US20140123685A1

US20140123685A1 - Air conditioner and a method of controlling an air conditioner

Info

Publication number: US20140123685A1
Application number: US14/024,682
Authority: US
Inventors: Jeonghun Kim; Jongtae KIM; Jinyoung JOO; Sanghun Lee
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2012-11-02
Filing date: 2013-09-12
Publication date: 2014-05-08
Also published as: CN103807921A; EP2728280A1; KR20140056965A; EP2728280B1

Abstract

An air conditioner and a method of controlling an air conditioner are provided. The air conditioner may include a compressor that compresses a refrigerant and discharges the compressed refrigerant, an outdoor heat exchanger in which outdoor air introduced into an outdoor device and the refrigerant are heat-exchanged with each other, at least one indoor heat exchanger in which indoor air introduced into an indoor device and the refrigerant are heat-exchanged with each other, a plurality of valves respectively disposed in an inflow-side tube and a discharge-side tube of the at least one indoor heat exchanger, and a refrigerant leakage detector that directly or indirectly detects leakage of the refrigerant. When leakage of the refrigerant is detected, the plurality of valves may be blocked or closed in stages.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2012-0123488, filed in Korea on Nov. 2, 2012, which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field
Embodiments disclosed herein provide an air conditioner and a method of controlling an air conditioner.
2. Background
Air conditioners are known. However, they suffer from various disadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein:

FIG. 1 is a schematic diagram of an air conditioner according to an embodiment;

FIG. 2 is a block diagram of the air conditioner of FIG. 1;

FIG. 3 is a flowchart illustrating a method of controlling an air conditioner according to an embodiment;

FIG. 4 is a block diagram of an air conditioner according to another embodiment; and

FIG. 5 is a flowchart illustrating a method of controlling an air conditioner according to another embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. Where possible, like reference numerals have been used to indicate like elements, and repetitive disclosure has been omitted.
In the following detailed description of embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is understood that other embodiments may be utilized and that logical structural, mechanical, electrical, and chemical changes may be made without departing from the spirit or scope. To avoid detail not necessary to enable those skilled in the art to practice the embodiments, the description may omit certain information known to those skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense.
An air conditioner may include a compressor, an outdoor heat exchanger, an indoor heat exchanger, and an expansion valve. A refrigerant is used as a medium to operate the air conditioner. The air conditioner may operate in a heating cycle or cooling cycle according to a flow direction of the refrigerant.
When the air conditioner operates for a long period of time, the refrigerant circulating in the air conditioner may leak from a tube due to installation errors or a user's carelessness. When the refrigerant leaks, heating or cooling performance of the air conditioner may deteriorate, and also, the compressor may be damaged during the operation of the air conditioner. In addition, when a refrigerant which has a bad effect on the human body leaks, a user may have various diseases.
Thus, a refrigerant leakage detector and a method of controlling an air conditioner may be realized. For example, when a temperature difference between a heat exchanger and suctioned air is less than a predetermined value, it may be determined that the refrigerant is leaking. As another example, the leakage of the refrigerant may be directly detected using two electrodes and an impedance measurement device that measures an impedance between the two electrodes.
Also, when the leakage of the refrigerant is detected, an operation of the air conditioner may be stopped to stop circulation of the refrigerant. In related air conditioners, as the operation of the air conditioner may be completely stopped even though it may be determined that there has been a misdetection by the refrigerant leakage detector, use of the air conditioner may be unnecessarily stopped. Also, in a multi-type air conditioner in which a plurality of indoor devices are connected to each other, when a refrigerant leaks in a partial area, an overall operation of all of the indoor devices may be stopped deteriorating convenience in use.
FIG. 1 is a schematic diagram of an air conditioner according to an embodiment. An air conditioner 10 according to this embodiment may include an outdoor device 100, at least one indoor device 200, 300, or 400, and a circulation tube 500 that enables the outdoor device 100 and the indoor device 200, 300, or 400 to communicate with each other.
The outdoor device 100 may include a compressor 110, a flow switching valve 120, an outdoor heat exchanger 130, an outdoor expansion valve 140, and an outdoor device fan 150. Also, the compressor 110, the flow switching valve 120, the outdoor heat exchanger 130, and the outdoor expansion valve 140 may communicate with each other via the circulation tube 500.
The compressor 110 may compress a refrigerant introduced through a suction-side of the circulation tube 500 and discharge the compressed refrigerant into a discharge-side of the circulation tube 500. The flow switching valve 120 may switch a flow direction of the refrigerant flowing in the circulation tube 500 according to an operation mode of the air conditioner 10. The flow switching valve 120 may be a four-way valve.
Air introduced into the outdoor device 100 and the refrigerant passing through the outdoor heat exchanger 130 may be heat-exchanged with each other in the outdoor heat exchanger 130. The outdoor expansion valve 140 may expand the refrigerant passing through the outdoor expansion valve 140. An electrical expansion valve (EEV) may be used as the outdoor expansion valve 140. An open degree of the outdoor expansion valve 140 may be adjustable. When the outdoor expansion valve 140 is fully opened, the circulating refrigerant may pass through the outdoor expansion valve 140 in a state in which the refrigerant is not expanded.
The outdoor fan 150 may guide a flow of outdoor air so that the outdoor air passes through the outdoor heat exchanger 130.
The indoor devices 200, 300, and 400 may include a first indoor device 200, a second indoor device 300, and a third indoor device 400. The first indoor device 200 may include an indoor tube 210, an indoor expansion valve 220, an indoor heat exchanger 230, a refrigerant leakage detector 240, first and second valves 250 and 260 that are respectively disposed in suction and discharge sides of the indoor tube 210, and an indoor device fan 270. The second and third indoor devices may have the same configuration and repetitive disclosure has been omitted.
The indoor tube 210 may communicate with the circulation tube 500 to guide the refrigerant into the indoor device 200. The first valve 250, the indoor expansion valve 220, the indoor heat exchanger 230, and the second valve 260 may be connected to the indoor tube 210.
The indoor expansion valve 220 may expand the refrigerant passing therethrough. An EEV may be used as the indoor expansion valve 220. An open degree of the indoor expansion valve 220 may be adjustable. When the indoor expansion valve 220 is fully opened, the circulating refrigerant may pass through the indoor expansion valve 220 in a state in which the refrigerant is not expanded.
Air introduced into the indoor device 200 and the refrigerant passing through the indoor heat exchanger 230 may be heat-exchanged with each other in the indoor heat exchanger 230.
The refrigerant leakage detector 240 may detect whether a refrigerant within the indoor device 200 is leaking. The refrigerant leakage detector 240 may be disposed on or at a side of the indoor tube 210 or disposed inside or outside of the first indoor device 200. The refrigerant leakage detector 240 may be disposed on or at a tube welding portion at which point or area refrigerant may easily leak. However, embodiments are not limited to the position of the refrigerant leakage detector 240. The refrigerant leakage detector 240 may be spaced apart from the first indoor device 200 and disposed in one position in an indoor space.
The refrigerant leakage detector 240 may directly or indirectly detect leakage of a refrigerant. For example, the refrigerant leakage detector 240 may include two electrodes spaced apart from each other and an impedance measurement device that measures an impedance in a space between the two electrodes. A dielectric constant of air is different from that of a refrigerant. When a refrigerant is introduced between the two electrodes, an impedance value measured by the impedance measurement device may change. Thus, the leakage of the refrigerant may be directly detected by the refrigerant leakage detector 240 by measuring the impedance value.
As another example, the refrigerant leakage detector 240 may include a first temperature sensor that measures a temperature of indoor air introduced into the indoor heat exchanger 230, a second temperature sensor that measures a temperature of the indoor heat exchanger 230, and an arithmetic calculator that calculates a difference between the temperatures measured by the first and second temperature sensors. When a temperature difference value calculated by the arithmetic calculator is less than a predetermined value, it may be determined that a refrigerant is not sufficiently supplied into the indoor heat exchanger 230. In this case, leakage of refrigerant may be probable. Thus, the refrigerant leakage detector 240 may indirectly detect the leakage of the refrigerant by the above-described structure.
However, embodiments are not limited to the refrigerant leakage detector 240 having the above-described structure.
The first and second valves 250 and 260 may selectively block a refrigerant suctioned from the circulation tube 500 into the indoor heat exchanger 230 or discharged from the indoor heat exchanger 230. For example, each of the first and second valves 250 and 260 may be a solenoid valve.
More particularly, the first valve 250 may be disposed in a refrigerant suction-side tube of the indoor heat exchanger 230 in a cooling mode. Also, the second valve 260 may be disposed in a refrigerant discharge-side tube of the indoor heat exchanger 230 in the cooling mode.
Further, the first valve 250 may be omitted. When the first valve 250 is omitted, the outdoor expansion valve 140 or the indoor expansion valve 220 may be closed to block a refrigerant suctioned into or discharged from the indoor heat exchanger 230. In this case, it is unnecessary to provide an additional valve. That is, the existing outdoor expansion valve 140 or the indoor expansion valve 220 may be utilized. The outdoor expansion valve 140 and the indoor expansion valve 220 may be commonly called an expansion valve.
The indoor device fan 270 may guide a flow of indoor air so that the indoor air passes through the indoor heat exchanger 230.
The circulation tube 500 may include a first branch tube 510 and a second branch tube 520. The first and second branch tubes 510 and 520 may be connected to the indoor tube 210 of the first indoor device 200 to guide a refrigerant flowing into the circulation tube 500 so that the refrigerant is introduced into or discharged from the indoor tube 210.
More particularly, the first branch tube 510 may be disposed between the outdoor heat exchanger 130 and the indoor heat exchanger 230. Also, the second branch tube 520 may be disposed between the compressor 110 and the indoor heat exchanger 230.
Although in the exemplary embodiments disclosed herein one indoor heat exchanger is provided in each of the indoor devices 200, 300, and 400, embodiments are not limited thereto. For example, a plurality of indoor heat exchangers may be provided in one indoor device. That is, the first, second, and third indoor devices 200, 300, and 400 may be disposed in the same indoor space to constitute one indoor device.
FIG. 2 is a block diagram of the air conditioner of FIG. 1. Referring to FIG. 2, the air conditioner 10 according to this embodiment may further include an indoor device controller 600, a memory 610, and a timer 620.
The indoor device controller 600 may receive predetermined information from the refrigerant leakage detector 240, the memory 600, and the timer 620 to control operations of the first valve 250, the second valve 260, and the indoor device fan 270.
Also, the indoor controller 600 may determine an operation mode of the air conditioner 10. For example, the indoor device controller 600 may determine whether the air conditioner 10 operates in a cooling mode or a heating mode according to a switching direction of the flow switching valve 120.
Various information related to the operation of the air conditioner 10 may be stored in the memory 610. For example, a first reference time t1 and a second reference time t2, which are criterion of an operation of the first valve 250 or the second valve 260, may be stored in the memory 610.
The timer 620 may measure a leakage time t detected by the refrigerant leakage detector 240.
An abnormality informing device, such as a display or speaker, may be provided to inform a user of leakage of refrigerant.
FIG. 3 is a flowchart illustrating a method of controlling an air conditioner according to an embodiment. Referring to FIG. 3, in an air conditioner according to an embodiment, such as the air conditioner disclosed in FIGS. 1-2, a refrigerant leakage detector, such as refrigerant leakage detector 240 of FIGS. 1-2, may detect leakage of a refrigerant a first time, in step S100. When the leakage of the refrigerant is detected by the refrigerant leakage detector, a leakage detection time t of the refrigerant may be accumulated and measured by a timer, such as timer 620 of FIG. 2. Then, it may be determined whether the leakage detection time t exceeds a first reference time t1 stored in a memory, such as memory 610 of FIG. 1, in step S110.
When the detection time t exceeds the first detection time t1, it is determined whether an operation mode of the air conditioner is a cooling mode, in step S120. When the operation mode of the air conditioner is the cooling mode, a first valve, such as first valve 250 of FIGS. 1-2, may be blocked or turned off, in step S130. As the first valve is blocked or tuned off, a refrigerant introduced into an indoor heat exchanger, such as indoor heat exchanger 230 of FIG. 1, may be blocked.
Also, even when the first valve is blocked or turned off, an indoor device fan, such as indoor device fan 270 of FIG. 2, may continuously operate for a predetermined period of time. As the indoor device fan operates, indoor air introduced into a first indoor device, such as first indoor device 200 of FIG. 1, may be heat-exchanged with the refrigerant previously introduced into the indoor heat exchanger. Thus, in spite of the blocking of the first valve, the indoor air-conditioning may be continuously performed for a predetermined period of time without being stopped.
After the first valve is blocked, whether a refrigerant leaks is detected a second time. More particularly, the timer may accumulate and measure a time t at which the leakage of the refrigerant is detected. Then, it may be determined whether the measured detection time t exceeds the second reference time t2, in step S140.
When the detection time t exceeds the second reference time t2, a second valve, such as second valve 260 of FIGS. 1-2, may be blocked or turned off, in step S150. As the second valve is blocked or turned off, a refrigerant reversely flowing from a circulation tube, such as circulation tube 500 of FIG. 1, into the first indoor device may be blocked.
Then, a user may be informed of the leakage of the refrigerant by an abnormality informing device, such as abnormality informing device 680 of FIG. 1, in step S160. The abnormality informing device may include a display or speaker provided in the air conditioner. The display may inform an abnormal state to a user by a character, a symbol, or a picture. The speaker may inform the abnormal state to the user by sound.
Also, an operation of the first indoor device may be stopped, in step S170. In this case, an operation of the indoor device fan may be also stopped.
In step S120, when the operation mode of the air conditioner is a heating mode, the second valve may be blocked or tuned off, in step S180. Hereinafter, as steps S190 to S200 are similar to steps S140 to S150, repetitive description with respect to steps S190 to S200 has been omitted.
When the leakage of the refrigerant is not detected in step S100, or the detection time t does not exceed the first reference time t1 in step S110, the process returns to step S100 to detect the leakage of the refrigerant. Also, when the detection time t does not exceed the second reference time t2 in step S140, the first valve may be opened or turned on, in step S142. Then, the process may return to step S100 to detect the leakage of the refrigerant.
Also, when the detection time t does not exceed the second reference time t2 in step S190, the second valve may be opened or turned on, in step S192. Then, the process may return to step S100 to detect the leakage of the refrigerant.
FIG. 4 is a block diagram of an air conditioner according to another embodiment. Referring to FIG. 4, an air conditioner according to this embodiment may include a main controller 900, a main memory 910, and a leakage occurrence indoor device number detector 920.
The main controller 900 may receive predetermined information from the main memory 910, a first indoor device controller 600, a second indoor device controller 700, a third indoor device controller 800, and the leakage occurrence indoor device number detector 920 to control operations of a compressor 110 and an outdoor device fan 150.
Various information related to the operation of the air conditioner may be stored in the main memory 910. For example, a reference indoor device number N1 may be stored in the main memory 910.
The reference indoor device number N1 may serve as a criterion for determining whether an outdoor device operates. When the number of indoor devices leaking exceeds a predetermined number, a capacity of each of the indoor heat exchangers and a capacity of each of the outdoor heat exchangers may be unbalanced deteriorating thermal efficiency or causing an excessive load on an operation of the air conditioner. Thus, when the number N of indoor device leaking exceeds the number N1 of reference indoor devices, an operation of the outdoor device may be stopped as described hereinbelow.
If a leakage in an indoor device exists, determined through refrigerant leakage detector processes, an operation of the corresponding indoor device may be stopped, and thus, the number N of indoor device leaking may be referred to as the number N of indoor devices of which operation is stopped. The leakage occurrence indoor device number detector 920 may detect the number N of indoor devices in which a leakage of refrigerant is detected. For example, the leakage occurrence indoor device number detector 920 may detect whether each of indoor device fans 150 operates to detect the number of indoor device fans for which operations are stopped. Also, whether each of the first and second valves 250 and 260 is blocked or closed may be detected to detect the number of indoor devices for which both of the first and second valves 250 and 260 is blocked or closed. The leakage occurrence indoor device number detector 920 may be called “counter 920”.
Although the main controller 900, the first indoor controller 600, the second indoor device controller 700, and the third indoor device controller 800 may be distinguished or separated from each other, embodiments are not limited thereto. For example, operations of each of the controllers may be performed by one controller. The main controller 900 and each of the indoor device controller 600, 700, and 800 may be commonly called a “controller”.
Although the memory 610 and the main memory 910 may be distinguished or separate from each other, embodiments are not limited thereto. The memory 610 and the main memory 910 may be commonly called a “memory”.
FIG. 5 is a flowchart illustrating a method of controlling an air conditioner according to another embodiment. Referring to FIG. 5, in an air conditioner according to this embodiment, a leakage occurrence indoor device number detector, such as leakage occurrence indoor device number detector 920 of FIG. 4, may detect the number N of indoor device in which leakage of a refrigerant occurs, in step S500. Also, it may be determined whether the number N of leakage occurrence indoor device exceeds a number N1 of reference indoor devices, in step S510.
When the number N of leakage occurrence indoor devices exceeds the number N1 of reference indoor devices, a user may be informed that the number N of leakage occurrence indoor devices exceeds the number N1 of reference indoor devices by an abnormality informing device, in step S520. As described above, the abnormality informing device may include a display or speaker.
In step S530, a main controller, such as main controller 900 of FIG. 4, may stop an operation of an outdoor device, such as outdoor device 100 of FIG. 1. More particularly, the main controller may stop an operation of a compressor, such as compressor 110 of FIG. 1, and an outdoor device fan, such as an outdoor device fan 150 of FIG. 4, which are disposed in the outdoor device.
According to an air conditioner and method of controlling an air conditioner according to embodiments, operation of the air conditioner may be prevented from being unnecessarily stopped due to misdetection by a leakage detector. More particularly, leakage of refrigerant may be detected two times to block circulation of the refrigerant, thereby improving reliability of the leakage detector. Also, a valve in a side of a circulation tube having a relatively high pressure may be blocked or closed to improve efficiency of leakage blocking.
Also, in a case of a multi-type air conditioner including a plurality of indoor devices, operation of only an actual indoor device in which the refrigerant leaks may be stopped. Also, as the operation of the outdoor device may be stopped in consideration of condensation/evaporation of each of the indoor and outdoor heat exchangers, deterioration in efficiency and damage to the air conditioner may be prevented.
Embodiments disclosed herein provide an air conditioner and a method of controlling an air conditioner.
Embodiments disclosed herein provide an air conditioner that may include a compressor that compresses an inflow refrigerant to discharge the compressed refrigerant; an outdoor heat exchanger in which outdoor air introduced into an outdoor device and the refrigerant may be heat-exchanged with each other; an indoor heat exchanger in which indoor air introduced into an indoor device and the refrigerant may be heat-exchanged with each other; valves respectively disposed in an inflow-side tube and a discharge-side tube of the indoor heat exchanger; and a refrigerant leakage detector that directly or indirectly detects leakage of the refrigerant, wherein, when the leakage of the refrigerant is detected, the valves are blocked in stages.
The valves may include a first valve disposed in the inflow-side tube of the indoor heat exchanger; and a second valve disposed in the discharge-side tube of the indoor heat exchanger. When the leakage of the refrigerant is detected, the first valve may be blocked earlier than the second valve. When the leakage of the refrigerant is detected for a preset or predetermined time (t2) after the first valve is blocked or closed, the second valve may be blocked or closed. When the leakage of the refrigerant is not detected for a preset or predetermined time (t2) after the first valve is blocked or closed, the first valve may be opened, and the second valve may be maintained in an open state.
One of the valves may be an outdoor expansion valve or indoor expansion valve.
The indoor heat exchanger may be provided in plurality, and the air conditioner may further include a branch tube that guides the refrigerant into each of the indoor heat exchangers. The branch tube may be disposed between the outdoor heat exchanger and the indoor heat exchanger, and one of the valves may be disposed between the branch tube and the indoor heat exchanger.
The air conditioner may further include a counter that detects a number (N) of indoor units or devices in which the leakage of the refrigerant occurs. When the number (N) of leakage occurrence indoor units detected by the counter exceeds a preset number (N1), an operation of the outdoor unit or device may be stopped.
When the number (N) of leakage occurrence indoor units exceeds the preset number (N1), operations of the compressor and an outdoor unit or device fan may be stopped.
Embodiments disclosed herein further provide an air conditioner that may include a first valve disposed in a refrigerant suction-side tube of an indoor heat exchanger to selectively block a flow of a refrigerant on the basis of a cooling mode; a second valve disposed in a refrigerant discharge-side tube of the indoor heat exchanger to selectively block the flow of the refrigerant on the basis of the cooling mode; a flow switching valve that switches a flow direction of the refrigerant according to an operation mode of the air conditioner; a refrigerant leakage detection part or detector that detects a refrigerant leaking into an indoor space; and a control part or controller that successively closes the first and second valves when the leakage of the refrigerant is detected by the refrigerant leakage detection part. The control part may close the first valve earlier than the second valve in a cooling mode and close the second valve earlier than the first valve in a heating mode.
The air conditioner may further include an indoor unit or device fan that guides a flow of indoor air so that the indoor air passes through the indoor heat exchanger. The control part may enable the indoor unit fan to continuously operate while one valve of the first and second valves is blocked. When all of the first and second valves are blocked, the control part may stop an operation of the indoor unit fan.
Embodiments disclosed herein provide a method of controlling an air conditioner that may include firstly detecting leakage of a refrigerant in an indoor space in which air-conditioning is performed; closing a first valve disposed in a refrigerant inflow-side tube of an indoor heat exchanger when the leakage of the refrigerant is detected firstly; secondarily detecting the leakage of the refrigerant after the first valve is blocked; and closing a second valve disposed in a refrigerant discharge-side tube of the indoor heat exchanger when the leakage of the refrigerant is detected secondarily. The closing of the valves may be performed when a time at which the leakage of the refrigerant is detected exceeds a preset reference time. When the leakage of the refrigerant is not detected secondarily, the method may further include opening the first valve.
When the leakage of the refrigerant is detected firstly, the method may further include determining whether an operation mode of the air conditioner is a cooling mode or a heating mode, and the first valve disposed in the refrigerant inflow-side tube of the indoor heat exchanger may be blocked according to the determined operation mode. When the leakage of the refrigerant is detected secondarily, the method may further include stopping an operation of an indoor unit or device.
When the number (N) of indoor units or devices in which the leakage of the refrigerant occurs exceeds the number (N1) of predetermined reference indoor units, the method may further include stopping an operation of an outdoor unit or device.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.

Claims

What is claimed is:

1. An air conditioner, comprising:

a compressor that compresses a refrigerant and discharges the compressed refrigerant;

an outdoor heat exchanger in which outdoor air introduced into an outdoor device and the refrigerant are heat-exchanged with each other;

at least one indoor heat exchanger in which indoor air introduced into an indoor device and the refrigerant are heat-exchanged with each other;

a plurality of valves disposed respectively in an inflow-side tube and a discharge-side tube of the at least one indoor heat exchanger; and

a refrigerant leakage detector that directly or indirectly detects leakage of the refrigerant, wherein when the leakage of the refrigerant is detected, the plurality of valves is blocked in stages.

2. The air conditioner according to claim 1, wherein the plurality of valves comprises:

a first valve disposed in the inflow-side tube of the indoor heat exchanger; and

a second valve disposed in the discharge-side tube of the indoor heat exchanger, wherein when the leakage of the refrigerant is detected, the first valve is blocked or closed earlier than the second valve.

3. The air conditioner according to claim 2, wherein when the leakage of the refrigerant is detected for a predetermined period of time after the first valve is blocked or closed, the second valve is blocked or closed.

4. The air conditioner according to claim 2, wherein, when the leakage of the refrigerant is not detected for a predetermined period of time (t2) after the first valve is blocked or closed, the first valve is opened, and the second valve is maintained in an open state.

5. The air conditioner according to claim 1, wherein one of the plurality of valves is an outdoor expansion valve or an indoor expansion valve.

6. The air conditioner according to claim 1, wherein the at least one indoor heat exchanger comprises a plurality of indoor heat exchangers, and wherein the air conditioner further comprises a plurality of branch tubes that guides, respectively, the refrigerant into each of the plurality of indoor heat exchangers.

7. The air conditioner according to claim 6, wherein the plurality of branch tubes is disposed between the outdoor heat exchanger and the plurality of indoor heat exchangers, and wherein one of the plurality of valves is disposed in the plurality of branch tubes.

8. The air conditioner according to claim 6, further comprising a counter that detects a number (N) of indoor devices in which the leakage of the refrigerant occurs, and wherein when the number (N) of indoor devices in which the leakage of the refrigerant occurs detected by the counter exceeds a predetermined number (N1), an operation of the outdoor device is stopped.

9. The air conditioner according to claim 8, wherein when the number (N) of indoor devices in which the leakage of the refrigerant occurs exceeds the predetermined number (N1), operations of the compressor and an outdoor device fan are stopped.

10. An air conditioner, comprising:

a first valve disposed in a refrigerant suction-side tube of an indoor heat exchanger to selectively block a flow of a refrigerant, with respect to a cooling mode;

a second valve disposed in a refrigerant discharge-side tube of the indoor heat exchanger to selectively block the flow of the refrigerant, with respect to the cooling mode;

a flow switching valve that switches a flow direction of the refrigerant according to an operation mode of the air conditioner;

a refrigerant leakage detector that detects a refrigerant leaking into an indoor space; and

a controller that successively closes the first and second valves when the leakage of the refrigerant is detected by the refrigerant leakage detector.

11. The air conditioner according to claim 10, wherein the controller closes the first valve earlier than the second valve in the cooling mode and closes the second valve earlier than the first valve in a heating mode.

12. The air conditioner according to claim 10, further comprising an indoor device fan that guides a flow of indoor air so that the indoor air passes through the indoor heat exchanger.

13. The air conditioner according to claim 12, wherein the controller enables the indoor device fan to continuously operate while one valve of the first and second valves is blocked or closed.

14. The air conditioner according to claim 13, wherein when both of the first and second valves are blocked or closed, the controller stops an operation of the indoor device fan.

15. A method of controlling an air conditioner, the method comprising:

detecting leakage of a refrigerant in an indoor space in which air-conditioning is performed;

closing a first valve disposed in a refrigerant inflow-side tube of an indoor heat exchanger when the leakage of the refrigerant is detected;

thereafter, detecting the leakage of the refrigerant after the first valve is blocked or closed; and

closing a second valve disposed in a refrigerant discharge-side tube of the indoor heat exchanger when the leakage of the refrigerant is detected thereafter.

16. The method according to claim 15, wherein the closing of the valves is performed when a time during which the leakage of the refrigerant is detected exceeds a predetermined reference time.

17. The method according to claim 15, wherein when the leakage of the refrigerant is not detected thereafter, the method further comprises opening the first valve.

18. The method according to claim 15, wherein when the leakage of the refrigerant is first detected, the method further comprises determining whether an operation mode of the air conditioner is a cooling mode or a heating mode, and wherein the first valve disposed in the refrigerant inflow-side tube of the indoor heat exchanger is blocked or closed according to the determined operation mode.

19. The method according to claim 15, wherein when the leakage of the refrigerant is detected thereafter, the method further comprises stopping an operation of an indoor device.

20. The method according to claim 15, wherein when a number (N) of indoor devices in which the leakage of the refrigerant occurs exceeds a predetermined reference number (N1), the method further comprises stopping an operation of an outdoor device.