JP6242235B2 - Heat source unit and refrigeration cycle apparatus - Google Patents

Description

  The present invention relates to a heat source unit and the like. In particular, the present invention relates to the distribution of the amount of refrigeration oil among a plurality of parallel-connected compressors of the heat source unit.

  For example, there is a refrigeration cycle apparatus in which a refrigerant circuit is configured by connecting a plurality of compressors in parallel in order to compensate for a lack of capacity in one compressor. Here, when a plurality of compressors are connected by piping to circulate the refrigerant, the amount of refrigeration oil in each compressor often becomes non-uniform. If the amount of the refrigerating machine oil becomes uneven, the refrigerating machine oil of a specific compressor becomes excessive, while the refrigerating machine oil of another compressor becomes insufficient. In a compressor in which refrigeration oil is insufficient, the compression mechanism inside the compressor is insufficiently lubricated. For this reason, the sliding part of a compression mechanism raise | generates a metal contact, and a compressor may break down.

  Therefore, various measures have been proposed so that the refrigerating machine oil between the compressors does not become non-uniform. For example, there is an oil leveling device in which an oil leveling pipe provided in a sealed container of a hermetic compressor is connected to a low-pressure side gas-liquid separator and then decompressed by a capillary tube to return refrigeration oil to the compressor (for example, Patent Document 1).

  Also, without connecting the oil equalizing pipe to the hermetic compressor, the refrigerating machine oil discharged from the hermetic compressor to the high-pressure side pipe is retained in the oil separator provided on the high-pressure side, and the oil separator and the low-pressure side pipe There is a refrigerating apparatus or the like that returns a refrigerating machine oil to a compressor by connecting a pipe having a pressure reducing mechanism such as a capillary between them (for example, see Patent Documents 2 and 3). In these apparatuses, since a check valve is not provided in the high-pressure side pipe near the compressor, when applied to a rolling piston (rotary) type compressor, a pressure difference remains in the compressor and the refrigeration oil flows backward. The phenomenon was happening.

JP 2007-139215 A (page 10, FIG. 1) Japanese Patent Laying-Open No. 2006-220342 (page 12, FIG. 1) JP 2006-064267 A (6th page, FIG. 1)

  Here, for example, when a plurality of compressors are driven at different driving frequencies, the amount of refrigerating machine oil taken out of the compressor together with the refrigerant increases in a compressor driven at a high driving frequency. On the other hand, in a compressor driven at a low drive frequency, the amount of refrigeration oil taken out of the compressor is small. For this reason, in order to make the amount of refrigerating machine oil uniform among a plurality of compressors, return a large amount of refrigerating machine oil to a compressor with a large amount of refrigerating machine oil being taken out, and compression with a small amount of refrigerating machine oil taken out. It is necessary to return a small amount of refrigeration oil to the machine. Moreover, the drive frequency of the compressor is changing every moment. Therefore, when a non-uniform amount of refrigeration oil occurs between a plurality of compressors, it is necessary to quickly eliminate the non-uniformity.

  In order to eliminate the non-uniformity, the refrigerating machine oil discharged from the hermetic compressor to the high-pressure side piping is retained in the oil separator provided on the anti-compressor side from the high-pressure side confluence, and a pressure reducing mechanism such as a capillary tube Is provided in the middle of the oil return pipe connected to the low pressure side pipe from the oil separator. At this time, if the oil return pipe is connected to the compressor side from the low-pressure side branch point, the refrigerating machine oil is distributed in an equal amount regardless of the flow rate difference between the plurality of compressors. For example, when a plurality of compressors are driven at different operating frequencies, the amount of refrigerating machine oil taken out of the compressor can be sufficiently returned to a compressor that is driven at a high frequency. It was not possible to resolve the unevenness in the amount of refrigeration oil between the compressors.

  As a solution, there is a method of connecting an oil return pipe from the low-pressure side branch point to the anti-compressor side (upstream side in the refrigerant flow). With this method, the refrigeration oil can be distributed according to the flow rates of the plurality of compressors at the low-pressure branch point. Even when multiple compressors are driven at different operating frequencies, a large amount of refrigeration oil is taken out of the compressor, and a large amount of refrigeration oil can be returned to a compressor driven at a high driving frequency. As a result, it was helpful in eliminating non-uniformity in the amount of refrigerating machine oil between multiple compressors.

  However, the effect of eliminating the non-uniformity in the amount of refrigeration oil between the compressors depends on the amount of refrigeration oil discharged from the compressor. In particular, when a large amount of refrigerating machine oil stays in a specific compressor, it takes time for the refrigerating machine oil to be sufficiently discharged outside the compressor, eliminating the unevenness in the amount of refrigerating machine oil between the compressors. It took time to do so.

  Furthermore, as a solution, the oil equalizing pipe provided in the outer casing of the hermetic compressor is connected to the low-pressure side gas-liquid separator, and after being decompressed by the capillary, connected to the low-pressure side pipe and the refrigerating machine oil is returned to the compressor. A technique for shortening the time until the non-uniformity in the amount of refrigerating machine oil between the compressors has been proposed by adopting a form, but it is necessary to newly install a gas-liquid separator and a capillary tube. In addition, by providing a capillary tube, pressure loss increases and the outflow amount of the refrigerating machine oil is limited, so that the time until the non-uniformity of the refrigerating machine oil amount between the compressors can be sufficiently shortened. Did not come.

  Further, for example, when a certain compressor is stopped, refrigerant flows in from another compressor, and a pressure difference is generated inside the stopped compressor. For this reason, particularly when a high-pressure shell type rotary compressor in which the inside of the sealing device has a high pressure is used, the refrigerating machine oil flows out to the compressor having a low pressure through the oil supply hole inside the compression mechanism.

  This invention was made in order to solve the above problems, and it aims at obtaining the heat source unit etc. which can return refrigerator oil by more appropriate distribution with respect to each compressor connected in parallel. To do.

The heat source unit according to the present invention is a heat source unit having a plurality of compressors connected in parallel, and is a discharge pipe that is a pipe between a discharge side of the compressor and a junction where refrigerant discharged from each compressor joins. Side branch pipes and compressor side walls are provided between a plurality of oil leveling pipes that connect the pipes and between the junctions of the oil leveling pipes and the discharge side branch pipes at the junctions. Between the plurality of check valves and the condenser that condenses the refrigerant by heat exchange with the compressor, and has an oil separator that separates the oil discharged from the compressor and a capillary tube, and branches to each compressor An oil return pipe connecting the upstream side refrigerant pipe and the oil separator in the refrigerant flow from the refrigerant branch point, and the oil return pipe is inserted into the refrigerant pipe at the connection with the refrigerant pipe. The inserted tip is occluded and inserted The side surface of the pipe has one or a plurality of small holes, and the small holes have a diameter not less than 0.5 times and not more than 2.0 times the wall thickness of the oil return pipe, and face the refrigerant flow direction in the refrigerant pipe. It is formed within a range of ± 80 ° with respect to the direction to be performed .

  According to the present invention, the refrigerating machine oil can be prevented from being insufficient in each compressor by returning the refrigerating machine oil to each of the compressors connected in parallel with an appropriate distribution. It can prevent that a moving part raise | generates a metal contact and a compressor fails.

It is a figure which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. In the air conditioning apparatus 1 which concerns on Embodiment 1 of this invention, it is a figure which shows the structure in the refrigerant circuit from an evaporator through the compressor 10 to a condenser. It is a figure explaining the detail of the connection part of the oil return pipe | tube 48 and refrigerant | coolant piping which concerns on Embodiment 1 of this invention.

  Hereinafter, a refrigeration cycle apparatus and the like according to embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals denote the same or corresponding parts, and are common to all the embodiments described below. And the form of the component represented by the whole specification is an illustration to the last, Comprising: It does not limit to the form described in the specification. In addition, when there is no need to particularly distinguish or identify a plurality of similar devices that are distinguished by subscripts, the subscripts may be omitted. In the drawings, the relationship between the sizes of the constituent members may be different from the actual one.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. FIG. 1 illustrates an air conditioner 1 as an example of a refrigeration cycle apparatus having a heat source unit. In FIG. 1, piping through which refrigerant mainly flows is shown by a thick line, and piping through which refrigeration oil flows mainly is shown by a thin line.

  As shown in FIG. 1, the air conditioner 1 is mainly composed of two compressors 10a and 10b, a four-way valve 40, an outdoor heat exchanger 50, an expansion device 60, and an indoor heat exchanger 70 that are sequentially annulared by refrigerant piping. To form a refrigerant circuit.

  Moreover, the air conditioning apparatus 1 has the outdoor unit 100 used as a heat source unit, and the indoor unit 200 used as a load side unit. The outdoor unit 100 includes the compressor 10a, the compressor 10b, the four-way valve 40, the outdoor heat exchanger 50, the expansion device 60, and the accumulator 80. Further, the outdoor heat exchanger 50 has an outdoor unit fan 51 for blowing outside air. On the other hand, the indoor unit 200 includes the indoor heat exchanger 70 described above. Moreover, it has the indoor unit fan 71 which blows indoor air (air of air-conditioning object space) to the indoor heat exchanger 70. Here, in the present embodiment, the outdoor unit 100 includes the expansion device 60, but the expansion device 60 may be included in the indoor unit 200. 1 shows only one indoor unit 200, the air-conditioning apparatus 1 may have a plurality of indoor units 200. When a plurality of indoor units 200 are provided, the indoor heat exchangers 70 included in each indoor unit 200 are connected in parallel to each other in the refrigerant circuit.

  The compressor 10 (the compressor 10a and the compressor 10b) is a fluid machine that sucks and compresses a low-temperature and low-pressure gas refrigerant and discharges it as a high-temperature and high-pressure refrigerant. In the present embodiment, two compressors 10a and 10b are connected in parallel in the refrigerant circuit. Details of the compressor 10 will be described later.

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

  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, for example, an expansion valve, a capillary tube (capillary tube) or the like is used. The accumulator 80 separates the gas refrigerant and the liquid refrigerant and accumulates excess refrigerant.

  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 diagram showing a configuration in a refrigerant circuit from the evaporator through the compressor 10 (compressor 10a, compressor 10b) to the condenser in the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. In FIG. 2, the compressor 10 is shown in a longitudinal sectional view for explaining the internal configuration, and components other than the compressor 10 a and the compressor 10 b are shown in symbols or blocks. Here, the illustration of the four-way valve 40 is omitted in FIG. 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 10a and 10b are connected in parallel to the refrigerant circuit. The refrigerant pipe connecting the evaporator (four-way valve 40) and the suction side of the compressor 10 in the refrigerant circuit is at the low-pressure side branch point 43 on the downstream side (compressor 10 side) of the compressor 10. The suction side branch pipe 41 (suction side branch pipe 41a, suction side branch pipe 41b) branches to the same number (two in this embodiment). Each suction side branch pipe 41 is connected to the suction side of the compressor 10.

  The refrigerant pipe connecting the condenser (four-way valve 40) and the discharge side of each compressor 10 is a discharge side branch pipe 44 (discharge side branch pipe 44a, discharge side branch pipe) corresponding to each compressor 10. 44b). Each of the discharge side branch pipes 44 includes a check valve 45 (a check valve 45a and a check valve 45b that prevents the refrigerant from flowing back to the discharge side of the other compressor 10 when, for example, the driving frequency is different. ) Is provided. Each discharge-side branch pipe 44 joins at a high-pressure side junction 46 on the upstream side (compressor 10 side) of the four-way valve 40.

  An oil separator 47 for separating the refrigerant and the refrigerating machine oil is provided between the high pressure side junction 46 and the four-way valve 40 (on the side of the anti-compressor 10 with respect to the high pressure side junction 46). The refrigerating machine oil separated and recovered by the oil separator 47 passes through the oil return pipe 48 and is decompressed by a capillary tube (capillary tube) 49. Then, the refrigerant flows into the refrigerant pipe on the suction side of the compressor 10 and is returned to the compressor 10. Here, in the present embodiment, the oil return pipe 48 is connected to the refrigerant pipe on the downstream side of the four-way valve 40 and on the upstream side of the low-pressure side branch point 43 (on the side of the anti-compressor 10).

  FIG. 3 is a diagram illustrating details of a connection portion between the oil return pipe 48 and the refrigerant pipe according to Embodiment 1 of the present invention. The connecting portion has a shape in which an oil return pipe 48 having a smaller diameter than the refrigerant pipe is inserted into the refrigerant pipe. The tip of the return oil pipe 48 is closed, and the inside of the return oil pipe 48 and the inside of the refrigerant pipe are communicated with a portion facing the inside of the refrigerant pipe in a direction opposite to the flow of the refrigerant in the refrigerant pipe. One or a plurality of small holes 48a through which the refrigerant flows into the refrigerant pipe are provided. The small hole 48 a has a diameter 0.5 to 2.0 times the wall thickness of the oil return pipe 48. Further, when the direction facing the direction in which the refrigerant flows in the refrigerant pipe is 0 °, the refrigerant pipe is provided within a range of ± 80 °.

  When the return oil pipe 48 and the refrigerant pipe are simply connected, oil droplets of the refrigerating machine oil that has flowed out of the return oil pipe 48 adhere to the wall surface of the refrigerant pipe, resulting in a non-uniform concentration with respect to the refrigerant in the refrigerant pipe. May end up. If the concentration with respect to the refrigerant flowing through the refrigerant pipe is not uniform, the amount of refrigerating machine oil flowing into the compressor 10 does not correlate with the refrigerant flow rate. For this reason, it may not be possible to cause each compressor 10 to flow in the amount of refrigeration oil corresponding to the flow rate of the refrigerant.

  Here, in Patent Document 3 described above, the flow of the refrigerating machine oil from the oil return pipe and the flow of the refrigerant in the refrigerant pipe are opposed to the portion flowing into the refrigerant pipe from the oil return pipe to obstruct the flow direction of the refrigerating machine oil from the oil return pipe. A branch joint provided with a plate was provided. And the proposal which makes the density | concentration with respect to a refrigerant | coolant uniform is made by making it mist-like by making a refrigerating machine oil collide with a baffle plate, and making it easy to stir by a refrigerant | coolant. However, this method requires a new branch joint, leading to deterioration in workability and an increase in material costs.

  Therefore, in the present embodiment, a new branch joint is not required, and the refrigerating machine oil flowing out from the oil return pipe 48 can be fogged only by processing the tip of the oil return pipe 48 connected to the refrigerant pipe on the refrigerating machine oil return side. By making it easy to be stirred by the refrigerant flowing in the refrigerant pipe, the concentration of the refrigerating machine oil with respect to the refrigerant can be made uniform.

  Therefore, the refrigerating machine oil is distributed to each intake side branch pipe 41 at the low pressure side branch point 43. Since the amount of refrigerant sucked by the compressor 10 is proportional to the driving frequency, the amount of refrigerating machine oil flowing together with the refrigerant is also distributed according to the driving frequency. Therefore, an appropriate amount of refrigerating machine oil can be distributed to each compressor 10 in accordance with the flow rate of the refrigerant, and the effect of equalizing the oil level in the compressor 10 can be enhanced.

  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, a motor unit 12 that drives the compression mechanism unit 11, and a sealed container 13 that houses the compression mechanism unit 11 and the motor unit 12. The compressor 10 of the present embodiment is a high-pressure container (high-pressure shell) type compressor in which the space in the sealed container 13 is filled with the discharge gas (high-pressure refrigerant atmosphere) after the compression stroke. Here, in the rotary compressor, the positions of the compression mechanism unit 11 and the space where the refrigerating machine oil is stored are close.

  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 the present embodiment, an inverter power source (DC inverter) that can change the rotation speed (drive frequency) of the crankshaft 16 is used as a power source for supplying power to the stator 14 in order to make the refrigerant circulation amount variable. . Here, 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 may be used. The crankshaft 16 is formed with two upper and lower eccentric portions (upper eccentric portion 16a and lower eccentric portion 16b) that are eccentric in opposite directions (with a phase shift of 180 degrees).

  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 connecting pipe 24 for connecting an oil equalizing pipe 55 (55a, 55b) to be described later is attached to the connection port 13a. 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. FIG. 2 shows a good state in which the oil level OL of the refrigeration oil in the compressor 10 is generally 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.

  A suction accumulator that separates the sucked low-pressure refrigerant into a gas and liquid is provided on the suction side of the compressor 10. Only the gas refrigerant in the suction accumulator is sucked into the compressor 10. An oil leveling pipe 55 connects the upstream side (compressor side) of the discharge side branch pipe 44 with respect to the check valve 45 and the connection pipe 24 of the compressor 10.

  In the compressor 10a and the compressor 10b of the present embodiment, the driving frequency (rotation speed) during operation, stop, and operation is controlled independently by a control device (not shown).

  Here, FIG. 2 shows a state in which the oil level OL of the compressor 10b is at the height of the lower cylinder 18 and the upper cylinder 17 may be short of refrigerating machine oil. For this reason, when starting the compressor 10b which became oil amount low next, there exists a possibility that the malfunction by lack of refrigerating machine oil may arise.

  Here, operation | movement of the air conditioning apparatus 1 at the time of the air_conditionaing | cooling operation which concerns on this Embodiment is demonstrated based on the flow of a refrigerant | coolant. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 10 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 compressor 10 via the four-way valve 40 and compressed again. The above operation is repeated. In the above operation, the refrigerant discharged from the compressor 10 includes refrigeration oil.

  Furthermore, operation | movement of the air conditioning apparatus 1 at the time of the heating operation which concerns on this Embodiment is demonstrated based on the flow of a refrigerant | coolant. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 10 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 compressor 10 via the four-way valve 40 and compressed again. The above operation is repeated. Also in the above operation, the refrigerant discharged from the compressor 10 includes refrigeration oil.

  Here, for example, as shown in FIG. 2, the oil level OL in the compressor 10 is determined by pressure and temperature conditions, the amount of refrigeration oil flowing into the compressor 10, and the amount of refrigeration oil flowing out from the compressor 10. When a plurality of compressors 10 are connected in parallel in the refrigerant circuit, the pressure and temperature conditions are basically the same for each compressor 10. For this reason, the oil level is naturally the same. However, since it takes time until the oil level becomes the same naturally, the amount of refrigeration oil flowing into the compressor 10 and the amount of refrigeration oil flowing out of the compressor 10 are controlled in order to achieve uniformization as soon as possible. There is a need to.

  Therefore, in the present embodiment, the amount of refrigerating machine oil flowing out from the compressor 10 is controlled by causing the refrigerating machine oil in the compressor 10 to flow out through the oil equalizing pipe 55. Further, by distributing an appropriate amount of refrigeration oil through the oil return pipe 48, the amount of refrigeration oil flowing into the compressor 10 is controlled.

  Next, the flow of refrigeration oil in the compressor 10 will be described. Refrigerating machine oil is stored in the lower part inside the compressor 10. When the compressor 10 is driven, a centrifugal force due to the rotation of the crankshaft 16 acts to generate a negative pressure, and the refrigerating machine oil is sucked into the holes of the crankshaft 16. The refrigerating machine oil sucked into the radial hole formed in the eccentric part is supplied to the surface of the rolling piston or the like and flows out together with the compressed refrigerant. Further, the refrigerating machine oil sucked into the radial holes formed at the main shaft root and the sub shaft root is supplied between the shaft and the bearing, and flows out through the clearance above the shaft and the bearing. The refrigeration oil that has flowed out becomes oil droplets and scatters in the space below the motor in the compressor 10. Part of the scattered refrigeration oil passes through a hole made in the motor and flows out of the compressor 10 together with the discharge of the refrigerant. Further, the connecting pipe 24 communicates with the space below the motor. For this reason, in the present embodiment, the refrigeration oil scattered in the space below the motor flows out to the outside of the compressor 10 (refrigerant circuit) via the oil equalizing pipe 55 connected to the connection pipe 24.

  For this reason, in the present embodiment, not only the refrigerating machine oil flows out together with the discharge of the refrigerant, but also flows out of the compressor 10 through the oil equalizing pipe 55. Therefore, the amount of outflow increases even if the compressor oil in the compressor 10 is excessive. Then, by distributing an appropriate amount of the refrigerating machine oil to each compressor 10 via the oil return pipe 48, the time for eliminating the unevenness of the refrigerating machine oil amount between the compressors 10 is shortened.

  As described above, according to the air conditioner 1 of the present embodiment, the refrigerant piping on the downstream side of the oil separator 47 and the four-way valve 40 and upstream of the low-pressure branch point 43 (on the side of the anti-compressor 10). And the oil return pipe 48 having the capillary tube 49 is provided, so that the refrigerating machine oil related to the separation and recovery of the oil separator 47 is in an amount based on the driving frequency of each compressor 10 at the low pressure side branch point 43, It is possible to branch to the corresponding suction side branch pipe 41. For this reason, for example, when a plurality of compressors 10 are driven at different driving frequencies, a large amount of refrigerating machine oil can be returned to the compressor 10 having a large amount of refrigerating machine oil taken out of the compressor 10. Therefore, it is possible to solve the problem that the amount of refrigeration oil between the compressors 10 is not uniform.

  Moreover, pressure loss is provided by providing the oil equalizing pipe 55 which does not have pressure reduction mechanisms, such as a capillary tube, which connects the connection port 13a on the side wall of the sealed container 13 and the refrigerant pipe closer to the compressor 10 than the high-pressure side junction 46. It is possible to prevent the non-uniformity in the amount of refrigerating machine oil between the compressors 10 and to shorten the time required to secure a sufficient amount of refrigerating machine oil flow.

  Further, a check valve 45 is provided between the high-pressure side junction 46 and the connecting portion between the oil leveling pipe 55 and the refrigerant pipe so as to prevent the reverse flow of the refrigerating machine oil flowing together with the refrigerant and refrigerant by the other compressor 10. Therefore, it is possible to prevent the refrigerating machine oil from being biased and stored in the compressor 10 that is stopped. The effect is particularly great when a rotary compressor in which the compression mechanism unit 11 and the refrigerating machine oil storage part are close to each other is used.

  As described above, in the outdoor unit (heat source unit) 100 of the air conditioner 1 that circulates the refrigerant by connecting a plurality of the compressors 10 in parallel, it is possible to prevent an insufficient amount of refrigeration oil in each compressor 10 and insufficient lubrication. Therefore, it is possible to prevent failure due to metal contact in the sliding portion of the compression mechanism.

Embodiment 2. FIG.
Although the two-cylinder rotary compressor has been described as an example in Embodiment 1, the present invention can also be applied to a rotary compressor including one or three or more cylinders.

  Moreover, in the above-mentioned embodiment, although the air conditioning apparatus 1 was demonstrated as an example of a refrigerating cycle apparatus, it is not limited to this. For example, the present invention can be applied to other refrigeration cycle apparatuses such as a refrigeration apparatus and a refrigeration apparatus.

  DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 10,10a, 10b 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 eccentricity 17 Upper cylinder, 18 Lower cylinder, 19 Partition plate, 20 Main bearing, 21 Sub bearing, 22 Upper rolling piston, 23 Lower rolling piston, 24 Connection pipe, 24a Tip, 40 Four-way valve, 41, 41a, 41b Suction side Branch piping, 43 Low pressure side branch point, 44, 44a, 44b Discharge side branch piping, 45, 45a, 45b Check valve, 46 High pressure side junction, 47 Oil separator, 48 Oil return pipe, 48a small hole, 49 Capillary tube, 50 outdoor heat exchanger, 51 outdoor unit fan, 55, 55a, 55b oil equalizing pipe, 60 expansion device, 70 indoor heat exchanger, 71 Indoor unit fan, 80 accumulator, 100 outdoor unit, 200 indoor unit.

Claims (5)

A heat source unit having a plurality of compressors connected in parallel,
A plurality of oil equalizing pipes each connecting a discharge side branch pipe that is a pipe between a discharge side of the compressor and a junction where refrigerant discharged from each compressor joins, and a side wall of the compressor;
In each discharge side branch pipe, a plurality of check valves respectively provided between the connecting portion of the oil equalizing pipe and the discharge side branch pipe, and the junction point ;
An oil separator that is between the compressor and a condenser that condenses the refrigerant by heat exchange and separates oil discharged from the compressor;
An oil return pipe that pipe-connects the upstream refrigerant pipe and the oil separator in the refrigerant flow with respect to the refrigerant branch point that has a capillary tube and branches to each compressor;
The oil return pipe is inserted to the inside of the refrigerant pipe at the connection portion with the refrigerant pipe, the inserted tip is closed, and the inserted pipe side surface has one or a plurality of small holes,
The small hole has a diameter not less than 0.5 times and not more than 2.0 times the wall thickness of the oil return pipe, and is formed within a range of ± 80 ° with respect to a direction facing the refrigerant flow direction in the refrigerant pipe. a heat source unit, characterized in that that. 2. The heat source unit according to claim 1 , wherein the plurality of compressors are variable speed compressors whose rotation speed can be independently changed. The heat source unit according to claim 1 or 2 , wherein the compressor has a refrigerant atmosphere in a sealed container having a pressure after a compression stroke. The compressor, the heat source unit according to any one of claims 1 to 3, characterized in that a rotary compressor. The heat source unit according to any one of claims 1 to 4 ,
A refrigeration cycle apparatus comprising a refrigerant circuit by pipe-connecting at least a load side unit having a load heat exchanger.

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