JP4964160B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus using an expander, and more particularly to a refrigeration cycle apparatus that supplies oil to an expander and a compressor that is driven by recovered power of the expander.

  Hereinafter, a conventional example in which the expansion energy of the working fluid is converted into mechanical energy and used to improve COP will be described. In the conventional example, an expander that converts expansion energy of working fluid into mechanical energy and a sub-compressor driven by the expander are housed in a single sealed container. A part of the refrigerant discharged from the main compressor is branched into the container to flow in, and the inside of the sealed container is kept at the same high pressure as the discharge pressure.

  Thereby, while reducing the viscosity of lubricating oil, sufficient quantity of lubricating oil can be supplied to the sliding part of an expander and a subcompressor with a differential pressure, and sealing performance can also be improved. Further, the sealed container is also used as a receiver tank for storing liquid refrigerant (for example, see Patent Document 1).

JP 2004-325018 A (Claim 2, FIG. 1 and the like)

In such a conventional refrigeration cycle apparatus, since the expander and the sub compressor driven by the expander relate to the circuit configuration of the two-stage compression in which the main compressor is disposed on the lower stage side, The oil supply method to the sub-compressor in the circuit configuration in which the machine is arranged on the high stage side has not been considered. In addition, when intermediate cooling is performed in a two-stage compression circuit, there is a problem that the refrigeration oil discharged from the low-stage compressor stays in the intermediate cooler and the heat transfer performance of the intermediate cooler is reduced. In particular, CO ₂ has a problem that the heat transfer performance with respect to the oil circulation rate is greatly reduced, and the efficiency (COP) of the refrigeration cycle is significantly reduced.

  Further, there is no means for separating the refrigerating machine oil discharged from the high-stage compressor, and there is a problem that the oil circulation rate in the main radiator increases and the performance decreases.

  The present invention was made to solve the problems of the conventional refrigeration cycle apparatus as described above, and in the refrigeration cycle apparatus using an expander, the oil separator and the oil return circuit are appropriately arranged in the refrigeration cycle. The purpose is to reduce the oil circulation rate and realize high-efficiency operation.

  The refrigeration cycle apparatus according to the present invention includes a first compressor, a first oil separator provided at an outlet of the first compressor, an expander, and a second compression driven by the recovered power of the expander. In the refrigeration cycle apparatus comprising a compressor, a load side heat exchanger, a first heat source side heat exchanger, and a second heat source side heat exchanger, the first compressor and the second compressor are connected in series. The second heat source side heat exchanger is connected between the first compressor and the second compressor, and the refrigeration oil separated by the first oil separator is connected to the second compressor. It is characterized in that it is supplied to.

  The refrigeration cycle apparatus according to the present invention is driven by the first compressor, the first oil separator provided at the outlet of the first compressor, the expander, and the recovery power of the expander. A second compressor, a second oil separator provided at an outlet of the second compressor, a load side heat exchanger, a first heat source side heat exchanger, and a second heat source side heat exchanger. In the refrigeration cycle apparatus provided, the first compressor and the second compressor are connected in series, and the second heat source side heat exchanger is interposed between the first compressor and the second compressor. And the refrigeration oil separated by the first oil separator or the second oil separator is supplied to the suction portion of the first compressor or the second compressor. is there.

  The refrigeration cycle apparatus according to the present invention includes a first compressor, a first oil separator provided at an outlet of the first compressor, an expander, and a second drive driven by recovered power of the expander. In the refrigeration cycle apparatus including a compressor, an evaporator, a first radiator, and a second radiator, the second compressor and the first compressor are connected in series, and the first The second radiator is connected between the compressor and the second compressor, and the refrigeration oil separated by the first oil separator is supplied to the second compressor. To do.

  According to the present invention, in the refrigeration cycle apparatus using the expander and the second compressor driven by the recovery power of the expander, the oil separator is properly disposed to reliably supply the oil to the second compressor, and the reliability A high refrigeration cycle apparatus can be provided.

Embodiment 1 FIG.
Hereinafter, the refrigeration cycle apparatus according to Embodiment 1 of the present invention will be described. FIG. 1 is a schematic diagram showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention.

  In the figure, the refrigeration cycle apparatus according to the present embodiment incorporates a first outdoor heat exchanger 3a that is a first heat source side heat exchanger and a second outdoor heat exchanger 3b that is a second heat source side heat exchanger. The outdoor unit 100 includes indoor units 200a and 200b that incorporate indoor heat exchangers 9a and 9b that are load-side heat exchangers, and a gas pipe 51 and a liquid pipe 52 that connect the outdoor unit 100 and the indoor units 200a and 200b. ing. For example, carbon dioxide that is in a supercritical state at a critical temperature (about 31 ° C.) or higher is sealed inside the refrigerant circuit.

  In the outdoor unit 100, the first compressor 1 for compressing the refrigerant gas, the first oil separator 60 provided at the outlet of the first compressor 1, and the operation modes of the indoor units 200a and 200b are selected. Four-way valve 2 and four-way valve 4 which are refrigerant flow path switching means for switching the direction of refrigerant flow, first outdoor heat exchanger 3a and second outdoor heat exchanger 3b which serve as a radiator or an evaporator according to the operation mode, expansion The expander unit 5 in which the machine 5a and the second compressor 5b are integrally formed, the oil discharge port 61 provided on the shell side surface of the expander unit 5, and the oil discharged from the oil discharge port 61 is the first compressor 1 Capillary tube 62 that is a decompression means for returning to the suction section, and a blower (not shown) for forcing the outside air to the outer surfaces of the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b are housed and installed outdoors. Is done.

  The first outdoor heat exchanger 3a is disposed between the four-way valve 2 and the four-way valve 4, and the second outdoor heat exchanger 3b is disposed between the first compressor 1 and the second compressor 5b during the cooling operation. Has been. Inside the expander unit 5, an expander 5a and a second compressor 5b are arranged, which are coaxially connected, and the internal pressure is maintained at approximately the same high pressure as the discharge pressure of the second compressor 5b. Yes. The expander unit 5 has a structure in which, for example, both the expander 5a and the second compressor 5b are constituted by a scroll type expander and a compressor, and the thrust direction load of the expander and the compressor is offset on both sides. Have. The second compressor 5b is provided with a bypass flow path, and a check valve 53 that is an on-off valve is provided in the bypass flow path. To match the refrigerant circulation flow rate and power of the expander 5a and the second compressor 5b, the upstream portion of the expander 5a has an open / close valve 6 (hereinafter referred to as a pre-expansion valve 6) in series and an open / close valve 7 (in parallel). Hereinafter, the bypass valve 7 is provided. Further, one end of the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b is connected via an electromagnetic valve 54 which is an on-off valve, and the other end is connected via an electromagnetic valve 55 which is an on-off valve. In addition, an electromagnetic valve 57 that is an on-off valve is provided in the piping from the outlet of the first compressor 1 to the second outdoor heat exchanger 3b, and the piping from the second outdoor heat exchanger 3b to the second compressor 5b is provided in the piping. An electromagnetic valve 58 that is an on-off valve is provided, and an electromagnetic valve 56 that is an on-off valve is provided in the bypass flow path of the second outdoor heat exchanger 3b.

  The indoor units 200a and 200b include indoor heat exchangers 9a and 9b that are load-side heat exchangers, electronic expansion valves 8a and 8b that can change the opening to adjust the refrigerant flow rate to the indoor heat exchangers 9a and 9b, A blower (not shown) for forcing air to the outer surfaces of the indoor heat exchangers 9a and 9b and a pipe for connecting them are incorporated. One end of the indoor heat exchangers 9a and 9b is connected to the gas pipe 51, and the other end is connected to the liquid pipe 52 via the electronic expansion valves 8a and 8b. In this embodiment, two indoor units 200a and 200b are used, but it goes without saying that one or three or more indoor units may be used.

  The operation of the refrigeration cycle apparatus configured as described above will be described. First, the case where the cooling operation is performed will be described with reference to FIGS. 1 and 2. FIG. 2 shows the refrigerant state of symbols A to H shown in the refrigerant circuit of FIG. 1 on the Ph diagram. In the cooling operation, the four-way valve 2 in the outdoor unit 100 is set so that the first port 2a and the second port 2b communicate with each other, and the third port 2c and the fourth port 2d communicate with each other. 4a and 4th opening 4d are connected, and 2nd opening 4b and 3rd opening 4c are set so that it may connect (solid line in FIG. 1). The pre-expansion valve 6 is fully opened, the bypass valve 7 is fully closed, and the electronic expansion valves 8a and 8b are fully opened. The solenoid valve 56 is closed and the solenoid valves 57 and 58 are opened. In this case, the basic decompression function is realized by the expander 5a, and an electronic device is obtained so that an appropriate degree of superheat (for example, 5 to 10 ° C.) set in advance at the outlets of the indoor heat exchangers 9a and 9b is obtained. The expansion valves 8a and 8b are adjusted.

  At this time, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 1 flows into the first oil separator 60, and the refrigerating machine oil that flows out from the compressor accompanying the gas refrigerant flows into the first oil separator 60. Separated within. The oil separated by the first oil separator 60 is supplied to the suction portion of the second compressor and supplied to the second compressor. The oil supplied to the second compressor 5b is returned to the suction portion of the first compressor from the oil discharge port 61 provided on the side surface of the expander unit 5 through the capillary tube 62 serving as a decompression unit. Since the solenoid valve 56 is closed, the refrigerant that has passed through the first oil separator 60 (state A) passes through the solenoid valve 57 and is radiated to some extent by the second outdoor heat exchanger 3b to be cooled (state B). ) And flows into the second compressor 5b. At this time, the electromagnetic valves 54 and 55 connecting the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b are closed. The refrigerant that has passed through the electromagnetic valve 58 and has flowed into the second compressor 5b driven by the expander 5a is compressed by an amount commensurate with the power recovered by the expander. At this time, the check valve 53 provided in the bypass flow path of the second compressor 5b is in an open state at the time of startup where no pressure difference occurs, but when the expander 5a operates and the second compressor 5b is driven. The second compressor is closed by the high and low pressure difference. The refrigerant discharged from the second compressor 5b passes through the second port 2b from the first port 2a of the four-way valve 2 (state C) and dissipates heat to the air that is the heating medium in the first outdoor heat exchanger 3a. (State D) flows from the second port 4b of the four-way valve 4 to the pre-expansion valve 6 through the third port 4c. The refrigerant (state E) whose inlet density of the expander 5a is adjusted by the pre-expansion valve 6 is depressurized by the expander 5a, passes through the first port 4a to the fourth port 4d of the four-way valve 4 and passes through the liquid pipe 52. Pass (state F). At this time, the bypass valve 7 of the expander 5a is controlled so that the refrigerant flow rate and the recovered power passing through the second compressor 5b are balanced. Thereafter, the refrigerant is slightly depressurized by the decompression means 8a and 8b in the indoor units 200a and 200b (state G). After the heat load in the air-conditioning target space is processed by the indoor heat exchangers 9a and 9b, the refrigerant flows into the gas pipe 51. The four-way valve 2 flows from the fourth port 2d through the third port 2c into the first compressor 1 (state H). At this time, when the outlet portion of either the indoor heat exchanger 9a or the indoor heat exchanger 9b does not reach the set superheat degree (for example, 5 to 10 ° C.), the decompression means 8a and 8b include the indoor heat exchanger 9a, The outlet superheat degree of 9b is adjusted to be the same.

  Next, the heating operation will be described with reference to FIGS. 1 and 3. In the present embodiment, an example in which the expander is used also during the heating operation is shown. However, since the density ratio between the inlet portion of the expander 5a and the inlet portion of the second compressor 5b increases during the heating operation, In the same volume ratio, the power recovery loss for balancing the refrigerant circulation flow rate and the recovered power becomes large. Therefore, it is good also as a circuit structure which abolishes the four-way valve 4 as needed and does not use the expander unit 5 at the time of heating operation.

  In the heating operation in the present embodiment, the four-way valve 2 inside the outdoor unit 100 is set so that the first port 2a and the fourth port 2d communicate with each other, and the second port 2b and the third port 2c communicate with each other. 4 is set such that the first port 4a and the second port 4b communicate with each other and the third port 4c and the fourth port 4d communicate with each other (dotted line). Further, the electromagnetic valves 54 and 55 are opened, and the electromagnetic valves 57 and 58 are closed. In this case, the electronic expansion valves 8a and 8b in the indoor units 200a and 200b are fully opened, and the basic pressure reducing function is realized by the expander 5a. When the amount of decompression is insufficient, the electronic expansion valves 8a and 8b are provided so that an appropriate degree of supercooling (for example, 5 to 15 ° C.) set in advance at both outlets of the indoor heat exchangers 9a and 9b can be obtained. Adjusted. Here, the degree of supercooling in the case of carbon dioxide indicates the difference between the virtual saturation temperature (for example, the temperature determined by the enthalpy and operating pressure at the critical point) and the outlet temperature of the indoor heat exchangers 9a and 9b. .

  At this time, the refrigerant (state A) compressed in the first compressor 1 and in a high temperature and high pressure supercritical state flows into the first oil separator 60, and the refrigerating machine oil that flows out along with the gas refrigerant is the first. It is separated in the oil separator 60. The oil separated by the first oil separator 60 is supplied to the suction portion of the second compressor 5b, and is supplied to the second compressor 5b. The oil supplied to the second compressor is returned to the suction portion of the first compressor from the oil discharge port 61 provided on the side surface of the expander unit 5 through the capillary tube 62 serving as a decompression unit. Since the solenoid valves 57 and 58 are closed, the refrigerant that has passed through the first oil separator 60 passes through the solenoid valve 56 and the pressure slightly decreases (state B), and is further compressed by the second compressor 5b. Then, the air flows into the indoor units 200a and 200b from the first port 2a of the four-way valve 2 through the fourth port 2d and the gas pipe 51. The high-temperature and high-pressure refrigerant that has flowed into the indoor units 200a and 200b flows into the indoor heat exchangers 9a and 9b, dissipates heat to indoor air (not shown), heats the room, and itself decreases in temperature (state G). This medium-temperature and high-pressure refrigerant passes through the electronic expansion valves 8 a and 8 b (state F) and flows into the liquid pipe 52. The refrigerant that has flowed into the liquid pipe 52 passes through the fourth port 4 d and the third port 4 c of the four-way valve 4 and flows into the pre-expansion valve 6. The refrigerant flowing out of the pre-expansion valve 6 (state E) flows into the expander 5a, passes through the first port 4a and the second port 4b of the four-way valve 4 (state D), and the electromagnetic valves 54 and 55 are open. Therefore, it flows into the first and second outdoor heat exchangers 3a and 3b. Thereafter, the gas refrigerant (state C) evaporated in the first and second outdoor heat exchangers 3a and 3b passes from the second port 2b of the four-way valve 2 to the third port 2c, and the suction portion (state) of the first compressor 1 Return to H).

  In the present embodiment, the four-way valve 2 and the on-off valves 54, 55, 56, 57, 58 are provided in the refrigerant circuit, and the first heat source side heat exchanger is set to a high pressure and the second heat source side heat exchanger is set to a high pressure during cooling operation. Use the second heat source side heat exchanger for both cooling and heating operations by operating at an intermediate pressure and operating both the first heat source side heat exchanger and the second heat source side heat exchanger at low pressure during heating operation. And a highly efficient refrigeration cycle apparatus can be obtained.

  Here, the detailed structure of the expander unit 5 is shown in FIG. FIG. 4 shows an expander unit that employs a scroll structure for both the expander 5a and the second compressor 5b. The expander 5a is composed of an expander fixed scroll 351 and an expander swinging scroll 352. The compressor 5 b includes a second compressor fixed scroll 361 and a second compressor swing scroll 362. A shaft 308 passes through the center of these scrolls, and balance weights 309a and 309b are provided at both ends of the shaft 308. The shaft 308 includes an expander bearing 351b and a second compressor bearing 361b. It is supported by. Further, the back surface of the swing scroll 352 of the expander 5a and the back surface of the swing scroll 362 of the second compressor 5b have a back-to-back structure. In addition, an Oldham ring 307 and a crank portion 308 b which are necessary parts are provided, and these are all stored in the hermetic container 310.

  In the expander unit 5 having such a structure, if the volume ratio of the expander and the second compressor (hereinafter referred to as the expansion pressure volume ratio) is designed to be large (for example, 2.3 or more), the second tooth is used at the same tooth height. Since the thrust load from the expander 5a side becomes smaller than the thrust load from the compressor 5b and the thrust load cannot be canceled on both sides, the expander unit in which the second compressor 5b and the expander 5a are integrated. The configuration of 5 becomes difficult. Further, in order to reduce the thrust load on the second compressor 5b side, it is possible to make the second compressor 5b side a spiral having an extremely high tooth height, but this causes a problem in strength. Therefore, in the expander unit having the scroll structure for both the expander 5a and the second compressor 5b, by setting the expansion / compression volume ratio in the range of 2.3 or less, for example, not only in terms of performance but also in terms of structure, reliability A high expander unit can be configured.

  Next, a method for controlling the expander 5a will be described. In the present embodiment, the pre-expansion valve 6 provided in series with the expander 5a at the inlet of the expander 5a and the bypass valve 7 provided so as to bypass the expander 5a are used, and the flow rate passing through the expander 5a. And the expander 5a is controlled so that the collect | recovered motive power and the flow volume and motive power which pass the 2nd compressor 5b correspond. In addition, since the bypass flow path for bypassing the second compressor is provided and the on-off valve is provided in the bypass flow path, the refrigerant can surely flow in the refrigerant circuit even at the start-up when the second compressor does not operate.

  Next, the relationship between the oil circulation rate and the heat transfer rate in the radiator (gas cooler) will be described. FIG. 5 shows the relationship between the oil circulation rate and the heat transfer rate. The unit of the oil circulation rate on the horizontal axis is% by weight. The heat transfer rate suddenly decreases from around 0.3% of the oil circulation rate, and the heat transfer rate of 1% oil circulation rate becomes 1/2 or less than that of 0.1% oil circulation rate. Therefore, by reducing the oil circulation rate in the radiator, the heat transfer rate can be improved and the operation efficiency of the refrigeration cycle can be improved. In the present embodiment, the oil discharged from the first compressor is separated by the first oil separator 60 installed at the outlet of the first compressor, and the oil circulation rate in the second outdoor heat exchanger 3b is set. Since it can reduce, the 2nd outdoor heat exchanger 3b can be used efficiently, and a highly efficient refrigerating-cycle apparatus can be provided. Here, even if the oil separation efficiency of the first oil separator 60 is generally low, it is about 90%, and the oil circulation rate in the refrigerant discharged from the first compressor is about 2% to the oil circulation rate about 0.2%. It is possible to reduce.

  Moreover, in this Embodiment, although the 1st oil separator 60 is not provided in the exit part of the 2nd compressor 5b, generally the boosting work of the 2nd compressor 5b is compared with the boosting work of the 1st compressor 1. The oil discharge amount is also small. Therefore, even when no oil separator is provided at the outlet of the second compressor 5b, the oil circulation rate of the first outdoor heat exchanger 3a can be kept low, and a highly efficient refrigeration cycle apparatus can be provided. .

  Further, since the oil separated by the first oil separator 60 returns to the suction portion of the second compressor 5b and is sucked into the second compressor 5b, the oil can be reliably supplied to the expander unit 5, and reliability is improved. A high refrigeration cycle apparatus can be provided. Further, the oil discharge port 61 is provided in the body portion of the second compressor 5b so that the refrigeration oil in the second compressor 5b is returned to the suction portion of the first compressor 1, so that the first compression Oil can be reliably returned to the machine.

  In the present embodiment, an example in which the expander is used for both the cooling operation and the heating operation using the four-way valve 4 has been shown, but the expander 5a may be used only during the cooling operation. In that case, the second port 4b and the third port 4c, the first port 4a and the fourth port 4d of the four-way valve 4 are respectively connected by piping, and the four-way valve 4 becomes unnecessary. At this time, a refrigerant circuit that recovers power using the expander 5a during the cooling operation is configured, and a refrigerant circuit that does not recover power is configured using the bypass valve of the expander 5a during the heating operation.

  Moreover, in this Embodiment, although the structure shown in FIG. 4 was shown as an example of the expander 5a, it is not restricted to this, A relief valve is provided in the flow path which bypasses the expansion mechanism entrance / exit part inside the expander 5a. The relief valve may be opened when the pressure difference between the front and rear of the expander 5a is a predetermined value or more. In this case, when the pressure difference is equal to or larger than the predetermined pressure difference, the relief valve is opened, so that the refrigerant circulation amount passing through the expander is automatically adjusted according to the pressure difference, and the electronic expansion valve provided outside the expander 5a is It becomes unnecessary.

  As described above, since the oil separated by the first oil separator 60 installed at the outlet of the first compressor 1 is reliably supplied to the second compressor 5b, a highly reliable refrigeration cycle apparatus is provided. can do. Further, since the oil discharge port is provided in the body portion of the second compressor 5b, and the refrigeration oil in the second compressor 5b is returned to the suction portion of the first compressor 1, the first compressor Can improve the reliability. Moreover, since it can prevent that the refrigeration oil discharged from a 1st compressor flows in into the 2nd outdoor heat exchanger 3b which is an intercooler, a highly efficient refrigeration cycle apparatus can be obtained.

  In addition, since a bypass flow path that bypasses the second compressor 5b is provided and a check valve 53 that is an on-off valve is provided in the bypass flow path, the refrigerant flow rate can be reliably ensured even when the second compressor 5b does not operate. It can flow. Also, four-way valves and on-off valves 54, 55, 56, 57, and 58 are provided. During the cooling operation, the first heat source side heat exchanger is operated at a high pressure, and the second heat source side heat exchanger is operated at an intermediate pressure to perform a heating operation. Sometimes the first heat source side heat exchanger and the second heat source side heat exchanger are operated at a low pressure, so that the second heat source side heat exchanger can be used for both cooling and heating operations, and a highly efficient refrigeration cycle. A device can be obtained. Since both the expander and the second compressor have an integrated configuration in which the scroll-type rear surfaces are combined, a compact expander unit 5 can be configured. Furthermore, since carbon dioxide having a large expansion power recovery effect is used as the refrigerant, the oil circulation rate is reduced in the intermediate cooler corresponding to the second outdoor heat exchanger 3b and the radiator corresponding to the first outdoor heat exchanger 3a. The effect is increased.

Embodiment 2. FIG.
Hereinafter, a refrigeration cycle apparatus according to Embodiment 2 of the present invention will be described. FIG. 6 is a schematic diagram showing a refrigeration cycle apparatus according to Embodiment 2 of the present invention. The difference from Embodiment 1 is that a second oil separator 63 is provided at the outlet of the second compressor 5b. The oil separated by the second oil separator 63 is returned to the suction portion of the second compressor 5b through the capillary tube 64 as decompression means. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  Next, the operation during the cooling operation will be described. The electromagnetic valves 54 and 55 and the electromagnetic valve 56 installed between the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b are closed, and the electromagnetic valves 57 and 58 are opened. At this time, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 1 flows into the first oil separator 60, and the refrigerating machine oil that flows out along with the gas refrigerant is separated in the first oil separator 60. The The oil separated by the first oil separator 60 is supplied to the suction portion of the second compressor 5b, and is supplied to the second compressor 5b. The oil supplied to the second compressor 5b is returned to the suction portion of the first compressor from the oil discharge port 61 provided on the side surface of the expander unit 5 through the capillary tube 62 serving as a decompression unit. Since the solenoid valve 56 is closed, the refrigerant that has passed through the first oil separator 60 passes through the solenoid valve 57, is cooled by being dissipated to some extent in the second outdoor heat exchanger 3b, and passes through the solenoid valve 58. And flows into the second compressor 5b. The refrigerant that has flowed into the second compressor 5b is compressed by an amount commensurate with the power recovered by the expander 5a. The refrigerant discharged from the second compressor 5 b flows into the second oil separator 63, and the refrigeration oil that has flowed out along with the gas refrigerant is further separated in the second oil separator 63. The oil separated by the second oil separator 63 is supplied to the suction portion of the second compressor 5b via the capillary 64, which is a decompression means, and is supplied to the second compressor 5b. The refrigerant that has passed through the second oil separator 63 passes through the first port 2a of the four-way valve 2 through the second port 2b and radiates heat to the air that is the medium to be heated in the first outdoor heat exchanger 3a. From the second port 4b to the pre-expansion valve 6 through the third port 4c. Since the refrigerant flow from passing through the pre-expansion valve 6 to the suction of the first compressor 1 is the same as that in the first embodiment, detailed description thereof is omitted, and the description of the operation operation during heating is also omitted.

  In the present embodiment, in addition to the effects of the first embodiment, the refrigerating machine oil discharged from the second compressor 5b is further separated by the second oil separator 63 and supplied to the second compressor 5b. Oil can be reliably supplied to the compressor 5b. Moreover, it can prevent reliably that refrigeration oil flows in into the 1st outdoor heat exchanger 3a which is a heat radiator, and can obtain a highly efficient refrigerating-cycle apparatus. In the present embodiment, the return pipe from the second oil separator 63 is joined with the return pipe of the first oil separator 60 and connected to the suction portion of the second compressor 5b. It is good also as a structure connected to 1 suction | inhalation part.

  As described above, in the present embodiment, in addition to the effects of the first embodiment, the refrigeration oil discharged from the second compressor 5b is separated by the second oil separator 63 and reliably returned to the second compressor 5b. The refrigeration oil can be prevented from flowing not only into the intermediate cooler but also into the radiator, and a highly efficient refrigeration cycle apparatus can be obtained.

Embodiment 3 FIG.
Hereinafter, a refrigeration cycle apparatus according to Embodiment 3 of the present invention will be described. FIG. 7 is a schematic diagram showing a refrigeration cycle apparatus according to Embodiment 3 of the present invention. The difference between Embodiment 1 and Embodiment 2 is the first oil separator 60 and the second oil separator 63. The separated refrigeration oil is returned to the suction portions of the first compressor 1 and the second compressor 5b, respectively, and to the suction portion of the first compressor 1 from an oil discharge port 61 provided on the shell side surface of the expander unit 5. It is the point which made it the structure which returns refrigeration oil. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  Next, the operation during the cooling operation will be described. The electromagnetic valves 54 and 55 and the electromagnetic valve 56 installed between the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b are closed, and the electromagnetic valves 57 and 58 are opened. At this time, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 1 flows into the first oil separator 60, and the refrigerating machine oil that flows out along with the gas refrigerant is separated in the first oil separator 60. The The oil separated by the first oil separator 60 returns to the suction portion of the first compressor 1 through the capillary tube 62 that is a decompression means, and is refueled to the first compressor. Since the solenoid valve 56 is closed, the refrigerant that has passed through the first oil separator 60 passes through the solenoid valve 57, is cooled by being radiated to some extent by the second outdoor heat exchanger 3b, and passes through the solenoid valve 58. It flows into the second compressor 5b. The refrigerant that has passed through the electromagnetic valve 58 and has flowed into the second compressor 5b driven by the expander 5a is compressed by an amount commensurate with the power recovered by the expander. The refrigerant discharged from the second compressor 5 b flows into the second oil separator 63, and the refrigeration oil that has flowed out along with the gas refrigerant is separated within the second oil separator 63. The oil separated by the oil separator 63 returns to the suction portion of the second compressor 5b through the capillary 64, which is a decompression means, and is refueled to the second compressor 5b. The oil supplied to the second compressor 5b is returned to the suction portion of the first compressor 5b from the oil discharge port 61 provided on the side surface of the expander unit 5 through the capillary 65 serving as a decompression unit. The refrigerant that has passed through the second oil separator 63 passes through the first port 2a of the four-way valve 2 through the second port 2b and radiates heat to the air that is the medium to be heated in the first outdoor heat exchanger 3a. From the second port 4b to the pre-expansion valve 6 through the third port 4c. Since the refrigerant flow from passing through the pre-expansion valve 6 to the suction of the first compressor 1 is the same as that in the first embodiment, detailed description thereof is omitted, and the description of the operation operation during heating is also omitted.

  Here, the relationship between the oil separation efficiency of the first oil separator 60 and the second oil separator 63 will be described. When the oil circulation rate at the outlet portion of the first oil separator 60 is Gro1 (%) and the oil circulation rate at the outlet portion of the second oil separator 63 is Gro2 (%), the oil level of the second compressor 5b does not decrease. Since the inflow flow rate of the refrigerating machine oil is larger than the outflow flow rate, Gro2 ≦ Gro1 needs to be satisfied even when the flow rate of oil returned from the oil discharge port 61 through the capillary 65 is zero. For example, when the oil circulation rate at the outlet portion of the first compressor 1 and the oil circulation rate at the outlet portion of the second compressor are equal, in order to satisfy Gro2 ≦ Gro1, the first provided at the outlet portion of the first compressor It is necessary to make the oil separation efficiency of the oil separator 60 lower than the oil separation efficiency of the second oil separator 63 provided at the outlet of the second compressor. When the oil separation efficiency of the first oil separator 60 is higher than the oil separation efficiency of the second oil separator 63, the oil level in the second compressor 5b is lowered, and there is a possibility that the oil will be exhausted. In the present embodiment, since the oil separation efficiency of the second oil separator 63 is higher than the oil separation efficiency of the first oil separator 60, the oil level of the expander unit 5 does not decrease. A highly reliable refrigeration cycle apparatus can be provided.

  As mentioned above, in this Embodiment, in addition to the effect of Embodiment 1, since the 2nd oil separator 63 was provided, the 1st outdoor heat exchanger whose refrigerating machine oil discharged from the 2nd compressor 5b is a radiator. The flow into 3a can be prevented, and a highly efficient refrigeration cycle apparatus can be obtained. Moreover, since the 1st and 2nd oil separator is comprised so that the oil separation efficiency of the 2nd oil separator 63 may become higher than the oil separation efficiency of the 1st oil separator 60, the 2nd compressor 5b It is possible to provide a highly reliable refrigeration cycle apparatus without lowering the oil level inside.

Embodiment 4 FIG.
Hereinafter, a refrigeration cycle apparatus according to Embodiment 4 of the present invention will be described. FIG. 8 is a schematic diagram showing a refrigeration cycle apparatus according to Embodiment 4 of the present invention. Unlike the first embodiment, the first and second outdoor heat exchangers 3a and 3b are water heat exchangers (hereinafter referred to as radiators), and the indoor heat exchanger 9 is an outdoor heat exchanger (hereinafter referred to as an evaporator). This is an example of a water heater. The specific difference from the first embodiment is that the four-way valves 2 and 4 are not provided, and that the first outdoor heat exchanger 3a and the second outdoor heat exchanger 3b are changed to water and refrigerant heat exchangers. The point that operates as a radiator, the indoor heat exchanger is changed to an outdoor heat exchanger, and operates as an evaporator. Similarly to the third embodiment, the second oil separator 63 is provided, and the oil separated by the first oil separator 60 and the second oil separator 63 is sucked into the first compressor 1 and the second compressor 5b. It returns to the suction section of the first compressor 1 from the oil drain port 61 provided on the side surface of the shell of the expander unit 5. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  The operation during hot water supply will be described. The pre-expansion valve 6 is opened and the bypass valve 7 is closed. At this time, the high-temperature and high-pressure gas refrigerant discharged from the first compressor 1 flows into the first oil separator 60, and the refrigerating machine oil that flows out along with the gas refrigerant is separated in the first oil separator 60. The The oil separated by the first oil separator 60 returns to the suction portion of the first compressor 1 through the capillary tube 62 that is a decompression means, and is refueled to the first compressor. The refrigerant that has passed through the first oil separator 60 is cooled by being radiated to some extent by the second radiator 3b and flows into the second compressor 5b. The refrigerant that has flowed into the second compressor 5b is compressed by an amount commensurate with the power recovered by the expander. The refrigerant discharged from the second compressor 5 b flows into the second oil separator 63, and the refrigeration oil that has flowed out along with the gas refrigerant is separated within the second oil separator 63. The oil separated by the oil separator 63 is returned to the suction portion of the second compressor 5b through the capillary 64, which is a decompression means, and is refueled to the second compressor 5b. The oil supplied to the second compressor 5b is returned to the suction portion of the first compressor 5b from the oil discharge port 61 provided on the side surface of the expander unit 5 through the capillary 65 serving as a decompression unit. The refrigerant that has passed through the second oil separator 63 dissipates heat to the water to be heated by the first radiator 3a, and flows into the pre-expansion valve 6 because the bypass valve 7 is closed. The refrigerant whose inlet density of the expander 5 a is adjusted by the pre-expansion valve 6 is decompressed by the expander 5 a and passes through the liquid pipe 52. The refrigerant that has passed through the liquid pipe 52 collects heat from the air by the evaporator 9, evaporates itself, passes through the gas pipe 51, and returns to the first compressor 1.

  By such an operation, water is heated by receiving heat from the refrigerant in the first radiator 3a and the second radiator 3b, and high-temperature water is supplied. At this time, the water circuit (not shown in FIG. 8) flowing through the first radiator 3a and the second radiator 3b may have any configuration such as series or parallel, and the first oil separator 60 And the oil separation effect of the 2nd oil separator 63 is exhibited similarly.

  As described above, in the present embodiment, in addition to the effects of the first embodiment, the refrigerating machine oil discharged from the first compressor 1 and the second compressor 5b can be prevented from flowing into the first and second radiators. There is an effect that a highly efficient refrigeration cycle apparatus can be obtained.

It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the operation | movement of the air_conditionaing | cooling operation on the Ph diagram which concerns on Embodiment 1 of this invention. It is a figure which shows the operation | movement of the heating operation on the Ph diagram which concerns on Embodiment 1 of this invention. It is a figure which shows the cross section of the expander which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship of the heat transfer rate with respect to the oil circulation rate which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 4 of this invention.

Explanation of symbols

  1 first compressor, 2, 4 four-way valve, 3a, 3b outdoor heat exchanger (heat radiator), 5 expander unit, 5a expander, 5b second compressor, 6, 7, 8a, 8b electronic expansion valve, 9 indoor heat exchanger (evaporator), 9a, 9b indoor heat exchanger, 51 gas piping, 52 liquid piping, 53 check valve, 54, 55, 56, 57, 58 solenoid valve, 61 oil outlet, 60, 63 Oil separator, 62, 64, 65 Capillary tube, 100 Outdoor unit, 200a, 200b Indoor unit, 307 Oldham ring, 308 shaft, 308b Crank part, 309a, 309b Balance weight, 310 Airtight container, 312 Second compressor suction pipe 313 Expander suction pipe, 314 Second compressor discharge pipe, 315 Expander discharge pipe, 351 Expander fixed scroll, 351b Expander bearing, 352 Expansion YoYurado scroll, 361 second compressor fixed scroll, 361b second compressor bearing portion, 362 a second compressor orbiting scroll.

Claims (9)

A first compressor, a first oil separator provided at an outlet of the first compressor, an expander, a second compressor driven by recovered power of the expander, and a load-side heat exchanger In the refrigeration cycle apparatus including the first heat source side heat exchanger,
The first compressor and the second compressor are connected in series, and the refrigeration oil separated by the first oil separator is supplied to the second compressor,
A second heat source side heat exchanger is connected between the first compressor and the second compressor;
The first oil separator is disposed on the outlet side of the first compressor during cooling operation and on the inlet side of the second heat source side heat exchanger ,
A four-way valve is provided, the first heat source side heat exchanger is operated at a high pressure during the cooling operation, the second heat source side heat exchanger is operated at an intermediate pressure, and the first heat source side heat exchanger and the second heat source side heat are operated during the heating operation. Both exchangers operate as low pressure,
The inlet / outlet of the second heat source side heat exchanger is branched into two, one end on the inlet side to the discharge part of the first compressor, and the other end on the inlet side to the liquid pipe side of the first heat source side heat exchanger The refrigeration cycle apparatus is characterized in that one end on the outlet side is connected to the suction portion of the second compressor, and the other end on the outlet side is connected to the gas pipe side of the first heat source side heat exchanger .   An oil discharge port is provided in a body portion of the second compressor, and refrigerating machine oil in the second compressor is returned to the suction portion of the first compressor or the second compressor. The refrigeration cycle apparatus according to claim 1.   3. The refrigeration cycle according to claim 1, wherein a decompression unit is provided between an oil discharge port of the second compressor and a suction portion of the first compressor or the second compressor. apparatus.   The second oil separator is provided at an outlet portion of the second compressor, and the oil separated by the second oil separator is supplied to the suction portion of the first or second compressor. The refrigeration cycle apparatus according to any one of 1 to 3. A first compressor; a first oil separator provided at an outlet of the first compressor; an expander; a second compressor driven by recovered power of the expander; and the second compressor In the refrigeration cycle apparatus provided with the second oil separator, the load side heat exchanger, and the first heat source side heat exchanger provided at the outlet of
The first compressor and the second compressor are connected in series,
One of the refrigerating machine oil separated by the first oil separator and the refrigerating machine oil separated by the second oil separator is one of the first compressor and the second compressor. While being supplied to the suction unit, the other refrigerating machine oil is supplied to the other suction unit, or both refrigerating machine oils are supplied to one suction unit of the first compressor and the second compressor,
A second heat source side heat exchanger is connected between the first compressor and the second compressor;
The first oil separator is disposed on the outlet side of the first compressor during cooling operation and on the inlet side of the second heat source side heat exchanger ,
A four-way valve is provided, the first heat source side heat exchanger is operated at a high pressure during the cooling operation, the second heat source side heat exchanger is operated at an intermediate pressure, and the first heat source side heat exchanger and the second heat source side heat are operated during the heating operation. Both exchangers operate as low pressure,
The inlet / outlet of the second heat source side heat exchanger is branched into two, one end on the inlet side to the discharge part of the first compressor, and the other end on the inlet side to the liquid pipe side of the first heat source side heat exchanger The refrigeration cycle apparatus is characterized in that one end on the outlet side is connected to the suction portion of the second compressor, and the other end on the outlet side is connected to the gas pipe side of the first heat source side heat exchanger .   The first and second oil separators are configured so that the oil separation efficiency of the second oil separator is higher than the oil separation efficiency of the first oil separator. The refrigeration cycle apparatus described.   An oil discharge port is provided in a body portion of the second compressor, and refrigerating machine oil in the second compressor is supplied to the suction portion of the first compressor or the second compressor. The refrigeration cycle apparatus according to claim 5 or 6.   8. The pressure reducing means is provided between the oil outlet of the second compressor and the suction pipe of the first compressor or the second compressor. 8. The refrigeration cycle apparatus described in 1. The refrigeration cycle apparatus according to any one of claims 1 to 8, wherein an on-off valve is provided at each of an outlet and an inlet branched into two of the second heat source side heat exchanger .

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