JP2014196874A - Refrigeration cycle device and air conditioner including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device capable of solving unevenness of quantities of oil held in a plurality of compressors and ensuring an oil level necessary for each compressor, and an air conditioner including the same.SOLUTION: A refrigeration cycle device 2 including a plurality of compressors 10 and 30 connected to a refrigerant circuit in parallel, comprises an oil equalization pipe 55 connecting the compressors 10 and 30 to each other to communicate an internal space of the compressor 10 with that of the compressor 30, and circulating refrigerating machine oil between the compressors 10 and 30; and a valve 55a provided in the oil equalization pipe 55 and opening/closing the oil equalization pipe 55.

Description

  The present invention relates to a refrigeration cycle apparatus in which a plurality of compressors are connected in parallel and an air conditioner including the refrigeration cycle apparatus.

  In a multi-chamber multi-type air conditioner having a capacity of 10 HP or more, a plurality of compressors are connected in parallel to the refrigeration cycle, and each compressor is often operated under the same control. However, since minute differences in operating conditions occur in each compressor, the amount of refrigerating machine oil taken out from each compressor is slightly different. As a result, the amount of oil retained in each compressor is unevenly distributed, and it is easy for some compressors to suffer from problems due to insufficient refrigeration oil.

  Patent Document 1 discloses a refrigeration cycle apparatus in which an oil separator is disposed on the discharge side of a compressor and an oil return pipe connects between the oil separator and the suction side of the compressor. In this refrigeration cycle apparatus, the refrigeration oil discharged together with the refrigerant from the compressor is separated from the refrigerant in the oil separator, flows into the suction side piping of the compressor through the oil return pipe, and circulates in the refrigeration cycle. At the same time, it returns to the compressor.

  Patent Document 2 discloses an air conditioner in which a connection pipe attached to the lower part of each compressor is raised above the oil level in the compressor and the ends of the connection pipes of the two compressors are connected to each other with an oil equalizing pipe. A machine is disclosed. In this air conditioner, the oil level in each compressor is adjusted by a soaking operation performed in parallel with the air conditioning operation.

JP 2004-293822 A Japanese Utility Model Publication No. 6-40947

  However, in the refrigeration cycle apparatus disclosed in Patent Document 1, refrigeration oil discharged from each compressor is returned into each compressor via an oil separator, an oil return pipe, and a suction side pipe. There is a problem that it takes a long time to eliminate the uneven distribution of the amount of oil retained. In addition, there is a problem that the uneven distribution of the retained oil amount occurring in the stopped compressor cannot be resolved by the next start-up. In particular, after a one-side operation is performed in which only a part of a plurality of compressors (for example, only one of two compressors) is operated, or a plurality of compressors are operated at different frequencies. After that, it was difficult to ensure the required oil level in each compressor.

  Furthermore, in the air conditioner disclosed in Patent Document 2, since the lower portions of the two compressors are connected to each other via an oil equalizing pipe, the compression of the other compressor is reduced when the oil level of one compressor is lowered. The oil level of the machine may also drop to the bottom. As a result, the required oil level cannot be ensured by both of the two compressors, and there is a problem that a malfunction due to a shortage of refrigeration oil is likely to occur in both compressors.

  The present invention has been made in order to solve at least one of the above-described problems, and can eliminate the uneven distribution of the amount of oil retained by a plurality of compressors, as well as the oil level required for each compressor. An object of the present invention is to provide a refrigeration cycle apparatus and an air conditioner equipped with the same.

  The refrigeration cycle apparatus according to the present invention is a refrigeration cycle apparatus including a plurality of compressors connected in parallel, wherein the compressors are connected to communicate with each other in an internal space of the compressors. It has an oil equalization pipe which distributes refrigerating machine oil, and a valve which opens and closes the oil equalization pipe.

  According to the present invention, since the oil equalizing pipe for circulating the refrigeration oil between the compressors is provided, the uneven distribution of the retained oil amount of the plurality of compressors can be eliminated. Further, according to the present invention, since the valve for opening and closing the oil equalizing pipe is provided, it is possible to ensure the oil level required for each compressor.

It is a refrigerant circuit diagram which shows schematic structure of the refrigerating-cycle apparatus 2 which concerns on Embodiment 1 of this invention, and the air conditioner 1 provided with the same. It is a refrigerant circuit diagram which shows the refrigerant circuit from an evaporator to a condenser as a principal part structure of the refrigerating-cycle apparatus 2 which concerns on Embodiment 1 of this invention. It is a refrigerant circuit diagram which shows the principal part structure of the refrigerating-cycle apparatus which is not provided with the oil equalizing pipe 55 and the valve | bulb 55a as a comparative example of the refrigerating-cycle apparatus 2 which concerns on Embodiment 1 of this invention. It is a schematic top view which shows the example of the connection structure of the oil equalizing pipe in the refrigerating-cycle apparatus provided with three or more compressors as a modification of Embodiment 1 of this invention.

Embodiment 1 FIG.
A refrigeration cycle apparatus according to Embodiment 1 of the present invention and an air conditioner including the same will be described. FIG. 1 is a refrigerant circuit diagram illustrating a schematic configuration of a refrigeration cycle apparatus 2 according to the present embodiment and an air conditioner 1 including the refrigeration cycle apparatus 2. In FIG. 1, piping through which refrigerant mainly circulates is indicated by a thick line, and piping through which refrigeration oil mainly circulates is indicated by a thin line.

  First, the whole structure of the air conditioner 1 and the refrigerating-cycle apparatus 2 is demonstrated using FIG. As shown in FIG. 1, the air conditioner 1 has a refrigeration cycle apparatus 2. The refrigeration cycle apparatus 2 mainly has a configuration in which the compressors 10 and 30, the four-way valve 40, the outdoor heat exchanger 50, the expansion device 60, and the indoor heat exchanger 70 are sequentially connected in an annular manner through a refrigerant pipe. .

  The air conditioner 1 includes an outdoor unit 100 and an indoor unit 200. The outdoor unit 100 includes the compressors 10 and 30, the four-way valve 40, the outdoor heat exchanger 50 and the expansion device 60, and an outdoor unit fan 51 that blows outside air to the outdoor heat exchanger 50. . The indoor unit 200 includes the indoor heat exchanger 70 and an indoor unit fan 71 that blows indoor air to the indoor heat exchanger 70. In this example, the expansion device 60 is provided in the outdoor unit 100, but the expansion device 60 may be provided in the indoor unit 200. 1 shows only one indoor unit 200, the air conditioner 1 may have a plurality of indoor units 200. Each of the plurality of indoor units 200 includes an indoor heat exchanger 70 connected to the refrigerant circuit in parallel.

  The compressors 10 and 30 are fluid machines that suck in and compress a low-temperature and low-pressure gas refrigerant and discharge it as a high-temperature and high-pressure refrigerant. In the present embodiment, the two compressors 10 and 30 are connected in parallel in the refrigerant circuit. Details of the compressors 10 and 30 will be described later.

  The four-way valve 40 is for switching the refrigerant flow path. In the case of the cooling operation (FIG. 1 shows the case of the cooling operation), the four-way valve 40 allows the high-temperature and high-pressure refrigerant discharged from the compressors 10 and 30 to flow into the outdoor heat exchanger 50 and The refrigerant flow path is switched so that the low-temperature and low-pressure gas refrigerant flowing out of the exchanger 70 is sucked into the compressors 10 and 30. On the other hand, in the case of heating operation, the four-way valve 40 has a low-temperature and low-pressure gas refrigerant discharged from the compressors 10 and 30 flowing into the indoor heat exchanger 70 and flowing out from the outdoor heat exchanger 50. The refrigerant flow path is switched so as to be sucked into the compressors 10 and 30.

  The outdoor unit fan 51 blows outside air to the outdoor heat exchanger 50 by a rotating operation by a motor.

  The outdoor heat exchanger 50 performs heat exchange between the refrigerant flowing through the outdoor heat exchanger 50 and the outside air blown by the outdoor unit fan 51. The outdoor heat exchanger 50 functions as a condenser that condenses the refrigerant in the cooling operation, and functions as an evaporator that evaporates the refrigerant in the heating operation.

  The expansion device 60 expands and decompresses the refrigerant that has flowed in, and causes the refrigerant to flow out as a low-temperature and low-pressure gas-liquid two-phase refrigerant. As the expansion device 60, an expansion valve, a capillary tube, or the like is used.

  The indoor unit fan 71 blows indoor air to the indoor heat exchanger 70 by a rotating operation by a motor.

  The indoor heat exchanger 70 performs heat exchange between the refrigerant flowing through the indoor heat exchanger 70 and indoor air blown by the indoor unit fan 71. The indoor heat exchanger 70 functions as an evaporator that evaporates the refrigerant in the cooling operation, and functions as a condenser that condenses the refrigerant in the heating operation.

  FIG. 2 is a refrigerant circuit diagram showing a refrigerant circuit from the evaporator through the compressors 10 and 30 to the condenser as a main configuration of the refrigeration cycle apparatus 2 according to the present embodiment. In FIG. 2, the compressors 10 and 30 are shown in a longitudinal sectional view, and components other than the compressors 10 and 30 are shown in symbols or blocks. In FIG. 2, the four-way valve 40 is not shown. The “evaporator” in FIG. 2 is the indoor heat exchanger 70 in the cooling operation, and the outdoor heat exchanger 50 in the heating operation. Further, the “condenser” in FIG. 2 is the outdoor heat exchanger 50 in the cooling operation, and the indoor heat exchanger 70 in the heating operation.

  As shown in FIG. 2 and FIG. 1 already shown, the two compressors 10 and 30 are connected in parallel to the refrigerant circuit. In the refrigerant circuit, the suction side pipes downstream from the four-way valve 40 are branched at the branching portion 43 into the same number (two in this example) of suction side branch pipes 41 and 42 as the number of the compressors 10 and 30. The suction side branch pipe 41 is connected to the suction side of the compressor 10, and the suction side branch pipe 42 is connected to the suction side of the compressor 30.

  Further, a discharge side branch pipe 44 is connected to the discharge side of the compressor 10, and a discharge side branch pipe 45 is connected to the discharge side of the compressor 30. The discharge side branch pipes 44 and 45 are provided with check valves 44a and 45a for preventing the refrigerant from flowing backward to the compressors 10 and 30 respectively. The discharge-side branch pipe 44 and the discharge-side branch pipe 45 merge at the junction 46 on the upstream side of the four-way valve 40. An oil separator 47 is provided between the junction 46 and the four-way valve 40. The refrigerating machine oil recovered by the oil separator 47 passes through the oil return pipe 48, is decompressed by the capillary tube 48a, and is separated from the suction side of the compressors 10 and 30 (in this example, downstream of the four-way valve 40, the branch portion 43). To the upstream side).

  The discharge side branch pipe 44 and the suction side branch pipe 41 of the compressor 10 are connected by a bypass pipe 52 for equalizing the discharge side and the suction side when the compressor 10 is activated. The bypass pipe 52 is provided with a valve 52a. The valve 52a is opened immediately before or when the compressor 10 is started under the control of a control device (not shown), and is closed after a predetermined time has elapsed since the start of the compressor 10. Similarly, the discharge side branch pipe 45 and the suction side branch pipe 42 of the compressor 30 are connected by a bypass pipe 53, and the bypass pipe 53 is provided with a valve 53 a. The valve 53a is opened immediately before or when the compressor 30 is started, and is closed after a predetermined time has elapsed since the start of the compressor 30.

  Next, the configuration of the compressor 10 will be briefly described. The compressor 10 of the present embodiment is a two-cylinder rotary compressor that includes two cylinders. The compressor 10 includes a compression mechanism unit 11, an electric motor unit 12 that drives the compression mechanism unit 11, and a sealed container 13 that houses the compression mechanism unit 11 and the electric motor unit 12. The compressor 10 of the present embodiment is a high-pressure container type in which the space in the sealed container 13 is filled with the discharge gas.

  The electric motor unit 12 includes a stator 14 and a rotor 15. The stator 14 is fixed to the sealed container 13. A crankshaft 16 is fitted into the rotor 15. The crankshaft 16 is rotationally driven together with the rotor 15 when electric power is supplied to the stator 14. In this example, an inverter power source that can change the driving rotational speed (frequency) of the crankshaft 16 is used as a power source that supplies power to the stator 14 in order to make the refrigerant circulation amount variable. As a power source for supplying power to the stator 14, a general commercial power source having a frequency of 50 Hz or 60 Hz can also be used. The crankshaft 16 is formed with two upper and lower eccentric parts (upper eccentric part 16a and lower eccentric part 16b) that are eccentric to each other in opposite directions, that is, shifted by 180 degrees in phase.

  The compression mechanism unit 11 is disposed below the electric motor unit 12. The compression mechanism 11 includes an upper cylinder 17, a lower cylinder 18, a partition plate 19 that partitions the upper cylinder 17 and the lower cylinder 18, and upper and lower ends of a stack of the upper cylinder 17, the lower cylinder 18, and the partition plate 19. The main bearing 20 and the sub-bearing 21 also serving as side walls, the upper rolling piston 22 fitted into the upper eccentric portion 16a, the lower rolling piston 23 fitted into the lower eccentric portion 16b, and the inner side of the upper cylinder 17 Has an upper vane (not shown) that partitions the chamber into a compression chamber and a suction chamber, and a lower vane (not shown) that partitions the inside of the lower cylinder 18 into a compression chamber and a suction chamber.

  A connection port 13 a is formed in the side wall of the sealed container 13 so as to open. A connection pipe 24 for connecting an oil equalizing pipe 55 described later is attached to the connection port 13a. That is, the oil equalizing pipe 55 is connected to the connection port 13a via the connection pipe 24. The connection port 13a is provided above the sliding parts of the compression mechanism part 11 (for example, all the sliding parts of the compression mechanism part 11) (in this example, above the upper end surface of the upper cylinder 17). . The connecting tube 24 has a shape that is pulled out horizontally from the hermetic container 13 and then bent upward, and extends upward as it is. In this example, the tip 24 a of the connection pipe 24 is located at a height close to the height of the ceiling portion of the sealed container 13.

  Refrigerating machine oil (lubricating oil) is stored at the bottom of the sealed container 13. In FIG. 2, the oil level OL of the refrigerating machine oil in the compressors 10 and 30 shows a good state in which the oil level is almost above the lower end of the upper cylinder 17 and below the connection port 13a. . If the oil level OL is positioned below the lower end portion of the upper cylinder 17, a shortage of refrigerating machine oil may occur at the sliding portion in the upper cylinder 17.

  On the suction side of the compressor 10, a suction accumulator 25 that separates the sucked low-pressure refrigerant is provided. Only the gas refrigerant in the suction accumulator 25 is sucked into the compressor 10.

  Since the compressor 30 has substantially the same configuration as the compressor 10 described above, the description thereof is omitted. The compressors 10 and 30 of the present example are controlled independently of each other by operating, stopping, and operating frequencies (rotations) by a control device (not shown).

  The tip 24a of the connecting pipe 24 provided in the compressor 10 and the tip 24a of the connecting pipe 24 provided in the compressor 30 are connected by an oil equalizing pipe 55 having an inverted U-shape as a whole. Yes. Thereby, the compressors 10 and 30 are directly connected by the oil equalizing pipe 55. Here, “directly” means that no oil separator, oil tank or the like is interposed therebetween. By connecting the compressors 10 and 30 with the oil equalizing pipe 55, the internal spaces of the compressors 10 and 30 communicate with each other. Therefore, since the refrigerating machine oil can be circulated from one to the other between the compressors 10 and 30 via the oil equalizing pipe 55, the uneven distribution of the refrigerating machine oil can be immediately eliminated. Further, since the internal pressure of the compressors 10 and 30 can be equalized through the oil leveling pipe 55, it is possible to prevent the uneven distribution of refrigerating machine oil due to a minute difference in operating conditions of the compressors 10 and 30. Become.

  The oil equalizing pipe 55 is provided with a valve (open / close valve) 55a. The valve 55a opens and closes the oil equalizing pipe 55 under the control of a control device (not shown). In the present embodiment, when both the compressors 10 and 30 are stopped, or the compressors 10 and 30 are operating at substantially the same frequency (hereinafter simply referred to as “the same frequency”). Sometimes, the valve 55a is opened, and the circulation of the refrigerating machine oil, the refrigerant, etc. in the oil equalizing pipe 55 is allowed. Further, when only one of the compressors 10 and 30 is operating, or when the compressors 10 and 30 are operating at different frequencies, the valve 55a is closed, and the refrigerating machine oil and refrigerant in the oil equalizing pipe 55 are closed. Distribution of such as is blocked. Thus, when only one of the compressors 10 and 30 is operating, or when the compressors 10 and 30 are operating at different frequencies, the valve 55a together with the check valves 44a and 45a , 30 has a function of preventing the compressed refrigerant from flowing into the other. Therefore, in other words, by providing the valve 55a and the check valves 44a and 45a, only one of the compressors 10 and 30 can be operated and the compressors 10 and 30 can be operated at different frequencies. .

  Next, a characteristic operation of the refrigeration cycle apparatus 2 according to the present embodiment will be described. First, the operation when both the compressors 10 and 30 are operating at the same frequency will be described. When the compressors 10 and 30 are operating at the same frequency, the valve 55a provided in the oil equalizing pipe 55 is opened as described above. Thereby, the internal space of the compressor 10 and the internal space of the compressor 30 communicate with each other via the oil equalizing pipe 55. For this reason, when one of the compressors 10 and 30 has an excessive amount of oil and the other has an excessive amount of oil, excess refrigeration oil from one compressor is supplied to the other compressor via the oil equalizing pipe 55. can do. Here, the refrigerating machine oil supplied via the oil equalizing pipe 55 includes not only liquid refrigerating machine oil but also mist refrigerating machine oil. Therefore, the surplus refrigeration oil of one compressor can be supplied to the other compressor only when the oil level of the refrigeration oil in one compressor reaches the position of the connection port 13a. Absent. Thereby, uneven distribution of the refrigeration oil in the compressors 10 and 30 can be eliminated immediately. Further, the internal space of the compressor 10 and the internal space of the compressor 30 communicate with each other via the oil equalizing pipe 55, so that both internal spaces are equalized. For this reason, uneven distribution of refrigerating machine oil due to a minute difference in operating state between the compressors 10 and 30 can be prevented.

  Next, the operation when both the compressors 10 and 30 are stopped will be described. When both the compressors 10 and 30 are stopped, the valve 55a provided in the oil equalizing pipe 55 is opened as described above. Thereby, the internal space of the compressor 10 and the internal space of the compressor 30 communicate with each other via the oil equalizing pipe 55. For this reason, when one of the compressors 10 and 30 has an excessive amount of oil and the other has an excessive amount of oil, the excess refrigeration oil of one compressor is passed through the oil equalizing pipe 55 to the other compressor. Can be supplied.

  Next, when only one of the compressors 10 and 30 is operating (in the case of one-side operation. Hereinafter, a state in which only a part of three or more compressors is operating may also be referred to as one-side operation). Will be described. Here, it is assumed that only the compressor 10 is operating and the compressor 30 is stopped. During the one-side operation, a difference occurs in the pressure in the internal space of the compressors 10 and 30, so that the valve 55a provided in the oil equalizing pipe 55 is closed as described above. Refrigerating machine oil is discharged together with the compressed refrigerant from the operating compressor 10, and a part of the refrigerating machine oil is returned into the compressor 10 through the oil separator 47, the oil return pipe 48 and the suction accumulator 25. On the other hand, the refrigeration oil is not discharged from the compressor 30 that is stopped, and a part of the refrigeration oil discharged from the compressor 10 in operation is part of the oil separator 47, the oil return pipe 48, and the suction. The oil is only returned through the accumulator 25. Since the discharge side branch pipe 45 on the compressor 30 side is provided with the check valve 45a, the backflow of the refrigerant and the refrigerating machine oil from the operating compressor 10 to the stopped compressor 30 is prevented. .

  As a result, during one-side operation, the refrigeration oil gradually decreases in the compressor 10 during operation, and the refrigeration oil gradually increases in the compressor 30 that is stopped. However, when the one-side operation is finished (when both the compressors 10 and 30 are stopped), the valve 55a provided in the oil equalizing pipe 55 is opened as described above. For this reason, when the compressor 30 is excessively oily and the compressor 10 is excessively oily when the one-side operation is finished, the excess of the compressor 30 is stopped while the compressors 10 and 30 are stopped. Refrigerating machine oil can be supplied to the compressor 10 through an oil equalizing pipe 55. Therefore, the required oil level can be ensured in both the compressors 10 and 30 until the compressor 10 or the compressor 30 is started next time. Thereby, since the malfunction by the refrigeration oil shortage at the time of the next starting of the compressors 10 and 30 can be prevented, the reliability at the next starting of the compressors 10 and 30 can be improved, and the compressors 10 and 30 Durability can be improved. As described above, when one of the compressors 10 and 30 has an excessive amount of oil and the other has an excessive amount of oil at the end of one-side operation, a particularly remarkable effect according to the present embodiment can be obtained.

  Next, the operation when the compressors 10 and 30 are operating at different frequencies will be described. Here, it is assumed that the compressor 10 is operating at a relatively high frequency and the compressor 30 is operating at a relatively low frequency. When the compressors 10 and 30 are operating at different frequencies, a difference occurs in the pressures in the internal spaces of the compressors 10 and 30. Therefore, as described above, the valve 55a provided in the oil equalizing pipe 55 is in the closed state. Become. At this time, a phenomenon occurs in which the refrigeration oil of the compressor 10 operating at a high frequency gradually decreases and the refrigeration oil of the compressor 30 operating at a low frequency gradually increases. However, when the operations of the compressors 10 and 30 are completed, the valve 55a provided in the oil equalizing pipe 55 is opened as described above. For this reason, when the compressor 10 and 30 are stopped, when the compressor 30 is excessively oily and the compressor 10 is excessively oily, the compressor 10 and 30 are stopped while the compressor 10 and 30 are stopped. Excess refrigeration oil in the machine 30 can be supplied to the compressor 10 via the oil equalizing pipe 55. Therefore, the required oil level can be ensured in both the compressors 10 and 30 until the compressor 10 or the compressor 30 is started next time. Thereby, since the malfunction by the refrigeration oil shortage at the time of the next starting of the compressors 10 and 30 can be prevented, the reliability at the next starting of the compressors 10 and 30 can be improved, and the compressors 10 and 30 Durability can be improved.

  In addition, as described above, the reliability when performing one-side operation increases, so that it can be used in places where the compressor efficiency is maximized for each operating point depending on the air condition, whether it is total operation or operation with a reduced number of operation. You can choose. That is, even if the refrigeration capacity as a whole is the same, the number of operating units can be made different by changing the frequency of a plurality of compressors. For example, when there are two compressors, only one compressor is operated at 60 rps depending on the air condition, or each of the two compressors is operated at 30 rps. Can be selected. Therefore, it is possible to obtain a refrigeration cycle apparatus and an air conditioner that have a higher energy saving effect than before.

  FIG. 3 is a refrigerant circuit diagram illustrating a main configuration of a refrigeration cycle apparatus that does not include the oil equalizing pipe 55 and the valve 55a as a comparative example of the refrigeration cycle apparatus 2 according to the present embodiment. As shown in FIG. 3, in this refrigeration cycle apparatus, the oil return is between the upstream side of the check side valve 44 a in the discharge side branch pipe 44 and the tip 24 a of the connection pipe 24 provided in the compressor 10. Connected by a tube 56. An oil return pipe 57 connects the upstream side of the discharge side branch pipe 45 with respect to the check valve 45 a and the tip 24 a of the connection pipe 24 provided in the compressor 30. In this configuration, a part of the refrigerating machine oil discharged together with the refrigerant from the compressors 10 and 30 to the discharge side branch pipes 44 and 45 returns to the compressors 10 and 30 through the oil return pipes 56 and 57. Yes.

  In the configuration shown in FIG. 3, for example, in the one-side operation in which only the compressor 30 is operated, the refrigeration oil gradually decreases in the operating compressor 30 and the refrigeration oil gradually increases in the stopped compressor 10. become. At this time, when the compressor 30 has an excessive amount of oil and the compressor 10 has an excessive amount of oil, unlike the present embodiment, even after the one-side operation is finished (after the compressors 10 and 30 are stopped). That state is maintained. Here, FIG. 3 shows a state where the oil level OL of the compressor 30 is at the height of the lower cylinder 18, and the shortage of refrigerating machine oil may occur in the upper cylinder 17. For this reason, when starting the compressor 30 which became oil amount low next, there exists a possibility that the malfunction by lack of refrigerating machine oil may arise.

  Next, the overall cooling operation of the refrigeration cycle apparatus 2 and the air conditioner 1 according to the present embodiment will be briefly described. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressors 10 and 30 flows into the outdoor heat exchanger 50 via the four-way valve 40. The gas refrigerant that has flowed into the outdoor heat exchanger 50 is condensed by heat exchange with the outside air blown by the outdoor unit fan 51, becomes a low-temperature refrigerant, and flows out of the outdoor heat exchanger 50. The refrigerant flowing out of the outdoor heat exchanger 50 is expanded and depressurized by the expansion device 60, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the indoor heat exchanger 70 of the indoor unit 200, evaporates by heat exchange with the indoor air blown by the indoor unit fan 71, and becomes a low-temperature and low-pressure gas refrigerant. It flows out of the exchanger 70. At this time, the indoor air absorbed by the refrigerant and cooled is turned into conditioned air (cold air) and blown out from the outlet of the indoor unit 200 into the room (a space to be conditioned). The gas refrigerant flowing out from the indoor heat exchanger 70 is sucked into the compressors 10 and 30 via the four-way valve 40 and compressed again. The above operation is repeated. In the above operation, not only the refrigerant gas but also the mist refrigerating machine oil circulates in the refrigerant circuit.

  Next, the heating operation operation of the refrigeration cycle apparatus 2 and the air conditioner 1 will be described. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressors 10 and 30 flows into the indoor heat exchanger 70 of the indoor unit 200 via the four-way valve 40. The gas refrigerant that has flowed into the indoor heat exchanger 70 is condensed by heat exchange with room air blown by the indoor unit fan 71, becomes a low-temperature refrigerant, and flows out of the indoor heat exchanger 70. At this time, the indoor air that has been absorbed by the refrigerant and heated is conditioned air (warm air), and is blown into the room from the outlet of the indoor unit 200. The refrigerant flowing out of the indoor heat exchanger 70 is expanded and depressurized by the expansion device 60, and becomes a low-temperature and low-pressure gas-liquid two-phase refrigerant. This gas-liquid two-phase refrigerant flows into the outdoor heat exchanger 50, evaporates by heat exchange with the outside air blown by the outdoor unit fan 51, and flows out of the outdoor heat exchanger 50 as a low-temperature and low-pressure gas refrigerant. To do. The gas refrigerant that has flowed out of the outdoor heat exchanger 50 is sucked into the compressors 10 and 30 via the four-way valve 40 and compressed again. The above operation is repeated. In the above operation, not only the refrigerant gas but also the mist refrigerating machine oil circulates in the refrigerant circuit.

  As described above, in the present embodiment, the compressors 10 and 30 are connected to each other so that the internal spaces of the compressors 10 and 30 are communicated, and the refrigerating machine oil is circulated from one to the other between the compressors 10 and 30. An oil equalizing pipe 55 is provided. According to this configuration, surplus refrigeration oil (liquid state or mist) is connected via the oil equalizing pipe 55 from one of the compressors 10 and 30 having an excessive amount of oil to the other of the compressors 10 and 30 having an excessive amount of oil. State) can be supplied (oil leveling effect). Therefore, the uneven distribution of the retained oil amount in the compressors 10 and 30 can be eliminated immediately. Moreover, according to this structure, each internal space of the compressors 10 and 30 can be equalized via the oil equalization pipe | tube 55 (equalizing effect). Therefore, uneven distribution of refrigerating machine oil due to a minute difference in operating state between the compressors 10 and 30 can be prevented.

  In the present embodiment, a valve 55a for opening and closing the oil equalizing pipe 55 is provided. According to this structure, when the oil level of one compressor falls, it can avoid that the oil level of the other compressor also falls to the lower part. Therefore, the required oil level can be secured in each of the compressors 10 and 30.

  Moreover, in this Embodiment, the connection port 13a connected to the oil equalization pipe | tube 55 is formed in the side wall of the airtight container 13 of the compressors 10 and 30, and the connection port 13a is a compression mechanism part of the compressors 10 and 30. 11 is provided above 11. According to this structure, when the oil level of one compressor falls, it can avoid that the oil level of the other compressor also falls to the lower part. Therefore, it is possible to avoid that the required oil level cannot be secured by both the compressors 10 and 30.

  Further, in the present embodiment, the valve 55a is opened when the compressors 10, 30 are both stopped, or when the compressors 10, 30 are operating at the same frequency, and the compressor 10, 30 When only a part of 30 (one of the compressors 10 and 30 in this example) is operating, or when the compressors 10 and 30 are operating at different frequencies, the closed state is established. According to this configuration, when the operation of the compressors 10 and 30 ends, if the compressor 30 is excessively oily and the compressor 10 is excessively oily, the compressors 10 and 30 are being stopped. In addition, surplus refrigeration oil of the compressor 30 can be supplied to the compressor 10 through the oil equalizing pipe 55. Therefore, since the required oil level can be ensured in both the compressors 10 and 30 before the compressor 10 or the compressor 30 is started next, the reliability at the next start-up of the compressors 10 and 30 is ensured. Can increase the sex.

Other embodiments.
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, a refrigeration cycle apparatus in which two compressors are connected in parallel has been described as an example. However, the present invention is also applicable to a refrigeration cycle apparatus in which three or more compressors are connected in parallel. it can. FIG. 4 is a schematic top view illustrating an example of a connection structure of oil equalizing pipes in a refrigeration cycle apparatus including three or more compressors as a modification of the above embodiment.

  In the example shown to Fig.4 (a), the three compressors 301-303 connected in parallel with the refrigerant circuit are provided. Each of the compressors 301 to 303 has connecting pipes 301a to 303a whose tip is branched into two. One end of the connecting pipe 301a and one end of the connecting pipe 302a are connected via an oil equalizing pipe 311. The other end of the connection pipe 302a and one end of the connection pipe 303a are connected via an oil equalizing pipe 312. The other end of the connecting pipe 303a and the other end of the connecting pipe 301a are connected via an oil equalizing pipe 313. Valves 311a to 313a are provided in the oil equalizing tubes 311 to 313, respectively. That is, in the example shown in FIG. 4A, each of the three compressors 301 to 303 is connected to the other two compressors via oil leveling tubes 311 to 313 provided with valves 311a to 313a. Connected in a one-to-one relationship.

  An example of the open / close state of the valves 311a to 313a in the example shown in FIG. When all of the compressors 301 to 303 are operating at the same frequency, or when all of the compressors 301 to 303 are stopped, all the valves 311a to 313a are opened. When the compressors 301 and 302 are operating at the same frequency and the compressor 303 is stopped (or when only the compressor 303 is operating at a different frequency), a valve 311a between the compressors 301 and 302 is used. Only the valve 312a and 313a are closed. When only the compressor 301 is operating and the compressors 302 and 303 are stopped, all the valves 311a to 313a are closed. When the compressors 301 and 302 operate at different frequencies and the compressor 303 is stopped, or when all of the compressors 301 to 303 operate at different frequencies, all the valves 311a to 313a are closed. It becomes. According to the configuration shown in FIG. 4A, the same effects as in the above embodiment can be obtained by operating the valves 311a to 313a as described above.

  In the example shown in FIG. 4B, four compressors 301 to 304 connected in parallel to the refrigerant circuit are provided. The oil equalizing pipe 320 used in this example has a central portion 325 and radial portions 321 to 324 having a number equal to the number of the compressors 301 to 304 that are radially branched from the central portion 325. The distal ends of the radial parts 321 to 324 are connected to the compressors 301 to 304 (connection pipes). Valves 321a to 324a are provided in the radial portions 321 to 324, respectively. That is, in the example shown in FIG. 4B, each of the compressors 301 to 304 is connected to the center portion 325 via radial portions 321 to 324 provided with valves 321a to 324a.

  An example of the open / closed state of the valves 321a to 324a in the example shown in FIG. 4B will be described. When all of the four compressors 301 to 304 are operating at the same frequency, or when all of the four compressors 301 to 304 are stopped, all the valves 321a to 324a are opened. . When three compressors 301, 302, and 303 are operating at the same frequency and one compressor 304 is stopped (or when only one compressor 304 is operating at a different frequency) The valves 321a to 323a are opened, and only the valve 324a is closed. When only one compressor 301 is operating and the three compressors 302, 303, 304 are stopped, all the valves 321a to 324a are closed. When two compressors 301 and 302 operate at the same frequency, one compressor 303 operates at a different frequency, and one compressor 304 is stopped, the valves 321a and 322a are opened. The valves 323a and 324a are closed. When the two compressors 301 and 302 operate at the same frequency and the two compressors 303 and 304 operate at the same frequency different from the compressors 301 and 302, the valves 321a and 322a are in the open state. Then, the valves 323a and 324a are closed, or the valves 321a and 322a are closed and the valves 323a and 324a are opened.

  According to the configuration shown in FIG. 4B, the same effect as in the above embodiment can be obtained by operating the valves 321a to 324a as described above. Also, compared with the configuration shown in FIG. 4A, in the configuration shown in FIG. 4B, the number of valves 321a to 324a when the number of compressors 301 to 304 is large (when 4 or more) is used. Can be reduced.

  In the example shown in FIG. 4C, four compressors 301 to 304 connected in parallel to the refrigerant circuit are provided. The oil equalizing pipe 330 used in this example includes an annular portion 335 provided in an annular shape at the center, and radial portions 331 to 334 having a number equal to the number of the compressors 301 to 304 that are radially branched from the annular portion 335, respectively. have. The distal ends of the radial parts 331 to 334 are connected to the compressors 301 to 304 (connection pipes). Each of the radial parts 331 to 334 is provided with valves 331a to 334a. That is, in the example shown in FIG. 4C, each of the compressors 301 to 304 is connected to the annular portion 335 via radial portions 331 to 334 provided with valves 331a to 334a.

  According to the configuration shown in FIG. 4C, the same effects as in the above embodiment can be obtained by operating the valves 331a to 334a in the same manner as the valves 321a to 324a shown in FIG. Further, in the configuration shown in FIG. 4C, the branch structure of the oil equalizing pipe 330 when the number of the compressors 301 to 304 is large can be simplified as compared with the configuration shown in FIG.

  In the above embodiment, a two-cylinder rotary compressor is taken as an example. However, the present invention can also be applied to a rotary compressor including one or three or more cylinders. The present invention can also be applied to a compressor other than the rotary compressor.

  Further, the above embodiments and modifications can be implemented in combination with each other.

  DESCRIPTION OF SYMBOLS 1 Air conditioner, 2 Refrigeration cycle apparatus 10, 30, 301, 302, 303, 304 Compressor, 11 Compression mechanism part, 12 Electric motor part, 13 Airtight container, 13a Connection port, 14 Stator, 15 Rotor, 16 Crankshaft, 16a Upper eccentric part, 16b Lower eccentric part, 17 Upper cylinder, 18 Lower cylinder, 19 Partition plate, 20 Main bearing, 21 Sub bearing, 22 Upper rolling piston, 23 Lower rolling piston, 24, 301a, 302a, 303a Connection pipe, 24a tip, 25 Suction accumulator, 40 Four-way valve, 41, 42 Suction side branch pipe, 43 Branch part, 44, 45 Discharge side branch pipe, 44a, 45a Check valve, 46 Junction part, 47 Oil separator, 48 oil return pipe, 48a capillary tube, 50 outdoor heat exchanger, 51 outdoor unit fan, 52, 3 Bypass piping, 52a, 53a valve, 55, 311, 312, 313, 320, 330 Oil equalizing pipe, 55a, 311a, 312a, 313a, 321a, 322a, 323a, 324a, 331a, 332a, 333a, 334a Valve, 56, 57 oil return pipe, 60 expansion device, 70 indoor heat exchanger, 71 fan for indoor unit, 100 outdoor unit, 200 indoor unit, 321, 322, 323, 324, 331, 332, 333, 334 radial part, 325 center part 335 Annulus, OL Oil level.

Claims (4)

A refrigeration cycle apparatus including a plurality of compressors connected in parallel,
An oil equalizing pipe that connects the compressors to communicate the internal space of the compressors and distributes refrigeration oil between the compressors;
A valve for opening and closing the oil equalizing pipe;
A refrigeration cycle apparatus comprising: A connection port connected to the oil equalizing pipe is formed on the side wall of the compressor,
The refrigeration cycle apparatus according to claim 1, wherein the connection port is provided above a compression mechanism portion of the compressor. The valves are open when all of the compressors are stopped or when the compressors are operating at the same frequency,
The refrigeration cycle apparatus according to claim 1 or 2, wherein only a part of the compressor is operating, or the compressor is operating at a frequency different from each other. . An air conditioner comprising the refrigeration cycle apparatus according to any one of claims 1 to 3.

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