Patent Publication Number: US-11397015-B2

Title: Air conditioning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2019-0043971, filed on Apr. 15, 2019, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to an air conditioning apparatus. 
     BACKGROUND 
     Air conditioning apparatus can maintain air within a space to be a proper state according to use and purpose thereof. In some examples, an air conditioning apparatus may include a compressor, a condenser, an expansion device, and evaporator. The air conditioning apparatus may perform a refrigerant cycle including compression, condensation, expansion, and evaporation processes with refrigerant. In some cases, the air conditioning apparatus may heat or cool a predetermined space. 
     The air conditioning apparatus may be used in various places. For example, the air conditioning apparatus may be installed in a space of a home or an office. 
     In some examples, when the air conditioning apparatus performs a cooling operation, an outdoor heat-exchanger provided in an outdoor unit may serve as a condenser, and an indoor heat-exchanger provided in an indoor unit may serve as an evaporator. In some examples, when the air conditioning apparatus performs a heating operation, the indoor heat-exchanger may serve as the condenser, and the outdoor heat-exchanger may serve as the evaporator. 
     In some cases, a type and an amount of refrigerant used in the air conditioning apparatus may be limited due to environment regulations. In some cases, to reduce an amount of refrigerant used, an air conditioning system may perform cooling or heating by performing heat exchange between the refrigerant and a predetermined fluid such as water. 
     In some examples, where the air conditioning apparatus connects a refrigerant circulation circuit and a thermal medium circulation circuit to an outdoor unit, it may be easily used in a condition of simultaneously cooling and heating an indoor space. 
     In some examples, where the refrigerant circulation circuit and the heat medium circulation circuit are not configured to be connected to the switchable outdoor unit, the air conditioning apparatus may not switch the cooling and heating operations. 
     SUMMARY 
     The present disclosure describes an air conditioning apparatus that includes a switching mechanism capable of being connected to a switchable outdoor unit and an outdoor unit, which have internal configurations different from each other. The air conditioning apparatus includes a heat exchange device performing heat exchange between water and a refrigerant, which may increase a degree of freedom of installation. 
     The present disclosure also describes an air conditioning apparatus including a switching mechanism that is configured to be connected to an outdoor unit through three pipes and to be connected to the switchable outdoor unit through two pipes and that is disposed between a heat exchange device and the outdoor unit so that a heat exchange device performing heat exchange between water and a refrigerant increases a degree of freedom of installation. 
     The present disclosure further describes an air conditioning apparatus including a switching mechanism that includes a bypass pipe through which a four-way valve and a connection pipe of a refrigerant having a specific pressure to generate a high pressure or a low pressure at a specific port of the four-way valve may communicate with each other so that an internal differential pressure of the four-way valve is used when changing a cooling operation mode or a heating operation mode. 
     The present disclosure further describes an air conditioning apparatus in which an internal differential pressure may be sufficiently secured to improve operation reliability of a four-way valve in a cooling operation mode or a heating operation mode. 
     The air conditioning apparatus may include a heat exchange device that is configured to connect an outdoor unit to an indoor unit and that includes a heat exchanger configured to perform heat exchange between a refrigerant and water, thereby reducing an amount of refrigerant used to perform a cooling operation or a heating operation. 
     A switching mechanism may be configured to connect the outdoor unit to the heat exchange device. For example, the switching mechanism may be connected to both an outdoor unit and a switchable outdoor unit, which have different configurations. The heat exchange device may improve a degree of freedom of installation regardless of the type of outdoor unit. 
     In some implementations, the switching mechanism may include a plurality of connection pipes through which refrigerants having different pressures flow and a bypass pipe configured to connect the plurality of connection pipes to each other to generate a high pressure or a low pressure in a specific port of a four-way valve, thereby easily and quickly switching a cooling or heating operation. 
     According to one aspect of the subject matter described in this application, an air conditioning apparatus includes: an outdoor unit configured to circulate refrigerant, the outdoor unit including a compressor and an outdoor heat exchanger; an indoor unit configured to circulate water; a first heat exchanger and a second heat exchanger that are configured to perform heat exchange between the refrigerant and the water; a first four-way valve disposed at one side of the first heat exchanger and configured to adjust a flow direction of the refrigerant in the first heat exchanger; a second four-way valve disposed at one side of second heat exchanger and configured to adjust a flow direction of the refrigerant the second heat exchanger; a first connection pipe connected to the outdoor unit and to a first port of the first four-way valve; a second connection pipe connected to a second port of the first four-way valve and to the first heat exchanger; a third connection pipe connected to a third port of the first four-way valve; a fourth connection pipe connected to the first heat exchanger; a first expansion valve installed at the fourth connection pipe; at least one bypass pipe configured to connect two connection pipes among the first connection pipe, the third connection pipe, and the fourth connection pipe to each other, in which the at least one bypass pipe is configured to guide the refrigerant between the two connection pipes; and at least one bypass valve installed at the at least one bypass pipe. 
     Implementations according to this aspect may include one or more of the following features. For example, the at least one bypass pipe may include a first bypass pipe connected to a first bypass branch part disposed at the first connection pipe and to a second bypass branch part disposed at the third connection pipe. In some examples, the at least one bypass valve may include a first bypass valve installed at the first bypass pipe. In some examples, the at least one bypass pipe may further include a second bypass pipe connected to a third bypass branch part disposed at the first connection pipe and to a fourth bypass branch part disposed at the fourth connection pipe. 
     In some implementations, the at least one bypass valve may include a first bypass valve installed at the first bypass pipe and a second bypass valve installed at the second bypass pipe. In some examples, the at least one bypass pipe may further include a third bypass pipe connected to a fifth bypass branch part disposed at the third connection pipe and to a sixth bypass branch part disposed at the fourth connection pipe. In some examples, the at least one bypass valve may include a third bypass valve installed at the third bypass pipe. 
     In some implementations, the air conditioning apparatus may further include a first check valve installed at the first bypass pipe, a second check valve installed at the second bypass pipe, and a third check valve installed at the third bypass pipe. In some examples, the third check valve may be installed at a point between the second bypass branch part and the fifth bypass branch part. 
     In some implementations, the air conditioning apparatus may further include: a first branch part disposed at the first connection pipe; and a fifth connection pipe connected to the first branch part and to a first port of the second four-way valve. In some examples, the air conditioning apparatus may further include: a sixth connection pipe connected to a second port of the second four-way valve and to the second heat exchanger. 
     In some implementations, the air conditioning apparatus may further include: a second branch part disposed at the third connection pipe; a third branch part disposed at the fourth connection pipe; a seventh connection pipe connected to the second heat exchanger and to the third branch part; and a second expansion valve installed at the seventh connection pipe. In some implementations, the air conditioning apparatus may further include: an eighth connection pipe connected to the second branch part and to a third port of the second four-way valve. 
     In some implementations, the air conditioning apparatus may further include: a first outdoor unit connection pipe disposed in the outdoor unit and connected to the first connection pipe; a second outdoor unit connection pipe disposed in the outdoor unit and connected to the third connection pipe; and a third outdoor unit connection pipe disposed in the outdoor unit and connected to the fourth connection pipe. In some implementations, the air conditioning apparatus may further include: a first outdoor unit connection pipe connected to the outdoor unit and to the third connection pipe; and a second outdoor unit connection pipe connected to the outdoor unit and to the fourth connection pipe. 
     In some implementations, the indoor unit may include: a first indoor unit connected to the first heat exchanger; and a second indoor unit connected to the second heat exchanger. 
     According to another aspect, an air conditioning apparatus includes: an outdoor unit configured to circulate refrigerant; an indoor unit configured to circulate water; a first heat exchanger and a second heat exchanger that are configured to perform heat exchange between the refrigerant and the water, each of the first heat exchanger and the second heat exchanger being fluidly connected to the outdoor unit and the indoor unit; a first four-way valve disposed at one side of the first heat exchanger and configured to adjust a flow direction of the refrigerant in the first heat exchanger; a second four-way valve disposed at one side of second heat exchanger and configured to adjust a flow direction of the refrigerant in the second heat exchanger; a first connection pipe connected to the outdoor unit and to a first port of the first four-way valve; a second connection pipe connected to a second port of the first four-way valve and to the first heat exchanger; a third connection pipe connected to a third port of the first four-way valve; a first bypass pipe connected to a first bypass branch part disposed at the first connection pipe and to a second bypass branch part disposed at the third connection pipe; and a first bypass valve installed at the first bypass pipe. 
     Implementations according to this aspect may include one or more of the following features. For example, the air conditioning apparatus may further include: a fourth connection pipe connected to the first heat exchanger; a first expansion valve installed at the fourth connection pipe; a second bypass pipe connected to a third bypass branch part disposed at the first connection pipe and to a fourth bypass branch part disposed at the fourth connection pipe; and a second bypass valve installed at the second bypass pipe. 
     In some implementations, the air conditioning apparatus may further include: a third bypass pipe connected to a fifth bypass branch part disposed at the third connection pipe and to a sixth bypass branch part disposed at the fourth connection pipe; and a third bypass valve installed at the third bypass pipe. In some implementations, the air conditioning apparatus may further include: a fifth connection pipe connected to a first branch part disposed at the first connection pipe and to a first port of the second four-way valve; a sixth connection pipe connected to a second port of the second four-way valve and to the second heat exchanger; a seventh connection pipe connected to the second heat exchanger and to a third branch part disposed at the fourth connection pipe; and a second expansion valve installed at the seventh connection pipe. 
     The details of one or more implementations 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 
         FIG. 1  is a schematic view illustrating an example configuration of an air conditioning apparatus. 
         FIG. 2  is a cycle diagram illustrating an example configuration of a heat exchange device and a switching mechanism. 
         FIG. 3  is a cycle diagram illustrating an example of a flow of refrigerant in the heat exchange device and the switching mechanism during a simultaneous operation of the air conditioning apparatus. 
         FIG. 4  is a schematic view illustrating an example configuration of an air conditioning apparatus. 
         FIG. 5  is a cycle diagram illustrating an example configuration of a heat exchange device and a switching mechanism. 
         FIG. 6  is a cycle diagram illustrating an example of a flow of refrigerant in the heat exchange device and the switching mechanism during a cooling operation mode of the air conditioning apparatus. 
         FIG. 7  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during a heating operation switching mode of the air conditioning apparatus. 
         FIG. 8  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during a heating operation mode of the air conditioning apparatus. 
         FIG. 9  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during a cooling operation switching mode of the air conditioning apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary implementations will be described with reference to the accompanying drawings. The disclosure may, however, be implemented in many different forms and should not be construed as being limited to the implementations set forth herein; rather, that alternate implementations included in other retrogressive disclosures or falling within the spirit and scope of the present disclosure will fully convey the concept of the disclosure to those skilled in the art. 
       FIG. 1  is a schematic view illustrating an example configuration of an air conditioning apparatus. 
     Referring to  FIG. 1 , an air conditioning apparatus  1  includes an outdoor unit  10 , an indoor unit  50 , a switching mechanism  200  connected to the outdoor unit  10 , and a heat exchange device  100  connected to the switching mechanism  200 . The switching mechanism  200  may be provided between the outdoor unit  10  and the heat exchange device  100 . 
     The switching mechanism  200  is provided so that the heat exchange device  100  is connected to a cooling/heating switching outdoor unit or a simultaneous cooling/heating outdoor unit. The switching mechanism  200  may be provided as a separate kit that is detachable to the outdoor unit or may be integrated with the outdoor unit. 
     In some implementations, the outdoor unit  10  may be provided as the simultaneous cooling/heating outdoor unit. For example, the outdoor unit  10  may be one device that can perform both of a cooling operation and a heating operation simultaneously or selectively. In some cases, the outdoor unit  10  may be provided as separate a cooling outdoor unit and a heating outdoor unit. 
     The outdoor unit  10 , the switching mechanism  200 , and the heat exchange device  100  may be fluidly connected to each other by a first fluid. For example, the first fluid may include a refrigerant. The refrigerant may be configured to flow through a refrigerant-side flow path of a heat exchanger provided in the heat exchange device  100 , the switching mechanism  200 , and the outdoor unit  10 . 
     The outdoor unit  10  may include a compressor  11  and an outdoor heat exchanger  15 . An outdoor fan  16  may be provided at one side of the outdoor heat exchanger  15  to blow external air toward the outdoor heat exchanger  15  so that heat exchange between the external air and the refrigerant of the outdoor heat exchanger  15  is performed. Also, the outdoor unit  10  may further include a main expansion valve  18  (EEV). 
     The air conditioning apparatus  1  may further include three pipes  20 ,  25 , and  27  connecting the outdoor unit  10  to the switching mechanism  200 . The three pipes  20 ,  25 , and  27  include a first outdoor unit connection pipe  20  as a “high-pressure pipe” through which a high-pressure gas refrigerant flows, a second outdoor unit as a “low-pressure pipe” through which a low-pressure gas refrigerant flows, and a third outdoor unit connection pipe  27  as a “liquid pipe” through which a liquid refrigerant flows. That is, the outdoor unit  10  and the switching mechanism  200  may have a “three pipe connection structure”, and the refrigerant may circulate through the outdoor unit  10  and the heat exchange device  100  via the three pipes  20 ,  25 , and  27 . 
     The heat exchange device  100  and the indoor unit  50  may be fluidly connected by a second fluid. For example, the second fluid may include water. The water may flow through a water-side flow path of a heat exchanger provided in the heat exchange device  100  and the indoor unit  50 . 
     That is, the heat exchanger includes the refrigerant-side flow path and the water-side flow path. For example, the heat exchanger may include a plate-type heat exchanger in which the water and the refrigerant are heat-exchanged with each other. 
     The indoor unit  50  may include a plurality of indoor units  60  and  70 . The plurality of indoor units  60  and  70  include a first indoor unit  60  and a second indoor unit  70 . Although two indoor units are connected to the heat exchange device  100  in  FIG. 1 , the implementation is not limited thereto. For example, three or more indoor units may be connected to the heat exchange device  100 . 
     The air conditioning apparatus  1  may further include pipes  30  and  35  connecting the heat exchange device  100   a  to the indoor unit  50 . The pipes  30  and  35  include a first indoor unit connection pipe  30  connecting the heat exchange device  100   a  to the first indoor unit  60  and a second indoor unit connection pipe  35  connecting the heat exchange device  100   a  to the second indoor unit  70 . 
     The water may circulate through the heat exchange device  100   a  and the indoor unit  50  via the first and second indoor unit connection pipes  30  and  35 . As the number of indoor units increases, the number of pipes connecting the heat exchange device  100   a  to the indoor units may also increase. 
     In some implementations, the refrigerant circulating through the outdoor unit  10 , the switching mechanism  200 , and the heat exchange device  100  and the water circulating through the heat exchange device  100  and the indoor unit  50  may be heat-exchanged with each other through the heat exchangers  110  and  115  (see  FIG. 2 ) provided in the heat exchange device  100 . Water cooled or heated through the heat exchange may be heat-exchanged with an indoor heat exchangers  61  and  71  (see  FIG. 2 ) provided in the indoor unit  50  to perform cooling or heating in an indoor space. 
       FIG. 2  is a cycle diagram illustrating an example configuration of the heat exchange device and the switching mechanism. 
     Referring to  FIG. 2 , the switching mechanism  200  includes a first connection pipe  131  connected to a first outdoor unit connection pipe  20  through a first service valve  21 . The first connection pipe  131  may extend into the heat exchange device  100  and may be connected to a first port  120   a  of the first four-way valve  120 . 
     The switching mechanism  200  further includes a third connection pipe  133  connected to a second outdoor unit connection pipe  25  through a second service valve  26 . The third connection pipe  133  may extend into the heat exchange device  100  and may be connected to a third port  120   c  of the first four-way valve  120 . 
     The switching mechanism  200  further includes a fourth connection pipe  134  connected to a third outdoor unit connection pipe  27  through a third service valve  28 . The fourth connection pipe  134  may extend into the heat exchange device  100  and may be connected to the first heat exchanger  110 . 
     The first to third outdoor unit connection pipes  20 ,  25 , and  27  may be connected to the switching mechanism  200  through the first to third service valves  21 ,  26 , and  28 , and thus, the outdoor unit  10  and the switching mechanism  200  may be connected to each other through the “three pipes”. 
     The heat exchange device  100  may include heat exchangers  110  and  115 , a refrigerant pipe, and a water pipe, and a plurality of valves, and a pump. 
     In detail, the heat exchange device  100  includes a first heat exchanger  110  fluidly connected to the first indoor unit  60  and a second heat exchanger  115  fluidly connected to the second indoor unit  70 . 
     The first heat exchanger  110  and the second heat exchanger  115  may have the same configuration. The first and second heat exchangers  110  and  115  may include a plate-type heat exchanger and be configured so that the water flow path and the refrigerant flow path are alternately stacked with each other. 
     The first heat exchanger  110  includes a first refrigerant flow path  111  and a first water flow path  112 . One side of the first refrigerant flow path  111  may be connected to the second connection pipe  132 . The second connection pipe  132  may extend from a second port  120   b  of the first four-way valve  120  to be connected to the first heat exchanger  110 . 
     The other side of the first refrigerant flow path  111  may be connected to the fourth connection pipe  134 . The fourth connection pipe  134  may extend from the third service valve  28  and be connected to the first heat exchanger  110 . That is, both sides of the first refrigerant flow path  111  may be connected to the second connection pipe  132  and the fourth connection pipe  134 , respectively. 
     A refrigerant discharged from the outdoor unit  10  may be introduced into the first refrigerant flow path  111  through the first connection pipe  131  and the first four-way valve  120 , and a refrigerant passing through the first refrigerant flow path  111  may be introduced into the outdoor unit  10  through the fourth connection pipe  134 . 
     The first water flow path  112  may be fluidly connected to the first indoor unit  60 . Thus, the water discharged from the first indoor unit  60  may be 1 introduced into the first water flow path  112 , or the water passing through the first water flow path  112  may be introduced into the first indoor unit  60 . 
     The heat exchange device  100  includes a first heat exchanger outlet pipe  171  and a first heat exchanger inlet pipe  172 , which are connected to the first water flow path  112  of the first heat exchanger  110 . In addition, the first indoor unit connection pipe  30  includes a first indoor unit inlet pipe  31  and a first indoor unit outlet pipe  32 . 
     The first heat exchanger outlet pipe  171  may be connected to the first indoor unit inlet pipe  31 . Therefore, the water discharged from the first water flow path  112  of the first heat exchanger  110  may be introduced into the first indoor unit  60  through the first heat exchanger outlet pipe  171  and the first indoor unit inlet pipe  31 . 
     The first indoor unit  60  includes a first indoor heat exchanger  61  and a first indoor fan  65 . The first indoor fan  65  is disposed adjacent to the first indoor heat exchanger  61  to blow indoor air so that heat exchange occurs between water passing through the first indoor heat exchanger  61  with the indoor air. 
     The first indoor unit inlet pipe  31  may be connected to an inlet-side of the first indoor heat exchanger  61 . Also, the first indoor unit outlet pipe  32  may be connected to an outlet-side of the first indoor heat exchanger  61 . 
     The first heat exchanger inlet pipe  172  may be provided with a first pump  173  for forcing a flow of water. When the first pump  173  is driven, water may circulate through a water-side flow path connecting the first indoor unit  60  to the first heat exchanger  110 , i.e., the first indoor heat exchanger  61 , the first indoor unit outlet pipe  32 , the first heat exchanger inlet pipe  172 , the first water flow path  112 , the first heat exchanger outlet pipe  171 , and the first indoor unit inlet pipe  31 . 
     Although the first pump  173  is illustrated as being installed in the first heat exchanger inlet pipe  172  in  FIG. 2 , the first pump  173  may be installed in the first heat exchanger outlet pipe  171 . The second heat exchanger  115  includes a second refrigerant flow path  116  and a second water flow path  118 . One side of the second refrigerant flow path  116  may be connected to a sixth connection pipe  136 . The sixth connection pipe  136  may extend from a second port  125   b  of a second four-way valve  125  to be connected to the second heat exchanger  115 . 
     The other side of the second refrigerant flow path  116  may be connected to a seventh connection pipe  137 . The seventh connection pipe  137  may extend from a third branch part  134   a  of a fourth connection pipe  134  and may be connected to the second heat exchanger  115 . That is, both sides of the second refrigerant flow path  116  may be connected to the sixth connection pipe  136  and the seventh connection pipe  137 . 
     The refrigerant flowing through the fourth connection pipe  134  may be branched from a third branch part  134   a  to flow through the seventh connection pipe  137  and may be introduced into the second refrigerant flow path  116 . Also, the refrigerant flowing through the second refrigerant flow path  116  may be introduced into the second port  125   b  of the second four-way valve  125  via the sixth connection pipe  136  and then be discharged through the third port  125   c.    
     The second water flow path  118  may be fluidly connected to the second indoor unit  70 , and the refrigerant discharged from the second indoor unit  70  may be introduced into the second water flow path  118 , or the refrigerant passing through the second water flow path  118  may be introduced into the second indoor unit  70 . 
     The heat exchange device  100  includes a second heat exchanger outlet pipe  174  and a second heat exchanger inlet pipe  175 , which are connected to the second water flow path  118  of the second heat exchanger  115 . Also, the second indoor unit connection pipe  35  includes a second indoor unit inlet pipe  36  and a second indoor unit outlet pipe  37 . 
     The second heat exchanger outlet pipe  174  may be connected to the second indoor unit inlet pipe  36 . Therefore, the water discharged from the second water flow path  118  of the second heat exchanger  115  may be introduced into the second indoor unit  70  through the second heat exchanger outlet pipe  174  and the second indoor unit inlet pipe  36 . 
     The second indoor unit  70  includes a second indoor heat exchanger  71  and a second indoor fan  75 . The second indoor fan  75  is disposed adjacent to the second indoor heat exchanger  71  to blow indoor air so that heat exchange occurs between the water passing through the second indoor heat exchanger  71  with the indoor air. 
     The second indoor unit inlet pipe  36  may be connected to an inlet-side of the second indoor heat exchanger  71 . Also, the second indoor unit outlet pipe  37  may be connected to an outlet-side of the second indoor heat exchanger  71 . 
     The second heat exchanger inlet pipe  175  may be provided with a second pump  176  for forcing a flow of water. When the second pump  176  is driven, the water may circulate through the water-side flow path connecting the second indoor unit  70  to the second heat exchanger  115 , i.e., through the second indoor heat exchanger  71 , the second indoor unit outlet pipe  37 , the second heat exchanger inlet pipe  175 , the second water flow path  118 , the second heat exchanger outlet pipe  174 , and the second indoor unit inlet pipe  36 . 
     Although the second pump  176  is illustrated as being installed in the second heat exchanger inlet pipe  175  in  FIG. 2 , the implementation is not limited thereto. For example, the second pump  176  may be installed in the second heat exchanger outlet pipe  174 . 
     A first branch part  131   a  is disposed on the first connection pipe  131 . Also, the heat exchange device  100  further includes a fifth connection pipe  135  connected to the first branch part  131   a  to extend to the second four-way valve  125 . The fifth connection pipe  135  may be connected to the first port  125   a  of the second four-way valve  125 . 
     In some examples, the first branch part  131   a  may be a portion of the first connection pipe  131 . In some examples, the first branch part  131   a  may be a separate part such as a multi-way connection pipe. 
     A second branch part  133   a  is disposed on the third connection pipe  133 . Also, the heat exchange device  100  further includes an eighth connection pipe  138  connected to the second branch part  133   a  to extend to the second four-way valve  125 . The eighth connection pipe  138  may be connected to the third port  125   c  of the second four-way valve  125 . 
     In some examples, the second branch part  133   a  may be a portion of the first connection pipe  133 . In some examples, the second branch part  133   a  may be a separate part such as a multi-way connection pipe. 
     The heat exchange device  100  includes the first four-way valve  120  and the second four-way valve  125 , which control a flow direction of the refrigerant. 
     The first four-way valve  120  includes the first port  120   a  to which the first connection pipe  131  is connected, the second port  120   b  to which the second connection pipe  132  is connected, and the third port  120   c  to which the third connection pipe  133  is connected. A fourth port of the first four-way valve  120  may be closed. 
     The second four-way valve  125  includes a first port  125   a  to which the fifth connection pipe  135  is connected, a second port  125   b  to which the sixth connection pipe  136  is connected, and a third port  125   c  to which the eighth connection pipe  138  is connected. 
     The heat exchange device  100  may further include expansion valves  140  and  145  for decompressing the refrigerant. Each of the expansion valves  140  and  145  may include an electronic expansion valve (EEV). 
     The EEV may adjust a degree of opening thereof to allow a pressure of the refrigerant passing through the expansion valve to drop down. For example, when the expansion valve is fully opened, the refrigerant may pass through the expansion valve without dropping down, and when the degree of opening of the expansion valve decreases, the refrigerant may be decompressed. A degree of decompression of the refrigerant may increase as the degree of opening decreases. 
     In detail, the expansion valves  140  and  145  may include a first expansion valve  140  installed in the fourth connection pipe  134 . The first expansion valve  140  may be installed at one point of the fourth connection pipe  134  between the third branch part  134   a  and an end thereof connected to the first refrigerant flow path  111 . 
     For example, during the simultaneous operation of the air conditioning apparatus  1 , a high-pressure gas refrigerant introduced through the first outdoor unit connection pipe  20  may be introduced into the first refrigerant flow path  111  of the first heat exchanger  110  and then be condensed. Also, the heating operation may be performed in the first indoor unit  60  connected to the first heat exchanger  110 . 
     A liquid refrigerant discharged from the first refrigerant flow path  111  may not be decompressed while passing through the first expansion valve  140 . A portion of the refrigerant passing through the first expansion valve  140  may be discharged to the third outdoor unit connection pipe  27  through the third service valve  28 . Also, the remaining portion of the refrigerant may introduced into the seventh connection pipe  137  from the third branch part  134   a.    
     The expansion valves  140  and  145  may further include a second expansion valve  145  installed in the seventh connection pipe  137 . 
     For example, during the simultaneous operation of the air conditioning apparatus  1 , the refrigerant passing through the first expansion valve  140 , branched from the third branch part  134   a , and introduced into the seventh connection pipe  137  may be decompressed into a low-pressure refrigerant while passing through the second expansion valve  145  and then be introduced into the second refrigerant flow path  116  of the second heat exchanger  115  so as to be evaporated. Also, in the second indoor unit  70  connected to the second heat exchanger  150 , cooling is performed. 
     The low-pressure gas refrigerant discharged from the second refrigerant flow path  116  may be discharged to the second outdoor unit connection pipe  25  via the sixth connection pipe  136 , the second four-way valve  125 , the eighth connection pipe  138 , and the third connection pipe  133 . 
     The switching mechanism  200  may include a first bypass pipe  210  connecting the first connection pipe  131  to the third connection pipe  133 . One end of the first bypass pipe  210  may be connected to a first bypass branch part  131   b  of the first connection pipe  131 , and the other end thereof may be connected to a second bypass part of the third connection pipe  133 . 
     The first branch part  131   a  may be disposed at one point between the first bypass branch part  131   b  and the first port  120   a  of the first four-way valve  120  with respect to the first connection pipe  131 . 
     The second branch part  133   a  may be disposed at one point between the second bypass branch part  133   b  and the third port  120   c  of the first four-way valve  120  with respect to the third connection pipe  133 . 
     The first bypass pipe  210  is provided with a first bypass valve  241  for controlling an opening and closing of the pipe. For example, the first bypass valve  241  may include a two-way valve or a solenoid valve having a relatively low pressure loss. 
     A first check valve  251  may be installed in the first bypass pipe  210 . The first check valve  251  may allow a flow of the refrigerant from the second bypass branch part  133   b  to the first bypass branch part  131   b  and may restrict a flow of the refrigerant flow in the opposite direction. 
     The switching mechanism  200  may include a second bypass pipe  220  connecting the first connection pipe  131  to the fourth connection pipe  134 . One end of the second bypass pipe  220  may be connected to a third bypass branch part  131   c  of the first connection pipe  131 , and the other end thereof may be connected to a fourth bypass branch part  134   b  of the fourth connection pipe  134 . 
     The third bypass branch part  131   c  may be disposed at one point between the first bypass branch part  131   b  and the first branch part  131   a  with respect to the first connection pipe  131 . 
     The third branch part  134   a  may be disposed at one point between the fourth bypass branch part  134   b  and the fourth connection pipe  134  connected to the first refrigerant flow path  111  with respect to the fourth connection pipe  134 . 
     The second bypass pipe  220  is provided with a second bypass valve  243  for controlling an opening and closing of the pipe. For example, the second bypass valve  243  may include a two-way valve or a solenoid valve having a relatively low pressure loss. 
     A second check valve  253  may be installed in the second bypass pipe  220 . The second check valve  253  may allow the refrigerant to flow from the fourth bypass branch part  134   b  to the third bypass branch part  131   c  and may restrict a flow of the refrigerant in the opposite direction. 
     The switching mechanism  200  may include a third bypass pipe  230  connecting the third connection pipe  133  to the fourth connection pipe  134 . One end of the third bypass pipe  230  may be connected to a fifth bypass branch part  133   c  of the third connection pipe  133 , and the other end thereof may be connected to a sixth bypass branch part  134   c  of the fourth connection pipe  134 . 
     The fifth bypass branch part  133   c  may be disposed at one point between the second bypass branch part  133   b  and the second branch part  133   a  with respect to the third connection pipe  133 . 
     The sixth bypass branch part  134   c  may be disposed at one point between the fourth bypass branch part  134   b  and the third branch part  134   a  with respect to the fourth connection pipe  134 . 
     The third bypass pipe  230  is provided with a third bypass valve  245  for controlling an opening and closing of the pipe. For example, the third bypass valve  245  may include a two-way valve or a solenoid valve having a relatively low pressure loss. 
     A third check valve  255  may be installed in the third bypass pipe  230 . The third check valve  255  may allow the refrigerant to flow from the fifth bypass branch part  133   c  to the sixth bypass branch part  134   c  and may restrict a flow of the refrigerant in the opposite direction. 
     The third connection pipe  133  may be provided with a fourth check valve  257  for controlling one-way flow of the refrigerant. The fourth check valve  257  may be installed at one point of the third connection pipe  133  between the second bypass branch part  133   b  and the fifth bypass branch part  133   c . The fourth check valve  257  may allow the refrigerant flow from the fifth bypass branch part  133   c  to the second bypass branch part  133   b  and may restrict a flow of the refrigerant flow in the opposite direction. 
       FIG. 3  is a cycle diagram illustrating an example of a flow of a refrigerant in the heat exchange device and the switching mechanism during the simultaneous operation of the air conditioning apparatus. Referring to  FIG. 3 , a description will be given of a refrigerant flow during the simultaneous operation in which the cooling/heating of the air conditioning apparatus  1  are performed together. 
     Referring to  FIG. 3 , when the simultaneous operation is performed in the air conditioning apparatus  1 , the high-pressure gas refrigerant compressed by the compressor  11  of the outdoor unit  10  flows to the first connection pipe  131  through the first outdoor unit connection pipe  20  and then be introduced into the first four-way valve  120  through the first port  120   a.    
     The refrigerant may be discharged from the first four-way valve  120  through the second port  120   b  and may be introduced into the first refrigerant flow path  111  of the first heat exchanger  110  so as to be condensed. In the process of condensing the refrigerant in the first heat exchanger  110 , water flowing through a first water flow path  112  of the first heat exchanger  110  may be heated, and the heated water may be supplied to the first indoor unit  60  to perform the heating. 
     The refrigerant discharged from the first heat exchanger  110  may be introduced into the fourth connection pipe  134  to pass through the first expansion valve  140 . Here, since the first expansion valve  140  is completely opened, the refrigerant passing through the first expansion valve  140  may not be decompressed. 
     A portion of the refrigerant passing through the first expansion valve  140  may be introduced into the outdoor unit  10  through the third outdoor unit connection pipe  27  and then may be decompressed by the main expansion valve  18 , evaporated in the outdoor heat exchanger  15 , and suctioned into the compressor  11 . 
     Then, the remaining refrigerant of the refrigerant passing through the first expansion valve  140  may be introduced into the seventh connection pipe  137  from the third branch part  134   a  and may be decompressed by the second expansion valve  145 . Also, the decompressed refrigerant may be introduced into the second refrigerant flow path  116  of the second heat exchanger  115  so as to be evaporated. During the evaporation of the refrigerant, water flowing through the second water flow path  118  of the second heat exchanger  115  may be cooled, and the cooled water may be supplied to the second indoor unit  70  to perform the cooling. 
     The refrigerant discharged from the second heat exchanger  115  may be introduced into the second four-way valve  125  through the second port  125   b  and may be discharged from the second four-way valve  125  through the third port  125   c . Also, the refrigerant may be introduced into the third connection pipe  133  from the second branch part  133   a  to flow to the outdoor unit  10  via the second outdoor unit connection pipe  25 . Also, the refrigerant introduced into the outdoor unit  10  may be suctioned into the compressor  11 . 
     On the other hand, since the third port  120   c  of the first four-way valve  120  is closed, the refrigerant may be prevented from being introduced into the first four-way valve  120  from the second branch part  133   a . Also, since the first to third bypass valves  241 ,  243 , and  245  are all closed, the refrigerant may be prevented to flowing in the first to third bypass pipes  210 ,  220 , and  230 . 
     Due to the circulation of the refrigerant and the water, the heating operation in the first indoor unit  60  and the cooling operation in the second indoor unit  70  may be performed together. 
     Hereinafter, a description will be made. Since the forgoing implementation are the same as another implementation except for only portions of the constitutions, different points therebetween will be described principally, and descriptions of the same parts will be denoted by the same reference numerals and descriptions of the foregoing implementation. 
       FIG. 4  is a schematic view illustrating an example configuration of an air conditioning apparatus, and  FIG. 5  is a cycle diagram illustrating an example configuration of a heat exchange device and a switching mechanism. 
     Referring to  FIGS. 4 and 5 , an air conditioning apparatus  1   a  includes an outdoor unit  10   a , an indoor unit  50 , a switching mechanism  200  connected to the outdoor unit  10 , and a heat exchange device  100  connected to the switching mechanism  200 . The switching mechanism  200  may be provided between the outdoor unit  10  and the heat exchange device  100 . 
     The switching mechanism  200  is provided so that the heat exchange device  100  is connected to a cooling/heating switching outdoor unit or a simultaneous cooling/heating outdoor unit. The switching mechanism  200  may be provided as a separate kit that is detachable to the outdoor unit or may be integrated with the outdoor unit. 
     Since the internal configurations of the heat exchange device  100  and the switching mechanism  200  are the same as those of the heat exchange device and the switching mechanism described according to the foregoing implementation, detailed descriptions will be omitted below, and the description of the foregoing implementation will be derived as it is. 
     The outdoor unit  10   a  according to this implementation may be configured as a cooling/heating switching outdoor unit. 
     The outdoor unit  10   a  may include a compressor  11 , an outdoor heat exchanger  15 , an outdoor fan  16 , and a main expansion valve  18  (EEV). The above-described parts will be quoted from the descriptions of the foregoing implementation. The air conditioning apparatus  1   a  further includes two pipes  25   a  and  27   a  connecting the outdoor unit  10   a  to the heat exchange device  100 . The two pipes  25   a  and  27   a  include a first outdoor unit connection pipe  25   a  as a gas pipe through which a gas refrigerant flows and a second outdoor unit connection pipe  27   a  as a liquid pipe through which a liquid refrigerant flows. 
     That is, the outdoor unit  10   a  and the switching mechanism  200  may have a “two pipe connection structure”, and thus, the refrigerant may circulate through the outdoor unit  10   a , the heat exchange device  100 , and the switching mechanism  200  via the two pipes  25   a  and  27   a.    
     The heat exchange device  100  and the indoor unit  50  may be fluidly connected to each other by water. The water may flow through a water-side flow path of a heat exchanger provided in the heat exchange device  100  and the indoor unit  50 . The heat exchanger may include a plate-type heat exchanger. In some examples, the indoor unit  50  may include a first indoor unit  60  and a second indoor unit  70 . Description of the connection structure between the heat exchange device  100  and the indoor unit  50  will be derived from the description according to the foregoing implementation. 
     A first service valve  21  may be closed by the “two pipe connection structure”. That is, when the cooling/heating switchable outdoor unit  10   a  is installed, the outdoor unit  10   a  and the switching mechanism  200  may be connected to the first and second outdoor unit connection pipes  25   a  and  27   a  through second and third service valves  26  and  28 , respectively. As described above, the internal configurations of the switching mechanism  200  and the heat exchange device  100  are the same as the internal configurations of the switching mechanism and the heat exchanger described according to the foregoing implementation. 
     Therefore, according to the installation condition of the air conditioning apparatus, even if any outdoor unit among the simultaneous outdoor unit  10  and the switchable outdoor unit  10   a  is installed, the outdoor unit, the switching mechanism, and the heat exchange device  100  may be connected to each other through the selective connection of the outdoor unit connection pipe and the service valve. 
     Hereinafter, a flow of a separate refrigerant for each operation mode will be described with reference to the configuration of the air conditioning apparatus  1   a  in which the switchable outdoor unit  10   a , the switching mechanism  200 , and the heat exchange device  100  are connected to each other. 
       FIG. 6  is a cycle diagram illustrating an example of a flow of a refrigerant in the heat exchange device and the switching mechanism during the cooling operation mode of the air conditioning apparatus. 
     Referring to  FIG. 6 , when the “cooling operation mode” of the air conditioning apparatus  1   a  is performed, a liquid refrigerant condensed in the outdoor heat exchanger  15  of the outdoor unit  10   a  may be introduced into a fourth connection pipe  134  through a second outdoor unit connection pipe  27   a , and a portion of the refrigerant may be branched from a third branch part  134   a  and be introduced into a seventh connection pipe  137 . 
     The refrigerant of the fourth connection pipe  134  may be decompressed in a first expansion valve  140  and be introduced into a first refrigerant flow path  111  of a first heat exchanger  110  and then be heat-exchanged with a first water flow path  112 . Dur to the heat exchange, the refrigerant of the first refrigerant flow path  111  may be evaporated, and the water of the first water flow path  112  may be cooled. The cooled water may be introduced into the first indoor unit  60  to perform cooling. 
     The refrigerant of the seventh connection pipe  137  may be decompressed in a second expansion valve  145  and be introduced into a second refrigerant flow path  116  of a second heat exchanger  115  and then be heat-exchanged with a second water flow path  118 . Dur to the heat exchange, the refrigerant of the second refrigerant flow path  116  may be evaporated, and the water of the second water flow path  118  may be cooled. The cooled water may be introduced into the second indoor unit  70  to perform cooling. 
     The refrigerant discharged from the first heat exchanger  110  may be introduced into a first four-way valve  120  through a second port  120   b  and may be discharged through a third port  120   c . The refrigerant discharged from the first four-way valve  120  may be introduced into a third connection pipe  133  and may be introduced into the outdoor unit  10   a  through a first outdoor unit connection pipe  25   a.    
     The refrigerant discharged from the second heat exchanger  115  may be introduced into a second four-way valve  125  through a second port  125   b  and may be discharged through a third port  125   c . The refrigerant discharged from the second four-way valve  125  may be introduced into an eighth connection pipe  138  and may be introduced into a third connection pipe  133  from a second branch part  133   a . Also, the refrigerant may be introduced into the outdoor unit  10   a  through the first outdoor unit connection pipe  25   a.    
     The refrigerant introduced into the outdoor unit  10   a  may be suctioned into the compressor  11 . Since first to third bypass valves  241 ,  243  and  245  are all closed during the cooling operation, a flow of the refrigerant through the first to third bypass pipes  210 ,  220 , and  230  may be restricted. This refrigerant cycle may circulate. 
       FIG. 7  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during a heating operation switching mode of the air conditioning apparatus. 
     While the cooling operation of the air conditioning apparatus  1   a  is performed as shown in  FIG. 6 , when a switching signal for the heating operation is inputted to the air conditioning apparatus  1   a , a “heating operation switching mode” may be performed. 
     In a state in which second ports  120   b  and  125   b  and third ports  120   c  and  125   c  are opened, and first ports  120   a  and  125   a  are closed in first and second four-way valves  120  and  125  according to the cooling operation, when the heating operation is performed, the switching ports of the first and second four-way valves  120  and  125  may be changed. 
     To allow the switching operation of the first and second four-way valves  120  and  125  to be easily performed, an internal differential pressure between the first and second four-way valves  120  and  125  may need to be equal to or greater than a set pressure. For example, the set pressure may be about 350 kpa. 
     To allow the internal differential pressure between the first and second four-way valves  120  and  125  to be equal to or greater than the set pressure, a “heating operation switching mode” may be performed at an initial time at which the heating operation is performed. 
     When the heating operation switching mode is performed, the refrigerant compressed by the compressor  11  of the outdoor unit  10   a  may be introduced into the third connection pipe  133  through the first outdoor unit connection pipe  25   a . Here, since the first bypass valve  241  is opened, the refrigerant may be introduced into a first bypass pipe  210  from a second bypass branch part  133   b . Also, the refrigerant may be prevented from flowing from a second bypass branch part  133   b  to a fifth bypass branch part  133   c  by a fourth check valve  257 . 
     The refrigerant of the first bypass pipe  210  is introduced into a first connection pipe  131  from a first bypass branch part  131   b  and is introduced into the first four-way valve  120  through the first port  120   a . A portion of the refrigerant of the first connection pipe  131  may be introduced from the first branch part  131   a  to the fifth connection pipe  135  and be introduced into the second four-way valve  125  through the first port  125   a.    
     The refrigerant introduced into the first four-way valve  120  may be discharged through the second port  120   b  and introduced into the first heat exchanger  110 , and the refrigerant introduced into the second four-way valve  125  may be discharged through the second port and be introduced into the second heat exchanger  115  through the second port  125   b . That is, each of the first ports  120   a  and  125   a  and each of the second ports  120   b  and  125   b  of the first and second four-way valves  120  and  125  may be opened to generate a high pressure, and the third ports  120   c  and  125   c  may be closed to generate a low pressure. 
     The refrigerant flowing through the first and second heat exchangers  110  and  115  may be heat-exchanged with water to heat the water. The heated water may be introduced into the first and second indoor units  60  and  70  to perform heating. Also, the refrigerant condensed in the first heat exchanger  110  may be decompressed while passing through the first expansion valve  140  of the fourth connection pipe  134 , and the refrigerant condensed in the second heat exchanger  115  may be decompressed while passing through the second expansion valve  145  of the seventh connection pipe  137 . 
     Also, the refrigerant passing through the first and second expansion valves  140  and  145  may be mixed with each other in the third branch part  134   a  and may be introduced into the outdoor unit  10   a  through the second outdoor unit connection pipe  27   a . The refrigerant introduced into the outdoor unit  10   a  may be additionally decompressed in the main expansion valve  18 , evaporated in the outdoor heat exchanger  15 , and then suctioned into the compressor  11 . 
     The second bypass valve  243  may be closed, and the third bypass valve  245  may be opened. Accordingly, the third connection pipe  133  and the eighth connection pipe  138  may be connected to a low pressure-side environment through the third bypass pipe  230 . That is, the third and eighth connection pipes  133  and  138  connected to the third ports  120   c  and  125   c  requiring the low pressure in the first and second four-way valves  120  and  125  may be connected to the second outdoor unit connection pipe  27   a  to easily generate the low pressure. 
     However, the refrigerant of the fourth connection pipe  134  may be prevented from flowing to the third bypass pipe  230  by the third check valve  255 . When it is detected that the switching to the heating operation mode is performed in the first and second four-way valves  120  and  125  by the circulation of the refrigerant, the heating operation mode may be performed as described below. 
       FIG. 8  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during the heating operation mode of the air conditioning apparatus. 
     Referring to  FIG. 8 , the heating operation mode in the air conditioning apparatus  1   a  is substantially similar to the “heating operation switching mode”, except that the third bypass valve  245  is closed. 
     That is, when the heating operation is performed, the refrigerant compressed by the compressor  11  of the outdoor unit  10   a  may be introduced into the third connection pipe  133  through the first outdoor unit connection pipe  25   a . Here, since the first bypass valve  241  is opened, the refrigerant may be introduced into a first bypass pipe  210  from a second bypass branch part  133   b . Also, the refrigerant may be prevented from flowing from a second bypass branch part  133   b  to a fifth bypass branch part  133   c  by a fourth check valve  257 . 
     The refrigerant of the first bypass pipe  210  may be introduced into the first four-way valve  120  through the first connection pipe  131 , and a portion of the refrigerant may be introduced into the fifth connection pipe  135  from the first branch part  131   a  and may be introduced into the second four-way valve  125 . 
     The refrigerant introduced into the first four-way valve  120  may be discharged through the second port  120   b  and introduced into the first heat exchanger  110 , and the refrigerant introduced into the second four-way valve  125  may be discharged through the second port and be introduced into the second heat exchanger  115  through the second port  125   b.    
     The refrigerant flowing through the first and second heat exchangers  110  and  115  may be heat-exchanged with water to heat the water. The heated water may be introduced into the first and second indoor units  60  and  70  to perform heating. Also, the refrigerant condensed in the first heat exchanger  110  may be decompressed while passing through the first expansion valve  140  of the fourth connection pipe  134 , and the refrigerant condensed in the second heat exchanger  115  may be decompressed while passing through the second expansion valve  145  of the seventh connection pipe  137 . 
     Also, the refrigerant passing through the first and second expansion valves  140  and  145  may be mixed with each other in the third branch part  134   a  and may be introduced into the outdoor unit  10   a  through the second outdoor unit connection pipe  27   a . The refrigerant introduced into the outdoor unit  10   a  may be additionally decompressed in the main expansion valve  18 , evaporated in the outdoor heat exchanger  15 , and then suctioned into the compressor  11 . 
     The second bypass valve  243  and the third bypass valve  245  may be closed. Also, the refrigerant of the fourth connection pipe  134  may be prevented from flowing to the third bypass pipe  230  by the third check valve  255 . Due to the circulation of the refrigerant, the heating operation in the first and second indoor units  60  and  70  may be performed. 
       FIG. 9  is a cycle diagram illustrating an example of a flow of the refrigerant in the heat exchange device and the switching mechanism during a cooling operation switching mode of the air conditioning apparatus. 
     While the heating operation mode as shown in  FIG. 8  is performed, a signal for performing the cooling operation may be inputted. In this case, as the cooling operation mode starts, a “cooling operation switching mode” may be performed at the beginning of the cooling operation mode. 
     In detail, when the “cooling operation switching mode” is performed, the refrigerant condensed in the outdoor heat exchanger  15  of the outdoor unit  10   a  may be introduced into the fourth connection pipe  134  through the second outdoor unit connection pipe  27   a.    
     The refrigerant of the fourth connection pipe  134  may be decompressed in the first expansion valve  140  and then be introduced into the first heat exchanger  110 , and a portion of the refrigerant may be branched from the third branch part  134   a  to the seventh connection pipe, decompressed in the second expansion valve  145 , and introduced into the second heat exchanger. Also, the refrigerant may be evaporated by being heat-exchanged with the first and second water flow paths  112  and  118  in the first and second heat exchangers  110  and  115 , respectively. In this process, the water of the first and second water flow paths  112  and  118  may be cooled to perform the cooling operation of the first and second indoor units  60  and  70 . 
     The refrigerant discharged from the first heat exchanger  110  may be introduced into the first four-way valve  120  through the second port  120   b  and may be discharged from the first four-way valve  120  through the third port  120   c . Also, the refrigerant discharged from the second heat exchanger  115  may be introduced into the second four-way valve  125  through the second port  125   b  and may be discharged from the second four-way valve  125  through the third port  125   c.    
     The refrigerant discharged from the first four-way valve  120  flows through the third connection pipe  133 , and the refrigerant discharged from the second four-way valve  125  flows through the eighth connection pipe  138  and then is mixed with the refrigerant of the third connection pipe  133  in the second branch part  133   a . The mixed refrigerant may be introduced into the outdoor unit  10   a  through the first outdoor unit connection pipe  25   a  and suctioned into the compressor  11 . 
     The second bypass valve  243  may be opened, and the third bypass valve  245  may be closed. Therefore, a portion of the refrigerant of the fourth connection pipe  134  may be introduced into the first connection pipe  131  through the second bypass pipe  220 . The refrigerant of the first connection pipe  131  may be introduced into the first four-way valve  120  through the first port  120   a.    
     In some examples, a portion of the refrigerant may be introduced into the fifth connection pipe  135  from the first branch part  131   a  and may be introduced into the second four-way valve  125  through the first port  125   a.    
     Therefore, a high pressure may be generated at a side of the first port  120   a  within the first four-way valve  120 , and thus, the second and third ports  120   b  and  120   c  in which the refrigerant flows may communicate with each other to generate a low pressure. Therefore, a differential pressure may be secured between the first port  120   a  and the second and third ports  120   b  and  120   c . As a result, switching to the cooling operation may be made easily. 
     Also, a high pressure may be generated at a side of the first port  125   a  within the second four-way valve  125 , and thus, the second and third ports  125   b  and  125   c  in which the refrigerant flows may communicate with each other to generate a low pressure. Therefore, a differential pressure may be secured between the first port  125   a  and the second and third ports  125   b  and  125   c . As a result, switching to the cooling operation may be made easily. 
     In the “cooling operation switching mode” process, when the differential pressure is detected to be a set differential pressure, for example, about 350 kpa or more, the second bypass valve  243  may be controlled to be closed, and the “cooling operation mode” described in  FIG. 6  may be performed. 
     In some implementations, the heat exchange device performing the heat exchange between the water and the refrigerant may increases in degree of freedom of the installation by the switching mechanism that is capable of being connected to the switchable outdoor unit and the simultaneous outdoor unit, which have the internal configurations different from each other. 
     The switching mechanism may be configured to be connected to the simultaneous outdoor unit through the three pipes and to be connected to the switchable outdoor unit through the two pipes and may be disposed between the heat exchange device and the outdoor unit so that the heat exchange device performing the heat exchange between the water and the refrigerant increases in degree of freedom of the installation. 
     The switching mechanism may include the bypass pipe through which the four-way valve and the connection pipe of the refrigerant having the specific pressure to generate the high pressure or the low pressure at the specific port of the four-way valve communicate with each other so that an internal differential pressure of the four-way valve is used when changing a cooling operation mode or a heating operation mode. 
     The internal differential pressure may be sufficiently secured to improve the operation reliability of the four-way valve in the cooling operation mode or the heating operation mode. 
     Although implementations have been described with reference to a number of illustrative implementations thereof, it should be understood that numerous other modifications and implementations 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.