JP4027932B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner including a plurality of compressors.

In the air conditioner, an oil separator is provided in the discharge pipe of the compressor in order to collect oil (lubricating oil) mixed in the gas refrigerant discharged from the compressor. Furthermore, some air conditioners are configured to collect oil that circulates with a gas refrigerant in an accumulator without being separated by an oil separator. Here, when the air conditioner is equipped with a plurality of compressors, U-shaped inflow pipes are provided in the accumulator by the number of compressors, and oil return for sucking oil into the bottoms of the inflow pipes is provided. Make a hole. Then, a suction pipe connected to the discharge side of the compressor is connected to each inflow pipe (for example, see Patent Document 1). By comprising in this way, the oil discharged from the compressor is returned to each compressor via an accumulator.
Japanese Patent Laid-Open No. 3-134447

However, in this type of air conditioner, the amount of oil returned to each compressor varies depending on the pipe diameter of the suction pipe, the amount of refrigerant circulation, the diameter of the oil return hole, and the amount of liquid in the accumulator. Then, it became difficult to return an appropriate amount of oil to each compressor, and the oil level of each compressor was easily biased.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide the oil that is sucked into a plurality of compressors by flowing the oil in a liquid film state in the pipe. This is to prevent the return amount from being biased.

The invention according to claim 1 of the present invention that solves the above-mentioned problems is a plurality of compressors arranged in parallel, a discharge pipe connected to the discharge side of the compressor, and discharged to the discharge pipe Heat exchanger of outdoor unit to which refrigerant is supplied, heat exchanger of indoor unit, main suction pipe into which refrigerant flowing through the heat exchanger flows, branch from the main suction pipe and the compressor A branch intake pipe connected to each of the oil supply section, an oil storage section projecting so as to store liquid oil in the main suction pipe, and the oil storage section using a fluid diverted from the discharge pipe as a driving flow The air conditioner is characterized by having a two-fluid nozzle that sucks the oil accumulated in the nozzle and blows it out to the main suction pipe.
In this air conditioner, when the oil circulating in the circuit together with the refrigerant is liquefied to form a liquid film on the wall surface of the pipe, the liquid film is temporarily stored in the oil reservoir and the two-fluid nozzle It is sucked by the driving flow, becomes a mist state, is jetted to the main suction pipe, is appropriately distributed to each branch suction pipe, and is sucked into each compressor.

The invention according to claim 2 is the air conditioner according to claim 1, wherein the two-fluid nozzle is provided between the oil reservoir and a branch point of the branch suction pipe. To do.
In this air conditioner, the oil sucked from the oil reservoir by the two-fluid nozzle and spouted is quickly distributed to the suction branch pipe and sucked into each compressor.

The invention according to claim 3 is the air conditioner according to claim 2, wherein the two-fluid nozzle is provided immediately before a branch point of the branch intake pipe.
In this air conditioner, the oil sucked and ejected from the oil reservoir is mixed with the refrigerant and then immediately distributed through the branch points to the respective branch intake pipes. As a result, an oil liquid film does not adhere to the pipe wall of the main suction pipe, and the oil is distributed to the branch suction pipes through the branch points and sucked into the respective compressors.

The invention according to claim 4 is the air conditioner according to any one of claims 1 to 3, wherein an oil separator is provided in the discharge pipe, and the oil is separated from the gas refrigerant by the oil separator. An oil return pipe through which the oil flows is connected to the two-fluid nozzle, and oil flowing through the oil return pipe is used as a driving flow.
In this air conditioner, when the oil separated from the gas refrigerant by the oil separator is recovered by the compressor, the liquid oil in the oil reservoir is sucked by using the high-pressure oil as a driving flow.

According to a fifth aspect of the present invention, in the air conditioner according to any one of the first to fourth aspects, a part of the main suction pipe on the branch suction pipe side is protruded into the oil reservoir. It is characterized by that.
In this air conditioner, the main suction pipe and the oil reservoir are doubled on the branch suction pipe side, and liquid oil flowing along the inner wall of the pipe is separated between the main suction pipe and the oil reservoir. It becomes easy to collect in between.

  According to the present invention, liquid oil is temporarily accumulated in the oil reservoir, the fluid discharged from the compressor is sucked as a driving flow, and is ejected from the two-fluid nozzle to the main suction pipe. Therefore, it becomes possible to make liquid oil into a mist state. Therefore, it becomes easy to mix in the gas refrigerant, and the oil sucked into each compressor can be properly distributed. In addition, the degree of freedom in piping design is improved, and even when compressors with different capacities are installed, it is possible to ensure the amount of oil returned according to the capacity. Here, when the oil separated by the oil separator is used as the driving flow, the oil can be efficiently recovered with a simple configuration. If the two-fluid nozzle is provided immediately before the branch portion of the branch suction pipe, it is possible to prevent oil drift due to the shape of the main suction pipe. Furthermore, if the oil reservoir and the main suction pipe have a double structure, the oil is easily retained.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the air conditioner 1 has a configuration in which an indoor unit 5 is connected to an outdoor unit 2 through pipes 3 and 4. The outdoor unit 2 includes a first compressor 10 and a second compressor 11 having a larger capacity than the first compressor 10, and the compressors 10 and 11 are connected by an oil equalizing pipe 12. The oil equalizing pipe 12 is not an essential component for the present embodiment. A discharge pipe 13 is connected to the discharge side of each compressor 10, 11, and the discharge pipe 13 is connected to a first port 15 </ b> A of the four-way valve 15 via an oil separator 14. A discharge path is formed by the discharge pipe 13 and the oil separator 14.

  One of the second port 15B and the third port 15C can be connected to the first port 15A of the four-way valve 15, and the fourth port 15D is correspondingly connected to the third port 15C or the second port 15C. 2 port 15B. The second port 15 </ b> B is connected to the outdoor heat exchanger 17 through the pipe 16, and the outdoor heat exchanger 17 is connected to the indoor heat exchanger 18 of the indoor unit 5 through the pipe 3. In this pipe 3, an expansion valve 19 is provided on the outdoor heat exchanger 17 side, and an expansion valve 20 is provided on the indoor heat exchanger 18 side. Further, the indoor heat exchanger 18 is connected to the third port 15C via the pipe 4. The fourth port 15 </ b> D is connected to the main suction pipe 21. The main suction pipe 21 includes a first branch suction pipe 23 connected to the suction side of the first compressor 10 at the main suction pipe branching portion 22 and a second branch suction connected to the suction side of the second compressor 11. Branches to the pipe 24.

  Here, an oil return pipe 25 is connected immediately before the main suction pipe branching portion 22 of the main suction pipe 21. The oil return pipe 25 allows oil separated from the high-pressure gas refrigerant by the oil separator 14 to flow therethrough, and is connected via the two-fluid nozzle 30 immediately before the main suction pipe branching portion 22 of the main suction pipe 21. ing. Further, the main suction pipe 21 is provided with an oil storage tank 40 that is an oil storage part on the four-way valve 15 side of the oil return pipe 25. As shown in FIG. 2, the oil storage tank 40 is connected to the main suction pipe 21, and after being expanded in a tapered shape from the four-way valve 15 (see FIG. 1) side of the main suction pipe 21, the oil storage tank 40 has a cylindrical shape. The main suction pipe 21 has an outer shape that extends again and tapers toward the main suction pipe branch 22 side. On the main suction pipe branch portion 22 side, a part of the main suction pipe 21 is in the oil storage tank 40. In this portion, the oil storage tank 40 and the main suction pipe 21 have a double pipe structure concentrically. Furthermore, in the cylindrical portion 40A of the oil storage tank 40, a pipe 41 extending in the radial direction and the outside is connected to the main suction pipe 21 and a portion having a double pipe structure, and on the lower side in the gravity direction. This pipe 41 is connected to the side of the two-fluid nozzle 30.

  The two-fluid nozzle 30 has an input port 31 having the same diameter as that of the oil return pipe 25, and a throttle portion 32 that reduces the diameter is provided at the tip of the input port 31. The throttle part 32 communicates with the mixing chamber 33 while maintaining its shape after being reduced in taper. The mixing chamber 33 is provided with a jet portion 34 that opens to the main suction pipe 21, and the jet portion 34 is provided with a taper that increases in diameter toward the main suction pipe 21. Further, a side hole 36 to which a pipe 41 is connected is provided at a side portion of the two-fluid nozzle 30, and the side hole 36 is communicated with an annular passage 37 provided so as to surround the throttle portion 32. Yes. The annular passage 37 communicates with the mixing chamber 33 via a communication hole 38 that surrounds the outer periphery of the opening of the throttle portion 32, and the flow passage area of the communication hole 38 is smaller than the flow passage area of the annular passage 37. It has become.

  As an example of the connection position between the oil return pipe 25 and the main suction pipe 21 as described above, the distance from the branch point where the refrigerant actually branches in the main suction pipe branching section 22 to the oil return pipe 25 is 50 mm or more. The main suction pipe 21 is preferably in a range where the main suction pipe 21 is not bent between the main suction pipe branching portion 22 and the connection point of the oil return pipe 25.

The operation of this embodiment will be described.
First, during the cooling operation, the first port 15A and the second port 15B of the four-way valve 15 are connected. The high-pressure gas refrigerant discharged from the first and second compressors 10 and 11 is supplied to the outdoor heat exchanger 17 through the four-way valve 15 after the oil is separated by the oil separator 14 through the discharge pipe 13. Is done. In the outdoor heat exchanger 17, a high-pressure liquid refrigerant is formed by heat exchange, and the liquid refrigerant is decompressed by the expansion valves 19 and 20 and then supplied to the indoor heat exchanger 18 of the indoor unit 5. And it evaporates by heat exchange with the indoor heat exchanger 18 to become a low-pressure gas refrigerant, and cools the room with the heat absorbed at this time. The gas refrigerant is guided from the pipe 4 to the main suction pipe 21 through the third and fourth ports 15C and 15D of the four-way valve 15, and from the main suction pipe branch portion 22 through the branch suction pipes 23 and 24. 1. It is sucked into the second compressors 10 and 11.

  During the heating operation, the first port 15A and the third port 15C of the four-way valve 15 are connected. The high-pressure gas refrigerant discharged from the first and second compressors 10 and 11 is supplied from the four-way valve 15 through the pipe 4 to the indoor heat exchanger 18 and condensed by heat exchange to become a high-pressure liquid refrigerant. At the same time, the room is heated by the heat released at this time. The liquid refrigerant is depressurized by the expansion valves 19 and 20 and then vaporized in the outdoor heat exchanger 17, and the second and fourth ports 15B and 15D, the main suction pipe 21, and the branch suction pipes 23 and 24 are connected to each other. It passes through and is collected by the first and second compressors 10 and 11.

  Here, in any of the operation modes, the oil discharged from the first and second compressors 10 and 11 is recovered by the oil separator 14, but some of the oil cannot be separated. Together with the gas refrigerant, the heat exchangers 17 and 18 are passed through and flow into the main suction pipe 21 from the fourth port 15D of the four-way valve 15. During this time, when a part of the oil is liquefied, it flows along the pipe wall of the main suction pipe 21 and enters the oil storage tank 40. The main suction pipe branching portion 22 side has a double pipe structure so that the oil storage tank 40 surrounds the outside of the main suction pipe 21 and is discontinuous. It cannot flow directly into the main intake pipe branching section 22 and stagnates in the cylindrical portion 40A of the oil storage tank 40 as an oil liquid film.

  On the other hand, the oil separated by the oil separator 14 and a small amount of high-pressure gas refrigerant (hereinafter simply referred to as oil) are guided to the main suction pipe 21 through the oil return pipe 25. The oil flowing through the oil return pipe 25 is guided from the input port 31 of the two-fluid nozzle 30 to the narrow-diameter restricting portion 32 and becomes a high-speed fluid when flowing through the restricting portion 32, and then the mixing chamber 33 passes through the mixing chamber 33. And is ejected from the ejection portion 34 to the main suction pipe 21. At this time, the oil is misted (miniaturized) and released into the main suction pipe 21, mixed with the low-pressure gas refrigerant, and immediately diverted from the main suction pipe branch portion 22 to the branch suction pipes 23 and 24, The air is sucked into the first and second compressors 10 and 11 as they are. At this time, in the two-fluid nozzle 30, when oil is ejected from the throttle portion 32 through the mixing chamber 33 at a high speed, the communication hole 38 surrounding the throttle portion 32 is decompressed, and the pipe communicates with the annular passage 37. The oil liquid film in the oil storage tank 40 is sucked from 41, sucked out from the annular passage 37 to the mixing chamber 33, mixed with the oil in the oil return pipe 25 in the mixing chamber 33, and becomes a mist state from the ejection portion 34. It is ejected to the suction pipe 21. The oil ejected in this way is mixed almost uniformly with the gas refrigerant, and is thus collected by the first and second compressors 10 and 11 according to the flow rates flowing through the branch intake pipes 23 and 24. The amount of oil also changes. That is, more gas refrigerant and oil are sucked into the second compressor 11 than the first compressor 10 in accordance with the capacity ratio.

  In this embodiment, an oil storage tank 40 is provided in the main suction pipe 21, and when the oil that could not be separated from the refrigerant is liquefied, the oil storage tank 40 is once retained and this oil liquid film is used as the oil storage film. The return oil collected by the separator 14 is sucked into the two-fluid nozzle 30 as a driving flow, and is misted together with the return oil from the oil separator 14 and sprayed to the main suction pipe 21. As in the prior art, unevenness in the return amount of oil that occurs when liquid oil passes through the main intake pipe branching portion 22 and flows into the intake branch pipes 23 and 24 is prevented. . Here, since the ejection part 34 of the two-fluid nozzle 30 is smaller than the diameter of the oil return pipe 25, it is possible to form a fine mist. It is possible to facilitate the suction into the second compressors 10 and 11. For this reason, it becomes possible to properly distribute oil, and even when the capacities of the first and second compressors 10 and 11 are different, it is possible to ensure an appropriate oil return amount according to the capacity ratio. it can.

  Further, since the main suction pipe 21 on the main suction pipe branching portion 22 side protrudes into the oil storage tank 40 and this portion has a double pipe structure, the liquid oil that flows along the pipe wall of the main suction pipe 21 Can be prevented from flowing directly into the main intake pipe branching section 22. Further, since the pipe 41 connected to the two-fluid nozzle 30 is provided at a portion where the oil storage tank 40 and the main suction pipe 21 overlap, the stagnant liquid oil can be sucked quickly, and the liquid oil Is prevented from flowing over the oil storage tank 40 into the main intake pipe branching section 22. Since the pipe 41 is connected to the lower side in the gravity direction, the oil liquid film accumulated in the oil reservoir tank 40 can be efficiently sucked.

  Here, instead of the oil return pipe 25, a branch pipe branched from the discharge pipe 13 is connected via a two-fluid nozzle 30 just before the main suction pipe branching portion 22 of the main suction pipe 21. Alternatively, a pipe 41 from the oil storage tank 40 may be connected. In this case, a part of the high-pressure gas refrigerant flowing through the discharge pipe 13 is ejected from the two-fluid nozzle 30 to the main suction pipe 21, and the oil liquid in the oil storage tank 40 is driven using this high-pressure gas refrigerant as a driving flow. Liquid oil is sucked from the membrane and ejected with the gas refrigerant. The branch pipe is desirably provided on the four-way valve 15 side of the oil separator 14, and the flow path resistance is sufficiently larger than the flow path resistance of the discharge pipe 13.

Note that the present invention can be widely applied without being limited to the above-described embodiment.
For example, the two compressors 10 and 11 may have the same capacity, or at least one of the compressors 10 and 11 may be a variable capacity type.
The oil return pipe 25 may be obliquely connected to the main suction pipe 21 so that the ejection part 34 of the two-fluid nozzle 30 faces the main suction pipe branching part 22. Further, the nozzle 30 can be connected so as to protrude into the main suction pipe 21.

It is a figure which shows the system configuration | structure of the air conditioning apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the connection with a main suction piping, an oil storage tank, and an oil return pipe. It is sectional drawing which shows the structure of the nozzle of an oil return pipe, and the connection structure with an oil storage tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 5 Indoor unit 10 1st compressor 11 2nd compressor 13 Discharge piping 14 Oil separator 17, 18 Heat exchanger 21 Main suction piping 22 Main suction piping branch part (branch part)
23, 24 Branch suction pipe 25 Oil return pipe 30 Two-fluid nozzle 40 Oil reservoir tank (oil reservoir)
41 Piping

Claims (5)

  A plurality of compressors arranged in parallel; a discharge pipe connected to a discharge side of the compressor; a heat exchanger of an outdoor unit to which a refrigerant discharged to the discharge pipe is supplied; and heat of the indoor unit An exchanger, a main suction pipe into which the refrigerant flowing through the heat exchanger flows, a branch suction pipe branched from the main suction pipe and connected to each of the compressors, and the main suction pipe An oil reservoir projecting so as to be able to store liquid oil, and a two-fluid nozzle that sucks the oil accumulated in the oil reservoir using the fluid divided from the discharge pipe as a driving flow and ejects the oil to the main suction pipe And an air conditioner.   The air conditioner according to claim 1, wherein the two-fluid nozzle is provided between the oil reservoir and a branch point of the branch suction pipe.   The air conditioner according to claim 2, wherein the two-fluid nozzle is provided immediately before a branch point of the branch suction pipe.   An oil separator is provided in the discharge pipe, an oil return pipe through which oil separated from the gas refrigerant by the oil separator is passed is connected to the two-fluid nozzle, and oil flowing through the oil return pipe is used as a driving flow. The air conditioner as described in any one of Claims 1-3 characterized by the above-mentioned. The air conditioner according to any one of claims 1 to 4, wherein a part of the main suction pipe on the branch suction pipe side is protruded into the oil reservoir.

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