accordance with the first embodiment of the present invention, the operating state information of the indoor units 10, 20, and 30, to be received in the step S100, includes the temperature T_dof air discharged from each of the indoor units. Hereinafter, only a difference between the present embodiment and the above-described first embodiment will be described for avoiding the overlapping of description.
In the present embodiment, the determination step S200 comprises the sub steps of: (S210) comparing the temperature T_dof air discharged from each of the indoor units with the average temperature T_daof air discharged from the indoor units to calculate the operating performances of the indoor units; and (S220) determining whether or not the amount of the refrigerant to be distributed needs to be regulated in accordance with the operating performances of the indoor units.
Specifically, the outdoor unit controller collects the temperatures T_dof air discharged from all the indoor units 10, 20, and 30 to thereby calculate the average temperature T_da. Subsequently, the outdoor unit controller compares the average temperature T_dawith the temperature T_dof air discharged from each of the indoor units, thereby calculating the operating performance of each of the indoor units.
The outdoor unit controller classifies the indoor units into some indoor units in which the temperature T_dof air discharged therefrom is higher than the average temperature T_daand the remainder in which the temperature T_dof air discharged therefrom is lower than the average temperature T_da.
When the indoor units of the air conditioner operate in cooling mode as shown in FIG. 3A, the amount of the refrigerant to be distributed is regulated in the regulation step S300, so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature T_dof air discharged therefrom is higher than the average temperature T_da.
Conversely, when the indoor units of the air conditioner operate in heating mode as shown in FIG. 3B, the amount of the refrigerant to be distributed is regulated in the regulation step S300, so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature T_dof air discharged therefrom is lower than the average temperature T_da.
More preferably, when it is determined that there are at least one indoor unit in which the temperature T_dof air discharged therefrom is higher than the average temperature T_daand at least one indoor unit in which the temperature T_dof air discharged therefrom is lower than the average temperature T_da, the outdoor unit controller outputs a command to regulate the amount of the refrigerant to be distributed.
The regulation step S300 for regulating the amount of the refrigerant to be distributed can be carried out by regulating the sub electronic expansion valves 11, 21, and 31 provided at the respective branched conduits connected to the indoor units, respectively.
Now, a method for operating the air conditioner in accordance with a third embodiment of the present invention will be explained with reference to FIGS. 4A and 4B.
FIG. 4A illustrates a method for operating the air conditioner when the indoor units 10, 20, and 30 operate in cooling mode, and FIG. 4B illustrates a method for operating the air conditioner when the indoor units 10, 20, and 30 operate in heating mode.
The method for operating the air conditioner in accordance with the present embodiment comprises the steps of: (S400) receiving operating state information of the indoor units 10, 20, and 30 connected to the outdoor unit 40; (S500) determining whether or not the amount of refrigerant to be distributed into the indoor units 10, 20, and 30 needs to be regulated, based on the operating state information of the indoor units 10, 20, and 30; and (S600) regulating the amount of the refrigerant to be distributed into the indoor units 10, 20, and 30.
Differently from the methods for operating the air conditioner in accordance with the first and second embodiments of the present invention, the operating state information of the indoor units 10, 20, and 30, to be received in the step S400, includes the temperature T_pof each of the indoor unit conduits. Hereinafter, only a difference between the present embodiment and the above-described first and second embodiments will be described for avoiding the overlapping of description.
In the present embodiment, the determination step S500 comprises the sub steps of: (S510) comparing the temperature T_pof each of the indoor unit conduits with the average temperature T_paof the indoor unit conduits to calculate the operating performances of the indoor units; and (S520) determining whether or not the amount of the refrigerant to be distributed needs to be regulated in accordance with the operating performances of the indoor units.
Specifically, the outdoor unit controller collects the temperatures T_pof the conduits connected to all the indoor units 10, 20, and 30 to thereby calculate the average temperature T_pa. Subsequently, the outdoor unit controller compares the average temperature T_pawith the temperature T_pof each of the indoor unit conduits, thereby calculating the operating performance of each of the indoor units.
The outdoor unit controller classifies the indoor units into some indoor units in which the temperature T_pof the associated conduit is higher than the average temperature T_paand the remainder in which the temperature T_pof the associated conduit is lower than the average temperature T_pa.
When the indoor units of the air conditioner operate in cooling mode as shown in FIG. 4A, the amount of the refrigerant to be distributed is regulated in the regulation step S600, so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature T_pof the associated conduit is higher than the average temperature T_pa.
Conversely, when the indoor units of the air conditioner operate in heating mode as shown in FIG. 4B, the amount of the refrigerant to be distributed is regulated in the regulation step S600, so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature T_pof the associated conduit is lower than the average temperature T_pa.
More preferably, when it is determined that there are at least one indoor unit in which the temperature T_pof the associated conduit is higher than the average temperature T_paand at least one indoor unit in which the temperature T_pof the associated conduit is lower than the average temperature T_pa, the outdoor unit controller outputs a command to regulate the amount of the refrigerant to be distributed.
The regulation step S600 for regulating the amount of the refrigerant to be distributed can be carried out by regulating the sub electronic expansion valves 11, 21, and 31 provided at the respective branched conduits connected to the indoor units, respectively.
Of course, it can be understood that the methods for operating the air conditioner in accordance with the second and third embodiments of the present invention are available under the assumption that all the indoor units have the same temperature condition as each other.
As apparent from the above description, a method for operating an air conditioner according to the present invention has effects as follows.
Firstly, according to the present invention, the amount of refrigerant to be distributed into each of indoor units can be regulated based on operating state information of all the indoor units. This effectively eliminates a deviation of operating capability between the indoor units caused by differences in the design, manufacture, or installation of the air conditioner. As a result, it is possible to achieve not only the effective operation of the indoor units, but also an improvement in the air conditioning efficiency of a room.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method for operating an air conditioner comprising the steps of:

a) receiving operating state information of a plurality of indoor units connected to one outdoor unit;

b) determining whether or not the amount of refrigerant to be distributed into the indoor units needs to be regulated, based on the operating state information of the indoor units; and

c) regulating the amount of the refrigerant to be distributed into the indoor units.

2. The method as set forth in claim 1, wherein the operating state information includes at least one of the temperature of air discharged from each of the indoor units, the temperature of each of indoor unit conduits, the temperature of air suctioned into each of the indoor units, and a flow rate value of each of the indoor units.

3. The method as set forth in claim 1, further comprising the step of:

confirming that a controller receives the operating state information from all the indoor units.

4. The method as set forth in claim 1, wherein the step b) comprises the sub steps of:

b1) calculating the operating performance of each of the indoor units based on the operating state information; and

b2) determining whether or not the amount of the refrigerant to be distributed needs to be regulated, in accordance with the operating performance of each of the indoor units.

5. The method as set forth in claim 4, wherein the operating performance is calculated by the proportion of an actual operating capability in relation to a rated operating capability under a preset operation condition.

6. The method as set forth in claim 5, wherein the rated operating capability is a preset temperature of each of the indoor units, and the actual operating capability is the temperature of air discharged from each of the indoor units under the preset operation condition.

7. The method as set forth in claim 5, wherein the amount of the refrigerant to be distributed is regulated when it is determined that there are at least one indoor unit having the operating performance below 1 and at least one indoor unit having the operating performance more than 1.

8. The method as set forth in claim 5, wherein the amount of the refrigerant to be distributed is regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units having the operating performance below 1.

9. The method as set forth in claim 4, wherein the step b1) comprises the step of:

comparing the temperature of air discharged from each of the indoor units with the average temperature of air discharged from all the indoor units, to calculate the operating performance.

10. The method as set forth in claim 9, wherein the amount of the refrigerant to be distributed is regulated when it is determined that there are at least one indoor unit in which the temperature of air discharged therefrom is higher than the average temperature and at least one indoor unit in which the temperature of air discharged therefrom is lower than the average temperature.

11. The method as set forth in claim 9, wherein, when the indoor units operate in heating mode, the amount of the refrigerant to be distributed is regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of air discharged therefrom is lower than the average temperature of air discharged from all the indoor units.

12. The method as set forth in claim 9, wherein, when the indoor units operate in cooling mode, the amount of the refrigerant to be distributed is regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of air discharged therefrom is higher than the average temperature of air discharged from all the indoor units.

13. The method as set forth in claim 4, wherein the step b1) comprises the step of:

comparing the temperature of each of indoor unit conduits with the average temperature of all the indoor unit conduits, to calculate the operating performance.

14. The method as set forth in claim 13, wherein the amount of the refrigerant to be distributed is regulated when it is determined that there are at least one indoor unit in which the temperature of the associated conduit is higher than the average temperature and at least one indoor unit in which the temperature of the associated conduit is lower than the average temperature.

15. The method as set forth in claim 13, wherein, when the indoor units operate in heating mode, the amount of the refrigerant to be distributed is regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of the associated conduit is lower than the average temperature of all the indoor unit conduits.

16. The method as set forth in claim 13, wherein, when the indoor units operate in cooling mode, the amount of the refrigerant to be distributed is regulated in the step c), so that an increased amount of the refrigerant is introduced into one or ones of the indoor units in which the temperature of the associated conduit is higher than the average temperature.