Abstract:
An air conditioning system includes a compressor; an outdoor heat exchanger that discharges evaporated refrigerant; and a first pipe coupling the outdoor heat exchanger and the compressor, where the first pipe allows the outdoor heat exchanger to receive at least a portion of the compressed refrigerant from the compressor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2008-0083629 (filed on Aug. 27, 2008), which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    The present disclosure relates to an air conditioning system, and more particularly, to an air conditioning system that can be used for both cooling and heating. 
         [0003]    In general, an air conditioning system includes a compressor, a four-way valve, an indoor heat exchanger, and an outdoor heat exchanger that are used to perform heat exchange cycles for cooling or heating an indoor area. In heating mode, the outdoor heat exchanger is operated as an evaporator, and the indoor heat exchanger is operated as a condenser. In detail, indoor heating is performed as follows: while refrigerant is evaporated in the outdoor heat exchanger, heat is exchanged between the refrigerant and outdoor air; the refrigerant is then compressed to a high-temperature and high-pressure state by the compressor; and while the compressed refrigerant is condensed at the indoor heat exchanger, heat is exchanged between the refrigerant and indoor air. 
         [0004]    A refrigerant heating device can be used to heat the refrigerant evaporated in the outdoor heat exchanger in heating mode. That is, in the case where refrigerant is not smoothly evaporated in the outdoor heat exchanger due to a very low outdoor temperature, the refrigerant is heated before the refrigerant is transferred to the compressor. In more detail, refrigerant condensed at the indoor heat exchanger is evaporated at the outdoor heat exchanger or heated by the refrigerant heating device, and the refrigerant is transferred to the compressor. 
       SUMMARY 
       [0005]    Embodiments provide an air conditioning system in which refrigerant is not accumulated in an outdoor heat exchanger in heating mode. 
         [0006]    In one embodiment, an air conditioning system includes a compressor; an outdoor heat exchanger that discharges evaporated refrigerant; and a first pipe coupling the outdoor heat exchanger and the compressor, where the first pipe allows the outdoor heat exchanger to receive at least a portion of the compressed refrigerant from the compressor. 
         [0007]    In another embodiment, an air conditioning system includes an outdoor heat exchanger; a compressor; a heater; a first pipe coupling the outdoor heat exchanger and the heater; and a second pipe coupling the first pipe and the compressor. 
         [0008]    According to the present disclosure, the air conditioning system can be operated more stably. 
         [0009]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIGS. 1 and 2  are views for illustrating flows of refrigerant in an air conditioning system when the air conditioning system is operated in heating mode according to a first embodiment. 
           [0011]      FIG. 3  is a view for illustrating flows of refrigerant in the air conditioning system when the air conditioning system is operated in cooling mode according to the first embodiment. 
           [0012]      FIG. 4  is view for illustrating flows of refrigerant in an air conditioning system when the air conditioning system is operated in heating mode according to a second embodiment. 
           [0013]      FIG. 5  is a view for illustrating flows of refrigerant in heating mode according to a third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0014]    An air conditioning system will now be described in more detail with reference to the accompanying drawings according to a first embodiment. 
         [0015]      FIGS. 1 and 2  are views for illustrating flows of refrigerant in an air conditioning system when the air conditioning system is operated in heating mode according to a first embodiment, and  FIG. 3  is a view for illustrating flows of refrigerant in the air conditioning system when the air conditioning system is operated in cooling mode according to the first embodiment. 
         [0016]    Referring to  FIGS. 1 to 3 , the air conditioning system is used to cool or heat an indoor area through heat exchange cycles in which refrigerant exchanges heat with indoor air and outdoor air. The air conditioning system includes a plurality of indoor units  100  and  100 ′, and an outdoor unit  200 , and a refrigerant heating device  300 . 
         [0017]    In more detail, the indoor units  100  and  100 ′ include indoor heat exchangers  110  and  110 ′, respectively. The indoor heat exchangers  110  and  110 ′ are operated as condensers in heating mode and evaporators in cooling mode. That is, in heating mode, the indoor heat exchangers  110  and  110 ′ receive refrigerant compressed by a compressor  220  (described later) and condense the refrigerant. In cooling mode, the indoor heat exchangers  110  and  110 ′ receive refrigerant condensed by an outdoor heat exchanger  210  and evaporate the refrigerant. 
         [0018]    The indoor units  100  and  100 ′ further include linear expansion valves (LEVs)  120  and  120 ′, respectively. In cooling mode, the linear expansion valves  120  and  120 ′ of the indoor units  100  and  100 ′ are used to expand refrigerant evaporated by the indoor heat exchangers  110  and  110 ′. In heating mode, the linear expansion valves  120  and  120 ′ of the indoor units  100  and  100 ′ are opened so that refrigerant can pass through the linear expansion valves  120  and  120 ′. 
         [0019]    The outdoor heat exchanger  210  is included in the outdoor unit  200 . The outdoor heat exchanger  210  is operated as an evaporator in heating mode and a condenser in cooling mode. In other words, in heating mode, the outdoor heat exchanger  210  evaporates refrigerant condensed by the indoor heat exchangers  110  and  110 ′ and transfers the evaporated refrigerant to the compressor  220 . In cooling mode, the outdoor heat exchanger  210  condenses refrigerant and transfers the condensed refrigerant to the indoor heat exchangers  110  and  110 ′. 
         [0020]    The compressor  220  is included in the outdoor unit  200 . The compressor  220  compresses refrigerant and discharges the compressed refrigerant to the indoor heat exchangers  110  and  110 ′ or the outdoor heat exchanger  210 . In more detail, the compressor  220  compresses refrigerant and discharges the compressed refrigerant to the indoor heat exchangers  110  and  110 ′ in heating mode and to the outdoor heat exchanger  210  in cooling mode. 
         [0021]    The outdoor unit  200  further includes a linear expansion valve  230 . In heating mode, the linear expansion valve  230  of the outdoor unit  200  expands refrigerant condensed by the indoor heat exchangers  110  and  110 ′ and transfers the refrigerant to the outdoor heat exchanger  210 . In cooling mode, the linear expansion valve  230  of the outdoor unit  200  is closed, or the opening of the opened linear expansion valve  230  is adjusted. 
         [0022]    The outdoor unit  200  further includes a parallel pipe  240  and a check valve  250 . The parallel pipe  240  is connected in parallel to a refrigerant pipe through which refrigerant flows to the outdoor heat exchanger  210  in heating mode. The check valve  250  is disposed at the parallel pipe  240 . 
         [0023]    The outdoor unit  200  further includes a four-way valve  260 . The four-way valve  260  is disposed at refrigerant pipes through which refrigerant compressed by the compressor  220  flows. In heating mode, the four-way valve  260  is positioned in a manner such that refrigerant compressed by the compressor  220  can flow to the indoor heat exchangers  110  and  110 ′ and refrigerant evaporated by the outdoor heat exchanger  210  can flow to the compressor  220 . In cooling mode, the four-way valve  260  is positioned in a manner such that refrigerant compressed by the compressor  220  can be discharged to the outdoor heat exchanger  210  and refrigerant condensed by the outdoor heat exchanger  210  can be transferred to the indoor heat exchangers  110  and  110 ′. 
         [0024]    The outdoor unit  200  further includes first to third connection pipes  271 ,  273 , and  275 . The first connection pipe  271  connects the outdoor heat exchanger  210  and the refrigerant heating device  300 . In heating mode, refrigerant evaporated by the outdoor heat exchanger  210  flows to the refrigerant heating device  300  through the first connection pipe  271 . The second connection pipe  273  connects the refrigerant heating device  300  to a refrigerant pipe connected from the indoor heat exchangers  110  and  110 ′ to the outdoor heat exchanger  210 . In heating mode, refrigerant condensed by the indoor heat exchangers  110  and  110 ′ flows to the refrigerant heating device  300  through the second connection pipe  273 . The third connection pipe  275  connects the compressor  220  and the refrigerant heating device  300 . In heating mode, refrigerant heated by the refrigerant heating device  300  flows to the compressor  220  through the third connection pipe  275 . 
         [0025]    The outdoor unit  200  further includes first and second valves  281  and  283 . The first valve  281  is disposed at the first connection pipe  271 . In heating mode, the first valve  281  is closed if the refrigerant heating device  300  is used to heat refrigerant. The first valve  281  is opened in cooling mode or in heating mode if the refrigerant heating device  300  is not used. The second valve  283  is disposed at the second connection pipe  273 . The second valve  283  is opened in heating mode if the refrigerant heating device  300  is used to heat refrigerant. The second valve  283  is closed in cooling mode or in heating mode if the refrigerant heating device  300  is not used. 
         [0026]    The outdoor unit  200  further includes a bypass pipe  291  and a third valve  293 . The bypass pipe  291  connects the first connection pipe  271  with a refrigerant pipe through which refrigerant discharged from the compressor  220  flows toward the indoor heat exchangers  110  and  110 ′ in heating mode. The bypass pipe  291  provides a flow path for refrigerant compressed by the compressor  220  and discharged toward the outdoor heat exchanger  210 . The third valve  293  is disposed at the bypass pipe  291 . The third valve  293  is opened when refrigerant accumulated in the outdoor heat exchanger  210  is re-circulated in a heat exchange cycle. 
         [0027]    In heating mode, the refrigerant heating device  300  heats refrigerant evaporated by the outdoor heat exchanger  210 . For this, the refrigerant heating device  300  includes an auxiliary heat exchanger  310  and a heating unit  320 . 
         [0028]    In more detail, refrigerant flows from the first connection pipe  271  or the second connection pipe  273  to the inside of the auxiliary heat exchanger  310 . The heating unit  320  heats the auxiliary heat exchanger  310  so that refrigerant flowing through the auxiliary heat exchanger  310  can be heated. 
         [0029]    An exemplary operation of the air conditioning system will now be described in detail according to the first embodiment. 
         [0030]    Referring to  FIG. 1 , in a heating mode using the refrigerant heating device  300 , the linear expansion valve  230 , the first valve  281 , and the third valve  293  of the outdoor unit  200  are closed, and the second valves  283  of the outdoor unit  200  is opened. The heating unit  320  is operated to heat refrigerant flowing through the auxiliary heat exchanger  310 . Therefore, during a heat exchange cycle, refrigerant is heated by the refrigerant heating device  300  and then directed to the compressor  220 . At this time, the four-way valve  260  is in a heating-mode position. 
         [0031]    In more detail, refrigerant compressed by the compressor  220  is discharged to the indoor heat exchangers  110  and  110 ′ through the four-way valve  260 . Then, at the indoor heat exchangers  110  and  110 ′, the refrigerant exchanges heat with indoor air and condenses. Therefore, indoor areas can be heated. 
         [0032]    Next, the refrigerant condensed at the indoor heat exchangers  110  and  110 ′ passes through the linear expansion valves  120  and  120 ′ of the indoor units  100  and  100 ′ and flows to the auxiliary heat exchanger  310  through the second connection pipe  273 . At this time, while the refrigerant flows in the second connection pipe  273  toward the auxiliary heat exchanger  310 , the refrigerant expands at the second valve  283 . Then, the refrigerant reaches the auxiliary heat exchanger  310  where the refrigerant is heated by the heating unit  320  and is discharged to the third connection pipe  275 . The refrigerant flows from the third connection pipe  275  to the compressor  220 , thereby completing one cycle of heat exchange. At this time, since the third valve  293  is in a closed state, the refrigerant compressed at the compressor  220  is not discharged to the outdoor heat exchanger  210  through the bypass pipe  291 . Furthermore, owing to the check valve  250 , the refrigerant compressed at the compressor  220  is not discharged to the outdoor heat exchanger  210  through the parallel pipe  240 . 
         [0033]    Referring to  FIG. 2 , in a heating mode using the refrigerant heating device  300 , the opened linear expansion valve  230 , the second valve  283 , and the third valve  293  of the outdoor unit  200  are opened, and the first valve  281  of the outdoor unit  200  is closed. Therefore, some of refrigerant compressed by the compressor  220  is discharged to the outdoor heat exchanger  210  through the bypass pipe  291 . 
         [0034]    In more detail, refrigerant compressed by the compressor  220  is discharged to the indoor heat exchangers  110  and  110 ′ where the refrigerant is condensed. The refrigerant condensed at the indoor heat exchangers  110  and  110 ′ is transferred to the auxiliary heat exchanger  310  and heated by the heating unit  320 . Then, the refrigerant is sucked by the compressor  220 . 
         [0035]    Meanwhile, some of the refrigerant compressed by the compressor  220  is transferred to the first connection pipe  271  through the bypass pipe  291 . At this time, since the first valve  281  is closed, the refrigerant transferred to the first connection pipe  271  is directed to the outdoor heat exchanger  210 . Since the opened linear expansion valve  230  of the outdoor unit  200  is opened, the refrigerant, together with refrigerant accumulated in the outdoor heat exchanger  210 , flows from the outdoor heat exchanger  210  to a refrigerant pipe connected from the outdoor heat exchanger  210  to the indoor heat exchangers  110  and  110 ′ and to the parallel pipe  240  where the check valve  250  is disposed. However, refrigerant condensed at the indoor heat exchangers  110  and  110 ′ flows toward the outdoor heat exchanger  210  through the refrigerant pipe connected from the outdoor heat exchanger  210  to the indoor heat exchangers  110  and  110 ′. Therefore, the refrigerant transferred to the outdoor heat exchanger  210  through the bypass pipe  291  and the first connection pipe  271 , and the refrigerant accumulated in the outdoor heat exchanger  210  are transferred to the auxiliary heat exchanger  310  through the second connection pipe  273  after they flow along some length of the refrigerant pipe connected from the outdoor heat exchanger  210  to the indoor heat exchangers  110  and  110 ′. Then, the refrigerant transferred to the auxiliary heat exchanger  310  is heated by the heating unit  320  and sucked by the compressor  220 . 
         [0036]    Refrigerant accumulated in the outdoor heat exchanger  210  may be re-circulated in this way when insufficient refrigerant circulates in a heat exchange cycle. For example, when the temperature of refrigerant discharged from the compressor  220  is equal to or higher than a reference temperature, it may be determined that the amount of refrigerant circulating in the heat exchange cycle is insufficient. 
         [0037]    Referring to  FIG. 3 , in cooling mode, the opening of the linear expansion valve  230  is adjusted, and the first valve  281  is opened but the second and third valves  283  and  293  are closed. The heating unit  320  is not operated such that refrigerant flowing through the auxiliary heat exchanger  310  is not heated. That is, during heat exchange cycles, refrigerant is not heated by the refrigerant heating device  300 . The four-way valve  260  is shifted to a cooling-mode position. 
         [0038]    In more detail, refrigerant compressed by the compressor  220  is discharged to the outdoor heat exchanger  210 . At the outdoor heat exchanger  210 , the refrigerant is condensed by heat exchange with outdoor air. 
         [0039]    The refrigerant condensed at the outdoor heat exchanger  210  is transferred to the indoor heat exchangers  110  and  110 ′. While the refrigerant is transferred from the outdoor heat exchanger  210  to the indoor heat exchangers  110  and  110 ′, the refrigerant is expanded by the linear expansion valves  120  and  120 ′ of the indoor units  100  and  100 ′. 
         [0040]    At the indoor heat exchangers  110  and  110 ′, the refrigerant is evaporated by heat exchange with indoor air. Therefore, the indoor areas can be cooled by heat exchange between the indoor air and the refrigerant at the indoor heat exchangers  110  and  110 ′. 
         [0041]    After the heat exchange, the refrigerant is transferred from the indoor heat exchangers  110  and  110 ′ to the compressor  220  through the four-way valve  260 . The compressor  220  compresses the refrigerant and discharges the compressed refrigerant to the auxiliary heat exchanger  310 . At this time, since the heating unit  320  is not operated, the refrigerant discharged to the auxiliary heat exchanger  310  is not heated by the heating unit  320 . 
         [0042]    Meanwhile, since the first valve  281  is opened, the refrigerant is discharged from the auxiliary heat exchanger  310  to the outdoor heat exchanger  210  through the first connection pipe  271 . At the outdoor heat exchanger  210 , the refrigerant is condensed by heat exchange with outdoor air. The condensed refrigerant is transferred to the indoor heat exchangers  110  and  110 ′ through the refrigerant pipe connected from the outdoor heat exchanger  210  to the indoor heat exchangers  110  and  110 ′, and the parallel pipe  240  connected in parallel to the refrigerant pipe. 
         [0043]    An air conditioning system will now be described in detail with reference to the accompanying drawing according to a second embodiment. 
         [0044]      FIG. 4  is view for illustrating flows of refrigerant in an air conditioning system when the air conditioning system is operated in heating mode according to a second embodiment. In the current embodiment, similar elements as those in the first embodiment will not be described in detail. 
         [0045]    Referring to  FIG. 4 , in the current embodiment, a outdoor unit  200  includes a bypass pipe  577  (hereinafter, referred to as a second bypass pipe to distinguish it from a bypass pipe  591 ) and a fourth valve  585 . The second bypass pipe  577  is connected between second and third connection pipe  573  and  575 . In heating mode, some of refrigerant condensed at indoor heat exchangers  410  and  410 ′ and transferred to a refrigerant heating device  600  is bypassed through the second bypass pipe  577 . That is, some of refrigerant flowing through the second connection pipe  573  is bypassed to the third connection pipe  575  through the second bypass pipe  577 . In heating mode, the fourth valve  585  is opened if the refrigerant heating device  600  is used to heat refrigerant and is closed if the refrigerant heating device  600  is not used to heat refrigerant. In addition, the fourth valve  585  is closed in cooling mode. 
         [0046]    The opened areas of a second valve  583  and the fourth valve  585  are adjusted according to the heating load of indoor area. In more detail, if the second valve  583  is less opened and the fourth valve  585  is more opened, the amount of refrigerant bypassed through the bypass pipe  577  is increased. On the other hand, if the second valve  583  is more opened and the fourth valve  585  is less opened, the amount of refrigerant bypassed through the bypass pipe  577  is decreased. 
         [0047]    Referring to  FIG. 4 , in the current embodiment, a refrigerant heating device  600  includes an auxiliary heat exchanger  610 , a heating unit  620 , a heat exchange unit  630 , a heating pipe  640 , a fluid pipe  650 , and a pump  660 . During a heat exchange cycle, refrigerant is transferred to the auxiliary heat exchanger  610 . The heating unit  620  heats a working fluid. At the heat exchange unit  630 , the refrigerant transferred to the auxiliary heat exchanger  610  exchanges heat with the working fluid heated by the heating unit  620 . The refrigerant transferred to the auxiliary heat exchanger  610  flows through the heating pipe  640 , and the working fluid heated by the heating unit  620  circulates through the fluid pipe  650 . That is, substantially at the heat exchange unit  630 , heat exchange occurs between the refrigerant flowing through the heating pipe  640  and the working fluid circulating through the fluid pipe  650 . The pump  660  forces the working fluid to circuit through the fluid pipe  650 . 
         [0048]    In the current embodiment, other elements of the air conditioning system, such as an indoor heat exchanger  410  and a linear expansion valve  420  of an indoor unit  400 , an outdoor heat exchanger  510  of an outdoor unit  500 , a compressor  520 , a linear expansion valve  530 , a parallel pipe  540 , a check valve  550 , a four-way valve  560 , first to third connection pipes  571 ,  573 , and  575 , first and second valves  581  and  583 , the bypass pipe  591 , and a third valve  593 , have similar structures as those of the air conditioning system of the first embodiment. Thus, detailed descriptions thereof will be omitted. 
         [0049]    An air conditioning system will now be described in detail with reference to the accompanying drawing according to a third embodiment. 
         [0050]      FIG. 5  is view for illustrating flows of refrigerant in an air conditioning system when the air conditioning system is operated in heating mode according to a third embodiment. In the current embodiment, similar elements as those in the first embodiment and/or the second embodiment will not be described in detail. 
         [0051]    Referring to  FIG. 5 , in the current embodiment, a refrigerant heating device  900  includes an auxiliary heat exchanger  910 , a heating unit  920 , a heat exchange unit  930 , a heating pipe  940 , a fluid pipe  950 , and a pump  960 . In addition, the refrigerant heating device  900  further includes a second bypass pipe  980  and a fourth valve  970 . The auxiliary heat exchanger  910 , the heating unit  920 , the heat exchange unit  930 , the heating pipe  940 , the fluid pipe  950 , and the pump  960  have similar structures as those in the second embodiment. 
         [0052]    The pump  960  forces a working fluid to circulate through the fluid pipe  950  so that refrigerant flowing through the heating pipe  940  can exchange heat with the working fluid at the heat exchange unit  930 . At this time, some of the working fluid is bypassed to the heating unit  920  through the second bypass pipe  980 . 
         [0053]    The fourth valve  970  is disposed at the second bypass pipe  980 . The fourth valve  970  is used to adjust heating of the refrigerant flowing through the heating pipe  940  according to the heating load of indoor areas. In more detail, the fourth valve  970  is turned on or off or the opening of the fourth valve  970  is adjusted so as to adjust the amount of working fluid bypassed through the second bypass pipe  980 . In other words, if the fourth valve  970  is turned off, the working fluid is not bypassed through the second bypass pipe  980 . If the opened area of the fourth valve  970  is increased or decreased, the amount of working fluid bypassed through the second bypass pipe  980  is increased or decreased. Therefore, at the heat exchange unit  930 , the amount of working fluid flowing through the fluid pipe  950  for changing heat with the refrigerant flowing through the heating pipe  940  can be adjusted. Accordingly, heating of the refrigerant flowing through the heating pipe  940  can be adjusted. This adjustment of the heating of the refrigerant flowing through the heating pipe  940  may be performed according to the heating load of the indoor areas. 
         [0054]    Other elements of the air conditioning system of the current embodiment, such as an indoor heat exchanger  710  and a linear expansion valve  720  of an indoor unit  700 , an outdoor heat exchanger  810  of an outdoor unit  800 , a compressor  820 , a linear expansion valve  830 , a parallel pipe  840 , a check valve  850 , a four-way valve  860 , first to third connection pipes  851 ,  873 , and  875 , first and second valves  881  and  883 , a bypass pipe  891 , and a third valve  893 , have similar structures as those of the air conditioning systems of the first and second embodiments. Thus, detailed descriptions thereof will be omitted. 
         [0055]    As described above, according to the air conditioning system of the present disclosure, if refrigerant is heated by the refrigerant heating device in heating mode, some of refrigerant compressed by the compressor is bypassed to the outdoor heat exchanger. Therefore, owing to the refrigerant bypassed to the outdoor heat exchanger, refrigerant accumulated in the outdoor heat exchanger can be re-circulated in heat exchange cycles so that the amount of refrigerant circulating in the heat exchange cycles does not become insufficient. 
         [0056]    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.