JP2013210155A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating device suppressing a manufacturing cost and preventing control from becoming complicated.SOLUTION: A refrigerating device 10 has a multi-stage compressing mechanism 20 constituting by connecting a plurality of compressing parts in series, a heat source side main heat exchanging part 44 cooling refrigerant discharged from the compression part of the backmost side during cooling operation and becoming an evaporator during warming operation, a heat source side sub heat exchanging part 41 cooling refrigerant discharge from a front stage compressing section and sucked by the next rear stage compressing section during cooling operation and becoming an evaporator during heating operation, a using side heat exchanging section 12a functioning as an evaporator during cooling operation and functioning as a radiator during warming operation, a first expanding mechanisms 70, 52 decompressing refrigerant sent from the heat source side main heat exchanging part to the using side heat exchanging part during coding operation and sent in an opposite direction during warming operation, a first check valve 51b stopping the flow of refrigerant from the heat source side sub heat exchanging part to the using side heat exchanging part during cooling operation and allowing the opposite flow during warming operation, and a first capillary tube 51a decompressing refrigerant sent from the using side heat exchanging part to the heat source side sub heat exchanging the part during warming operation.

Description

  The present invention relates to a refrigeration apparatus.

  A conventional refrigeration apparatus having a refrigerant circuit configured to be able to switch between a cooling operation and a heating operation and performing a multistage compression refrigeration cycle is disclosed in Japanese Patent Application Laid-Open No. 2009-229051. There is such an air conditioner. The air conditioner mainly includes a multi-stage mechanism having a plurality of compression units connected in series, a use side heat exchange unit, and a heat source side heat exchange unit. The heat source side heat exchange part includes a heat source side main heat exchange part and a heat source side sub heat exchange part. The heat source side main exchange unit functions as a radiator that radiates high-pressure refrigerant during cooling, and functions as an evaporator that evaporates low-pressure refrigerant during heating. The heat source side sub heat exchange unit cools the refrigerant that is discharged from the compression unit on the front stage among the plurality of compression units and sucked into the compression unit on the rear stage during cooling, and functions as an evaporator during heating. . Here, in the refrigeration apparatus, it is necessary to adjust the flow rate of the refrigerant flowing through the heat source side main heat exchange unit and the heat source side sub heat exchange unit. Adjustment of the flow rate of the refrigerant is performed using a motor valve that can be fully closed.

  However, providing motorized valves corresponding to the number of heat source side main heat exchanging units and heat source side sub heat exchanging units increases the cost and complicates the control of the motorized valves.

  An object of the present invention is to reduce manufacturing cost and reduce control complexity in a refrigeration apparatus including a heat source side main heat exchange unit and a heat source side sub heat exchange unit.

  A refrigeration apparatus according to a first aspect of the present invention includes a multistage compression mechanism, a heat source side main heat exchange unit, a heat source side sub heat exchange unit, a use side heat exchange unit, a first expansion mechanism, and a first reverse mechanism. A stop valve and a first capillary tube are provided. In the multistage compression mechanism, a plurality of compression units are connected in series. The heat source side main heat exchanging unit cools the refrigerant discharged from the most downstream side compression unit among the plurality of compression units during the cooling operation, and functions as a refrigerant evaporator during the heating operation. The heat source side sub heat exchanging unit cools the refrigerant discharged from the compression unit on the front stage among the plurality of compression units during the cooling operation and sucked into the compression unit on the next rear stage, and functions as a refrigerant evaporator during the heating operation To do. The use-side heat exchange unit functions as an evaporator that evaporates a low-pressure refrigerant during cooling, and functions as a radiator that radiates heat from the high-pressure refrigerant during heating. The first expansion mechanism depressurizes the refrigerant sent from the heat source side main heat exchange unit to the use side heat exchange unit during cooling, and depressurizes the refrigerant sent from the use side heat exchange unit to the heat source side main heat exchange unit during heating. The first check valve stops the flow of refrigerant from the heat source side sub heat exchange unit to the use side heat exchange unit during cooling, and allows the refrigerant flow from the use side heat exchange unit to the heat source side sub heat exchange unit during heating. To do. The first capillary tube depressurizes the refrigerant sent from the use side heat exchange unit to the heat source side sub heat exchange unit during heating.

  In this refrigeration apparatus, the refrigerant flowing between the heat source side main heat exchange part and the use side heat exchange part is depressurized by the first expansion mechanism, and flows between the heat source side sub heat exchange part and the use side heat exchange part. The refrigerant is drift-adjusted by the first check valve and the first capillary tube. Thereby, the manufacturing cost of a freezing apparatus can be held down. Moreover, since the number of motor-operated valves can be suppressed, control complexity can be suppressed.

  A refrigeration apparatus according to a second aspect of the present invention is the refrigeration apparatus according to the first aspect, wherein the multistage compression mechanism includes a low-stage compression section on the front stage side, a middle-stage compression section higher than the low-stage compression section, and And the highest stage compression section on the rearmost stage side. The heat source side main heat exchange unit cools the refrigerant discharged from the high-stage compression unit. In addition, the heat source side sub heat exchange unit includes a first heat source side sub heat exchange unit and a second heat source side sub heat exchange unit. The first heat source side sub heat exchange unit cools the refrigerant discharged from the low-stage compression unit. The second heat source side sub heat exchange unit cools the refrigerant discharged from the middle stage compression unit. The first check valve and the first capillary tube are arranged on the refrigerant inflow side during heating for each of the first heat source side sub heat exchange part and the second heat source side sub heat exchange part. Furthermore, the refrigeration apparatus includes a suction pipe and a switching mechanism. The suction pipe supplies the refrigerant from between the first check valve and the first capillary tube and the first heat source side sub heat exchange part or the second heat source side sub heat exchange part to the middle stage compression part or the high stage compression part. return. During the cooling operation, the switching mechanism sends the refrigerant from the heat source side main heat exchanger to the use side heat exchanger, and during the heating operation, from the use side heat exchanger to the heat source side main heat exchanger and the heat source side sub heat exchanger. The state switches so that the refrigerant is sent.

  The refrigeration apparatus includes a multi-stage compression mechanism including a low-stage compression section, a middle-stage compression section, and a high-stage compression section, and a heat source side sub heat exchange section including first and second heat source side sub heat exchange sections. . The refrigeration apparatus includes a suction pipe and a switching mechanism. As a result, the refrigerant compressed by the low-stage compression section passes through the first heat source side sub heat exchange section, and is then returned to the middle-stage compression section before the first capillary tube and the first check valve. In addition, the refrigerant compressed by the middle stage compression unit passes through the second heat source side sub heat exchange unit, and then is returned to the high stage compression unit before the first capillary tube and the first check valve. By adopting such a configuration, even when the number of heat source side sub heat exchange units is increased, control complexity can be suppressed, and the manufacturing cost of the refrigeration apparatus can be further suppressed.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the second aspect, further comprising a second expansion mechanism and a branch path. A 2nd expansion mechanism decompresses the refrigerant | coolant sent toward the heat-source side sub heat exchange part from the utilization side heat exchange part at the time of heating. The branch path branches the refrigerant depressurized by the second expansion mechanism into each of the first heat source side sub heat exchange unit and the second heat source side sub heat exchange unit.

  This refrigeration apparatus includes a second expansion mechanism with respect to the plurality of heat source side sub heat exchange units, and causes the refrigerant decompressed by the second expansion mechanism to branch through the branch path. Further, the branched refrigerant is decompressed through the first capillary tube and sent to each heat source side sub heat exchange section. Thereby, the pressure adjustment of the refrigerant | coolant sent toward a heat-source side sub heat exchange part can be performed effectively.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising a second check valve, a second capillary tube, and a branch path. The second check valve stops the flow of the refrigerant from the heat source side main heat exchange unit to the use side heat exchange unit during cooling, and allows the refrigerant flow from the use side heat exchange unit to the heat source side main heat exchange unit during heating. To do. A 2nd capillary tube decompresses the refrigerant | coolant sent to the heat source side main heat exchange part from the utilization side heat exchange part at the time of heating. The branch path branches the refrigerant decompressed by the first expansion mechanism to each of the heat source side main heat exchange unit and the heat source side sub heat exchange unit.

  In this refrigeration apparatus, the refrigerant decompressed by one first expansion mechanism is sent to both the heat source side main heat exchange unit and the heat source side sub heat exchange unit. The refrigerant decompressed by the first expansion mechanism is branched by the branch path. The branched refrigerant is sent to the heat source side sub heat exchange unit through the first capillary tube, and is sent to the heat source side main heat exchange unit through the second capillary tube. Thereby, the cost of a freezing apparatus can be suppressed further.

  In the refrigeration apparatus according to the first aspect of the present invention, the manufacturing cost of the refrigeration apparatus can be suppressed. Moreover, since the number of motor-operated valves can be suppressed, control complexity can be suppressed.

  In the refrigeration apparatus according to the second aspect of the present invention, even when the number of heat source side sub heat exchange units is increased, control complexity can be suppressed, and the manufacturing cost of the refrigeration apparatus can be further suppressed. it can.

  In the refrigeration apparatus according to the third aspect of the present invention, it is possible to effectively adjust the pressure of the refrigerant to be sent toward the heat source side sub heat exchange unit.

  In the refrigeration apparatus according to the fourth aspect of the present invention, the cost of the refrigeration apparatus can be further reduced.

It is a schematic block diagram at the time of air_conditionaing | cooling operation of the air conditioning apparatus which concerns on one Embodiment of this invention. FIG. 2 is a pressure-enthalpy diagram of a refrigeration cycle during the cooling operation of FIG. 1. It is a schematic block diagram at the time of the heating operation of an air conditioning apparatus. It is a pressure-enthalpy diagram of the refrigerating cycle at the time of heating operation of FIG. It is a schematic block diagram at the time of the cooling operation of the air conditioning apparatus which concerns on the modification A. It is a schematic block diagram at the time of the heating operation of the air conditioning apparatus which concerns on the modification A. It is a schematic block diagram at the time of air_conditionaing | cooling operation of the air conditioning apparatus which concerns on the modification B. FIG. 8 is a pressure-enthalpy diagram of the refrigeration cycle during the cooling operation of FIG. 7. It is a schematic block diagram at the time of the heating operation of the air conditioning apparatus which concerns on the modification B. FIG. 10 is a pressure-enthalpy diagram of the refrigeration cycle during the cooling operation of FIG. 9. It is a schematic block diagram at the time of the cooling operation of the air conditioning apparatus which concerns on the modification C. It is a schematic block diagram at the time of the heating operation of the air conditioning apparatus which concerns on the modification C. It is a schematic block diagram at the time of the cooling operation of the air conditioning apparatus which concerns on the modification D. It is a schematic block diagram at the time of the heating operation of the air conditioning apparatus which concerns on the modification D. It is a schematic block diagram at the time of the cooling operation of the air conditioning apparatus which concerns on the modification E.

1. First Embodiment An air conditioner 10 that is a refrigeration apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

(1) Configuration of Air Conditioner FIG. 1 and FIG. 3 are schematic configuration diagrams of the air conditioner 10. The air conditioning apparatus 10 is a refrigeration apparatus that performs a two-stage compression refrigeration cycle using a supercritical carbon dioxide refrigerant. The air conditioner 10 is an apparatus in which an outdoor unit 11 that is a heat source unit and a plurality of indoor units 12 that are utilization units are connected by a communication refrigerant pipe 14, and a refrigerant that switches between a cooling operation cycle and a heating operation cycle. It has a circuit. FIG. 1 shows the flow of the refrigerant circulating in the refrigerant circuit during the cooling operation. FIG. 3 shows the flow of the refrigerant circulating in the refrigerant circuit during the heating operation. In FIG. 1 and FIG. 3, the arrow shown along piping of a refrigerant circuit represents the flow of the refrigerant.

  The refrigerant circuit of the air conditioner 10 mainly includes the two-stage compressor 20, the first and second switching mechanisms 31, 32, the outdoor heat exchanger 40, the first capillary tube 51a, the first check valve 51b, and the first outdoor. Motorized valve 52, bridge circuit 55, economizer heat exchanger 61, internal heat exchanger 62, expansion mechanism 70, receiver 80, supercooling heat exchanger 90, indoor heat exchanger 12a, indoor motorized valve 12b, and control unit (not shown) Z). The outdoor heat exchanger 40 includes a first sub heat exchange unit 41 and a main heat exchange unit 44 arranged in parallel.

  Hereinafter, each component of the refrigerant circuit will be described in detail.

(1-1) Two-stage compressor The two-stage compressor 20 is a hermetically sealed type in which a low-stage compressor 21, a high-stage compressor 22, and a compressor drive motor (not shown) are housed in a hermetic container. It is a compressor. A compressor drive motor drives the two compression parts 21 and 22 via a drive shaft. That is, the two-stage compressor 20 has a uniaxial two-stage compression structure in which two compression units 21 and 22 are coupled to a single drive shaft. In the two-stage compressor 20, the low-stage compressor 21 and the high-stage compressor 22 are connected in series in this order. The low-stage compression unit 21 sucks the refrigerant from the first suction pipe 21a and discharges the refrigerant to the first discharge pipe 21b. The high-stage compression unit 22 sucks the refrigerant from the second suction pipe 22a and discharges the refrigerant to the second discharge pipe 22b.

  The low-stage compression unit 21 is a compression mechanism at the lowest stage (frontmost stage), and compresses the lowest pressure refrigerant flowing through the refrigerant circuit. The high stage compression unit 22 is a compression mechanism in the next stage (following stage) of the low stage compression unit 21. The high stage compression unit 22 is an uppermost (last stage) compression mechanism, and sucks and compresses the refrigerant compressed by the lower stage compression unit 21 in the previous stage. The refrigerant compressed by the high-stage compression unit 22 and discharged to the second discharge pipe 22b becomes the highest pressure refrigerant that flows through the refrigerant circuit.

  In the present embodiment, each of the compression units 21 and 22 is a displacement type compression mechanism such as a rotary type or a scroll type. The compressor drive motor is inverter-controlled by the control unit.

  Each of the first discharge pipe 21b and the second discharge pipe 22b is provided with an oil separator. The oil separator is a small container that separates lubricating oil contained in the refrigerant circulating in the refrigerant circuit. Although not shown in FIG. 1, an oil return pipe including a capillary tube extends from the lower part of each oil separator toward each of the suction pipes 21a and 22a, and the oil separated from the refrigerant is two-stage compressor. Return to 20.

(1-2) First and second switching mechanisms The first switching mechanism 31 and the second switching mechanism 32 switch the direction of the refrigerant flow in the refrigerant circuit to switch between the cooling operation cycle and the heating operation cycle. Each mechanism is a four-way switching valve.

  The first switching mechanism 31 is connected to the first discharge pipe 21 b, the second suction pipe 22 a, the gas side pipe of the first sub heat exchange unit 41, and the low pressure refrigerant pipe 19. The low-pressure refrigerant pipe 19 is a refrigerant pipe through which the low-pressure gas refrigerant in the outdoor unit 11 flows, and sends the refrigerant to the first suction pipe 21 a via the internal heat exchanger 62.

  The second switching mechanism 32 is connected to the second discharge pipe 22 b, the communication refrigerant pipe 14, the gas side pipe of the main heat exchange unit 44, and the low pressure refrigerant pipe 19.

  During the cooling operation, the switching mechanisms 31 and 32 cause the heat exchange units 41 and 44 to function as a cooler for the refrigerant compressed by the two-stage compressor 20 and pass through the expansion mechanism 70 and the indoor motor-operated valve 12b. The state shown in FIG. 1 is set so that the indoor heat exchanger 12a functions as an evaporator (heater) of the expanded refrigerant. Further, the switching mechanisms 31 and 32 cause the indoor heat exchanger 12a to function as a refrigerant cooler compressed by the two-stage compressor 20 during the heating operation, and the expansion mechanism 70 and the first outdoor motor operated valve 52. Or it will be in the state shown in FIG. 3 so that the outdoor heat exchanger 40 may function as an evaporator of the refrigerant | coolant expanded through the 1st capillary tube 51a.

  That is, the switching mechanisms 31 and 32 focus on only the two-stage compressor 20, the outdoor heat exchanger 40, the expansion mechanism 70, and the indoor heat exchanger 12a as components of the refrigerant circuit. The cooling operation cycle in which the refrigerant is circulated in the order of the compressor 40, the expansion mechanism 70, and the indoor heat exchanger 12a, and the refrigerant is circulated in the order of the two-stage compressor 20, the indoor heat exchanger 12a, the expansion mechanism 70, and the outdoor heat exchanger 40. It plays a role of switching between heating operation cycles.

(1-3) Outdoor Heat Exchanger The outdoor heat exchanger 40 includes the first sub heat exchange unit 41 and the main heat exchange unit 44 as described above. During the cooling operation, the first sub heat exchange unit 41 functions as an intercooler that cools the refrigerant being compressed, and the main heat exchange unit 44 functions as a gas cooler that cools the highest-pressure refrigerant. The main heat exchange unit 44 has a larger capacity than the first sub heat exchange unit 41. Moreover, at the time of heating operation, both the 1st sub heat exchange part 41 and the main heat exchange part 44 function as an evaporator (heater) of a refrigerant | coolant.

  The first sub heat exchange unit 41 and the main heat exchange unit 44 are arranged in parallel and integrated as one outdoor heat exchanger 40. Water or air is supplied to the outdoor heat exchanger 40 as a cooling source or a heating source for exchanging heat with the refrigerant flowing inside. Here, air (outside air) is supplied to the outdoor heat exchanger 40 from a blower fan (not shown).

  Further, an intercooler pipe 41a, which is a branch pipe, extends from the pipe on the check valve 51b side of the first sub heat exchanger 41 toward the second suction pipe 22a. As shown in FIGS. 1 and 3, the intercooler pipe 41 a is provided with an intercooler pipe check valve.

(1-4) First Outdoor Motorized Valve The first outdoor motorized valve 52 is disposed between the main heat exchange unit 44 and the bridge circuit 55. During the cooling operation, the first outdoor motor operated valve 52 is fully opened. During the heating operation, the opening degree of the first outdoor motor operated valve 52 is adjusted so that the refrigerant flow from the bridge circuit 55 to the main heat exchanging portion 44 does not drift, and also plays a role as an expansion mechanism.

(1-5) Capillary tube The first capillary tube 51 a is arranged between the first sub heat exchange unit 41 and the bridge circuit 55. In other words, the first capillary tube 51a is arranged on the refrigerant inflow side of the first sub heat exchange unit 41 during heating. The first capillary tube 51a decompresses the refrigerant sent from the indoor heat exchanger 12a to the first sub heat exchange unit 41 during heating. The first capillary tube 51a is a copper thin tube having an inner diameter of 0.6 mm to 2 mm. The inner diameter dimension and the length dimension of the first capillary tube 51a are determined by the size of the first sub heat exchanging section 41 and the main heat exchanging section 44 and the flow rate of the refrigerant flowing therethrough. That is, the first capillary tube 51a is adjusted in inner diameter and length so that the refrigerant flow from the bridge circuit 55 to the first sub heat exchanging portion 41 does not drift during heating operation, and also serves as an expansion mechanism. Fulfill. In other words, the first capillary tube 51a has an alternative function as an expansion mechanism of the first outdoor motor operated valve 52 described above.

(1-6) First Check Valve The first check valve 51 b is disposed between the first sub heat exchange unit 41 and the bridge circuit 55. In other words, the first check valve 51b is also arranged on the refrigerant inflow side of the first sub heat exchange unit 41 during heating. The above-described intercooler pipe 41a branches off from between the first sub heat exchange part 41 and the check valve 51b. The first check valve 51b stops the flow of the refrigerant from the first sub heat exchanger 41 to the indoor heat exchanger 12a during cooling. Further, the first check valve 51b allows the flow of the refrigerant from the indoor heat exchanger 12a to the first sub heat exchange unit 41 during heating.

(1-7) Bridge circuit The bridge circuit 55 is provided between the outdoor heat exchanger 40 and the indoor heat exchanger 12a. The bridge circuit 55 is connected to the inlet pipe 81 of the receiver 80 via the economizer heat exchanger 61, the internal heat exchanger 62 and the expansion mechanism 70, and the outlet pipe 82 of the receiver 80 via the supercooling heat exchanger 90. It is connected to the.

  The bridge circuit 55 has four check valves 55a, 55b, 55c, and 55d. The inlet check valve 55a is a check valve that allows only the flow of refrigerant from the outdoor heat exchanger 40 toward the inlet pipe 81 of the receiver 80. The inlet check valve 55b is a check valve that allows only a refrigerant flow from the indoor heat exchanger 12a to the inlet pipe 81 of the receiver 80. The outlet check valve 55 c is a check valve that allows only the flow of refrigerant from the outlet pipe 82 of the receiver 80 toward the outdoor heat exchanger 40. The outlet check valve 55d is a check valve that allows only the flow of refrigerant from the outlet pipe 82 of the receiver 80 toward the indoor heat exchanger 12a. In other words, the inlet check valves 55a and 55b function to cause the refrigerant to flow from one of the outdoor heat exchanger 40 and the indoor heat exchanger 12a to the inlet pipe 81 of the receiver 80, and the outlet check valves 55c and 55d The outlet pipe 82 serves to flow the refrigerant to the other of the outdoor heat exchanger 40 and the indoor heat exchanger 12a.

(1-8) Economizer Heat Exchanger The economizer heat exchanger 61 has a high-pressure refrigerant heading from the bridge circuit 55 to the expansion mechanism 70 and the receiver 80, and an intermediate pressure obtained by branching and expanding a part of the high-pressure refrigerant. Exchange heat with the refrigerant. A second outdoor motor-operated valve 61b is provided in a pipe (injection pipe 61a) branched from the main refrigerant pipe that flows the refrigerant from the bridge circuit 55 to the expansion mechanism 70. The refrigerant that has expanded through the second outdoor motor-operated valve 61b and evaporated in the economizer heat exchanger 61 passes through the injection pipe 61a extending toward the intercooler pipe 41a and is second than the check valve of the intercooler pipe 41a. The refrigerant that flows into the portion close to the suction pipe 22a and cools the refrigerant sucked from the second suction pipe 22a into the high-stage compression section 22 is cooled.

(1-9) Internal heat exchanger The internal heat exchanger 62 passes through the expansion mechanism 70 and the high-pressure refrigerant from the bridge circuit 55 toward the expansion mechanism 70 and the receiver 80, and passes through the indoor heat exchanger 12a or the outdoor heat exchange. Heat exchange is performed with the low-pressure gas refrigerant that evaporates in the vessel 40 and flows through the low-pressure refrigerant pipe 19. The high-pressure refrigerant that has exited the bridge circuit 55 first passes through the economizer heat exchanger 61, then passes through the internal heat exchanger 62, and travels toward the expansion mechanism 70 and the receiver 80.

(1-10) Expansion Mechanism The expansion mechanism 70 decompresses and expands the high-pressure refrigerant that has flowed from the bridge circuit 55, and causes the intermediate-pressure refrigerant in a gas-liquid two-phase state to flow to the receiver 80. That is, during the cooling operation, the expansion mechanism 70 depressurizes the refrigerant sent from the outdoor main heat exchanger 44 functioning as a high-pressure refrigerant gas cooler (radiator) to the indoor heat exchanger 12a functioning as a low-pressure refrigerant evaporator. To do. On the other hand, during the heating operation, the expansion mechanism 70 decompresses the refrigerant sent from the indoor heat exchanger 12a functioning as a high-pressure refrigerant gas cooler (radiator) to the outdoor heat exchanger 40 functioning as a low-pressure refrigerant evaporator. The expansion mechanism 70 includes an expander 71 and a third outdoor motor operated valve 72. The expander 71 plays a role of recovering the throttle loss in the decompression process of the refrigerant as effective work (energy).

(1-11) Receiver The receiver 80 separates the gas-liquid two-phase intermediate pressure refrigerant that has left the expansion mechanism 70 and enters the internal space from the inlet pipe 81 into liquid refrigerant and gas refrigerant. The separated gas refrigerant passes through the fourth outdoor motor-operated valve 91 provided in the low-pressure return pipe 91 a to become a low-pressure gas-rich refrigerant and is sent to the supercooling heat exchanger 90. The separated liquid refrigerant is sent to the supercooling heat exchanger 90 through the outlet pipe 82.

(1-12) Supercooling Heat Exchanger The supercooling heat exchanger 90 performs heat exchange between the low-pressure gas refrigerant and the intermediate-pressure liquid refrigerant output from the outlet pipe 82 of the receiver 80. Part of the intermediate-pressure liquid refrigerant that has exited from the outlet pipe 82 of the receiver 80 flows through the branch pipe 92a that branches from between the receiver 80 and the supercooling heat exchanger 90 during the cooling operation, and the fifth outdoor motor-operated valve 92. And becomes a low-pressure refrigerant in a gas-liquid two-phase state. The low-pressure refrigerant decompressed by the fifth outdoor motor-operated valve 92 during the cooling operation is merged with the low-pressure refrigerant decompressed by the fourth outdoor motor-operated valve 91, and a bridge circuit is connected from the outlet pipe 82 of the receiver 80 in the supercooling heat exchanger 90. The heat is exchanged with the intermediate-pressure liquid refrigerant heading 55, and flows from the supercooling heat exchanger 90 to the low-pressure refrigerant pipe 19 through the low-pressure return pipe 91 a while being superheated. On the other hand, the intermediate-pressure liquid refrigerant from the outlet pipe 82 of the receiver 80 toward the bridge circuit 55 is deprived of heat in the supercooling heat exchanger 90 and flows to the bridge circuit 55 with supercooling.

  During the heating operation, the fifth outdoor motor-operated valve 92 is closed, and the refrigerant does not flow into the branch pipe 92a. However, the intermediate-pressure liquid refrigerant from the outlet pipe 82 of the receiver 80 and the fourth outdoor motor-operated valve 91 reduce the pressure. The low-pressure refrigerant that has been subjected to heat exchange in the supercooling heat exchanger 90.

(1-13) Indoor Heat Exchanger The indoor heat exchanger 12a is provided in each of the plurality of indoor units 12, and functions as a refrigerant evaporator during a cooling operation and as a refrigerant cooler during a heating operation. Water and air are flown through these indoor heat exchangers 12a as cooling targets or heating targets that exchange heat with the refrigerant flowing in the interior. Here, indoor air from an indoor fan (not shown) flows into the indoor heat exchanger 12a, and cooled or heated conditioned air is supplied into the room.

  One end of the indoor heat exchanger 12a is connected to the indoor motor-operated valve 12b, and the other end of the indoor heat exchanger 12a is connected to the communication refrigerant pipe 14.

(1-14) Indoor electric valve The indoor electric valve 12b is provided in each of the plurality of indoor units 12, and adjusts the amount of refrigerant flowing to the indoor heat exchanger 12a, and performs decompression and expansion of the refrigerant. The indoor motor operated valve 12b is disposed between the communication refrigerant pipe 13 and the indoor heat exchanger 12a.

(1-15) Control Unit The control unit is connected to the compressor drive motor of the two-stage compressor 20, the first and second switching mechanisms 31, 32, and the respective motorized valves 12b, 52, 61b, 72, 91, 92. This is a microcomputer. This control unit performs rotation speed control of the compressor drive motor, switching between the cooling operation cycle and the heating operation cycle, adjustment of the electric valve opening degree, and the like based on information such as the indoor set temperature input from the outside.

(2) Operation of Air Conditioner The operation of the air conditioner 10 will be described with reference to FIGS. FIG. 2 is a pressure-enthalpy diagram (ph diagram) of the refrigeration cycle during cooling operation. FIG. 4 is a pressure-enthalpy diagram (ph diagram) of the refrigeration cycle during heating operation. In FIGS. 2 and 4, the curves indicated by the one-dot chain line that protrudes upward are the saturated liquid line and the dry saturated vapor line of the refrigerant. 2 and 4, the points with English letters on the refrigeration cycle represent the refrigerant pressure and enthalpy at the points represented by the same letters in FIGS. 1 and 3, respectively. For example, the refrigerant at point B in FIG. 1 is in the state of pressure and enthalpy at point B in FIG. Note that each operation control during the cooling operation and the heating operation of the air conditioner 10 is performed by the control unit.

(2-1) Operation at the time of cooling operation At the time of cooling operation, the refrigerant moves in the direction of the arrow along the refrigerant pipe shown in FIG. 1 into the two-stage compressor 20, the outdoor heat exchanger 40, the expansion mechanism 70, and the indoor heat. It circulates in the refrigerant circuit in the order of the exchanger 12a. Hereinafter, operation | movement of the air conditioning apparatus 10 at the time of air_conditionaing | cooling operation is demonstrated, referring FIG. 1 and FIG.

  The low-pressure gas refrigerant (point A) sucked into the two-stage compressor 20 from the first suction pipe 21a is compressed by the low-stage compression unit 21 and discharged to the first discharge pipe 21b (point B). The discharged refrigerant passes through the first switching mechanism 31 and is cooled by the first sub heat exchange unit 41 functioning as an intercooler, and then flows into the intercooler pipe 41a. The refrigerant flowing through the intercooler pipe 41a is heat-exchanged in the economizer heat exchanger 61 and merged with the intermediate pressure refrigerant (point L) flowing through the injection pipe 61a, and then flows into the second suction pipe 22a (point H). .

  The refrigerant sucked into the high stage compression unit 22 from the second suction pipe 22a is compressed and discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32, is cooled by the main heat exchanging portion 44 that functions as a gas cooler, and flows to the economizer heat exchanger 61 through the inlet check valve 55a of the bridge circuit 55. (Point J).

  The high-pressure refrigerant that has passed through the inlet check valve 55a of the bridge circuit 55 flows into the economizer heat exchanger 61, and a part thereof branches to flow to the second outdoor motor-operated valve 61b. The intermediate-pressure refrigerant (point K) that has been reduced in pressure and expanded by the second outdoor electric valve 61b into a gas-liquid two-phase state is converted into a high-pressure refrigerant (point K) from the bridge circuit 55 to the internal heat exchanger 62 in the economizer heat exchanger 61. It exchanges heat with the point J) and becomes an intermediate-pressure gas refrigerant (point L) and flows into the intercooler pipe 41a from the injection pipe 61a as described above.

  The high-pressure refrigerant (point M) that has exchanged heat with the intermediate-pressure refrigerant that has exited the second outdoor motor-operated valve 61 b and has exited the economizer heat exchanger 61 in a state where the temperature has further decreased, then flows through the internal heat exchanger 62. And flows to the expansion mechanism 70 (point N). In the internal heat exchanger 62, heat exchange is performed with the low-pressure refrigerant flowing from the low-pressure refrigerant pipe 19 described later to the first suction pipe 21 a of the two-stage compressor 20, and the high-pressure refrigerant in the state of point M drops in temperature. It becomes a high-pressure refrigerant in the N state.

  The high-pressure refrigerant (point N) exiting the internal heat exchanger 62 is branched into two and flows to the expander 71 of the expansion mechanism 70 and the third outdoor motor-operated valve 72 of the expansion mechanism 70, respectively. The intermediate pressure refrigerant (point P) decompressed / expanded by the expander 71 and the intermediate pressure refrigerant (point O) decompressed / expanded by the third outdoor motor-operated valve 72 are joined from the inlet pipe 81 to the internal space of the receiver 80. (Point Q). The gas-liquid two-phase intermediate pressure refrigerant flowing into the receiver 80 is separated into liquid refrigerant and gas refrigerant in the internal space of the receiver 80.

  The liquid refrigerant (point R) separated by the receiver 80 flows directly to the supercooling heat exchanger 90 through the outlet pipe 82, and the gas refrigerant (point U) separated by the receiver 80 is the fourth outdoor motor-operated valve. The pressure is reduced at 91 to form a low-pressure refrigerant (point W) and flow to the supercooling heat exchanger 90. The intermediate pressure refrigerant from the outlet pipe 82 of the receiver 80 toward the supercooling heat exchanger 90 is branched before the supercooling heat exchanger 90, and one of the refrigerants passes through the supercooling heat exchanger 90 toward the bridge circuit 55 and the other. Flows to the fifth outdoor motor operated valve 92 of the branch pipe 92a. The low-pressure refrigerant (point S) in the gas-liquid two-phase state that has been decompressed after passing through the fifth outdoor motor-operated valve 92 merges with the low-pressure refrigerant (point W) that has passed through the fourth outdoor motor-operated valve 91 (point X), It flows to the low-pressure refrigerant pipe 19 through the supercooling heat exchanger 90. The low-pressure refrigerant (point X) flowing toward the low-pressure refrigerant pipe 19 due to heat exchange in the supercooling heat exchanger 90 evaporates to become a superheated low-pressure refrigerant (point Y) and flows toward the bridge circuit 55. The intermediate-pressure refrigerant (point R) becomes an intermediate-pressure refrigerant (point T) that is deprived of heat and supercooled.

  The intermediate pressure refrigerant (point T) that has been supercooled by the supercooling heat exchanger 90 flows through the outlet check valve 55d of the bridge circuit 55 to the communication refrigerant pipe 13. The refrigerant that has entered the indoor unit 12 from the communication refrigerant pipe 13 expands when passing through the indoor motor-operated valve 12b, and flows into the indoor heat exchanger 12a as a gas-liquid two-phase low-pressure refrigerant (point V). This low-pressure refrigerant takes heat from the indoor air in the indoor heat exchanger 12a and becomes a superheated low-pressure gas refrigerant (point Z). The low-pressure refrigerant that has exited the indoor unit 12 flows to the low-pressure refrigerant pipe 19 via the communication refrigerant pipe 14 and the fourth switching mechanism 34.

  The low-pressure refrigerant (point Z) returned from the indoor unit 12 and the low-pressure refrigerant (point Y) flowing from the supercooling heat exchanger 90 merge at the low-pressure refrigerant pipe 19 (point AB), and the internal heat exchanger. The first suction pipe 21a returns to the two-stage compressor 20 through 62. As described above, in the internal heat exchanger 62, the low-pressure refrigerant (point AB) that goes to the two-stage compressor 20 and the high-pressure refrigerant (point M) that goes from the bridge circuit 55 to the receiver 80 perform heat exchange.

  As described above, the refrigerant circulates in the refrigerant circuit, so that the air conditioner 10 performs the cooling operation cycle.

(2-2) Operation at the time of heating operation During the heating operation, the refrigerant is in the direction of the arrow along the refrigerant pipe shown in FIG. It circulates in the refrigerant circuit in the order of the exchanger 40. Hereinafter, operation | movement of the air conditioning apparatus 10 at the time of heating operation is demonstrated, referring FIG. 3 and FIG.

  The low-pressure gas refrigerant (point A) sucked into the two-stage compressor 20 from the first suction pipe 21a is compressed by the low-stage compression unit 21 and discharged to the first discharge pipe 21b (point B). The discharged refrigerant passes through the first switching mechanism 31 and flows through the second suction pipe 22a. In addition, since the intermediate pressure refrigerant (point L) that is heat-exchanged in the economizer heat exchanger 61 and flows through the injection pipe 61a also flows into the second suction pipe 22a, the temperature of the refrigerant decreases (point H). .

  The refrigerant sucked into the high stage compression unit 22 from the second suction pipe 22a is compressed and discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32 and flows into the indoor unit 12 via the communication refrigerant pipe 14 (point Z).

  The high-pressure refrigerant that has entered the indoor unit 12 from the communication refrigerant pipe 14 radiates heat to the indoor air in the indoor heat exchanger 12a that functions as a refrigerant cooler, and warms the indoor air. The high-pressure refrigerant (point V) whose temperature has dropped due to heat exchange in the indoor heat exchanger 12a is slightly decompressed when passing through the indoor motor-operated valve 12b, passes through the communication refrigerant pipe 13, and the bridge circuit 55 of the outdoor unit 11 To the economizer heat exchanger 61 from the inlet check valve 55b (point J).

  The high-pressure refrigerant (point J) that has exited the bridge circuit 55 flows into the economizer heat exchanger 61, and a part of the high-pressure refrigerant branches to the second outdoor motor-operated valve 61b. The intermediate-pressure refrigerant (point K) that has been reduced in pressure and expanded by the second outdoor electric valve 61b into a gas-liquid two-phase state is converted into a high-pressure refrigerant (point K) from the bridge circuit 55 to the internal heat exchanger 62 in the economizer heat exchanger 61. It exchanges heat with the point J) and becomes an intermediate-pressure gas refrigerant (point L) and flows from the injection pipe 61a into the intercooler pipe 41a.

  The high-pressure refrigerant (point M) that has exchanged heat with the intermediate-pressure refrigerant that has exited the second outdoor motor-operated valve 61 b and has exited the economizer heat exchanger 61 in a state where the temperature has further decreased, then flows through the internal heat exchanger 62. And flows to the expansion mechanism 70 (point N). In the internal heat exchanger 62, heat exchange is performed with the low-pressure refrigerant flowing from the low-pressure refrigerant pipe 19 described later to the first suction pipe 21 a of the two-stage compressor 20, and the high-pressure refrigerant in the state of point M drops in temperature. It becomes a high-pressure refrigerant in the N state.

  The high-pressure refrigerant (point N) exiting the internal heat exchanger 62 is branched into two and flows to the expander 71 of the expansion mechanism 70 and the third outdoor motor-operated valve 72 of the expansion mechanism 70, respectively. The intermediate pressure refrigerant (point P) decompressed / expanded by the expander 71 and the intermediate pressure refrigerant (point O) decompressed / expanded by the third outdoor motor-operated valve 72 are joined from the inlet pipe 81 to the internal space of the receiver 80. (Point Q). The gas-liquid two-phase intermediate pressure refrigerant flowing into the receiver 80 is separated into liquid refrigerant and gas refrigerant in the internal space of the receiver 80.

  The liquid refrigerant (point R) separated by the receiver 80 flows directly to the supercooling heat exchanger 90 through the outlet pipe 82, and the gas refrigerant (point U) separated by the receiver 80 is the fourth outdoor motor-operated valve. The pressure is reduced at 91 to form a low-pressure refrigerant (point W) and flow to the supercooling heat exchanger 90. The intermediate pressure refrigerant from the outlet pipe 82 of the receiver 80 toward the supercooling heat exchanger 90 does not flow into the branch pipe 92a because the fifth outdoor motor-operated valve 92 is closed, and the entire amount flows into the supercooling heat exchanger 90. . In the subcooling heat exchanger 90, heat is generated between the intermediate pressure refrigerant (point R) flowing from the outlet pipe 82 of the receiver 80 and the low pressure refrigerant (points W and X) decompressed by the fourth outdoor motor-operated valve 91. Exchange is performed. By this heat exchange, the low-pressure refrigerant (point X) flowing toward the low-pressure refrigerant pipe 19 evaporates to become a superheated low-pressure refrigerant (point Y), and the intermediate-pressure refrigerant (point R) from the receiver 80 toward the bridge circuit 55. ) Becomes an intermediate pressure refrigerant (point T) which is deprived of heat and supercooled.

  The intermediate-pressure refrigerant that has exited the supercooling heat exchanger 90 and passed through the outlet check valve 55d of the bridge circuit 55 is divided into four paths, and is expanded and depressurized by the first outdoor motor-operated valve 52 and the first capillary tube 51a, respectively. It becomes a gas-liquid two-phase low-pressure refrigerant (point AC). At this time, the opening degree of the first outdoor motor operated valve 52 and the inner diameter dimension / length dimension of the first capillary tube 51a depend on the capacity and pressure loss amount of the main heat exchanging part 44 and the first sub heat exchanging part 41, respectively. Thus, the refrigerant is prevented from drifting to any one of the heat exchangers.

  The low-pressure refrigerant in each path that has flowed into the first sub heat exchange unit 41 and the main heat exchange unit 44 of the outdoor heat exchanger 40 takes heat from the outside air and evaporates to become a superheated low-pressure gas refrigerant. After passing through the first and second switching mechanisms 31, 32, they merge (point AD).

  The low-pressure refrigerant (point AD) merged on the downstream side of the first and second switching mechanisms 31 and 32 merges with the low-pressure refrigerant (point Y) flowing from the supercooling heat exchanger 90 in the low-pressure refrigerant pipe 19 ( Point AB) returns to the two-stage compressor 20 from the first suction pipe 21a through the internal heat exchanger 62. As described above, in the internal heat exchanger 62, the low-pressure refrigerant (point AB) that goes to the two-stage compressor 20 and the high-pressure refrigerant (point M) that goes from the bridge circuit 55 to the receiver 80 perform heat exchange.

  As described above, the refrigerant circulates in the refrigerant circuit, whereby the air conditioner 10 performs the heating operation cycle.

(3) Features of the air conditioner (3-1)
In the air conditioner 10 according to the present embodiment, the main heat exchange unit 44 is provided with the first outdoor electric valve 52 on the refrigerant inflow side during cooling, and the first sub heat exchange unit 41 is supplied with refrigerant during cooling. A first capillary tube 51a and a first check valve 51b are provided on the side. In the present embodiment, the expansion mechanism 70 and the first outdoor electric valve 52 function as a first expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating. On the other hand, the refrigerant sent from the indoor heat exchanger 12a to the sub heat exchanger 41 during heating is decompressed by the expansion mechanism 70 and the first capillary tube 51a. The check valve 51b stops the flow of the refrigerant from the first sub heat exchange unit 41 to the indoor heat exchanger 12a during cooling. Thereby, drift adjustment of a refrigerant | coolant can be performed, without providing an electrically operated valve with respect to the 1st sub heat exchange part 41 separately. As a result, it is possible to reduce the cost associated with the manufacture of the air conditioner 10.

  Moreover, when many motor operated valves are provided in the air conditioner 10, the control of the motor operated valves becomes complicated. The air conditioning apparatus 10 according to the present embodiment adjusts the flow direction of the refrigerant with respect to the first sub heat exchange unit 41 by the first check valve 51b, and adjusts the pressure of the refrigerant sent to the first sub heat exchange unit 41 to the first capillary. It adjusts with the tube 51a. Thereby, complication of control of a motor operated valve can be suppressed.

(4) Modification (4-1) Modification A
In the air conditioning apparatus 10 according to the above embodiment, the first capillary tube 51a and the first check valve 51b are arranged between the bridge circuit 55 and the first sub heat exchange unit 41. Here, it is also possible to configure the air conditioner 100 including the outdoor unit 111 instead of the outdoor unit 11. The outdoor unit 111 includes a bridge circuit 155 instead of the bridge circuit 55. The bridge circuit 155 does not include the outlet check valve 55 c among the four check valves included in the bridge circuit 55. As described above, the outlet check valve 55c is a check valve that allows only the flow of refrigerant from the outlet pipe 82 of the receiver 80 toward the outdoor heat exchanger 40. In the outdoor unit 111, as shown in FIGS. 5 and 6, a sixth outdoor motor-operated valve 50 and a first branch passage 50 a are arranged between the supercooling heat exchanger 90 and the outdoor heat exchanger 40. The sixth outdoor motor-operated valve 50 is fully opened during the cooling operation, and the opening degree is adjusted so that the refrigerant flow to the main heat exchange unit 44 does not drift during the heating operation. The first and second check valves 51b and 52b and the first and second capillary tubes 51a and 52a are disposed between the first branch path 50a and the heat exchange units 41 and 44, respectively. The second check valve 52b stops the flow of the refrigerant from the main heat exchange unit 44 to the first branch passage 50a during cooling. The second capillary tube 52a has the same configuration and function as the first capillary tube 51a. The branch pipe 144a is a pipe branched from a pipe extending from the main heat exchange unit 44 to the second check valve 52b. The branch pipe 144a allows the refrigerant to flow from the main heat exchange unit 44 to the bridge circuit 155 during cooling.

  Specifically, at the time of cooling, as shown in FIG. 5, the refrigerant compressed by the high-stage compression unit 22 is discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32, is cooled by the main heat exchanging unit 44 that functions as a gas cooler, reaches the bridge circuit 155 through the branch pipe 144 a, and checks the inlet of the bridge circuit 155. It flows to the economizer heat exchanger 61 through the valve 55a (point J). Further, during heating, as shown in FIG. 6, the intermediate-pressure refrigerant that has exited the supercooling heat exchanger 90 passes through the sixth outdoor motor-operated valve 50 and reaches the first branch 50a. The opening degree of the sixth outdoor motor-operated valve 50 is adjusted so that the flow of the intermediate pressure refrigerant does not drift. The first branch path 50a branches the refrigerant whose flow is adjusted by the sixth outdoor motor-operated valve 50 to the heat exchange units 41 and 44.

  In the air conditioner 100 according to Modification A, the expansion mechanism 70 and the sixth outdoor motor-operated valve 50 function as a first expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating. . The refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating is also decompressed by the second capillary tube 52a. The sixth outdoor motor operated valve 50 also functions as a second expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the sub heat exchange unit 41 during heating. The refrigerant sent from the indoor heat exchanger 12a to the sub heat exchanger 41 during heating is also decompressed by the expansion mechanism 70 and the first capillary tube 51a. The check valves 51b and 52b stop the flow of the refrigerant from the heat exchange units 41 and 44 to the first branch passage 50a during cooling. The refrigerant that has passed through the main heat exchange unit 44 flows to the indoor heat exchanger 12a via the branch pipe 144a and the bridge circuit 155.

  By making the configuration of the outdoor unit as described above, the drift adjustment can be effectively performed without increasing the number of motor-operated valves used in the outdoor unit 111.

(4-2) Modification B
In the above-described embodiment, a two-stage compressor 20 having a single-shaft two-stage compression structure in which two compression units 21 and 22 are connected to a single drive shaft as a multi-stage compression mechanism of a refrigeration apparatus as a premise of the present invention. Is adopted. Here, it is also possible to employ a four-stage compressor 120 having a uniaxial four-stage compression structure.

  For example, as shown in FIG. 7, the air-conditioning apparatus 110 can be configured using a multistage compression mechanism 120 including four compression units 21 to 24. In the air conditioner 110, an outdoor unit 211 is connected to the indoor unit 12 instead of the outdoor unit 11 of the above embodiment. Here, the difference between the outdoor unit 11 and the outdoor unit 211 is mainly that the former employs the two-stage compressor 20 while the latter employs the four-stage compressor 120, and the former The outdoor heat exchanger 40 composed of two heat exchange units is employed, whereas the latter employs an outdoor heat exchanger 140 composed of four heat exchange units. In addition to the adoption of the four-stage compressor 120 and the outdoor heat exchanger 140, the third and fourth suction pipes 23a and 24a are used in addition to the first and second suction pipes 21a and 22a. In addition to the first and second discharge pipes 21b and 22b, the third and fourth discharge pipes 23b and 24b are used. Further, in addition to the first and second switching mechanisms 31 and 32, the third and fourth switching mechanisms 33 and 34 are used. In addition to the first capillary tube 51a, third and fourth check valves 53b and 54b are used in addition to the third and fourth capillary tubes 53a and 54a and the first check valve 51b, respectively. Specifically, it is as follows. In the following, different parts from the above embodiment will be described.

(4-2-1) Four-stage compressor The four-stage compressor 120 includes a first compressor in addition to the low-stage compression section 21, the high-stage compression section 22, and the compressor drive motor (not shown). This is a hermetic compressor in which the middle stage compression unit 23 and the second middle stage compression unit 24 are accommodated. A compressor drive motor drives the four compression parts 21-24 via a drive shaft. That is, the four-stage compressor 120 has a single-shaft four-stage compression structure in which four compression units 21 to 24 are connected to a single drive shaft. In the four-stage compressor 120, the low-stage compressor 21, the first middle-stage compressor 23, the second middle-stage compressor 24, and the high-stage compressor 22 are connected in series in this order. The low-stage compression unit 21 sucks the refrigerant from the first suction pipe 21a and discharges the refrigerant to the first discharge pipe 21b. The first middle-stage compression unit 23 sucks the refrigerant from the third suction pipe 23a and discharges the refrigerant to the third discharge pipe 23b. The second middle stage compressor 24 sucks the refrigerant from the fourth suction pipe 24a and discharges the refrigerant to the fourth discharge pipe 24b. The high-stage compression unit 22 sucks the refrigerant from the second suction pipe 22a and discharges the refrigerant to the second discharge pipe 22b.

  The low-stage compression unit 21 is a compression mechanism at the lowest stage (frontmost stage), and compresses the lowest pressure refrigerant flowing through the refrigerant circuit. The first middle stage compression unit 23 is a compression mechanism in the next stage (the rear stage side) of the low stage compression unit 21. That is, the first middle-stage compression unit 23 is a compression mechanism that is higher than the low-stage compression unit 21. The first middle stage compression unit 23 sucks and compresses the refrigerant compressed by the low stage compression unit 21. The second middle stage compression unit 24 is a compression mechanism in the next stage (rear stage side) of the first middle stage compression unit 23. That is, the second middle stage compression unit 24 is a compression mechanism that is higher than the first middle stage compression unit 23. The second middle stage compression unit 24 sucks and compresses the refrigerant compressed by the first middle stage compression unit 23. The high stage compression unit 22 is a compression mechanism in the next stage (the rear stage side) of the second middle stage compression unit 24. The high-stage compression unit 22 is an uppermost (last stage) compression mechanism, and sucks and compresses the refrigerant compressed by the second middle-stage compression unit 24. The refrigerant compressed by the high-stage compression unit 22 and discharged to the second discharge pipe 22b becomes the highest pressure refrigerant that flows through the refrigerant circuit. Each compression part 21-24 is a volume type compression mechanism, such as a rotary type and a scroll type. The compressor drive motor is inverter-controlled by the control unit.

  Each of the first discharge pipe 21b, the second discharge pipe 22b, the third discharge pipe 23b, and the fourth discharge pipe 24b is provided with an oil separator. Although not shown, an oil return pipe including a capillary tube extends from the lower part of each oil separator toward each of the suction pipes 21a to 24a, and the oil separated from the refrigerant is supplied to the four-stage compressor 120. return.

(4-2-2) First to Fourth Switching Mechanisms The first to fourth switching mechanisms 31 to 34 switch the cooling operation cycle and the heating operation cycle by switching the direction of the refrigerant flow in the refrigerant circuit. Are four-way switching valves.

  The first switching mechanism 31 is connected to the first discharge pipe 21 b, the second suction pipe 22 a, the gas side pipe of the first sub heat exchange unit 41, and the low pressure refrigerant pipe 19. The low-pressure refrigerant pipe 19 is a refrigerant pipe through which the low-pressure gas refrigerant in the outdoor unit 211 flows, and sends the refrigerant to the first suction pipe 21 a via the internal heat exchanger 62.

  The second switching mechanism 32 is connected to the second discharge pipe 22 b, the communication refrigerant pipe 14, the gas side pipe of the main heat exchange unit 44, and the low pressure refrigerant pipe 19.

  The third switching mechanism 33 is connected to the third discharge pipe 23 b, the fourth suction pipe 24 a, the gas side pipe of the second sub heat exchange unit 42, and the low pressure refrigerant pipe 19.

  The fourth switching mechanism 34 is connected to the fourth discharge pipe 24 b, the second suction pipe 22 a, the gas side pipe of the third sub heat exchange unit 43, and the low pressure refrigerant pipe 19.

  The switching mechanisms 31 to 34 function the sub heat exchange units 41 to 43 and the main heat exchange unit 44 as coolers for the refrigerant compressed by the four-stage compressor 120 during the cooling operation, and the expansion mechanism 70 and the indoor unit The state shown in FIG. 7 is set so that the indoor heat exchanger 12a functions as an evaporator (heater) of the refrigerant that has expanded through the motor-operated valve 12b. Further, the switching mechanisms 31 to 34 function the indoor heat exchanger 12a as a refrigerant cooler compressed by the four-stage compressor 120 during the heating operation, and the expansion mechanism 70 and the first outdoor motor operated valve 52. Or it will be in the state shown in FIG. 9 so that the outdoor heat exchanger 40 may function as an evaporator of the refrigerant | coolant which expanded through the 1st capillary tube 51a.

  That is, the switching mechanisms 31 to 34 focus on only the four-stage compressor 120, the outdoor heat exchanger 140, the expansion mechanism 70, and the indoor heat exchanger 12a as components of the refrigerant circuit. The cooling operation cycle in which the refrigerant is circulated in the order of the condenser 140, the expansion mechanism 70, and the indoor heat exchanger 12a, and the refrigerant is circulated in the order of the four-stage compressor 120, the indoor heat exchanger 12a, the expansion mechanism 70, and the outdoor heat exchanger 140. It plays a role of switching between heating operation cycles.

(4-2-3) Outdoor Heat Exchanger As described above, the outdoor heat exchanger 140 includes the first sub heat exchange unit 41, the second sub heat exchange unit 42, the third sub heat exchange unit 43, and the main heat exchange. Part 44. During the cooling operation, the first to third sub heat exchange units 41 to 43 function as an intercooler that cools the refrigerant being compressed, and the main heat exchange unit 44 functions as a gas cooler that cools the highest-pressure refrigerant. The main heat exchange unit 44 has a larger capacity than the first to third sub heat exchange units 41 to 43. Further, during the heating operation, all of the first to third sub heat exchange units 41 to 43 and the main heat exchange unit 44 function as a refrigerant evaporator (heater).

  The first to third sub heat exchange units 41 to 43 and the main heat exchange unit 44 are arranged in parallel and integrated as one outdoor heat exchanger 140. Water or air is supplied to the outdoor heat exchanger 140 as a cooling source or a heat source for exchanging heat with the refrigerant flowing inside. Here, air (outside air) is supplied to the outdoor heat exchanger 140 from a blower fan (not shown).

  A first intercooler pipe 141a, which is a branch pipe, extends from the pipe on the check valve 51b side of the first sub heat exchange section 41 toward the third suction pipe 23a. A second intercooler pipe 142a, which is a branch pipe, extends from the pipe on the check valve 52b side of the second sub heat exchange section 42 toward the fourth suction pipe 24a. A third intercooler pipe 143a, which is a branch pipe, extends from the pipe on the check valve 53b side of the third sub heat exchange section 43 toward the second suction pipe 22a. As shown in FIGS. 7 and 9, the first intercooler pipe 141a, the second intercooler pipe 142a, and the third intercooler pipe 143a are each provided with a check valve for an intercooler pipe.

(4-2-4) First, Third, and Fourth Capillary Tubes The first capillary tube 51a is disposed between the first sub heat exchange unit 41 and the bridge circuit 55. The third capillary tube 53 a is disposed between the second sub heat exchange unit 42 and the bridge circuit 55. The fourth capillary tube 54 a is disposed between the third sub heat exchange unit 43 and the bridge circuit 55. Since the configurations and functions of the first, third, and fourth capillary tubes 51a, 53a, and 54a are the same as those in the above embodiment, the description thereof is omitted.

(4-2-5) First, Third, and Fourth Check Valves The first check valve 51b is disposed between the first sub heat exchange unit 41 and the bridge circuit 55. The third check valve 53 b is disposed between the second sub heat exchange unit 42 and the bridge circuit 55. The fourth check valve 54 b is disposed between the third sub heat exchange unit 43 and the bridge circuit 55. Since the functions of the first, third, and fourth check valves are also the same as those in the above embodiment, description thereof is omitted.

(4-2-6) Bridge circuit The bridge circuit 55 is provided between the outdoor heat exchanger 140 and the indoor heat exchanger 12a. The inlet check valve 55a is a check valve that allows only the flow of refrigerant from the outdoor heat exchanger 140 toward the inlet pipe 81 of the receiver 80. The outlet check valve 55 c is a check valve that allows only the flow of refrigerant from the outlet pipe 82 of the receiver 80 toward the outdoor heat exchanger 140. Since other configurations are the same as those of the above-described embodiment, description thereof is omitted.

(4-2-7) Economizer Heat Exchanger The function of the economizer heat exchanger 61 is the same as that in the above embodiment. However, the refrigerant that has expanded through the second outdoor motor-operated valve 61b and evaporated in the economizer heat exchanger 61 passes through the injection pipe 61a extending toward the second intercooler pipe 142a, and thereby the check valve of the intercooler pipe 142a. Rather, it flows into a portion closer to the fourth suction pipe 24a and cools the refrigerant sucked from the fourth suction pipe 24a into the second middle compression section 24.

(4-2-8) Control Unit The control unit includes a compressor drive motor for the four-stage compressor 120, first to fourth switching mechanisms 31 to 34, and motor-operated valves 12b, 52, 61b, 72, 91, and 92. It is a connected microcomputer. This control unit performs rotation speed control of the compressor drive motor, switching between the cooling operation cycle and the heating operation cycle, adjustment of the electric valve opening degree, and the like based on information such as the indoor set temperature input from the outside.

(4-2-9) Operation of Air Conditioner The operation of the air conditioner 110 will be described with reference to FIGS. FIG. 8 is a pressure-enthalpy diagram (ph diagram) of the refrigeration cycle during cooling operation. FIG. 10 is a pressure-enthalpy diagram (ph diagram) of the refrigeration cycle during heating operation. In FIGS. 8 and 10, the curves indicated by the one-dot chain line that protrudes upward are the saturated liquid line and the dry saturated vapor line of the refrigerant. 8 and 10, the points marked with English letters on the refrigeration cycle also represent the refrigerant pressure and enthalpy at the points represented by the same letters in FIGS. 7 and 9, respectively. Each operation control during the cooling operation and the heating operation of the air conditioner 110 is performed by the control unit.

(4-2-9-1) Operation During Cooling Operation During the cooling operation, the refrigerant is moved in the direction of the arrow along the refrigerant pipe shown in FIG. 7 into the four-stage compressor 120, the outdoor heat exchanger 140, and the expansion mechanism. 70 and the indoor heat exchanger 12a are circulated in the refrigerant circuit in this order. Hereinafter, the operation of the air conditioner 110 during the cooling operation will be described with reference to FIGS. 7 and 8.

  The low-pressure gas refrigerant (point A) sucked into the four-stage compressor 120 from the first suction pipe 21a is compressed by the low-stage compression section 21 and discharged to the first discharge pipe 21b (point B). The discharged refrigerant passes through the first switching mechanism 31 and is cooled by the first sub heat exchanger 41 functioning as an intercooler, and then flows into the third suction pipe 23a via the first intercooler pipe 141a ( Point C).

  The refrigerant sucked into the first middle compression section 23 from the third suction pipe 23a is compressed and discharged to the third discharge pipe 23b (point D). The discharged refrigerant passes through the third switching mechanism 33 and is cooled by the second sub heat exchanging section 42 functioning as an intercooler, and then flows to the second intercooler pipe 142a (point E). The refrigerant flowing through the second intercooler pipe 142a is heat-exchanged in the economizer heat exchanger 61 and merged with the intermediate-pressure refrigerant (point L) flowing through the injection pipe 61a, and then flows into the fourth suction pipe 24a (point). F).

  The refrigerant sucked into the second middle compression section 24 from the fourth suction pipe 24a is compressed and discharged to the fourth discharge pipe 24b (point G). The discharged refrigerant passes through the fourth switching mechanism 34 and is cooled by the third sub heat exchange unit 43 functioning as an intercooler, and then flows into the second suction pipe 22a via the third intercooler pipe 143a ( Point H).

  The refrigerant sucked into the high stage compression unit 22 from the second suction pipe 22a is compressed and discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32, is cooled by the main heat exchanging portion 44 that functions as a gas cooler, and flows to the economizer heat exchanger 61 through the inlet check valve 55a of the bridge circuit 55. (Point J).

  The high-pressure refrigerant that has passed through the inlet check valve 55a of the bridge circuit 55 flows into the economizer heat exchanger 61, and a part thereof branches to flow to the second outdoor motor-operated valve 61b. The intermediate-pressure refrigerant (point K) that has been reduced in pressure and expanded by the second outdoor electric valve 61b into a gas-liquid two-phase state is converted into a high-pressure refrigerant (point K) from the bridge circuit 55 to the internal heat exchanger 62 in the economizer heat exchanger 61. It exchanges heat with the point J), becomes an intermediate-pressure gas refrigerant (point L), and flows into the second intercooler pipe 142a from the injection pipe 61a as described above.

  The high-pressure refrigerant (point M) that has exchanged heat with the intermediate-pressure refrigerant that has exited the second outdoor motor-operated valve 61 b and has exited the economizer heat exchanger 61 in a state where the temperature has further decreased, then flows through the internal heat exchanger 62. And flows to the expansion mechanism 70 (point N). In the internal heat exchanger 62, heat exchange is performed with the low-pressure refrigerant flowing from the low-pressure refrigerant pipe 19 described later to the first suction pipe 21a of the four-stage compressor 120, and the temperature of the high-pressure refrigerant in the state of point M decreases. It becomes a high-pressure refrigerant in the N state.

  The high-pressure refrigerant (point N) exiting the internal heat exchanger 62 is branched into two and flows to the expander 71 of the expansion mechanism 70 and the third outdoor motor-operated valve 72 of the expansion mechanism 70, respectively. The intermediate pressure refrigerant (point P) decompressed / expanded by the expander 71 and the intermediate pressure refrigerant (point O) decompressed / expanded by the third outdoor motor-operated valve 72 are joined from the inlet pipe 81 to the internal space of the receiver 80. (Point Q). The gas-liquid two-phase intermediate pressure refrigerant flowing into the receiver 80 is separated into liquid refrigerant and gas refrigerant in the internal space of the receiver 80.

  The liquid refrigerant (point R) separated by the receiver 80 flows directly to the supercooling heat exchanger 90 through the outlet pipe 82, and the gas refrigerant (point U) separated by the receiver 80 is the fourth outdoor motor-operated valve. The pressure is reduced at 91 to form a low-pressure refrigerant (point W) and flow to the supercooling heat exchanger 90. The intermediate pressure refrigerant from the outlet pipe 82 of the receiver 80 toward the supercooling heat exchanger 90 is branched before the supercooling heat exchanger 90, and one of the refrigerants passes through the supercooling heat exchanger 90 toward the bridge circuit 55 and the other. Flows to the fifth outdoor motor operated valve 92 of the branch pipe 92a. The low-pressure refrigerant (point S) in the gas-liquid two-phase state that has been decompressed after passing through the fifth outdoor motor-operated valve 92 merges with the low-pressure refrigerant (point W) that has passed through the fourth outdoor motor-operated valve 91 (point X), It flows to the low-pressure refrigerant pipe 19 through the supercooling heat exchanger 90. The low-pressure refrigerant (point X) flowing toward the low-pressure refrigerant pipe 19 due to heat exchange in the supercooling heat exchanger 90 evaporates to become a superheated low-pressure refrigerant (point Y) and flows toward the bridge circuit 55. The intermediate-pressure refrigerant (point R) becomes an intermediate-pressure refrigerant (point T) that is deprived of heat and supercooled.

  The intermediate pressure refrigerant (point T) that has been supercooled by the supercooling heat exchanger 90 flows through the outlet check valve 55d of the bridge circuit 55 to the communication refrigerant pipe 13. The refrigerant that has entered the indoor unit 12 from the communication refrigerant pipe 13 expands when passing through the indoor motor-operated valve 12b, and flows into the indoor heat exchanger 12a as a gas-liquid two-phase low-pressure refrigerant (point V). This low-pressure refrigerant takes heat from the indoor air in the indoor heat exchanger 12a and becomes a superheated low-pressure gas refrigerant (point Z). The low-pressure refrigerant exiting the indoor unit 12 flows to the low-pressure refrigerant pipe 19 via the communication refrigerant pipe 14 and the second switching mechanism 32.

  The low-pressure refrigerant (point Z) returned from the indoor unit 12 and the low-pressure refrigerant (point Y) flowing from the supercooling heat exchanger 90 merge at the low-pressure refrigerant pipe 19 (point AB), and the internal heat exchanger. Through 62, the first suction pipe 21a returns to the four-stage compressor 120. As described above, in the internal heat exchanger 62, the low-pressure refrigerant (point AB) that goes to the four-stage compressor 120 and the high-pressure refrigerant (point M) that goes from the bridge circuit 55 to the receiver 80 perform heat exchange.

  As described above, the refrigerant circulates in the refrigerant circuit, so that the air conditioner 110 performs the cooling operation cycle.

(4-2-9-2) Operation at the time of heating operation During the heating operation, the refrigerant is in the direction of the arrow along the refrigerant pipe shown in FIG. 9, and the refrigerant is the four-stage compressor 120, the indoor heat exchanger 12a, and the expansion mechanism. 70 and the outdoor heat exchanger 140 are circulated in the refrigerant circuit in this order. Hereinafter, operation | movement of the air conditioning apparatus 110 at the time of heating operation is demonstrated, referring FIG. 9 and FIG.

  The low-pressure gas refrigerant (point A) sucked into the four-stage compressor 120 from the first suction pipe 21a is compressed by the low-stage compression unit 21 and discharged to the first discharge pipe 21b (point B). The discharged refrigerant passes through the first switching mechanism 31 and flows through the third suction pipe 23a (point C).

  The refrigerant sucked into the first middle compression section 23 from the third suction pipe 23a is compressed and discharged to the third discharge pipe 23b (point D). The discharged refrigerant passes through the third switching mechanism 33 and flows through the fourth suction pipe 24a. In addition, since the refrigerant | coolant (point L) of the intermediate pressure which heat-exchanges in the economizer heat exchanger 61 and flows through the injection piping 61a also flows into the 4th suction pipe 24a, the temperature of a refrigerant | coolant falls (point F). .

  The refrigerant sucked into the second middle compression section 24 from the fourth suction pipe 24a is compressed and discharged to the fourth discharge pipe 24b (point G). The discharged refrigerant passes through the fourth switching mechanism 34 and flows through the second suction pipe 22a (point H).

  The refrigerant sucked into the high stage compression unit 22 from the second suction pipe 22a is compressed and discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32 and flows into the indoor unit 12 via the communication refrigerant pipe 14 (point Z).

  The high-pressure refrigerant that has entered the indoor unit 12 from the communication refrigerant pipe 14 radiates heat to the indoor air in the indoor heat exchanger 12a that functions as a refrigerant cooler, and warms the indoor air. The high-pressure refrigerant (point V) whose temperature has dropped due to heat exchange in the indoor heat exchanger 12a is slightly decompressed when passing through the indoor motor-operated valve 12b, passes through the communication refrigerant pipe 13, and the bridge circuit 55 of the outdoor unit 11 To the economizer heat exchanger 61 from the inlet check valve 55b (point J).

  The high-pressure refrigerant (point J) that has exited the bridge circuit 55 flows into the economizer heat exchanger 61, and a part of the high-pressure refrigerant branches to the second outdoor motor-operated valve 61b. The intermediate-pressure refrigerant (point K) that has been reduced in pressure and expanded by the second outdoor electric valve 61b into a gas-liquid two-phase state is converted into a high-pressure refrigerant (point K) from the bridge circuit 55 to the internal heat exchanger 62 in the economizer heat exchanger 61. It exchanges heat with the point J) and becomes an intermediate-pressure gas refrigerant (point L) and flows from the injection pipe 61a into the second intercooler pipe 142a.

  The high-pressure refrigerant (point M) that has exchanged heat with the intermediate-pressure refrigerant that has exited the second outdoor motor-operated valve 61 b and has exited the economizer heat exchanger 61 in a state where the temperature has further decreased, then flows through the internal heat exchanger 62. And flows to the expansion mechanism 70 (point N). In the internal heat exchanger 62, heat exchange is performed with the low-pressure refrigerant flowing from the low-pressure refrigerant pipe 19 described later to the first suction pipe 21 a of the two-stage compressor 20, and the high-pressure refrigerant in the state of point M drops in temperature. It becomes a high-pressure refrigerant in the N state.

  The high-pressure refrigerant (point N) exiting the internal heat exchanger 62 is branched into two and flows to the expander 71 of the expansion mechanism 70 and the third outdoor motor-operated valve 72 of the expansion mechanism 70, respectively. The intermediate pressure refrigerant (point P) decompressed / expanded by the expander 71 and the intermediate pressure refrigerant (point O) decompressed / expanded by the third outdoor motor-operated valve 72 are joined from the inlet pipe 81 to the internal space of the receiver 80. (Point Q). The gas-liquid two-phase intermediate pressure refrigerant flowing into the receiver 80 is separated into liquid refrigerant and gas refrigerant in the internal space of the receiver 80.

  The liquid refrigerant (point R) separated by the receiver 80 flows directly to the supercooling heat exchanger 90 through the outlet pipe 82, and the gas refrigerant (point U) separated by the receiver 80 is the fourth outdoor motor-operated valve. The pressure is reduced at 91 to form a low-pressure refrigerant (point W) and flow to the supercooling heat exchanger 90. The intermediate pressure refrigerant from the outlet pipe 82 of the receiver 80 toward the supercooling heat exchanger 90 does not flow into the branch pipe 92a because the fifth outdoor motor-operated valve 92 is closed, and the entire amount flows into the supercooling heat exchanger 90. . In the subcooling heat exchanger 90, heat is generated between the intermediate pressure refrigerant (point R) flowing from the outlet pipe 82 of the receiver 80 and the low pressure refrigerant (points W and X) decompressed by the fourth outdoor motor-operated valve 91. Exchange is performed. By this heat exchange, the low-pressure refrigerant (point X) flowing toward the low-pressure refrigerant pipe 19 evaporates to become a superheated low-pressure refrigerant (point Y), and the intermediate-pressure refrigerant (point R) from the receiver 80 toward the bridge circuit 55. ) Becomes an intermediate pressure refrigerant (point T) which is deprived of heat and supercooled.

  The intermediate pressure refrigerant that has exited the supercooling heat exchanger 90 and passed through the outlet check valve 55d of the bridge circuit 55 is divided into four passages, and the first outdoor motor-operated valve 52 and the first, third, and fourth capillary tubes 51a. , 53a, and 54a are expanded and depressurized to become gas-liquid two-phase low-pressure refrigerant (point AC). At this time, the opening degree of the first outdoor motor operated valve 52 and the inner and outer dimensions of the first, third and fourth capillary tubes 51a, 53a and 54a are the main heat exchanging part 44 and the first to third sub heats. It is adjusted according to each capacity | capacitance and the amount of pressure loss of the exchange parts 41-43, and it is suppressed that a refrigerant | coolant drifts to either heat exchanger.

  The low-pressure refrigerant in each passage that has flowed into the first sub heat exchange unit 41, the second sub heat exchange unit 42, the third sub heat exchange unit 43, and the main heat exchange unit 44 of the outdoor heat exchanger 140 generates heat from the outside air. The gas is taken and evaporated to become a superheated low-pressure gas refrigerant that passes through the first to fourth switching mechanisms 31 to 34, and then merges (point AD).

  The low-pressure refrigerant (point AD) merged at the downstream side of the first to fourth switching mechanisms 31 to 34 merges with the low-pressure refrigerant (point Y) flowing from the supercooling heat exchanger 90 in the low-pressure refrigerant pipe 19 ( Point AB) returns to the four-stage compressor 120 from the first suction pipe 21a through the internal heat exchanger 62. As described above, in the internal heat exchanger 62, the low-pressure refrigerant (point AB) that goes to the four-stage compressor 120 and the high-pressure refrigerant (point M) that goes from the bridge circuit 55 to the receiver 80 perform heat exchange.

  As described above, the refrigerant circulates in the refrigerant circuit, so that the air conditioner 110 performs the heating operation cycle.

(4-2-10) Features of the Air Conditioner In the air conditioner 110 according to the modified example B, the number of compression units and sub heat exchange units is increased as compared with the air conditioner 10 according to the embodiment. When motor-operated valves are attached according to the number of sub heat exchange units, the manufacturing cost of the air conditioner further increases. In addition, the control of the motor-operated valve is further complicated.

  However, the air conditioning apparatus 110 according to the modified example B also includes the third and fourth check valves 53b and 54b and the third and fourth capillary tubes 53a for the second and third sub heat exchange units 42 and 43. , 54a, respectively. The expansion mechanism 70 and the first outdoor motor operated valve 52 function as a first expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating. The expansion mechanism 70 and the first, third, and fourth capillary tubes 51a, 53a, 54a decompress the refrigerant sent from the indoor heat exchanger 12a to the sub heat exchange unit 41 during heating. The check valves 51b, 53b, and 54b stop the flow of refrigerant from the sub heat exchange units 41 to 43 to the indoor heat exchanger 12a during cooling. Thereby, while being able to hold down the manufacturing cost of an air conditioning apparatus, the complexity of control of a motor operated valve can be suppressed.

(4-3) Modification C
In the air conditioner 110 according to the modified example B, the first, third, and fourth capillary tubes 51a, 53a, 54a and the first, third, and fourth check valves 51b, 53b, 54b are connected to the bridge circuit 55. And the sub heat exchange units 41 to 43. Here, instead of the outdoor unit 211, an air conditioner 300 including the outdoor unit 311 may be configured. As shown in FIGS. 11 and 12, the outdoor unit 311 further includes a sixth outdoor motor-operated valve 50 and a first branch 50 a between the bridge circuit 55 and the sub heat exchange units 41 to 43. At the time of heating, as shown in FIG. 12, the intermediate pressure refrigerant that has passed through the outlet check valve 55d of the bridge circuit 55 is a pipe provided with the first outdoor motor-operated valve 52 and a pipe provided with the sixth outdoor motor-operated valve. Divide into two roads. The opening degree of the first outdoor motor-operated valve 52 and the sixth outdoor motor-operated valve 50 is adjusted so that the flow of refrigerant sent from the bridge circuit 55 to the heat exchange units 41 to 44 does not drift. The first branch passage 50a causes the sub-heat exchangers 41 to 43 to branch the refrigerant whose flow is adjusted by the sixth outdoor motor-operated valve 50.

  In the air conditioner 300 according to the modified example C, the expansion mechanism 70 and the first outdoor motor-operated valve 52 function as a first expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating. . In addition, the sixth outdoor motor operated valve 50 functions as a second expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the sub heat exchange unit 41 during heating. The refrigerant sent from the indoor heat exchanger 12a to the sub heat exchanger 41 during heating is also decompressed by the expansion mechanism 70 and the first, third, and fourth capillary tubes 51a, 53a, 54a. The check valves 51b, 53b, and 54b stop the flow of refrigerant from the sub heat exchange units 41 to 43 to the indoor heat exchanger 12a during cooling.

  Also by doing in this way, manufacturing cost can be suppressed compared with the case where a motor-operated valve is provided with respect to all the sub heat exchange parts 41-43. Further, the flow adjustment can be performed more effectively by flowing the refrigerant adjusted by the sixth outdoor motor operated valve 50 through the first, third, and fourth capillary tubes 51a, 53a, 54a.

(4-4) Modification D
In Modification A, the outdoor unit 111 including the two-stage compressor 20 includes a bridge circuit 155 and a branch pipe 144a instead of the bridge circuit 55. Further, the outdoor unit 111 includes a second capillary tube 52 a and a second check valve 52 b instead of the first outdoor motor operated valve 52 with respect to the main heat exchanging unit 44. The air conditioner including the four-stage compressor 120 also includes the bridge circuit 155 and the branch pipe 144a used in the modified example A, and the second capillary tube is used instead of the first outdoor motor-operated valve 52 with respect to the main heat exchange unit 44. It is good also as a structure provided with 52a and the 2nd non-return valve 52b.

  13 and 14, the bridge circuit 55 in the outdoor unit 211 according to the modified example B is changed to a bridge circuit 155 and a branch pipe 144a, and the main heat exchange unit 44 is replaced with the first outdoor motor-operated valve 52. The structure of the outdoor unit 411 provided with the 2 capillary tube 52a and the 2nd non-return valve 52b is shown.

  Specifically, as shown in FIGS. 13 and 14, the outdoor unit 411 has a sixth outdoor motor-operated valve 50 and a first branch passage 50 a disposed between the supercooling heat exchanger 90 and the outdoor heat exchanger 140. To do. Moreover, the 1st-4th check valves 51b-54b and the 1st-4th capillary tubes 51a-54a are arrange | positioned between the 1st branch path 50a and each heat exchange part 41-44. The branch pipe 144a is a pipe branched from a pipe extending from the main heat exchange unit 44 to the second check valve 52b. The branch pipe 144a allows the refrigerant to flow from the main heat exchange unit 44 to the bridge circuit 155 during cooling.

  More specifically, as shown in FIG. 13, at the time of cooling, the refrigerant compressed by the high stage compression unit 22 is discharged to the second discharge pipe 22b (point I). The discharged high-pressure refrigerant passes through the second switching mechanism 32, is cooled by the main heat exchange unit 44 that functions as a gas cooler, and reaches the bridge circuit 155 through the branch pipe 144a. Thereafter, the refrigerant flows through the inlet check valve 15a of the bridge circuit 155 to the economizer heat exchanger 61 (point J).

  As shown in FIG. 14, during heating, the intermediate pressure refrigerant that has exited the supercooling heat exchanger 90 passes through the sixth outdoor motor-operated valve 50 and reaches the first branch 50a. The opening degree of the sixth outdoor motor-operated valve 50 is adjusted so that the flow of the intermediate pressure refrigerant does not drift. The first branch path 50a branches the refrigerant whose flow is adjusted by the sixth outdoor motor-operated valve 50 to the heat exchange units 41 to 44.

  In the outdoor unit 411, the expansion mechanism 70 and the sixth outdoor motor-operated valve 50 function as a first expansion mechanism that decompresses the refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating. The refrigerant sent from the indoor heat exchanger 12a to the main heat exchange unit 44 during heating is also decompressed by the second capillary tube 52a. The sixth outdoor motor operated valve 50 also functions as a second expansion mechanism that depressurizes the refrigerant sent from the indoor heat exchanger 12a to the sub heat exchange unit 41 during heating. The refrigerant sent from the indoor heat exchanger 12a to the sub heat exchanger 41 during heating is also decompressed by the expansion mechanism 70 and the first, third, and fourth capillary tubes 51a, 53a, 54a. The check valves 51b to 54b stop the flow of the refrigerant from the heat exchange units 41 to 44 to the first branch 50a during cooling. The refrigerant that has passed through the main heat exchange unit 44 flows to the indoor heat exchanger 12a via the branch pipe 144a and the bridge circuit 155.

  Also by doing in this way, the manufacturing cost of an air conditioning apparatus can be suppressed compared with the case where a motor-operated valve is provided with respect to all the sub heat exchange parts 41-43. Further, the flow adjustment can be performed more effectively by flowing the refrigerant adjusted by the sixth outdoor motor operated valve 50 through the first to fourth capillary tubes 51a to 54a.

(4-5) Modification E
In the air conditioner 110 according to the modified example B, a uniaxial four-stage compression structure in which four compression units 21 to 24 are connected to a single drive shaft is used as a multistage compression mechanism of a refrigeration apparatus that is a premise of the present invention. Although the four-stage compressor 120 is employed, it is possible to employ a compressor composed of a plurality of two-stage compressors instead.

  For example, as shown in FIG. 14, the air-conditioning apparatus 210 can be configured by employing a multi-stage compression mechanism 220 including two two-stage compressors 220a and 220b. In the air conditioner 210, an outdoor unit 511 is connected to the indoor unit 12 in place of the outdoor unit 211 according to Modification B. The only difference between the outdoor unit 211 and the outdoor unit 511 is that the former employs the four-stage compressor 120 while the latter employs the multi-stage compression mechanism 220.

  The multistage compression mechanism 220 is a compression mechanism in which a low-stage two-stage compressor 220a and a high-stage two-stage compressor 220b are connected in series. The low-stage two-stage compressor 220a is a hermetic compressor in which a low-stage compressor 21, a first middle-stage compressor 23, and a compressor drive motor (not shown) are housed in a hermetic container. is there. A compressor drive motor drives the two compression parts 21 and 23 via a drive shaft. That is, the two-stage compressor 220a has a single-shaft two-stage compression structure in which two compression units 21 and 23 are coupled to a single drive shaft. In the two-stage compressor 220a, the low-stage compression section 21 and the first middle-stage compression section 23 are connected by piping in series. The low-stage compression unit 21 sucks the refrigerant from the first suction pipe 21a and discharges the refrigerant to the first discharge pipe 21b. The first middle-stage compression unit 23 sucks the refrigerant from the third suction pipe 23a and discharges the refrigerant to the third discharge pipe 23b. The high-stage two-stage compressor 220b is a hermetic compressor in which a second middle-stage compression section 24, a high-stage compression section 22, and a compressor drive motor (not shown) are housed in a sealed container. is there. A compressor drive motor drives the two compression parts 24 and 22 via a drive shaft. That is, the two-stage compressor 220b has a uniaxial and two-stage compression structure in which the two compression units 24 and 22 are coupled to a single drive shaft. In the two-stage compressor 220b, the second middle-stage compression section 24 and the high-stage compression section 22 are connected by piping in series. The second middle stage compressor 24 sucks the refrigerant from the fourth suction pipe 24a and discharges the refrigerant to the fourth discharge pipe 24b. The high-stage compression unit 22 sucks the refrigerant from the second suction pipe 22a and discharges the refrigerant to the second discharge pipe 22b.

  In the air conditioner 210 that employs such a multistage compression mechanism 220 as well as the air conditioner 110 according to the modified example B, it is possible to suppress both the manufacturing cost and the complicated control of the motor-operated valve. is there.

10, 100, 110, 210 Air conditioner (refrigeration equipment)
12a Indoor heat exchanger (use side heat exchanger)
20 Two-stage compressor (multi-stage compression mechanism)
21 Low stage compression section (first compression section)
22 High-stage compression section (third compression section)
23 1st middle stage compression part (2nd compression part)
24 Second middle compression section (second compression section)
31 1st switching mechanism 32 2nd switching mechanism 33 3rd switching mechanism 34 4th switching mechanism 40,140 Outdoor heat exchanger 41 1st sub heat exchange part (1st heat source side sub heat exchange part)
42,43 2nd and 3rd sub heat exchange part (2nd heat source side sub heat exchange part)
44 Main heat exchanger (Heat source side main heat exchanger)
50 Sixth outdoor motor operated valve (first expansion mechanism, second expansion mechanism)
50a First branch 51a First capillary tube 51b First check valve 52 First outdoor motor operated valve (first expansion mechanism)
52a Second capillary tube 52b Second check valve 53a Third capillary tube (first capillary tube)
53b Third check valve (first check valve)
54a Fourth capillary tube (first capillary tube)
54b Fourth check valve (first check valve)
55,155 Bridge circuit 70 Expansion mechanism (first expansion mechanism)
120,220 Four-stage compressor (multi-stage compression mechanism)
141a First intercooler pipe (suction pipe)
142a Second intercooler pipe (suction pipe)
143a Third intercooler pipe (suction pipe)

JP 2009-229051 A

Claims (4)

A multi-stage compression mechanism (20) in which a plurality of compression units are connected in series;
A heat source side main heat exchange section (44) that cools the refrigerant discharged from the most downstream compression section among the plurality of compression sections during the cooling operation, and functions as a refrigerant evaporator during the heating operation;
Heat source side sub heat exchange that cools the refrigerant that is discharged from the former compression unit among the plurality of compression units during the cooling operation and sucked into the next compression unit, and functions as an evaporator of the refrigerant during the heating operation Part (41);
A use-side heat exchange unit (12a) that functions as an evaporator that evaporates a low-pressure refrigerant during cooling and functions as a radiator that radiates heat from the high-pressure refrigerant during heating;
The refrigerant sent from the heat source side main heat exchange unit to the use side heat exchange unit during cooling is depressurized, and the refrigerant sent from the use side heat exchange unit to the heat source side main heat exchange unit during heating is depressurized. An expansion mechanism (70, 52, 50);
First, the flow of the refrigerant from the heat source side sub heat exchange unit to the use side heat exchange unit is stopped during cooling, and the refrigerant flow from the use side heat exchange unit to the heat source side sub heat exchange unit is allowed during heating. A check valve (51b);
A first capillary tube (50a) for decompressing a refrigerant sent from the use side heat exchange unit to the heat source side sub heat exchange unit during heating;
Comprising
Refrigeration equipment (10). The multi-stage compression mechanism includes a front-stage low-stage compression section (21), a higher-stage middle-stage compression section (23, 24) than the low-stage compression section, and a rearmost-stage high-stage compression section (22). And
The heat source side main heat exchange unit cools the refrigerant discharged from the high-stage compression unit,
The heat source side sub heat exchange section is
A first heat source side sub heat exchange section (41) for cooling the refrigerant discharged from the first compression section;
A second heat source side sub heat exchange part (42) for cooling the refrigerant discharged from the second compression part;
Have
The first check valve and the first capillary tube are arranged on the refrigerant inflow side during heating with respect to each of the first heat source side sub heat exchange unit and the second heat source side sub heat exchange unit,
From the first check valve and the first capillary tube and the first heat source side sub heat exchange part or the second heat source side sub heat exchange part to the middle stage compression part or the high stage compression part A suction pipe (141a to 143a) for returning the refrigerant;
During the cooling operation, the refrigerant is sent from the heat source side main heat exchanger to the use side heat exchanger, and during the heating operation, the heat source side main heat exchanger and the heat source side sub heat exchange unit from the use side heat exchanger. A switching mechanism (31, 32) that switches the state so that the refrigerant is sent to
Further comprising
The refrigeration apparatus according to claim 1. A second expansion mechanism (70, 50) for reducing the pressure of the refrigerant sent from the use side heat exchange unit to the heat source side sub heat exchange unit during heating;
A branch path (50a) for branching the refrigerant decompressed by the second expansion mechanism to each of the first heat source side sub heat exchange unit and the second heat source side sub heat exchange unit;
Further comprising
The refrigeration apparatus according to claim 2. Secondly, the flow of the refrigerant from the heat source side main heat exchange unit to the use side heat exchange unit is stopped during cooling, and the refrigerant flow from the use side heat exchange unit to the heat source side main heat exchange unit is allowed during heating. A check valve (52b);
A second capillary tube (52a) for decompressing the refrigerant sent from the use side heat exchange unit to the heat source side main heat exchange unit during heating;
A branch path (50a) for branching the refrigerant decompressed by the first expansion mechanism to each of the heat source side main heat exchange unit and the heat source side sub heat exchange unit;
Further comprising
The refrigeration apparatus according to claim 1.

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