JP2008175436A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve efficiency of a defrosting operation by sufficiently securing the amount of a refrigerant used in defrosting, in a refrigerating device capable of performing the defrosting operation for defrosting a plurality of use-side heat exchangers. <P>SOLUTION: In the defrosting operation, a first individual defrosting motion for defrosting a first cooling heat exchanger 102, and a second individual defrosting motion for defrosting a second cooling heat exchanger 112 are alternately performed. During the defrosting operation, a discharging motion is performed for sending the refrigerant in the cooling heat exchangers 102, 112 which are not defrosted by each individual defrosting motion, to the cooling heat exchangers 102, 112 side to be defrosted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus including a plurality of usage-side heat exchangers, and particularly relates to a refrigeration apparatus capable of defrosting operation for performing a refrigeration cycle for defrosting the plurality of usage-side heat exchangers.

  Conventionally, a refrigeration apparatus having a refrigerant circuit that performs a refrigeration cycle is known, and is widely applied to cooling apparatuses such as refrigerators and freezers that store foods, air conditioning apparatuses that perform indoor cooling and heating, and the like. Yes.

  For example, Patent Document 1 discloses an air conditioner capable of a two-stage compression refrigeration cycle. The refrigerant circuit of the air conditioner is provided with a high stage compressor, a low stage compressor, an outdoor heat exchanger, and an indoor heat exchanger. During heating of this refrigeration apparatus, a low-stage compressor and a high-stage compressor are operated, and a two-stage compression refrigeration cycle is performed in which the indoor heat exchanger serves as a condenser and the outdoor heat exchanger serves as an evaporator. In addition, in this air conditioner, defrost operation is possible in which frost adhering to the outdoor heat exchanger is melted in winter. During this defrost operation, only the high-stage compressor is operated, and a refrigeration cycle (so-called reverse cycle defrost) is performed in which the outdoor heat exchanger serves as a condenser and the indoor heat exchanger serves as an evaporator.

Further, Patent Document 2 discloses a refrigeration apparatus that cools the interior with a plurality of usage-side heat exchangers. In this refrigeration apparatus, use side circuits each having a plurality of use side heat exchangers are connected in parallel to a heat source side circuit having a heat source side heat exchanger. During the cooling operation of the refrigeration apparatus, a refrigeration cycle is performed in which the heat source side heat exchanger serves as a condenser and each use side heat exchanger serves as an evaporator. As a result, the air in each warehouse is cooled by each use side heat exchanger.
JP 2004-85047 A JP 2002-228297 A

  By the way, in the refrigeration apparatus provided with a plurality of use side heat exchangers as disclosed in Patent Document 2, it is considered that the defrost operation disclosed in Patent Document 1 is performed to simultaneously defrost each use side heat exchanger. It is done. However, in the defrost operation by such reverse cycle defrost, the condensed refrigerant accumulates as a liquid refrigerant in the use side heat exchanger, and so-called refrigerant stagnation may occur. For this reason, when a plurality of usage-side heat exchangers are defrosted simultaneously as described above, the total amount of refrigerant that accumulates in each usage-side heat exchanger also increases, so a sufficient amount of refrigerant can be secured for defrosting. It may disappear. As a result, there arises a problem that each use side heat exchanger cannot be defrosted efficiently.

  In particular, in a refrigeration apparatus that performs the above-described two-stage compression refrigeration cycle, the pressure on the low-pressure side is extremely low, and the capacity of each use-side heat exchanger often increases. For this reason, when defrosting of a plurality of usage-side heat exchangers is performed with such a refrigeration apparatus, the amount of refrigerant that accumulates in each usage-side heat exchanger increases, and the amount of refrigerant used for defrosting is ensured. It becomes even more difficult.

  The present invention has been made in view of such points, and the object of the present invention is to reduce the amount of refrigerant used for defrost in a refrigeration apparatus capable of defrosting to defrost a plurality of usage-side heat exchangers. The aim is to increase the efficiency of the defrost operation by ensuring sufficient capacity.

  The first invention includes a heat source side circuit (40) having a compressor (41, 42, 43) and a heat source side heat exchanger (44), each having a use side heat exchanger (102, 112) and the heat source side. A plurality of use side circuits (100, 120, 110, 160) connected in parallel to the circuit (40), the heat source side heat exchanger (44) serving as a condenser, and the use side heat exchanger (102, 112) serving as an evaporator. A refrigeration apparatus capable of switching between a cooling operation for performing a refrigeration cycle and a defrost operation for performing a refrigeration cycle in which the use side heat exchanger (102, 112) serves as a condenser and the heat source side heat exchanger (44) serves as an evaporator. It is assumed. In the refrigeration apparatus, during the defrost operation, the individual defrosting operation in which a part of the plurality of use side heat exchangers (102, 112) is a condenser and the rest is in a dormant state is performed for all use side heat exchanges. The use side heat exchanger (102, 112) that becomes a condenser every time so that the condenser (102, 112) once becomes a condenser, and performs the heat several times while changing the use side heat exchanger (102, 112). A discharge operation for discharging the refrigerant from the exchanger (102, 112) is performed.

  In the refrigeration apparatus of the first invention, a refrigerant circuit is configured by connecting a plurality of use side circuits (100, 120, 110, 160) in parallel to the heat source side circuit (40). In this refrigeration apparatus, for example, a cooling operation for cooling the inside of the freezer by each use side heat exchanger (102, 112) and a defrost operation for melting frost on the surface of each use side heat exchanger (102, 112) are possible. .

  Specifically, in the cooling operation, the refrigerant compressed by the compressor (41, 42, 43) is condensed by the heat source side heat exchanger (44), and then depressurized by an expansion valve, etc. It is sent to the exchanger (102, 112). In each use side heat exchanger (102, 112), the refrigerant absorbs heat from the air and evaporates. As a result, for example, the air in the freezer is cooled. The refrigerant evaporated in each use side heat exchanger (102, 112) is sucked into the compressor (41, 42, 43) and compressed again.

  On the other hand, in the defrost operation of the present invention, only the use side heat exchangers (102, 112) to be defrosted become condensers, and the remaining use side heat exchangers (102, 112) become out of defrost targets and enter a dormant state. An individual defrost operation is performed. This individual defrosting operation will be described with specific examples.

  In the individual defrosting operation, for example, it is assumed that the first usage-side heat exchanger (102) is to be defrosted and the second usage-side heat exchanger (112) is not to be defrosted. In this case, the refrigerant compressed by the compressor (41, 42, 43) is sent only to the first usage-side heat exchanger (102) and sent to the second usage-side heat exchanger (112). Absent. In the first usage-side heat exchanger (102), the refrigerant dissipates heat against the frost attached to the surface of the heat transfer tube. As a result, in the first use side heat exchanger (102), the refrigerant condenses, while the frost on the surface of the heat transfer tube gradually melts and is defrosted. The refrigerant condensed in the first use side heat exchanger (102) is depressurized by an expansion valve or the like and then evaporated in the heat source side heat exchanger (44). The refrigerant evaporated in the heat source side heat exchanger (44) is sucked into the compressor (41, 42, 43) and compressed again.

  In the defrost operation of the present invention, the individual defrost operation as described above is repeatedly performed so as to gradually change the defrost target in a predetermined order. That is, after the individual defrosting operation in the above example is completed, the second usage-side heat exchanger (112) becomes a defrost target (condenser), and the first usage-side heat exchanger (102) is defrosted. An individual defrosting operation that is out of the target (pause state) is performed. Therefore, in the present invention, for example, one use side heat is compared with the case where the refrigerant is divided into the use side heat exchangers (102, 112) and the respective use side heat exchangers (102, 112) are defrosted simultaneously. The amount of refrigerant that can be sent to the exchanger (102, 112) increases. Therefore, in the individual defrosting operation, even if the refrigerant stagnates in the use side heat exchanger (102, 112), the amount of refrigerant used for the defrost of each use side heat exchanger (102, 112) will not be insufficient. .

  Further, during the defrost operation of the present invention, a discharge operation is performed to discharge the refrigerant in the use side heat exchangers (102, 112) that are not to be defrosted. That is, during the individual defrosting operation, the refrigerant may remain in the use side heat exchanger (102, 112) on the dormant side. In the present invention, this refrigerant is discharged by the discharge operation. Therefore, in the individual defrosting operation, the amount of refrigerant that can be sent to the use side heat exchangers (102, 112) to be defrosted further increases.

  According to a second aspect of the present invention, in the refrigeration apparatus of the first aspect, the heat source side circuit (40) is provided with a high stage compressor (41, 42, 43), while each of the use side circuits (100, 120, 110, 160). Are provided with low-stage compressors (121, 122, 123, 161, 162, 163), respectively, and in the cooling operation, the high-stage compressor (41, 42, 43) and the low-stage compressor (121, 122, 123, 161, 162, 163) are operated to perform two-stage compression refrigeration. In the defrost operation, the high-stage compressor (41, 42, 43) is operated to perform the refrigeration cycle. In the discharge operation, the use-side heat exchange that is not to be defrosted is performed. Operating the low-stage compressor (121,122,123,161,162,163) of the use side circuit (100,120,110,160) corresponding to the cooler (102,112) to use the refrigerant in the use side heat exchanger (102,112) outside the defrost target It is characterized by being sent to the side heat exchanger (102, 112) side.

  In the refrigeration apparatus of the second invention, a two-stage compression refrigeration cycle is configured. That is, the refrigerant circuit of this refrigeration apparatus is provided with a high stage compressor (41, 42, 43) and a low stage compressor (121, 122, 123, 161, 162, 163). In the cooling operation of this refrigeration system, the refrigerant compressed by the high stage side compressor (41, 42, 43) is condensed by the heat source side heat exchanger (44), depressurized by a pressure reducing valve, etc. It is sent to the exchanger (102, 112). The refrigerant evaporated in each use-side heat exchanger (102, 112) is compressed by each low-stage compressor (121, 122, 123, 161, 162, 163) and then sucked into the high-stage compressor (41, 42, 43) for further compression. The

  On the other hand, in the defrosting operation of the refrigeration apparatus, the individual defrosting operation is performed while the high-stage compressor (41, 42, 43) is in an operating state. Specifically, in the individual defrosting operation, the refrigerant compressed by the high stage compressor (41, 42, 43) is sent to the first use side heat exchanger (102) to be defrosted, for example. It is not sent to the second usage side heat exchanger (112) that is not subject to defrosting. The refrigerant used for defrosting the first use side heat exchanger (102) is decompressed by an expansion valve or the like, condensed by the heat source side heat exchanger (44), and then the high stage compressor (41, 42). , 43) and compressed again.

  Here, in the discharge operation of the present invention, by operating the low-stage compressor (121, 122, 123, 161, 162, 163) of the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) that is not subject to defrosting in the individual defrost operation. Then, the refrigerant is sent to the use side heat exchanger (102, 112) to be defrosted. Specifically, for example, in the individual defrosting operation, when the second usage-side heat exchanger (112) is on the dormant side, the second usage-side circuit corresponding to the second usage-side heat exchanger (112) ( 110,160) second low stage compressor (161,162,163) is operated. As a result, the refrigerant accumulated in the second usage-side heat exchanger (112) is sucked into the second low-stage compressor (161, 162, 163) and compressed, and the first usage-side heat to be defrosted. It is sent to the exchanger (102). At this time, in the second usage-side circuit (110, 160), the refrigerant accumulated in the suction-side piping or the like of the second low-stage compressor (161, 162, 163) is also transferred to the first usage-side heat exchanger (102. ). Therefore, in the individual defrosting operation, the amount of refrigerant that can be sent to the use side heat exchangers (102, 112) to be defrosted further increases.

  According to a third aspect of the present invention, in the refrigeration apparatus according to the second aspect of the present invention, each of the use side circuits (100, 120, 110, 160) includes an expansion valve (101, 111) that depressurizes the refrigerant on the inflow side of the use side heat exchanger (102, 112) during the cooling operation. ) Are provided, and in the individual defrosting operation, the expansion valve (101,111) of the utilization side circuit (100,120,110,160) corresponding to the utilization side heat exchanger (102,112) to be defrosted is opened, and the utilization side not to be defrosted is utilized. The expansion valve (101, 111) of the use side circuit (100, 120, 110, 160) corresponding to the heat exchanger (102, 112) is fully closed.

  In the third invention, the expansion valves (101, 111) are provided in the respective use side circuits (100, 120, 110, 160). In the cooling operation, the refrigerant condensed in the heat source side heat exchanger (44) is depressurized by the expansion valves (101, 111), and then sent to the use side heat exchangers (102, 112) to evaporate.

  On the other hand, in the individual defrosting operation, the expansion valve (101, 111) is opened in the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) to be defrosted. On the other hand, in the utilization side circuit (100, 120, 110, 160) that is not the object of defrosting, the expansion valve (101, 111) is fully closed. When the high-stage compressor (41, 42, 43) is operated in this state, the refrigerant discharged from the high-stage compressor (41, 42, 43) is used on the use-side heat exchanger (102, 112) to be defrosted. ). On the other hand, the expansion valve (101, 111) in the fully closed state is prohibited from flowing through the use side heat exchanger (102, 112) that is not subject to defrosting. Therefore, in the individual defrosting operation, the amount of refrigerant that can be sent to the use side heat exchanger (102, 112) to be defrosted increases.

  In a refrigeration apparatus according to a fourth aspect of the present invention, in the refrigeration apparatus according to the third aspect of the present invention, in the discharge operation, the expansion valve ( 101, 111) are fully closed.

  In the discharge operation of the fourth aspect of the invention, in the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) that is not to be defrosted, the expansion valve (101, 111) is fully closed and the low stage compressor (121,122,123,161,162,163) is operated. Specifically, for example, in the second usage-side circuit (110, 160) on the pause side, the second expansion valve (111) is fully closed, and the second low-stage compressor (161, 162, 163) is operated. As a result, in the second utilization side circuit (110, 160), the refrigerant remaining between the fully closed second expansion valve (111) and the suction port of the second low-stage compressor (161, 162, 163). Are sucked into the second low-stage compressor (161, 162, 163), compressed, and sent to the first use side heat exchanger (102) to be defrosted. Therefore, in the individual defrosting operation, the amount of refrigerant that can be sent to the use side heat exchangers (102, 112) to be defrosted further increases.

  In addition, when the expansion valves (101, 111) are fully closed in this way, the pressure on the suction side of the low-stage compressor (121, 122, 123, 161, 162, 163) that is in the operating state rapidly decreases. For this reason, even if the liquid refrigerant is accumulated in the usage-side heat exchangers (102, 112) and the pipes before and after the defrost target, the liquid refrigerant is rapidly decompressed and easily evaporated. Therefore, it is avoided that the refrigerant is sucked into the low-stage compressor (121, 122, 123, 161, 162, 163) in the liquid state, and so-called liquid compression phenomenon in the low-stage compressor (121, 122, 123, 161, 162, 163) can be prevented.

  According to a fifth invention, in the refrigeration apparatus according to any one of the second to fourth inventions, the use side circuit (100, 120, 110, 160) connects the suction side and the discharge side of the low-stage compressor (121, 122, 123, 161, 162, 163). In addition, bypass pipes (145, 185) having on-off valves (SV6, SV11) that are closed during the cooling operation are respectively provided, and the individual defrost operation corresponds to the use side heat exchanger (102, 112) to be defrosted. The open / close valve (SV6, SV11) of the use side circuit (100, 120, 110, 160) is opened, and the open / close valve (SV6, SV11) of the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) not subject to defrosting is closed It is characterized by that.

  In the fifth aspect of the present invention, the bypass pipes (145, 185) are provided in the respective use side circuits (100, 120, 110, 160). During the cooling operation, the open / close valves (SV6, SV11) of the bypass pipes (145, 185) are closed. For this reason, the refrigerant evaporated in each use side heat exchanger (102, 112) is compressed in each low stage compressor (121, 122, 123, 161, 162, 163) without flowing through the bypass pipe (145, 185), and then the high stage compressor (41, 112). 42, 43).

  On the other hand, in the individual defrosting operation, the release valves (SV6, SV11) of the use side circuits (100, 120, 110, 160) corresponding to the use side heat exchangers (102, 112) that are not defrosted are closed. For this reason, the refrigerant compressed by the high-stage compressor (41, 42, 43) is sent to the use-side heat exchanger (101, 112) that is not to be defrosted through the bypass pipe (145, 185). Prohibited by release valves (SV6, SV11). Therefore, in the individual defrosting operation, the amount of refrigerant that can be sent to the use side heat exchanger (102, 112) to be defrosted increases.

  6th invention is the refrigerating apparatus of 5th invention. WHEREIN: In said discharge | emission operation | movement, the on-off valve (SV6, SV11) of the utilization side circuit (100,120,110,160) corresponding to the utilization side heat exchanger (102,112) which is not a defrost object Is characterized by being closed.

  In the discharge operation according to the sixth aspect of the invention, in the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) not subject to defrosting in the individual defrost operation, the on-off valve (SV6, SV11) is closed and low. The stage side compressors (121, 122, 123, 161, 162, 163) are operated. Specifically, for example, in the second usage-side circuit (110, 160) corresponding to the second usage-side heat exchanger (112) on the suspension side, the on-off valve (SV11) is closed and the second low-stage side compression is performed. The machine (161, 162, 163) is operated. As a result, in the second usage side circuit (110, 160), the refrigerant discharged from the second low stage compressor (161, 162, 163) passes through the second bypass pipe (185), and the second low stage compressor (161, 162, 163). It is prohibited to return to the inhalation side. Accordingly, the refrigerant accumulated in the second use side circuit (110, 160) can be quickly discharged, and the amount of refrigerant that can be sent to the use side heat exchanger (102, 112) to be defrosted in the individual defrosting operation is further increased. become.

  In a refrigeration apparatus according to a fifth aspect, in the refrigeration apparatus according to the fifth aspect, the oil in the refrigerant discharged from each low-stage compressor (121,122,123,161,162,163) is supplied to each use-side circuit (100,120,110,160). ) Are provided with container-like oil separators (124,164), and each of the bypass pipes (145,185) has one end connected to each oil separator (124,164). is there.

  In the seventh invention, an oil separator (124, 164) is provided on the discharge side of each low-stage compressor (121, 122, 123, 161, 162, 163). The oil separator (124, 164) separates oil from the refrigerant discharged from the low-stage compressor (121, 122, 123, 161, 162, 163), for example, during the cooling operation. The oil separated by the oil separator (124, 164) is sucked into the low-stage compressor (121, 122, 123, 161, 162, 163) through an oil return pipe or the like and used for lubricating the compression mechanism or the like.

  By the way, if the oil separators (124, 164) are provided in the respective use side circuits (100, 120, 110, 160) as described above, the refrigerant may also accumulate in the oil separators (124, 164) during the defrost operation. That is, in the defrost operation, the high stage compressor (41, 42, 43) and the refrigerant outflow pipe in each oil separator (124, 164) communicate with each other. , 43) may accumulate in each oil separator (124, 164). As a result, in the defrost operation, the amount of refrigerant that can be sent to each usage-side heat exchanger (102, 112) is insufficient, and the defrosting capacity of each usage-side heat exchanger (102, 112) is reduced. There is.

  Therefore, in the present invention, one end of the bypass pipe (145, 185) is connected to the oil separator (124, 164) in order to avoid such accumulation of refrigerant in each oil separator (124, 164). For this reason, in the defrosting operation of the present invention, the refrigerant discharged from the high-stage compressor (41, 42, 43) flows through the oil separator (124, 164) and then flows out to the bypass pipe (145, 185) to be defrosted. To the use side heat exchanger (102, 112). That is, during the defrost operation, the refrigerant in the oil separator (124, 164) is always pushed out to the bypass pipe (145, 185), so the accumulation of refrigerant in the oil separator (124, 164) is avoided, and the defrost target The amount of refrigerant that can be sent to the use side heat exchangers (102, 112) is further increased.

  An eighth invention is characterized in that, in the refrigeration apparatus of the seventh invention, each of the bypass pipes (145, 185) has one end connected to the bottom of each of the oil separators (124, 164).

  In the eighth invention, one end of the bypass pipe (145, 185) is connected to the bottom of the oil separator (124, 164). For this reason, the refrigerant accumulated in the oil separator (124, 164) during the defrost operation easily flows out to the bypass pipe (145, 185). Further, even if the refrigerant in the oil separator (124, 164) is condensed and liquid refrigerant is accumulated at the bottom, the liquid refrigerant quickly flows out to the bypass pipe (145, 185).

  According to a ninth aspect of the present invention, in the refrigeration apparatus according to any one of the first to eighth aspects, each of the use side heat exchangers (102, 112) is provided in the same box and each has the same fin (102a). ) Is shared.

  In the ninth invention, the use side heat exchangers (102, 112) are arranged in the same cabinet. Moreover, each use side heat exchanger (102,112) shares the same fin (102a). Therefore, in the individual defrosting operation of the present invention, when the use side heat exchanger (102, 112) to be defrosted is used as a condenser, the heat of the refrigerant in the use side heat exchanger (102, 112) is converted into the fin (102a). It is also transmitted to the remaining use side heat exchangers (102, 112) via. As a result, in the individual defrosting operation, the frost on the surface of the dormant use side heat exchanger (102, 112) can be melted using the heat of the use side heat exchanger (102, 112) on the condenser side.

  According to a tenth invention, in the refrigeration apparatus according to any one of the first to ninth inventions, in the defrost operation, the degree of supercooling of the refrigerant flowing out of the use side heat exchanger (102, 112) to be defrosted is predetermined. The defrost target of the individual defrost operation is changed when the temperature is higher than the temperature.

  In the defrosting operation of the tenth invention, the condensed liquid refrigerant is accumulated in the use side heat exchanger (102, 112) to be defrosted, and when the degree of supercooling of the liquid refrigerant exceeds a predetermined temperature, the defrosting of the individual defrost is performed. The target is changed. As a result, even if the individual defrosting operation is repeated while appropriately changing the use side heat exchangers (102, 112) to be defrosted, liquid refrigerant may not accumulate in each use side heat exchanger (102, 112). To be avoided. Therefore, it is more reliably avoided that the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112) is insufficient.

  In an eleventh aspect of the invention, in the refrigeration apparatus according to any one of the first to ninth aspects, in the defrost operation, the temperature of the refrigerant flowing out of the use side heat exchanger (102, 112) to be defrosted is equal to or higher than a predetermined temperature. Then, the defrost target of the individual defrost operation is changed.

  In the defrost operation of the eleventh aspect of the invention, when the condensed liquid refrigerant is accumulated in the use side heat exchanger (102, 112) to be defrosted and the temperature of the refrigerant in the use side heat exchanger (102, 112) becomes equal to or higher than a predetermined temperature. The defrost target of the individual defrost is changed. As a result, even if the individual defrosting operation is repeated while appropriately changing the use side heat exchangers (102, 112) to be defrosted, liquid refrigerant may not accumulate in each use side heat exchanger (102, 112). To be avoided. Therefore, it is more reliably avoided that the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112) is insufficient.

  In the present invention, in the defrost operation, the use-side heat exchanger (102, 112) to be defrosted is appropriately changed from the plurality of use-side heat exchangers (102, 112) to perform the individual defrost operation. For this reason, according to this invention, compared with the case where all the some use side heat exchangers (102,112) are defrosted as a condenser, the quantity of the refrigerant | coolant which accumulates in the use side heat exchanger (102,112). Less. Therefore, in this individual defrost operation, the amount of refrigerant used for defrosting of the use side heat exchangers (102, 112) can be sufficiently secured, so that the efficiency of the defrost operation can be increased.

  Further, according to the present invention, a discharge operation is performed in which the refrigerant in the usage-side heat exchanger (102, 112) that is not to be defrosted by the individual defrosting operation is sent to the usage-side heat exchanger (102, 112) that is to be defrosted. ing. Therefore, according to the present invention, the refrigerant that accumulates in the idle-side use-side heat exchanger (102, 112) can be used for defrosting the use-side heat exchanger (102, 112) that is to be defrosted. In addition, the amount of refrigerant used for defrosting of each usage-side heat exchanger (102, 112) can be more reliably ensured.

  In the second invention, in the refrigeration apparatus that performs a two-stage compression refrigeration cycle in which the capacity of the use side heat exchanger (102, 112) is likely to increase, the individual defrosting operation is performed while changing the defrost target. Therefore, according to the present invention, even if a large amount of liquid refrigerant accumulates in the use side heat exchanger (102, 112), the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112) Can be secured sufficiently.

  In the discharge operation of the present invention, the refrigerant compressed by the low-stage compressor (121, 122, 123, 161, 162, 163) is sent to the use-side heat exchanger (102, 112) to be defrosted. If it does in this way, the input heat of a low stage side compressor (121,122,123,161,162,163) can be utilized for the defrost of the utilization side heat exchanger (102,112) used as a defrost object.

  In the third invention, in the individual defrost operation, the expansion valves (101, 111) corresponding to the use side heat exchangers (102, 112) that are not to be defrosted are fully closed. Therefore, according to the present invention, it is possible to reliably prohibit the circulation of the refrigerant in the use side heat exchanger (102, 112) that is not to be defrosted, and send the refrigerant to the use side heat exchanger (102, 112) to be defrosted accordingly. A large amount of refrigerant can be secured.

  In particular, in the discharge operation of the fourth invention, the expansion valves (101, 111) corresponding to the utilization side heat exchangers (102, 112) that are not to be defrosted are fully closed. Therefore, according to the present invention, refrigerant accumulated between the expansion valve (101, 111) and the suction port of the low-stage compressor (121, 122, 123, 161, 162, 163) can be sent to the use-side heat exchanger (102, 112) to be defrosted. it can. Therefore, the amount of refrigerant used for defrosting of the use side heat exchangers (102, 112) to be defrosted can be reliably ensured. Further, by fully closing the expansion valve (101, 111), the refrigerant on the suction side of the low-stage compressor (121, 122, 123, 161, 162, 163) can be gasified, so the liquid compression phenomenon in the low-stage compressor (121, 122, 123, 161, 162, 163) Can be avoided.

  In the fifth aspect of the invention, in each use side circuit (100, 120, 110, 160), a bypass pipe (145, 185) that connects the suction side and the discharge side of the low stage compressor (121, 122, 123, 161, 162, 163) is provided. For this reason, in the individual defrost operation, the refrigerant discharged from the high-stage compressor (41, 42, 43) can be sent to the use side heat exchanger (102, 112) to be defrosted via the bypass pipe (145, 185). it can.

  In particular, in the discharge operation of the sixth invention, the on-off valves (SV6, SV11) corresponding to the use side heat exchangers (102, 112) that are not to be defrosted are closed. For this reason, according to this invention, the refrigerant | coolant compressed with the low stage side compressor (121,122,123,161,162,163) at the time of discharge | emission operation | movement can be rapidly sent to the utilization side heat exchanger (102,112) side of a defrost object. Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of the use side heat exchangers (102, 112) to be defrosted.

  In the seventh invention, one end of the bypass pipe (145, 185) is connected to the oil separator (124, 164). Therefore, in the defrost operation of the present invention, the refrigerant accumulated in the oil separator (124, 164) can be reliably sent to the use side heat exchanger (102, 112) to be defrosted via the bypass pipe (145, 185). Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112).

  In particular, in the eighth invention, since one end of the bypass pipe (145, 185) is connected to the bottom of the oil separator (124, 164), liquid refrigerant or the like accumulated in the oil separator (124, 164) is quickly removed. And can be sent to the use side heat exchanger (102, 112) to be defrosted.

  In the ninth invention, the plurality of usage-side heat exchangers (102, 112) are configured to share the fin (102a). For this reason, at the time of individual defrost operation, in each use side heat exchanger (102, 112), the heat of the refrigerant in the use side heat exchanger (102, 112) on the condenser side is used, and the use side heat exchanger ( 102, 112) can be defrosted. Therefore, it is possible to shorten the time required for defrosting each use side heat exchanger (102, 112).

  Furthermore, in the defrosting operation of the tenth aspect of the invention, the defrost target is changed when the degree of supercooling of the refrigerant flowing out from the use side heat exchanger (102, 112) to be defrosted exceeds a predetermined temperature. For this reason, the stagnation of the refrigerant in each use side heat exchanger (102, 112) can be avoided in advance. Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112).

  In the defrosting operation of the eleventh aspect of the invention, the defrost target is changed when the temperature of the refrigerant flowing out of the use side heat exchanger (102, 112) that is the defrost target becomes equal to or higher than a predetermined temperature. For this reason, the stagnation of the refrigerant in each use side heat exchanger (102, 112) can be avoided in advance. Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of each use side heat exchanger (102, 112).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The refrigeration apparatus (10) of this embodiment is installed in a convenience store or the like and cools the inside of the freezer.

  As shown in FIG. 1, the refrigeration apparatus (10) of the embodiment includes an outdoor unit (11), an expansion unit (12), a supercooling unit (13), a refrigeration showcase (14), and a first booster unit (15). And a second booster unit (16). The outdoor unit (11), the extension unit (12), and the supercooling unit (13) are installed outdoors. On the other hand, the remaining units (14, 15, 16) are all installed in a store such as a convenience store.

  The outdoor unit (11) is provided with an outdoor circuit (40), the expansion unit (12) is provided with an expansion circuit (80), and the supercooling unit (13) is provided with a supercooling circuit (90). The outdoor circuit (40), the expansion circuit (80), and the supercooling circuit (90) are connected in series to constitute a heat source side circuit. The refrigeration showcase (14) includes a first refrigeration circuit (100) and a second refrigeration circuit (110), the first booster unit (15) includes a first booster circuit (120), and a second booster unit (16). Are each provided with a second booster circuit (160). The 1st freezing circuit (100) and the 1st booster circuit (120) are connected in series, and constitute the 1st use side circuit. The 2nd freezing circuit (110) and the 2nd booster circuit (160) are connected in series, and constitute the 2nd use side circuit.

  In this refrigeration apparatus (10), the refrigerant is circulated by connecting the first usage side circuit (100, 120) and the second usage side circuit (110, 160) in parallel to the heat source side circuit (40, 80, 90). Thus, a refrigerant circuit in which a vapor compression refrigeration cycle is performed is configured.

  Specifically, a first closing valve (21) and a second closing valve (22) are provided at the end of the outdoor circuit (40). The second shut-off valve (22) is connected to one end of the expansion circuit (80) via the first connection pipe (31). The other end of the expansion circuit (80) is connected to one end of the supercooling circuit (90) via the second connecting pipe (32). The other end of the supercooling circuit (90) is connected to one end of the first refrigeration circuit (100) and the second refrigeration circuit (110) via the third communication pipe (33). The other end of the first refrigeration circuit (100) is connected to one end of the first booster circuit (120) via the fourth connection pipe (34), and the other end of the second refrigeration circuit (110) is connected to the fifth connection. It is connected to one end of the second booster circuit (160) through the pipe (35). A third closing valve (23) is provided at the other end of the first booster circuit (120), and a fourth closing valve (24) is provided at the other end of the second booster circuit (160). The third closing valve (23) and the fourth closing valve (24) are connected to the first closing valve (21) via the sixth connection pipe (36).

《Outdoor unit》
The outdoor circuit (40) of the outdoor unit (11) includes a first high-stage compressor (41), a second high-stage compressor (42), a third high-stage compressor (43), and outdoor heat exchange. A vessel (44), a receiver (45), an internal heat exchanger (46), an outdoor expansion valve (47), and a four-way switching valve (48) are provided.

  Each of the high-stage compressors (41, 42, 43) is a hermetic type high-pressure dome type scroll compressor. The first higher stage compressor (41) constitutes a variable capacity compressor to which electric power is supplied via an inverter. That is, the capacity of the first high-stage compressor (41) can be changed by changing the rotation speed of the compressor motor by changing the output frequency of the inverter. The second high-stage compressor (42) and the third high-stage compressor (43) constitute a fixed capacity compressor. That is, the second high-stage compressor (42) and the third high-stage compressor (43) are such that the compressor motor is always operated at a constant rotational speed, and the capacities thereof cannot be changed. ing.

  One end of the first discharge pipe (51) is on the discharge side of the first high-stage compressor (41), and one end of the second discharge pipe (52) is on the discharge side of the second high-stage compressor (42). However, one end of the third discharge pipe (53) is connected to the discharge side of the third higher stage compressor (43). The other ends of these discharge pipes (51, 52, 53) are connected to the four-way switching valve (48) via the high-stage discharge pipe (54). A first suction pipe (55) is provided on the suction side of the first high stage compressor (41), and a second suction pipe (56) is provided on the suction side of the second high stage compressor (42). A third suction pipe (57) is connected to the suction side of the third higher stage compressor (43). The other ends of these suction pipes (55, 56, 57) are connected to the four-way switching valve (48) via a high-stage suction pipe (58).

  The high stage side discharge pipe (54) is provided with a high stage side oil separator (59). One end of a high-stage oil return pipe (59a) is connected to the bottom of the high-stage oil separator (59). The other end of the high stage side oil return pipe (59a) is connected to the high stage side suction pipe (58). The high-stage oil return pipe (59a) is provided with a first solenoid valve (SV1) that can be opened and closed. In the high stage side oil separator (59), oil (refrigeration machine oil) is separated from the refrigerant discharged from each high stage side compressor (41, 42, 43). The oil separated by the high-stage oil separator (59) passes through each high-stage compressor (59a) via the high-stage oil return pipe (59a) with the first solenoid valve (SV1) open. 41, 42, 43).

  The outdoor heat exchanger (44) is a cross fin type fin-and-tube heat exchanger, and constitutes a heat source side heat exchanger. An outdoor fan (60) is provided in the vicinity of the outdoor heat exchanger (44). In the outdoor heat exchanger (44), heat is exchanged between the outdoor air blown by the outdoor fan (60) and the refrigerant. One end of the outdoor heat exchanger (44) is connected to the four-way switching valve (48), and the other end is connected to the top of the receiver (45) via the first liquid pipe (61).

  The receiver (45) stores excess refrigerant in the container. The receiver (45) has an internal volume of about 10 L (liter). The first liquid pipe (61) is connected to the top of the receiver (45), and the second liquid pipe (62) is connected to the bottom of the receiver (45).

  The internal heat exchanger (46) includes a first heat transfer tube (46a) and a second heat transfer tube (46b), and exchanges heat between the refrigerants flowing through the heat transfer tubes (46a, 46b). The internal heat exchanger (46) is constituted by, for example, a plate heat exchanger.

  One end of the first heat transfer pipe (46a) is connected to the second liquid pipe (62), and the other end is connected to the second closing valve (22) via the third liquid pipe (63). . One end of the first branch pipe (64) and the second branch pipe (65) is connected to the middle of the third liquid pipe (63). The other ends of the first branch pipe (64) and the second branch pipe (65) are respectively connected in the middle of the first liquid pipe (61). The first branch pipe (64) is provided with the outdoor expansion valve (47). The outdoor expansion valve (47) is an electronic expansion valve whose opening degree can be adjusted, and constitutes a heat source side expansion valve. One end of the first injection pipe (66) is connected to the middle of the first branch pipe (64). The other end of the first injection pipe (66) is connected to the higher stage suction pipe (58). The first injection pipe (66) is provided with a first electric valve (66a) that is an electric valve.

  One end of the second heat transfer pipe (46b) is connected to the middle of the first branch pipe (64) via the second injection pipe (67), and the other end is connected to the high-stage suction pipe (58). ing. The second injection pipe (67) is provided with a second motor operated valve (67a) which is a motor operated valve.

  The four-way selector valve (48) includes first to fourth ports. In the four-way selector valve (48), the first port is connected to the high-stage discharge pipe (54), the second port is connected to the outdoor heat exchanger (44), and the third port is connected to the high-stage intake pipe (58). ), The fourth port is connected to the first closing valve (21), respectively. The four-way switching valve (48) is in a first state (state indicated by a solid line in FIG. 1) in which the first port and the second port communicate with each other and the third port and the fourth port communicate with each other. The first port and the fourth port can communicate with each other, and the second port and the third port can communicate with each other. The second state can be switched to the second state (shown by a broken line in FIG. 1).

  Various sensors are provided in the outdoor circuit (40). Specifically, the first discharge pipe (51) includes a first discharge temperature sensor (71), the second discharge pipe (52) includes a second discharge temperature sensor (72), and a third discharge pipe (53). ) Is provided with a third discharge temperature sensor (73). Each discharge temperature sensor (71, 72, 73) detects the temperature of the refrigerant discharged from each high stage compressor (41, 42, 43). The high stage side discharge pipe (54) is provided with a high stage side high pressure sensor (74), and the high stage suction pipe (58) is provided with a high stage side low pressure sensor (75). The high stage high pressure sensor (74) is the refrigerant pressure on the high pressure side of the outdoor circuit (40), and the high stage low pressure sensor (75) is the pressure of the refrigerant on the low pressure side of the outdoor circuit (40). To detect. An outdoor temperature sensor (76) is provided in the vicinity of the outdoor fan (60). The outdoor temperature sensor (76) detects the temperature of outdoor air around the outdoor heat exchanger (44).

  The outdoor circuit (40) is provided with a plurality of check valves. Specifically, the first check pipe (51) has a first check valve (CV1), the second discharge pipe (52) has a second check valve (CV2), and the third discharge pipe (53). Each is provided with a third check valve (CV3). The first liquid pipe (61) has a fourth check valve (CV4), the third liquid pipe (63) has a fifth check valve (CV5), and the second branch pipe (65) has a second check valve. Six check valves (CV6) are provided. Note that these check valves and the check valves described later allow the refrigerant to flow only in the direction indicated by the arrow in FIG. 1 and prohibit the refrigerant flow in the opposite direction.

  The outdoor circuit (40) is provided with a plurality of closing valves in addition to the first closing valve (21) and the second closing valve (22) described above. Specifically, the first liquid pipe (61) has a fifth closing valve (25), the second liquid pipe (62) has a sixth closing valve (26), and the first branch pipe (64) has a A seventh closing valve (27) is provided.

<Expansion unit>
The expansion circuit (80) of the expansion unit (12) is provided with a refrigerant reservoir (81). This refrigerant | coolant storage device (81) comprises the cylindrical sealed vertical container, and is comprised so that a refrigerant | coolant can be stored in the inside. Specifically, the refrigerant reservoir (81) has an internal volume of about 10L to 15L. One end of a fourth liquid pipe (82) and a fifth liquid pipe (83) are connected to the refrigerant reservoir (81) on the peripheral surface near the bottom. The other end of the fourth liquid pipe (82) is connected to the first connecting pipe (31), and the other end of the fifth liquid pipe (83) is connected to the second connecting pipe (32). The expansion circuit (80) is provided with an eighth closing valve (28) in the fifth liquid pipe (84). And the refrigerant | coolant storage device (81) is comprised so that a refrigerant | coolant can be filled through this 8th closing valve (28).

《Supercooling unit》
The supercooling circuit (90) of the supercooling unit (13) includes a supercooling heat exchanger (91), a supercooling side compressor (92), a supercooling side outdoor heat exchanger (93), and a supercooling side expansion. A valve (94) is provided. The supercooling heat exchanger (91) has a high-pressure side heat transfer tube (91a) and a low-pressure side heat transfer tube (91b), and exchanges heat between the refrigerants flowing through the heat transfer tubes (91a, 91b). The supercooling heat exchanger (91) is constituted by, for example, a plate heat exchanger.

  One end of the high-pressure side heat transfer tube (91a) is connected to the second connection pipe (32), and the other end is connected to the third connection pipe (33). The low pressure side heat transfer tube (91b) is provided in a closed circuit (90a) in which a refrigerant circulates and a vapor compression refrigeration cycle is performed. In this closed circuit (90a), the supercooling side compressor (92), the supercooling side outdoor heat exchanger (93), and the supercooling side expansion valve (94) are sequentially arranged from the outflow side of the low pressure side heat transfer tube (91b). ) Is connected.

  The supercooling side compressor (92) constitutes a variable capacity compressor. The supercooling side outdoor heat exchanger (93) constitutes a cross fin type fin-and-tube heat exchanger. A supercooling side outdoor fan (95) is provided in the vicinity of the supercooling side outdoor heat exchanger (93). In the supercooling side outdoor heat exchanger (93), heat is exchanged between the outdoor air blown by the supercooling side outdoor fan (95) and the refrigerant. The supercooling side expansion valve (94) is an electronic expansion valve whose opening degree is adjustable.

  Further, the closed circuit (90a) of the supercooling unit (13) is provided with a supercooling side low pressure sensor (96) in the suction pipe of the supercooling side compressor (92). The supercooling side low pressure sensor (96) detects the pressure of the refrigerant on the low pressure side of the closed circuit (90a). A supercooling side outdoor temperature sensor (97) is provided in the vicinity of the supercooling side outdoor fan (95). The supercooling side outdoor temperature sensor (97) detects the temperature of the outdoor air around the supercooling side outdoor heat exchanger (93).

《Frozen Showcase》
In the refrigeration showcase (14), the first refrigeration circuit (100) and the second refrigeration circuit (110) branch from the third connection pipe (33) and are provided in parallel. The first refrigeration circuit (100) is provided with a first indoor expansion valve (101) and a first cooling heat exchanger (102), and the second refrigeration circuit (110) is provided with a second indoor expansion valve (111) and a first refrigeration circuit (100). A two-cooling heat exchanger (112) is provided. Each indoor expansion valve (101, 111) is an electronic expansion valve whose opening degree can be adjusted, and constitutes a use side expansion valve.

  Each of the cooling heat exchangers (102, 112) is a cross fin type fin-and-tube heat exchanger, and constitutes a use side heat exchanger. The first cooling heat exchanger (102) and the second cooling heat exchanger (112) are arranged in the same box. Moreover, as shown in FIG. 2, each cooling heat exchanger (102, 112) is arrange | positioned adjacently so that each heat exchanger tube may penetrate the same fin (102a). That is, each cooling heat exchanger (102, 112) shares the same fin (102a) with each other. Further, the heat transfer tubes of the respective cooling heat exchangers (102, 112) may be in contact with each other or may be arranged at a predetermined interval. In FIG. 1, for convenience, the cooling heat exchangers (102, 112) are shown separated from each other. An internal fan (103) is provided in the vicinity of each cooling heat exchanger (102, 112). In each cooling heat exchanger (102, 112), heat exchange is performed between the internal air blown by the internal fan (103) and each refrigerant.

  In the refrigeration showcase (14), a drain pan (104) is installed below the cooling heat exchangers (102, 112). The drain pan (104) constitutes an open container that collects frost and condensed water falling from the surface of each cooling heat exchanger (102, 112). Inside the drain pan (104), a heating pipe part (33a) that forms a part of the third communication pipe (33) is provided. The heating pipe part (33a) is formed along the bottom plate of the drain pan (104). This heating pipe part (33a) melts the frost and ice blocks collected in the drain pan (104) using the heat of the refrigerant flowing inside. In FIG. 1, for convenience, the internal fan (103), the drain pan (104), and the heating pipe (33a) are shown close to the first cooling heat exchanger (102).

  The first refrigeration circuit (100) is provided with a first refrigerant temperature sensor (105) and a second refrigerant temperature sensor (106). The first refrigerant temperature sensor (105) is provided on the inflow side of the first cooling heat exchanger (102) during the cooling operation, and the second refrigerant temperature sensor (106) is the first cooling heat exchanger during the cooling operation. (102) on the outflow side. The second refrigeration circuit (110) is provided with a third refrigerant temperature sensor (115) and a fourth refrigerant temperature sensor (116). The third refrigerant temperature sensor (115) is provided on the inflow side of the second cooling heat exchanger (112) during the cooling operation, and the fourth refrigerant temperature sensor (116) is the second cooling heat exchanger during the cooling operation. (112) is provided on the outflow side. Each temperature sensor (105,106,115,116) detects the temperature of the refrigerant | coolant which flows through a corresponding location, respectively. Further, an internal temperature sensor (107) is provided in the vicinity of the internal fan (103). The internal temperature sensor (107) detects the temperature of the internal air in the freezer showcase (14).

《First booster unit》
The first booster circuit (120) of the first booster unit (15) includes a first low-stage compressor (121), a second low-stage compressor (122), and a third low-stage compressor ( 123). Each of the low-stage compressors (121, 122, 123) is a hermetic type high-pressure dome type scroll compressor. The first low stage compressor (121) constitutes a variable capacity compressor to which electric power is supplied via an inverter. That is, the capacity of the first low-stage compressor (121) can be changed by changing the rotation speed of the compressor motor by changing the output frequency of the inverter. The second low-stage compressor (122) and the third low-stage compressor (123) constitute a fixed capacity compressor. That is, the compressors of the second and third low stage compressors (122, 123) are always operated at a constant rotational speed, and their capacities cannot be changed.

  One end of the fourth discharge pipe (131) is on the discharge side of the first low-stage compressor (121), and one end of the fifth discharge pipe (132) is on the discharge side of the second low-stage compressor (122). However, one end of the sixth discharge pipe (133) is connected to the discharge side of the third low-stage compressor (123). The other ends of these discharge pipes (131, 132, 133) are connected to the third closing valve (23) via the first low-stage discharge pipe (134). A fourth suction pipe (135) is provided on the suction side of the first low stage compressor (121), and a fifth suction pipe (136) is provided on the suction side of the second low stage compressor (122). A sixth suction pipe (137) is connected to the suction side of the third low-stage compressor (123). The other ends of these suction pipes (135, 136, 137) are connected to the fourth connection pipe (34) via a first low-stage suction pipe (138).

  The first low-stage discharge pipe (134) is provided with a first low-stage oil separator (124). The first low-stage oil separator (124) is formed in a cylindrical sealed shape, and one end of the first low-stage oil return pipe (124a) is connected to the bottom of the first low-stage oil separator (124). The other end of the first low stage side oil return pipe (124a) is connected to the first low stage side suction pipe (138). The first low-stage oil return pipe (124a) is provided with a second solenoid valve (SV2). In the first low-stage oil separator (124), the oil (refrigerator oil) in the refrigerant discharged from each of the first to third low-stage compressors (121, 122, 123) is separated. The oil separated by the first low-stage oil separator (124) is compressed through the low-stage oil return pipe (124a) with the second solenoid valve (SV2) open. Inhaled into the machine (121, 122, 123).

  First to third oil discharge pipes (141, 142, 143) are connected to the low-stage compressors (121, 122, 123) of the first booster circuit (120), respectively. Each oil discharge pipe (141, 142, 143) has one end opened to the oil reservoir in the casing of each low stage compressor (121, 122, 123), and the other end connected to the first low stage discharge pipe (134). is doing. The first to third oil discharge pipes (141, 142, 143) are provided with a third solenoid valve (SV3), a fourth solenoid valve (SV4), and a fifth solenoid valve (SV5), respectively. In each oil discharge pipe (141, 142, 143), when each solenoid valve (SV3, SV4, SV5) is opened, excess oil accumulated in each low-stage compressor (121, 122, 123) is transferred to the outdoor circuit (40). It is sent to each high stage compressor (41, 42, 43) side.

  The outdoor circuit (40) is provided with a first escape pipe (144), a first bypass pipe (145), a first suction side injection pipe (146), and a first discharge side injection pipe (147).

  The first relief pipe (144) allows the refrigerant on the suction side of each low-stage compressor (121, 122, 123) to flow in the outdoor circuit (121, 122, 123) when each low-stage compressor (121, 122, 123) is stopped due to failure or the like during the cooling operation described later. 40) to each high stage compressor (41, 42, 43) side. The first relief pipe (144) has one end connected to the suction side of each low-stage compressor (121, 122, 123), and the other end connected to the first low-stage oil separator (124) and the third closing valve (23). Connected between.

  The first bypass pipe (145) allows the refrigerant to bypass the low-stage compressors (121, 122, 123). The first bypass pipe (145) connects the suction side and the discharge side of each low-stage compressor (121, 122, 123). Specifically, one end of the first bypass pipe (145) is connected to the first low-stage suction pipe (138). On the other hand, as shown in FIG. 3, the other end of the first bypass pipe (145) is connected to the bottom of the first low-stage oil separator (124) so that the first low-stage oil return pipe (124a) is connected. )It is connected to the. The first bypass pipe (145) is provided with a sixth solenoid valve (SV6).

  The first suction side injection pipe (146) sends the liquid refrigerant to the suction side of each low stage compressor (121, 122, 123). During the cooling operation, liquid refrigerant is appropriately sucked into the low-stage compressors (121, 122, 123), so that the temperature of the refrigerant discharged from the low-stage compressors (121, 122, 123) is adjusted. The first suction side injection pipe (146) has one end connected to the third communication pipe (33) and the other end connected to the first low stage side suction pipe (138). The first suction side injection pipe (146) is provided with a third electric valve (146a) whose opening degree can be adjusted.

  The 1st discharge side injection pipe (147) sends a liquid refrigerant to the discharge side of each low stage side compressor (121,122,123). During the cooling operation, the liquid refrigerant is mixed with the refrigerant discharged from each low-stage compressor (121, 122, 123), so that the oil remaining in the refrigerant discharged is easily transported together with the refrigerant. In other words, if the refrigerant discharged from each low-stage compressor (121, 122, 123) becomes too dry, the oil in the refrigerant tends to stagnate in the connection pipes, etc., but this oil can be removed by mixing the liquid refrigerant into the refrigerant discharged. It becomes easy to send to each high stage side compressor (41, 42, 43) side of a circuit (40). The first discharge side injection pipe (147) has one end connected to the third connection pipe (33) and the other end connected to the first low-stage side discharge pipe (134). The first discharge side injection pipe (147) is provided with a fourth electric valve (147a) whose opening degree can be adjusted.

  Various sensors are provided in the first booster circuit (120). Specifically, the fourth discharge pipe (131) has a fourth discharge temperature sensor (151), the fifth discharge pipe (132) has a fifth discharge temperature sensor (152), and a sixth discharge pipe (133). ) Is provided with a sixth discharge temperature sensor (153). Each discharge temperature sensor (151, 152, 153) detects the temperature of the refrigerant discharged from each low-stage compressor (121, 122, 123). The first low-stage discharge pipe (134) has a first low-stage-side high-pressure sensor (154), and the first low-stage suction pipe (138) has a first low-stage-side low-pressure sensor (155). Are provided. The first low-stage high-pressure sensor (154) is the refrigerant pressure on the discharge side of the first booster circuit (120), and the first low-stage low-pressure sensor (155) is the first booster circuit (120). The pressure of the refrigerant on the suction side is detected.

  The first booster circuit (120) is provided with a plurality of check valves. Specifically, the fourth discharge pipe (131) has a seventh check valve (CV7), the fifth discharge pipe (132) has an eighth check valve (CV8), and the sixth discharge pipe (133). Each is provided with a ninth check valve (CV9). The first relief pipe (144) is provided with a tenth check valve (CV10).

《Second booster unit》
Since the second booster circuit (160) of the second booster unit (16) has the same configuration as the first booster circuit (120) described above, detailed description thereof is omitted. That is, the second booster circuit (160) is provided with a fourth low-stage compressor (161), a fifth low-stage compressor (162), and a sixth low-stage compressor (163). . The second booster circuit (160) includes seventh to ninth discharge pipes (171, 172, 173), a second low-stage discharge pipe (174), and seventh to ninth suction pipes (175, 176, 177). And a second low-stage suction pipe (178).

  The second booster circuit (160) is provided with a second low-stage oil separator (164), a second low-stage oil return pipe (164a), and fourth to sixth oil discharge pipes (181, 182 and 183). ing. The second low-stage oil return pipe (164a) is provided with a seventh solenoid valve (SV7), and each oil discharge pipe (181, 182, 183) is provided with eighth to tenth solenoid valves (SV8, SV9, SV10). It has been. The second booster circuit (160) is provided with a second escape pipe (184), a second bypass pipe (185), a second suction side injection pipe (186), and a second discharge side injection pipe (187). It has been. The eleventh solenoid valve (SV11) is provided in the second bypass pipe (185), the fifth motor operated valve (186a) is provided in the second suction side injection pipe (186), and the second solenoid pipe (187) is provided in the second discharge side injection pipe (187). Six motor-operated valves (187a) are provided.

  Furthermore, the second booster circuit (160) includes seventh to ninth discharge temperature sensors (191, 192, 193), a second low-stage high-pressure sensor (194), and a second low-stage low-pressure sensor (195). ) And eleventh to fourteenth check valves (CV11, CV12, CV13, CV14).

"Controller unit"
The refrigeration apparatus (10) of the present embodiment is provided with a controller (200) as a control unit. This controller (200) is obtained by each sensor of the outdoor unit (11), the supercooling unit (13), the refrigeration showcase (14), the first booster unit (15), and the second booster unit (16). The detection signal can be input, and a control signal can be output to each component device of these units (11, 13, 14, 15, 16).

-Driving action-
Below, the operation | movement operation | movement of the freezing apparatus (10) of embodiment is demonstrated. In this refrigeration apparatus (10), a cooling operation for cooling the inside of the refrigeration showcase (14) and a defrosting operation for defrosting each cooling heat exchanger (102, 112) in the refrigeration showcase (14) are possible. ing.

<Cooling operation>
In the cooling operation shown in FIG. 4, the four-way selector valve (48) is set to the first state. Further, the outdoor expansion valve (47) is fully closed, and the opening degrees of the supercooling side expansion valve (94), the first indoor expansion valve (101), and the second indoor expansion valve (111) are adjusted as appropriate. In addition, the sixth solenoid valve (SV6) and the eleventh solenoid valve (SV11) are closed, and the remaining solenoid valves are also closed in principle.

  In the cooling operation, the outdoor fan (60), the supercooling side outdoor fan (95), and the internal fan (103) are driven. Also, each high stage compressor (41, 42, 43) in the outdoor circuit (40), each low stage compressor (121, 122, 123) in the first booster circuit (120), each low stage in the second booster circuit (160). The stage side compressors (161, 162, 163) are respectively driven. As a result, in the refrigerant circuit during the cooling operation, a two-stage compression refrigeration cycle is performed in which the outdoor heat exchanger (44) serves as a condenser and each cooling heat exchanger (102, 112) serves as an evaporator.

  Specifically, the refrigerant discharged from each high-stage compressor (41, 42, 43) passes through the high-stage discharge pipe (54) and the four-way switching valve (48), and the outdoor heat exchanger ( 44). In the outdoor heat exchanger (44), the refrigerant dissipates heat to the outdoor air and condenses. The refrigerant condensed in the outdoor heat exchanger (44) passes through the receiver (45) and the first heat transfer pipe (46a) of the internal heat exchanger (46) and flows into the third liquid pipe (63). A part of the refrigerant flowing through the third liquid pipe (63) is depressurized by the second motor operated valve (67a) when flowing through the second injection pipe (67), and then the second transfer of the internal heat exchanger (46). It flows through the heat pipe (46b). In the internal heat exchanger (46), the high-pressure refrigerant flowing through the first heat transfer tube (46a) and the low-pressure refrigerant flowing through the second heat transfer tube (46b) exchange heat. As a result, the heat of the refrigerant in the first heat transfer tube (46a) is taken away as the evaporation heat of the refrigerant in the second heat transfer tube (46b). That is, in the internal heat exchanger (46), the refrigerant flowing through the first heat transfer tube (46a) is cooled. The refrigerant evaporated in the second heat transfer pipe (46b) flows into the higher stage suction pipe (58).

  The refrigerant flowing out of the third liquid pipe (63) passes through the refrigerant reservoir (81) and then flows through the high-pressure side heat transfer pipe (91a) of the supercooling heat exchanger (91). On the other hand, in the closed circuit (90a) of the supercooling unit (13), a vapor compression refrigeration cycle is performed. That is, in the closed circuit (90a), the refrigerant compressed by the supercooling side compressor (92) is condensed by the supercooling side outdoor heat exchanger (93) and depressurized by the supercooling side expansion valve (94). To the low pressure side heat transfer tube (91b) of the supercooling heat exchanger (91). In the supercooling heat exchanger (91), the heat of the refrigerant in the high pressure side heat transfer tube (91a) is taken as the evaporation heat of the refrigerant in the low pressure side heat transfer tube (91b). That is, in the supercooling heat exchanger (91), the refrigerant flowing through the high pressure side heat transfer tube (91a) is further cooled.

  The refrigerant that has flowed out of the high-pressure side heat transfer tube (91a) of the supercooling heat exchanger (91) flows through the third connection pipe (33) and flows through the heating pipe section (33a). Here, in the drain pan (104), frost that has fallen from the surface of each cooling heat exchanger (102, 112) and ice blocks in which condensed water has been frozen accumulate. For this reason, when the drain pan (104) is heated by the refrigerant flowing through the heating pipe section (33a), frost and ice blocks in the drain pan (104) are melted. The water melted in the drain pan (104) is discharged from the drain pan (104) through a drain pipe or the like. On the other hand, the refrigerant flowing through the heating pipe part (33a) is further cooled by the heat of fusion being taken away by frost and ice blocks in the drain pan (104). The refrigerant flowing out of the heating pipe part (33a) is divided into the first refrigeration circuit (100) and the second refrigeration circuit (110).

  The refrigerant flowing into the first refrigeration circuit (100) is reduced in pressure when passing through the first indoor expansion valve (101), and then flows through the first cooling heat exchanger (102). In the first cooling heat exchanger (102), the refrigerant absorbs heat from the internal air and evaporates. As a result, the air in the freezer showcase (14) is cooled. The refrigerant evaporated in the first cooling heat exchanger (102) flows into the first booster circuit (120).

  Similarly, the refrigerant flowing into the second refrigeration circuit (110) is depressurized when passing through the second indoor expansion valve (111) and then flows through the second cooling heat exchanger (112). In the second cooling heat exchanger (112), the refrigerant absorbs heat from the internal air and evaporates. The refrigerant evaporated in the second cooling heat exchanger (112) flows into the second booster circuit (160). As described above, the air in the refrigerated showcase (14) is maintained at, for example, -30 ° C.

  The refrigerant flowing into the first booster circuit (120) is sucked into the low-stage compressors (121, 122, 123). The refrigerant compressed by each low-stage compressor (121, 122, 123) passes through the first low-stage oil separator (124) and flows out to the sixth connection pipe (36). In the first low-stage oil separator (124), oil is separated from the refrigerant discharged from each low-stage compressor (121, 122, 123). The separated oil is sucked into each low-stage oil separator (121, 122, 123) via the first low-stage oil return pipe (124a) by appropriately opening the second solenoid valve (SV2). .

  Similarly, the refrigerant flowing into the second booster circuit (160) is sucked into the low-stage compressors (161, 162, 163). The refrigerant compressed by the low-stage compressors (161, 162, 163) passes through the second low-stage oil separator (164) and flows out to the sixth connection pipe (36). In the second low-stage oil separator (164), oil is separated from the refrigerant discharged from each low-stage compressor (161, 162, 163). The separated oil is sucked into the low-stage oil separators (161, 162, 163) via the second low-stage oil return pipe (164a) by appropriately opening the seventh solenoid valve (SV7). .

  The refrigerant merged in the sixth connection pipe (36) passes through the four-way switching valve (48) and flows into the high stage suction pipe (58). This refrigerant is mixed with the refrigerant that has flowed out of the second heat transfer tube (46b) of the internal heat exchanger (46), and is sucked into each high stage compressor (121, 122, 123) and compressed.

<Defrost operation>
In the defrost operation of the refrigeration apparatus (10), a first individual defrost operation for defrosting the first cooling heat exchanger (102) and a second individual defrost operation for defrosting the second cooling heat exchanger (112) Is repeated.

  In the refrigeration apparatus (10), when the above cooling operation is continuously performed for a predetermined time or more, the cooling operation is shifted to the defrost operation. Specifically, when a timer provided in the controller (200) counts a predetermined set time, it is determined that the amount of frost formation in each cooling heat exchanger (102, 112) has increased, and the defrost operation is performed.

  In the defrost operation, first, a first individual defrost operation is performed. In the first individual defrost operation, the first cooling heat exchanger (102) is to be defrosted. Further, when this defrost operation is started, a pre-discharge operation for collecting the refrigerant accumulated in the second cooling heat exchanger (112) that is not to be defrosted in the first first individual defrost operation thereafter is performed. Is called.

《Pre-discharge operation》
In the preliminary discharge operation shown in FIG. 5, the four-way selector valve (48) is set to the first state, and the high-stage compressors (41, 42, 43) are in the operating state. Further, the outdoor expansion valve (47) is fully closed, and the opening degree of the supercooling side expansion valve (94) is adjusted. In the 1st utilization side circuit (100,120) corresponding to the 1st cooling heat exchanger (102) used as the defrost object by the 1st individual defrost operation mentioned below, the 1st indoor expansion valve (101) and the 3rd electric valve (146a) ) And the opening degree of the fourth electric valve (147a) are appropriately adjusted, and the sixth electromagnetic valve (SV6) is closed. In the first usage side circuit (100, 120), the low-stage compressors (121, 122, 123) are in an operating state. On the other hand, in the 2nd utilization side circuit (110,160) corresponding to the 2nd cooling heat exchanger (112) which becomes the object for defrosting by the 1st individual defrost operation, the 2nd indoor expansion valve (111), the 5th electric valve ( 186a) and the sixth motor-operated valve (187a) are fully closed, and the eleventh electromagnetic valve (SV11) is also closed. In the second usage side circuit (110, 160), the variable capacity type fourth low stage compressor (161) is in an operating state.

  In this pre-discharge operation, the refrigerant compressed by each high-stage compressor (41, 42, 43) is condensed by the outdoor heat exchanger (44) and then sent only to the first usage side circuit (100, 120) side. It is done. In the first usage side circuit (100, 120), the refrigerant decompressed by the first indoor expansion valve (101) evaporates in the first cooling heat exchanger (102). Therefore, in this pre-discharge operation, the air in the refrigeration showcase (14) is still continuously cooled. The refrigerant evaporated in the first cooling heat exchanger (102) is compressed by the low-stage compressors (121, 122, 123) of the first booster circuit (120) and flows out to the sixth connection pipe (36).

  On the other hand, in the second usage side circuit (110, 160), the refrigerant is sealed between the second indoor expansion valve (111) and the suction port of each low-stage compressor (161, 162, 163). When the fourth low-stage compressor (161) is driven in this state, the refrigerant accumulated in the second cooling heat exchanger (112) or the refrigerant sealed in the other pipes is reduced to the fourth low-pressure side compressor (161). It is sucked into the stage side compressor (161) and compressed. At this time, the pressure on the suction side of the fourth low-stage compressor (161) rapidly decreases. For this reason, even if the sealed refrigerant is condensed and liquefied, the refrigerant is decompressed and gasified. Therefore, the so-called liquid compression phenomenon that the liquid refrigerant is sucked into the fourth low-stage compressor (161) is avoided.

  The refrigerant discharged from the fourth low-stage compressor (161) passes through the second low-stage oil separator (164) and flows out to the sixth connection pipe (36). As described above, in the second usage side circuit (110, 160) that is not to be defrosted in the first individual defrosting operation, the refrigerant is discharged out of the system with the operation of the low-stage compressor (161), and the outdoor circuit. Collected to the (40) side. During the pre-discharge operation, this refrigerant is sent to the first cooling heat exchanger (102) and used for cooling the refrigeration showcase (14).

  In this preliminary discharge operation, the seventh solenoid valve (SV7) is appropriately opened, so that the oil recovered in the second low-stage oil separator (164) is transferred to the second low-stage oil return pipe. Returned to (164a). Further, at this time, the eighth solenoid valve (SV8) is opened, so that excess oil in the fourth low-stage compressor (161) passes through the fourth oil feed pipe (181). 6 is sent to the connecting pipe (36), and finally sucked into each high stage compressor (41, 42, 43). As described above, in this preliminary discharge operation, the oil in the low-stage compressor (161) of the second usage-side circuit (110, 160), which is not subject to defrosting in the first individual defrost operation, is compressed by each high-stage compression. The oil recovery operation sent to the machine (41, 42, 43) is also performed.

  In the pre-discharge operation, the operating capacity of the fourth low-stage compressor (161) is controlled according to the refrigerant temperature on the discharge side of each low-stage compressor (161, 162, 163) of the second usage side circuit (110, 160). . Specifically, for example, the fourth low-stage compressor (161) is controlled such that the operating frequency decreases as the temperature of the discharge refrigerant detected by the seventh discharge temperature sensor (191) increases.

  In the pre-discharge operation, the fourth low-stage compressor (161) stops when the temperature detected by the seventh discharge temperature sensor (191) is equal to or higher than a predetermined temperature. As a result, the pre-discharge operation is finished, and the first individual defrost operation is performed.

<First individual defrost operation>
In the first individual defrost operation shown in FIG. 6, the four-way selector valve (48) is set to the second state, and the high-stage compressors (41, 42, 43) are in the operating state. Further, the opening degrees of the outdoor expansion valve (47) and the supercooling side expansion valve (94) are adjusted. In the 1st utilization side circuit (100,120) corresponding to the 1st cooling heat exchanger (102) used as the defrost object by the 1st individual defrost operation, the 1st indoor expansion valve (101) will be in a full open state, and the 3rd electric valve (146a) and the fourth electric valve (147a) are fully closed, and the sixth electromagnetic valve (SV6) is opened. In the first usage side circuit (100, 120), the low-stage compressors (121, 122, 123) are stopped.

  On the other hand, in the 2nd utilization side circuit (110,160) corresponding to the 2nd cooling heat exchanger (112) which becomes the object for defrosting by the 1st individual defrost operation, the 2nd indoor expansion valve (111), the 5th electric valve ( 186a) and the sixth motor-operated valve (187a) are fully closed, and the eleventh electromagnetic valve (SV11) is closed. In the second usage side circuit (110, 160), the low-stage compressors (161, 162, 163) are stopped.

  In the first individual defrost operation, the refrigerant compressed by the high-stage compressors (41, 42, 43) flows out to the sixth connection pipe (36). The refrigerant that has flowed out into the sixth connection pipe (36) flows through the first booster circuit (120) and into the first low-stage oil separator (124). In the first low-stage oil separator (124), the refrigerant accumulated therein is pushed out and flows out to the first bypass pipe (145). The refrigerant flowing through the first bypass pipe (145) flows into the first refrigeration circuit (100) via the first low-stage suction pipe (138).

  The refrigerant flowing into the first refrigeration circuit (100) flows through the first cooling heat exchanger (102). In the first cooling heat exchanger (102), frost on the surface is heated and melted from the inside, while the refrigerant is condensed by taking heat of fusion to the frost. The refrigerant condensed in the first cooling heat exchanger (102) flows through the heating pipe part (33a) of the third communication pipe (33) after passing through the fully opened first indoor expansion valve (101). As a result, the inside of the drain pan (104) is heated by the refrigerant, and frost and ice blocks in the drain pan (104) are melted. The refrigerant that has passed through the third communication pipe (33) is cooled by the supercooling heat exchanger (91) and flows into the refrigerant reservoir (81).

  Here, the refrigerant reservoir (81) stores a refrigerant for increasing the amount of refrigerant used for defrosting of each cooling heat exchanger (102, 112) during the defrost operation. In other words, during the defrost operation, the refrigerant may stagnate in each cooling heat exchanger (102, 112), and the amount of refrigerant used for defrosting may be insufficient, but the refrigerant reservoir (81) There is enough refrigerant to make up for the shortage. For this reason, when the stagnation of the refrigerant occurs in the cooling heat exchanger (102, 112), the refrigerant corresponding to the amount of the stagnation refrigerant appropriately flows out from the refrigerant reservoir (81) to the fourth liquid pipe (82), and the refrigerant circuit The refrigerant inside is replenished.

  The refrigerant flowing out of the refrigerant reservoir (81) is further cooled by the internal heat exchanger (46) and then depressurized by the outdoor expansion valve (47). The refrigerant decompressed by the outdoor expansion valve (47) condenses in the outdoor heat exchanger (44) and is sucked into the high stage compressors (41, 42, 43).

  On the other hand, in the second usage side circuit (110, 160), the second indoor expansion valve (111), the eleventh electromagnetic valve (SV11), the fifth electric valve (186a), and the sixth electric valve (187a) are closed. It has become. For this reason, a refrigerant | coolant is not sent to a 2nd utilization side circuit (110,160), and the 2nd cooling heat exchanger (112) except the defrost object of a 1st separate defrost operation | movement becomes a dormant state.

  Such a first individual defrosting operation ends before a predetermined amount of liquid refrigerant accumulates in the first cooling heat exchanger (102). Specifically, when the first individual defrosting operation is continuously performed, the liquid refrigerant accumulates in the first cooling heat exchanger (102), and therefore flows out of the first cooling heat exchanger (102). The degree of supercooling of the refrigerant increases. In the first individual defrosting operation, for example, the condensing temperature of the first cooling heat exchanger (102) obtained from the detection values of the first higher stage pressure sensor (74) and the first refrigerant temperature sensor (105), and the second refrigerant The degree of supercooling is calculated from the difference from the temperature of the refrigerant detected by the temperature sensor (106). Then, when the calculated degree of supercooling is equal to or higher than a predetermined temperature (for example, 5 ° C.), the first individual defrosting operation is finished.

  After the end of the first individual defrost operation, the next individual defrost operation is performed so as to change the cooling heat exchanger (102, 112) to be defrosted. Specifically, after the completion of the first individual defrost operation, the defrost target is changed from the first cooling heat exchanger (102) to the second cooling heat exchanger (112), and the second individual defrost operation is performed. Is called.

  By the way, when the first individual defrosting operation described above is performed, the refrigerant remains in the first cooling heat exchanger (102) and the pipes before and after the first cooling heat exchanger (102). If the second individual defrosting operation is performed immediately from this state, there is a possibility that a sufficient amount of refrigerant used for defrosting the second cooling heat exchanger (112) cannot be secured. Therefore, in the refrigeration apparatus (10) of the present embodiment, before the second individual defrost operation, the exhaust for discharging the refrigerant in the first cooling heat exchanger (102) that is not the defrost target of the second individual defrost operation. The operation (first discharge operation) is performed in the same manner as the above-described preliminary discharge operation.

<First discharge operation>
In the first discharge operation shown in FIG. 7, the four-way selector valve (48) is set to the second state, and the high-stage compressors (41, 42, 43) are in the operating state. Further, the opening degrees of the outdoor expansion valve (47) and the supercooling side expansion valve (94) are adjusted. In the second usage side circuit (110, 160) corresponding to the second cooling heat exchanger (112) to be defrosted in the second individual defrosting operation, the second indoor expansion valve (111) is fully opened, and the fifth electric valve (186a) and the sixth motor-operated valve (187a) are closed, and the eleventh solenoid valve (SV11) is opened. In the second usage side circuit (110, 160), the low-stage compressors (161, 162, 163) are stopped.

  On the other hand, in the 1st utilization side circuit (100,120) corresponding to the 1st cooling heat exchanger (102) used as the object of defrosting by the 2nd individual defrost operation, the 1st indoor expansion valve (101), the 3rd electric valve ( 146a) and the fourth motor-operated valve (147a) are fully closed, and the sixth solenoid valve (SV6) is also closed. In the first usage side circuit (110, 160), the variable capacity type first low stage compressor (121) is in an operating state.

  In the first discharge operation, the refrigerant compressed by the high-stage compressors (41, 42, 43) flows out to the sixth connection pipe (36). The refrigerant flowing through the sixth connection pipe (36) flows through the second booster circuit (160) and flows into the second low-stage oil separator (164). In the second low-stage oil separator (164), the refrigerant accumulated in the second low-stage oil separator (164) flows out to the second bypass pipe (185) so as to be pushed out. The refrigerant flowing through the second bypass pipe (185) flows into the second refrigeration circuit (110) via the second low-stage suction pipe (178).

  The refrigerant flowing into the second refrigeration circuit (110) flows through the second cooling heat exchanger (112). In the second cooling heat exchanger (112), the frost on the surface is heated from the inside to be melted, and the refrigerant is condensed by taking heat of fusion to the frost. The refrigerant condensed in the second cooling heat exchanger (112) flows through the heating pipe portion (33a) of the third communication pipe (33) after passing through the fully opened second indoor expansion valve (111). As a result, the inside of the drain pan (104) is heated by the refrigerant, and frost and ice blocks in the drain pan (104) are melted. The subsequent flow of the refrigerant is the same as the first individual defrosting operation, and thus the description thereof is omitted.

  On the other hand, in the first usage side circuit (100, 120), the refrigerant is sealed from the first indoor expansion valve (101) to the suction port of each low-stage compressor (141, 142, 143). When the first low-stage compressor (121) is driven in this state, the refrigerant accumulated in the first cooling heat exchanger (102) or the refrigerant sealed in the other pipes becomes the first low-pressure compressor (121). It is sucked into the stage side compressor (141) and compressed. At this time, since the pressure on the suction side of the first low-stage compressor (121) suddenly decreases and the refrigerant is gasified, the liquid compression phenomenon in the first low-stage compressor (121) is avoided. Is done.

  The refrigerant compressed by the first low-stage compressor (121) passes through the first low-stage oil separator (124) and flows out to the sixth connection pipe (36). This refrigerant is mixed with the refrigerant discharged from each high-stage compressor (41, 42, 43) and sent to the second usage side circuit (110, 160). That is, the refrigerant discharged from the first use side circuit (100, 120) is used for defrosting the second cooling heat exchanger (112). Here, the input heat of the first low-stage compressor (121) is given to the refrigerant discharged from the first usage-side circuit (100, 120). For this reason, the defrosting capability of the second cooling heat exchanger (112) is improved.

  In the first discharge operation, the second solenoid valve (SV2) and the third solenoid valve (SV3) are appropriately opened in the same manner as in the above-described preliminary discharge operation. As a result, an oil recovery operation is performed in which surplus oil in the first low-stage compressor (121) is sent to the high-stage compressor (41, 42, 43) side.

  The first discharge operation is terminated when the temperature detected by the fourth discharge temperature sensor (151) is equal to or higher than a predetermined temperature, and the second individual defrost operation is performed in the same manner as the above-described pre-discharge operation.

《Second individual defrost operation》
In the second individual defrost operation shown in FIG. 8, the four-way selector valve (48) is set to the second state, and the high-stage compressors (41, 42, 43) are in the operating state. Further, the opening degrees of the outdoor expansion valve (47) and the supercooling side expansion valve (94) are adjusted. In the second usage side circuit (110, 160) corresponding to the second cooling heat exchanger (112) to be defrosted in the second individual defrosting operation, the second indoor expansion valve (111) is fully opened, and the fifth electric valve (186a) and the sixth electric valve (187a) are fully closed, and the eleventh electromagnetic valve (SV11) is opened. In the second usage side circuit (110, 160), the low-stage compressors (161, 162, 163) are stopped.

  On the other hand, in the 1st utilization side circuit (100,120) corresponding to the 1st cooling heat exchanger (102) used as the object of defrosting by the 2nd individual defrost operation, the 1st indoor expansion valve (101), the 3rd electric valve ( 146a) and the fourth motor-operated valve (147a) are fully closed, and the sixth solenoid valve (SV6) is also closed. In the first usage side circuit (100, 120), the low-stage compressors (121, 122, 123) are stopped.

  In the second individual defrosting operation, the refrigerant compressed by each high stage compressor (41, 42, 43) flows out to the sixth connection pipe (36). The refrigerant flowing through the sixth connection pipe (36) flows through the second booster circuit (160) and flows into the second low-stage oil separator (164). In the second low-stage oil separator (164), the refrigerant accumulated in the second low-stage oil separator (164) flows out to the second bypass pipe (185) so as to be pushed out. The refrigerant flowing through the second bypass pipe (185) flows into the second refrigeration circuit (110) via the second low-stage suction pipe (178).

  In the second refrigeration circuit (110), the defrosting of the second cooling heat exchanger (112) is performed in the same manner as the first individual defrost operation described above. The refrigerant that has flowed out of the second cooling heat exchanger (112) is also used for heating the drain pan (104). The subsequent flow of the refrigerant is the same as the first individual defrosting operation, and thus the description thereof is omitted.

  Such a second individual defrosting operation ends before a predetermined amount of liquid refrigerant accumulates in the second cooling heat exchanger (112). Specifically, in the second individual defrosting operation, for example, the degree of supercooling is determined from the difference between the refrigerant temperature detected by the third refrigerant temperature sensor (115) and the refrigerant temperature detected by the fourth refrigerant temperature sensor (116). Calculated. Then, when the calculated degree of supercooling is equal to or higher than a predetermined temperature (for example, 5 ° C.), the second individual defrosting operation is finished.

  After the end of the second individual defrost operation, the first individual defrost operation is performed again. Prior to the first individual defrosting operation, an operation for discharging the refrigerant in the second cooling heat exchanger (112) (second discharging operation) is performed in the same manner as the first discharging operation described above.

<< Second discharge operation >>
In the second discharge operation shown in FIG. 9, the four-way selector valve (48) is set to the second state, and the high-stage compressors (41, 42, 43) are in the operating state. Further, the opening degrees of the outdoor expansion valve (47) and the supercooling side expansion valve (94) are adjusted. In the 1st utilization side circuit (100,120) corresponding to the 1st cooling heat exchanger (102) used as the defrost object by the 1st individual defrost operation, the 1st indoor expansion valve (101) will be in a full open state, and the 3rd electric valve (146a) and the fourth motor-operated valve (147a) are closed, and the sixth solenoid valve (SV6) is opened. In the first usage side circuit (100, 120), the low-stage compressors (121, 122, 123) are stopped.

  On the other hand, in the 2nd utilization side circuit (110,160) corresponding to the 2nd cooling heat exchanger (112) which becomes the object for defrosting by the 1st individual defrost operation, the 2nd indoor expansion valve (111), the 5th electric valve ( 186a) and the sixth motor-operated valve (187a) are fully closed, and the eleventh electromagnetic valve (SV11) is also closed. In the second usage side circuit (110, 160), the variable capacity type fourth low stage compressor (161) is in an operating state.

  In the second discharge operation, the refrigerant in the second usage side circuit (110, 160) is discharged out of the system in the same manner as the first discharge operation described above. This refrigerant is sent to the first cooling heat exchanger (102) together with the refrigerant discharged from each high-stage compressor (41, 42, 43) and used for defrosting.

  As described above, during the defrost operation, after the pre-discharge operation, the first individual defrost operation → the first discharge operation → the second individual defrost operation → the second discharge operation → the first individual defrost operation →. Each operation is repeated. The defrosting operation ends when a timer provided in the controller (200) counts a predetermined set time, and then the cooling operation is resumed.

-Effect of the embodiment-
In the above-described embodiment, in the defrost operation, the first individual defrost operation and the second individual defrost operation are sequentially performed so that the cooling heat exchangers (102, 112) to be defrosted are alternately changed. For this reason, according to the said embodiment, compared with the case where two cooling heat exchangers (102,112) are defrosted simultaneously as a condenser, the quantity of the refrigerant | coolant which accumulates in a cooling heat exchanger (102,112) is reduced. Less. Therefore, in each individual defrost operation, the amount of refrigerant used for defrosting the cooling heat exchanger (102, 112) can be sufficiently secured, so that the efficiency of the defrost operation can be increased.

  Moreover, in the said embodiment, before performing each individual defrost operation | movement, the discharge operation | movement which sends the refrigerant | coolant in the cooling heat exchanger (102,112) used as the defrost object to the cooling heat exchanger (102,112) side which is a defrost object is performed. Like to do. For this reason, according to the above-described embodiment, in the subsequent individual defrosting operation, the refrigerant in the cooling heat exchanger (102, 112) that is in a dormant state is used for defrosting the cooling heat exchanger (102, 112) that is to be defrosted. Therefore, it is possible to reliably avoid the refrigerant shortage due to the stagnation of the refrigerant.

  In the first discharge operation and the second discharge operation of the above-described embodiment, the refrigerant compressed by each low-stage compressor (121, 161) is sent to the cooling heat exchanger (102, 112) to be defrosted. For this reason, since the input heat of each low stage side compressor (121,161) can be used for defrosting of the cooling heat exchanger (102,112), the defrosting capacity of the cooling heat exchanger (102,112) is improved. Can do.

  Further, in each discharge operation, the indoor expansion valves (101, 111) of the use side circuit (100, 120, 110, 160) that are not to be defrosted are fully closed. For this reason, the refrigerant can be sealed between the indoor expansion valve (101, 111) and the suction port of the low-stage compressor (121, 122, 123, 161, 162, 163), and this refrigerant is sent to the cooling heat exchanger (102) to be defrosted. Can send. Further, when the low-stage compressors (121, 161) are operated in this manner, the suction-side refrigerant is decompressed and gasified. Therefore, it is possible to avoid the occurrence of the liquid compression phenomenon in each of the low stage compressors (121, 161).

  Furthermore, in the above embodiment, one end of each bypass pipe (145, 185) is connected to each low-stage oil separator (124, 164). Therefore, in the defrost operation, the refrigerant accumulated in each low-stage oil separator (124, 164) can also be sent to the cooling heat exchanger (102, 112) to be defrosted via the bypass pipe (145, 185). Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of each cooling heat exchanger (102, 112). In particular, since one end of the bypass pipe (145, 185) is connected to the bottom of the low-stage oil separator (124, 164), the liquid refrigerant or the like accumulated in the low-stage oil separator (124, 164) can also be quickly removed. ).

  Moreover, in the said embodiment, each cooling heat exchanger (102,112) is comprised so that a fin may be shared. For this reason, in each individual defrost operation, the defrosting of the dormant cooling heat exchanger (102, 112) can be performed using the heat of the refrigerant in the condenser cooling heat exchanger (102, 112). Therefore, it is possible to shorten the time required for defrosting each cooling heat exchanger (102, 112).

  In the defrost operation of the above embodiment, the defrost target is changed when the degree of supercooling of the refrigerant flowing out from the cooling heat exchanger (102, 112) to be defrosted exceeds a predetermined temperature. For this reason, the stagnation of the refrigerant in each cooling heat exchanger (102, 112) can be avoided in advance. Therefore, it is possible to sufficiently secure the amount of refrigerant used for defrosting of each cooling heat exchanger (102, 112).

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In the above embodiment, the individual defrosting operation is performed in the refrigeration apparatus capable of the two-stage compression refrigeration cycle. However, in a refrigeration apparatus that performs a single-stage compression refrigeration cycle, an individual defrost operation may be performed in each cooling heat exchanger.

  In the above embodiment, two cooling heat exchangers (102, 112) are provided, and individual defrosting operations are alternately performed by these cooling heat exchangers (102, 112). However, three or more cooling heat exchangers may be provided, and at least one of the cooling heat exchangers may be a defrost target, and the individual defrost operation may be performed by changing the defrost target in a predetermined order. .

  Moreover, in the said embodiment, each cooling heat exchanger (102,112) is provided in the same warehouse. However, each cooling heat exchanger (102, 112) may be installed in a different refrigeration showcase, and the individual defrosting operation may be performed by each cooling heat exchanger (102, 112).

  In each discharge operation of the above embodiment, when the temperature of the refrigerant discharged from the low-stage compressor (121, 161) becomes a predetermined temperature or higher, the low-stage compressor (121, 161) is stopped. However, other than this, for example, when the pressure on the suction side of the low-stage compressor (121, 161) becomes a predetermined pressure or less, the low-stage compressor (121, 161) may be stopped.

  Moreover, in the said embodiment, when the supercooling degree of the cooling heat exchanger (102,112) used as a defrost object becomes more than predetermined temperature, it will transfer to the following separate defrost operation so that a defrost object may be changed. . However, the temperature of the refrigerant flowing out from the cooling heat exchanger (102, 112) is detected by each refrigerant temperature sensor (105, 115), and when this temperature exceeds a predetermined temperature, the defrost target is changed and the next individual defrost operation is performed. You may do it. Further, for example, the pressure on the high-pressure side of the outdoor circuit (40) may be detected by the high-stage high-pressure sensor (74), and when this pressure exceeds a predetermined pressure, the next individual defrosting operation may be performed.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention relates to a refrigeration apparatus including a plurality of usage-side heat exchangers, and particularly useful for a refrigeration apparatus capable of defrosting operation that performs a refrigeration cycle for defrosting the plurality of usage-side heat exchangers. is there.

It is a piping system diagram showing a schematic configuration of a refrigeration apparatus according to an embodiment. It is the schematic block diagram which showed typically the cooling heat exchanger of the freezing apparatus which concerns on embodiment. It is a piping system figure showing the neighborhood of the low stage side oil separator of the refrigerating device concerning an embodiment. It is a piping system diagram which shows the flow of the refrigerant | coolant at the time of the cooling operation of the freezing apparatus which concerns on embodiment. It is a piping system diagram which shows the flow of the refrigerant | coolant of the prior discharge operation | movement of the freezing apparatus which concerns on embodiment. It is a piping system diagram which shows the flow of the refrigerant | coolant of the 1st separate defrost operation | movement of the freezing apparatus which concerns on embodiment. It is a piping system figure showing the flow of the refrigerant of the 1st discharge operation of the refrigerating device concerning an embodiment. It is a piping system diagram which shows the flow of the refrigerant | coolant of the 2nd separate defrost operation | movement of the freezing apparatus which concerns on embodiment. It is a piping system diagram which shows the flow of the refrigerant | coolant of the 2nd discharge operation of the freezing apparatus which concerns on embodiment.

Explanation of symbols

10 Refrigeration equipment
40 Outdoor circuit (heat source side circuit)
41,42,43 High stage compressor (compressor)
44 Heat source side heat exchanger (outdoor heat exchanger)
100,120 First refrigeration circuit, first booster circuit (first use side circuit)
110,160 Second refrigeration circuit, second booster circuit (second use side circuit)
101,111 Indoor expansion valve (expansion valve)
102,112 Cooling heat exchanger (use side heat exchanger)
121,161 Low stage compressor
124,164 Low stage oil separator (oil separator)
145,185 Bypass pipe
SV6, SV11 Solenoid valve (open / close valve)

Claims (11)

A heat source side circuit (40) having a compressor (41, 42, 43) and a heat source side heat exchanger (44), each having a use side heat exchanger (102, 112) and parallel to the heat source side circuit (40) A plurality of use side circuits (100, 120, 110, 160) connected to
The heat source side heat exchanger (44) serves as a condenser, the use side heat exchanger (102, 112) serves as an evaporator, and a cooling operation for performing a refrigeration cycle, and the use side heat exchanger (102, 112) serves as a condenser, The heat source side heat exchanger (44) is a refrigeration apparatus capable of switching between defrost operation and performing a refrigeration cycle that serves as an evaporator,
In the above defrost operation, the individual defrost operation in which a part of the plurality of use side heat exchangers (102, 112) is a condenser and the rest is in a dormant state, all the use side heat exchangers (102, 112) are once condensers. The use-side heat exchanger (102, 112) that becomes the condenser is changed every time so that the refrigerant is discharged, and the refrigerant is discharged from the use-side heat exchanger (102, 112) that is in a dormant state by the individual defrost operation. A refrigeration apparatus that performs a discharging operation. In claim 1,
The heat source side circuit (40) is provided with a high stage compressor (41, 42, 43), while each of the use side circuits (100, 120, 110, 160) is provided with a low stage compressor (121, 122, 123, 161, 162, 163). ,
In the cooling operation, the high-stage compressor (41, 42, 43) and the low-stage compressor (121, 122, 123, 161, 162, 163) are operated to perform a two-stage compression refrigeration cycle. In the defrost operation, the high-stage compressor (41, 42, 43) is configured to perform a refrigeration cycle using only the use side heat exchanger (102, 112) to be defrosted as a condenser,
In the above discharge operation, by operating the low-stage compressor (121, 122, 123, 161, 162, 163) of the utilization side circuit (100, 120, 110, 160) corresponding to the utilization side heat exchanger (102, 112) that is not defrosted, the utilization side heat that is not defrosted is operated. A refrigerating apparatus, wherein the refrigerant in the exchanger (102, 112) is sent to the use side heat exchanger (102, 112) to be defrosted. In claim 2,
Each of the use side circuits (100, 120, 110, 160) is provided with an expansion valve (101, 111) that depressurizes the refrigerant on the inflow side of the use side heat exchanger (102, 112) during the cooling operation,
In the individual defrosting operation, the expansion valve (101,111) of the utilization side circuit (100,120,110,160) corresponding to the utilization side heat exchanger (102,112) to be defrosted is opened, and the utilization side heat exchanger (102,112) not to be defrosted is opened. The expansion valve (101, 111) of the use side circuit (100, 120, 110, 160) corresponding to is fully closed. In claim 3,
In the discharging operation, the expansion valve (101, 111) of the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) that is not to be defrosted is fully closed. In any one of Claim 2 thru | or 4,
Each of the use side circuits (100, 120, 110, 160) includes a bypass pipe (SV6, SV11) that connects the suction side and the discharge side of the low stage compressor (121, 122, 123, 161, 162, 163) and has an open / close valve (SV6, SV11) that is closed during the cooling operation. 145, 185) are provided,
In the above individual defrosting operation, the open / close valve (SV6, SV11) of the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) to be defrosted is opened, and the use side heat exchanger (non-defrost target to be used) 102, 112), the open / close valves (SV6, SV11) of the use side circuit (100, 120, 110, 160) corresponding to the refrigeration apparatus are closed. In claim 5,
In the discharging operation, the open / close valve (SV6, SV11) of the use side circuit (100, 120, 110, 160) corresponding to the use side heat exchanger (102, 112) that is not to be defrosted is closed. In claim 5,
Each of the use side circuits (100, 120, 110, 160) includes a container-like oil separator (124, 164) for sucking oil in the refrigerant discharged from each low stage compressor (121, 122, 123, 161, 162, 163) into each low stage compressor (121, 122, 123, 161, 162, 163). Are provided,
One end of each bypass pipe (145, 185) is connected to each oil separator (124, 164). In claim 7,
One end of each bypass pipe (145, 185) is connected to the bottom of each oil separator (124, 164). In any one of claims 1 to 8,
Each said use side heat exchanger (102,112) is provided in the same warehouse, and is comprised so that each may share the same fin (102a), The refrigeration apparatus characterized by the above-mentioned. In any one of Claims 1 thru | or 9,
In the defrosting operation, the defrosting target for the individual defrosting operation is changed when the degree of supercooling of the refrigerant flowing out of the use side heat exchanger (102, 112) to be defrosted exceeds a predetermined temperature. . In any one of Claims 1 thru | or 9,
In the defrosting operation, the defrosting target of the individual defrosting operation is changed when the temperature of the refrigerant flowing out of the use side heat exchanger (102, 112) to be defrosted exceeds a predetermined temperature.

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