JP2012007864A - Liquid receiver and refrigerating cycle device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid receiver using oil which has oil density lower than refrigerant density and becomes non-compatible or weakly compatible in a low evaporation temperature region and can highly efficiently return oil to a compressor in a board operating condition.SOLUTION: An accumulator 50 includes: a first closed container 1; an inlet pipe 2 opened in an upper space of the first closed container 1; a first oil return pipe 5 opened in a lower space of the first closed container 1; a second closed container 6 provided on the downstream side of the first closed container 1; an overflow pipe 4 continued to the first closed container 1 and the second closed container 6 and having an upstream side opened at predetermined height within the first closed container 1 and a downstream side opened in an upper space of the second closed container 6; a second oil return pipe 9 opened in a lower space of the second closed container 6; an outlet pipe 3 opened in the upper space of the second closed container 6; and a refrigerant injection pipe 10 fluctuating the retention state of refrigerating machine oil and a refrigerant stored in the second closed container 6.

Description

  The present invention relates to a liquid receiver used as a component of a refrigeration cycle apparatus and a refrigeration cycle apparatus using the liquid receiver as a component.

  In general, in a refrigeration cycle apparatus such as an air conditioner, a liquid receiver is provided to absorb a change in the amount of refrigerant in the heat exchanger accompanying a change in operating conditions. As the liquid receiver, for example, an accumulator that is disposed on the suction side of the compressor and stores the refrigerant that has flowed out of the evaporator, a refrigerant that flows out of the condenser, is disposed at a position where the medium-pressure state refrigerant is conducted, or There are receivers for storing the refrigerant flowing out of the evaporator.

  Among these accumulators, in addition to the function of accumulating excess refrigerant during operation, the amount of liquid refrigerant flowing out is referred to as the liquid back resistance of the compressor (the liquid back flowing into the compressor is called the liquid back, and the liquid back rate = liquid Refrigerating machine oil discharged together with the refrigerant from the compressor without returning to a large amount inside the accumulator while returning to the compressor while keeping the refrigerant outflow amount / refrigerant circulation flow rate below the limit value) Is required. The surplus refrigerant amount varies depending on temperature conditions, the operating frequency of the compressor, and the like. The surplus refrigerant amount increases under low frequency and low evaporation temperature conditions where the refrigerant circulation flow rate decreases, and the surplus refrigerant amount decreases under high frequency and high evaporation temperature conditions where the refrigerant circulation amount increases.

  As a configuration of the conventional refrigeration cycle apparatus, a plurality of accumulators are arranged in series with the flow path and the wake-up side accumulator is positioned higher than the wake-up side accumulator. There has been proposed one in which the bottom of the accumulator on the side and the accumulator on the upstream side are connected via a circuit having a check valve (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 6-2957 (pages 3 to 4, FIG. 1)

  When a conventional accumulator is installed in a refrigeration cycle device and oil that has an oil density lower than the refrigerant density and becomes incompatible or weakly compatible in the low evaporation temperature range is applied as a refrigerating machine oil, the upper part of the liquid refrigerant in the accumulator Thus, there is a problem that the separated refrigeration oil cannot be returned to the compressor, and the sliding portion of the compressor is seized.

  The present invention has been made in order to solve the above-described problems, and uses a liquid receiver that can perform oil return to a compressor with high efficiency under a wide range of operating conditions, and the liquid receiver. The purpose is to provide a highly reliable refrigeration cycle apparatus.

  A liquid receiver according to the present invention includes a first liquid reservoir, an inlet pipe that opens to an upper space of the first liquid reservoir, a first oil return pipe that opens to a lower space of the first liquid reservoir, A second liquid reservoir provided downstream of the first liquid reservoir, overflow means communicating with the first liquid reservoir and the second liquid reservoir, and a lower space of the second liquid reservoir A second oil return pipe that is open to the outlet, an outlet pipe that is open to an upper space of the second liquid reservoir, an external input means that varies a residence state of the refrigerating machine oil and refrigerant stored in the second liquid reservoir, It is characterized by having.

  A refrigeration cycle apparatus according to the present invention includes at least the liquid receiver, the compressor, the condenser, the expansion device, and the evaporator.

  According to the liquid receiver according to the present invention, it is possible to achieve oil return to the compressor that matches the residence state of each temperature condition in the first liquid reservoir and the second liquid reservoir. Further, according to the refrigeration cycle apparatus according to the present invention, since the liquid receiver is provided on the suction side of the compressor, oil return to the compressor can be performed with high efficiency, and the sliding portion of the compressor Burn-in and the like can be suppressed, and the reliability becomes high.

It is a schematic longitudinal cross-sectional view which shows typically the cross-sectional structural example of the accumulator which concerns on Embodiment 1 of this invention. It is a circuit block diagram which shows typically the basic refrigerant circuit structure of the refrigerating-cycle apparatus using the accumulator which concerns on Embodiment 1 of this invention. The refrigerant | coolant state in the symbols AE shown in the refrigerant circuit shown in FIG. 2 is shown on the Ph diagram. It is explanatory drawing for demonstrating the flow pattern of the refrigerant | coolant and refrigerating machine oil of the accumulator which concerns on Embodiment 1 of this invention. It is a graph showing an example of the density characteristic of the refrigeration oil used for a refrigerating-cycle apparatus, and a refrigerant | coolant. It is explanatory drawing for demonstrating the typical flow pattern in the accumulator when evaporation temperature changes. It is a schematic longitudinal cross-sectional view which shows typically the cross-sectional structural example of the accumulator which concerns on Embodiment 2 of this invention. It is a circuit block diagram which shows typically the structure of the refrigerating-cycle apparatus provided with the accumulator which concerns on Embodiment 2 of this invention. It is a schematic longitudinal cross-sectional view which shows typically the cross-sectional structural example of the accumulator which concerns on Embodiment 3 of this invention. It is a circuit block diagram which shows typically the structure of the refrigerating-cycle apparatus provided with the accumulator which concerns on Embodiment 3 of this invention. It is a schematic longitudinal cross-sectional view which shows typically the cross-sectional structural example of the accumulator which concerns on Embodiment 4 of this invention. It is a schematic longitudinal cross-sectional view which shows typically the cross-sectional structural example of the accumulator which concerns on Embodiment 5 of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a schematic longitudinal sectional view schematically showing a cross-sectional configuration example of an accumulator 50 according to Embodiment 1 of the present invention. The configuration and operation of the accumulator 50 will be described with reference to FIG. FIG. 1 shows an example in which the liquid refrigerant 7 and the refrigerating machine oil 8 are stored in the accumulator 50. Moreover, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, in the following drawings including FIG. 1, the same reference numerals denote the same or equivalent parts, and this is common throughout the entire specification.

  The accumulator 50 according to the first embodiment is, for example, as one of component devices constituting a refrigeration cycle apparatus (described in FIG. 2) such as a refrigerator, a freezer, a vending machine, an air conditioner, a refrigeration apparatus, and a water heater. It is to be installed. This accumulator 50 is disposed on the suction side of a compressor (not shown) (compressor 55 shown in FIG. 2), and has a function of accumulating surplus refrigerant during operation and a liquid refrigerant outflow amount within the liquid back capacity of the compressor. However, it has a function of returning the refrigeration oil discharged from the compressor together with the refrigerant to the compressor.

  As shown in FIG. 1, the accumulator 50 includes a first sealed container (first liquid reservoir container) 1 and a second sealed container (second liquid reservoir container) 6, which are pressure containers, in series with respect to the refrigerant flow path. Connected to and configured. In FIG. 1, the liquid refrigerant 7 and the refrigerating machine oil 8 are separated into two layers and stored inside the first sealed container 1, and the liquid refrigerant 7 and the refrigerating machine oil 8 are turbidly stored inside the second sealed container 6. Has been. Hereinafter, the state in which the liquid refrigerant 7 and the refrigerating machine oil 8 are turbid is indicated by thick diagonal lines. The operation of the refrigerant in the accumulator 50 and the refrigerating machine oil 8 will be described in detail with reference to FIGS.

  The lower part of the first sealed container 1 and the upper part of the second sealed container 6 are connected by an overflow pipe 4 that functions as overflow means. That is, the first sealed container 1 and the second sealed container 6 communicate with each other through the overflow pipe 4. The upper end (upstream side) of the overflow pipe 4 opens at a predetermined height in the first sealed container 1, and the lower end (downstream side) opens at a predetermined height in the second sealed space 6. . In FIG. 1, the upper end portion and the lower end portion of the overflow pipe 4 are shown as an example in a state where they open to the upper space in the first sealed container 1 and the upper space in the second sealed container 6. In addition, although the opening height (the position of the upper end part of the overflow pipe 4) in the 1st airtight container 1 of the overflow pipe 4 is set to the suitable range by the structure and the operation range of an apparatus, details are shown in FIGS. This will be described with reference to FIG.

  An inlet pipe 2 is provided at the top of the first sealed container 1. The inlet pipe 2 has an end (lower end) that opens into the upper space of the first sealed container 1. A first oil return pipe 5 connected to the compressor suction side pipe is provided at the bottom of the first sealed container 1. The first oil return pipe 5 has an end portion (an end portion on the first sealed container 1 side) that opens into the lower space of the first sealed container 1. An outlet pipe 3 is provided on the side surface of the second sealed container 6. The outlet pipe 3 has an end portion (an end portion on the second sealed container 6 side) opened to the upper space. A second oil return pipe 9 connected to the compressor suction side pipe is provided at the bottom of the second sealed container 6. The second oil return pipe 9 is open to a lower space in the second sealed container 6.

  Further, in the lower space of the second hermetic container 6, a refrigerant injection pipe 10 is provided that has a refrigerant injection hole 11 that is connected to the compressor discharge side pipe and into which the high-temperature and high-pressure refrigerant is guided. The refrigerant injection pipe 10 functions as external input means for changing the staying state of the refrigerating machine oil and the liquid refrigerant stored in the second sealed container 6. In addition, as shown in FIG. 1, the piping which connects the compressor and the refrigerant | coolant injection pipe 10 is provided with the 1st on-off valve 15 which does not conduct a refrigerant | coolant by controlling opening and closing. Yes.

  FIG. 2 is a circuit configuration diagram schematically showing a basic refrigerant circuit configuration of the refrigeration cycle apparatus A using the accumulator 50 according to the first embodiment. Based on FIG. 2, the circuit configuration and operation of the refrigeration cycle apparatus A using the accumulator 50 according to Embodiment 1 will be described. The refrigeration cycle apparatus A is configured by connecting an outdoor unit (heat source unit) 100 and an indoor unit (load side unit) 200 by piping.

[Outdoor unit 100]
The outdoor unit 100 is installed outside, for example, a rooftop of a building, and has a function of supplying hot or cold to the indoor unit 200. In the outdoor unit 100, at least a compressor 55, a four-way valve 52 as a flow path switching unit, an outdoor heat exchanger (heat source side heat exchanger) 53, and an accumulator 50 are connected in series and mounted. Has been. The outdoor unit 100 may be provided with a blower such as a fan for forcibly supplying air to the outdoor heat exchanger 53 in the vicinity of the outdoor heat exchanger 53.

  Further, in the outdoor unit 100, a refrigerant that connects the discharge side pipe connected to the outlet side of the compressor 55 and the accumulator 50 (second sealed container 6) to the outlet side (discharge side) of the compressor 55. An injection pipe 10 is provided. A first on-off valve 15 is provided in the middle of the refrigerant injection pipe 10. The first on-off valve 15 is controlled to be opened and closed by a control means (two-layer separation detection) 23 based on pressure information or temperature information detected by a pressure detection means 21 or a temperature detection means 22 provided on the suction side of the accumulator 50. The

  The compressor 55 sucks refrigerant and compresses the refrigerant to bring it into a high temperature / high pressure state. The four-way valve 52 switches the refrigerant flow according to the operation mode of the indoor unit 200. The outdoor heat exchanger 53 functions as an evaporator or a radiator (condenser) according to the operation mode, performs heat exchange between air supplied from a blower (not shown) and the air conditioning refrigerant, and evaporates the refrigerant. It is gasified or condensed into liquid. The accumulator 50 is disposed on the suction side of the compressor 55 and stores excess refrigerant.

  The pressure detecting means 21 is provided on the suction side (upstream side) of the accumulator 50 and detects the pressure of the refrigerant flowing through this portion. The pressure information detected by the pressure detection means 21 is sent to the control means 23. The temperature detection means 22 is provided on the suction side (upstream side) of the accumulator 50 and detects the temperature of the refrigerant flowing through this portion. The temperature information detected by the temperature detection means 22 is sent to the control means 23. The control means 23 is composed of a microcomputer or the like, and based on detection information from various detection means and instructions from a remote controller (not shown), the driving frequency of the compressor 55, the rotation speed of the blower, the switching of the four-way valve 52, The opening degree of the expansion valve 57, which will be described later, and the opening / closing of the first opening / closing valve 15 are controlled.

[Indoor unit 200]
The indoor unit 200 is installed in an air-conditioning target space such as a living space, for example, and has a function of heating or cooling the air-conditioning target space by receiving the supply of hot or cold heat from the outdoor unit 100. The indoor unit 200 is mounted with at least an expansion valve 57 and an indoor heat exchanger (load side heat exchanger) 59 connected in series. The indoor unit 200 may be provided with a blower such as a fan for forcibly supplying air to the indoor heat exchanger 59 in the vicinity of the indoor heat exchanger 59.

  The expansion valve 57 expands the refrigerant by reducing the pressure. The expansion valve 57 may be configured by a valve whose opening degree can be variably controlled, for example, an electronic expansion valve. The indoor heat exchanger 59 functions as a radiator (condenser) and an evaporator, performs heat exchange between air supplied from a blower (not shown) and the air conditioning refrigerant, and condensates or evaporates the air conditioning refrigerant. It is gasified. The expansion valve 57 and the indoor heat exchanger 59 are connected in series.

  Here, the operation of the refrigeration cycle apparatus A will be described. First, the case where the indoor unit 200 performs the cooling operation will be described with reference to FIGS. 2 and 3. FIG. 3 shows on the Ph diagram the refrigerant states at symbols A to E shown in the refrigerant circuit shown in FIG. When the cooling operation is performed in the indoor unit 200, the four-way valve 52 of the outdoor unit 100 is set so that the first port 52a and the second port 52b communicate with each other and the third port 52c and the fourth port 52d communicate with each other ( (Indicated by a solid line in FIG. 3). In FIG. 3, the vertical axis represents the refrigerant pressure and the horizontal axis represents the specific enthalpy. Point A → point E shown in FIG. 3 corresponds to point A to point E in the circuit diagram of FIG.

Moreover, as a refrigerant to be used, CO ₂ that is in a supercritical state at a critical temperature (about 31 ° C.) or higher is assumed, and the refrigerant state in this case is shown in the Ph diagram of FIG. Further, as the refrigerating machine oil, oil whose oil density is smaller than the liquid refrigerant density in the low evaporation temperature region and which becomes incompatible or weakly compatible is enclosed. Note that the refrigerant is not limited to CO ₂ .

  The low-temperature and low-pressure refrigerant is compressed by the compressor 55 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 55 passes from the first port 52a of the four-way valve 52 through the second port 52b (state A) and flows into the outdoor heat exchanger 53. Then, the outdoor heat exchanger 53 radiates heat to the medium to be heated (for example, outdoor air) (state B), and becomes a liquid refrigerant. The liquid refrigerant that has flowed out of the outdoor heat exchanger 53 flows out of the outdoor unit 100 and flows into the indoor unit 200.

  The liquid refrigerant flowing into the indoor unit 200 is decompressed by the expansion valve 57 and then flows into the indoor heat exchanger 59 (state C). The refrigerant flowing into the indoor heat exchanger 59 processes the heat load of the air-conditioning target space. That is, the refrigerant flowing into the indoor heat exchanger 59 absorbs heat from the room air, and becomes a low-temperature and low-pressure gas refrigerant while cooling the room air. Thereafter, it also flows out from the indoor unit 200 and flows into the outdoor unit 100. The refrigerant that has flowed into the outdoor unit 100 flows from the fourth port 52d of the four-way valve 52 through the third port 52c into the first sealed container 1 via the inlet pipe 2 of the accumulator 50 (state D). . At this time, the refrigerant and the refrigerating machine oil flowing into the accumulator 50 are separated into gas and liquid in the accumulator 50 and then flow into the compressor 55 (state E).

  The superheat shown in FIG. 3 represents the state of the refrigerant sucked into the compressor 55. When superheat can be taken, the refrigerating machine oil and the refrigerant flowing into the accumulator 50 are in a mixed state of the refrigerating machine oil and the gas refrigerant. The gas refrigerant is sucked into the compressor 55 from the inlet pipe 2 connected to the accumulator 50 through the outlet pipe 3. When superheat cannot be obtained, the refrigerant oil, liquid refrigerant, and gas refrigerant (two-phase flow) are mixed. The gas refrigerant is sucked into the compressor 55 from the inlet pipe 2 connected to the accumulator 50 through the outlet pipe 3. On the other hand, the refrigeration oil and the liquid refrigerant flow into the outlet pipe 3 through the first oil return pipe 5 and the second oil return pipe 9 and are sucked into the compressor 55. In addition, operation | movement and control of the 1st on-off valve 15 are demonstrated in detail in FIGS.

  When heating operation is performed in the indoor unit 200, the four-way valve 52 is switched as indicated by a broken line. As a result, the outdoor heat exchanger 53 and the accumulator 50 are communicated, and the discharge side of the compressor 55 and the indoor heat are communicated. The exchanger 59 communicates. Even during the heating operation, the behavior of the refrigerating machine oil and the refrigerant flowing into the accumulator 50 with respect to the superheat state is the same as that during the cooling operation.

  FIG. 4 is an explanatory diagram for explaining a flow pattern of the refrigerant and the refrigerating machine oil of the accumulator 50 according to the first embodiment. FIG. 5 is a graph showing an example of density characteristics of refrigeration oil and refrigerant used in the refrigeration cycle apparatus A. Based on FIG.4 and FIG.5, operation | movement of the accumulator 50 is demonstrated. In FIG. 4, the dotted arrow indicates the flow of the gas refrigerant, the black arrow indicates the flow of the refrigerating machine oil, the white arrow indicates the flow of the liquid refrigerant, and the hatched arrow indicates the flow of the gas refrigerant in the high temperature and high pressure state. ing. Further, FIG. 4 shows an example in which the liquid refrigerant 7 and the refrigerating machine oil 8 are separated into two layers.

  Refrigerating machine oil used in the refrigeration cycle apparatus A has, for example, density characteristics as shown in FIG. 5 and becomes incompatible or weakly compatible (for example, HAB oil (hard alkylbenzene oil) or PAG (poly Alkylene glycol) etc. may be applied. When the oil having such properties is used as the refrigerating machine oil, the refrigerating machine oil and the excess refrigerant are separated into a liquid layer having a high oil concentration and a liquid layer having a low oil concentration and staying in the accumulator 50 in a low evaporation temperature range. Will do. Hereinafter, the liquid layer having a high oil concentration is referred to as refrigeration oil 8, and the liquid layer having a low oil concentration is referred to as liquid refrigerant 7. The flow of the refrigeration oil and the refrigerant will be described.

  The refrigeration oil and refrigerant discharged from the compressor 55 circulate in the refrigeration cycle and flow into the first sealed container 1 from the inlet pipe 2 of the accumulator 50. As shown in FIG. 4, when the refrigerating machine oil and the refrigerant flow into the accumulator 50, the refrigerating machine oil and the liquid refrigerant are separated from each other in the upper space of the first sealed container 1 and are retained in the lower part of the first sealed container 1. The Under conditions where the evaporation temperature is low, the circulation flow rate of the refrigerant flowing through the refrigeration cycle circuit is small, and a large amount of excess refrigerant stays in the accumulator 50. When the density of the refrigerating machine oil is equal to or lower than the evaporation temperature at which the density of the refrigerating machine oil and the density of the liquid refrigerant are reversed (the density reversal temperature shown in FIG. 5 is different depending on the type of refrigerant and the type of refrigerating machine oil), Since it becomes smaller than the density of the liquid refrigerant 7, it separates into the upper layer of the liquid refrigerant 7, and the refrigerating machine oil 8 stays there.

  Here, the opening height of the overflow pipe 4 (the opening height in the first sealed container 1) is set to be lower than the height of the minimum surplus refrigerant under the evaporation temperature condition that is equal to or lower than the density inversion temperature. Therefore, the refrigerating machine oil 8 separated into the upper layer of the liquid refrigerant 7 overflows from the opening end of the overflow pipe 4 together with the gas refrigerant flowing in from the inlet pipe 2, that is, flows into the second sealed container 6 through the overflow pipe 4. It will be. That is, surplus refrigerant and refrigerating machine oil that cannot be stored in the first sealed container 1 stay in the second sealed container 6. Since a large amount of excess refrigerant is stored in the first sealed container 1, the ratio of the liquid refrigerant stored in the second sealed container 6 and the refrigerating machine oil is higher than that in the case of storing in one sealed container. (Oil rich) state.

  The control means 23 controls the opening / closing of the first on-off valve 15 based on the pressure or temperature on the suction side of the accumulator 50 detected by the pressure detection means 21 or the temperature detection means 22. The control means 23 is configured such that the pressure or temperature on the suction side of the accumulator 50 detected by the pressure detection means 21 or the temperature detection means 22 is equal to or lower than a predetermined value (for example, in the case of temperature detection, a value smaller than the density reversal temperature value + 5K, etc.) ), The first on-off valve 15 is controlled to open. That is, the control unit 23 determines the state of the refrigerating machine oil and the refrigerant staying in the second sealed container 6 based on the pressure or temperature on the suction side of the accumulator 50 detected by the pressure detection unit 21 or the temperature detection unit 22, The opening and closing of the first on-off valve 15 is controlled.

  When the first on-off valve 15 is opened, the high-temperature / high-pressure gas refrigerant discharged from the compressor 55 flows into the refrigerant injection pipe 10 and enters the second sealed container 6 from the refrigerant injection hole 11 provided in the refrigerant injection pipe 10. It will be injected to the lower part. When the high-temperature and high-pressure gas refrigerant is injected from the refrigerant injection hole 11, the liquid refrigerant layer and the oil layer can be stirred in the second sealed container 6 to eliminate the layer separation state. Accordingly, the liquid refrigerant is sucked from the first oil return pipe 5 due to the pressure loss of the liquid head and the refrigerant staying in the first sealed container 1, and the mixed liquid of the refrigerating machine oil and the liquid refrigerant is sucked from the second oil return pipe 9. It is.

  From the above, in the refrigeration cycle apparatus A, the liquid refrigerant and the refrigerating machine oil are agitated and mixed in a state where the amount of the liquid refrigerant in the second sealed container 6 is reduced, so that the power necessary for eliminating the layer separation state ( Here, the compression power for the amount of the injected gas is small, and the refrigerating machine oil can be reliably recovered while suppressing the performance degradation.

  FIG. 6 is an explanatory diagram for explaining a typical flow pattern in the accumulator 50 when the evaporation temperature changes. Based on FIG. 6, the flow pattern of the refrigerating machine oil and the refrigerant in the accumulator 50 when the evaporation temperature changes will be described. In FIG. 6, the evaporation temperature is represented as a horizontal axis. FIG. 6 (a) shows a flow pattern under a condition where the evaporation temperature is low, FIG. 6 (b) shows a flow pattern when the evaporation temperature is around 0 ° C., and FIG. 6 (c) shows a flow pattern under a condition where the evaporation temperature is high. Represents. Similarly to FIG. 4, the dotted arrow indicates the flow of the gas refrigerant, the black arrow indicates the flow of the refrigerating machine oil, the white arrow indicates the flow of the liquid refrigerant, the hatched arrow indicates the flow of the gas refrigerant in the high temperature / high pressure state, Respectively.

  Under the conditions shown in FIG. 6A, the evaporation temperature is lower than the density inversion temperature, the amount of surplus refrigerant is large, and the refrigerating machine oil comes to float on the upper layer of the liquid refrigerant. Under such conditions, as described above, surplus refrigerant is basically stored in the first sealed container 1, and in the second sealed container 6, the amount of storage is reduced and an oil-rich state is created to add agitation power. And refrigeration oil is recovered from the second oil return pipe 9.

  Under the conditions shown in FIG. 6B, the evaporation temperature becomes higher than the density inversion temperature, and the refrigerating machine oil 8 is separated into the lower layer of the liquid refrigerant 7. That is, compared with the conditions shown in FIG. 6A, the refrigerant circulation amount increases and the surplus refrigerant amount decreases. Under such conditions, refrigeration oil having a high concentration flows from the first oil return pipe 5 and is sucked into the compressor 55 through the outlet pipe 3. The liquid refrigerant overflowed from the first closed container 1 flows into the second sealed container 6 and the liquid refrigerant stays. The liquid refrigerant flows out from the second oil return pipe 9, but the liquid head is small and the liquid back rate is reduced. At this time, since the evaporation temperature is higher than the density reversal temperature, the first on-off valve 15 is closed and there is no power loss.

  Under the conditions shown in FIG. 6C, the evaporation temperature is further increased, and only the refrigerating machine oil stays in the first sealed container 1. Under such conditions, there is no excess refrigerant and the liquid head is small. On the other hand, the refrigerant circulation flow rate is large, and the amount of oil outflow from the compressor 55 is large. That is, it is necessary to perform oil return with a small liquid head, but the pressure loss increases in proportion to the square of the flow velocity. Therefore, when the refrigerant circulation amount increases, a large suction force acts on the first oil return pipe 5, and the small liquid Oil can be returned even with the head. Also at this time, as in FIG. 6B, since the evaporation temperature is higher than the density inversion temperature, the first on-off valve 15 is closed and there is no power loss.

  In the first embodiment, as shown in FIG. 5, an example in which a refrigerating machine oil whose oil density is lower than the liquid refrigerant density and incompatible or weakly compatible in a low evaporation temperature range is shown. However, the present invention is not limited to this. That is, even when the compatible refrigerating machine oil is used, a layer having a high oil concentration temporarily separates into a layer having a low oil concentration under a low temperature condition (for example, when the refrigeration cycle apparatus A is stopped). Therefore, the same effect can be expected even if the features of the first embodiment are applied to the compatible refrigerating machine oil.

  As described above, according to the accumulator 50 according to the first embodiment, even when the high oil concentration layer and the low oil concentration layer are reversed, it is possible to add to the compressor 55 only by adding small power. Oil return can be realized. That is, since only a small amount of power is added under limited conditions, oil return to the compressor 55 can be efficiently realized in a wide operating range. Therefore, since the refrigeration cycle apparatus A includes the accumulator 50, the refrigeration cycle apparatus A has high performance and high reliability with no seizure of the sliding portion of the compressor 55.

  In the first embodiment, the refrigerant injection pipe 10 is connected to the discharge side of the compressor 55, and the high-temperature and high-pressure gas refrigerant is guided to the refrigerant injection pipe 10. However, the present invention is not limited to this. That is, if the upstream side connection portion of the refrigerant injection pipe 10 is higher than the pressure in the second sealed container 6 in the refrigeration cycle apparatus A, the same effect can be obtained even if it is connected to another pressure pipe or pressure container. It is done. In the first embodiment, the refrigerant injection pipe 10 is protruded into the second sealed container 6 so that the plurality of refrigerant injection holes 11 are arranged in the second sealed container 6. Even if it is connected to the outer peripheral surface 6, the same effect can be obtained.

Embodiment 2.
FIG. 7 is a schematic longitudinal sectional view schematically showing a sectional configuration example of the accumulator 50B according to the second embodiment of the present invention. FIG. 8 is a circuit configuration diagram schematically showing the configuration of the refrigeration cycle apparatus B including the accumulator 50B according to the second embodiment. With reference to FIG. 6, the characteristic items of the accumulator 50 </ b> B according to the second embodiment will be described based on FIGS. 7 and 8. FIG. 7 shows an example in which the liquid refrigerant 7 and the refrigerating machine oil 8 are stored in the accumulator 50B. Further, in the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and differences from the first embodiment will be mainly described.

  The accumulator 50B and the refrigeration cycle apparatus B according to the second embodiment are different from the accumulator 50 and the refrigeration cycle apparatus A according to the first embodiment in that a second opening / closing valve 16 is provided in the first oil return pipe 5. ing. Under the evaporation temperature condition lower than the density reversal temperature shown in FIG. 6A, excess refrigerant is stored in the first sealed container 1 and the liquid head is large, so that a large amount of liquid is transferred from the first oil return pipe 5 to the compressor 55. Then, a large amount of liquid refrigerant is supplied to the sliding portion of the compressor 55, which may reduce the durability of the bearing.

  Therefore, in the second embodiment, the second opening / closing valve 16 is provided in the first oil return pipe 5. The control means 23 controls the opening / closing of the second on-off valve 16 based on the pressure or temperature on the suction side of the accumulator 50B detected by the pressure detection means 21 or the temperature detection means 22 shown in FIG. The control means 23 is configured such that the pressure or temperature on the suction side of the accumulator 50B detected by the pressure detection means 21 or the temperature detection means 22 is a predetermined value or less (for example, in the case of temperature detection, a value smaller than the density reversal temperature value + 5K, etc.) ), The second on-off valve 16 is controlled to be closed. That is, the control means 23 determines the state of the refrigerating machine oil and the refrigerant staying in the second sealed container 6 based on the pressure or temperature on the suction side of the accumulator 50B detected by the pressure detection means 21 or the temperature detection means 22, The opening and closing of the second on-off valve 16 is controlled.

  Therefore, according to the accumulator 50B and the refrigeration cycle apparatus B according to the second embodiment, in addition to the effects described in the first embodiment, even in an evaporation temperature condition lower than the density inversion temperature shown in FIG. Since the liquid refrigerant does not flow out from the one oil return pipe 5, there is an effect that the liquid back rate can be greatly reduced.

Embodiment 3.
FIG. 9 is a schematic longitudinal sectional view schematically showing a sectional configuration example of an accumulator 50C according to Embodiment 3 of the present invention. FIG. 10 is a circuit configuration diagram schematically showing the configuration of the refrigeration cycle apparatus C including the accumulator 50C according to the third embodiment. Based on FIG.9 and FIG.10, the characteristic matter of the accumulator 50C which concerns on Embodiment 3 is demonstrated. FIG. 9 shows an example in which the liquid refrigerant 7 and the refrigerating machine oil 8 are stored in the accumulator 50C. Further, in the third embodiment, the same reference numerals are given to the same parts as those in the first and second embodiments, and differences from the first and second embodiments will be mainly described.

  The accumulator 50C according to the third embodiment eliminates the layer separation between the liquid refrigerant stored in the second hermetic container 6 and the refrigerating machine oil under the condition that the evaporation temperature is lower than the density inversion temperature (see FIG. 6A). This is different from the accumulator 50 according to the first embodiment and the accumulator 50B according to the second embodiment in that a heater 12 which is a kind of heating device is provided outside the second sealed container 6 as a mechanism for is doing. The heater 12 functions as external input means for changing the staying state of the refrigerating machine oil and the liquid refrigerant stored in the second sealed container 6. Therefore, in the accumulator 50 </ b> C, the refrigerant injection pipe 10 is not connected to the second sealed container 6.

  As shown in FIG. 9, the accumulator 50 </ b> C is provided with the heater 12 on the outer periphery of the second sealed container 6. The control means 23 controls the energization of the heater 12 by the pressure or temperature on the suction side of the accumulator 50C detected by the pressure detection means 21 or the temperature detection means 22 shown in FIG. The control means 23 is configured such that the pressure or temperature on the suction side of the accumulator 50C detected by the pressure detection means 21 or the temperature detection means 22 is a predetermined value or less (for example, in the case of temperature detection, a value smaller than the density reversal temperature value + 5K, etc.) ), The heater 12 is controlled to heat the second sealed container 6. That is, the control unit 23 determines the state of the refrigerating machine oil and the refrigerant remaining in the second sealed container 6 based on the pressure or temperature on the suction side of the accumulator 50C detected by the pressure detection unit 21 or the temperature detection unit 22, The heater 12 is controlled.

  When the second airtight container 6 is heated by the heater 12, a temperature difference is generated in the second airtight container 6, and convection (arrow in the figure) occurs in the liquid stored in the second airtight container 6. The separated layer state will collapse. In Embodiment 3, refrigeration oil is recovered from the second oil return pipe 9 by utilizing this phenomenon.

  Therefore, according to the accumulator 50C and the refrigeration cycle apparatus C according to the third embodiment, in addition to the effects described in the first and second embodiments, in the second sealed container 6 as in the first embodiment. Since heating by the heater 12 is performed in a state where the amount of liquid refrigerant is reduced, the heater input necessary to eliminate the layer separation state is small, and there is an effect that the refrigerating machine oil can be recovered while suppressing a decrease in performance. .

Embodiment 4.
FIG. 11 is a schematic longitudinal sectional view schematically showing a sectional configuration example of an accumulator 50D according to the fourth embodiment of the present invention. Based on FIG. 11, the characteristic matter of the accumulator 50D which concerns on Embodiment 4 is demonstrated. FIG. 11 shows an example in which the liquid refrigerant 7 and the refrigerating machine oil 8 are stored in the accumulator 50D. Further, in the fourth embodiment, the same reference numerals are given to the same portions as those in the first to third embodiments, and differences from the first to third embodiments will be mainly described.

  The accumulator 50D according to the fourth embodiment is the first to the second embodiments in that the partition plate 4a is horizontally installed in the sealed container 1A and the inside of the sealed container 1A is divided into the first space 1a and the second space 6a. This is different from the accumulator 50, accumulator 50B, and accumulator 50C according to the third embodiment. That is, in the first to third embodiments, the first sealed container 1 and the second sealed container 6 are separated from each other. However, in the fourth embodiment, the inside of one sealed container is partitioned. A first space 1a corresponding to the first sealed container 1 and a second space 6a corresponding to the second sealed container 6 are formed, and the same configuration as in the first to third embodiments is realized.

  Therefore, according to the accumulator 50D according to the fourth embodiment, in addition to the effects described in the first to third embodiments, the accumulator 50D can be configured with one sealed container 1A, so that the accumulator itself can be made compact. it can. Moreover, according to the refrigerating cycle apparatus provided with accumulator 50D, weight reduction and space saving can be achieved with the compactness of accumulator 50D.

Embodiment 5.
FIG. 12 is a schematic longitudinal sectional view schematically showing a sectional configuration example of an accumulator 50E according to Embodiment 5 of the present invention. Based on FIG. 12, the characteristic matter of the accumulator 50E which concerns on Embodiment 5 is demonstrated. In addition, in FIG. 12, the state which has stored the liquid refrigerant 7 and the refrigerating machine oil 8 in the accumulator 50E is shown as an example. In the fifth embodiment, the same parts as those in the first to fourth embodiments are denoted by the same reference numerals, and differences from the first to fourth embodiments will be mainly described.

  The accumulator 50E according to Embodiment 5 vertically installs a partition plate 4a having an opening 4b at a predetermined height in the sealed container 1B, and the left and right spaces (the space on the right side of the paper is the space). The embodiment in that the first space 1a1 (corresponding to the first space 1a of the fourth embodiment) and the space on the right side of the page are divided into the second space 6a1 (corresponding to the second space 6a of the fourth embodiment). 4 is different from the accumulator 50D. That is, in the fourth embodiment, the state in which the first space 1a and the second space 6a are arranged vertically is shown, but in the fifth embodiment, the first space 1a and the second space 6a are horizontal. It is arranged in.

  Therefore, in the accumulator 50E according to the fifth embodiment, the partition plate 4a is provided so as to divide one sealed container 1B into the left and right, and the opening 4b is provided at a predetermined height of the partition plate 4a. The function of 4 overflow pipes 4 is provided. That is, the opening 4b functions as overflow means. Therefore, according to the accumulator 50E which concerns on Embodiment 5, in addition to the effect demonstrated in Embodiment 1- Embodiment 4, the partition in the airtight container 1B and an overflow pipe are made into one component (partition plate 4a). Therefore, it can be configured with one sealed container 1B, the number of parts can be reduced, and it becomes compact and low cost.

  In addition, although embodiment of this invention was divided and demonstrated, you may make it combine each embodiment suitably. If the embodiments are appropriately combined, the effects of the features of the embodiments can be obtained in a superimposed manner.

  DESCRIPTION OF SYMBOLS 1 1st airtight container, 1A airtight container, 1B airtight container, 1a 1st space, 1a1 1st space, 2 inlet pipe, 3 outlet pipe, 4 overflow pipe, 4a partition plate, 4b opening part, 1st oil return pipe, 6 second sealed container, 6a second space, 6a1 second space, 7 liquid refrigerant, 8 refrigerating machine oil, 9 second oil return pipe, 10 refrigerant injection pipe, 11 refrigerant injection hole, 12 heater, 15 first on-off valve, 16 Second open / close valve, 21 Pressure detection means, 22 Temperature detection means, 23 Control means, 50 Accumulator, 50B Accumulator, 50C Accumulator, 50D Accumulator, 50E Accumulator, 52 Four-way valve, 52a First opening, 52b 2nd port, 52c 3rd port, 52d 4th port, 53 Outdoor heat exchanger, 55 Compressor, 57 Expansion valve, 59 Indoor heat exchanger, 00 outdoor unit, 200 indoor unit, A refrigeration cycle apparatus, B refrigeration cycle apparatus, C refrigeration cycle apparatus.

Claims (14)

A first liquid reservoir;
An inlet pipe opening into the upper space of the first liquid reservoir;
A first oil return pipe that opens into a lower space of the first liquid reservoir;
A second liquid reservoir provided downstream of the first liquid reservoir;
Overflow means communicating with the first liquid reservoir and the second liquid reservoir;
A second oil return pipe that opens into a lower space of the second liquid reservoir;
An outlet pipe opening into the upper space of the second liquid reservoir;
A liquid receiver, comprising: refrigerating machine oil stored in the second liquid storage container; and external input means for changing a retention state of the refrigerant. The first liquid reservoir and the second liquid reservoir are
The liquid receiver according to claim 1, wherein each liquid receiver is composed of an independent sealed container. The first liquid reservoir and the second liquid reservoir are
The liquid receiver according to claim 1, wherein one sealed container is configured by a first space and a second space separated by a partition plate. The overflow means is constituted by a pipe having an upstream side opened to a predetermined height in the first liquid reservoir and a downstream side opened to an upper space of the second liquid reservoir. The liquid receiver as described in any one of 1-3. The liquid receiver according to claim 3, wherein the overflow unit is configured by an opening provided in the partition plate that divides the first space and the second space. The liquid receiver according to any one of claims 1 to 5 is provided on a suction side of a compressor constituting a refrigerant circuit,
The external input means;
The upstream side is connected to a position having a pressure higher than the internal pressure of the second liquid reservoir container in the refrigerant circuit, and the downstream side is constituted by a refrigerant injection pipe opened to the inside of the second liquid reservoir container. A refrigeration cycle apparatus characterized by comprising: The refrigeration cycle apparatus according to claim 6, wherein a first on-off valve is provided in the refrigerant injection pipe outside the second liquid reservoir. The liquid receiver according to any one of claims 1 to 5 is provided on a suction side of a compressor constituting a refrigerant circuit,
The external input means;
A refrigeration cycle apparatus comprising a heating device for heating the second liquid reservoir. The refrigeration cycle according to any one of claims 6 to 8, wherein a second on-off valve is provided in the first oil return pipe outside the first liquid reservoir and the second liquid reservoir. apparatus. The state of the refrigerating machine oil and the refrigerant staying in the second liquid reservoir is determined by at least one of the refrigerant pressure and temperature on the suction side of the liquid receiver, and the first on-off valve is opened or closed, or the first The refrigeration cycle apparatus according to any one of claims 6 to 9, further comprising: a two-layer separation detection control unit that controls opening and closing of the two on-off valves or energization of the heating device. The two-layer separation detection control means is
When it is determined that there is a refrigeration oil layer above the liquid refrigerant, the first on-off valve is opened, or the second on-off valve is closed, or the heating device is turned on,
If it is determined that the refrigerating machine oil and the refrigerant are in a compatible state or that there is a refrigerating machine oil layer below the liquid refrigerant, the second on-off valve is closed, the first on-off valve is opened, or the heating device is turned off. The refrigeration cycle apparatus according to claim 10. Refrigerating machine oil is used in which the oil density is lower than the refrigerant density when the evaporation temperature is lower than a predetermined value, and the incompatible or weakly compatible oil is used. The refrigeration cycle apparatus according to item. The refrigerant | coolant which becomes a supercritical state in the high voltage | pressure side is used. The refrigeration cycle apparatus as described in any one of Claims 6-12 characterized by the above-mentioned. The refrigeration cycle apparatus according to claim 13, wherein the liquid receiver is an accumulator or a receiver.

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