KR20100095601A - Refrigeration device - Google Patents

Abstract

The air conditioner 1 uses carbon dioxide as a refrigerant, a two-stage compression type compression mechanism 2, a heat source side heat exchanger 4, an expansion mechanism 5, and a use side heat exchanger 6. ) And an intermediate refrigerant pipe 8 for sucking the refrigerant discharged from the compression element on the front end side into the compression element on the rear end side, and is discharged from the compression element on the front side and compressed on the rear end side. The intermediate cooler 7 which functions as a cooler of the refrigerant sucked into the cooling medium, and a portion between the compression element on the front end side of the intermediate refrigerant pipe 8 and the inlet of the intermediate cooler 7, It has an intermediate oil separation mechanism 16 which separates the refrigerator oil accompanying the discharged refrigerant from the refrigerant and returns it to the suction side of the compression mechanism 2.

Description

Refrigeration unit {REFRIGERATION DEVICE}

TECHNICAL FIELD The present invention relates to a refrigerating device, particularly a refrigerating device that performs a multi-stage compression refrigeration cycle using a refrigerant operating in a supercritical zone.

Conventionally, an air conditioner that performs a two-stage compression refrigeration cycle using carbon dioxide as a refrigerant as one of the refrigeration apparatuses that performs a multistage compression refrigeration cycle using a refrigerant operating in a supercritical region. There is. The air conditioner mainly includes a compressor having two compression elements connected in series, an outdoor heat exchanger as a heat source side heat exchanger, an expansion valve, and an indoor heat exchanger.

Japanese Patent Laid-Open No. 2007-232263

A refrigeration apparatus according to the first invention is a refrigeration apparatus using a refrigerant operating in a supercritical region, and includes a compression mechanism, a heat source side heat exchanger, an expansion mechanism for depressurizing the refrigerant, a use side heat exchanger, an intermediate cooler, and an intermediate An oil separation mechanism is provided. The compression mechanism has a plurality of compression elements, and is configured to sequentially compress the refrigerant discharged from the compression element on the front end side of the plurality of compression elements to the compression element on the rear end side. Here, the "compression mechanism" includes connecting a plurality of compressors in which a plurality of compression elements are integrated, a compressor in which a single compression element is incorporated, and / or a compressor in which a plurality of compression elements are incorporated. It means configuration. In addition, "compressing the refrigerant | coolant discharged from the compression element of the front side among the several compression elements sequentially by the compression element of the rear side" is connected in series as "compression element of a front side" and "compression element of a rear side". Not only does it mean to include two compression elements, but a plurality of compression elements are connected in series, and the relationship between each of the compression elements is the aforementioned "compression element on the front side" and "compression element on the rear side". It means having a relationship of ". The intermediate cooler is a cooler for the refrigerant which is installed in the intermediate refrigerant pipe for sucking the refrigerant discharged from the compression element on the front side into the compression element on the rear end side, and is discharged from the compression element on the front side and sucked into the compression element on the rear end side. Function. The intermediate oil separation mechanism is provided at a portion between the compression element on the front end side of the intermediate refrigerant pipe and the inlet of the intermediate cooler, and separates the refrigerant oil accompanying the refrigerant discharged from the compression element on the front side side from the refrigerant and It is a mechanism to return to the suction side.

In the conventional air conditioner, when the heat exchanger which uses air as a heat source is adopted as an outdoor heat exchanger, the critical temperature (about 31 degreeC) of carbon dioxide used as a refrigerant | coolant is a heat source of the outdoor heat exchanger which functions as a cooler of a refrigerant | coolant. The high pressure of the refrigerating cycle is such that the refrigerant is cooled by the air in the outdoor heat exchanger during the cooling operation as the cooling operation because the temperature is about the same as the temperature of the air, which is lower than that of the refrigerant such as R22 or R410A. Operation is performed at a state higher than the critical pressure of the refrigerant. Due to this, since the temperature of the refrigerant discharged from the compression element on the rear end side of the compressor becomes high, in the outdoor heat exchanger functioning as the cooler of the refrigerant, the temperature difference between the air as the heat source and the refrigerant increases, There is a problem that high operating efficiency is difficult to be obtained because the heat dissipation loss is large.

In this refrigeration apparatus, in this refrigeration apparatus, the intermediate cooler, which functions as a cooler of the refrigerant discharged from the compression element on the front end side and sucked into the compression element on the rear end side, receives the refrigerant discharged from the compression element on the front end side, the compression element on the rear end side. By installing in the intermediate refrigerant pipe for suctioning into the furnace, the temperature of the refrigerant sucked into the compression element on the rear end side is lowered, and as a result, the temperature of the refrigerant discharged from the compression element on the rear end side of the compressor is lowered, It is made to reduce the heat radiation loss in it.

Here, since the refrigerant oil in the compressor is accompanied by the refrigerant discharged from the compression element on the front end side of the compressor, the refrigerant oil in the compressor is taken out of the compressor by the intermediate refrigerant pipe. And as mentioned above, since only the intermediate | middle cooler is provided, since refrigeration oil will collect in an intermediate | middle cooler and will not return to a compressor, there exists a possibility that the oil may run out of a compressor.

However, in this refrigeration apparatus, an intermediate oil separation mechanism is provided, and since refrigeration oil accompanying the refrigerant discharged from the compression element on the front end side can be prevented from flowing into the intermediate cooler, the collection of the refrigeration oil to the intermediate cooler is prevented. This can prevent oil depletion of the compression mechanism. Moreover, the fall of the heat transfer performance of an intermediate | middle cooler by the gathering of the refrigeration oil to an intermediate | middle cooler, and the increase of a pressure loss can be prevented, and the performance of a refrigeration apparatus can be improved.

In particular, when the compression mechanism includes a high pressure dome-type compressor in which a plurality of series-connected compression elements are housed in the same casing, the refrigerant discharged from the compression element on the rear end side is once discharged into the space where the refrigeration oil in the casing is collected. After being discharged to the outside of the casing, the amount of the refrigerant oil accompanying the refrigerant is not large, whereas the refrigerant discharged from the compression element on the front end side is directly discharged to the outside of the casing, so that the amount of the refrigerant oil accompanying the refrigerant is large. Since there is a high possibility that the amount of the refrigeration oil gathered in the intermediate cooler increases, it is very effective to provide the intermediate oil separation mechanism according to the present invention.

The refrigerating device according to the second invention is the refrigerating device according to the first invention, wherein the intermediate oil separation mechanism includes an intermediate oil separator for separating the refrigerant oil accompanying the refrigerant discharged from the compression element on the front end side from the refrigerant. It is connected to an intermediate oil separator and has an intermediate oil return tube for returning the refrigerant oil separated from the refrigerant to the compression mechanism.

In this refrigeration apparatus, since the intermediate oil separator is provided in the vicinity of the compression element on the front end side, the refrigerant oil can be separated from the refrigerant in the vicinity of the compression element on the front end side. It is also possible to prevent the gathering of refrigeration oil.

The refrigeration apparatus according to the third invention is the refrigeration apparatus according to the first invention, wherein the intermediate oil separation mechanism is an intermediate for connecting the header provided at the inlet of the intermediate cooler, the lower end of the header, and the compression mechanism. It has an oil return tube.

In this refrigeration apparatus, since the header provided at the inlet of the intermediate cooler functions as an oil separator, an increase in the device score can be suppressed.

In the refrigerating device according to the fourth invention, in the refrigerating device according to any one of the first to third inventions, the refrigerant operating in the supercritical region is carbon dioxide.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the air conditioner as an Example of the refrigeration apparatus which concerns on this invention.
2 is a pressure enthalpy diagram showing a refrigerating cycle during cooling operation.
3 is a temperature entropy diagram showing a refrigeration cycle during the cooling operation.
4 is a schematic configuration diagram of an intermediate cooler and an intermediate oil separation mechanism in the air conditioner according to Modification Example 1. FIG.
5 is a schematic configuration diagram of an air conditioner according to a second modification.
6 is a schematic configuration diagram of an air conditioner according to a third modification.
7 is a schematic configuration diagram of an air conditioner according to a third modification.
8 is a schematic configuration diagram of an air conditioner according to a third modification.
9 is a pressure enthalpy diagram showing a refrigeration cycle during the cooling operation in the air conditioner according to the third modification.
10 is a temperature entropy diagram showing a refrigeration cycle during cooling operation in the air conditioner according to Modification Example 3. FIG.
11 is a schematic configuration diagram of an air conditioner according to a fourth modification.
12 is a schematic configuration diagram of an air conditioner according to a fifth modification.
13 is a schematic configuration diagram of an air conditioner according to a modification 5. FIG.
14 is a schematic configuration diagram of an air conditioner according to Modification Example 6. FIG.
FIG. 15 is a pressure enthalpy diagram showing a refrigeration cycle during the cooling operation in the air conditioner according to Modification Example 6. FIG.
FIG. 16 is a temperature entropy diagram showing a refrigeration cycle during the cooling operation in the air conditioner according to Modification 6. FIG.
FIG. 17 is a pressure enthalpy diagram showing a refrigeration cycle during heating operation in the air conditioner according to Modification Example 6. FIG.
18 is a temperature entropy diagram showing a refrigeration cycle during heating operation in the air conditioner according to Modification 6. FIG.
19 is a schematic configuration diagram of an air conditioner according to Modification Example 6. FIG.
20 is a schematic configuration diagram of an air conditioner according to a seventh modification example.
21 is a schematic configuration diagram of an air conditioner according to Modification Example 7. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of the refrigeration apparatus which concerns on this invention is described based on drawing.

(1) Configuration of the air conditioner

FIG. 1: is a schematic block diagram of the air conditioner 1 as an Example of the refrigeration apparatus which concerns on this invention. The air conditioner 1 is a device which has a refrigerant | coolant circuit 10 comprised so that a cooling operation can be performed, and performs a 2-stage compression type refrigeration cycle using the refrigerant | coolant (here carbon dioxide) which operates in a supercritical area.

The refrigerant circuit 10 of the air conditioner 1 mainly includes the compression mechanism 2, the heat source side heat exchanger 4, the expansion mechanism 5, the use side heat exchanger 6, and the intermediate cooler 7. Have.

The compression mechanism 2 is comprised by the compressor 21 which compresses a refrigerant | stage two stages with two compression elements in this embodiment. The compressor 21 has a hermetic structure in which the compressor drive motor 21b, the drive shaft 21c, and the compression elements 2c and 2d are accommodated in the casing 21a. The compressor drive motor 21b is connected to the drive shaft 21c. This drive shaft 21c is connected to two compression elements 2c and 2d. That is, in the compressor 21, two compression elements 2c and 2d are connected to a single drive shaft 21c, and the two compression elements 2c and 2d are rotated together by the compressor drive motor 21b. The so-called single-axis two-stage compression structure is driven. The compression elements 2c and 2d are volumetric compression elements, such as rotary type and scroll type, in this embodiment. Then, the compressor 21 sucks the refrigerant from the suction pipe 2a, compresses the sucked refrigerant by the compression element 2c, and then discharges the refrigerant to the intermediate refrigerant pipe 8 to the intermediate refrigerant pipe 8. The discharged refrigerant is sucked into the compression element 2d to further compress the refrigerant, and then discharged to the discharge tube 2b. Here, the intermediate refrigerant pipe 8 sucks the refrigerant discharged from the compression element 2c connected to the front end side of the compression element 2d into the compression element 2d connected to the rear end side of the compression element 2c. It is a refrigerant pipe for making. In addition, the discharge pipe 2b is a refrigerant pipe for sending the refrigerant discharged from the compression mechanism 2 to the heat source side heat exchanger 4, and the discharge pipe 2b includes an oil separation mechanism 41 and a check valve. I) A mechanism 42 is provided. The oil separation mechanism 41 is a mechanism for separating the refrigerant oil accompanying the refrigerant discharged from the compression mechanism 2 from the refrigerant and returning it to the suction side of the compression mechanism 2, and mainly discharged from the compression mechanism 2. An oil separator 41a for separating the refrigerant oil accompanying the refrigerant from the refrigerant, and an oil return pipe connected to the oil separator 41a and returning the refrigerant oil separated from the refrigerant to the suction pipe 2a of the compression mechanism 2. Has 41b. The oil return pipe 41b is provided with a decompression mechanism 41c for depressurizing the refrigeration oil flowing through the oil return pipe 41b. In the present embodiment, the pressure reducing mechanism 41c uses a capillary tube. The check mechanism 42 allows the flow of the refrigerant from the discharge side of the compression mechanism 2 to the heat source side heat exchanger 4, and further, from the heat source side heat exchanger 4 to the discharge side of the compression mechanism 2. A mechanism for interrupting the flow of refrigerant is used. In this embodiment, a check valve is used.

Thus, in this embodiment, the compression mechanism 2 has two compression elements 2c and 2d, and the refrigerant | coolant discharged from the compression element of the front side among these compression elements 2c and 2d is the rear end side. It is configured to sequentially compress with a compression element of.

The heat source side heat exchanger 4 is a heat exchanger which functions as a cooler of a refrigerant. One end of the heat source side heat exchanger 4 is connected to the compression mechanism 2, and the other end thereof is connected to the expansion mechanism 5. In addition, although not shown here, the heat source side heat exchanger 4 is supplied with water or air as a cooling source which heat-exchanges with the refrigerant which flows through the heat source side heat exchanger 4.

The expansion mechanism 5 is a mechanism for reducing the refrigerant, and in this embodiment, an electric expansion valve is used. One end of the expansion mechanism 5 is connected to the heat source side heat exchanger 4, and the other end thereof is connected to the use side heat exchanger 6. In addition, in the present embodiment, the expansion mechanism 5 depressurizes the high pressure refrigerant cooled in the heat source side heat exchanger 4 before sending it to the use side heat exchanger 6.

The utilization side heat exchanger 6 is a heat exchanger which functions as a heater of a refrigerant. One end of the use side heat exchanger 6 is connected to the expansion mechanism 5, and the other end thereof is connected to the compression mechanism 2. In addition, although not shown here, the use-side heat exchanger 6 is supplied with water and air as a heating source which heat-exchanges with the refrigerant which flows through the use-side heat exchanger 6.

The intermediate cooler 7 is a heat exchanger which is provided in the intermediate refrigerant pipe 8 and functions as a cooler for the refrigerant discharged from the compression element 2c on the front end side and sucked into the compression element 2d. In addition, although not shown here, the intermediate | middle cooler 7 is supplied with water and air as a cooling source which heat-exchanges with the refrigerant | coolant which flows through the intermediate | middle cooler 7. In this way, the intermediate cooler 7 may be referred to as a cooler using an external heat source in the sense that the coolant circulating in the coolant circuit 10 is not used.

In addition, an intermediate oil separation mechanism 16 is provided at a portion between the compression element 2c on the front end side of the intermediate refrigerant pipe 8 and the inlet of the intermediate cooler 7. The intermediate oil separation mechanism 16 is a mechanism for separating the refrigerant oil accompanying the refrigerant discharged from the compression element 2c on the front end side from the refrigerant and returning it to the compression mechanism 2. The intermediate oil separation mechanism 16 is mainly connected to an intermediate oil separator 16a for separating refrigerant oil accompanying the refrigerant discharged from the compression element 2c on the front end side from the refrigerant, and an intermediate oil separator 16a. And an intermediate oil return pipe 16b for returning the refrigerant oil separated from the refrigerant to the compression mechanism 2. In this embodiment, the intermediate oil return pipe 16b is connected between the oil outlet of the intermediate oil separator 16a and the suction side of the compression mechanism 2 (here, the suction pipe 2a). A decompression mechanism 16c for depressurizing the refrigeration oil flowing through the oil return pipe 16b is provided. As the pressure reduction mechanism 16c, in this embodiment, a capillary tube is used.

Furthermore, although not shown here, the air conditioner 1 has a control part which controls the operation | movement of each part which comprises the air conditioner 1, such as the compression mechanism 2 and the expansion mechanism 5. As shown in FIG.

(2) the operation of the air conditioner

Next, the operation of the air conditioner 1 of the present embodiment will be described with reference to FIGS. 1 to 3. 2 is a pressure enthalpy diagram in which a refrigeration cycle in a cooling operation is shown, and FIG. 3 is a temperature entropy diagram in which a refrigeration cycle in a cooling operation is shown. In addition, the operation control in the following cooling operation is performed by the above-mentioned control part (not shown). In addition, in the following description, "high pressure" means the high pressure (that is, the pressure in points D, D ', E of FIG. 2, 3) in a refrigeration cycle, and "low pressure" means a refrigeration cycle. Means the low pressure (that is, the pressure at points A and F of FIGS. 2 and 3), and the term "medium pressure" means the medium pressure (ie, the points B1 and C1 of FIGS. 2 and 3) in the refrigerating cycle. Pressure at).

When the compression mechanism 2 is driven, the low pressure refrigerant (see point A in FIGS. 1 to 3) is sucked into the compression mechanism 2 from the suction pipe 2a and, firstly, the intermediate pressure by the compression element 2c. After being compressed to, it is discharged to the intermediate refrigerant pipe 8 (see point B1 in FIGS. 1 to 3). The medium pressure refrigerant discharged from the compression element 2c on the front end side flows into the intermediate oil separator 16a constituting the intermediate oil separation mechanism 16, and after the accompanying refrigerator oil is separated, the intermediate cooler 7 Is sent). In addition, the refrigeration oil separated from the medium pressure refrigerant in the intermediate oil separator (16a) flows into the intermediate oil return pipe (16b) constituting the intermediate oil separation mechanism (16) and enters the intermediate oil return pipe (16b). After the pressure reduction by the provided pressure reduction mechanism 16c is carried out, it returns to the compression mechanism 2 (here, the suction pipe 2a), and is suctioned by the compression mechanism 2 again. Next, the medium pressure refrigerant after the refrigerator oil is separated in the intermediate oil separation mechanism 16 is cooled by performing heat exchange with water or air as a cooling source in the intermediate cooler 7 (FIGS. 1 to 3). See point C1). The refrigerant cooled in the intermediate cooler 7 is then sucked into the compression element 2d connected to the rear end side of the compression element 2c, and further compressed, and discharged from the compression mechanism 2 to the discharge tube 2b. (See point D in Figs. 1 to 3). Here, the high pressure refrigerant discharged from the compression mechanism 2 is subjected to a threshold pressure (that is, a critical pressure Pcp at the critical point CP shown in FIG. 2) by a two-stage compression operation by the compression elements 2c and 2d. Compressed up to pressure. And the high pressure refrigerant | coolant discharged from this compression mechanism 2 flows into the oil separator 41a which comprises the oil separation mechanism 41, and the accompanying refrigerator oil is isolate | separated. In addition, the refrigeration oil separated from the high pressure refrigerant in the oil separator 41a flows into the oil return pipe 41b constituting the oil separation mechanism 41 and is provided with a pressure reducing mechanism 41c provided in the oil return pipe 41b. ), The pressure is returned to the suction pipe 2a of the compression mechanism 2, and then suctioned by the compression mechanism 2 again. Next, the high pressure refrigerant after the refrigeration oil is separated in the oil separation mechanism 41 is sent to the heat source side heat exchanger 4 which functions as a cooler of the refrigerant via the check mechanism 42. Then, the high pressure refrigerant sent to the heat source side heat exchanger 4 is cooled by performing heat exchange with water or air as a cooling source in the heat source side heat exchanger 4 (see point E in FIGS. 1 to 3). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 is reduced in pressure by the expansion mechanism 5 to become a refrigerant in a low-pressure gas-liquid abnormal state, and the use-side heat exchanger 6 which functions as a heater of the refrigerant. (See point F in Figs. 1 to 3). The low-pressure gas-liquid abnormality refrigerant sent to the use-side heat exchanger 6 is then heated and evaporated in the use-side heat exchanger 6 by exchanging heat with water or air as a heating source (FIGS. 1 to 1). See point A in FIG. 3). The low pressure refrigerant heated in the use-side heat exchanger 6 is again sucked into the compression mechanism 2. In this manner, cooling operation is performed.

In this way, in the air conditioner 1, the intermediate cooler 7 is provided in the intermediate refrigerant pipe 8 for sucking the refrigerant discharged from the compression element 2c into the compression element 2d. In the case of not providing (7) (in this case, a refrigeration cycle is performed in the order of point A-point B1-point D '-point E-point F in FIG. 2, FIG. 3). The temperature of the refrigerant sucked into the compression element 2d on the rear end side of (2c) decreases (see points B1 and C1 in FIG. 3), and the temperature of the refrigerant discharged from the compression element 2d also decreases (FIG. 3). See points D and D ′). For this reason, in this air conditioner 1, in the heat source side heat exchanger 4 which functions as a cooler of a high pressure refrigerant | coolant, compared with the case where the intermediate | middle cooler 7 is not provided, water and air as a cooling source, It becomes possible to make small the temperature difference of refrigerant | coolant, and can improve operation efficiency by reducing the heat radiation loss corresponding to the area enclosed by connecting point B1, D ', D, C1 of FIG. You can.

Moreover, in the air conditioner 1, it is discharged from the compression element 2c at the front side to the part between the compression element 2c at the front side of the intermediate refrigerant pipe 8, and the inlet of the intermediate cooler 7. Since the intermediate oil separation mechanism 16 for separating the refrigerant oil accompanying the refrigerant from the refrigerant and returning it to the compression mechanism 2 is provided, the front end side can be compared with the case where the intermediate oil separation mechanism 16 is not provided. It is possible to suppress the refrigeration oil accompanying the refrigerant discharged from the compression element 2c from flowing into the intermediate cooler 7, thereby preventing the refrigeration oil from gathering into the intermediate cooler 7, thereby depleting the oil of the compression mechanism 2. You can stop it.

In addition, when the intermediate oil separation mechanism 16 is not provided, a decrease in heat transfer performance of the intermediate cooler 7 occurs due to the gathering of the refrigeration oil to the intermediate cooler 7. Since the amount of exchange heat (that is, the enthalpy difference between the points B1 and C1 in FIG. 2) becomes small, there is a fear that the heat dissipation loss in the heat source side heat exchanger 4 may not become small, and the intermediate cooler 7 By gathering the refrigeration oil in the furnace, the pressure loss of the intermediate cooler 7 increases, and the pressure of the refrigerant sucked into the compression element 2d on the rear end side (that is, the point C1 in FIG. 2) is lowered, Although the power consumption of the compression element 2d may increase, since the intermediate oil separation mechanism 16 is provided, the heat transfer performance of the intermediate cooler 7 due to the gathering of the refrigeration oil to the intermediate cooler 7 is reduced. I prevent the increase of one pressure loss, and the performance of the air conditioner 1 Can be improved.

Furthermore, the intermediate oil separation mechanism 16 in the present embodiment includes an intermediate oil separator 16a for separating refrigerant oil accompanying the refrigerant discharged from the compression element 2c on the front end side from the refrigerant, and the intermediate oil separator. Since the intermediate oil return pipe 16b connected to the 16a and the refrigerant oil separated from the refrigerant is returned to the compression mechanism 2, the intermediate oil separator 16a is connected to the compression element 2c on the front end side. By providing in the vicinity, it is possible to separate the refrigeration oil from the refrigerant in the vicinity of the compression element 2c on the front end side, whereby not only the intermediate cooler 7 but also the refrigeration oil in the intermediate refrigerant pipe 8 You can also stop gathering.

In addition, as the compressor 21 which comprises the compression mechanism 2, the low pressure dome type | mold which the refrigerant | coolant sucked by the compression element 2c of the front end side fills the space where the refrigeration oil in the casing 21a collects, and the casing 21a where the refrigeration oil collects. ) Is a medium pressure dome type in which the refrigerant discharged from the compression element 2c on the front side is filled, and a high pressure dome type in which the refrigerant discharged from the compression element 2c on the rear end is filled in the space in the casing 21a where the refrigeration oil is collected. Even if any one of them is employed, by providing the intermediate oil separation mechanism 16, the effect of preventing oil depletion of the compression mechanism 2 can be obtained, but in particular, the compression mechanism 2 When the high pressure dome-type compressor is used as the compressor 21, the refrigerant discharged from the compression element 2d on the rear end side is discharged to the space in the casing 21a where the refrigeration oil is collected, and then discharged out of the casing 21a. Since the amount of the refrigerant oil accompanying the refrigerant is not large, the refrigerant discharged from the compression element 2c on the front end side is directly discharged out of the casing 21a, so that the amount of the refrigerant oil accompanying the refrigerant is large. Since there is a high possibility that the amount of the refrigeration oil gathered in the intermediate | middle cooler 7 will increase, it is very effective to provide the intermediate oil separation mechanism 16.

(3) Modification Example 1

In the above embodiment, the intermediate oil separation mechanism 16 is constituted by the intermediate oil separator 16a and the intermediate oil return tube 16b. However, as shown in FIG. The intermediate oil return pipe 16b may be connected to the lower end of the header 16d provided at the inlet of the intermediate cooler 7. Here, the header 16d is a pipe member interposed between the intermediate refrigerant pipe 8 and the branch pipe for branching to each heat transfer flow path when the intermediate cooler 7 has a plurality of heat transfer flow paths. to be. In addition, the intermediate oil return tube 16b in the above-mentioned embodiment is connected except that the intermediate oil return tube 16b is connected to the lower end of the header 16d instead of the oil outlet of the intermediate oil separator 16a. ) Is the same configuration.

And in the structure of this modified example 1, since the header 16d provided in the inlet of the intermediate | middle cooler 7 functions as an oil separator, increase of an apparatus score can be suppressed compared with the above-mentioned embodiment.

In addition, in the modification mentioned later, although having the intermediate oil separator 16a and the intermediate oil return pipe 16b as an intermediate oil separation mechanism 16, it demonstrates as an example, Like the present modified example, the intermediate cooler 7 The structure in which the intermediate oil return tube 16b is connected to the lower end of the header 16d provided at the inlet may be adopted.

(4) Modification 2

In the above-described embodiment and its modification, the compressor 21 of one uniaxial two-stage compression structure as the compression mechanism 2 discharges from the compression element on the front side of the two compression elements 2c and 2d. The two stage compression type compression mechanism 2 which sequentially compresses the refrigerant into the compression element on the rear end side is configured, but two compressors of the single stage compression structure in which one compression element is rotationally driven by one compressor drive motor are provided. By connecting in series, the compression mechanism 2 of the two-stage compression structure may be comprised.

For example, as shown in FIG. 5, in the above-described embodiment, two compressors 22 in which the compression element 2c is accommodated and two compressors 23 in which the compression element 2d is connected are connected in series. The intermediate oil separation mechanism 16 which constitutes the compression mechanism 2 and has the intermediate oil separation mechanism 16 (that is, the intermediate oil separator 16a and the intermediate oil return pipe 16b) similar to the above-described embodiment. ) May be provided at a portion between the compression element 2c (that is, the compressor 22) and the inlet of the intermediate cooler 7 on the front end side of the intermediate refrigerant pipe 8. Here, the compression mechanism 2 has the compressor 22 and the compressor 23. The compressor 22 has the hermetic structure in which the compressor drive motor 22b, the drive shaft 22c, and the compression element 2c were accommodated in the casing 22a. And the compressor drive motor 22b is connected to the drive shaft 22c, and the drive shaft 22c is connected to the compression element 2c. In addition, the compressor 23 has a hermetic structure in which the compressor drive motor 23b, the drive shaft 23c, and the compression element 2d are housed in the casing 23a. And the compressor drive motor 23b is connected to the drive shaft 23c, and the drive shaft 23c is connected to the compression element 2d. The compression mechanism 2 sucks the coolant from the suction pipe 2a and compresses the sucked coolant by the compression element 2c, similarly to the above-described embodiment and its modifications. ), The refrigerant discharged into the intermediate refrigerant pipe (8) is sucked into the compression element (2d) to further compress the refrigerant, and then discharged into the discharge pipe (2b).

And also in the structure of this modified example 2, since the refrigeration oil accompanying the refrigerant | coolant discharged | emitted from the compression element 2c of the front end side accommodated in the compressor 22 can be suppressed from flowing into the intermediate | middle cooler 7, The gathering of the refrigeration oil to the cooler 7 can be prevented, and the oil depletion of the compression mechanism 2 can be prevented. Moreover, the fall of the heat transfer performance of the intermediate | middle cooler 7 and the increase of a pressure loss by the gathering of the refrigeration oil to the intermediate | middle cooler 7, can be prevented, and the performance of the air conditioner 1 can be improved.

(5) Modification 3

In the above-described embodiment and its modifications, the two-stage compression mechanism 2 that sequentially compresses the refrigerant discharged from the compression element on the front side of the two compression elements 2c and 2d into the compression element on the rear end side. However, among the three compression elements, a three-stage compression type compression mechanism 102 for sequentially compressing the refrigerant discharged from the compression element on the front side into the compression element on the rear side may be employed.

For example, as shown in FIG. 6, in the above-described embodiment, two compressors 24 in which the compression element 102c is accommodated, and two compressors 25 in which the compression elements 102d and 102e are accommodated in series. The intermediate oil separation mechanism having the intermediate oil separation mechanism 16 (i.e., the intermediate oil separator 16a and the intermediate oil return pipe 16b) similar to the above-described embodiment. (16) is a portion between the compression element 102c on the front side of the intermediate refrigerant pipe 8 (connecting the compression element 102c and the compression element 102d) and the inlet of the intermediate cooler 7, And a structure provided at a portion between the compression element 102d on the front end side of the intermediate refrigerant pipe 8 (connecting the compression element 102d and the compression element 102e) and the inlet of the intermediate cooler 7. You can do Here, the compression mechanism 102 is comprised by the compressor 24 which single-stage-compresses refrigerant | coolant with one compression element, and the compressor 25 which two-stage-compresses refrigerant | coolant with two compression elements is connected in series. . The compressor 24 is similar to the compressors 22 and 23 of the single stage compression structure in the modification 3 mentioned above, and the compressor drive motor 24b, the drive shaft 24c, and the compression element 102c are contained in the casing 24a. ) Is a sealed structure housed. The compressor drive motor 24b is connected to the drive shaft 24c, and the drive shaft 24c is connected to the compression element 102c. In addition, the compressor 25 has a compressor drive motor 25c, a drive shaft 25c, and a compression element 102d in the casing 25a, similarly to the compressor 21 having a two-stage compression structure in the above-described embodiment. , 102e) has a sealed structure. And the compressor drive motor 25b is connected to the drive shaft 25c, and this drive shaft 25c is connected to the two compression elements 102d and 102e. Then, the compressor 24 sucks the refrigerant from the suction pipe 102a, compresses the sucked refrigerant by the compression element 102c, and then compresses the compression element 102d connected to the rear end side of the compression element 102c. Is discharged to the intermediate refrigerant pipe (8) for suction. Then, the compressor 25 sucks the refrigerant discharged into the intermediate refrigerant pipe 8 into the compression element 102d to further compress the refrigerant, and then the compression element 102e connected to the rear end side of the compression element 102d. Discharged into the intermediate refrigerant pipe 8 for suctioning into the medium, and the refrigerant discharged into the intermediate refrigerant pipe 8 is sucked into the compression element 102e to further compress the refrigerant, and then discharged into the discharge pipe 102b. Consists of.

In addition, instead of the structure shown in FIG. 6 (that is, the structure in which the compressor 24 of a single stage compression type | mold and the compressor 25 of a two stage compression type | mold were connected in series), as shown in FIG. The compression compressor 26 and the single stage compression compressor 27 may be connected in series. Also in this case, since the compressor 26 has the compression elements 102c and 102d, and the compressor 27 has the compression element 102e, the three compression elements 102c are similar to the structure shown in FIG. , 102d and 102e can be obtained in series connection. In addition, the compressor 26 is the structure similar to the compressor 21 in the above-mentioned embodiment, and the compressor 27 is the structure similar to the compressors 22 and 23 in the modification 3 mentioned above. For this reason, the code | symbol which shows each part except the compression element 102c, 102d, 102e is changed into 26th or 27th, respectively, and description is abbreviate | omitted here.

Furthermore, instead of the structure shown in FIG. 6 (that is, the structure in which the single stage compression compressor 25 and the two stage compression compressor 24 are connected in series), as shown in FIG. The single stage compression compressors 24, 28 and 27 may be connected in series. Also in this case, since the compressor 24 has the compression element 102c, the compressor 28 has the compression element 102d, and the compressor 27 has the compression element 102e, either FIG. 6 or FIG. Similarly to the configuration shown in Fig. 7, a configuration in which three compression elements 102c, 102d and 102e are connected in series can be obtained. In addition, since the compressors 24 and 28 have the same structure as the compressors 22 and 23 in the above-mentioned modification 3, the code | symbol which shows each part except the compression elements 102c and 102d is 24, respectively. It is assumed that it is replaced with No. 28 and the description is omitted here.

Thus, in this modification, the compression mechanism 102 has three compression elements 102c, 102d, and 102e, and is discharged from the compression element of the front side among these compression elements 102c, 102d, and 102e. It is configured to sequentially compress the refrigerant into the compression element on the rear end side. And the refrigerant circuit 110 in this modification is comprised from the compression mechanism 102, the intermediate refrigerant pipe 8, the intermediate | middle cooler 7, the intermediate oil separation mechanism 16, etc. As shown in FIG.

Next, operation | movement of the air conditioner 1 of this modification is demonstrated using FIGS. 6-10. Here, FIG. 9 is a pressure enthalpy diagram which shows the refrigeration cycle at the time of cooling operation in modified example 3, and FIG. 10 is a temperature entropy diagram which shows the refrigeration cycle at the time of cooling operation in modified example 3. FIG. In addition, the operation control in the following cooling operation is performed by the above-mentioned control part (not shown). In addition, in the following description, "high pressure" means the high pressure (that is, the pressure in points D, D ', E of FIG. 9, 10) in a refrigeration cycle, and "low pressure" means a refrigeration cycle. Low pressure (ie, pressure at points A and F in FIGS. 9 and 10), and "medium pressure" means intermediate pressure (ie, points B1 and B2 in FIGS. 9 and 10) in a refrigeration cycle. , Pressure at B2 ', C1, C2, and C2').

When the compression mechanism 102 is driven, the low pressure refrigerant (see point A in FIGS. 6 to 10) is sucked into the compression mechanism 102 from the suction pipe 102a and, first, the intermediate pressure by the compression element 102c. After compressed to, the discharged refrigerant from the compression element 102c on the front side is discharged to the intermediate refrigerant pipe 8 for suctioning into the compression element 102d on the rear end side (see point B1 in FIGS. 6 to 10). . The medium pressure refrigerant discharged from the compression element 102c on the front side is separated from the intermediate oil provided at the portion between the compression element 102c on the front side of the intermediate refrigerant pipe 8 and the inlet of the intermediate cooler 7. It flows into the intermediate oil separator 16a which comprises the mechanism 16, and is sent to the intermediate cooler 7 after the accompanying refrigeration oil is isolate | separated. In addition, the refrigerant oil separated from the medium pressure refrigerant in the intermediate oil separator 16a flows into the intermediate oil return tube 16b constituting the intermediate oil separation mechanism 16, and the intermediate oil return tube 16b. After the pressure is reduced by the pressure reduction mechanism 16c provided in the chamber, the pressure is returned to the compression mechanism 102 (here, the suction pipe 102a), and is again sucked by the compression mechanism 102. Next, the medium pressure refrigerant after the refrigerator oil is separated in the intermediate oil separation mechanism 16 is cooled by performing heat exchange with water or air as a cooling source in the intermediate cooler 7 (FIGS. 6 to 10). See point C1). The refrigerant cooled in this intermediate cooler (7) is then sucked into a compression element (102d) connected to the rear end side of the compression element (102c) and compressed to a higher intermediate pressure, after which the compression element ( The refrigerant discharged from 102d is discharged to the intermediate refrigerant pipe 8 for suctioning into the compression element 102e on the rear end side (see point B2 in Figs. 6 to 10). The medium pressure refrigerant discharged from the compression element 102d at the front end is separated from the intermediate oil provided at a portion between the compression element 102d at the front end of the intermediate coolant tube 8 and the inlet of the intermediate cooler 7. It flows into the intermediate oil separator 16a which comprises the mechanism 16, and is sent to the intermediate cooler 7 after the accompanying refrigeration oil is isolate | separated. In addition, the refrigerant oil separated from the medium pressure refrigerant in the intermediate oil separator 16a flows into the intermediate oil return tube 16b constituting the intermediate oil separation mechanism 16, and the intermediate oil return tube 16b. After the pressure is reduced by the pressure reduction mechanism 16c provided in the chamber, the pressure is returned to the suction pipe 102a of the compression mechanism 2, and is again sucked by the compression mechanism 102. Next, the medium pressure refrigerant after the refrigerator oil is separated in the intermediate oil separation mechanism 16 is cooled by performing heat exchange with water or air as a cooling source in the intermediate cooler 7 (FIGS. 6 to 10). See point C2). The refrigerant cooled in this intermediate cooler 7 is then sucked into the compression element 102e connected to the rear end side of the compression element 102d and further compressed, and discharged from the compression mechanism 102 to the discharge tube 102b. (See point D in Figs. 6 to 10). Here, the high-pressure refrigerant discharged from the compression mechanism 102 is subjected to the three-stage compression operation by the compression elements 102c, 102d, and 102e, so that the threshold pressure (that is, the threshold pressure Pcp at the critical point CP shown in Fig. 9) is reached. Compressed to pressure over). And the high pressure refrigerant | coolant discharged from this compression mechanism 102 flows into the oil separator 41a which comprises the oil separation mechanism 41, and the accompanying refrigerator oil is isolate | separated. In addition, the refrigeration oil separated from the high pressure refrigerant in the oil separator 41a flows into the oil return pipe 41b constituting the oil separation mechanism 41 and is provided with a pressure reducing mechanism 41c provided in the oil return pipe 41b. ), The pressure is returned to the compression mechanism 102 (here, the suction pipe 102a), and is again sucked into the compression mechanism 102. Next, the high pressure refrigerant after the refrigeration oil is separated in the oil separation mechanism 41 is sent to the heat source side heat exchanger 4 which functions as a cooler of the refrigerant via the check mechanism 42. Then, the high-pressure refrigerant sent to the heat source side heat exchanger 4 is cooled by performing heat exchange with water or air as a cooling source in the heat source side heat exchanger 4 (see point E in FIGS. 6 to 10). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 is reduced in pressure by the expansion mechanism 5 to become a refrigerant in a low gas-liquid abnormal state, and the use-side heat exchanger 6 functioning as a heater of the refrigerant. (See point F in Figs. 6-10). And the refrigerant | coolant of the low-pressure gas-liquid abnormality state sent to the utilization side heat exchanger 6 heats and evaporates with water or air as a heating source in the utilization side heat exchanger 6, and it evaporates (FIGS. See point A in FIG. 10). The low pressure refrigerant heated in the use-side heat exchanger 6 is again sucked into the compression mechanism 102. In this manner, cooling operation is performed.

Thus, in the structure of this modification, the intermediate | middle cooler 7 is provided in the intermediate refrigerant pipe 8 for sucking in the refrigerant | coolant discharged from the compression element 102c by the compression element 102d, and the compression element ( Since the intermediate cooler 7 is provided in the intermediate refrigerant pipe 8 for sucking the refrigerant discharged from 102d into the compression element 102e, the intermediate cooler 7 is not provided (in this case, FIG. 9, FIG. 10, the rear end side of the compression element 102c as compared to the point A to point B1 to point B2 '(C2') to point D 'to point E to point F). The temperature of the refrigerant sucked into the compression element 102d of and the temperature of the refrigerant sucked into the compression element 102e on the rear end side of the compression element 102d are lowered (points B1, C1, B2, and C2 in Fig. 10). The temperature of the refrigerant discharged from the compression element 102e is also lowered (see points D and D 'in FIG. 10). For this reason, in the structure of this modification, in the heat source side heat exchanger 4 which functions as a cooler of a high pressure refrigerant | coolant, compared with the case where the intermediate | middle cooler 7 is not provided, water, air as a cooling source, and a refrigerant | coolant are not provided. It is possible to reduce the temperature difference and to reduce the heat dissipation loss corresponding to the area enclosed by the points B1, B2 '(C2'), D ', D, C2, B2, and C1 in FIG. From this, the driving efficiency can be improved. In addition, since this area is larger than the area in the two-stage compression type refrigeration cycle as in the above-described embodiment and its modifications, the operation efficiency can be further improved as compared with the above-described embodiment and its modifications. .

In addition, in the structure of this modification, the refrigerant | coolant discharged from the compression element 102c of a front side to the part between the compression element 102c of the front side of the intermediate | middle refrigerant pipe 8, and the inlet of the intermediate | middle cooler 7 is carried out. Is provided with an intermediate oil separation mechanism 16 which separates the refrigeration oil accompanying the refrigerant from the refrigerant and returns it to the suction side of the compression mechanism 2, and furthermore, the compression element 102d on the front end side of the intermediate refrigerant pipe 8 and the intermediate portion. Intermediate oil separation mechanism 16 for separating the refrigerant oil accompanying the refrigerant discharged from the compression element 102d on the front end side from the refrigerant and returning it to the suction side of the compression mechanism 2 at a portion between the inlets of the cooler 7. ), The oil depletion of the compression mechanism 102 can be prevented in the same manner as in the above-described embodiments and modifications thereof.

In addition, when the intermediate oil separation mechanism 16 is not provided, a decrease in heat transfer performance of the intermediate cooler 7 occurs due to the gathering of the refrigeration oil to the intermediate cooler 7. Since the amount of exchange heat (that is, the enthalpy difference between the points B1 and C1 in FIG. 9 and the enthalpy difference between the points B2 and C2 in FIG. 9) becomes small, there is a fear that the heat radiation loss in the heat source side heat exchanger 4 will not become small. In addition, by the gathering of the refrigeration oil to the intermediate cooler 7, the pressure loss of the intermediate cooler 7 increases, and the pressure of the refrigerant sucked into the compression element 102d or the compression element 102e on the rear end side. (I.e., the point C1 and the point C2 in Fig. 9) are lowered, and the power consumption of the compression element 102d and the compression element 102e on the rear end side may increase, but the intermediate oil separation mechanism 16 is provided. Therefore, similarly to the above-described embodiment and its modification, the air conditioner 1 It can improve performance.

In addition, as the two-stage compression type compressor 25 (refer to FIG. 6) which comprises the compression mechanism 102, the refrigerant | coolant suctioned by the compression element 102d of the front end side in the space where the refrigeration oil in the casings 25a and 25a collect | collects The compression element on the rear end side in the space in the casing 25a in which the refrigerant discharged from the compression element 102d on the front side is filled in the space in the casing 25a in which the refrigerating oil is filled with the low pressure dome type. Even if any one of the high-pressure dome type filled with the refrigerant discharged from 102e is employed, by providing the intermediate oil separation mechanism 16, the effect of preventing oil depletion of the compression mechanism 102 can be obtained. In particular, when a high pressure dome type compressor is employed as the compressor 25 constituting the compression mechanism 102, the refrigerant discharged from the compression element 102e on the rear end side enters the space in the casing 25a where the refrigeration oil is collected. Work However, since after being discharged, it is discharged out of the casing 25a, and while the amount of the refrigeration oil accompanying the refrigerant is not large, the refrigerant discharged from the compression element 102d on the front end side is discharged directly out of the casing 25a. Since the amount of the refrigeration oil which accompanies a refrigerant | coolant is large, and there exists a high possibility that the quantity of the refrigeration oil which collects in the intermediate | middle cooler 7 will increase, it is very effective to provide the intermediate oil separation mechanism 16. In addition, also in the case of employing a high pressure dome type in the two stage compression compressor 26 constituting the compression mechanism 102, the intermediate oil separation mechanism 16 is provided in the same manner as in the compressor 25. It is very valid to do.

In addition, although detailed description is abbreviate | omitted here, instead of the three-stage compression type compression mechanism 102, you may employ | adopt a multistage compression mechanism rather than three-stage compression type, such as four-stage compression type, In this case, also in this case, The effect similar to a modification can be acquired.

(6) Modification 4

In the above-described embodiment and its modifications, the multi-stage compression mechanism 2 and the compression mechanism 102 that are sequentially compressed by a plurality of compression elements are configured to have only one system. In the case where the large use side heat exchanger 6 is connected, or the plurality of use side heat exchangers 6 are connected, etc., the multistage compression type compression mechanism 2 and the compression mechanism 102 are connected in parallel in multiple systems. A parallel multistage compression type compression mechanism may be employed.

For example, as shown in FIG. 11, the first compression mechanism 203 of the two stage compression type having the compression elements 203c and 203d and the two stage compression type having the compression elements 204c and 204d are provided. It can be set as the refrigerant circuit 210 which employ | adopted the compression mechanism 202 which has the structure which connected 2 compression mechanisms 204 in parallel.

In the present modification, the first compression mechanism 203 is composed of a compressor 29 which compresses the refrigerant in two stages by two compression elements 203c and 203d, and the suction capillary of the compression mechanism 202 is provided. It is connected to the 1st suction branch pipe 203a branched from the pipe 202a, and the 1st discharge branch pipe 203b which joins the discharge mother pipe 202b of the compression mechanism 202. As shown in FIG. In the present modification, the second compression mechanism 204 is constituted by a compressor 30 that compresses the refrigerant in two stages by two compression elements 204c and 204d, and the suction capillary 202a of the compression mechanism 202 is provided. ) Is connected to the second suction branch pipe 204a and the second discharge branch pipe 204b joining the discharge mother pipe 202b of the compression mechanism 202. In addition, since the compressors 29 and 30 are the same structure as the compressor 21 in the above-mentioned embodiment, the code | symbol which shows each part except the compression elements 203c, 203d, 204c, 204d is 29, respectively. I will replace it with No. 30, and a description is omitted here. Then, the compressor 29 sucks the refrigerant from the first suction branch pipe 203b, compresses the sucked refrigerant by the compression element 203c, and then forms the intermediate refrigerant pipe 8 in the middle of the first inlet side. The compressed element discharged to the branch pipe (81) and the refrigerant discharged to the first inlet side intermediate branch pipe (81) through the intermediate mother pipe (82) and the first outlet side intermediate branch pipe (83) constituting the intermediate refrigerant pipe (8). It is configured to discharge to the first discharge branch pipe 203b after suctioning at 203d to further compress the refrigerant. The compressor 30 sucks the refrigerant from the first suction branch pipe 204b, compresses the sucked refrigerant by the compression element 204c, and then configures the second inlet side intermediate branch pipe constituting the intermediate refrigerant pipe 8 ( 84, and the refrigerant discharged to the second inlet side intermediate pipe 84 through the intermediate capillary 82 and the second outlet side intermediate pipe 85 constituting the intermediate refrigerant pipe 8 (204d) ), And further compresses the refrigerant, and then discharges it to the second discharge branch pipe (204b). The intermediate refrigerant pipe 8 is the rear end side of the compression elements 203c and 204c for the refrigerant discharged from the compression elements 203c and 204c connected to the front side of the compression elements 203d and 204d in this modification. A first inlet-side intermediate branch pipe 81 which is a refrigerant pipe for suctioning into the compression elements 203d and 204d connected to the first side, and is mainly connected to the discharge side of the compression element 203c on the front end side of the first compression mechanism 203. ), An intermediate portion where the second inlet side intermediate branch pipes 84 and the two inlet side intermediate branch pipes 81 and 84 joined to the discharge side of the compression element 204c on the front end side of the second compression mechanism 204 join. A first outlet-side intermediate branch pipe 83 branched from the mother pipe 82, the intermediate mother pipe 82, and connected to the suction side of the compression element 203d on the rear end side of the first compression mechanism 203, and the intermediate mother pipe ( It has a 2nd outlet side intermediate branch pipe 85 branched from 82 and connected to the suction side of the compression element 204d of the rear end side of the 2nd compression mechanism 204. As shown in FIG. In addition, the discharge capillary 202b is a refrigerant pipe for sending the refrigerant discharged from the compression mechanism 202 to the heat source side heat exchanger 4, and is provided in the first discharge branch pipe 203b connected to the discharge capillary 202b. The 1st oil separation mechanism 241 and the 1st check mechanism 242 are provided, The 2nd oil separation mechanism 243 and the 2nd check finger are attached to the 2nd discharge branch pipe 204b connected to the discharge mother pipe 202b. The mechanism 244 is provided. The first oil separation mechanism 241 is a mechanism for separating the refrigerant oil accompanying the refrigerant discharged from the first compression mechanism 203 from the refrigerant and returning it to the suction side of the compression mechanism 202, and mainly, the first compression mechanism. The first oil separator 241a which separates the refrigerant oil accompanying the refrigerant discharged from the refrigerant 203 from the refrigerant, and the refrigerant oil which is connected to the first oil separator 241a and separated from the refrigerant are supplied to the compression mechanism 202. It has the 1st oil return pipe | tube 241b which returns to a suction side. The second oil separation mechanism 243 is a mechanism for separating the refrigeration oil accompanying the refrigerant discharged from the second compression mechanism 204 from the refrigerant and returning it to the suction side of the compression mechanism 202. The second oil separator 243a which separates the refrigerant oil accompanying the refrigerant discharged from the 204 from the refrigerant, and the refrigerant oil which is connected to the second oil separator 243a and separated from the refrigerant are separated from the compression mechanism 202. It has the 2nd oil return pipe | tube 243b which returns to a suction side. In this modification, the 1st oil return pipe 241b is connected to the 2nd suction branch pipe 204a, and the 2nd oil return pipe 243c is connected to the 1st suction branch pipe 203a. For this reason, the refrigeration oil accompanying the refrigerant discharged from the first compression mechanism 203 due to the bias between the amount of the refrigerant oil collected in the first compression mechanism 203 and the amount of the refrigerant oil collected in the second compression mechanism 204. Even when a bias is generated between the amount and the amount of the refrigerant oil accompanying the refrigerant discharged from the second compression mechanism 204, the refrigerant oil returns a lot to the lesser amount of the refrigerant oil among the compression mechanisms 203 and 204, The bias between the amount of the refrigeration oil collected in the compression mechanism 203 and the amount of the refrigeration oil collected in the second compression mechanism 204 is eliminated. In addition, in this modification, the part of the 1st suction branch pipe 203a from the confluence part with the 2nd oil return pipe 243b to the confluence part with the suction capillary 202a is the suction capillary 202a. ), And the second suction branch pipe 204a is formed from the confluence with the first oil return pipe 241b to the confluence with the suction capillary 202a. It is comprised so that the part in between may become the gradient which goes down toward the confluence part with the suction capillary 202a. Therefore, even if either one of the compression mechanisms 203 and 204 is stopped, the refrigeration oil returned from the oil return pipe corresponding to the compression mechanism during operation to the suction branch pipe corresponding to the compression mechanism at the stop is the suction capillary tube. Returning to 202a, oil depletion of the compression mechanism during operation is less likely to occur. The oil return pipes 241b and 243b are provided with pressure reduction mechanisms 241c and 243c for depressurizing the refrigeration oil flowing through the oil return pipes 241b and 243b. The check mechanisms 242 and 244 allow the flow of the refrigerant from the discharge side of the compression mechanisms 203 and 204 to the heat source side heat exchanger 4, and further, from the heat source side heat exchanger 4, to the compression mechanism 203. 204 is a mechanism for interrupting the flow of the refrigerant to the discharge side.

Thus, in this modification, the compression mechanism 202 has two compression elements 203c and 203d, and the refrigerant | coolant discharged from the compression element of the front side among these compression elements 203c and 203d is the rear end side. And a first compression mechanism 203 configured to sequentially compress the compression element of the first and second compression elements 204c and 204d together with the refrigerant discharged from the compression element on the front side of these compression elements 204c and 204d. The second compression mechanism 204 configured to sequentially compress the compression element on the side is connected in parallel.

The intermediate | middle cooler 7 is provided in the intermediate mother pipe 82 which comprises the intermediate refrigerant pipe 8 in this modification, and discharges from the compression element 203c of the front end side of the 1st compression mechanism 203. And a refrigerant discharged from the compression element 204c on the front end side of the second compression mechanism 204. In other words, the intermediate cooler 7 functions as a cooler common to the two compression mechanisms 203 and 204. For this reason, the circuit around the compression mechanism 202 at the time of installing the intermediate | middle cooler 7 with respect to the parallel multistage compression type compression mechanism 202 which connected the multistage compression type compression mechanism 203, 204 in multiple systems parallel. The configuration can be simplified.

In addition, in this modification, the intermediate | middle oil separation mechanism 16 is a joining part with the inlet side intermediate branch pipes 81 and 84 of the intermediate mother pipe 82 which comprises the intermediate refrigerant pipe 8, and the intermediate | middle cooler ( It is provided in the part between the inlets of 7), and is provided in common in the two compression mechanisms 203 and 204 similarly to the intermediate | middle cooler 7. As shown in FIG. In the present modification, the intermediate oil return pipe 16b connects between the oil outlet of the intermediate oil separator 16a and the suction capillary 202a of the compression mechanism 202.

The first inlet-side intermediate branch pipe 81 constituting the intermediate refrigerant pipe 8 has a refrigerant from the discharge side of the compression element 203c on the front end side of the first compression mechanism 203 to the intermediate mother pipe 82 side. And a check mechanism 81a is provided to allow the flow of the refrigerant and to block the flow of the refrigerant from the intermediate mother pipe 82 side to the discharge side of the compression element 203c on the front end side, and the intermediate refrigerant pipe 8 is provided. The second inlet-side intermediate branch pipe 84 constituting the above allows the flow of the refrigerant from the discharge side of the compression element 204c on the front end side of the second compression mechanism 203 to the intermediate mother tube 82 side, A check mechanism 84a is provided to block the flow of the refrigerant from the intermediate mother pipe 82 side to the discharge side of the compression element 204c on the front end side. In this modification, check valves are used as check mechanisms 81a and 84a. For this reason, even when either one of the compression mechanisms 203 and 204 is stopped, the refrigerant discharged from the compression element on the front side of the compression mechanism during operation, through the intermediate refrigerant pipe 8, Since it does not occur to reach the discharge side of the compression element, the refrigerant discharged from the compression element on the front side of the compression mechanism during operation is transferred to the suction side of the compression mechanism 202 through the compression element on the front side of the compression mechanism during the stop. The freezing of the refrigeration oil of the compression mechanism during the stoppage is prevented from occurring. As a result, the shortage of the refrigeration oil at the time of starting the compression mechanism during the stoppage is less likely to occur. In addition, when the priority of operation is provided between the compression mechanisms 203 and 204 (for example, when it is set as the compression mechanism which drives the 1st compression mechanism 203 preferentially), the compression during the above-mentioned stoppage is carried out. Since the thing corresponding to a mechanism is limited to the 2nd compression mechanism 204, in this case, only the check mechanism 84a corresponding to the 2nd compression mechanism 204 may be provided.

As described above, when the first compression mechanism 203 is used as a compression mechanism that preferentially operates, since the intermediate refrigerant pipe 8 is provided in common in the compression mechanisms 203 and 204, it is in operation. Refrigerant discharged from the compression element 203c on the front end side corresponding to the first compression mechanism 203 passes through the second outlet side intermediate branch pipe 85 of the intermediate refrigerant pipe 8 while the second compression mechanism 204 is stopped. The refrigerant discharged from the compression element 203c on the front end side of the first compression mechanism 203 during operation, thereby reaching the suction side of the compression element 204d on the rear end side). The refrigeration oil of the 2nd compression mechanism 204 which is stopped, flows out into the discharge side of the compression mechanism 202 through the inside of the compression element 204d of the rear end side of 204, and starts the 2nd compression mechanism 204 during suspension. There is a fear that a shortage of refrigeration oil occurs. So, in this modification, when the opening-closing valve 85a is provided in the 2nd outlet side intermediate branch pipe 85, and the 2nd compression mechanism 204 is stopping, this opening-and-closing valve 85a will make a 2nd outlet. The flow of the refrigerant in the side intermediate branch pipe 85 is blocked. As a result, the refrigerant discharged from the compression element 203c on the front end side of the first compression mechanism 203 during operation is passed through the second outlet side intermediate branch pipe 85 of the intermediate refrigerant pipe 8 while the second stationary device is stopped. Since nothing reaches the suction side of the compression element 204d on the rear end side of the compression mechanism 204, the refrigerant discharged from the compression element 203c on the front side of the first compression mechanism 203 during operation is stopped. The refrigeration oil of the 2nd compression mechanism 204 which stops falls out to the discharge side of the compression mechanism 202 through the compression element 204d of the rear end side of the 2nd compression mechanism 204, and it does not arise, As a result, the shortage of the refrigeration oil at the time of starting the second compression mechanism 204 while stopping becomes less likely to occur. In addition, in this modification, the solenoid valve is used as the opening-closing valve 85a.

In addition, when setting it as the compression mechanism which drives the 1st compression mechanism 203 preferentially, the 2nd compression mechanism 204 will be started after starting the 1st compression mechanism 203, but at this time, Since the intermediate refrigerant pipe 8 is provided in common in the compression mechanisms 203 and 204, the pressure on the discharge side of the compression element 203c on the front end side of the second compression mechanism 204 and the compression element on the rear end side ( The pressure on the suction side of 203d is started from a state in which the pressure on the suction side of the compression element 203c on the front side and the pressure on the discharge side of the compression element 203d on the rear end side are higher than the pressure, so that the second compression mechanism is stable. It is difficult to maneuver 204. So, in this modification, the starting bypass pipe 86 which connects the discharge side of the compression element 204c of the front side of the 2nd compression mechanism 204, and the suction side of the compression element 204d of the rear end side is 86 ), An on-off valve 86a is provided in the start bypass pipe 86, and when the second compression mechanism 204 is stopped, the start bypass pipe is opened by the on / off valve 86a. When the flow of the refrigerant in the 86 is interrupted, and the flow of the refrigerant in the second outlet-side intermediate branch pipe 85 is interrupted by the opening / closing valve 85a, and the second compression mechanism 204 is started, The refrigerant | coolant discharged from the compression element 204c of the front end side of the 2nd compression mechanism 204 is made into the state which enables the refrigerant | coolant to flow in the starting bypass pipe 86 by the on-off valve 86a. Starting bar without joining the refrigerant discharged from the compression element 204c on the front end side of the mechanism 203. The suction element is sucked into the compression element 204d on the rear end side through the pass pipe 86 so that the operating state of the compression mechanism 202 is stable (for example, the suction pressure, the discharge pressure, and the intermediate pressure of the compression mechanism 202). When the pressure is stabilized), the refrigerant can flow into the second outlet side intermediate branch pipe 85 by the on / off valve 85a, and the start bypass pipe 86 is provided by the on / off valve 86a. By blocking the flow of the refrigerant inside, it is possible to shift to normal cooling operation. In addition, in this modification, the start bypass pipe 86 has the compression element of the opening-ended valve 85a of the 2nd outlet side middle branch pipe 85, and the rear end side of the 2nd compression mechanism 204 ( 204d) is connected between the suction side, the other end of the check mechanism 84a of the discharge side of the compression element 204c on the front end side of the second compression mechanism 204 and the second inlet side intermediate branch pipe 84. It is connected between them, and when starting the 2nd compression mechanism 204, it becomes possible to make it the state which is hard to be influenced by the intermediate pressure part of the 1st compression mechanism 203. In this modification, a solenoid valve is used as the on-off valve 86a.

In addition, the operation | movement at the time of the cooling operation of the air conditioner 1 of this modification is a slightly complicated circuit structure around the compression mechanism 202 by the compression mechanism 202 provided instead of the compression mechanism 2. Except for the point of change, the description is basically the same as that in the operation during the cooling operation in the above-described embodiment (FIGS. 1 to 3 and related descriptions).

And also in the structure of this modification 4, it accompanies the refrigerant | coolant discharged from the compression element 203c of the front end side of the 1st compression mechanism 203, and the compression element 204c of the front end side of the 2nd compression mechanism 204. Since refrigeration oil can be prevented from flowing into the intermediate | middle cooler 7, it can prevent collection of the refrigeration oil to the intermediate | middle cooler 7, and can prevent the oil depletion of the compression mechanism 202. Moreover, the fall of the heat transfer performance of the intermediate | middle cooler 7 and the increase of a pressure loss by the gathering of the refrigeration oil to the intermediate | middle cooler 7, can be prevented, and the performance of the air conditioner 1 can be improved. In addition, in the structure of this modification, although the parallel multistage compression type compression mechanism 202 which connected the multistage compression type compression mechanism 203, 204 in multiple system parallel connection is employ | adopted, the intermediate oil separation mechanism ( Since 16 is provided in common in the two compression mechanisms 203 and 204, the circuit structure around the compression mechanism 202 can be simplified. In addition, in this modification, since the intermediate oil return pipe 16b is connected between the oil outlet of the intermediate oil separator 16a and the suction capillary 202a of the compression mechanism 202, the compression mechanism 203, The refrigerator oil can be returned reliably with respect to both of 204.

In addition, although detailed description is abbreviate | omitted here, it replaces with the two-stage compression type compression mechanisms 203 and 204, and 2, such as a three-stage compression type (for example, the compression mechanism 102 in the modification 3), etc. A multistage compression mechanism may be employed than the single compression type, and a parallel multistage compression mechanism in which three or more compression mechanisms are connected in parallel may be employed. In this case, The effect similar to a modification can be acquired.

(7) Modification 5

In the modification 4 mentioned above, as shown in FIG. 11, although the intermediate oil separation mechanism 16 is provided in common with the two compression mechanisms 203 and 204, as shown in FIG. It may be provided so as to correspond to the compression mechanisms 203 and 204. For example, about the 1st compression mechanism 203, the intermediate oil separation mechanism 16 is provided in the 1st inlet side intermediate branch pipe 81 connected to the discharge side of the compression element 203c of the front end side, For the 2 compression mechanism 204, the intermediate oil separation mechanism 16 can be provided in the second inlet side intermediate branch pipe 84 connected to the discharge side of the compression element 204c on the front end side.

And also in the structure of this modification 5, the compression element 203c of the front end side of the 1st compression mechanism 203, and the compression element of the front end side of the 2nd compression mechanism 204 similarly to the modification 4 mentioned above ( Since refrigeration oil accompanying the refrigerant discharged from 204c can be suppressed from flowing into the intermediate | middle cooler 7, it can prevent collection of the refrigeration oil to the intermediate | middle cooler 7, and can prevent the exhaustion of the compression mechanism 202. . Moreover, the fall of the heat transfer performance of the intermediate | middle cooler 7 and the increase of a pressure loss by the gathering of the refrigeration oil to the intermediate | middle cooler 7, can be prevented, and the performance of the air conditioner 1 can be improved. Moreover, in the structure of this modification, since the intermediate oil separation mechanism 16 is provided so that it may correspond to each compression mechanism 203, 204, the intermediate oil separator 16a is provided with the compression element 203c, 204c of the front end side. By installing in the vicinity of the cooling medium, refrigeration oil can be separated from the refrigerant in the vicinity of the compression elements 203c and 204c on the front end side, whereby not only the intermediate cooler 7 but also the intermediate mother pipe 82 or the inlet. Gathering of the refrigeration oil in the intermediate refrigerant pipe 8 such as the side intermediate paper tubes 81 and 84 can also be prevented.

In addition, in the structure shown in FIG. 12, the intermediate oil return pipe 16b of the intermediate oil separation mechanism 16 provided corresponding to the 1st compression mechanism 203 is made into the suction capillary (of the 2nd suction branch pipe 204a). The intermediate oil return pipe 16b of the intermediate oil separation mechanism 16 provided in correspondence with the second compression mechanism 204 is connected to the portion configured to be a downward slope toward the confluence with the 202a, and the first suction branch pipe ( It may be connected to a portion configured to be a gradient descending toward the confluence of the suction capillary 202a of 203a (see FIG. 13).

In this configuration, in addition to the above-described effects, the first compression mechanism 203 is caused due to the bias between the amount of the refrigerant oil collected in the first compression mechanism 203 and the amount of the refrigerant oil collected in the second compression mechanism 204. Between the amount of refrigeration oil accompanying the refrigerant discharged from the compression element 203c on the front end side of the c) and the amount of the refrigeration oil accompanying the refrigerant discharged from the compression element 204c on the front side of the second compression mechanism 204. Even when bias occurs, much of the refrigeration oil is returned to the lesser amount of the refrigeration oil in the compression mechanisms 203 and 204, and the amount of the refrigerant oil collected in the first compression mechanism 203 and the freezer collected in the second compression mechanism 204 are reduced. The bias between the positive amounts can be eliminated. Furthermore, even when either one of the compression mechanisms 203 and 204 is stopped, the refrigeration oil returned from the intermediate oil return tube corresponding to the compression mechanism during operation to the suction branch pipe corresponding to the compression mechanism at the stop is the suction capillary 202a. This can make it difficult to produce oil depletion of the compression mechanism during operation.

(8) Modification 6

In the above-described embodiments and modifications thereof, in the air conditioner 1 configured to enable the cooling operation, the intermediate coolant tube 8 is provided with the intermediate cooler 7 installed in the intermediate coolant tube 8. By installing the intermediate oil separation mechanism 16 between the compression element on the front end side of the front end and the inlet of the intermediate cooler 8, the heat dissipation loss in the heat source side heat exchanger 4 functioning as the cooler of the refrigerant is reduced. In addition to improving the operating efficiency, it is possible to obtain the effect of preventing oil depletion of the compression mechanism during operation. In addition to this configuration, the cooling operation and the heating operation can be switched, and the heat source side heat exchanger (4) Alternatively, a rear end injection tube may be further provided for branching the cooled refrigerant to return to the compression element 2d on the rear end side.

For example, as shown in Fig. 14, in the above-described embodiment in which the two-stage compression type compression mechanism 2 is employed, the switching mechanism 3 for switching the cooling operation and the heating operation is provided. And instead of the expansion mechanism 5, the receiver inlet expansion mechanism 5a and the receiver outlet expansion mechanism 5b are provided, and the bridge circuit 17, the receiver 18, and the rear side injection pipe 19 are provided. And a refrigerant circuit 310 in which an economizer heat exchanger 20 is provided.

The switching mechanism 3 is a mechanism for changing the direction of the flow of the refrigerant in the refrigerant circuit 310, and during the cooling operation, the refrigerant that compresses the heat source side heat exchanger 4 by the compression mechanism 2. Of the discharge side of the compression mechanism 2 and the one end of the heat source side heat exchanger 4, in order to function as the cooler of the heat exchanger 6 and the use side heat exchanger 6 as a heater of the refrigerant cooled in the heat source side heat exchanger 4. And the suction side and the utilization side heat exchanger 6 of the compressor 21 are connected (refer to the solid line of the switching mechanism 3 in FIG. 14, hereinafter the state of the switching mechanism 3 is “cooled”. Operation state ”), during the heating operation, the use-side heat exchanger 6 is used as a cooler for the refrigerant compressed by the compression mechanism 2, and the heat-source side heat exchanger 4 is used for the use-side heat exchanger 6 In order to function as a heater of the cooled refrigerant in the It is possible to connect the suction side of the compression mechanism 2 and one end of the heat source side heat exchanger 4 together with connecting the side heat exchanger 6 (refer to the broken line of the switching mechanism 3 of FIG. 14 below). The state of this switching mechanism 3 is called "heating operation state." In the present embodiment, the switching mechanism 3 is connected to the suction side of the compression mechanism 2, the discharge side of the compression mechanism 2, the heat source side heat exchanger 4, and the use side heat exchanger 6 on all sides. It is a switching valve. In addition, the switching mechanism 3 is not limited to a four-way switching valve, For example, it is comprised so that it may have a function which changes the direction of the flow of refrigerant similar to the above by combining several solenoid valves. Anyway.

In this manner, the switching mechanism 3 includes a cooling operation state in which the refrigerant is circulated in the order of the compression mechanism 2, the heat source side heat exchanger 4, the expansion mechanisms 5a and 5b, and the use side heat exchanger 6. And the compression mechanism 2, the use-side heat exchanger 6, the expansion mechanisms 5a and 5b, and the heat source-side heat exchanger 4 in order to switch the heating operation state for circulating the refrigerant.

In addition, an intermediate cooler bypass pipe 9 is connected to the intermediate coolant pipe 8 so as to bypass the intermediate cooler 7. The intermediate cooler bypass pipe 9 functions as an intermediate cooling function limiting mechanism that restricts the flow rate of the refrigerant flowing through the intermediate cooler 7. The intermediate cooler bypass pipe 9 is provided with an intermediate cooler bypass opening / closing valve 11. The intermediate cooler bypass open / close valve 11 is a solenoid valve in this embodiment. The intermediate cooler bypass opening / closing valve 11 is closed when the switching mechanism 3 is in the cooling operation state, and control is opened when the switching mechanism 3 is in the heating operation state.

In addition, the intermediate refrigerant pipe 8 has a position on the intermediate cooler 7 side from the connection with the intermediate cooler bypass pipe 9 (that is, the intermediate cooler bypass pipe 9 on the inlet side of the intermediate cooler 7). The cooler opening / closing valve 12 is provided in the part from the connection part to the connection part of the outlet side of the intermediate | middle cooler 7). The cooler opening / closing valve 12 functions as an intermediate cooling function limiting mechanism that restricts the flow rate of the refrigerant flowing through the intermediate cooler 7. The cooler open / close valve 12 is a solenoid valve in this embodiment. The cooler opening / closing valve 12 is opened when the switching mechanism 3 is in the cooling operation state and closed when the switching mechanism 3 is in the heating operation state.

The bridge circuit 17 is provided between the heat source side heat exchanger 4 and the utilization side heat exchanger 6, and is connected to a receiver inlet pipe 18a connected to the inlet of the receiver 18, and the receiver 18. It is connected to the receiver outlet pipe 18b connected to the outlet of (). The bridge circuit 17 has four check valves 17a, 17b, 17c, and 17d in this modification. The inlet check valve 17a is a check valve that allows only the flow of the refrigerant from the heat source side heat exchanger 4 to the receiver inlet pipe 18a. The inlet check valve 17b is a check valve that allows only the flow of the refrigerant from the use-side heat exchanger 6 to the receiver inlet pipe 18a. That is, the inlet check valves 17a and 17b have a function of circulating the refrigerant from one of the heat source side heat exchanger 4 and the utilization side heat exchanger 6 to the receiver inlet pipe 18a. The outlet check valve 17c is a check valve that allows only the flow of the refrigerant from the receiver outlet pipe 18b to the use-side heat exchanger 6. The outlet check valve 17d is a check valve that allows only the flow of the refrigerant from the receiver outlet pipe 18b to the heat source side heat exchanger 4. That is, the outlet check valves 17c and 17d have a function of circulating the refrigerant from the receiver outlet pipe 18b to the other side of the heat source side heat exchanger 4 and the utilization side heat exchanger 6.

The receiver inlet expansion mechanism 5a is a mechanism for depressurizing the refrigerant provided in the receiver inlet pipe 18a. In this modification, an electric expansion valve is used. In the present modification, the receiver inlet expansion mechanism 5a depressurizes the high pressure refrigerant cooled in the heat source side heat exchanger 4 before sending it to the use side heat exchanger 6 during the cooling operation. In the heating operation, the high pressure refrigerant cooled in the use-side heat exchanger 6 is reduced in pressure before being sent to the heat source-side heat exchanger 4.

The receiver 18 is a container provided for temporarily collecting the refrigerant after being decompressed by the receiver inlet expansion mechanism 5a, the inlet of which is connected to the receiver inlet tube 18a, and the outlet thereof is the receiver outlet tube 18b. Is connected to. In addition, the receiver 18 extracts the refrigerant from the receiver 18 to the suction pipe 2a of the compression mechanism 2 (that is, the suction side of the compression element 2c on the front end side of the compression mechanism 2). The suction return pipe 18c which can be returned is connected. The suction return opening / closing valve 18d is provided in this suction return pipe 18c. The suction return opening / closing valve 18d is a solenoid valve in this modification.

The receiver outlet expansion mechanism 5b is a mechanism for depressurizing the refrigerant provided in the receiver outlet pipe 18b. In this modification, an electric expansion valve is used. In addition, in this modification, the receiver outlet expansion mechanism 5b is, at the time of cooling operation, until it becomes low pressure before sending the refrigerant | coolant reduced by the receiver inlet expansion mechanism 5a to the utilization side heat exchanger 6, Further, during the heating operation, the pressure reduced by the receiver inlet expansion mechanism 5a is further reduced until it reaches a low pressure before the refrigerant is sent to the heat source side heat exchanger 4.

Thus, when the switching mechanism 3 is in the cooling operation state by the bridge circuit 17, the receiver 18, the receiver inlet pipe 18a, and the receiver outlet pipe 18b, the heat source side heat exchanger 4 The high-pressure refrigerant cooled in the above) is transferred to the inlet check valve 17a of the bridge circuit 17, the receiver inlet expansion mechanism 5a of the receiver inlet pipe 18a, the receiver 18, and the receiver outlet pipe 18b. The receiver outlet expansion mechanism 5b and the outlet check valve 17c of the bridge circuit 17 can be sent to the use-side heat exchanger 6. When the switching mechanism 3 is in the heating operation state, the high pressure refrigerant cooled in the use-side heat exchanger 6 is used as the inlet check valve 17b and the receiver inlet pipe 18a of the bridge circuit 17. The heat source side heat exchanger (5) through the receiver inlet expansion mechanism 5a, the receiver 18, the receiver outlet expansion mechanism 5b of the receiver outlet pipe 18b, and the outlet check valve 17d of the bridge circuit 17 4) can be sent.

The rear end injection pipe 19 functions to branch off the refrigerant cooled in the heat source side heat exchanger 4 or the use side heat exchanger 6 and return it to the compression element 2d on the rear end side of the compression mechanism 2. Have In the present modification, the rear end injection pipe 19 is provided to branch the refrigerant flowing through the receiver inlet pipe 18a and return it to the suction side of the compression element 2d on the rear end side. More specifically, when the rear end injection pipe 19 is positioned upstream of the receiver inlet expansion mechanism 5a of the receiver inlet pipe 18a (that is, the switching mechanism 3 is in the cooling operation state), Between the heat source side heat exchanger 4 and the receiver inlet expansion mechanism 5a and when the switching mechanism 3 is in the heating operation state, the use side heat exchanger 6 and the receiver inlet expansion mechanism 5a And the refrigerant is branched off to return to the position on the downstream side of the intermediate cooler 7 of the intermediate refrigerant pipe 8. The rear end side injection pipe 19 is provided with a rear end side injection valve 19a capable of controlling the opening degree. The rear-end side injection valve 19a is a motor expansion valve in this modification.

The economizer heat exchanger 20 is a refrigerant that flows through the refrigerant cooled in the heat source side heat exchanger 4 or the use side heat exchanger 6 and the rear end injection tube 19 (more specifically, the rear end injection valve ( The heat exchanger which heat-exchanges refrigerant | coolant after pressure reduction to near intermediate pressure in 19a). In the present modification, when the economizer heat exchanger 20 is positioned at the upstream side of the receiver inlet expansion mechanism 5a of the receiver inlet pipe 18a (that is, the switching mechanism 3 is in the cooling operation state), Between the heat source side heat exchanger 4 and the receiver inlet expansion mechanism 5a and when the switching mechanism 3 is in the heating operation state, the use side heat exchanger 6 and the receiver inlet expansion mechanism 5a And a heat exchange between the refrigerant flowing between the refrigerant) and the refrigerant flowing through the rear-side injection pipe 19, and the refrigerant flows so that both refrigerants face each other. In addition, in this modification, the economizer heat exchanger 20 is provided in the upstream of the rear end injection pipe 19 of the receiver inlet pipe 18a. For this reason, the refrigerant cooled in the heat source side heat exchanger 4 or the use side heat exchanger 6 is injected into the rear end side injection tube before being heat exchanged in the economizer heat exchanger 20 in the receiver inlet tube 18a. Branched to 19), and in the economizer heat exchanger 20, heat exchange with the refrigerant flowing through the rear-side injection pipe 19 is performed.

Furthermore, various sensors are provided in the air conditioner 1 of this modification. Specifically, the intermediate refrigerant pipe 8 or the compression mechanism 2 is provided with an intermediate pressure sensor 54 for detecting the pressure of the refrigerant flowing through the intermediate refrigerant pipe 8. The economizer outlet temperature sensor which detects the temperature of the refrigerant | coolant in the outlet of the rear side injection pipe 19 side of the economizer heat exchanger 20 at the outlet of the injection pipe 19 side of the economizer heat exchanger 20 ( 55) is installed.

Next, operation | movement of the air conditioner 1 of this modification is demonstrated using FIGS. 14-18. Here, FIG. 15 is a pressure enthalpy diagram in which the refrigeration cycle in cooling operation in modified example 6 is shown, FIG. 16 is a temperature entropy diagram in which the refrigeration cycle in cooling operation in modified example 6 is shown, FIG. 17 is a pressure enthalpy diagram in which a refrigeration cycle in heating operation in modified example 6 is shown, and FIG. 18 is a temperature entropy diagram in which a refrigeration cycle in heating operation in modified example 6 is shown. In addition, operation control in the following cooling operation or heating operation is performed by the above-mentioned control part (not shown). In addition, in the following description, "high pressure" means the high pressure in a refrigerating cycle (that is, the pressure in the points D, D ', E, H of FIGS. 15, 16, and the points D, D of FIGS. 17, 18). ′, F, H in pressure, and “low pressure” means low pressure in the refrigerating cycle (that is, the pressure at points A, F, F ′ of FIGS. 15 and 16 and the pressures of FIGS. 17, 18). Means the pressure at points A, E, and E ', and the term "medium pressure" means the medium pressure in the refrigerating cycle (that is, at the points B1, C1, G, J, K of FIGS. 15 to 18). Pressure).

<Cooling operation>

At the time of cooling operation, the switching mechanism 3 is in the cooling operation state shown by the solid line of FIG. The opening degree of the receiver inlet expansion mechanism 5a and the receiver outlet expansion mechanism 5b are adjusted. And in order for the switching mechanism 3 to become a cooling operation state, the cooler opening-closing valve 12 opens and the intermediate | middle cooler bypass opening / closing valve 11 of the intermediate | middle cooler bypass pipe 9 is closed, The cooler 7 is in a state functioning as a cooler. Furthermore, the back stage injection valve 19a is also adjusted. More specifically, in this modification, the rear end injection valve 19a is opened so that the superheat degree of the refrigerant at the outlet of the rear end side injection pipe 19 side of the economizer heat exchanger 20 becomes the target value. The so-called superheat control, which is regulated, is to be made. In the present modification, the degree of superheat of the refrigerant at the outlet of the injection tube 19 side of the rear end side of the economizer heat exchanger 20 is converted to the saturation temperature by the intermediate pressure detected by the intermediate pressure sensor 54. This is obtained by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature detected by the economizer outlet temperature sensor 55. In addition, although not employ | adopted by this modification, a temperature sensor is provided in the inlet of the injection tube 19 side of the rear end side of the economizer heat exchanger 20, and the refrigerant temperature detected by this temperature sensor is used as the economizer outlet temperature sensor ( By subtracting from the refrigerant temperature detected by 55), the superheat degree of the refrigerant at the outlet of the injection tube 19 side of the rear end side of the economizer heat exchanger 20 may be obtained.

In the state of the refrigerant circuit 310, when the compression mechanism 2 is driven, low-pressure refrigerant (see point A in FIGS. 14 to 16) is sucked into the compression mechanism 2 from the suction pipe 2a, First, after compression to the intermediate pressure by the compression element 2c, it is discharged to the intermediate refrigerant pipe 8 (see point B1 in Figs. 14 to 16). The medium pressure refrigerant discharged from the compression element 2c on the front end side flows into the intermediate oil separator 16a constituting the intermediate oil separation mechanism 16, and the accompanying refrigeration oil separates as in the above-described embodiment. After that, it is sent to the intermediate cooler (7). In addition, the refrigeration oil separated from the medium pressure refrigerant in the intermediate oil separator (16a) flows into the intermediate oil return pipe (16b) constituting the intermediate oil separation mechanism (16) and enters the intermediate oil return pipe (16b). After the pressure reduction by the provided pressure reduction mechanism 16c is carried out, it returns to the compression mechanism 2 (here, the suction pipe 2a), and is suctioned by the compression mechanism 2 again. Next, the medium pressure refrigerant after the refrigerator oil is separated in the intermediate oil separation mechanism 16 is cooled by performing heat exchange with water or air as a cooling source in the intermediate cooler 7 (FIGS. 14 to 16). See point C1). The coolant cooled in the intermediate cooler 7 is further cooled by joining the coolant returned to the compression mechanism 2d on the rear end side from the rear end injection tube 19 (see point K in FIGS. 14 to 16). (See point G of FIGS. 14 to 16). Next, the medium pressure refrigerant joined with the refrigerant returning from the rear end injection pipe 19 is sucked into the compression element 2d connected to the rear end side of the compression element 2c and further compressed, thereby compressing the compression mechanism 2. ) Is discharged to the discharge tube 2b (see point D in FIGS. 14 to 16). Here, the high pressure refrigerant discharged from the compression mechanism 2 is subjected to a threshold pressure (that is, a threshold pressure Pcp at the critical point CP shown in FIG. 15) by a two-stage compression operation by the compression elements 2c and 2d. Compressed up to pressure. Then, the high pressure refrigerant discharged from the compression mechanism 2 is sent to the heat source side heat exchanger 4 functioning as a cooler of the refrigerant via the switching mechanism 3 to exchange heat with water or air as a cooling source. And cooling (see point E in Figs. 14 to 16). Then, the high-pressure refrigerant cooled in the heat source side heat exchanger 4 flows into the receiver inlet pipe 18a through the inlet check valve 17a of the bridge circuit 17, and part of the rear end injection pipe ( Branch to 19). And the refrigerant | coolant which flows through the rear side injection pipe 19 is sent to the economizer heat exchanger 20 after pressure_reduction | reduced_pressure | pressure_reduction | reduced to the vicinity of intermediate pressure in the rear injection valve 19a (refer to the point J of FIGS. 14-16). ). In addition, the refrigerant flowing through the receiver inlet pipe 18a after branching to the rear injection pipe 19 flows into the economizer heat exchanger 20, and heats with the refrigerant flowing through the rear injection pipe 19 to cool. (See point H in FIGS. 14-16). On the other hand, the refrigerant flowing through the rear-side injection pipe 19 is heated by performing heat exchange with the refrigerant flowing through the receiver inlet pipe 18a (see point K in FIGS. 14 to 16), and the intermediate cooler 7 as described above. In the cooled refrigerant. Then, the high-pressure refrigerant cooled in the economizer heat exchanger 20 is decompressed to near the saturation pressure by the receiver inlet expansion mechanism 5a and temporarily collected in the receiver 18 (point I in FIGS. 14 to 16). Reference). The refrigerant collected in the receiver 18 is sent to the receiver outlet pipe 18b, decompressed by the receiver outlet expansion mechanism 5b, and becomes a refrigerant having a low pressure gas-liquid abnormality, and the outlet check valve of the bridge circuit 17. Through 17c, it is sent to the use-side heat exchanger 6 which functions as a heater of the refrigerant (see point F in Figs. 14 to 16). The refrigerant in a low-pressure gas-liquid abnormal state sent to the use-side heat exchanger 6 is heated by heat exchange with water or air as a heating source, and evaporates (see point A in FIGS. 14 to 16). The low pressure refrigerant heated in the use-side heat exchanger 6 is again sucked into the compression mechanism 2 via the switching mechanism 3. In this manner, cooling operation is performed.

And in the structure of this modification, in the cooling operation which made the switching mechanism 3 into the cooling operation state similarly to the above-mentioned embodiment, since the intermediate | middle cooler 7 functions as a cooler, the intermediate | middle Compared with the case where the cooler 7 is not provided, the heat dissipation loss in the heat source side heat exchanger 4 can be reduced.

In addition, in the structure of this modification, the intermediate oil separation mechanism 16 is provided in the part between the compression element 2c of the front end side of the intermediate refrigerant pipe 8, and the inlet of the intermediate | middle cooler 7 similarly to the above-mentioned embodiment. ), It is possible to prevent oil depletion of the compression mechanism 2 due to the gathering of the refrigeration oil to the intermediate cooler 7, and also to reduce the heat transfer performance of the intermediate cooler 7 and increase in pressure loss. You can stop it. Furthermore, in the present modification, since the intermediate oil separation mechanism 16 is provided at a position on the upstream side of the connection between the intermediate refrigerant pipe 8 and the intermediate cooler bypass pipe 9, the intermediate cooler bypass pipe ( 9) The gathering of the refrigeration oil in the inside can also be prevented.

In addition, in the structure of this modification, the rear end side injection pipe 19 is provided, branching the refrigerant | coolant sent from the heat source side heat exchanger 4 to expansion mechanisms 5a, 5b, and returning it to the compression element 5d of the rear end side. In order to reduce the temperature, the temperature of the refrigerant sucked into the compression element 5d on the rear end side can be further lowered without radiating heat to the outside such as the intermediate cooler 7 (points C1 and G in FIG. 16). Reference). As a result, the temperature of the refrigerant discharged from the compression mechanism 2 is lowered (see points D and D 'in FIG. 16), and FIG. 16 is compared with the case where the rear end injection pipe 19 is not provided. By connecting points C1, D ', D, and G, the heat dissipation loss corresponding to the area enclosed can be made smaller, so that the driving efficiency can be further improved.

Moreover, in the structure of this modification, the economizer heat exchanger 20 which heat-exchanges the refrigerant | coolant sent from the heat source side heat exchanger 4 to the expansion mechanisms 5a, 5b, and the refrigerant | coolant which flows through the rear side injection pipe 19 is further provided. Since it is provided, the refrigerant | coolant sent to the expansion mechanism 5a, 5b from the heat-source side heat exchanger 4 can be cooled by the refrigerant | coolant which flows through the downstream injection pipe 19 (point E of FIG. 15, FIG. 16). , See point H), when the rear-side injection pipe 19 and the economizer heat exchanger 20 are not provided (in this case, in FIG. 15 and FIG. 16, point A → point B1 → point C1 → point D ′). The cooling capacity per unit flow rate of the refrigerant in the use-side heat exchanger 6 can be made higher than that of the refrigeration cycle in the order of point E to point F '.

<Heating driving>

At the time of heating operation, the switching mechanism 3 is in the heating operation state shown by the broken line of FIG. The opening degree of the receiver inlet expansion mechanism 5a and the receiver outlet expansion mechanism 5b are adjusted. And in order for the switching mechanism 3 to become a heating operation state, the cooler opening-closing valve 12 is closed and the intermediate | middle cooler bypass opening / closing valve 11 of the intermediate | middle cooler bypass pipe 9 opens, The cooler 7 does not function as a cooler. Moreover, the opening degree is also adjusted also by the superheat | overheat degree control similar to the case of cooling operation also in the rear injection valve 19a.

In the state of the refrigerant circuit 310, when the compression mechanism 2 is driven, the low pressure refrigerant (see point A in FIGS. 14, 17, and 18) is transferred from the suction pipe 2a to the compression mechanism 2. It is sucked in and is first compressed to an intermediate pressure by the compression element 2c and then discharged to the intermediate refrigerant pipe 8 (see point B1 in Figs. 14, 17 and 18). The medium pressure refrigerant discharged from the compression element 2c on the front end side flows into the intermediate oil separator 16a constituting the intermediate oil separation mechanism 16, and the accompanying refrigeration oil separates as in the above-described embodiment. After that, it is sent to the intermediate cooler (7). In addition, the refrigeration oil separated from the medium pressure refrigerant in the intermediate oil separator (16a) flows into the intermediate oil return pipe (16b) constituting the intermediate oil separation mechanism (16) and enters the intermediate oil return pipe (16b). After the pressure reduction by the provided pressure reduction mechanism 16c is carried out, it returns to the compression mechanism 2 (here, the suction pipe 2a), and is suctioned by the compression mechanism 2 again. Next, the intermediate pressure refrigerant after the refrigeration oil is separated in the intermediate oil separation mechanism 16 does not pass through the intermediate cooler 7 (i.e., without being cooled) unlike in the cooling operation. Refrigerant (FIG. 14, 17) which passes through the bypass pipe 9 (refer to the point C1 of FIG. 14, FIG. 17, FIG. 18) and is returned to the compression mechanism 2d of the rear end side from the rear side injection tube 19. FIG. And cooling by joining (see point K in FIG. 18) (see point G in FIGS. 14, 17 and 18). Next, the medium pressure refrigerant joined with the refrigerant returning from the rear end side injection pipe 19 is sucked into the compression element 2d connected to the rear end side of the compression element 2c, and further compressed, and the compression mechanism 2 Is discharged to the discharge tube 2b (see point D in Figs. 14, 17 and 18). Here, the high-pressure refrigerant discharged from the compression mechanism 2 is applied to the critical pressure (that is, the critical point CP shown in FIG. 17) by the two-stage compression operation by the compression elements 2c and 2d as in the cooling operation. It is compressed to the pressure exceeding the critical pressure Pcp). Then, the high pressure refrigerant discharged from the compression mechanism 2 is sent to the use side heat exchanger 6 which functions as a cooler of the refrigerant via the switching mechanism 3 to exchange heat with water or air as a cooling source. And cooling (see point F in Figs. 14, 17 and 18). Then, the high-pressure refrigerant cooled in the use-side heat exchanger 6 flows into the receiver inlet pipe 18a via the inlet check valve 17b of the bridge circuit 17, and part of the rear end injection pipe ( Branch to 19). And the refrigerant | coolant which flows through the rear side injection pipe 19 is sent to the economizer heat exchanger 20 after depressurizing to the vicinity of intermediate pressure in the rear injection valve 19a (FIG. 14, FIG. 17, FIG. 18). See point J). In addition, the refrigerant flowing through the receiver inlet pipe 18a after branching to the rear injection pipe 19 flows into the economizer heat exchanger 20, and heats with the refrigerant flowing through the rear injection pipe 19 to cool. (See point H in FIGS. 14, 17, 18). On the other hand, the refrigerant flowing through the rear-side injection tube 19 is heated by performing heat exchange with the refrigerant flowing through the receiver inlet tube 18a (see point K in Figs. 14, 17, and 18), and the front side as described above. Of the medium pressure refrigerant discharged from the compression element 2c. And the high pressure refrigerant | coolant cooled in the economizer heat exchanger 20 is pressure-reduced to near saturation pressure by the receiver inlet expansion mechanism 5a, and it collects temporarily in the receiver 18 (FIG. 14, FIG. 17, FIG. 18). See point I). The refrigerant collected in the receiver 18 is sent to the receiver outlet pipe 18b, decompressed by the receiver outlet expansion mechanism 5b, and becomes a refrigerant having a low pressure gas-liquid abnormality, and the outlet check valve of the bridge circuit 17. Through 17d, it is sent to the heat source side heat exchanger 4 which functions as a heater of a refrigerant (refer to the point E of FIG. 14, FIG. 17, FIG. 18). Then, the low pressure gas-liquid abnormality refrigerant sent to the heat source side heat exchanger 4 is heated by evaporating heat with water or air as a heating source and evaporated (see point A in Figs. 14, 17 and 18). . The low pressure refrigerant heated in the heat source side heat exchanger 4 is again sucked into the compression mechanism 2 via the switching mechanism 3. In this way, heating operation is performed.

And in the structure of this modification, in the heating operation which made the switching mechanism 3 into the heating operation state, the cooler opening / closing valve 12 is closed and the intermediate | middle cooler bypass opening / closing of the intermediate | middle cooler bypass pipe 9 is carried out. Since the intermediate cooler 7 does not function as a cooler by opening the valve 11, the intermediate cooler 7 is used as a cooler in the same manner as in the case where only the intermediate cooler 7 is installed or the above-described cooling operation. As compared with the case of functioning, the fall of the temperature of the refrigerant | coolant discharged from the compression mechanism 2 is suppressed (refer FIG. 18, point D and D '). For this reason, this air conditioner 1 suppresses heat radiation to the outside compared with the case where only the intermediate | middle cooler 7 is installed or when the intermediate | middle cooler 7 functions as a cooler similarly to the cooling operation mentioned above, It is possible to suppress the decrease in the temperature of the coolant supplied to the use-side heat exchanger 6 which functions as the cooler of the coolant, to suppress the decrease in the heating capacity and to prevent the decrease in the operating efficiency.

Moreover, in the structure of this modification, the intermediate oil separation mechanism (a part) between the compression element 2c of the front end side of the intermediate refrigerant pipe 8, and the inlet of the intermediate | middle cooler 7 is carried out similarly to the cooling operation mentioned above. 16), it is possible to prevent oil depletion of the compression mechanism 2 due to the gathering of the refrigeration oil to the intermediate cooler 7, and also to reduce the heat transfer performance of the intermediate cooler 7 and increase the pressure loss. Can be prevented.

In addition, in the structure of this modification, the rear side injection pipe 19 is provided, branching off the refrigerant | coolant sent from the utilization side heat exchanger 6 to the expansion mechanisms 5a, 5b, and returning it to the compression element 5d of the rear side. Since the temperature of the refrigerant discharged from the compression mechanism 2 is lowered (see points D and D 'of FIG. 18), the unit flow rate of the refrigerant in the use-side heat exchanger 6 is thereby reduced. The sugar heating capacity becomes small (see points D, D ', and F in Fig. 17), but the flow rate of the refrigerant discharged from the compression element 2d on the rear end side increases, so that the heat exchanger 6 in the use side The heating capacity of is ensured, and operation efficiency can be improved.

Moreover, in the structure of this modification, the economizer heat exchanger 20 which heat-exchanges the refrigerant | coolant sent from the utilization side heat exchanger 6 to the expansion mechanisms 5a, 5b, and the refrigerant | coolant which flows through the back side injection pipe 19 is further provided. Since it is provided, the refrigerant flowing through the rear-side injection pipe 19 can be heated by the refrigerant sent from the use-side heat exchanger 6 to the expansion mechanisms 5a and 5b (Fig. 17 and Fig. 18, point J). , See point K), when the rear injection pipe 19 and the economizer heat exchanger 20 are not provided (in this case, in FIG. 17 and FIG. 18, point A to point B1 to point C1 to point D '). As compared with the point F → point E ', the refrigeration cycle is performed), the flow rate of the refrigerant discharged from the compression element 2d on the rear end side can be increased.

In addition, as an advantage common to the cooling operation and the heating operation, in the configuration of the present modification, as the economizer heat exchanger 20, the heat source side heat exchanger 4 or the use side heat exchanger 6 to the expansion mechanisms 5a and 5b. The heat source side heat exchanger 4 or the use side heat exchanger in the economizer heat exchanger 20 is employed because a heat exchanger having a flow path is provided so that the refrigerant to be sent and the refrigerant flowing through the rear-side injection pipe 19 face each other. The temperature difference between the refrigerant sent from 6) to the expansion mechanisms 5a and 5b and the refrigerant flowing through the rear-side injection pipe 19 can be reduced, and high heat exchange efficiency can be obtained. In addition, in the structure of this modification, the heat source side heat exchanger before the refrigerant | coolant sent from the heat source side heat exchanger 4 or the utilization side heat exchanger 6 to the expansion mechanisms 5a, 5b is heat-exchanged in the economizer heat exchanger 20. Moreover, as shown in FIG. Since the rear end side injection pipe 19 is provided so as to branch off the refrigerant sent from the gas 4 or the use side heat exchanger 6 to the expansion mechanisms 5a and 5b, the rear end side of the economizer heat exchanger 20 is provided. The flow rate of the refrigerant sent from the heat source side heat exchanger 4 or the use side heat exchanger 6 which performs heat exchange with the refrigerant flowing through the injection pipe 19 to the expansion mechanisms 5a and 5b can be reduced, and the economizer heat exchanger ( The amount of heat exchanged in 20) can be made small, and the size of the economizer heat exchanger 20 can be made small.

In addition, although detailed description is abbreviate | omitted here, instead of the two-stage compression type compression mechanism 2, two-stage compression, such as a three-stage compression type (for example, the compression mechanism 102 in the modification 3), etc. Compression having a two-stage compression mechanism (203, 204) in the fourth modified example may be employed in place of the two-stage compression mechanism (2) instead of the two-stage compression mechanism. As a refrigerant circuit 410 employing the mechanism 202 (see FIG. 19), a parallel multistage compression type compression mechanism in which multiple compression systems are connected in parallel may be employed. In this case, The effect similar to a modification can be acquired. Moreover, in the air conditioner 1 of this modification, the receiver inlet expansion mechanism 5a, the receiver outlet expansion mechanism 5b, the receiver 18, the rear side injection pipe 19, or the economizer heat exchanger 20 Although the bridge circuit 17 is employ | adopted from the viewpoint of making constant the flow direction of the refrigerant | coolant with respect to a cooling operation and a heating operation, for example, only one of the rear stages at the time of a cooling operation or a heating operation is adopted. Receiver inlet expansion mechanism 5a, receiver outlet expansion mechanism 5b, receiver 18, rear side injection tube 19, or the like, using side injection tube 19 or economizer heat exchanger 20, or the like. If it is not necessary to make the flow direction of the coolant to the economizer heat exchanger 20 constant regardless of the cooling operation and the heating operation, the bridge circuit 17 may be omitted.

(9) Modification 7

Although the refrigerant | coolant circuit 310 (refer FIG. 14) and refrigerant | coolant circuit 410 (refer FIG. 19) in the above-mentioned modified example 6 has the structure which the one use side heat exchanger 6 was connected, it is a some using side. In addition to connecting the heat exchanger 6, the use-side heat exchanger 6 may be configured to be individually started / stopped.

For example, as shown in FIG. 20, in the refrigerant circuit 310 (refer to FIG. 15) of the modified example 7 in which the two-stage compression type compression mechanism 2 was employ | adopted, the two utilization side heat exchangers 6 were carried out. Is connected to each other, the use side expansion mechanism 5c is provided corresponding to the bridge circuit 17 side end of each use side heat exchanger 6, and the receiver outlet expansion mechanism provided in the receiver outlet pipe 18b ( 5b) is deleted, and further, instead of the outlet check valve 17d of the bridge circuit 17, the refrigerant circuit 510 provided with the bridge outlet expansion mechanism 5d is provided, or as shown in FIG. In the refrigerant circuit 410 (see Fig. 19) of the modification 6 in which the compression mechanism 202 of the parallel two-stage compression type is adopted, two use-side heat exchangers 6 are connected and each use-side heat exchanger The utilization side expansion mechanism 5c is provided corresponding to the bridge circuit 17 side end of (6), and the receiver outlet pipe 18b is provided. The receiver outlet expansion mechanism 5b that has been installed is deleted, and further, the refrigerant outlet circuit 510 provided with the bridge outlet expansion mechanism 5d may be replaced with the outlet check valve 17d of the bridge circuit 17. Do.

And in the structure of this modification, the bridge exit expansion mechanism 5d will be in a fully closed state at the time of cooling operation, and the utilization side expansion instead of the receiver outlet expansion mechanism 5b in the modification 7 is carried out. The mechanism 5c further depressurizes the refrigerant depressurized by the receiver inlet expansion mechanism 5a until it reaches a low pressure before sending it to the use-side heat exchanger 6. Although different from the operation, the operation is basically the same as that of the operation during the cooling operation (Figs. 14 to 16 and related description) in the modification 6. In the heating operation, in order to control the flow rate of the refrigerant flowing through each use side heat exchanger 6, the opening degree of the use side expansion mechanism 5c is adjusted, and the receiver outlet expansion mechanism in the modification 6 is used. Instead of (5b), before the bridge outlet expansion mechanism 5d sends the refrigerant decompressed by the receiver inlet expansion mechanism 5a to the heat source side heat exchanger 4, it further depressurizes the operation until the pressure is low. Although it differs from the operation | movement at the time of the heating operation in the modification 6, about another operation | movement is basically the same as the operation | movement at the time of the heating operation in the modification 6 (FIG. 14, FIG. 17, FIG. 18 and its related description). .

And also in the structure of this modification, the effect similar to the above-mentioned modification 6 can be obtained.

In addition, although detailed description is abbreviate | omitted here, the three-stage compression type (for example, the compression mechanism 102 in modified example 3) etc. instead of the two-stage compression type | mold compression mechanisms 2, 203, and 204 are mentioned. A multistage compression mechanism may be employed rather than the same two-stage compression type.

(10) another embodiment

As mentioned above, although the Example of this invention and its modification were demonstrated based on drawing, the specific structure is not limited to these Example and its modification, It can change in the range which does not deviate from the summary of invention.

For example, in the above-described embodiments and modifications thereof, the use-side heat exchanger is used while using water or brine as a heating source or a cooling source that performs heat exchange with a refrigerant flowing through the use-side heat exchanger 6. The present invention may be applied to a so-called chiller-type air conditioner provided with heat exchanged water or brine in the machine 6 and a secondary heat exchanger for exchanging indoor air.

Moreover, even if it is the refrigeration apparatus of another type of the chiller type air conditioner mentioned above, this invention is applicable as long as it performs a multistage compression type refrigeration cycle using the refrigerant | coolant which operates in a supercritical area as a refrigerant | coolant.

In addition, the refrigerant operating in the supercritical region is not limited to carbon dioxide, and ethylene, ethane, nitrogen oxide, or the like may be used.

According to the present invention, it is possible to prevent oil depletion of the compression mechanism in a refrigerating device that performs a multistage compression type refrigeration cycle using a refrigerant operating in a supercritical region.

1: air conditioner (refrigeration unit)
2, 102, 202: compression mechanism
4: heat source side heat exchanger
5: expansion mechanism
6: use side heat exchanger
7: medium cooler
8: intermediate refrigerant pipe
16: intermediate oil separation mechanism
16a: middle oil separator
16b: middle oil return tube
16d: header

Claims (4)

It is a refrigeration unit using a refrigerant operating in a supercritical zone,
A compression mechanism (2, 102, 202) having a plurality of compression elements, and configured to sequentially compress refrigerant discharged from the compression element on the front side of the plurality of compression elements into the compression element on the rear end side; ,
A heat source side heat exchanger (4),
Expansion mechanisms 5, 5a, 5b, 5c, and 5d for depressurizing the refrigerant;
The use-side heat exchanger (6),
Refrigerant which is installed in the intermediate refrigerant pipe 8 for sucking the refrigerant discharged from the compression element on the front end side into the compression element on the rear end side, and is discharged from the compression element on the front side and sucked into the compression element on the rear end side. An intermediate cooler 7 functioning as a cooler of
The refrigeration oil is provided at a portion between the compression element on the front end side of the intermediate refrigerant pipe and the inlet of the intermediate cooler, and separates the refrigerant oil accompanying the refrigerant discharged from the compression element on the front end side from the refrigerant to form the compression mechanism. Slewing Intermediate Oil Separation Mechanism (16)
Refrigeration apparatus (1) having a. The method of claim 1,
The intermediate oil separation mechanism 16 is an intermediate oil separator 16a for separating refrigerant oil accompanying the refrigerant discharged from the compression element on the front end side from the refrigerant, and connected to the intermediate oil separator and separated from the refrigerant. Refrigeration apparatus 1, having an intermediate oil return tube 16b for returning the refrigeration oil to compression mechanisms 2, 102, 202. The method of claim 1,
The intermediate oil separation mechanism 16 is an intermediate oil for connecting the header 16d provided at the inlet of the intermediate cooler 7, the lower end of the header, and the compression mechanisms 2, 102 and 202. Refrigerating apparatus 1 which has return tube 16b. 4. The method according to any one of claims 1 to 3,
Refrigeration apparatus (1), wherein the refrigerant operating in the supercritical zone is carbon dioxide.

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