Refrigeration cycle device

Abstract

A refrigeration cycle device (100) comprises a main circuit (MC) and an injection circuit (IC). The main circuit (MC) includes a compressor (1), a condenser (2) for condensing, an expansion valve (3), and an evaporator (4). The injection circuit (IC) includes an injection expansion valve (10) for reducing the pressure of a refrigerant flowing out from the main circuit (MC), and is connected to the main circuit (MC) and to an intermediate pressure side or a suction side of the compressor (1). The refrigerating machine oil is an immiscible oil. In the flow of the refrigerant, the injection circuit (IC) has a branching portion (I1) that branches from the main circuit (MC) and a merging portion (I2) that merges with the main circuit (MC). The height position of the branching portion (I1) is higher than the height position of the merging portion (I2).

Description

Refrigeration cycle equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] The refrigeration cycle device may be provided with an injection circuit to cool the compressor by injecting a portion of the liquid refrigerant condensed in the condenser into the compressor to suppress the compressor discharge temperature. In the refrigeration cycle device provided with the injection circuit, an incompatible oil that is immiscible with the refrigerant may be used as the refrigerating machine oil.

[0003] For example, Japanese Patent Application Laid-Open No. 2009-228972 (Patent Document 1) describes the use of incompatible refrigerating machine oils in a refrigeration device equipped with an injection pipe.

[0004] JP 2009-228972 A

[0005] As described in the above publication, when an incompatible oil that is incompatible with the refrigerant is used as the refrigeration oil in a refrigeration cycle device equipped with an injection circuit, the refrigeration oil may accumulate in the injection circuit, causing the refrigeration oil to run out in the compressor, which reduces the lubrication of the compressor and reduces the reliability of the refrigeration cycle device.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a refrigeration cycle device that can improve the reliability of the refrigeration cycle device by suppressing the accumulation of incompatible oil, which is refrigerant oil, in the injection circuit.

[0007] The refrigeration cycle device of the present disclosure includes a main circuit and an injection circuit. The main circuit includes a compressor that compresses a refrigerant and discharges refrigerant oil together with the refrigerant, a condenser that condenses the refrigerant discharged from the compressor, an expansion valve that depressurizes the refrigerant flowing out from the condenser, and an evaporator that evaporates the refrigerant flowing out from the expansion valve. The injection circuit includes an injection expansion valve that depressurizes the refrigerant flowing out from the main circuit and is connected to the main circuit and the intermediate pressure side or suction side of the compressor. The refrigerant oil is an incompatible oil. The injection circuit includes a branch portion that branches off from the main circuit and a junction portion that merges into the main circuit in the refrigerant flow. The branch portion is located at a higher height than the junction portion.

[0008] According to the refrigeration cycle device of the present disclosure, the reliability of the refrigeration cycle device can be improved by suppressing the accumulation of incompatible oil, which is refrigerating machine oil, in the injection circuit.

[0009] Fig. 1 is a refrigerant circuit diagram of a refrigeration cycle device according to an embodiment; Fig. 2 is a refrigerant circuit diagram of a modified example 1 of a refrigeration cycle device according to an embodiment; Fig. 3 is a refrigerant circuit diagram of a modified example 2 of a refrigeration cycle device according to an embodiment; Fig. 4 is a refrigerant circuit diagram of a modified example 3 of a refrigeration cycle device according to an embodiment; Fig. 5 is a schematic perspective cross-sectional view of an upward part of a branch part of an injection circuit in a modified example 4 of a refrigeration cycle device according to an embodiment.

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference numerals, and overlapping descriptions will not be repeated.

[0011] A configuration of a refrigeration cycle apparatus 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100 according to the embodiment. The refrigeration cycle apparatus 100 according to the embodiment is, for example, a refrigerator.

[0012] 1, the refrigeration cycle apparatus 100 according to the embodiment includes a main circuit MC and an injection circuit IC. The refrigeration cycle apparatus 100 according to the embodiment also includes a control device 20.

[0013] The refrigerant circulating in the refrigeration cycle device 100 is, for example, carbon dioxide (CO ２ ) etc.

[0014] The refrigerating machine oil is an incompatible oil, such as ether oil or polyalkylene glycol (PAG) oil.

[0015] The main circuit MC has a compressor 1, a condenser 2, an expansion valve 3, and an evaporator 4. The main circuit MC is configured by connecting the compressor 1, the condenser 2, the expansion valve 3, and the evaporator 4 with piping. The main circuit MC is configured so that the refrigerant flows through the compressor 1, the condenser 2, the expansion valve 3, and the evaporator 4 in this order.

[0016] The compressor 1 is configured to compress a refrigerant and discharge refrigeration oil together with the refrigerant. The compressor 1 is configured to compress and discharge the refrigerant that it has drawn in. The compressor 1 has a suction port P1 provided on the suction side, a discharge port P2 provided on the discharge side, and an intermediate-pressure port P3 provided on the intermediate-pressure side.

[0017] The compressor 1 may be configured to have a variable capacity. The compressor 1 may be configured such that the capacity is changed by adjusting the rotation speed through changing the frequency based on an instruction from the control device 20.

[0018] The condenser 2 is configured to condense the refrigerant discharged from the compressor 1. The condenser 2 is configured to cool and condense the refrigerant discharged from the compressor 1. The condenser 2 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube passing through the plurality of fins.

[0019] The expansion valve 3 is configured to reduce the pressure of the refrigerant flowing out from the condenser 2. The expansion valve 3 is, for example, a solenoid valve. The expansion valve 3 is configured to be able to adjust the flow rate of the refrigerant based on an instruction from the control device 20.

[0020] The evaporator 4 is configured to evaporate the refrigerant that flows out from the expansion valve 3. The evaporator 4 is configured to heat and evaporate the refrigerant that flows out from the expansion valve 3. The evaporator 4 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube that passes through the plurality of fins.

[0021] The injection circuit IC is connected to the main circuit MC and the intermediate pressure side or suction side of the compressor 1. In this embodiment, the injection circuit IC is connected to the main circuit MC and the intermediate pressure side of the compressor 1. In this embodiment, the injection circuit IC is connected to the main circuit MC between the condenser 2 and the expansion valve 3 and to the intermediate pressure port P3 of the compressor 1.

[0022] The injection circuit IC has an injection expansion valve IE that reduces the pressure of the refrigerant flowing out from the main circuit MC. The injection expansion valve IE is configured to control the discharge temperature of the compressor 1. The injection expansion valve IE is configured to reduce the pressure of the refrigerant to an intermediate pressure.

[0023] The injection circuit IC has a branch portion I1 that branches off from the main circuit MC and a junction portion I2 that joins the main circuit MC in the refrigerant flow. The branch portion I1 is located higher in height than the junction portion I2. The branch portion I1 is located higher in height than the junction portion I2.

[0024] The control device 20 is configured to control the entire refrigeration cycle apparatus 100. The control device 20 is configured to control the compressor 1 and the expansion valve 3 in the main circuit MC. The control device 20 is configured to control the injection expansion valve IE in the injection circuit IC. The control device 20 is configured, for example, by a microcomputer. The control device 20 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. A control program is stored in the ROM.

[0025] The refrigeration cycle device 100 is configured to be able to select between normal operation and oil recovery operation. In normal operation, refrigerant and refrigerating machine oil flow through the main circuit MC and the injection circuit IC. In oil recovery operation, refrigerant and refrigerating machine oil flow through the main circuit MC and the injection circuit IC, and the refrigerating machine oil is recovered into the compressor 1. The opening degree of the injection expansion valve IE in the oil recovery operation is larger than the opening degree of the injection expansion valve IE in the normal operation.

[0026] When the injection circuit IC is connected to the intermediate pressure side of the compressor 1, the pressure at the branch point I1 is Pin, the pressure at the junction point I2 is Pout, the discharge pressure of the compressor 1 is Pd, and the suction pressure of the compressor 1 is Ps. The relationships of Pin, Pout, Pd, and Ps are Pin / Pout>Pd / (Pd×Ps). １／２ This becomes:

[0027] Next, the operation of the refrigeration cycle apparatus 100 according to the embodiment will be described. The operation of the refrigeration cycle apparatus 100 during normal operation will be described.

[0028] The refrigerant that flows into the compressor 1 from the suction port P1 and the intermediate pressure port P3 is compressed by the compressor 1 to become high-temperature, high-pressure gas refrigerant and is discharged from the discharge port P2 of the compressor 1. This high-temperature, high-pressure gas refrigerant flows into the condenser 2, where it is condensed to become liquid refrigerant, and then flows out of the condenser 2.

[0029] The liquid refrigerant flowing out of the condenser 2 branches off into the main circuit MC and the injection circuit IC. The liquid refrigerant flowing into the injection circuit IC is decompressed to an intermediate pressure by the injection expansion valve IE and flows into the intermediate pressure port P3 of the compressor 1.

[0030] The liquid refrigerant flowing through the main circuit MC is decompressed by the expansion valve 3 to become a low-pressure gas-liquid two-phase refrigerant, and flows out of the expansion valve 3. This gas-liquid two-phase refrigerant flows into the evaporator 4, where it is evaporated to become gas refrigerant. This gas refrigerant flows into the suction port P1 of the compressor 1. In this way, the refrigerant circulates through the refrigeration cycle apparatus 100 refrigeration circuit.

[0031] The oil recovery operation of the refrigeration cycle apparatus 100 will be described. In the oil recovery operation of the refrigeration cycle apparatus 100, the opening degree of the injection expansion valve IE is different from that in the normal operation of the refrigeration cycle apparatus 100. The opening degree of the injection expansion valve IE in the oil recovery operation of the refrigeration cycle apparatus 100 is larger than the opening degree of the injection expansion valve IE in the normal operation. In the oil recovery operation of the refrigeration cycle apparatus 100, the amounts of refrigerant and refrigeration oil flowing through the injection circuit IC are greater than in the normal operation of the refrigeration cycle apparatus 100. As a result, in the oil recovery operation of the refrigeration cycle apparatus 100, refrigeration oil is recovered into the compressor 1.

[0032] Next, the effects of the refrigeration cycle apparatus 100 according to the embodiment will be described. In the refrigeration cycle apparatus 100 according to the embodiment, the height position of the branch section I1 is higher than the height position of the junction section I2. Therefore, the immiscible oil, which is refrigerating machine oil, flows from the branch section I1 to the junction section I2 due to gravity, which makes it possible to prevent the immiscible oil, which is refrigerating machine oil, from accumulating in the injection circuit IC. This makes it possible to prevent the immiscible oil, which is refrigerating machine oil, from running out in the compressor 1. This increases the lubricity of the compressor 1, thereby improving the reliability of the refrigeration cycle apparatus 100.

[0033] The refrigeration cycle apparatus 100 according to the embodiment includes an injection circuit IC. Therefore, by causing a portion of the liquid refrigerant condensed in the condenser 2 to flow into the compressor 1, the compressor 1 can be cooled and the discharge temperature of the compressor 1 can be suppressed.

[0034] Furthermore, since the injection circuit IC cools the compressor 1 with liquid refrigerant to suppress the discharge temperature of the compressor 1, it is necessary to ensure the flow rate of the refrigerant flowing through the injection circuit IC. If the refrigerant flow velocity in the injection circuit IC is increased to suppress refrigeration oil accumulation in the injection circuit IC, the following problem occurs. If the piping diameter of the injection circuit IC is reduced to increase the refrigerant flow velocity in the injection circuit IC, it becomes difficult to ensure the flow rate of the refrigerant flowing through the injection circuit IC. In the refrigeration cycle apparatus 100 according to the embodiment, the piping diameter of the injection circuit IC is not reduced, so the flow rate of the refrigerant flowing through the injection circuit IC can be ensured.

[0035] Furthermore, if an excess amount of refrigerant is supplied to the injection circuit IC, the amount of work done by the compressor 1 to compress the refrigerant increases, thereby reducing the energy-saving performance of the refrigeration cycle apparatus 100. In the refrigeration cycle apparatus 100 according to the embodiment, an excess amount of refrigerant is not supplied to the injection circuit IC, thereby improving the energy-saving performance of the refrigeration cycle apparatus 100.

[0036] In the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the intermediate pressure side of the compressor 1. Therefore, by causing the refrigerant to flow from the injection circuit IC into the intermediate pressure side of the compressor 1, it is possible to eliminate the power required by the compressor 1 to compress the refrigerant from low pressure to intermediate pressure. This improves the energy saving performance of the refrigeration cycle apparatus 100.

[0037] In the refrigeration cycle apparatus 100 according to the embodiment, the opening degree of the injection expansion valve IE during the oil recovery operation is larger than the opening degree of the injection expansion valve IE during the normal operation. Therefore, the amount of refrigerant and refrigerating machine oil flowing through the injection circuit IC can be increased compared to the normal operation during the oil recovery operation. Therefore, during the oil recovery operation, refrigerating machine oil can be recovered from the injection circuit IC to the compressor 1.

[0038] In the refrigeration cycle apparatus 100 according to the embodiment, when the injection circuit IC is connected to the intermediate pressure side of the compressor 1, the pressure at the branching section I1 is Pin, the pressure at the confluence section I2 is Pout, the discharge pressure of the compressor 1 is Pd, and the suction pressure of the compressor 1 is Ps. Then, Pin, Pout, Pd, and Ps satisfy the following relationship: Pin / Pout>Pd / (Pd×Ps). １／２ Therefore, by increasing the pressure ratio between the pressure Pin at the branch point I1 and the pressure Pout at the junction point I2, the flow rate of refrigerating machine oil flowing through the injection circuit IC can be increased.

[0039] Next, a description will be given of a modified example of the refrigeration cycle apparatus 100 according to the embodiment. The modified example of the refrigeration cycle apparatus 100 according to the embodiment has the same configuration and operation as the refrigeration cycle apparatus 100 according to the embodiment unless otherwise specified.

[0040] A first modified example of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a refrigerant circuit diagram of the first modified example of the refrigeration cycle apparatus 100 according to the embodiment. In the first modified example of the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the suction side of the compressor 1. In this embodiment, the injection circuit IC is connected to the main circuit MC between the condenser 2 and the expansion valve 3 and the main circuit MC between the compressor 1 and the evaporator 4.

[0041] Next, the operation of the first modification of the refrigeration cycle apparatus 100 according to the embodiment will be described.

[0042] The refrigerant that flows into the compressor 1 from the suction port P1 is compressed by the compressor 1 to become high-temperature, high-pressure gas refrigerant, and is discharged from the discharge port P2 of the compressor 1. This high-temperature, high-pressure gas refrigerant flows into the condenser 2, where it is condensed to become liquid refrigerant, and then flows out of the condenser 2.

[0043] The liquid refrigerant flowing out of the condenser 2 branches off into the main circuit MC and the injection circuit IC. The liquid refrigerant flowing into the injection circuit IC is decompressed to a low pressure by the injection expansion valve IE and flows into the suction port P1 of the compressor 1 from a junction I2 connected to the main circuit MC between the compressor 1 and the evaporator 4.

[0044] The liquid refrigerant flowing through the main circuit MC is decompressed by the expansion valve 3 to become a low-pressure gas-liquid two-phase refrigerant, and flows out of the expansion valve 3. This gas-liquid two-phase refrigerant flows into the evaporator 4, where it is evaporated to become gas refrigerant. This gas refrigerant flows into the suction port P1 of the compressor 1. In this way, the refrigerant circulates through the refrigeration cycle apparatus 100 refrigeration circuit.

[0045] Next, an explanation will be given of the function exchange of the first modified example of the refrigeration cycle apparatus 100 according to the embodiment.

[0046] In the first modification of the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the suction side of the compressor 1. Therefore, when the pressure on the intermediate pressure side of the compressor 1 is higher than the pressure of the refrigerant flowing out from the injection expansion valve IE, the refrigerant can be made to flow into the compressor 1 by flowing from the injection circuit IC into the suction side of the compressor 1.

[0047] A second modification of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a refrigerant circuit diagram of the second modification of the refrigeration cycle apparatus 100 according to the embodiment. The second modification of the refrigeration cycle apparatus 100 according to the embodiment differs from the refrigeration cycle apparatus 100 according to the embodiment in that it includes an internal heat exchanger 10.

[0048] The second modification of the refrigeration cycle apparatus 100 according to the embodiment further includes an internal heat exchanger 10. The injection expansion valve IE is disposed upstream of the internal heat exchanger 10 in the refrigerant flow direction in the injection circuit IC.

[0049] The internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing between the condenser 2 and the expansion valve 3 in the main circuit MC and the refrigerant flowing through the injection circuit IC. The internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing out of the condenser 2 and the refrigerant flowing out of the injection expansion valve IE in the injection circuit IC. The internal heat exchanger 10 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the injection circuit IC are counter-flowing. In other words, the internal heat exchanger 10 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the injection circuit IC are counter-flowing.

[0050] Next, the operation of the second modification of the refrigeration cycle apparatus 100 according to the embodiment will be described.

[0051] The refrigerant that flows into the compressor 1 from the suction port P1 and the intermediate pressure port P3 is compressed by the compressor 1 to become high-temperature, high-pressure gas refrigerant and is discharged from the discharge port P2 of the compressor 1. This high-temperature, high-pressure gas refrigerant flows into the condenser 2, where it is condensed to become liquid refrigerant, and then flows out of the condenser 2.

[0052] This liquid refrigerant flows into the internal heat exchanger 10. The liquid refrigerant flowing out of the internal heat exchanger 10 branches off and flows into the main circuit MC and the injection circuit IC. The liquid refrigerant that flows into the injection circuit IC is reduced in pressure by the injection expansion valve IE to an intermediate pressure, and flows into the internal heat exchanger 10. The liquid refrigerant that flows into the internal heat exchanger 10 exchanges heat with the liquid refrigerant flowing in the main circuit MC in the internal heat exchanger 10 and becomes gas refrigerant. This gas refrigerant flows into the intermediate pressure port P3 of the compressor 1.

[0053] The liquid refrigerant flowing through the main circuit MC is decompressed by the expansion valve 3 to become a low-pressure gas-liquid two-phase refrigerant, and flows out of the expansion valve 3. This gas-liquid two-phase refrigerant flows into the evaporator 4, where it is evaporated to become gas refrigerant. This gas refrigerant flows into the suction port P1 of the compressor 1.

[0054] Next, the effects of the second modification of the refrigeration cycle apparatus 100 according to the embodiment will be described.

[0055] According to the second modification of the refrigeration cycle apparatus 100 according to the embodiment, the internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing out of the condenser 2 and the refrigerant flowing out of the injection expansion valve IE in the injection circuit IC. Therefore, in the internal heat exchanger 10, heat exchange occurs between the refrigerant flowing out of the condenser 2 and the refrigerant flowing out of the injection expansion valve IE in the injection circuit IC, thereby improving the performance of the refrigeration cycle apparatus 100.

[0056] Furthermore, if the pipe diameter of the injection circuit IC is reduced due to an increase in the refrigerant flow rate in the injection circuit IC, the pressure loss increases. In this case, the temperature difference of the refrigerant in the internal heat exchanger 10 decreases, making heat exchange in the internal heat exchanger 10 difficult. In the second modification of the refrigeration cycle apparatus 100 according to the embodiment, the pipe diameter of the injection circuit IC is not reduced, so the pressure loss does not increase. Therefore, the temperature difference of the refrigerant in the internal heat exchanger 10 does not decrease, so heat exchange in the internal heat exchanger 10 is possible.

[0057] A third modification of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a refrigerant circuit diagram of the third modification of the refrigeration cycle apparatus 100 according to the embodiment. The third modification of the refrigeration cycle apparatus 100 according to the embodiment differs from the refrigeration cycle apparatus 100 according to the embodiment in the configuration of the branch portion I1 of the injection circuit IC.

[0058] The branch portion I1 has an upward portion UP and a downward portion DP. The downward portion DP is connected to the upward portion UP. The upward portion UP extends upward from the main circuit MC. The upward portion UP is connected to the main circuit MC. The downward portion DP extends downward from the upward portion UP. The height position of the downward portion DP is equal to or lower than the height position of the highest point of the upward portion UP.

[0059] Next, the effects of the third modification of the refrigeration cycle apparatus 100 according to the embodiment will be described.

[0060] According to the third modification of the refrigeration cycle apparatus 100 of the embodiment, the upward portion UP extends upward from the main circuit MC. This prevents refrigeration oil from exceeding the upper end of the upward portion UP and flowing into the downward portion DP. This prevents incompatible oil, which is refrigeration oil, from flowing into the injection circuit IC. This reduces the amount of incompatible oil, which is refrigeration oil, that flows into the injection circuit IC. This prevents incompatible oil, which is refrigeration oil, from accumulating in the injection circuit IC.

[0061] A fourth modification of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Fig. 5. Fig. 5 is a schematic perspective cross-sectional view of the upward portion UP of the branch portion I1 of the injection circuit IC in the fourth modification of the refrigeration cycle apparatus 100 according to the embodiment. Fig. 5 is a schematic perspective cross-sectional view showing a cross section perpendicular to the axial direction of the upward portion UP of the branch portion I1 of the injection circuit IC.

[0062] The upward portion UP has an inner wall surface IW. Grooves G are provided in the inner wall surface IW. In the fourth modification of the refrigeration cycle apparatus 100 according to the embodiment, the grooves G are provided around the entire circumference of the inner wall surface IW. In other words, a plurality of grooves G are provided continuously around the entire circumference of the inner wall surface IW. The grooves G extend in the vertical direction. In the fourth modification of the refrigeration cycle apparatus 100 according to the embodiment, the grooves G extend in a straight line in the vertical direction.

[0063] Next, the effects of the fourth modification of the refrigeration cycle apparatus 100 according to the embodiment will be described.

[0064] According to the fourth modification of the refrigeration cycle apparatus 100 of the embodiment, the grooves G provided on the inner wall surface IW of the upward portion UP extend in the vertical direction. Therefore, the incompatible oil, i.e., refrigerant oil, can move up the upward portion UP along the grooves G due to surface tension. This prevents the incompatible oil, i.e., refrigerant oil, from accumulating in the upward portion UP. This allows the incompatible oil, i.e., refrigerant oil, to flow from the upward portion UP to the downward portion DP, thereby preventing the incompatible oil, i.e., refrigerant oil, from accumulating in the injection circuit IC.

[0065] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0066] 1 Compressor, 2 Condenser, 3 Expansion valve, 4 Evaporator, 10 Internal heat exchanger, 20 Control device, 100 Refrigeration cycle device, DP Downward portion, G Groove, I1 Branch portion, I2 Confluence portion, IC Injection circuit, IE Injection expansion valve, IW Inner wall surface, MC Main circuit, UP Upward portion.

Claims

1. A refrigeration cycle device comprising: a main circuit having a compressor that compresses a refrigerant and discharges refrigerating machine oil together with the refrigerant, a condenser that condenses the refrigerant discharged from the compressor, an expansion valve that depressurizes the refrigerant flowing out from the condenser, and an evaporator that evaporates the refrigerant flowing out from the expansion valve; and an injection circuit having an injection expansion valve that depressurizes the refrigerant flowing out from the main circuit, and connected to the main circuit and an intermediate pressure side or a suction side of the compressor, wherein the refrigerating machine oil is an incompatible oil, and the injection circuit has, in the flow of the refrigerant, a branch portion that branches off from the main circuit and a junction portion that joins the main circuit, and the height position of the branch portion is higher than the height position of the junction portion.

2. A refrigeration cycle device as described in claim 1, further comprising an internal heat exchanger configured to exchange heat between the refrigerant flowing out of the condenser and the refrigerant flowing out of the injection expansion valve in the injection circuit.

3. A refrigeration cycle device as described in claim 1 or 2, which is configured to be able to select between a normal operation in which the refrigerant and the refrigeration oil flow through the main circuit and the injection circuit, and an oil recovery operation in which the refrigerant and the refrigeration oil flow through the main circuit and the injection circuit and the refrigeration oil is recovered in the compressor, and the opening degree of the injection expansion valve in the oil recovery operation is larger than the opening degree of the injection expansion valve in the normal operation.

4. A refrigeration cycle device as claimed in any one of claims 1 to 3, wherein the branching portion has an upward portion and a downward portion connected to the upward portion, the upward portion extending upward from the main circuit, and the downward portion extending downward from the upward portion.

5. A refrigeration cycle device according to claim 4, wherein the upwardly extending portion has an inner wall surface, a groove is provided in the inner wall surface, and the groove extends in the vertical direction.

6. When the injection circuit is connected to the intermediate pressure side of the compressor, the pressure at the branching portion is Pin, the pressure at the junction portion is Pout, the discharge pressure of the compressor is Pd, and the suction pressure of the compressor is Ps, Pin, Pout, Pd, and Ps are expressed as Pin / Pout>Pd / (Pd×Ps). １／２ The refrigeration cycle device according to any one of claims 1 to 5.

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