AIR CONDITIONER

Abstract

An air conditioner is provided that may include an indoor device and an outdoor device. The outdoor device may include at least one compressor, an outdoor heat exchanger, a supercooling device that supercools a refrigerant, a first refrigerant pipe that allows the supercooling device to communicate with a suction side of the compressor, a first valve disposed in or on the first refrigerant pipe, a second refrigerant pipe that connects the compressor to the first refrigerant pipe, and at least one second valve disposed in or on the second refrigerant pipe. In a first refrigerant flow mode, a refrigerant flowing into the supercooling device may be introduced into the at least one compressor through the second refrigerant pipe. In a second refrigerant flow mode, a refrigerant compressed by the at least one compressor may be discharged into the second refrigerant pipe.

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. 10-2011-0110386, filed in Korea on Oct. 27, 2011, which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field

An air conditioner is disclosed herein.

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 block diagram of a refrigerant cycle of an air conditioner according to an embodiment;

FIG. 2 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in a normal mode according to an embodiment;

FIG. 3 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in an injection mode according to an embodiment; and

FIG. 4 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in a refrigerant bypass mode according to an embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference to the accompanying drawings. Where possible, like reference numerals have been used to indicate like elements. Also, in the description of embodiments, detailed description of well-known related structures or functions has been omitted.

Also, in the description of embodiments, terms such as first, second, A, B, (a), or (b) may be used herein when describing components. Each of these terminologies is not used to define an essence, order, or sequence of a corresponding component, but is used merely to distinguish the corresponding component from other component(s). It should be noted that if it is described in the specification that one component is “connected,” “coupled”, or “joined” to another component, the former may be directly “connected”, “coupled”, and “joined” to the latter or “connected”, “coupled”, and “joined” to the latter via another component.

In general, air conditioners are apparatuses that cool/heat an indoor space or purify air using a refrigerant cycle including a compressor, condenser, an expansion mechanism, and an evaporator. Air conditioners may be classified as an air conditioner in which a single indoor device is connected to a single outdoor device and a multi-type air conditioner in which a plurality of indoor devices are connected to one or more outdoor devices to provide the effect of a plurality of air conditioners.

FIG. 1 is a block diagram of a refrigerant cycle of an air conditioner according to an embodiment. Referring to FIG. 1, an air conditioner according to an embodiment may include an outdoor unit or device 10 and an indoor unit or device 20 connected to the outdoor device 10 by a refrigerant pipe.

The indoor device 20 may include a plurality of indoor devices 21 and 22. For convenience of description, although one outdoor device is shown connected to two indoor devices in the embodiment of FIG. 1, the present disclosure is not limited to this number of indoor and outdoor devices. For example, two or more indoor devices may be connected to two or more outdoor devices, or one indoor device may be connected to one outdoor device. The outdoor device 10 may include a compression device 110 that compresses a refrigerant, and an outdoor heat exchanger 130, in which outdoor air may be heat-exchanged with refrigerant.

The compression device 110 may include one or more compressors. In the embodiment of FIG. 1, the compression device 110 includes a plurality of compressors 111 and 112. One of the plurality of compressors 111 and 112 may be an inverter compressor having a variable capacity and another may be a constant-speed compressor. Alternatively, all of the compressors may be constant-speed compressors or inverter compressors. The plurality of compressors 111 and 112 may be disposed in parallel. One of the plurality of compressors 111 and 112 or all of the compressors 111 and 112 may be operated according to a capacity of the indoor device 20.

A discharge side pipe of each of the compressors 111 and 112 may include an individual pipe 115 and a joint pipe 116. That is, the individual pipe 115 of each of the compressors 111 and 112 may be jointed to the joint pipe 116. Oil separators 113 and 114 that each separates oil from the refrigerant may be disposed on the individual pipe 115, respectively. The oil separated by the oil separators 113 and 114 may be returned to an accumulator 135 or each of the compressors 111 and 112.

The joint pipe 116 may be connected, for example, to a valve 120, which may be a four-way valve, that switches a flow of the refrigerant. The valve 120 may be connected to the indoor heat exchanger 130 through a connection pipe 122. Also, the valve 120 may be connected to the accumulator 135, and the accumulator 135 may be connected to the compression device 110.

The outdoor heat exchanger 130 may include a first heat exchanger part 131 and a second heat exchanger part 132. The first and second heat exchanger parts 131 and 132 may be independent heat exchangers separated from each other, or a single heat exchanger divided into two parts based on refrigerant flow. The first and second heat exchanger parts 131 and 132 may be horizontally or vertically disposed with respect to each other. Also, the first and second heat exchanger parts 131 and 132 may have the same thermal capacity or capacities different from each other.

The refrigerant within the outdoor heat exchanger 130 may be heat-exchanged with outdoor air blown by a fan motor assembly 139, which may include an outdoor fan and a fan motor. One or more fan motor assemblies may be provided. FIG. 1 illustrates one outdoor fan motor assembly; however, embodiments are not so limited.

The outdoor device 10 may further include an outdoor expansion mechanism 140. The outdoor expansion mechanism 140 does not expand a refrigerant that passes through the outdoor heat exchanger 130, but rather, expands a refrigerant which does not pass through the outdoor heat exchanger 130.

The outdoor expansion mechanism 140 may include a first outdoor expansion valve 141 connected to the first heat exchanger part 131 and a second outdoor expansion valve 142 connected to the second heat exchanger part 132. Also, a first check valve 143 may be disposed is parallel with respect to the first outdoor expansion valve 141, and a second check valve 144 may be disposed in parallel with respect to the second outdoor expansion valve 142.

The refrigerant expanded by the first outdoor expansion valve 141 may flow into the first heat exchanger part 131, and the refrigerant expanded by the second outdoor expansion valve 142 may flow into the second heat exchanger part 132. Each of the outdoor expansion valves 141 and 142 may be an electronic expansion valve (EEV), for example.

A bypass pipe assembly may be connected to the joint pipe 116. The bypass pipe may connect each of the heat exchanger parts 131 and 132 to each of the outdoor expansion valves 141 and 142. The bypass pipe assembly may include a common pipe 150 connected to the joint pipe 116, and first and second bypass pipes 151 and 152 branched from the common pipe 150. The first bypass pipe 151 may be connected to a pipe that connects the first heat exchanger part 131 to the first outdoor expansion valve 141, and the second bypass pipe 152 may be connected to a pipe that connects the second heat exchanger part 132 to the second outdoor expansion valve 142.

A first bypass valve 153 may be disposed in the first bypass pipe 151, and a second bypass valve 154 may be disposed in the second bypass pipe 152. Each of the bypass valves 153 and 154 may be a solenoid valve through which a flow rate is adjustable, for example. Alternatively, the common pipe may be omitted in the bypass pipe assembly, and the first and second bypass pipes 151 and 152 may be connected to the joint pipe 116.

The bypass valves 153 and 154 may be opened during a heating operation. When the bypass valves 153 and 154 are opened, a high-temperature refrigerant compressed by the compression device 110 may flow into the bypass pipes 151 and 152. When the high-temperature refrigerant flows into the bypass pipes 151 and 152, frost on the outdoor heat exchanger 130 may be removed by the high-temperature refrigerant.

The outdoor expansion mechanism 140 may be connected to a supercooler 160 by a liquid pipe 34. A supercooling pipe 162, which may bypass refrigerant that has passed through the supercooler 160 back into the supercooler, 160 may be connected to the liquid pipe 34. Because the structure of the supercooler 160 and a connection relationship between the pipes may be realized by previously well known structure, their detailed description has been omitted. A supercooling valve 164 that adjusts a flow rate of the refrigerant and expands the refrigerant may be disposed in the supercooling pipe 162. The supercooling valve 164 may adjust a flow rate of the refrigerant flowing into a first refrigerant pipe 170, which will be described hereinafter.

In this embodiment, the supercooler 160, the supercooling pipe 162, and the supercooling valve 164 may function together to supercool a refrigerant. Thus, the supercooler 160, the supercooling pipe 162, and the supercooling valve 164 may be commonly called a supercooling device.

The first refrigerant pipe 170, which may communicate with the supercooling pipe 162 and be connected to the accumulator 135, may be connected to the supercooler 160. For example, the first refrigerant pipe 170 may be connected to a pipe 121 that connects the valve 120 to the accumulator 135. Also, a first valve 172 may be disposed or on in the first refrigerant pipe 170. The first valve 172 may be a solenoid valve, for example. Although the first refrigerant pipe 170 may be connected to the pipe 121 connected to the accumulator 135 according to this embodiment, embodiments are not limited thereto. For example, the first refrigerant pipe 170 may be connected to the accumulator 135 or between the compression device 110 and the accumulator 135. That is, in this embodiment, the first refrigerant pipe 170 may allow the supercooling device to communicate with a suction side of the compression device 110.

A second refrigerant pipe may be connected to the first refrigerant pipe 170. The second refrigerant pipe may include a common pipe 180, and first and second branch pipes 182 and 184 branched from the common pipe 180. The first branch pipe 182 may be connected to the first compressor 111, and the second branch pipe 184 may be connected to the second compressor 112.

In this embodiment, each of the compressors 111 and 112 may be a compressor that enables the refrigerant to be compressed in multiple stages. Also, each of the branch pipes 182 and 184 may communicate with a specific compression chamber (a compression chamber into which a refrigerant compressed more than once is introduced) of a plurality of compression chambers. For example, in a case in which the compressor has two compression chambers (for example, a refrigerant compressed in a first compression chamber is compressed again in a second compression), each of the branch pipes 182 and 184 may communicate with the second compression chamber. Also, in a case in which the compressor has three or more compression chambers, each of the branch pipes 182 and 184 may communicate with one of the second compression chamber and the next compression chamber. A lower-pressure region may be defined as a suction side of the compressor, and a high-pressure region may be defined as a discharge side of the compressor. A region in which each of the branch pipes 183 and 185 is connected may be defined as a middle-pressure region.

A first branch valve 183 may be disposed in the first branch pipe 182, and a second branch valve 185 may be disposed in the second branch pipe 184. For example, each of the branch valves 183 and 185 may be a solenoid valve. The first and second branch valves 183 and 185 may be referred to as a second valve in reference to the first valve 172. Alternatively, a valve may be omitted in the branch pipe, and a valve may be disposed in the common pipe. Further alternatively, each of the branch pipes 183 and 185 may be connected to the first refrigerant pipe.

The outdoor device 10 may be connected to the indoor device 20 through a gas pipe 31 and the liquid pipe 34. The gas pipe 31 may be connected to the valve 120, and the liquid pipe 34 may be connected to the outdoor expansion mechanism 140. That is, a pipe connected to both sides of the supercooler 160 may be referred to as the liquid pipe 34.

Each of the indoor devices 21 and 22 may include an indoor heat exchanger 211 and 221, an indoor fan 212 and 222, and an indoor expansion mechanism 213 and 223, respectively. Each of the indoor expansion mechanisms 213 and 223 may be an EEV, for example.

Hereinafter, a refrigerant flow within an air conditioner according to an embodiment will be described.

An operation mode of an air conditioner according to embodiments may include a normal mode (a normal cooling mode, a normal heating mode, or a third refrigerant flow mode), an injection mode (or a first refrigerant flow mode), and a refrigerant bypass mode (a second refrigerant flow mode). The above-described modes may be classified according to a flow direction of the refrigerant.

FIG. 2 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in a normal mode according to an embodiment. For example, FIG. 2 illustrates a refrigerant flow when the air conditioner is operated in a cooling mode.

Referring to FIG. 2, when the air conditioner is operated in the normal cooling mode, a high-temperature, high-pressure refrigerant discharged from the compression device 110 of the outdoor device 10 may flow toward the outdoor heat exchanger 130 by switching the refrigerant flow through the valve 120.

The refrigerant flowing toward the outdoor heat exchanger 130 may be condensed while flowing into each of the heat exchanger parts 131 and 132. In the normal cooling mode of the air conditioner, the bypass valves 153 and 154 and the outdoor expansion valves 141 and 142 may be closed.

Thus, the refrigerant discharged from the compression device 110 may not pass through each of the bypass pipes 151 and 152. Also, the refrigerant discharged from each of the heat exchanger parts 131 and 132 may pass through each of the check valves 143 and 144.

Then, the condensed refrigerant may flow into the supercooler 160. A portion of the refrigerant that passes through the supercooler 160 may be expanded by the supercooling valve 164 while flowing through the supercooling pipe 162. The refrigerant expanded by the supercooling valve 164 may be re-introduced into the supercooler 160 and heat-exchanged with the condensed refrigerant flowing along the liquid pipe 34.

According to one embodiment, the refrigerant flowing along the supercooling pipe 162 may drop in temperature and pressure while passing through the supercooling valve 164. Thus, the refrigerant passing through the supercooling valve 164 may have a temperature relatively less than that of the refrigerant flowing in the liquid pipe 34. Thus, the condensed refrigerant may be supercooled while passing through the supercooler 160. As the condensed refrigerant is supercooled, a low-temperature refrigerant may be introduced into the indoor heat exchanger. Thus, a quantity of heat absorbed from the indoor air may further increase to improve an overall cooling performance of the air conditioner.

In a case in which the air conditioner is operated in a normal heating mode, the refrigerant may also be supercooled. The supercooled refrigerant may be introduced into the outdoor heat exchanger 130. Thus, the heating performance of the air conditioner may be improved.

The refrigerant within the supercooling pipe 162 may pass through the supercooler 160 to flow into the first refrigerant pipe 170. In the normal cooling mode of the air conditioner, the first valve 172 may be opened, and each of the branch valves 183 and 185 may be closed (which have the same state in the normal heating mode). Thus, the refrigerant introduced into the supercooling pipe 162 may be introduced into the accumulator 135 without being bypassed to each of the compressors 111 and 112.

The refrigerant flowing into the liquid pipe 34 may be introduced into each of the indoor devices 21 and 22. The refrigerant introduced into each of the indoor devices 21 and 22 may be introduced into each of the indoor heat exchangers 211 and 221, respectively, after the refrigerant is expanded by the indoor expansion mechanisms 213 and 223. The refrigerant may be evaporated while flowing through each of the indoor heat exchangers 211 and 221, and then, may be moved into the outdoor device 10 along the gas pipe 31. Then, the refrigerant may be introduced into the accumulator 135 via the valve 120. A gaseous portion of the refrigerant introduced into the accumulator 135 may be introduced into the compression device 110.

FIG. 3 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in an injection mode according to an embodiment. For example, FIG. 3 illustrates a refrigerant flow when the air conditioner is operated in the injection mode.

Referring to FIG. 3, the injection mode of the air conditioner may be basically the same as the normal cooling mode except for operations of the first valve 172 and the branch valves 183 and 185. Thus, only features which are different from those of the normal cooling mode of the air conditioner discussed above will be described hereinbelow.

In a case in which a differential pressure between a high pressure and a low pressure of the compression device 110 is equal to or greater than a reference pressure (the high pressure is equal to or greater than the reference pressure or the low pressure is equal to or less than the reference pressure) or a compression ratio (a ratio of a high pressure to a low pressure) is equal to or less than a reference compression ratio during the normal cooling mode of the air conditioner, the first valve 172 may be closed and each of the branch valves 183 and 185 may be opened.

Thus, the refrigerant discharged from the supercooler 160 into the first refrigerant pipe 170 may be injected into each of the compressors 111 and 112 along the common pipe 180 and each of the branch pipes 182 and 184. The refrigerant injected into the compressors 111 and 112 may have a middle pressure between a pressure of the discharge side of the compressor and a pressure of the suction side of the compressor.

In this embodiment, since the refrigerant having the middle pressure is injected into each of the compressors 111 and 112, a differential pressure between the high pressure and the low pressure of each of the compressors 111 and 112 may be reduced. Thus, the refrigerant discharged from the compressors 111 and 112 to flow into the condenser (the outdoor heat exchanger during the cooling or the indoor heat exchanger during the heating) may increase in flow rate to improve cycle performance.

In a case in which a differential pressure between a high pressure and a low pressure is less than the reference pressure or a compression ratio (a ratio of a high pressure to a low pressure) is greater than the reference compression ratio during the injection mode of the air conditioner, the branch valves 183 and 185 may be closed and the first valve 172 opened. Thus, the air conditioner may be operated in the normal cooling mode.

FIG. 4 is a block diagram illustrating a flow of a refrigerant when an air conditioner is operated in a refrigerant bypass mode according to an embodiment. For example, FIG. 4 illustrates a refrigerant flow when the air conditioner is switched from the cooling mode into the refrigerant bypass mode.

Referring to FIG. 4, the refrigerant bypass mode of the air conditioner may be basically the same as the normal cooling mode except for operations of the branch valves 183 and 185 and the supercooling valve 164. Thus, only features which are different from those of the normal cooling mode of the air conditioner discussed above will be described hereinbelow.

In a case in which a cycle load increases (for example, a high pressure of the compression device is greater than the reference pressure) during the normal cooling mode of the air conditioner, the supercooling valve 164 may be closed and each of the branch valves 183 and 185 opened.

Thus, the middle-pressure refrigerant compressed in a portion of the plurality of compression chambers of each of the compressors 111 and 112 may be bypassed to the branch pipes 182 and 184. The refrigerant bypassed to the branch pipes 182 and 184 may be introduced into the first refrigerant pipe 170 via the common pipe 180. Then, the refrigerant may be introduced into the accumulator 135 via the first refrigerant pipe 170.

According to this embodiment, as the middle-pressure refrigerant within the compressors 111 and 112 may be discharged from the compressors 111 and 112 to flow into the accumulator 135, a flow rate of each of the compressors 111 and 112 may decrease. Thus, the high-pressure refrigerant within the compressors 111 and 112 may decrease in pressure to reduce cycle load.

Also, according to this embodiment, as the branch pipes serve as channels for injecting the refrigerant as well as channels for discharging the middle-pressure refrigerant, it may be unnecessary to provide a separate pipe that bypasses the refrigerant. Thus, the refrigerant cycle may be simplified in structure and manufacturing costs reduced.

Also, as middle-pressure refrigerant is bypassed in the compressors 111 and 112, a flow rate of the bypassed refrigerant may be less than that of the bypassed high-pressure refrigerant. Thus, it is unnecessary to provide a separate capillary in the second refrigerant pipe.

In a case in which the cycle load decreases (for example, the compression device has a high pressure equal to or less than the reference pressure) during the refrigerant bypass mode of the air conditioner, the branch valves 183 and 185 may be closed and the supercooling valve 164 opened. Thus, the air conditioner may be operated in the normal cooling mode.

Although the case in which the air conditioner is operated in the normal cooling mode is described as an example, the present disclosure is not limited thereto. For example, the foregoing embodiment may be applied to a case in which the air conditioner is operated in a normal heating mode. That is, the normal heating mode of the air conditioner may be switched into the injection mode or the refrigerant bypass mode.

Embodiments disclosed herein provide an air conditioner that may include an indoor unit or device and an outdoor unit or device. The outdoor unit or device may include at least one compressor; an outdoor heat exchanger; a supercooling unit or device configured to supercool a refrigerant; a first refrigerant pipe that allows the supercooling unit to communicate with a suction side of the at least one compressor; a first valve disposed at the first refrigerant pipe; a second refrigerant pipe that connects the at least one compressor to the first refrigerant pipe; and a second valve disposed at the second refrigerant pipe, wherein, in a first refrigerant flow mode, a refrigerant flowing into the supercooling unit is introduced into the at least one compressor through the second refrigerant pipe, and in a second refrigerant flow mode, a refrigerant compressed by the at least one compressor is discharged into the second refrigerant pipe.

Even though all of the elements of embodiments disclosed herein may be coupled or operated in a combined state, the present disclosure is not limited to such embodiments. That is, all elements may be selectively coupled with each other without departing from the scope of the invention. Further, when it is described that one comprises (or includes or has) some elements, it should be understood that it may comprise (or include or has) only those elements, or it may comprise (or include or have) other elements as well as those elements if there is no specific limitation. Unless otherwise specifically defined herein, all terms including technical or scientific terms are to be given meanings understood by those skilled in the art. Like terms defined in dictionaries, generally used terms need to be construed as its meaning used in technical contexts and are not construed as ideal or excessively formal meanings unless otherwise clearly defined herein.

Although embodiments have been described with reference to a number of illustrative embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the embodiments disclosed herein should be considered in descriptive sense only and not for purposes of limitation, and also the technical scope is not limited to the disclosed embodiments. Further, is defined not by the detailed description but by the appended claims, and all differences within the scope should be construed as being contained in the present disclosure.

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

1. An air conditioner, comprising:

at least one indoor device; and

an outdoor device in communication with the at least one indoor device, wherein the outdoor device comprises: at least one compressor; an outdoor heat exchanger; a supercooling device configured to supercool a refrigerant; a first refrigerant pipe that allows the supercooling device to communicate with a suction side of the at least one compressor; a first valve disposed at or on the first refrigerant pipe; a second refrigerant pipe that connects the at least one compressor to the first refrigerant pipe; and

at least one second valve disposed at or on the second refrigerant pipe, wherein, in a first refrigerant flow mode, a refrigerant flowing into the supercooling device is introduced into the at least one compressor through the second refrigerant pipe, and in a second refrigerant flow mode, a refrigerant compressed by the at least one compressor is discharged into the second refrigerant pipe.

2. The air conditioner according to claim 1, wherein, in a third refrigerant flow mode, the refrigerant flowing into the supercooling device flows toward the suction side of the at least one compressor via the first refrigerant pipe.

3. The air conditioner according to claim 2, wherein the first refrigerant flow mode is performed in a case in which a differential pressure between a high pressure and a low pressure of the at least one compressor exceeds a reference pressure or a compression ratio of the high pressure to the low pressure is equal to or less than a reference compression ratio.

4. The air conditioner according to claim 3, wherein, when a starting condition of the first refrigerant flow mode is satisfied during the third refrigerant flow mode, the first refrigerant flow mode is performed.

5. The air conditioner according to claim 3, wherein, when a starting condition of the second refrigerant flow mode is satisfied during the third refrigerant flow mode, the second refrigerant flow mode is performed.

6. The air conditioner according to claim 2, wherein, in the first refrigerant flow mode, the first valve is closed and the at least one second valve is opened.

7. The air conditioner according to claim 2, wherein the second refrigerant flow mode is performed in a case in which a high-pressure of the at least one compressor exceeds a reference pressure.

8. The air conditioner according to claim 7, wherein the supercooling device further comprises a supercooling valve that adjusts a flow rate of the refrigerant flowing into the first refrigerant pipe, and in the second refrigerant flow mode, the supercooling valve is closed and the first valve and that at least one second valve are opened.

9. The air conditioner according to claim 8, wherein, in the third refrigerant flow mode, the supercooling valve and the first valve are opened and the at least one second valve is closed.

10. The air conditioner according to claim 1, wherein the at least one compressor comprises a plurality of compression chambers that compresses the refrigerant in multiple stages, and wherein the second refrigerant pipe communicates with one of the plurality of compression chambers into which the refrigerant compressed more than once is introduced.

11. The air conditioner according to claim 1, wherein the at least one compressor comprises a plurality of compressors, and wherein the second refrigerant pipe comprises a common pipe connected to the first refrigerant pipe and a plurality of branch pipes branched from the common pipe, and connected, respectively, to the plurality of compressors.

12. The air conditioner according to claim 11, wherein the at least one second valve is disposed at or on the common pipe.

13. The air conditioner according to claim 11, wherein the at least one second valve comprises a plurality of second valves disposed at or on each of the plurality of branch pipes, respectively.

14. The air conditioner according to claim 1, wherein the at least one compressor comprises a plurality of compressors, wherein the second refrigerant pipe comprises a plurality of branch pipes connected to the first refrigerant pipe and to each of the plurality of compressors, and wherein the at least one second valve comprises a plurality of second valves disposed at or on each of the plurality of branch pipes, respectively.

15. The air conditioner of claim 1, wherein the first refrigerant flow mode comprises a refrigerant injection mode and the second refrigerant flow mode comprises a refrigerant bypass mode.

16. The air conditioner of claim 2, wherein the first refrigerant flow mode comprises a refrigerant injection mode, the second refrigerant flow mode comprises a refrigerant bypass mode, and the third refrigerant flow mode comprises a normal refrigerant flow mode.

17. The air conditioner of claim 16, wherein the normal refrigerant flow mode comprises a normal cooling mode or a normal heating mode.

18. The air conditioner of claim 1, further comprising a liquid pipe, through which liquid refrigerant flows from the outdoor device to the at least one indoor device.

19. The air conditioner of claim 1, further comprising a gas pipe, though which gaseous refrigerant flows from the at least one indoor device to the indoor device.

20. An air conditioner, comprising:

at least one indoor device; and

an outdoor device in communication with the at least one indoor device, wherein the outdoor device comprises: at least one compressor; an outdoor heat exchanger; a supercooling device configured to supercool a refrigerant; a first refrigerant pipe that provides communication between the supercooling device and a suction side of the at least one compressor; a first valve disposed on the first refrigerant pipe; a second refrigerant pipe that provides communication between the at least one compressor and the first refrigerant pipe; and

at least one second valve disposed on the second refrigerant pipe, wherein, in a refrigerant injection mode, a refrigerant flowing into the supercooling device is introduced into the at least one compressor through the second refrigerant pipe, and in a refrigerant bypass mode, a refrigerant compressed by the at least one compressor is discharged into the second refrigerant pipe.

21. The air conditioner according to claim 20, wherein, in a normal refrigerant flow mode, the refrigerant flowing into the supercooling device flows toward the suction side of the at least one compressor via the first refrigerant pipe.

22. The air conditioner according to claim 21, wherein the refrigerant injection mode is performed in a case in which a differential pressure between a high pressure and a low pressure of the at least one compressor exceeds a reference pressure or a compression ratio of the high pressure to the low pressure is equal to or less than a reference compression ratio.

23. The air conditioner according to claim 21, wherein, in the refrigerant injection mode, the first valve is closed and the at least one second valve is opened.

24. The air conditioner according to claim 21, wherein the refrigerant bypass mode is performed in a case in which a high-pressure of the at least one compressor exceeds a reference pressure.

25. The air conditioner according to claim 24, wherein the supercooling device further comprises a supercooling valve that adjusts a flow rate of the refrigerant flowing into the first refrigerant pipe, and in the refrigerant bypass mode, the supercooling valve is closed and the first valve and the at least one second valve are opened.

26. The air conditioner according to claim 25, wherein, in the normal refrigerant flow mode, the supercooling valve and the first valve are opened and the at least one second valve is closed.