WO2011064813A1

WO2011064813A1 - Accumulator and refrigeration cycle device

Info

Publication number: WO2011064813A1
Application number: PCT/JP2009/006331
Authority: WO
Inventors: 鳩村傑; 山下浩司; 森本裕之; 若本慎一; 下地美保子
Original assignee: 三菱電機株式会社
Priority date: 2009-11-25
Filing date: 2009-11-25
Publication date: 2011-06-03
Also published as: JPWO2011064813A1; JP5425221B2

Abstract

Disclosed are an accumulator and the like that can return oil without complicating circuit architecture or consuming energy. The disclosed accumulator (6) performs vapor-liquid separation and accumulates the liquid in order to supply a refrigerant in a vapor phase to a compressor (1) in a refrigeration cycle device. The accumulator is provided with: a vessel (A) for accumulating the liquid; an inflow pipe (B) via which a refrigerant, which circulates through a refrigeration circuit, flows into the vessel (A); a distribution coupling (G) for distributing, in a plurality of directions, the refrigerant which has flowed into the inflow pipe (B); a branching pipe (I) that leads the distributed refrigerant to the bottom of the vessel (A) such that the refrigerant agitates the liquid accumulated in the vessel (A); and an outflow pipe (C) that has an oil-return hole (D) out which the refrigerant flows along with refrigerant oil in the liquid accumulated in the vessel (A).

Description

Accumulator and refrigeration cycle apparatus

The present invention relates to an accumulator used in a refrigeration cycle apparatus. In particular, the present invention relates to an accumulator capable of returning oil even when a refrigerating machine oil incompatible with a refrigerant is used.

Conventionally, air conditioners that use chlorofluorocarbon refrigerants have been widely used as multi-air conditioners for buildings. In recent years, however, supercritical refrigeration cycle apparatuses that use supercritical fluids such as carbon dioxide (CO ₂ ) refrigerants have been used in recent years. Is considered to be installed in multi air conditioners for buildings.

Here, now, CO refrigerating machine oil used in the refrigeration cycle apparatus using _two refrigerant, the CO ₂ refrigerant is a refrigerating machine oil incompatible. In addition, there is no refrigeration oil that is compatible with the CO ₂ refrigerant in the entire operating temperature range used in the refrigeration cycle apparatus, such as chlorofluorocarbon refrigerant. The term “incompatible” as used herein means that the refrigerant and the refrigerating machine oil do not completely dissolve, and that the incompatible is completely incompatible, and the amount that is slightly soluble but the amount that is soluble is difficult. Contains both soluble ones. For example, in a refrigeration cycle apparatus that requires an accumulator to adjust the refrigerant amount during cooling or heating operations, such as a building multi-air conditioner, and the piping length of the system becomes long, if incompatible refrigerating machine oil is used, piping, heat There is a possibility that a lot of refrigerating machine oil stays in exchangers, accumulators, etc. In particular, when the refrigerant temperature is low (for example, the refrigerant temperature is −15 ° C. or lower) and the density of the refrigerating machine oil becomes lower than the density of the refrigerant, it is difficult to return the refrigerating machine oil staying in the accumulator. As a result, there was a shortage of oil return and the refrigerating machine oil in the compressor was exhausted, and the possibility that the compressor was damaged was high.

Here, the hot gas is bypassed from the compressor discharge side, the hot gas is allowed to flow into the lower part of the accumulator, and the refrigerant and refrigeration oil staying in a separated state in the lower part of the accumulator are agitated and mixed to return oil from the accumulator. There is also proposed a method that enables this (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2004-26395 (Claim 1, FIG. 1, etc.)

In the system as described in Patent Document 1, it is necessary to install a bypass pipe and a bypass on-off valve in the accumulator, which causes problems such as a complicated circuit configuration of the system and an increase in manufacturing cost. In addition, since the refrigerant discharged from the compressor is introduced into an accumulator installed on the suction side of the compressor, energy is wasted and there is a problem that energy saving cannot be achieved.

Therefore, it is an object of the present invention to obtain an accumulator that can perform oil return without complicating the circuit configuration and without consuming energy.

An accumulator according to the present invention performs gas-liquid separation in order to supply a gas-phase refrigerant to a compressor of a refrigeration cycle apparatus, and stores a liquid in the accumulator, and a refrigerator oil that circulates in a refrigerant circuit and a refrigerant circuit An inflow pipe for allowing the refrigerant containing the liquid to flow into the container, a distribution joint for distributing the refrigerant flowing into the inflow pipe into a plurality of parts, and guiding the distributed refrigerant to the lower part of the container and staying in the container by the refrigerant A branch pipe for stirring the liquid and an outflow pipe having an oil return hole for allowing the refrigeration oil in the liquid staying in the container to flow out together with the refrigerant are provided.

According to the present invention, the distribution joint and the branch pipe are connected to the inflow pipe, and the refrigerant is guided to the lower part of the container so as to stir the staying liquid. The refrigeration oil can be conveyed to the compressor along with the refrigerant from the outflow pipe. At this time, since a reliable oil return can be performed without requiring a complicated circuit and without adding valves or the like, a low-cost accumulator can be obtained without wasting energy.

It is a figure which shows the structure of the air conditioning apparatus which concerns on embodiment of this invention. It is a diagram showing a two-layer separation curves of CO ₂ refrigerant and PAG oil. It is a diagram showing a density comparison by the temperature change of the CO ₂ refrigerant and PAG oil. It is a figure showing the structure of the normal accumulator 60. FIG. 2 is a diagram illustrating a configuration of an accumulator 6 according to Embodiment 1. FIG. It is a figure showing the structure of the accumulator 6 which concerns on Embodiment 2. FIG. It is a figure showing the structure of the accumulator 6 which concerns on Embodiment 3. FIG. It is a figure showing the structure of the accumulator 6 which concerns on Embodiment 4. FIG.

Hereinafter, a refrigeration cycle apparatus according to an embodiment of the present invention will be described.

Embodiment 1 FIG.
1 is a diagram illustrating a configuration of an air-conditioning apparatus serving as a refrigeration cycle apparatus according to Embodiment 1. FIG. In the present embodiment, an air conditioner will be described as a representative refrigeration cycle apparatus. In FIG. 1, the air conditioner according to the present embodiment connects an outdoor unit 100 and indoor units 200a and 200b with a gas pipe 51 and a liquid pipe 52, and constitutes a refrigerant circuit in which refrigerant circulates. Then, inside this refrigerant circuit, for example, carbon dioxide that becomes a supercritical state at a critical temperature (about 31 ° C.) or higher as refrigerant and PAG (polyalkylene glycol) oil that is incompatible with carbon dioxide as refrigerating machine oil are enclosed. is doing.

The outdoor unit 100 is basically installed outdoors and houses the compressor 1, the flow path switching valve 2, the heat source side heat exchanger 3, the accumulator 6, the blower 7, and the control device 8. The compressor 1 compresses the gas refrigerant. For example, the flow path switching valve 2 such as a four-way valve is a refrigerant flow path switching unit that switches the direction in which the refrigerant flows in accordance with the operation mode of the indoor units 200a and 200b. The heat source side heat exchanger 3 functions as a radiator or an evaporator depending on the operation mode, and performs heat exchange between outdoor air (hereinafter referred to as outside air) and the refrigerant. The accumulator 6 can store surplus refrigerant or the like to adjust the amount of refrigerant circulating in the refrigerant circuit according to the operation mode. The blower 7 forcibly sends outside air to the outer surface of the heat source side heat exchanger 3 to promote heat exchange between the outside air and the refrigerant. The control device 8 controls the refrigerant circuit in cooperation with a control device (not shown) that controls the operation of the indoor units 200a and 200b, such as driving the compressor 1 and the blower 7, switching the flow path switching valve 2, and the like. I do. Although it is housed in the outdoor unit 100 here, it may be provided outside.

The indoor units 200a and 200b accommodate electronic expansion valves 4a and 4b, load-side heat exchangers 5a and 5b, and blowers 9a and 9b, respectively. The electronic expansion valves 4a and 4b serve as decompression means, and adjust the amount of refrigerant flowing through the load-side heat exchangers 5a and 5b by changing the opening, respectively, and adjust the refrigerant pressure and temperature in the load-side heat exchangers 5a and 5b. To do. The load side heat exchangers 5a and 5b have one end connected to the gas pipe 51 and the other end connected to the liquid pipe 52 via the electronic expansion valves 4a and 4b. The load-side heat exchangers 5a and 5b also function as radiators or evaporators depending on the operation mode, and exchange heat between the air in the air-conditioning target space and the refrigerant. If the heat source side heat exchanger 3 functions as a radiator, the load side heat exchangers 5a, 5b function as an evaporator, and if the heat source side heat exchanger 3 functions as an evaporator, the load side heat exchanger 5a, 5b functions as a radiator. The blowers 9a and 9b promote heat exchange between the air in the air-conditioning target space and the refrigerant in the load-side heat exchangers 5a and 5b, and send air related to heat exchange with the refrigerant into the air-conditioning target space. Here, in this embodiment, two indoor units 200a and 200b are provided, but one or three or more indoor units 200 may be connected by piping.

FIG. 2 is a diagram showing a two-layer separation curve of carbon dioxide and PAG oil. From FIG. 2, it can be seen that when the oil content is about 40% or less, carbon dioxide and PAG oil are separated into two layers in all temperature ranges. Since the oil content in the refrigerant circuit as in the present embodiment is about 10% to 20%, the carbon dioxide and the PAG oil are separated into two layers in the entire temperature region where the temperature of the refrigerant in the refrigerant circuit is reached.

FIG. 3 is a graph showing the relationship between the temperature, the density of the carbon dioxide liquid, and the density of the PAG oil. From FIG. 3, when the temperature of the liquid carbon dioxide (hereinafter referred to as carbon dioxide liquid) and the PAG oil is about −15 ° C. or less, the density of the carbon dioxide liquid becomes higher than the density of the PAG oil. For this reason, the carbon dioxide liquid becomes heavier than the PAG oil, and the PAG oil stays on top of the carbon dioxide liquid. Conversely, at a temperature higher than about −15 ° C., the PAG oil stays below the carbon dioxide solution.

FIG. 4 is a diagram for illustrating the structure of a normal accumulator 60. Here, a normal accumulator 60 will be described for comparison with the accumulator 6 of the present embodiment. The arrows represent the flow of refrigerant and refrigerating machine oil (hereinafter the same). The accumulator 60, the container A to be sealed, an inflow pipe B for allowing a mixture of refrigerant (liquid refrigerant and gas refrigerant) and refrigerating machine oil to flow into the container A, and a mixture of refrigerant and refrigerating machine oil to flow out of the container A. It is composed of a U-shaped outflow pipe C. The outflow pipe C has an oil return hole (oil return hole) D for returning the refrigeration oil at the lower part. The discharge port E is an opening portion of a pipe for discharging the inflowing refrigerant, and is here an opening portion of one end of the inflow tube B. Moreover, the intake port F is an opening part of the one end of the outflow pipe C for taking in the refrigerant to flow out. Here, the vertical relationship of the positions is defined as, for example, an upper side and a lower side with respect to the vertical direction.

And in order to prevent the liquid refrigerant which collides and scatters to the container A from flowing through the outflow pipe C, the discharge port E opened at one end of the inflow pipe B is more than the intake port F opened at one end of the outflow pipe C. Is also located on the lower side. Further, in order to carry the liquid refrigerant and the refrigerating machine oil while swirling to the lower part of the container A, the discharge port E in the inflow pipe B faces the inner wall of the container A in the vertical direction or faces downward. ing. In order to promote the separation of the gas refrigerant from the mixture of the liquid refrigerant and the refrigerating machine oil due to the collision, the gap between the outlet E in the inlet pipe B and the inner wall of the container A is equal to or larger than a certain value (for example, 2 of the inner diameter of the inlet pipe B). (Distance more than double). The distance between the oil return hole D and the bottom of the container A is made as short as possible in order to reduce the amount of refrigerating machine oil staying at the bottom of the container A (for example, a distance that can be managed in production). .

Most of the mixture of the refrigerant and the refrigerating machine oil that has flowed into the container A from the inflow pipe B collides with the inner wall of the container A, and is separated into a mixture of gas refrigerant, liquid refrigerant, and refrigerating machine oil (gas-liquid separation). The mixture of the gas refrigerant, the liquid refrigerant, and the refrigerating machine oil that could not be separated is almost separated into gas and liquid by flowing along the inner wall of the container A to the lower part of the container A (swirl flow). In the lower part of the container A, the liquid refrigerant and the refrigerating machine oil separate from each other and stay, and the gas refrigerant stays in the upper part. The gas refrigerant staying in the upper part of the container A flows out of the container A from the outflow pipe C. The liquid refrigerant and the refrigerating machine oil staying in the lower part of the container A are generated by the dynamic pressure of the gas refrigerant generated between the intake port F of the outflow pipe C and the oil return hole D and the height of the liquid level in the container A. Due to the difference, the oil is sucked from the oil return hole D and flows out of the container A together with the gas refrigerant.

Next, the amount of liquid in the accumulator 60 will be described. For example, in the cooling operation, the refrigerant whose amount is optimized is compressed to high temperature and high pressure by the compressor 1, passes through the flow path switching valve 2, is radiated by the heat source side heat exchanger 3, and exits the liquid pipe 52. Then, the gas refrigerant that has been decompressed by the electronic expansion valves 4a and 4b and obtained the set superheat degree (for example, 1 to 5 ° C.) at the outlets of the load side heat exchangers 5a and 5b passes through the gas pipe 51 to the accumulator 60. It flows in and is sucked into the compressor 1 again.

At this time, as described above, the liquid refrigerant and the high-concentration refrigerating machine oil each form a layer in the accumulator 60 and stay in the lower part in the container A. When the temperature is higher than −15 ° C., the refrigerating machine oil is heavier than the refrigerant. For this reason, in the container A, the refrigerating machine oil is located below the refrigerant, and as shown in FIG. 4 (a), the refrigerating machine oil is sucked from the oil return hole D installed in the lower part of the accumulator 60, Oil is returned to the compressor 1.

On the other hand, in the heating operation, the gas refrigerant is compressed to high temperature and high pressure by the compressor 1, passes through the flow path switching valve 2, exits the gas pipe 51, and then radiates heat in the load side heat exchangers 5 a and 5 b. Then, after the pressure is reduced by the electronic expansion valves 4 a and 4 b, the gas or the two-phase refrigerant evaporated at the outlet of the heat source side heat exchanger flows into the accumulator 60 through the liquid pipe 52. At this time, the surplus refrigerant (liquid refrigerant) and the refrigerating machine oil each form a layer and stay in the container A separated. When the density of the surplus refrigerant is smaller than that of the refrigerating machine oil (for example, the refrigerant temperature is −15 ° C. or higher), the refrigerating machine oil becomes heavier than the refrigerant. The oil is returned to the compressor 1 through the oil return hole D provided in.

However, when the density of the surplus refrigerant is larger than that of the refrigerating machine oil (for example, the refrigerant temperature is −15 ° C. or lower), the refrigerating machine oil becomes lighter than the liquid refrigerant, so that the refrigerating machine oil stays on top of the liquid refrigerant. At this time, as shown in FIG. 4B, if liquid refrigerant is present at the position of the oil return hole D provided in the lower part of the accumulator 60 (outflow pipe C), the refrigeration oil is returned to the compressor 1 from the oil return hole D. It becomes difficult to oil.

FIG. 5 is a diagram illustrating the structure of the accumulator 6 according to the first embodiment. In the accumulator 6 of the present embodiment, the liquid refrigerant staying in the lower part in the container A and the refrigerating machine oil that is incompatible with the refrigerant are prevented from forming a layer, and the density of the refrigerant is higher than the density of the refrigerating machine oil. Even in large environments, it is possible to return oil.

The container A, the inflow pipe B, the outflow pipe C, the oil return hole D, the discharge port E, and the intake port F are the same as the accumulator of FIG. However, the discharge port E is located at the opening of one end of the inflow branch pipe H. For example, the distribution joint G such as a Y-shaped joint or a T-shaped joint is a joint for distributing the mixture of the refrigerant and the refrigerating machine oil flowing in from the inflow pipe B to the inflow branch pipe H and the branch pipe I. The inflow branch pipe H performs gas-liquid separation into a mixture of gas refrigerant, liquid refrigerant, and refrigerating machine oil (will play the same role as the inflow pipe B in FIG. 4).

The branch pipe I is a pipe for directly feeding the mixture of the refrigerant and the refrigerating machine oil distributed by the distribution joint G in order to stir the liquid refrigerant and the refrigerating machine oil staying in the lower part in the container A into the lower part of the container A. is there. The agitation discharge port J is an opening portion of a pipe for discharging a mixture of the refrigerant and the refrigerating machine oil for stirring the liquid refrigerant and the refrigerating machine oil, and is here an opening part of one end of the branch pipe I. . The stirring outlet J is directed to face the inner wall of the bottom of the container A.

Here, the inner sectional area of the inflow branch pipe H is made larger than the inner sectional area of the branch pipe I. For example, in the present embodiment, the inner cross-sectional area of the inflow branch pipe H> A _in / 2 and the inner cross-sectional area of the branch pipe I <A _in / 2 with respect to the inlet inner cross-sectional area A _in of the inflow pipe B. Use a suitable pipe diameter. For this reason, the mixture of the refrigerant and the refrigerating machine oil can be prevented from flowing excessively to the branch pipe I side, and can be prevented from flowing to the inflow branch pipe H side to reduce the gas-liquid separation efficiency. . In addition, by maintaining an inner cross-sectional area equal to or greater than that of the inlet side of the inflow pipe B, it is possible to suppress an increase in pressure loss.

Also, the outlet E of the inflow branch pipe H is located at the upper part of the accumulator 6 (upper half part in the vertical direction), because the time required for turning becomes longer, so that the gas-liquid separation efficiency becomes higher. However, although the gas-liquid separation efficiency is somewhat lowered, the discharge port E may be provided below the accumulator 6. Furthermore, the branch pipe I is a thin pipe, and there is a risk of breaking due to vibration or the like. Therefore, for example, the branch pipe I is installed close to a portion of the outflow pipe C facing the vertical direction, and is fixed to the outflow pipe C with a fixture. And the intensity | strength of the branch piping I can be maintained by making the branch piping I and the outflow pipe C shake integrally with respect to a vibration.

As described above, in the accumulator in the air conditioner of Embodiment 1, the distribution joint G, the inflow branch pipe H, and the branch pipe I are connected to the inflow pipe B in the accumulator 6, and the refrigerant flowing from the inflow pipe B and the refrigeration Since the liquid refrigerant staying in the lower part in the container A and the refrigerating machine oil incompatible with the refrigerant are stirred by feeding the mixture with the machine oil so that the refrigerating machine oil is not retained in the upper part in the container A, the refrigerant, etc. Regardless of the temperature, the refrigeration oil can be transported to the oil return hole D and returned to the compressor 1. Further, the refrigerant ejected from the agitation outlet J is mixed with liquid refrigerant and gas refrigerant. By sending this gas refrigerant into the container A, the liquid refrigerant in the container A and the gas refrigerant sent in are mixed. Mixing and lowering the density of the refrigerant, which is a mixture of liquid and gas, makes it easier for the refrigerating machine oil to stay in the lower part of the container A, and has the effect of making it easier to return the refrigerating machine oil from the oil return hole D. Regardless of the temperature of the refrigerant or the like, the refrigeration oil can be transported to the oil return hole D and returned to the compressor 1. At this time, since the distribution joint G, the inflow branch pipe H, and the branch pipe I are connected to the inflow pipe B to realize oil return to the compressor 1, for example, a pipe connection with the discharge side of the compressor 1 The number of pipes connected to the outside can be reduced. For this reason, it is possible to manufacture the low-cost accumulator 6 without complicating the circuit configuration, adding valves, etc., and not consuming energy wastefully. In addition, since oil can be reliably returned regardless of temperature, it is possible to obtain a refrigeration cycle apparatus that can prevent oil depletion in the compressor 1 and improve safety and reliability.

Embodiment 2. FIG.
FIG. 6 is a diagram illustrating the structure of the accumulator 6 according to the second embodiment. In FIG. 6, the same reference numerals as those in FIG. 5 perform the same functions as those described in the first embodiment. In this embodiment, a distribution joint K, a branch pipe L, and a branch branch pipe M are further connected to the branch pipe I by piping.

The distribution joint K is a joint for distributing the mixture of the refrigerant and the refrigerating machine oil flowing in from the branch pipe I to the branch pipe L and the branch branch pipe M, similarly to the distribution joint G. The branch pipe L has a discharge port N at one end. When the amount of liquid refrigerant and refrigerating machine oil staying is large and the discharge port N is located below the liquid level, a mixture of refrigerant and refrigerating machine oil that stirs the liquid refrigerant and refrigerating machine oil is fed and stirred. It becomes the piping of. Further, when the discharge port N is located below the liquid level, similarly to the inflow branch pipe H, gas-liquid separation is performed into a mixture of gas refrigerant, liquid refrigerant, and refrigeration oil. For this reason, similarly to the discharge port E, the discharge port N faces the inner wall of the container A in the vertical direction or faces downward. The branch branch pipe M is a pipe that feeds a mixture of refrigerant and refrigerating machine oil and stirs the liquid refrigerant and refrigerating machine oil staying in the container A. In the present embodiment, it is assumed that a stirring outlet J is provided at one end of the branch branch pipe M.

Here, in order to suppress an increase in pressure loss and a decrease in gas-liquid separation efficiency, the sum of the inner sectional areas of the lowermost branch pipe L and branch branch pipe M and the inner sectional area of the branch pipe I are made equal. . In addition, the sum of the inner cross-sectional areas of the inflow branch pipe H and the branch pipe I is made equal to the inner cross-sectional area of the inflow pipe B. Furthermore, the inner sectional area of the branch pipe L is larger than the inner sectional area of the branch branch pipe J, and the inner sectional area of the inflow branch pipe H is larger than the inner sectional area of the branch pipe I. As a specific example, with respect to the inner cross-sectional area A _in of the inflow pipe B, the inner cross-sectional area of the inflow branch pipe H> A _in / 2, and the inner cross-sectional area of the branch pipe I <A _in / 2. Further, the inner sectional area of the branch pipe L> A _in / 4, and the inner sectional area of the branch pipe J <A _in / 4.

As described above, in the accumulator 6 in the air conditioner of Embodiment 2, the refrigerant that has been distributed by the distribution joint G and passed through the branch pipe I is further distributed to the branch pipe L and the branch branch pipe M by the distribution joint K. Thus, for example, when the amount of liquid refrigerant or the like staying in the accumulator 6 (container A) is small, the mixture is stirred by the mixture of the refrigerant and the refrigerating machine oil that has passed through the branch branch pipe M. When the amount of liquid refrigerant or the like is large, it can be agitated by a mixture of refrigerant and refrigerating machine oil that has passed through the branch pipe L, and even when the refrigerating machine oil retention position changes, the lower part of the accumulator Refrigerating machine oil can be transported to the installed oil return hole D. In addition, since the mixture of refrigerant and refrigerating machine oil is discharged from the outlet E of the inflow branch pipe H and the outlet N of the branch pipe L, gas-liquid separation by collision and gas-liquid separation by generating a swirl flow can be performed. Liquid refrigerant and refrigerating machine oil can be separated from gas refrigerant with almost no reduction in gas-liquid separation efficiency. Here, in the present embodiment, the two-stage branch in which only the branch pipe L and the branch branch pipe M are connected to the branch pipe I has been described, but three or more stages of branches may be performed.

Embodiment 3 FIG.
FIG. 7 is a diagram showing the structure of the accumulator 6 according to the third embodiment. In FIG. 7, the same reference numerals as those in FIG. 5 perform the same functions as those described in the first embodiment. The liquid suction hole O is a hole having a certain interval (for example, an interval of 20 mm) between one end J and the other end of the branch pipe I. In the present embodiment, three holes are formed, but a smaller or larger number of liquid suction holes O may be provided.

In addition, the inner cross-sectional area of the branch pipe I is made smaller than the inner cross-sectional area of the inflow pipe B, so that the pipe is contracted (for example, the inner cross-sectional area A _in of the inflow pipe B Cross-sectional area <A _in / 4). By contracting the branch pipe I, when the mixture of the refrigerant and the refrigerating machine oil flows into the branch pipe I from the inflow pipe B, the pressure is reduced and the flow velocity is increased. Due to the dynamic pressure generated in the liquid suction hole O and the pressure reduction by the contraction pipe, the pressure difference between the outside (inside the container A) and the inside (in the branch pipe I) of the liquid suction hole O (pressure in the container A—branch pipe) Pressure in I) occurs.

At this time, if the refrigerating machine oil staying in the container A covers the liquid suction hole O, it is sucked into the branch pipe I from the liquid suction hole O and discharged from the stirring outlet J of the branch pipe I. For this reason, refrigeration oil can be carried to the container A lower part, and refrigeration oil can be returned to the compressor 1 from the oil return hole D.

Here, the inner sectional area of the inflow branch pipe H is made larger than the inner sectional area of the branch pipe I. For example, in this embodiment, with respect to the inlet in the cross-sectional area A _in the inlet pipe B, the inner cross-sectional area ≧ A _in the inlet branch pipe H, the pipe such that the inner cross-sectional area <A _in / 4 of the branch pipe I Make the diameter. By adopting such a pipe diameter, the gas-liquid separation efficiency is lowered by flowing the mixture of the refrigerant and the refrigerating machine oil to the inflow branch pipe H side so as not to flow excessively to the branch pipe I side. To suppress that. Further, a cross-sectional area equal to or larger than that of the inlet of the inflow pipe B can be maintained, and an increase in pressure loss can be suppressed.

As described above, in the accumulator 6 of the air conditioner according to the third embodiment, the liquid suction hole O is inserted into the branch pipe I for feeding the mixture of the refrigerant and the refrigerating machine oil into the liquid refrigerant and the refrigerating machine oil staying in the container A. Since, for example, even when the refrigeration oil is located above the liquid refrigerant, the refrigeration oil can be sucked from the liquid suction hole O and sent to the lower part in the container A, so that the oil return hole D The oil return from can be promoted.

Embodiment 4 FIG.
FIG. 8 is a diagram illustrating the structure of the accumulator 6 according to the fourth embodiment. In FIG. 8, the same reference numerals as those in FIG. 5 perform the same functions as those described in the first embodiment. Here, structurally, the distribution joint G of the present embodiment is different from the above-described embodiment in that it is connected to the inflow pipe B, the inflow branch pipe H, and the branch pipe I outside the container A.

The solenoid valve P performs an opening / closing operation for allowing or not allowing refrigerant or the like to pass through the branch pipe I. The temperature detector Q detects the temperature of the refrigerant or the like flowing out from the outflow pipe C. For example, the control device 8 described above causes the solenoid valve P to perform an operation based on the temperature related to the detection of the temperature detector Q. The temperature detector Q may be installed at a position where the temperature of the refrigerant flowing into the accumulator can be detected, for example, the inflow pipe B.

As described above, the magnitude relationship between the density of the refrigerant and the density of the refrigerating machine oil changes at about −15 ° C., which is a low temperature environment. Therefore, for example, when the control device 8 determines that the temperature related to detection by the temperature detector Q is lower than a temperature (for example, −14 ° C.) just before reaching −15 ° C., the control device 8 opens the solenoid valve P, and the refrigerant In addition, the mixture of the refrigerating machine oil is allowed to pass through the branch pipe I, and the liquid refrigerant and the refrigerating machine oil that are staying are agitated.

On the other hand, when determining that the temperature related to detection by the temperature detector Q is -14 ° C. or higher, the control device 8 closes the solenoid valve P so that the mixture of refrigerant and refrigerating machine oil does not pass through the branch pipe I. To do. As a result, since the mixture of the refrigerant and the refrigerating machine oil all flows to the inflow branch pipe H side, the gas-liquid separation efficiency can be made equal to that of a normal accumulator.

Here, the inner cross-sectional area of the inflow branch pipe H is made equal to the inner cross-sectional area of the inlet pipe B. Further, the inner sectional area of the branch pipe I is made smaller than that of the inflow branch pipe H. For example, in this embodiment, with respect to the inlet in the cross-sectional area A _in the inlet pipe B, and the inner cross-sectional area of the inlet branch pipe H A _in, the tube diameter such that the inner cross-sectional area <A _in the branch pipe I To do. By setting it as such a pipe diameter, it becomes possible not to flow the mixture of a refrigerant | coolant and refrigerator oil to the branch piping I side excessively, and to suppress the increase in pressure loss.

As described above, according to the air conditioner of the fourth embodiment, the temperature detector Q for detecting the temperature of the refrigerant and the like, and the refrigerant to the branch pipe I based on the temperature related to the detection of the temperature detector Q. For example, in the lower part in the container A, the refrigerating machine oil is located below the liquid refrigerant and the oil return hole is not required to stir. When refrigerating machine oil can be returned from D to the compressor 1, the solenoid valve P can be closed. For this reason, the oil return which does not contain a liquid refrigerant can be performed, and the efficiency of oil return can be improved. Further, the circuit configuration is not complicated by installing the solenoid valve P in the accumulator 6 body.

Embodiment 5 FIG.
In the above-described embodiment, the case where the refrigerant in the refrigerant circuit is carbon dioxide and the refrigerating machine oil is PAG oil has been described as an example, but a combination of other refrigerants and refrigerating machine oil may be used. For example, the refrigerant may be a refrigerant such as a mixed refrigerant composed of carbon dioxide and an ether such as dimethyl ether or hydrofluoroether. In addition, the refrigerant is not limited to a supercritical state, but is a refrigerant that does not contain chlorine, such as an alternative refrigerant such as HFC410A and HFC407C, which is a refrigerant that performs heat exchange in a normal two-phase state, and a conventional Freon-based refrigerant such as R22 and R134a. Natural refrigerants such as refrigerants and hydrocarbons may be used. The refrigerating machine oil may be a refrigerating machine oil that is incompatible with each of these refrigerants.

In the embodiment described above, application to an air conditioner has been described. The present invention is not limited to these devices, and can also be applied to other refrigeration cycle devices that have an accumulator and constitute a refrigerant circuit.

1 compressor, 2 flow path switching valve, 3 heat source side heat exchanger, 4a, 4b electronic expansion valve, 5a, 5b load side heat exchanger, 6,60 accumulator, 7 blower, 8 control device, 9a, 9b blower, 51 gas pipe, 52 liquid pipe, 100 outdoor unit, 200a, 200b indoor unit, A container, B inlet pipe, C outlet pipe, D oil return hole, E outlet, F inlet, G distribution joint, H inlet branch Pipe, I branch pipe, J stirring outlet, K distribution joint, L branch pipe, M branch branch pipe, N outlet, O liquid suction hole, P solenoid valve, Q temperature detector.

Claims

In the accumulator that performs gas-liquid separation to supply the gas-phase refrigerant to the compressor of the refrigeration cycle apparatus and stores the liquid,
A container for storing the liquid;
An inflow pipe for allowing a refrigerant containing refrigerating machine oil circulating in the refrigerant circuit to flow into the container;
A distribution joint for distributing the refrigerant flowing into the inflow pipe into a plurality of parts;
A branch pipe for guiding the distributed refrigerant to the lower part of the container, and stirring the liquid retained in the container by the refrigerant;
An accumulator comprising an outflow pipe having an oil return hole for allowing the refrigeration oil in the liquid staying in the container to flow out together with the refrigerant.
There is a pipe for discharging a distributed refrigerant different from the refrigerant flowing through the branch pipe into the container, and the refrigerant outlet at one end of the pipe is on the upper half side of the space in the container The accumulator according to claim 1, wherein the accumulator is positioned.
The accumulator according to claim 1 or 2, wherein one or a plurality of distribution joints and pipes for further distributing the refrigerant flowing through the branch pipe are connected in multiple stages.
The accumulator according to any one of claims 1 to 3, wherein a plurality of through holes penetrating a pipe wall are provided in a pipe downstream of the branch pipe with respect to the refrigerant flow. .
The accumulator according to any one of claims 1 to 4, wherein the distribution joint and the branch pipe are connected in the container.
An opening / closing device for controlling passage of refrigerant in the branch pipe;
The accumulator according to any one of claims 1 to 4, wherein the opening / closing device is installed between the distribution joint connected outside the container and the branch pipe.
A temperature detector for detecting at least one of a temperature of the liquid staying in the container, a temperature of the liquid flowing into the container, or a temperature of the liquid flowing out of the container;
The switchgear is closed at a temperature at which the density of the liquid refrigerant in the lower part of the container is lower than the density of the refrigerating machine oil based on the temperature detected by the temperature detector, and the density of the liquid refrigerant in the lower part of the container is The accumulator according to claim 6, wherein the accumulator is controlled to open at a temperature higher than a density of machine oil.
The accumulator according to any one of claims 1 to 7, wherein the branch pipe is fixed to the outflow pipe.
A compressor that compresses the sucked refrigerant; a condenser that condenses the refrigerant by heat exchange; expansion means for depressurizing the condensed refrigerant; an evaporator that evaporates the decompressed refrigerant by heat exchange;
The refrigeration cycle constituting the refrigerant circuit for circulating the refrigerant by connecting the accumulator according to any one of claims 1 to 8 connected between the evaporator and the refrigerant suction side of the compressor. apparatus.
10. The refrigeration cycle apparatus according to claim 9, wherein the refrigerant is carbon dioxide, and the refrigerating machine oil is oil that is incompatible or hardly soluble with the refrigerant.