JP2011214758A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize a pressure inside of a stopped compressing section of which driving is stopped, in a case that the plurality of compressing sections having a plurality of compressing elements are arranged in parallel with each other.SOLUTION: A compressing mechanism 3 is constituted by connecting compressors 31, 32 having low-pressure compressing elements 31e, 32e and high-pressure compressing elements 31d, 32d in parallel with each other. A refrigerant of high pressure discharged from each of the high-pressure compressing elements 31d, 32d flows in a high-pressure pipe p1. An intermediate pipe p2 connects the high-pressure compressing elements 31d, 32d and the low-pressure compressing elements 31e, 32e, and a refrigerant of intermediate pressure flows therein. In a low-pressure pipe p3, a refrigerant of low pressure sucked to the low-pressure compressing elements 31e, 32e flows. A regulation valve 8 regulates a communication state of the stopped compressor 32 and the pipes p1, p2, p3, so that the refrigerant is allowed to flow only in one of the pipes p1, p2, p3, and does not flow to the other pipes in the stopped compressor 32, in a case when the compressor 32 is stopped and the compressor 31 is driven.

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus provided with a compression mechanism in which a plurality of compression units having a plurality of compression elements are connected in parallel.

  Conventionally, there is one disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-133583) as one of refrigeration apparatuses that perform a multistage compression refrigeration cycle. The refrigeration apparatus according to Patent Document 1 includes two compression units having a high-pressure compression element and a low-pressure compression element, and the refrigerant discharged from the low-pressure compression element of each compression unit is once merged and then branched. Sucked into the high pressure compression element of the compression section. A bypass shut-off valve is provided on the path connecting the low pressure compression element, the intermediate cooler, and the high pressure compression element, and between the intermediate cooler and the high pressure compression element, for blocking the refrigerant flow. Furthermore, a high-pressure suction shut-off valve is provided on another path until the refrigerant discharged from the low-pressure compression element branches from the path near the discharge port of the low-pressure compression element and is sucked into the high-pressure compression element of each compression unit. Is provided.

  In the above-mentioned Patent Document 1, a high-pressure intake shut-off valve immediately before the stop compression unit starts to start from a state in which one compression unit is driven and the other compression unit (hereinafter referred to as a stop compression unit) is stopped. By closing the valve and opening the bypass shut-off valve, the refrigerant can easily reach the high-pressure compression element. However, in the said patent document 1, when the stop compression part has stopped drive, the inside of the dome of a stop compression part cannot necessarily be made into a pressure equalization state. If the pressure inside the dome of the stop compression section is not equal, refrigerant may flow from the stop compression section to the outside of the compression section, or from the outside of the stop compression section to the dome of the compression section, depending on the pressure difference that occurs. And refrigeration oil may flow out.

  Therefore, an object of the present invention is to equalize the inside of the dome of the stop compression unit in a state where driving is stopped when a plurality of compression units having a plurality of compression elements are connected in parallel.

  The refrigeration apparatus according to the first aspect of the present invention includes a compression mechanism, a heat source side heat exchanger, an expansion mechanism, a use side heat exchanger, a high pressure pipe, a medium pressure pipe, a low pressure pipe, and a regulating valve. The compression mechanism is configured by connecting a plurality of compression units in parallel. Each compression section includes a low-pressure compression element that increases the pressure of the refrigerant and a high-pressure compression element that increases the pressure of the refrigerant further than the low-pressure compression element. The heat source side heat exchanger functions as a refrigerant cooler or heater. The expansion mechanism depressurizes the refrigerant. The use side heat exchanger functions as a refrigerant heater or cooler. High-pressure refrigerant discharged from the high-pressure compression elements of the plurality of compression units flows through the high-pressure pipe. The medium pressure pipe connects the high pressure compression element and the low pressure compression element in each compression section, and the medium pressure refrigerant flows. Low-pressure refrigerant sucked into the low-pressure compression elements of the plurality of compression units flows through the low-pressure pipe. When any one of the plurality of compression units (hereinafter referred to as a stop compression unit) stops driving and the remaining compression units are driven, the regulating valve has a high pressure pipe, an intermediate pressure pipe, The state of communication between the stop compressor and each pipe is adjusted so that only one of the low-pressure pipes allows the refrigerant to flow and does not flow between the other pipes.

  In this refrigeration apparatus, any one of the plurality of compression units has stopped driving, and in the state in which the other compression units are driving, each of the compression units stopped driving by the adjusting valve The refrigerant flows between any one of the pipes (specifically, the high-pressure pipe, the medium-pressure pipe, and the low-pressure pipe), and the refrigerant does not flow with the other pipes. For example, when the adjustment valve causes the refrigerant to flow only between the stop compressor and the medium pressure pipe, the refrigerant does not flow between the other high-pressure pipes or low-pressure pipes and the stop compressor. In this case, between the intermediate pressure pipes, that is, between the low pressure compression element and the high pressure compression element in the stop compression section, and in the dome of the stop compression section are filled with the refrigerant having the same pressure. Therefore, no pressure difference is generated between the intermediate pipe and the inside of the dome, and the inside of the stop compression section is kept at a uniform pressure.

  The refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect, wherein each compression unit is a compressor containing a high pressure compression element and a low pressure compression element in one dome.

  In this refrigeration apparatus, the stop compression section is composed of a single compressor in which a high pressure compression element and a low pressure compression element are accommodated in one dome. Therefore, it is possible to equalize the pressure inside the dome without causing a refrigerant flow from the stop compression unit to the other compression unit.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the first or second aspect, wherein the stop compression unit is configured such that the refrigerant discharged from the high pressure compression element or the low pressure compression element of the stop compression unit is in the dome. Stop driving in full condition. The regulating valve has a low-pressure check valve that allows only the flow of refrigerant from the low-pressure pipe toward the stop compressor.

  When the refrigerant discharged from the high pressure compression element is filled in the dome of the stop compression unit, the high pressure refrigerant is filled in the dome of the stop compression unit. In addition, when the refrigerant discharged from the low pressure compression element is filled in the dome of the stop compression unit, the medium pressure refrigerant is filled in the dome of the stop compression unit. On the other hand, since the low-pressure refrigerant flows into the low-pressure pipe side, in the vicinity of the low-pressure refrigerant inlet of the stop compression section where the high-pressure or medium-pressure refrigerant is filled, Due to this pressure difference, the refrigeration oil may flow out from the high pressure stop compression section to the low pressure low pressure piping side.

  However, in this refrigeration apparatus, only the refrigerant flow from the low pressure pipe toward the stop compression section is allowed by the low pressure side check valve, and conversely, the refrigerant flow from the stop compression section to the low pressure pipe is blocked. . As a result, even if there is a pressure difference between the inside of the dome of the stop compression section and the inside of the low pressure pipe, the refrigerant and the accompanying refrigeration oil flow from the high pressure stop compression section to the low pressure low pressure pipe side. Can be prevented.

  The refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to the third aspect, wherein the stop compression unit stops driving in a state where the refrigerant discharged from the low pressure compression element of the stop compression unit is filled in the dome. To do. The regulating valve further includes an intermediate pressure side check valve and a high pressure side check valve. The intermediate pressure check valve allows only the refrigerant flow from the low pressure compression element to the high pressure compression element of the stop compression section in the medium pressure pipe. The high pressure side check valve allows only the flow of refrigerant from the stop compression section toward the high pressure pipe.

  When the refrigerant discharged from the low pressure compression element is filled in the dome of the stop compression section, the medium pressure refrigerant is filled in the dome of the stop compression section. On the other hand, medium-pressure refrigerant flows into the medium-pressure pipe, and high-pressure refrigerant flows into the high-pressure pipe. Then, immediately after stopping the stop compression section, depending on the pressure in the dome of the compression section, there is a pressure difference between the inside of the dome of the stop compression section and the medium pressure pipe or the high pressure pipe. There is a risk that the refrigeration oil flows out from the compression section to the medium pressure pipe or the high pressure pipe.

  However, in this refrigeration system, only the refrigerant flow from the low pressure compression element to the high pressure compression element of the stop compression section is allowed by the intermediate pressure side check valve, and conversely, the refrigerant flow from the high pressure compression element to the low pressure compression element is Blocked. Further, only the refrigerant flow from the stop compression section to the high pressure pipe is allowed by the high pressure side check valve, and conversely, the refrigerant flow from the high pressure pipe to the stop compression section through the intermediate pressure pipe is blocked. As a result, in the stop compression section where the inside of the dome becomes medium pressure when the drive is stopped, the refrigerant and the accompanying refrigeration oil flow out from the high pressure compression element to the low pressure compression element, and from the stop compression section to the high pressure piping side. Can be prevented.

  In particular, in the stop compression section in which the inside of the dome has an intermediate pressure when driving is stopped, all the adjustment valves can be configured by check valves. Therefore, the flow of the refrigerant can be adjusted with a simple configuration, and the cost can be suppressed as compared with the case where the adjustment valve is configured by an electromagnetic valve or the like.

  The refrigeration apparatus according to the fifth aspect of the present invention is the refrigeration apparatus according to any one of the first to third aspects, wherein the adjustment valve further includes a closing valve. The shutoff valve is provided in the intermediate pressure pipe in which the direction in which the refrigerant flows out in the state where the stop compression unit stops driving is the same as that in the drive state of the stop compression unit due to the pressure relationship of the refrigerant.

  In this refrigeration system, due to the pressure relationship of the refrigerant, the check valve is not used for an intermediate pressure pipe in which the direction in which the refrigerant flows out when the stop compressor is stopped is the same as when the stop compressor is driven. A shut-off valve is provided. The shut-off valve takes a “closed” state when the stop compression unit stops driving, and takes an “open” state when the stop compression unit is driven. Thereby, when a stop compression part stops a drive, the outflow of a refrigerant | coolant can be prevented reliably.

  The refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to the fifth aspect, wherein the stop valve stops driving in a state where the stop compression unit is filled with the refrigerant discharged from the high pressure compression element. When the operation is stopped when the dome is filled with the refrigerant sucked from the low pressure side suction pipe, the medium pressure pipe is provided.

  In this refrigeration apparatus, the shut-off valve is provided in the medium pressure pipe when the inside of the dome of the stop compression unit is filled with high-pressure refrigerant or when it is filled with low-pressure refrigerant. Therefore, when the stop compressor stops driving in a high pressure state or a low pressure state, it is possible to reliably prevent the refrigerant from flowing out.

  A refrigeration apparatus according to a seventh aspect of the present invention includes a compression mechanism, a heat source side heat exchanger, an expansion mechanism, a use side heat exchanger, a high pressure pipe, a first medium pressure pipe, and a second medium pressure pipe. And a low-pressure pipe and a regulating valve. The compression mechanism is configured by connecting a plurality of compression units in parallel. Each compression section has a low pressure compression element, an intermediate pressure compression element, and a high pressure compression element. The low pressure compression element increases the pressure of the refrigerant. The medium pressure compression element increases the refrigerant pressure further than the low pressure compression element. The high pressure compression element increases the pressure of the refrigerant further than the medium pressure compression element. The heat source side heat exchanger functions as a refrigerant cooler or heater. The expansion mechanism depressurizes the refrigerant. The use side heat exchanger functions as a refrigerant heater or cooler. High-pressure refrigerant discharged from the high-pressure compression elements of the plurality of compression units flows through the high-pressure pipe. The first intermediate pressure pipe connects the intermediate pressure compression element and the high pressure compression element in each compression section. The second intermediate pressure pipe connects the intermediate pressure compression element and the low pressure compression element in each compression section. Low-pressure refrigerant sucked into the low-pressure compression elements of the plurality of compression units flows through the low-pressure pipe. When any one of the plurality of compression units (hereinafter referred to as a stop compressor) stops driving and the remaining compression units are driven, the adjustment valve is connected to the high-pressure pipe, the first intermediate pressure in the stop compression unit. The communication state between the stop compressor and each pipe is set so that only one of the pipe, the second medium-pressure pipe and the low-pressure pipe is allowed to flow the refrigerant, and no refrigerant flows between the other pipes. adjust.

  The compression unit according to this refrigeration apparatus has three stages of a low pressure compression element, an intermediate pressure compression element, and a high pressure compression element. In this case, in the state where any one of the plurality of compression units has stopped driving and the other compression units are driving, the compression unit that has stopped driving and each pipe ( Specifically, the refrigerant flows between any one of the high-pressure pipe, the first medium-pressure pipe, the second medium-pressure pipe, and the low-pressure pipe, and the refrigerant does not flow with the other pipes. For example, when the flow of the refrigerant is generated only between the stop compression unit and the first intermediate pressure pipe by the adjusting valve, the other high pressure pipe, the second intermediate pressure pipe, the low pressure pipe, and the stop compression part In between, the refrigerant stops flowing. In this case, between the first intermediate pressure pipes, that is, between the intermediate pressure compression element and the high pressure compression element in the stop compression section, and in the dome of the stop compression section, the refrigerant of the same pressure is filled. Therefore, no pressure difference is generated between the first intermediate pipe and the inside of the dome, and the inside of the stop compressor is kept at a uniform pressure. That is, even when a plurality of compression units having three-stage compression elements are connected in parallel, the inside of the stop compression unit can be equalized.

  The refrigeration apparatus according to an eighth aspect of the present invention is the refrigeration apparatus according to the seventh aspect, wherein the compression unit has a plurality of medium pressure compression elements. And this freezing apparatus is further provided with 1 or several 3rd intermediate pressure piping which connects the intermediate pressure compression elements of each compression part. The regulating valve allows the refrigerant to flow only in one of the high pressure pipe, the first medium pressure pipe, the second medium pressure pipe, the low pressure pipe, and one or a plurality of third medium pressure pipes in the stop compression unit, The state of communication between the stop compressor and each pipe is adjusted so that no refrigerant flows between the other pipes.

  The compression unit according to this refrigeration apparatus has four or more stages of compression elements. Thus, even when a plurality of compression units having four or more stages of compression elements are connected in parallel, the inside of the stop compression unit can be equalized.

  According to the refrigeration apparatus according to the first aspect of the present invention, no pressure difference is generated between the intermediate pipe and the inside of the dome, and the inside of the stop compression section is kept at a uniform pressure.

  According to the refrigeration apparatus according to the second aspect of the present invention, the inside of the dome can be equalized without causing a refrigerant flow from the stop compression section to the other compression section.

  According to the refrigeration apparatus according to the third aspect of the present invention, even when there is a pressure difference between the inside of the dome of the stop compression section and the inside of the low pressure pipe, the stop compression section having a high pressure is moved to the low pressure pipe side having a low pressure. The refrigerant and the accompanying refrigeration oil can be prevented from flowing out.

  According to the refrigeration apparatus according to the fourth aspect of the present invention, in the stop compression section where the inside of the dome has an intermediate pressure when the drive is stopped, the refrigerant and the It is possible to prevent the refrigerating machine oil from flowing out. In particular, in this case, the flow of the refrigerant can be adjusted with a simple configuration in which the adjustment valve is only a check valve, and the cost can be reduced compared to the case where the adjustment valve is constituted by an electromagnetic valve or the like.

  According to the refrigeration apparatus according to the fifth aspect of the present invention, when the stop compressor stops driving, the refrigerant can be reliably prevented from flowing out.

  According to the refrigeration apparatus according to the sixth aspect of the present invention, when the stop compressor stops driving in a high pressure state or a low pressure state, the refrigerant can be reliably prevented from flowing out.

  According to the refrigeration apparatus according to the seventh aspect of the present invention, even when a plurality of compression units having three-stage compression elements are connected in parallel, the inside of the stop compression unit can be equalized.

  According to the refrigeration apparatus according to the eighth aspect of the present invention, even when a plurality of compression units having four or more stages of compression elements are connected in parallel, the inside of the stop compression unit can be equalized.

It is a schematic block diagram of the air conditioning apparatus as one Embodiment of the freezing apparatus concerning this invention. FIG. 4 is a pressure-enthalpy diagram illustrating a refrigeration cycle during cooling operation. FIG. 3 is a temperature-entropy diagram illustrating a refrigeration cycle during cooling operation. It is a schematic block diagram of the air conditioning apparatus concerning the modification A. It is a schematic block diagram of the air conditioning apparatus concerning the modification B. It is a schematic block diagram of the air conditioning apparatus concerning the modification C. It is a schematic block diagram of the air conditioning apparatus concerning the modification D. It is a schematic block diagram of the air conditioning apparatus concerning the modification E. It is a schematic block diagram of the air conditioning apparatus concerning the modification F. It is a schematic block diagram of the air conditioning apparatus concerning the modification G. It is a schematic block diagram of the air conditioning apparatus concerning the modification H. It is a figure showing the outline of other composition, omitting a heat source side heat exchanger, an expansion mechanism, and a use side heat exchanger among the air harmony devices concerning modification I. It is a schematic block diagram of the air conditioning apparatus in the air conditioning apparatus concerning the modification J.

  Hereinafter, the refrigeration apparatus of the present invention will be described with reference to the drawings.

(1) Configuration FIG. 1 is a schematic configuration diagram of an air conditioner 1 as an embodiment of a refrigeration apparatus according to the present invention. The air conditioner 1 includes a refrigerant circuit 2 configured to be capable of cooling operation, and performs a two-stage compression refrigeration cycle using a refrigerant (here, carbon dioxide) that operates in a supercritical region. Device.

  The refrigerant circuit 2 of the air conditioner 1 mainly includes a compression mechanism 3, oil separation mechanisms 21, 22, 25, 26, a high pressure pipe p 1, an intermediate pressure pipe p 2, a low pressure pipe p 3, a heat source side heat exchanger 4, and an expansion mechanism 5. , A use side heat exchanger 6, an intermediate cooler 7, and a regulating valve 8.

(1-1) Compression mechanism In this embodiment, the compression mechanism 3 is configured by connecting in parallel two compressors 31 and 32 (corresponding to compression units) that compress refrigerant in two stages with two compression elements. ing. The compressors 31 and 32 are sealed in which compressor drive motors 31b and 32b, drive shafts 31c and 32c, and two compression elements 31d, 31e, 32d, and 32e are accommodated in one dome 31a and 32a, respectively. It has a formula structure. The compressor drive motors 31b and 32b are connected to the drive shafts 31c and 32c, respectively. The drive shafts 31c and 32c are connected to the two compression elements 31d and 31e in the dome 31a and the two compression elements 32d and 32e in the dome 32a, respectively. That is, the drive shaft 31c is a common shaft for the two compression elements 31d and 31e in the dome 31a, and the compressor 31 is rotationally driven by the compressor drive motor 31b for the two compression elements 31d and 31e. This is a so-called uniaxial two-stage compression structure that performs compression work. Similarly, the two compression elements 32d and 32e in the dome 32a are connected to a single drive shaft 32c, and the compressor 32 is rotationally driven by the compressor drive motor 32b. As a result, a so-called uniaxial two-stage compression structure that performs compression work is obtained. The compression elements 31d, 31e, 32d, and 32e are positive displacement compression elements such as a rotary type and a scroll type in the present embodiment. Specifically, the compression elements 31d, 31e, 32d, and 32e are low-pressure compression elements 31e and 32e that increase the pressure of the refrigerant, and high-pressure compression elements 31d and 32d that further increase the pressure of the refrigerant than the low-pressure compression elements 31e and 32e. Composed.

  The compressor 31 has a suction port of a low-pressure compression element 31e connected to one end of a low-pressure suction pipe p31a branched from a low-pressure pipe p3 described later, and a compressor connected to one end of a high-pressure discharge pipe p11a branched from the high-pressure pipe p1. 31 discharge ports are connected. The compressor 31 has a discharge port of the low-pressure compression element 31e connected to one end of the discharge-side intermediate pressure branch pipe p21 that joins the discharge-side intermediate pressure mother pipe p23 of the intermediate pressure pipe p2, and the suction side of the intermediate pressure pipe p2 The suction port of the high-pressure compression element 31d is connected to one end of the suction-side medium pressure branch pipe p25 branched from the medium pressure mother pipe p24. Similarly, in the compressor 32, the suction port of the low pressure compression element 32e is connected to one end of the low pressure suction pipe p32a branched from the low pressure pipe p3, and the compressor 32 is connected to one end of the high pressure discharge pipe p12a branched from the high pressure pipe p1. The outlet is connected. The compressor 32 has a discharge side of the low pressure compression element 32e connected to one end of the discharge side intermediate pressure branch pipe p22 that joins the discharge side intermediate pressure mother pipe p23, and is branched from the suction side intermediate pressure mother pipe p24. The suction port of the high pressure compression element 32d is connected to one end of the intermediate pressure branch pipe p26.

  With the above-described configuration, the low-pressure refrigerant is sucked into the low-pressure compression elements 31e and 32e of the compressors 31 and 32 through the low-pressure pipe p3 and the low-pressure side suction pipes p31a and p32a. Then, the low-pressure refrigerant is compressed by the low-pressure compression elements 31e and 32e and further compressed by the high-pressure compression elements 31d and 32d, thereby becoming a high-pressure state. Thereafter, the high-pressure refrigerant is discharged from each of the high-pressure discharge pipes p11a and p12a and merges in the high-pressure pipe p1. The compression mechanism 3 compresses the low-pressure refrigerant sucked from the low-pressure suction pipes p31a and p32a by the low-pressure compression elements 31e and 32e in the course of sucking the refrigerant from the low-pressure pipe p3 and discharging the refrigerant from the high-pressure pipe p1. After the pressure is reached, the refrigerant is discharged from the discharge ports of the low pressure compression elements 31e and 32e to one intermediate pressure pipe p2, and then sucked from the suction ports of the high pressure compression elements 31d and 32d.

  Thus, in this embodiment, the compression mechanism 3 has the four compression elements 31d, 31e, 32d, and 32e, the low pressure compression element 31e and the high pressure compression element 31d are connected in series, and the low pressure compression element 32e. The high-pressure compression element 32d is connected in series. Further, the high pressure compression elements 31d and 32d are connected in parallel to each other, and the low pressure compression elements 31e and 32e are connected in parallel to each other. The compression mechanism 3 then compresses the refrigerant compressed to the medium pressure by the low-pressure compression elements 31e and 32e, which are the compression elements on the front stage among the compression elements 31d, 31e, 32d and 32e, on the downstream side. The high pressure compression elements 31d and 31e, which are elements, are configured to be sequentially compressed to a higher pressure.

  Further, among the two-stage compression elements 31d and 31e included in the compressor 31, when the compressor 31 is driven, the medium-pressure refrigerant discharged from the low-pressure compression element 31e as the previous stage is a compressor having the element 31e. 31 is discharged outside the dome 31a through the intermediate pressure pipe p2 (specifically, the discharge side intermediate pressure branch pipe p21). Therefore, the low pressure compression element 31e corresponds to an external discharge compression element. When the compressor 31 is driven, the high-pressure refrigerant discharged from the high-pressure compression element 31d, which is the latter stage, is once discharged into the dome 31a of the compressor 31, and then through the high-pressure discharge pipe p11a directly connected to the dome 31a. The ink is discharged to the outside of the dome 31a, specifically, to the oil separation mechanism 21 side. Accordingly, the high pressure compression element 31d corresponds to an internal discharge compression element. Similarly, when the compressor 32 is driven, the medium-pressure refrigerant discharged from the low-pressure compression element 32e, which is the preceding stage, of the two-stage compression elements 32d and 32e included in the compressor 32 has the element 32e. It is discharged out of the dome 32a of the compressor 32 through an intermediate pressure pipe p2 (specifically, a discharge side intermediate pressure branch pipe p22). Accordingly, the low pressure compression element 32e corresponds to an external discharge compression element. When the compressor 32 is driven, the high-pressure refrigerant discharged from the subsequent high-pressure compression element 32d is once discharged into the dome 32a of the compressor 32, and then via the high-pressure discharge pipe p12a directly connected to the dome 32a. The ink is discharged to the outside of the dome 32a, specifically, to the oil separation mechanism 22 side. Accordingly, the high pressure compression element 32e corresponds to an internal discharge compression element. From the above, it can be said that the compressors 31 and 32 according to the present embodiment are so-called high-pressure dome type compressors in which high-pressure refrigerant is accumulated in the respective domes 31a and 32a during driving.

(1-2) Oil separation mechanism The oil separation mechanisms 21, 22, 25, and 26 are mechanisms for separating the refrigerating machine oil accompanying the refrigerant. In the present embodiment, the oil separation mechanisms 21, 22, 25, 26 correspond to the low pressure compression elements 31e, 32e and the high pressure compression elements 31d, 32d of the compressors 31, 32, respectively. , 31e, 32e are provided on the discharge side.

  The oil separation mechanisms 21 and 22 have oil separators 21a and 22a, oil return pipes 21c and 22c, and pressure reduction mechanisms 21b and 22b, respectively. The oil separators 21a and 22a separate the refrigerating machine oil accompanying the refrigerant from the high-pressure refrigerant discharged from the high-pressure compression elements 31d and 32d, which are internal discharge compression elements of the compressors 31 and 32, respectively. One end of each oil return pipe 21c, 22c is connected to each oil separator 21a, 22a, and the refrigerating machine oil separated by each oil separator 21a, 22a is supplied to the internal discharge compression element, that is, each high pressure compression element. Return to the suction side of 31d and 32d. In particular, the oil return pipe 21c according to the present embodiment is not a compressor 31 having a high-pressure compression element 31d that is a refrigerant flow source from which the refrigerating machine oil separated by the oil separator 21a is discharged. Return to the suction side of the high-pressure compression element 32d of another compressor 32 (that is, the internal discharge compression element of the compressor 32). Therefore, the other end of the oil return pipe 21c is connected to the suction side intermediate pressure branch pipe p26 of the intermediate pressure pipe p2. Similarly, the oil return pipe 22c according to the present embodiment includes a compressor 32 having a high-pressure compression element 32d that is a refrigerant flow source from which the refrigerating machine oil separated by the oil separator 22a is transferred. Instead, it is returned to the suction side of the high-pressure compression element 31d of another compressor 31 (that is, the internal discharge compression element of the compressor 31). Therefore, the other end of the oil return pipe 22c is connected to the suction side intermediate pressure branch pipe p25 of the intermediate pressure pipe p2. That is, the oil return pipes 21c and 22c according to the present embodiment and the suction side intermediate pressure branch pipes p25 and p26 in the intermediate pressure pipe p2 are connected in a so-called staking state. The decompression mechanisms 21b and 22b decompress the refrigerating machine oil flowing through the oil return pipes 21c and 22c. The decompression mechanisms 21b and 22b are provided on the oil return pipes 21c and 22c, and a capillary tube is used in this embodiment.

  Thus, in this embodiment, the suction side intermediate pressure branch pipes p25 and p26 and the high pressure discharge pipes p11a and p12a are connected to each other by the oil separation mechanisms 21 and 22. Therefore, the high-pressure refrigerant discharged from the high-pressure compression element 31d due to a bias generated between the amount of refrigerating machine oil accumulated in the high-pressure compression element 31d and the amount of refrigerating machine oil accumulated in the high-pressure compression element 32d. Even if there is a bias between the amount of refrigeration oil in the refrigerant and the amount of refrigeration oil in the high-pressure refrigerant discharged from the high-pressure compression element 32d, the amount of refrigeration oil in the high-pressure compression elements 31d and 32d As a result, the amount of refrigerating machine oil returns to the direction where there is a smaller amount, and the unevenness of the amount of refrigerating machine oil accumulated in the high-pressure compression elements 31d and 32d is eliminated.

  The oil separation mechanisms 25 and 26 have oil separators 25a and 26a, oil return pipes 25c and 26c, and pressure reduction mechanisms 25b and 26b, respectively. Each of the oil separators 25a and 26a is provided on the medium pressure pipe p2, and from the medium pressure refrigerant discharged from the low pressure compression elements 31e and 32e, which are external discharge compression elements of the compressors 31 and 32, respectively. The refrigerating machine oil accompanying the refrigerant is separated. One end of each of the oil return pipes 25c and 26c is connected to the oil separators 25a and 26a, and the refrigerating machine oil separated by each of the oil separators 25a and 26a is supplied to the internal discharge compression element, that is, each high-pressure compression element 31d. , 32d to the suction side. Specifically, the oil return pipe 25c differs from the oil return pipe 21c in that the refrigerating machine oil separated by the oil separator 25a is supplied with the low-pressure compression element 31e that is the refrigerant flow source accompanied by the refrigerating machine oil. The compressor 31 itself is returned to the suction side of the high-pressure compression element 31d that is the internal discharge compression element of the compressor 31. Therefore, the other end of the oil return pipe 25c is connected to the suction side intermediate pressure branch pipe p25 of the intermediate pressure pipe p2. Similarly, unlike the oil return pipe 22c, the oil return pipe 26c has a low-pressure compression element 32e, which is a refrigerant flow source from which the refrigerating machine oil was accompanied by the refrigerating machine oil separated by the oil separator 26a. It is returned to the suction side of the compressor 32 itself and to the suction side of the high-pressure compression element 32d which is an internal discharge compression element of the compressor 32. Therefore, the other end of the oil return pipe 26c is connected to the suction side intermediate pressure branch pipe p26 of the intermediate pressure pipe p2. That is, the oil return pipes 25c and 26c and the suction side intermediate pressure branch pipes p25 and p26 in the intermediate pressure pipe p2 are not in a so-called stagnation state, and the compressors 31 and 32 themselves corresponding to the oil return pipes 25c and 26c correspond to each other. The refrigerating machine oil is connected so as to return to the suction side of the internal discharge compression element. The decompression mechanisms 25b and 26b decompress the refrigerating machine oil flowing through the oil return pipes 25c and 26c. The decompression mechanisms 25b and 26b are provided on the oil return pipes 25c and 26c, and a capillary tube is used in this embodiment.

(1-3) Various pipes The high-pressure pipe p1 has one end connected to the junction of discharge branch pipes p11b and p12b connected to the discharge port side of each oil separation mechanism 21, 22, and the other end is a heat source side heat exchanger. 4 is connected. High-pressure refrigerant discharged from the high-pressure compression elements 31d and 32d of the two compressors 31 and 32 flows through the high-pressure pipe p1. That is, high-pressure refrigerant that is discharged into the domes 31a and 32a of the compressors 31 and 32 and separated from the refrigerating machine oil flows through the high-pressure pipe p1. The high-pressure refrigerant is sent to the heat source side heat exchanger 4 through the high-pressure pipe p1.

  The medium pressure pipe p2 connects the high pressure compression elements 31d and 32d and the low pressure compression elements 31e and 32e in the compressors 31 and 32, respectively. Specifically, the other end of the discharge-side intermediate pressure branch pipe p21 whose one end is connected to the discharge port of the low-pressure compression element 31e is connected to the oil separation mechanism 25 and the stop valve 83 at one end side of the intermediate-pressure pipe p2. It is connected to one end side of the discharge side intermediate pressure mother pipe p23 via (described later). The other end of the discharge-side intermediate pressure branch pipe p22, which has one end connected to the discharge port of the low-pressure compression element 32e, is connected to the oil separation mechanism 26 and the stop valve 84 (described later). Is connected to one end side of the discharge-side intermediate pressure mother pipe p23. On the other hand, at the other end of the intermediate pressure pipe p2, one end of the suction side intermediate pressure branch pipe p25 connected to the suction port of the high pressure compression element 31d is connected to the other end side of the suction side intermediate pressure mother pipe p24. One end of the suction side intermediate pressure branch pipe p26 connected to the other end of the suction port of the high pressure compression element 32d is connected to the other end side of the suction side intermediate pressure mother pipe p24. An intermediate pressure refrigerant flows between the suction side intermediate pressure branches p25 and p26 as the same pressure refrigerant.

  One end of the low-pressure pipe p3 is connected to the other end of the use side heat exchanger 6, and the other end of the low-pressure pipe p3 is connected to a junction of the low-pressure suction pipes p31a and p32a of the compressors 31 and 32. In the low-pressure pipe p3, low-pressure refrigerant sucked into the low-pressure compression elements 31e and 32e of the compressors 31 and 32 flows. That is, when the low-pressure refrigerant flows from the use-side heat exchanger 6 to the low-pressure pipe p3, the refrigerant flows separately into the low-pressure suction pipes p31a and p32a, and flows from the suction ports of the low-pressure compression elements 31e and 32e to the low-pressure compression elements 31e and 32e. Flows into the interior.

(1-4) Heat source side heat exchanger The heat source side heat exchanger 4 is a heat exchanger that functions as a refrigerant cooler. One end of the heat source side heat exchanger 4 is connected to the pipes p11b and p11a of the compression mechanism 3 via the high-pressure pipe p1 and the other end is connected to one end of the expansion mechanism 5. Although not shown here, the heat source side heat exchanger 4 is supplied with water or air as a cooling source for exchanging heat with the refrigerant flowing through the heat source side heat exchanger 4.

(1-5) Expansion mechanism The expansion mechanism 5 is a mechanism that depressurizes the refrigerant, and an electric expansion valve is used in the present embodiment. One end of the expansion mechanism 5 is connected to the heat source side heat exchanger 4, and the other end is connected to the use side heat exchanger 6. In the present embodiment, the expansion mechanism 5 reduces the pressure of the high-pressure refrigerant cooled in the heat source side heat exchanger 4 functioning as a radiator before being sent to the use side heat exchanger 6 functioning as an evaporator.

(1-6) Use-side heat exchanger The use-side heat exchanger 6 is a heat exchanger that functions as a refrigerant heater. One end of the use side heat exchanger 6 is connected to the other end of the expansion mechanism 5, and the other end of the use side heat exchanger 6 is connected to the suction side of the compression mechanism 3 via the low pressure pipe p3. . Although not shown here, the use side heat exchanger 6 is supplied with water and air as a heat source for exchanging heat with the refrigerant flowing through the use side heat exchanger 6.

(1-7) Intermediate cooler The intermediate cooler 7 is provided on the intermediate pressure pipe p2. Specifically, one end of the intermediate cooler 7 is connected to the other end of the discharge side intermediate pressure mother pipe p23, and the other end of the intermediate cooler 7 is connected to one end of the suction side intermediate pressure mother pipe p24. The intermediate cooler 7 is a heat exchanger that functions as a refrigerant cooler that is discharged from the low-pressure compression elements 31e and 32e that are the compression elements on the front stage side and sucked into the high-pressure compression elements 31d and 32d that are the compression elements on the rear stage. is there. Although not shown here, the intermediate cooler 7 is supplied with water and air as a cooling source for exchanging heat with the refrigerant flowing through the intermediate cooler 7. Thus, the intermediate cooler 7 can be called a cooler using an external heat source in the sense that it does not use the refrigerant circulating in the refrigerant circuit 2.

(1-8) Regulating valve In the regulating valve 8, one of the two compressors 31 and 32 (hereinafter referred to as a stop compressor) stops driving, and the other compressor is driven. In this case, it is a valve for adjusting the communication state between the stop compressor and each of the pipes p1, p2, and p3. Specifically, for example, when the compressor 32 is a stop compressor, the regulating valve 8 is a refrigerant in only one of the high pressure pipe p1, the medium pressure pipe p2, and the low pressure pipe p3 in the stop compressor unit 32. Is allowed to flow between the other pipes p1, p2, and p3.

  Here, in the present embodiment, the case where the stop compressor 32 stops driving in a state where the medium-pressure refrigerant discharged from the low-pressure compression element 32e is filled in the dome 32a will be described. In this case, the regulating valve 8 includes high pressure side check valves 81 and 82, intermediate pressure side check valves 83 and 84, and low pressure side check valves 85 and 86. That is, in this embodiment, when the dome of the stop compressor is filled with the medium-pressure refrigerant and the drive is stopped, three check valves 82, for one compressor 32 (or the compressor 31). 84, 86 (or check valves 81, 83, 85) are provided as the regulating valve 8.

  The high pressure side check valves 81 and 82 are provided on the discharge branch pipes p11b and p12b between the discharge ports of the oil separators 21a and 22a and the high pressure pipe p1. The high pressure side check valves 81 and 82 allow the flow of refrigerant from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high pressure pipe p1, and conversely, from the high pressure pipe p1 to the compressors 31 and 32, in particular. The refrigerant flow toward the discharge port of the stop compressor 32 is blocked.

  The intermediate pressure check valves 83 and 84 are respectively provided on the intermediate pressure pipe p2. More specifically, the intermediate pressure side check valves 83 and 84 are connected between the discharge ports of the oil separators 25a and 26a and the discharge side intermediate pressure mother pipe p23, and the low pressure compression elements 31e and 32e, particularly the stop. The refrigerant flow from the discharge port of the low pressure compression element 32e of the compressor 32 toward the high pressure compression elements 31d and 32d is allowed, and conversely, the low pressure compression elements 31e and 32e from the high pressure compression elements 31d and 32d, particularly the stop compressor. The refrigerant flow toward the discharge port of the 32 low-pressure compression elements 32e is blocked.

  The low pressure side check valves 85 and 86 are provided on the low pressure suction pipes p31a and p32a. The low pressure side check valves 85 and 86 allow only the flow of refrigerant from the low pressure pipe p3 toward the compressors 31 and 32, particularly the stop compressor 32, and conversely, the low pressure side check valves 85 and 86 are low pressure from the compressors 31 and 32, particularly the stop compressor 32. The refrigerant flowing toward the pipe p3 is blocked.

  Generally, when the stop compressor 32 stops driving with the medium pressure refrigerant compressed by the low pressure compression elements 31e and 32e filled in the dome 32a, immediately after the stop compressor 32 stops driving, Depending on the level of pressure in the dome 32a of the compressor 32, a pressure difference may occur between the inside of the dome 32a of the stop compressor 32 and the medium pressure pipe p2 or the high pressure pipe p1. Then, if the intermediate pressure side check valves 83 and 84 and the high pressure side check valves 81 and 82 are not provided as in the prior art, the refrigerant is transferred from the stop compressor 32 to the pipes p1 and p2 side. The accompanying refrigeration oil may leak. In particular, since the high-pressure refrigerant flows into the high-pressure pipe p1, the pressure on the high-pressure pipe p1 side is lower than the inside of the dome 32a. Therefore, the high-pressure side check valves 81 and 82 are not provided. The refrigerant may flow from the high-pressure pipe p1 side into the dome 32a. However, the flow of the refrigerant from the high pressure compression elements 31d and 32d to the low pressure compression elements 31e and 32e through the medium pressure pipe p2 is blocked by the above-described intermediate pressure check valves 83 and 84, and the high pressure check valves 81 and 82 (particularly, the high-pressure check valve 82) blocks the refrigerant flow from the high-pressure pipe p1 toward the stop compressor 32. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes an intermediate pressure when the drive is stopped, the intermediate pressure pipe p2 from the discharge side of the low pressure compression element 32e of the stop compressor 32, and the high pressure pipe p1 side from the discharge side of the high pressure compression element 32d. The refrigerant and the accompanying refrigeration oil do not flow out to the bottom. Therefore, a shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

  In addition, since the low-pressure check valves 85 and 86 described above are provided, the stop compressor 32 stops driving while the medium-pressure refrigerant compressed by the low-pressure compression elements 31e and 32e is filled in the dome 32a. Even if the low-pressure refrigerant flows into the low-pressure pipe p3, the refrigerant flow from the stop compressor 32 toward the low-pressure pipe p3 is blocked. This prevents the refrigerant and the accompanying refrigeration oil from flowing out from the stop compressor 32 to the low-pressure pipe p3 side through the suction port. Therefore, a shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

  In particular, in the stop compressor 32 in which the inside of the dome 32a is in an intermediate pressure state when the drive is stopped, the regulating valve 8 can be configured by only the check valves 81 to 86. Therefore, the flow of the refrigerant can be adjusted with a simple configuration, and the cost can be reduced as compared with the case where the adjustment valve 8 is configured by an electromagnetic valve or the like.

  In addition, when the priority of operation is provided between the compressors 31 and 32 (for example, when the compressor 31 is a compressor that operates preferentially), the stop compressor is limited to the compressor 32. It will be. In such a case, the check valves 81, 83, 85 corresponding to the compressor 31 may not be provided, and only the check valves 82, 84, 86 corresponding to the stop compressor 32 may be provided.

  Furthermore, although not shown here, the air conditioner 1 has a control unit that controls the operation of each part of the air conditioner 1 such as the compression mechanism 2 and the expansion mechanism 5.

(2) Operation Next, the operation of the air conditioner 1 of the present embodiment will be described with reference to FIGS. 2 is a pressure-enthalpy diagram illustrating the refrigeration cycle during the cooling operation, and FIG. 3 is a temperature-entropy diagram illustrating the refrigeration cycle during the cooling operation. In addition, the operation control in the following cooling operation is performed by the above-described control unit (not shown). In the following description, “high pressure” means high pressure in the refrigeration cycle (that is, pressure at points D, D ′, and E in FIGS. 2 and 3), and “low pressure” means low pressure in the refrigeration cycle. (That is, pressure at points A and F in FIGS. 2 and 3), and “intermediate pressure” means intermediate pressure in the refrigeration cycle (that is, pressure at points B and C in FIGS. 2 and 3). is doing.

-Cooling operation-
During the cooling operation, the opening degree of the expansion mechanism 5 is adjusted. In the state of the refrigerant circuit 2, low-pressure refrigerant (see point A in FIGS. 1 to 3) is sucked into the compressors 31 and 32 of the compression mechanism 3 from the low-pressure pipe p3 and the low-pressure suction pipes p31a and p32a. . The low-pressure refrigerant is first compressed to an intermediate pressure by the low-pressure compression elements 31e and 32e, and then discharged to the intermediate-pressure pipe p2 (see point B in FIGS. 1 to 3). Then, the medium pressure refrigerant discharged from the compressors 31 and 32 to the medium pressure pipe p2 flows into the oil separators 25a and 26a constituting the oil separation mechanisms 25 and 26, respectively, and the refrigerating machine oil in the refrigerant is supplied. To be separated. In addition, the refrigeration oil separated from the medium pressure refrigerant in the oil separators 25a and 26a flows into the oil return pipes 25c and 26c constituting the oil separation mechanisms 25 and 26, and is decompressed by the decompression mechanisms 25b and 26b. After that, the refrigerant is returned to the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2 and again sucked into the high pressure compression elements 31d and 32d which are internal discharge compression elements of the compressors 31 and 32, respectively.

  The intermediate-pressure refrigerant discharged from the low-pressure compression elements 31e and 32e as the previous stage is cooled by exchanging heat with water or air as a cooling source in the intermediate cooler 7 (FIGS. 1 to 3). (See point C). The refrigerant cooled in the intermediate cooler 7 is then sucked into the high-pressure compression elements 31d and 32d, which are the subsequent stages of the low-pressure compression elements 31e and 32e, and further compressed, and is discharged from the compressors 31 and 32 at a high pressure. It discharges to each of pipe | tube p11a, p12a (refer the point D of FIGS. 1-3). Here, the high-pressure refrigerant discharged from the compressors 31 and 32 is subjected to the critical pressure (that is, at the critical point CP shown in FIG. 2) by the two-stage compression operation by the four compression elements 31e, 32e, 31d, and 32d. The pressure is compressed to a pressure exceeding the critical pressure Pcp). The high-pressure refrigerant flows into the oil separators 21a and 22a constituting the oil separation mechanisms 21 and 22, and the refrigerating machine oil in the refrigerant is separated. In addition, the refrigerating machine oil separated from the high-pressure refrigerant in the oil separators 21a and 22a flows into the oil return pipes 21c and 22c constituting the oil separation mechanisms 21 and 22, respectively, and is decompressed by the decompression mechanisms 21b and 22b. Then, the refrigerant is returned to the suction side intermediate pressure branch pipes p26 and p25 of the intermediate pressure pipe p2 and again sucked into the high pressure compression elements 31d and 32d which are internal discharge compression elements of the compressors 31 and 32, respectively.

  Next, the high-pressure refrigerant after the refrigerating machine oil is separated in the oil separation mechanisms 21 and 22 is sent to the heat source side heat exchanger 4 functioning as a refrigerant radiator through the discharge branch pipes p11b and p12b and the high-pressure pipe p1. It is done. The high-pressure refrigerant sent to the heat source side heat exchanger 4 is cooled by exchanging heat with water or air as a cooling source in the heat source side heat exchanger 4 (see point E in FIGS. 1 to 3). . The high-pressure refrigerant cooled in the heat source-side heat exchanger 4 is decompressed by the expansion mechanism 5 to become a low-pressure gas-liquid two-phase refrigerant, and is sent to the use-side heat exchanger 6 that functions as a refrigerant evaporator ( (See point F in FIGS. 1 to 3). The low-pressure gas-liquid two-phase refrigerant sent to the use side heat exchanger 6 is heated and evaporated in the use side heat exchanger 6 by exchanging heat with water or air as a heating source. (Refer to point A in FIGS. 1 to 3). Then, the low-pressure refrigerant heated in the use side heat exchanger 6 is again sucked from the low-pressure suction ports of the compressors 31 and 32. In this way, the cooling operation is performed.

  As described above, in the air conditioner 1, the intermediate cooler 7 is provided in the intermediate pressure pipe p2 for sucking the refrigerant discharged from the low pressure compression elements 31e and 32e into the high pressure compression elements 31d and 32d. Thus, the intermediate cooler 7 is in a state of functioning as a cooler. Therefore, compared with the case where the intercooler 7 is not provided (in this case, the refrigeration cycle is performed in the order of point A → point B → point D ′ → point E → point F in FIGS. 2 and 3). Thus, the temperature of the refrigerant sucked into the high-pressure compression elements 31d and 32d, which are the subsequent stages of the low-pressure compression elements 31e and 32e, decreases (see points B and C in FIG. 3), and the refrigerant discharged from the high-pressure compression elements 31d and 32d. (See points D and D ′ in FIG. 3). For this reason, in this air conditioning apparatus 1, compared with the case where the intermediate cooler 7 is not provided in the heat-source-side heat exchanger 4 that functions as a high-pressure refrigerant radiator, The temperature difference can be reduced and the heat dissipation loss can be reduced, so that the operation efficiency can be improved.

(3) Features (3-1)
According to the air conditioner 1, in the state where one of the two compressors 31 and 32 (for example, the compressor 32) has stopped driving and the other compressor 31 is driving. The refrigerant flows between the compressor 32 whose driving is stopped by the regulating valve 8 and any one of the pipes (specifically, the high-pressure pipe p1, the medium-pressure pipe p2, and the low-pressure pipe p3). The flow of refrigerant does not occur with this pipe. In the present embodiment, the refrigerant flows only between the suction side of the high pressure compression element 32d in the stop compressor 32 and the intermediate pressure pipe p2, and the high pressure pipe p1 and the low pressure pipe p3 and the stop compressor 32 are connected. The refrigerant is prevented from flowing between them. Thereby, the inside of the dome 32a of the stop compressor 32 is equalized, and the pressure difference of the refrigerant on the intermediate pressure pipe p2 is eliminated. Therefore, the refrigerant and the accompanying flow of the refrigeration oil due to the pressure difference do not occur.

(3-2)
The stop compressor 32 is composed of one compressor in which the high pressure compression element 32d and the low pressure compression element 32e are accommodated in one dome 32a. Therefore, the flow of the refrigerant from the stop compressor 32 to the other compressor 31 is not generated, and the inside of the dome 32a can be equalized.

(3-3)
In general, when the stop compressor stops driving in a state where the medium pressure refrigerant compressed by the low pressure compression element is filled in the dome, the low pressure refrigerant flows into the low pressure pipe side. Due to the pressure difference between the inside of the dome of the stop compressor and the inside of the low pressure pipe, the refrigeration oil flows from the inside of the stop compressor, which is in an intermediate pressure state, to the low pressure pipe side where the pressure is lower than the inside of the compressor through the suction port There is a risk of leaking.

  However, in the present embodiment, by providing the low pressure side check valves 85 and 86 (particularly, the low pressure side check valve 86), the flow of the refrigerant from the stop compressor 32 toward the low pressure pipe p3 side is blocked. Therefore, the refrigeration oil does not flow out from the stop compressor 32 to the low-pressure pipe p3 side through the suction port. Therefore, a shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

(3-4)
In general, when the stop compressor stops driving with the medium-pressure refrigerant compressed by the low-pressure compression element filled in the dome, immediately after the stop compressor stops driving, Depending on the level of pressure in the dome, a pressure difference is generated between the dome of the stop compressor and the medium-pressure pipe and / or the high-pressure pipe, and the refrigerant and the accompanying refrigeration are transferred from the stop compressor 32 to these pipes. There is a risk of machine oil leaking. In particular, since a high-pressure refrigerant flows into the high-pressure pipe, the pressure on the high-pressure pipe side is lower than that inside the dome, so that the refrigerant and the accompanying refrigeration oil flow from the high-pressure pipe side into the dome. There is a fear.

  However, in the present embodiment, the intermediate pressure side check valves 83 and 84 (particularly, the intermediate pressure side check valve 84) cause the high pressure compression element 32d of the stop compressor 32 to the low pressure compression element 32d via the intermediate pressure pipe p2. The flow of the refrigerant that is directed is interrupted on the discharge side of the low-pressure compression element 32e, and the high-pressure check valves 81 and 82 (particularly, the high-pressure check valve 82) cause the refrigerant flowing from the high-pressure pipe p1 to the stop compressor 32 side. The flow is interrupted. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes an intermediate pressure when the drive is stopped, from the low pressure discharge side of the stop compressor 32 (that is, the discharge side of the low pressure compression element 32e) to the intermediate pressure pipe p2 and the high pressure discharge side (that is, Refrigerator oil does not flow out from the discharge side of the compressor 32 to the high-pressure pipe p1 side. Therefore, a shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

  In particular, in the stop compressor 32 in which the inside of the dome 32a is in an intermediate pressure state when the drive is stopped, the adjustment valve 8 can be configured with only a check valve. Therefore, the flow of the refrigerant can be adjusted with a simple configuration, and the cost can be reduced as compared with the case where the adjustment valve 8 is configured with an electromagnetic valve or the like.

(4) Modification (4-1) Modification A
In the above-described embodiment, the compressors 31 and 32 at the time of driving are high-pressure dome type compressors, and the stop compressor (hereinafter, the stop compressor is described as the compressor 32) is located inside the dome 32a. The case where driving is stopped in the state of pressure has been described. However, the stop compressor 32 may stop driving when the inside of the dome 32a is not at a medium pressure but at a high pressure.

  FIG. 4 is a schematic configuration diagram of an air conditioner 1A according to Modification A. The air conditioner 1A is different from the air conditioner 1 of FIG. In the air conditioner 1 </ b> A, the dome 32 a of the stop-stop compressor 32 that has stopped driving is filled with the high-pressure refrigerant discharged from the high-pressure compression element 32 d of the compressor 32. The regulating valve 8A according to the air conditioner 1A includes medium pressure discharge side stop valves (corresponding to a close valve) 83A and 84A, low pressure side check valves 85A and 86A, and medium pressure suction side check valves 87A and 88A. Composed.

  The intermediate pressure discharge side stop valves 83A and 84A are respectively provided on the intermediate pressure pipe p2. More specifically, the intermediate pressure discharge side stop valves 83A and 84A are connected between the discharge ports of the oil separators 25a and 26a and the discharge side intermediate pressure mother pipe p23, and are constituted by electromagnetic valves. . The intermediate pressure discharge side stop valves 83A and 84A are in an “open” state when the compressors 31 and 32 are driven, and when the corresponding compressors 31 and 32 are stopped. , “Closed” state. For example, if the stop compressor is the compressor 32, medium pressure refrigerant flows from the low pressure compression element 32e to the high pressure compression element 32d in the intermediate pressure pipe p2 when the stop compressor 32 is driven. Become. However, when the drive of the stop compressor 32 is stopped, the inside of the dome 32a is kept in a high pressure state. On the other hand, immediately after the drive is stopped, the discharge side intermediate pressure branch pipe p22 on the stop compressor 32 side of the intermediate pressure pipe p2 is placed. Means that medium-pressure refrigerant flows in. Then, the refrigerant flows out from the high-pressure dome 32a to the low-pressure intermediate pressure pipe p2, and the flow direction of the refrigerant is the same as when the compressor 32 is driven. Therefore, in the modified example A, due to the pressure relationship of the refrigerant, the medium pressure pipe p2 in which the direction in which the refrigerant flows out when the stop compressor 32 is stopped is the same as when the stop compressor 32 is driven, In particular, on the discharge side of the stop compressor 32, medium pressure discharge side stop valves 83A and 84A that are electromagnetic valves are provided instead of check valves. Thereby, when the stop compressor 32 stops driving, it is possible to reliably prevent the refrigerant from flowing out.

  The control of the opening / closing operation of the intermediate pressure discharge side stop valves 83A, 84A is performed by a control unit (not shown).

  The low-pressure check valves 85A and 86A are the same as the low-pressure check valves 85 and 86 of the air conditioner 1 according to FIG. That is, the low pressure side check valves 85 and 86 are provided on the low pressure suction pipes p31a and p32a, respectively, and allow only the flow of refrigerant from the low pressure pipe p3 toward the compressors 31 and 32 (particularly the stop compressor 32). On the contrary, the refrigerant flow from the stop compressor 32 toward the low pressure pipe p3 is blocked. As a result, the refrigeration oil does not flow out from the stop compressor 32 to the low-pressure pipe p3 via the suction port, so that the shortage of the refrigeration oil when starting the stop compressor 32 is less likely to occur. .

  The intermediate pressure suction side check valves 87A and 88A are provided in the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2. More specifically, the intermediate pressure suction side check valves 87A and 88A are connected to the connection points of the oil return pipes 21c and 22c and the suction side intermediate pressure branch pipes p25 and p26 in the oil separation mechanisms 21 and 22, respectively. The separation mechanisms 25 and 26 are connected between the oil return pipes 25c and 26c and the connection points of the suction side intermediate pressure branch pipes p25 and p26. The medium pressure suction side check valves 87A and 88A allow the flow of refrigerant from the suction side medium pressure mother pipe p24 to the compressors 31 and 32, particularly the suction port of the high pressure compression element 32d of the stop compressor 32, and conversely. The refrigerant flows from the compressors 31 and 32, particularly the suction port of the high-pressure compression element 32d, toward the suction-side intermediate pressure mother pipe p24.

  As described above, when the compressor 31 is driven and the stop compressor 32 is stopped, the inside of the dome 32a of the stop compressor 32 is in a high pressure state, and the medium-pressure refrigerant discharged from the compressor 31 is medium. Since the pressure pipe p2 flows, a pressure difference is generated between the dome 32a and the intermediate pressure pipe p2. However, the medium pressure suction side check valves 87A and 88A described above can prevent the refrigerant and the accompanying refrigeration oil from flowing out from the suction side of the high pressure compression element 32e of the compressor 32 to the medium pressure pipe p2. Therefore, the inside of the dome 32a of the stop compressor 32 can be equalized.

(4-2) Modification B
In the above-described embodiment and modification A, the compressors 31 and 32 at the time of driving are high-pressure dome type compressors, and the stop compressor 32 stops driving when the inside of the dome 32a is at an intermediate pressure or high pressure. Explained when to do. However, the stop compressor 32 may stop driving while the inside of the dome 32a is in a low pressure state.

  FIG. 5 is a schematic configuration diagram of an air-conditioning apparatus 1B according to Modification B. The air conditioner 1B is different from the air conditioner 1 of FIG. Further, when the compressor 31 according to the air conditioner 1B is driven and the stop compressor 32 stops driving, the inside of the dome 32a of the stop compressor 32 is a low-pressure refrigerant sucked from the low-pressure pipe p3 side. It becomes a full state. The regulating valve 8B related to the air conditioner 1B includes high pressure side check valves 81B and 82B, medium pressure discharge side check valves 83B and 84B, and medium pressure suction side stop valves (corresponding to close valves) 87B and 88B. Composed.

  The high pressure side check valves 81B and 82B are different from the high pressure side check valves 81 and 82 in FIG. The high pressure side check valves 81B and 82B are connected to the high pressure discharge pipes p11a and p12a, that is, between the discharge ports of the compressors 31 and 32 and the suction ports of the oil separators 21a and 22a, respectively. The high pressure side check valves 81B and 82B allow the flow of refrigerant from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high pressure pipe p1, and conversely from the high pressure pipe p1 to the compressors 31 and 32, in particular. The refrigerant flow toward the discharge port of the stop compressor 32 is blocked. In particular, the high-pressure check valve 82B stops the flow before the refrigerant from the outlet of the stopped compressor 32 that has stopped flows into the oil separation mechanism 22. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes a low pressure when the drive is stopped, the refrigerant and the accompanying refrigeration oil do not flow out from the high pressure pipe p1 side to the high pressure discharge side of the stop compressor 32. Insufficient refrigerator oil when starting the stop compressor 32 is less likely to occur.

  The medium pressure discharge side check valves 83B and 84B are connected between the discharge ports of the oil separators 25a and 26a and the discharge side intermediate pressure mother pipe p23, respectively, similarly to the medium pressure side check valves 83 and 84 in FIG. The refrigerant flows from the discharge ports of the low pressure compression elements 31e and 32e toward the high pressure compression elements 31d and 32d, and conversely from the high pressure compression elements 31d and 32d to the discharge ports of the low pressure compression elements 31e and 32e. Block the flow of refrigerant going. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes a low pressure when the drive is stopped, the refrigerant and the refrigeration associated therewith are transferred from the low pressure discharge side of the stop compressor 32 to the intermediate pressure pipe p2 into which the medium pressure refrigerant flows. Since the machine oil does not flow out, a shortage of refrigeration oil when starting the stop compressor 32 is less likely to occur.

  The intermediate pressure suction side closing valves 87B and 88B are provided in the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2. More specifically, the intermediate pressure suction side stop valves 87B and 88B are connected to the connection points of the oil return pipes 21c and 22c and the suction side intermediate pressure branch pipes p26 and p25 in the oil separation mechanisms 21 and 22, respectively, The separation mechanisms 25 and 26 are connected between the oil return pipes 25c and 26c and the connection points of the suction side intermediate pressure branch pipes p25 and p26. The intermediate pressure suction side closing valves 87B and 87B are composed of solenoid valves, and when the compressors 31 and 32 are driven, they are in an “open” state, and the corresponding compressors 31 and 32 stop driving. If it is, it will be in the “closed” state. This means that when the stop compressor 32 is driven, medium pressure refrigerant flows through the intermediate pressure pipe p2 from the low pressure compression element 32e to the high pressure compression element 32d. However, when the drive of the stop compressor 32 is stopped, the inside of the dome 32a is kept in a low pressure state. On the other hand, immediately after the drive is stopped, the medium pressure refrigerant flows into the intermediate pressure pipe p2. Then, the refrigerant flows out from the high pressure medium pressure pipe p2 into the low pressure dome 32a, and the flow direction of the refrigerant is the same as when the compressor 32 is driven. Therefore, in the modified example B, due to the pressure relationship of the refrigerant, the medium pressure pipe p2 in which the direction in which the refrigerant flows out when the stop compressor 32 is stopped is the same as that when the stop compressor 32 is driven, In particular, on the suction side of the stop compressor 32, medium pressure suction side closing valves 87B and 88B which are electromagnetic valves instead of check valves are provided. Thereby, when a stop compressor stops a drive, the outflow of a refrigerant | coolant can be prevented reliably.

  Note that the control of the opening / closing operation of the intermediate pressure suction side stop valves 87B, 88B is performed by a control unit (not shown).

(4-3) Modification C
In the above-described embodiment, the case where the compressors 31 and 32 at the time of driving are high-pressure dome type compressors has been described. However, the compressors 31 and 32 are medium-pressure dome type compressors that are filled with the medium-pressure refrigerant discharged from the low-pressure compression elements 31e and 32e instead of the high-pressure compression elements 31d and 32d when driven. Also good. Here, when the compressor 31 is driven and the stop compressor 32 stops driving, the medium-pressure refrigerant discharged from the low-pressure compression elements 31e and 32e is inside the dome 32a of the stop compressor 32. Take the case of fullness as an example.

  FIG. 6 is a schematic configuration diagram of an air-conditioning apparatus 1C according to Modification C. The air conditioner 1C differs from the air conditioner 1 in FIG. 1 in the connection destinations of the oil return pipes 21c, 22c, 25c, and 26c in the oil separation mechanisms 21, 22, 25, and 26, and in the compressors 31 and 32. The discharge pipes p11a, p12a, p21, and p22 in FIG.

  In the compressors 31 and 32 according to the air conditioner 1C, the refrigerant discharged from the low-pressure compression elements 31e and 32e is once discharged into the domes 31a and 32a. That is, the low-pressure compression elements 31e and 32e can be said to be internal discharge compression elements. The refrigerant discharged into the domes 31a and 32a is discharged out of the compressors 31 and 32 from the discharge-side intermediate pressure branch pipes p21 and p22 directly connected to the domes 31a and 32a. On the other hand, the refrigerant discharged from each of the high-pressure compression elements 31d and 32d is discharged outside the respective domes 31a and 32a from the high-pressure discharge pipes p11a and p12a directly connected to the compression elements 31d and 32d. That is, the high pressure compression elements 31d and 32 can be said to be external discharge compression elements.

  The oil return pipe 21c has one end connected to the oil separator 21a and the other end connected to a low pressure suction pipe p31a branched from the low pressure pipe p3. One end of the oil return pipe 22c is connected to the oil separator 22a, and the other end is connected to a low pressure suction pipe p32a branched from the low pressure pipe p3. That is, each of the oil return pipes 21c and 22c is a compressor having high-pressure compression elements 31d and 32d, which are refrigerant sources from which the refrigerating machine oil accompanied by the refrigerating machine oil is separated by the oil separators 21a and 22a. It returns to the suction side of the machines 31 and 32 itself (that is, the suction side of the low pressure compression elements 31e and 32e which are internal discharge compression elements).

  The oil return pipe 25c has one end connected to the oil separator 25a and the other end connected to a low pressure suction pipe p32a branched from the low pressure pipe p3. The oil return pipe 26c has one end connected to the oil separator 26a and the other end connected to a low pressure suction pipe p31a branched from the low pressure pipe p3. In other words, the oil return pipe 25c is not a compressor 31 having a low-pressure compression element 31e, which is a flow source of refrigerant accompanied by the refrigerating machine oil, separated from the refrigerating machine oil separated by the oil separator 25a. The low pressure compression element 32e of 32 (that is, the internal discharge compression element of the compressor 32) is returned to the suction side. Similarly, the oil return pipe 26c is not a compressor 32 having a low-pressure compression element 32e from which the refrigerant oil separated by the oil separator 26a is flowing out of the refrigerant accompanied by the refrigerator oil. It returns to the suction side of the low-pressure compression element 31e of the compressor 31 (that is, the internal discharge compression element of the compressor 31). That is, the oil return pipes 25c and 26c and the low pressure suction pipes p31a and p32a branched from the low pressure pipe p3 are connected in a so-called staking state.

  As a result, the intermediate pressure discharged from the low pressure compression element 31e due to the bias generated between the amount of refrigeration oil accumulated in the low pressure compression element 31e and the amount of refrigeration oil accumulated in the low pressure compression element 32e. Even if there is a bias between the amount of refrigeration oil in the refrigerant and the amount of refrigeration oil in the medium-pressure refrigerant discharged from the low-pressure compression element 32e, the refrigeration of the low-pressure compression elements 31e and 32e A large amount of refrigeration oil returns to a direction where the amount of machine oil is smaller, so that the bias in the amount of refrigeration oil accumulated in the low-pressure compression elements 31e and 32e is eliminated.

  The adjustment valve 8C includes high-pressure check valves 81C and 82C, intermediate-pressure check valves 83C and 84C, and low-pressure check valves 85C and 86C. The low-pressure check valves 85C and 86C are provided on the low-pressure suction pipes p31a and p32a as in FIG. 1, but in the modified example C, the low-pressure check valve 85C includes the oil return pipe 26c and the low-pressure suction pipe. The connection point between the pipe p31a and the connection point between the oil return pipe 21c and the low pressure suction pipe p31a is connected. The low pressure side check valve 86C is connected between a connection point between the oil return pipe 25c and the low pressure suction pipe p32a and a connection point between the oil return pipe 22c and the low pressure suction pipe p32a. The low pressure side check valves 85C and 86C allow only the refrigerant flow from the low pressure pipe p3 to the compressors 31 and 32, particularly the stop compressor 32, and conversely the compressors 31 and 32, particularly the stop, as in FIG. The flow of the refrigerant from the compressor 32 toward the low pressure pipe p3 is blocked. Therefore, when the stop compressor 32 is stopped, the refrigerant and the accompanying refrigeration oil from the low-pressure inlet of the stop compressor 32 where the pressure in the dome 32a is medium pressure to the low-pressure pipe p3 side where the pressure is low. Can be prevented from flowing out.

  Further, as in FIG. 1, the high pressure side check valves 81C and 82C are respectively connected between the discharge ports of the oil separators 21a and 22a and the high pressure pipe p1. The high pressure side check valves 81C and 82C allow the flow of refrigerant from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high pressure pipe p1, and conversely from the high pressure pipe p1 to the compressors 31 and 32, in particular. The refrigerant flow toward the discharge port of the stop compressor 32 is blocked. Therefore, when the compressor 32 is stopped, the refrigerant and the accompanying refrigeration oil flow from the high pressure pipe p1 side where the pressure is high to the high pressure discharge port of the stop compressor 32 where the pressure in the dome 32a is medium pressure. It can be prevented from flowing out.

  Further, similarly to FIG. 1, the intermediate pressure side check valves 83C and 84C are respectively provided on the intermediate pressure pipe p2. The intermediate pressure check valves 83C and 84C allow the refrigerant to flow from the discharge ports of the low pressure compression elements 31e and 32e, particularly the stop compressor 32, to the high pressure compression elements 31d and 32d, and conversely, the high pressure compression elements 31d. , 32d from the low-pressure compression elements 31e, 32e, in particular, the refrigerant flow toward the discharge port of the stop compressor 32 is blocked.

(4-4) Modification D
Here, similarly to the above-described modified example C, the compressors 31 and 32 at the time of driving are of the medium pressure dome type, and the stop compressor 32 is described in the case where the driving is stopped while the inside of the dome 32a is at a high pressure. To do.

  FIG. 7 is a schematic configuration diagram of an air-conditioning apparatus 1D according to Modification D. The air conditioner 1D is different from the air conditioner 1C according to the modified example C in the types and positions of the regulating valves 8D. Further, when the compressor 31 related to the air conditioner 1D is driven and the compressor 32 stops driving, the dome 32a of the stopped compressor 32 has a high pressure discharged from the high-pressure compression element 32d of the compressor 32. It will be in the state filled with the refrigerant. The regulating valve 8D related to the air conditioner 1D includes medium pressure discharge side stop valves (corresponding to a close valve) 83D and 84D, low pressure side check valves 85D and 86D, and medium pressure suction side check valves 87D and 88D. Composed.

  The intermediate pressure discharge side stop valves 83D and 84D are respectively provided on the discharge side intermediate pressure branch pipes p21 and p22 of the intermediate pressure pipe p2, and are constituted by electromagnetic valves. That is, the intermediate pressure discharge side stop valves 83D and 84D are provided on the pipes p21 and p22 through which the medium pressure refrigerant flows before the refrigerating machine oil is separated by the oil separation mechanisms 25 and 26, respectively. The intermediate pressure discharge side stop valves 83D and 84D are in an “open” state when the compressors 31 and 32 are driven, and when the corresponding compressors 31 and 32 are stopped. , “Closed” state. This means that when the stop compressor 32 is driven, medium pressure refrigerant flows through the intermediate pressure pipe p2 from the low pressure compression element 32e to the high pressure compression element 32d. However, when the drive of the stop compressor 32 is stopped, the inside of the dome 32a is maintained in a high pressure state. On the other hand, immediately after the drive is stopped, the discharge side intermediate pressure branch pipe p22 on the stop compressor 32 side of the intermediate pressure pipe p2 is placed. The medium-pressure refrigerant flows in. Then, the refrigerant flows out from the high-pressure dome 32a to the low-pressure intermediate pressure pipe p2, and the flow direction of the refrigerant is the same as when the compressor 32 is driven. Therefore, in Modification D, due to the pressure relationship of the refrigerant, in the intermediate pressure pipe p2 in which the direction in which the refrigerant flows out when the stop compressor 32 is stopped is the same as when the stop compressor 32 is driven, In particular, on the intermediate pressure discharge side of the stop compressor 32, medium pressure discharge side stop valves 83D and 84D that are electromagnetic valves are provided instead of check valves. Thereby, when the stop compressor 32 stops driving, it is possible to reliably prevent the refrigerant from flowing out.

  In addition, control of the opening / closing operation | movement of the intermediate pressure discharge side stop valve 83D and 84D is performed by the control part which is not shown in figure.

  The low pressure side check valves 85D and 86D and the intermediate pressure suction side check valves 87D and 88D are the same as the air conditioner 1A according to the modified example A shown in FIG. That is, the low pressure side check valves 85D and 86D are provided on the low pressure suction pipes p31a and p32a, respectively. Further, as in FIG. 6 of Modification C, the low pressure side check valve 85D is connected between the connection point of the oil return pipe 26c and the low pressure suction pipe p31a and the connection point of the oil return pipe 21c and the low pressure suction pipe p31a. Has been. The low pressure side check valve 86D is connected between a connection point between the oil return pipe 25c and the low pressure suction pipe p32a and a connection point between the oil return pipe 22c and the low pressure suction pipe p32a. The low pressure side check valves 85D and 86D allow only the flow of refrigerant from the low pressure pipe p3 toward the compressors 31 and 32, particularly the stop compressor 32, and conversely the low pressures from the compressors 31 and 32, particularly the stop compressor 32. The refrigerant flowing toward the pipe p3 is blocked. This prevents the refrigerant and the accompanying refrigeration oil from flowing out from the stop compressor 32 to the low-pressure pipe p3 via the low-pressure intake port, so that there is a shortage of refrigeration oil when starting the stop compressor 32. Is less likely to occur. Further, the intermediate pressure suction side check valves 87D and 88D are provided in the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2, and the compressors 31 and 32, in particular, from the suction side intermediate pressure mother pipe p24. The refrigerant flow toward the suction port of the high-pressure compression element 32d of the stop compressor 32 is allowed, and conversely, the refrigerant flow toward the suction-side intermediate-pressure mother pipe p24 from the suction ports of the compressors 31, 32, particularly the high-pressure compression element 32d. Shut off. As a result, the refrigeration oil does not flow out from the stop compressor 32 to the intermediate pressure pipe p <b> 2 through the suction port, so that the shortage of refrigeration oil when starting the stop compressor 32 is less likely to occur. Yes.

(4-5) Modification E
Here, similarly to the above-described modification C, the compressors 31 and 32 at the time of driving are of the medium pressure dome type, and the stop compressor 32 is described as a case where the driving is stopped while the inside of the dome 32a is in a low pressure state. To do.

  FIG. 8 is a schematic configuration diagram of an air-conditioning apparatus 1E according to Modification E. The air conditioner 1E is different from the air conditioner 1C according to the modified example C in the types and positions of the regulating valves 8E. Further, when the compressor 31 related to the air conditioner 1E is driven and the compressor 32 stops driving, the dome 32a of the stop compressor 32 is filled with the low-pressure refrigerant sucked from the low-pressure pipe p3 side. It becomes a state. The regulating valve 8E related to the air conditioner 1E includes high pressure side check valves 81E and 82E, medium pressure discharge side check valves 83E and 84E, and medium pressure suction side stop valves (corresponding to close valves) 87E and 88E. Composed.

  The high pressure side check valves 81E and 82E are connected to the discharge branch pipes p11b and p12b, that is, between the discharge ports of the oil separators 21a and 22a and the high pressure pipe p1, respectively. The high pressure side check valves 81E and 82E allow the flow of refrigerant from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high pressure pipe p1, and conversely from the high pressure pipe p1 to the compressors 31 and 32, in particular. The refrigerant flow toward the discharge port of the stop compressor 32 is blocked. In particular, the high pressure side check valves 81E and 82E stop the flow of the refrigerant after the refrigeration oil is separated in the oil separation mechanisms 21 and 22. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes a low pressure when the drive is stopped, the refrigerant and the accompanying refrigeration oil do not flow out from the high pressure pipe p1 side to the high pressure discharge of the stop compressor 32. A shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

  The intermediate pressure discharge side check valves 83E and 84E and the intermediate pressure suction side stop valves 87E and 88E are the same as the air conditioner 1B according to the modified example B shown in FIG. That is, the intermediate pressure discharge side check valves 83E, 84E are connected between the discharge ports of the oil separators 25a, 26a and the discharge side intermediate pressure mother pipe p23, and the low pressure compression elements 31e of the compressors 31, 32 are connected. , 32e is allowed to flow toward the high-pressure compression elements 31d, 32d, and conversely, the refrigerant flow from the high-pressure compression elements 31d, 32d to the low-pressure compression elements 31e, 32e is blocked. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes a low pressure when the drive is stopped, the refrigeration oil flows out from the intermediate pressure pipe p2 side to the discharge side of the low pressure compression elements 31e and 32e of the stop compressor 32. Therefore, the shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

  Further, the intermediate pressure suction side stop valves 87E and 88E are provided in the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2, and are constituted by electromagnetic valves. The intermediate pressure suction side closing valves 87E and 88E are in an “open” state when the compressors 31 and 32 are driven, and when the corresponding compressors 31 and 32 are stopped. , “Closed” state. Thereby, when the stop compressor 32 stops driving, it is possible to reliably prevent the refrigerant and the accompanying refrigeration oil from flowing out. Note that the control of the opening / closing operation of the intermediate pressure suction side closing valves 87E, 88E is performed by a control unit (not shown).

(4-6) Modification F
Here, the case where each compressor 31 and 32 at the time of a drive is a low pressure dome type compressor with which the low voltage | pressure refrigerant | coolant suck | inhaled from the low voltage | pressure piping p3 fills in the dome 31a, 32a is demonstrated. Here, when the compressor 31 is driven and the stop compressor 32 stops driving, the stop compressor 32 is a medium-pressure refrigerant discharged from the low-pressure compression elements 31e and 32e. Take the case of fullness as an example.

  FIG. 9 is a schematic configuration diagram of an air-conditioning apparatus 1F according to Modification F. The air conditioner 1F differs from the air conditioner 1 of FIG. 1 in the connection destinations of the oil return pipes 21c, 22c, 25c, and 26c in the oil separation mechanisms 21, 22, 25, and 26.

  In the compressors 31 and 32 according to the air conditioner 1F, the low-pressure refrigerant sucked into the domes 31a and 32a of the compressors 31 and 32 through the low-pressure pipes p3 and the low-pressure suction pipes p31a and p32a is temporarily It discharges to each dome 31a, 32a. The refrigerant is compressed by the low-pressure compression elements 31e and 32e, further compressed by the high-pressure compression elements 31d and 32d, and then discharged to the outside of the compressors 31 and 32.

  The oil return pipe 21c has one end connected to the oil separator 21a and the other end connected to a low pressure suction pipe p31a branched from the low pressure pipe p3. One end of the oil return pipe 22c is connected to the oil separator 22a, and the other end is connected to a low pressure suction pipe p32a branched from the low pressure pipe p3. One end of the oil return pipe 25c is connected to the oil separator 25a, and the other end is connected to a low pressure suction pipe p31a branched from the low pressure pipe p3. One end of the oil return pipe 26c is connected to the oil separator 26a, and the other end is connected to the low pressure suction pipe p32a branched from the low pressure pipe p3. That is, each of the oil return pipes 21c, 22c, 25c, and 26c is not in the state of being brushed, but the refrigerating machine oil is accompanied by the refrigerating machine oil separated by each of the oil separators 21a, 22a, 25a, and 26a. The refrigerant is returned to the low pressure inlet side of the compressors 31 and 32 themselves.

  The adjustment valve 8F includes high-pressure check valves 81F and 82F, intermediate-pressure check valves 83F and 84F, and low-pressure check valves 85F and 86F. The high pressure side check valves 81F and 82F, the intermediate pressure side check valves 83F and 84F, and the low pressure side check valves 85F and 86F are the same as the air conditioner 1 of FIG. That is, the high pressure side check valves 81F and 82F are respectively connected between the discharge ports of the oil separators 21a and 22a and the high pressure pipe p1. The high pressure side check valves 81F and 82F allow the refrigerant to flow from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high pressure pipe p1, and conversely, from the high pressure pipe p1 to the compressors 31 and 32, in particular. The refrigerant flow toward the discharge port of the stop compressor 32 is blocked. Therefore, when the compressor 32 is stopped, it is possible to prevent the refrigerant from flowing out from the high pressure pipe p1 side where the pressure is high to the high pressure discharge port of the stop compressor 32 where the inside of the dome 32a is medium pressure. it can. The intermediate pressure check valves 83F and 84F are provided on the intermediate pressure pipe p2, respectively, and allow the refrigerant to flow from the discharge ports of the low pressure compression elements 31e and 32e toward the high pressure compression elements 31d and 32d. In addition, the flow of the refrigerant from the high pressure compression elements 31d and 32d toward the discharge ports of the low pressure compression elements 31e and 32e is blocked. The low-pressure side check valves 85F and 86F are provided on the low-pressure suction pipes p31a and p32a, respectively, and allow only the flow of refrigerant from the low-pressure pipe p3 toward the compressors 31 and 32, particularly the stop compressor 32. In addition, the flow of refrigerant from the compressors 31 and 32, particularly the stop compressor 32, to the low pressure pipe p3 is blocked. Therefore, when the stop compressor 32 is stopped, it is possible to prevent the refrigerant and the accompanying refrigeration oil from flowing out from the high pressure discharge port side in the dome 32a to the low pressure pipe p3 side where the pressure is low. .

(4-7) Modification G
Here, similarly to the above-described modification F, the case where the compressors 31 and 32 at the time of driving are low-pressure dome type and the stop compressor 32 stops driving while the inside of the dome 32a is in a high pressure state will be described. .

  FIG. 10 is a schematic configuration diagram of an air-conditioning apparatus 1G according to Modification G. The air conditioner 1G is different from the air conditioner 1F according to the modified example F in the types and positions of the regulating valves 8G. Further, when the compressor 31 related to the air conditioner 1G is driven and the stop compressor 32 stops driving, the inside of the dome 32a of the stop compressor 32 is discharged from the high-pressure compression element 32d of the compressor 32. It becomes a state filled with high-pressure refrigerant.

  Then, the adjustment valve 8G related to the air conditioner 1G is similar to the modified example A in that the medium pressure discharge side stop valves (corresponding to the close valves) 83G and 84G, the low pressure side check valves 85G and 86G, and the medium pressure suction side reverse valve It consists of stop valves 87G and 88G.

  That is, the intermediate pressure discharge side stop valves 83G and 84G are respectively provided on the intermediate pressure pipe p2, and are constituted by electromagnetic valves. The intermediate pressure discharge side stop valves 83G and 84G are in an “open” state when the compressors 31 and 32 are driven, and when the corresponding compressors 31 and 32 are stopped from driving. , “Closed” state. Thereby, when the stop compressor 32 stops driving, it is possible to reliably prevent the refrigerant and the accompanying refrigeration oil from flowing out. In addition, control of the opening / closing operation | movement of the intermediate pressure discharge side stop valve 83G and 84G is performed by the control part which is not shown in figure.

  The low pressure side check valves 85G and 86G are provided on the low pressure suction pipes p31a and p32a. The low pressure side check valves 85G and 86G allow only the flow of refrigerant from the low pressure pipe p3 toward the compressors 31 and 32, particularly the stop compressor 32, and conversely the low pressures from the compressors 31 and 32, particularly the stop compressor 32. The refrigerant flowing toward the pipe p3 is blocked. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes high when the drive is stopped, the refrigeration oil does not flow out from the suction side of the stop compressor 32 to the low pressure pipe p3 side. Insufficient refrigeration oil during startup is less likely to occur.

  The intermediate pressure suction side check valves 87G and 88G are provided in the suction side intermediate pressure branch pipes p25 and p26 of the intermediate pressure pipe p2. The medium pressure suction side check valves 87G and 88G allow the flow of refrigerant from the suction side medium pressure mother pipe p24 to the compressors 31 and 32, particularly the suction port of the high pressure compression element 32d of the stop compressor 32, and conversely. The refrigerant flow from the suction port of the high-pressure compression element 32d toward the suction-side intermediate pressure mother pipe p24 is blocked. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes high when the drive is stopped, the refrigeration oil flows out from the suction side of the high pressure compression elements 31e, 32e of the stop compressor 32 to the intermediate pressure pipe p2. Therefore, the shortage of refrigerating machine oil when starting the stop compressor 32 is less likely to occur.

(4-8) Modification H
Here, similarly to the above-described modification F, the case where the compressors 31 and 32 at the time of driving are of a low pressure dome type and the stop compressor 32 stops driving while the inside of the dome 32a is at a low pressure will be described. .

  FIG. 11 is a schematic configuration diagram of an air conditioner 1H according to Modification H. The air conditioner 1H is different from the air conditioner 1F according to the modified example F in the types and positions of the regulating valves 8H. Further, when the compressor 31 related to the air conditioner 1H is driven and the stop compressor 32 stops driving, the inside of the dome 32a of the stop compressor 32 is low-pressure refrigerant sucked from the low-pressure pipe p3 side. It becomes a full state.

  Then, the adjustment valve 8H related to the air conditioner 1H is, similarly to the modified example E, the high pressure side check valves 81H and 82H, the medium pressure discharge side check valves 83H and 84H, and the medium pressure suction side stop valve (the close valve). Equivalent) 87H and 88H.

  That is, the high pressure side check valves 81H and 82H are provided on the discharge branch pipes p11b and p12b, respectively. The high-pressure check valves 81H and 82H allow the refrigerant to flow from the discharge ports of the compressors 31 and 32, particularly the stop compressor 32, to the high-pressure pipe p1, and conversely, from the high-pressure pipe p1 to the compressors 31 and 32, The refrigerant flow toward the discharge port of the stop compressor 32 is blocked. Thereby, in the stop compressor 32 in which the inside of the dome 32a becomes low pressure when the drive is stopped, the refrigeration oil does not flow out from the high-pressure pipe p1 side to the high-pressure discharge side of the stop compressor 32. Therefore, the stop compressor 32 Insufficient refrigeration oil when starting up is less likely to occur.

  The intermediate pressure discharge side check valves 83H and 84H are respectively connected between the discharge ports of the oil separators 25a and 26a and the discharge side intermediate pressure mother pipe p23. The medium pressure discharge check valves 83H and 84H allow the flow of refrigerant from the low pressure compression elements 31e and 32e toward the high pressure compression elements 31d and 32d, and conversely from the high pressure compression elements 31d and 32d. The refrigerant flow toward 31e and 32e is blocked. As a result, in the stop compressor 32 in which the inside of the dome 32a is at a low pressure when the drive is stopped, the refrigeration oil does not flow out from the intermediate pressure pipe p2 side to the intermediate pressure discharge side of the stop compressor 32. A shortage of refrigerating machine oil when starting the machine 32 is less likely to occur.

  The medium pressure suction side closing valves 87H and 88H are provided in the suction side medium pressure branch pipes p25 and p26 of the medium pressure pipe p2, and are constituted by electromagnetic valves. The intermediate pressure suction side shut-off valves 87H and 88H are in an “open” state when the compressors 31 and 32 are driven, and when the corresponding compressors 31 and 32 are stopped from driving. , “Closed” state. Thereby, when the stop compressor 32 stops driving, it is possible to reliably prevent the refrigerant and the accompanying refrigeration oil from flowing out. Note that the control of the opening / closing operation of the intermediate pressure suction side closing valves 87H, 88H is performed by a control unit (not shown).

(4-9) Modification I
In the above-described embodiment and the modifications A to H, the case where each of the compressors 31 and 32 includes the two-stage compression elements 31d, 31e, 32d, and 32e has been described. However, each compressor 31, 32 may have a plurality of compression elements that are two or more stages.

  In FIG. 12, as an example, among the air conditioners in which each of the compressors 31I and 32I has a four-stage compression element, other than the heat source side heat exchanger, the expansion mechanism, and the use side heat exchanger are excluded. The components are extracted and shown.

  In FIG. 12, the compression mechanism 3I is configured by connecting two compressors 31I and 32I in parallel. The compressors 31I and 32I include, in one dome 31a and 32a, low pressure compression elements 31e and 32e, first intermediate pressure compression elements 31f and 32f, second intermediate pressure compression elements 31g and 32g, and high pressure compression elements 31d and 32d. Have. The first intermediate pressure compression elements 31f and 32f further increase the refrigerant pressure than the low pressure compression elements 31e and 32e, and the second intermediate pressure compression elements 31g and 32g are higher than the first intermediate pressure compression elements 31f and 32f. Will further increase the capacity of the refrigerant. Each of the high-pressure compression elements 31d and 32d further enhances the refrigerant capacity as compared with each of the second intermediate-pressure compression elements 31g and 32g. The four stages of compression elements 31e, 31f, 31g, 31d included in the compressor 31I are connected in series, and the pressure of the refrigerant is sequentially increased. Similarly, the four-stage compression elements 32e, 32f, 32g, and 32d included in the compressor 32I are connected in series, and the pressure of the refrigerant is sequentially increased.

  In FIG. 12, as an example, each of the second intermediate pressure compression elements 31g and 32g is configured to temporarily discharge the compressed refrigerant into the dome 31a and 32a of its compressor 31I and 32I. Therefore, it can be said that the second intermediate pressure compression elements 31g and 32g are internal discharge compressors. The second intermediate pressure discharge pipes p41 and p42 are directly connected to the domes 31a and 32a, respectively. With this configuration, the refrigerant once discharged into the respective domes 31a and 32a by the second intermediate pressure compression elements 31g and 32g is transferred to the domes 31a and 32a of the compressors 31 and 32 by the second intermediate pressure discharge pipes p41 and p42. It is discharged outside. The other compression elements (specifically, the low pressure compression elements 31e and 32e, the first intermediate pressure compression elements 31f and 32f, and the high pressure compression elements 31d and 32d) are connected to the discharge pipes p61a, p62a, p51a, p52a, p11a, and p12a. The refrigerant discharged from each compression element is discharged to the outside of the dome 31a, 32a of its own compressor 31I, 32I via the corresponding discharge pipes p61a, p62a, p51a, p52a, p11a, p12a. It is the structure which discharges. Therefore, it can be said that the compression elements 31e, 32e, 31f, 32f, 31d, and 32d other than the second intermediate pressure compression elements 31g and 32g are external discharge compressors.

  Therefore, the compressors 31I and 32I are low-pressure dome-type compressors that are filled with the medium-pressure refrigerant discharged from the second intermediate-pressure compression elements 31g and 32g in the domes 31a and 32a during driving. Here, when the compressor 31I is driven and the compressor 32I stops driving, the inside of the dome 32a of the stopped compressor 32I is discharged from the second intermediate pressure compression elements 31g and 32g as in driving. Take as an example the case of being filled with the medium pressure refrigerant.

  The air conditioner 1I according to the modified example I connects the second intermediate pressure compression elements 31g and 32g and the high pressure compression elements 31d and 32d of the compressors 31 and 32 in addition to the high pressure pipe p1 and the low pressure pipe p3. First intermediate pressure pipes p41, p42, p43, p44, second intermediate pressure pipes p61, p62, p63, which connect the first intermediate pressure compression elements 31f, 32f and the low pressure compression elements 31e, 32e of the compressors 31, 32, respectively. p64, and third intermediate pressure pipes p51, p52, p53, and p54 that connect the intermediate pressure compression elements 31g, 32g, 31f, and 32f of the compressors 31 and 32 to each other.

  Then, oil separation mechanisms 21I, 22I are provided in the pipes p11a, p12a, p41a, p42a, p51a, p52a, p61a, p62a on the discharge side of the compression elements 31d, 32d, 31g, 32g, 31f, 32f, 31e, 32e. , 23I, 24I, 25I, 26I, 27I, and 28I are provided one by one. Of the oil return pipes 21c to 28c of the oil separation mechanisms 21I to 28I, the oil return pipes 21c and 22c compress the refrigerating machine oil in the refrigerant discharged from the high-pressure compression elements 31d and 32d, respectively, including the elements 31d and 32d. Return to the suction side of the internal discharge compression elements (that is, the second intermediate pressure compression elements 31g, 32g) of the machines 31, 32 themselves. The oil return pipes 23c and 24c are used for the second intermediate pressure compression elements 31g and 32g, that is, the refrigerating machine oil in the refrigerant discharged from the internal discharge compression elements respectively in the compressors 31 and 32 themselves including the elements 31d and 32d. Instead, it is returned to the suction side of the internal discharge compression elements (that is, the second intermediate pressure compression elements 31g and 32g) of the other compressors 31 and 32. That is, the oil return pipes 23c and 24c are in a state of brushing. The oil return pipes 25c and 26c are used to convert the refrigeration oil in the refrigerant discharged from the first intermediate pressure compression elements 31f and 32f into the internal discharge compression elements (that is, the compressors 31 and 32 including the elements 31f and 32f). Return to the suction side of the second intermediate pressure compression elements 31g, 32g), that is, to the suction side of the second intermediate pressure compression elements 31g, 32g, which is one stage above the first intermediate pressure compression elements 31f, 32f. The oil return pipes 27c and 28c are used for the refrigerating machine oil in the refrigerant discharged from the low pressure compression elements 31e and 32e, respectively, of the first intermediate pressure compression elements 31f and 32f of the compressors 31 and 32 themselves including the elements 31e and 32e. Return to suction side. That is, the refrigerating machine oil in the refrigerant discharged from the compression elements 31d and 32d downstream from the internal discharge compression elements 31g and 32g is the internal discharge compression element of the compressor itself having the compression element from which the refrigerant flows out. The refrigerating machine oil in the refrigerant returned to the suction side of 31g, 32g and discharged from the internal discharge compression elements 31g, 32g is not its own compressor but the internal discharge compression elements 31g, 32g of the other compressors 31, 32. It is returned to the suction side. In addition, the refrigeration oil in the refrigerant discharged from the compression elements 31e, 32e, 31f, and 32f, which are upstream of the internal discharge compression elements 31g and 32g, in the compressor itself having the compression element that is the outflow source of the refrigerant, The refrigerant is returned to the suction side of the compression element that is the next stage of the compression element from which the refrigerant flows out.

  The refrigerant discharged from each of the oil separation mechanisms 21I to 28I is cooled by the intermediate cooler 7, and then sucked into a compression element that is downstream of the compression element that discharged the refrigerant.

  The adjustment valve 8I includes high pressure discharge side check valves 81I and 82I, high pressure suction side stop valves 83I and 84I, second intermediate pressure discharge side check valves 85I and 86I, first intermediate pressure discharge side check valves 87I and 88I, Second intermediate pressure suction side check valves 89I and 90I, low pressure discharge side closing valves 91I and 92I, and low pressure suction side check valves 93I and 94I are provided. The high pressure discharge side check valves 81I and 82I are provided on the discharge branch pipes p11b and p12b connected to the high pressure pipe p1. The high pressure suction side stop valves 83I and 84I are provided in the vicinity of the suction side of the high pressure compression elements 31d and 32d on the first medium pressure pipes p43, p44, p41b and p42b. The valves 85I and 86I are provided on the first intermediate pressure pipes p43, p44, p41b, and p42b and between the discharge ports of the compressors 31 and 32 and the intercooler 7. The first intermediate pressure discharge check valves 87I and 88I are provided on the third intermediate pressure pipes p51b and p52b. The second intermediate pressure suction side check valves 89I and 90I are provided in the vicinity of the suction of the first intermediate pressure compression elements 31f and 32f on the second intermediate pressure pipes p63, p64, p61b, and p62b. The low pressure discharge side stop valves 91I and 92I are provided on the second intermediate pressure pipes p63, p64, p61b, and p62b and between the discharge ports of the low pressure compression elements 31e and 32e and the intermediate cooler 7. . The low pressure suction side check valves 93I and 94I are provided on the low pressure suction pipes p31a and p32a branched from the low pressure pipe p3.

  The various check valves 81I to 82I and 85I to 88I located on the discharge side of the compressors 31I and 32I allow only the refrigerant flow from the various discharge ports of the compressors 31I and 32I to the outside of the compressors 31I and 32I. Conversely, the flow of refrigerant from the outside of the compressors 31I, 32I to the various discharge ports of the compressors 31I, 32I is blocked. The various check valves 89I to 90I and 93I to 94I located on the suction side of the compressors 31I and 32I allow only the refrigerant flow from the outside of the compressors 31I and 32I to the various suction ports of the compressors 31I and 32I. Conversely, the flow of refrigerant from the various suction ports of the compressors 31I and 32I to the outside of the compressors 31I and 32I is blocked. The various shut-off valves 83I to 84I and 91I to 92I are composed of electromagnetic valves. When the compressors 31I and 32I are driven, they are in an “open” state, and the corresponding compressors 31I and 32I When the drive is stopped, the state is “closed”.

  That is, the pipes p11b, p12b, p41b, p42b, p51b, p52b, p63, p64, in which a phenomenon occurs in which the refrigerant flow direction is reversed between when the compressors 31I and 32I are driven and when the compressors 31I and 32I are stopped, is determined. Check valves 81I to 82I, 85I to 90I, 93I to 94I are provided as adjusting valves 8I on p31a and p32a. The check valves 83I to 84I and 91I to 92I are provided in the pipes p43, p44, p61b, and p62b in which the refrigerant flows in the same direction when the compressors 31I and 32I are driven and stopped due to the pressure relationship of the refrigerant. Provided as a regulating valve 8I.

  For example, when the compressor 31I is driven by the adjustment valve 8I and the compressor 32 is stopped (for example, the stop compressor 32I), the stop compressor 32I includes the high pressure pipe p1 and the first intermediate pressure pipes p41 and p42. , P43, p44, the second intermediate pressure pipes p61, p62, p63, p64, the low pressure pipe p3, and the third intermediate pressure pipes p51, p52, p53, p54, and allow other refrigerants to flow. No refrigerant flows between the two. Thereby, even when the two compressors 31I and 32I each having two or more stages of compression elements are connected in parallel, the inside of the stop compressor 32 can be equalized.

  The regulating valve 8I described above is an example of the case where the inside of the dome 32a of the stop compressor 32 is filled with the refrigerant discharged from the second intermediate pressure compression element 32g that is one stage before the high pressure compression element 32d. The number and type of the regulating valves 8I are as in the above-described modified examples A to H depending on which compression element the dome of the stop compressor is filled with the refrigerant discharged from the compressor or the refrigerant sucked into the stop compressor. Can be changed. For example, when the inside of the dome 32a of the stop compressor 32 is filled with the high-pressure refrigerant discharged from the high-pressure compression element 32d, the number of solenoid valves is reduced on the suction side compared with FIG. It is necessary to change the check valve to a solenoid valve.

(4-10) Modification J
In the above-described embodiment, the air conditioner capable of cooling operation using the two-stage compression refrigeration cycle has been described. However, in addition to the configuration of FIG. 1, the air conditioner switches between cooling operation and heating operation. By providing the mechanism, the cooling operation and the heating operation can be switched.

  FIG. 13 is a schematic configuration diagram of an air-conditioning apparatus 1J according to Modification J. As shown in FIG. 13, the air conditioner 1 </ b> J includes switching mechanisms 9 a and 9 b and a receiver for enabling switching between the cooling operation and the heating operation in the configuration of the refrigerant circuit 2 (see FIG. 1) of the above-described embodiment. 10, an economizer heat exchanger 12, a bridge circuit 13, and a supercooling heat exchanger 16 are mainly added, and a refrigerant circuit 2J provided with a first expansion mechanism 5a and two second expansion mechanisms 5c instead of the expansion mechanism 5 is provided. It is prepared for. Moreover, it replaces with the utilization side heat exchanger 6 of FIG. 1, and the two utilization side heat exchangers 6a are connected in parallel.

  The switching mechanisms 9a and 9b are mechanisms for switching the direction of refrigerant flow in the refrigerant circuit 2J. During the cooling operation, the switching mechanism 9a uses the heat source side heat exchanger 4 as a radiator for the refrigerant discharged from the compression mechanism 3 and the use side heat exchanger 6 for the refrigerant cooled in the heat source side heat exchanger 4. In order to function as an evaporator, the high pressure pipe p1 of the compression mechanism 3 and one end of the heat source side heat exchanger 4 are connected, and the low pressure pipe p3 of the compression mechanism 3 and the other end of each use side heat exchanger 6a are connected. (Refer to the solid line of the switching mechanism 9a in FIG. 4, and the state of the switching mechanism 9a is hereinafter referred to as “cooling operation state”). On the other hand, during the heating operation, the switching mechanism 9a is cooled by the use side heat exchanger 6 as a radiator for the refrigerant discharged from the compression mechanism 3 and the heat source side heat exchanger 4 in the use side heat exchanger 6. In order to function as a refrigerant evaporator, the high pressure pipe p1 of the compression mechanism 3 and the other end of each use side heat exchanger 6a are connected, and the low pressure pipe p3 of the compression mechanism 3 and one end of the heat source side heat exchanger 4 are connected to each other. (Refer to the broken line of the switching mechanism 9a in FIG. 4, that is, the heating operation state). The switching mechanism 9b causes the refrigerant discharged from the low-pressure compression elements 31e and 32e to be sucked into the high-pressure compression elements 31d and 32d after passing through the intermediate cooler 7 during the cooling operation, and each low-pressure compression element during the heating operation. The refrigerant discharged from 31e and 32e is sucked into the high-pressure compression elements 31d and 32d without passing through the intercooler 7. Thus, in the heating operation, since the refrigerant discharged from the low pressure compression elements 31e and 32e is sucked into the high pressure compression elements 31d and 32d without going through the intermediate cooler 7, heating is performed in the same manner as in the cooling operation. Compared with the case where the intermediate cooler 7 is used in operation, the temperature of the refrigerant discharged from the compression mechanism 3 can be suppressed from decreasing. Therefore, in this air conditioner 1J, it is possible to suppress heat radiation to the outside, and to suppress a decrease in the temperature of the refrigerant supplied to the use-side heat exchanger 6a that functions as a refrigerant radiator, resulting in a decrease in operating efficiency. Can be prevented.

  Note that the switching mechanisms 9a and 9b are not limited to the four-way switching valves, and are configured to have the same function of switching the refrigerant flow direction as described above, for example, by combining a plurality of electromagnetic valves. It may be a thing.

  The receiver 10 is depressurized by the first expansion mechanism 5a so as to be able to store surplus refrigerant that is generated in accordance with an operation state such as a difference in the circulation amount of the refrigerant in the refrigerant circuit 2J between the cooling operation and the heating operation. It is the container provided in order to accumulate the refrigerant | coolant after a short time. Therefore, the inlet of the receiver 10 is connected to the receiver inlet pipe 10a, and the outlet thereof is connected to the receiver outlet pipe 10b. The receiver 10 also has a suction return pipe that can extract the refrigerant from the receiver 10 and return it to the suction side of the compression mechanism 3 (that is, the suction ports of the low-pressure compression elements 31e and 32e of the compressors 31 and 32). 30 is connected. The suction return pipe 30 is provided with a suction return on / off valve 30a composed of an electric valve.

  The economizer heat exchanger 12 includes a refrigerant flowing between the heat source side heat exchanger 4 and each use side heat exchanger 6a and a refrigerant flowing through the injection pipe 11 (more specifically, to the vicinity of the intermediate pressure in the injection on-off valve 11a). It is a heat exchanger that performs heat exchange with the refrigerant after being depressurized. In this modification, the economizer heat exchanger 12 is positioned upstream of the first expansion mechanism 5a of the receiver inlet pipe 10a (that is, when the switching mechanism 9a is in the cooling operation state, the heat source side heat exchanger 4 And a refrigerant flowing between the first expansion mechanism 5a and the refrigerant flowing through the injection pipe 11, and has a flow path through which both refrigerants face each other. . The economizer heat exchanger 12 causes the refrigerant flowing between the heat source side heat exchanger 4 and each use side heat exchanger 6a to be injected before being heat exchanged in the economizer heat exchanger 12 in the receiver inlet pipe 10a. After branching to the tube 11, the economizer heat exchanger 12 performs heat exchange with the refrigerant flowing through the injection tube 11.

  Here, the injection pipe 11 has a function of branching the refrigerant flowing between the heat source side heat exchanger 4 and each use side heat exchanger 6a and returning it to the high pressure compression elements 31d and 32d. The injection pipe 11 is provided with an injection opening / closing valve 11a capable of opening degree control. The injection on / off valve 11a is constituted by an electric expansion valve.

  The bridge circuit 13 is provided between the heat source side heat exchanger 4 and each use side heat exchanger 6a, and is connected to the receiver inlet pipe 10a and the receiver outlet pipe 10b of the receiver 10. The bridge circuit 13 has three check valves 13a, 13c, 13d and one expansion valve 13b in this modification. The inlet check valve 13a only allows the refrigerant to flow from the heat source side heat exchanger 4 to the receiver inlet pipe 10a, and the inlet expansion valve 13b is the refrigerant from the receiver outlet pipe 10b to the heat source side heat exchanger 4. Open and close the distribution of The outlet check valve 13c only allows the refrigerant to flow from the receiver outlet pipe 10b to the usage-side heat exchanger 6, and the outlet check valve 13d passes the refrigerant from the receiver outlet pipe 10b to the receiver inlet pipe 10a. Only tolerate.

  The supercooling heat exchanger 16 is a heat exchanger that cools the refrigerant sent from the receiver 10 to each second expansion mechanism 5c. More specifically, the supercooling heat exchanger 16 branches a part of the refrigerant sent from the receiver 10 to each of the second expansion mechanisms 5c during the cooling operation, so that the suction side (specifically, the compressors 31 and 32) Is a heat exchanger for exchanging heat with the refrigerant flowing through the suction return pipe 16a returning to the suction side of the low-pressure compression elements 31e, 32e, and has a flow path through which both refrigerants face each other. . Here, the suction return pipe 16a branches the refrigerant sent from the heat source side heat exchanger 4 as a radiator to each second expansion mechanism 5c and returns it to the suction side of the compression mechanism 3 (that is, the low pressure pipe p3). It is a tube. The suction return pipe 16a is provided with a suction return valve 16b whose opening degree can be controlled. In the supercooling heat exchanger 16, the refrigerant sent from the receiver 10 to each second expansion mechanism 5c and the suction return valve 16b. In this case, heat exchange with the refrigerant flowing through the suction return pipe 16a after the pressure is reduced to near low pressure is performed. The suction return valve 16b is an electric expansion valve in this modification.

  The first expansion mechanism 5a is a mechanism that depressurizes the refrigerant provided in the receiver inlet pipe 10a, and an electric expansion valve is used in this modification. Further, in the present modification, the first expansion mechanism 5a, during the cooling operation, converts the high-pressure refrigerant cooled in the heat source side heat exchanger 4 into the refrigerant before sending it to each use side heat exchanger 6a via the receiver 10. The pressure is reduced to around the saturation pressure. During the heating operation, the first expansion mechanism 5a depressurizes the high-pressure refrigerant cooled in each use-side heat exchanger 6a to near the saturation pressure of the refrigerant before sending it to the heat source side heat exchanger 4 via the receiver 10. .

  The second expansion mechanism 5c is provided between the subcooling heat exchanger 16 and each use side heat exchanger 6a. The second expansion mechanism 5c is a mechanism that depressurizes the refrigerant that has flowed out of the supercooling heat exchanger 16, and an electric expansion valve is used in this modification.

  In addition to the above, the air conditioner 1J includes a check valve 7a provided on the downstream side of the intermediate cooler 7, a switching mechanism 9b, and intermediate pressure pipes p2 and suction side intermediate pressure branch pipes p25 and p26. Is provided with a check valve 9c. The check valve 7a allows only the flow of refrigerant from the intermediate cooler 7 toward the high pressure compression elements 31d and 32d, and the check valve 9c allows the refrigerant to flow from the switching mechanism 9b to the high pressure compression elements 31d and 32d. Only the flow of is allowed. Further, the air conditioner 1J includes an electromagnetic valve 19a that opens and closes between the discharge-side intermediate-pressure mother pipe p23 and the low-pressure pipe p3, which are medium-pressure pipes p2, and each suction-side medium that is the high-pressure pipe p1 and the intermediate-pressure pipe p2. An electromagnetic valve 19b that opens and closes between the pressure branch pipes p25 and p26 is provided. Each solenoid valve 19a, 19b is for maintaining the pressure equalization in the stopped compressor more reliably in a state where any one of the compressors is stopped.

<Other embodiments>
As mentioned above, although embodiment of this invention and its modification were demonstrated based on drawing, specific structure is not restricted to these embodiment and its modification, It changes in the range which does not deviate from the summary of invention. Is possible.

(A)
In the above-described embodiment and modification, the case where carbon dioxide is used as the refrigerant and the two-stage compression refrigeration cycle operating in the supercritical region is performed has been described. However, the refrigeration apparatus of the present invention may not operate in the supercritical region, and therefore the refrigerant may be other than carbon dioxide. R1234 etc. are mentioned as refrigerant | coolants other than a carbon dioxide.

(B)
In the above-mentioned embodiment and modification, the case where the stop compressor was the compressor 32 was demonstrated as an example. However, in the present invention, since any one of the compressors 31 and 32 is stopped (that is, the stopped compressor) and the other compressor is driven, the stopped compressor may be the compressor 31. .

(C)
In the above-described embodiment and modification, as an example, it has been described that the compression mechanism 3 is configured by the parallel connection of the two compressors 31 and 32. However, the number of compressors may be plural, and therefore the compression mechanism may be configured by connecting three or more compressors in parallel.

(D)
In the above-described embodiment and modification examples A to I, the case where the air conditioners 1 and 1A to 1I are devices that perform a cooling operation has been described. That is, the case where the heat source side heat exchanger 4 functions as a refrigerant cooler and the use side heat exchanger 6 functions as a refrigerant heater has been described. However, the air conditioners 1 and 1A to 1I of the above-described embodiment and the modifications A to I may be devices that perform only the heating operation, not the cooling operation.

  The refrigeration apparatus of the present invention is a stop compression unit in which any one of a plurality of compression units stops driving, and when the other compression unit is driven, the inside of the stop compression unit is equalized. Can be. Therefore, the refrigeration apparatus of the present invention has a compression mechanism in which a plurality of compression units having a plurality of stages of compression elements that increase the pressure of the refrigerant are connected in parallel, and any one of the compression units stops driving. It can be applied to devices driven by other compressors.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Refrigerant circuit 3 Compression mechanism 4 Heat source side heat exchanger 5 Expansion mechanism 6 Use side heat exchanger 7 Intermediate cooler 8 Control valve p1 High pressure piping p2 Medium pressure piping p3 Low pressure piping 21, 22, 25, 26 Oil Separation mechanism 21a, 22a, 25a, 26a Oil separator 21b, 22b, 25b, 26b Check mechanism 21c, 22c, 25c, 26c Oil return pipe 31, 32 Compressor 31a, 32a Dome 31b, 32b Compressor drive motor 31c, 32c Drive shaft 31d, 32d High pressure compression element 31e, 32e Low pressure compression element 31f, 32f First intermediate pressure compression element 31g, 32g Second intermediate pressure compression element 81, 82 High pressure side check valve 81I, 82I High pressure discharge side check valve 83, 84 Medium pressure side check valve 83A, 84A Medium pressure discharge side stop valve 83B, 84B Medium pressure discharge side check valve 83I, 84I High pressure suction side stop valve 85, 6 Low pressure side check valves 85I, 86I Second medium pressure discharge side check valves 87A, 88A Medium pressure suction side check valves 87B, 88B Medium pressure suction side stop valves 87I, 88I First medium pressure discharge side check valves 89I , 90I Second medium pressure suction side check valves 91I, 92I Low pressure discharge side stop valves 93I, 94I Low pressure suction side check valves p41, p42, p43, p44 First medium pressure pipes p61, p62, p63, p64 Second middle Pressure piping p51, p52, p53, p54 Third medium pressure piping

JP 2009-133583 A

Claims (8)

A plurality of compression sections (31, 32) having a low pressure compression element (31e, 32e) for increasing the pressure of the refrigerant and a high pressure compression element (31d, 32d) for increasing the pressure of the refrigerant further than the low pressure compression element are connected in parallel. A compression mechanism (3),
A heat source side heat exchanger (4) functioning as a refrigerant cooler or heater;
An expansion mechanism (5) for depressurizing the refrigerant;
A use side heat exchanger (6) that functions as a refrigerant heater or cooler;
A high-pressure pipe (p1) through which a high-pressure refrigerant discharged from the high-pressure compression elements of the plurality of compression units flows;
An intermediate pressure pipe (p2) that connects the high pressure compression element and the low pressure compression element in each compression section and through which an intermediate pressure refrigerant flows;
A low-pressure pipe (p3) through which a low-pressure refrigerant sucked into the low-pressure compression elements of the plurality of compression sections flows;
When any one of the plurality of compression units (hereinafter referred to as a stop compression unit) stops driving and the remaining compression units are driven, in the stop compression unit, the high pressure pipe and the medium pressure pipe And a regulating valve that adjusts the communication state between the stop compression section and each of the pipes so that only one of the low-pressure pipes allows the flow of the refrigerant and no refrigerant flows between the other pipes. (8) and
A refrigeration apparatus (1). Each of the compression units is a compressor that houses the high-pressure compression element and the low-pressure compression element in one dome.
The refrigeration apparatus (1) according to claim 1. The stop compression unit stops driving in a state where the refrigerant discharged from the high pressure compression element or the low pressure compression element of the stop compression unit is filled in the dome,
The regulating valve has a low pressure side check valve (85, 86) that allows only a flow of refrigerant from the low pressure pipe toward the stop compression unit,
The refrigeration apparatus (1) according to claim 1 or 2. The stop compression unit stops driving in a state where the refrigerant discharged from the low pressure compression element of the stop compression unit is filled in the dome,
The regulating valve is
An intermediate pressure check valve (83, 84) that allows only the flow of refrigerant from the low pressure compression element to the high pressure compression element of the stop compression section in the intermediate pressure pipe;
High pressure side check valves (81, 82) that allow only the flow of refrigerant from the stop compression section toward the high pressure pipe;
Further having
The refrigeration apparatus (1) according to claim 3. The regulating valve is
A stop valve (83A, 83A) provided in the intermediate pressure pipe in which the direction in which the refrigerant flows out in the state where the stop compression unit stops driving is the same as that in the drive state of the stop compression unit due to the pressure relationship of the refrigerant. 84A, 83D, 84D, 83G, 84G, 87B, 88B, 87E, 88E, 87H, 88H),
Further having
The refrigeration apparatus (1) according to any one of claims 1 to 3. The stop valve is configured such that when the stop compression unit stops driving in a state where the refrigerant discharged from the high pressure compression element is filled in the dome, or the refrigerant sucked from the low pressure side suction pipe is in the dome. Provided in the intermediate pressure pipe when the drive is stopped in a state where
The refrigeration apparatus (1) according to claim 5. Low pressure compression elements (31e, 32e) for increasing the pressure of the refrigerant, intermediate pressure compression elements (31f, 32f, 31g, 32g) for increasing the pressure of the refrigerant further than the low pressure compression elements, and refrigerant further than the intermediate pressure compression elements A compression mechanism (3I) in which a plurality of compression sections having high-pressure compression elements (31d, 32d) for increasing the pressure of
A heat source side heat exchanger (4) functioning as a refrigerant cooler or heater;
An expansion mechanism (5) for depressurizing the refrigerant;
A use side heat exchanger (6) that functions as a refrigerant heater or cooler;
A high-pressure pipe (p1) through which a high-pressure refrigerant discharged from the high-pressure compression elements of the plurality of compression units flows;
A first intermediate pressure pipe (p41, p42, p43, p44) connecting the intermediate pressure compression element and the high pressure compression element in each compression section;
A second intermediate pressure pipe (p61, p62, p63, p64) connecting the intermediate pressure compression element and the low pressure compression element in each compression section;
A low-pressure pipe (p3) through which a low-pressure refrigerant sucked into the low-pressure compression elements of the plurality of compression sections flows;
When any one of the plurality of compression units (hereinafter referred to as a stop compressor) stops driving and the remaining compression units are driven, in the stop compression unit, the high pressure pipe, the first medium The stop compression section and each of the pipes so that the refrigerant flows only between one of the pressure pipe, the second intermediate pressure pipe, and the low-pressure pipe and does not flow between the other pipes. An adjustment valve (8I) for adjusting the communication state with
A refrigeration apparatus (1I). The compression unit has a plurality of the intermediate pressure compression elements,
One or a plurality of third intermediate pressure pipes (p51, p52, p53, p54) that connect the intermediate pressure compression elements of each compression section;
Further comprising
The regulating valve is only one of the high pressure pipe, the first medium pressure pipe, the second medium pressure pipe, the low pressure pipe, and one or a plurality of the third medium pressure pipes in the stop compression unit. Adjusting the communication state between the stop compression unit and each of the pipes so that the refrigerant flow is allowed and no refrigerant flows between the pipes;
The refrigeration apparatus (1I) according to claim 7.

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