JP2008190790A - Refrigerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely recover an oil accumulated in a heat exchanger into a compressor. <P>SOLUTION: This refrigerating device has a refrigerant circuit 11 of a steam compression type refrigerating cycle constituted by connecting by refrigerant piping 12 the compressor 13, an outdoor heat exchanger 16, an outdoor expansion valve 21, an indoor expansion valve 22, and an indoor heat exchanger 23. A liquid receiver 27 is disposed in the refrigerant piping 12 between the outdoor heat exchanger 16 and the indoor heat exchanger 23. The refrigerant circuit 11 is provided with a bypass passage 30 connecting the liquid receiver 27 and a suction side of the compressor 13. An oil recovering portion 33 supplies the discharged refrigerant of the compressor 13 to the outdoor heat exchanger 16, and directly returns the refrigerant discharged from the outdoor heat exchanger 16 to the suction side of the compressor 13 through the bypass passage 30 to recover the oil. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a refrigeration apparatus, and particularly relates to measures for collecting oil in a heat exchanger.

Conventionally, as disclosed in Patent Document 1, an air conditioner that is a refrigeration apparatus increases a capacity of a compressor and increases a refrigerant circulation amount in a refrigerant circuit when a predetermined oil recovery condition is reached. The oil collected in is collected. This oil recovery prevents the compressor from seizing.
Japanese Patent Laid-Open No. 6-74580

    However, in the conventional oil recovery operation, the refrigerant discharged from the compressor circulates through the entire refrigerant circuit and returns to the compressor. That is, conventionally, the refrigerant flows, for example, from the compressor through the outdoor heat exchanger, and then flows through the indoor heat exchanger and returns to the compressor. Therefore, the oil accumulated in the outdoor heat exchanger or the indoor heat exchanger is sufficient. There was a problem that could not be recovered.

    In particular, in a refrigeration system using carbon dioxide as a refrigerant, since oil incompatible with carbon dioxide is used, the oil does not dissolve in the liquid refrigerant and remains in the outdoor heat exchanger or the indoor heat exchanger, and is compressed. There was a problem that caused the machine to run out of oil.

    This invention is made | formed in view of such a point, and it aims at collect | recovering the oil collected in the heat exchanger to a compressor reliably.

    In the present invention, the oil in the heat exchanger is recovered by the flow rate of the refrigerant discharged from the compressor.

    The first invention is a vapor compression in which a compressor (13), a heat source side heat exchanger (16), an expansion mechanism (20), and a use side heat exchanger (23) are connected by a refrigerant pipe (12). A refrigerant circuit (11) of the refrigeration cycle, and a refrigerant receiver (27) in the refrigerant pipe (12) between the heat exchanger (16) on the heat source side and the heat exchanger (23) on the user side. The bypass passage (30) connecting the receiver (27) and the suction side of the compressor (13), and the refrigerant discharged from the compressor (13) is supplied to one heat exchanger (16, 23), Oil recovery means (33) for performing an oil recovery operation for directly returning the refrigerant discharged from the heat exchanger (16, 23) to the suction side of the compressor (13) via the bypass passage (30). Yes.

    In the first aspect of the invention, for example, when the accumulated operation time reaches a predetermined time, the oil recovery operation for recovering the oil accumulated in the heat source side or use side heat exchanger (16, 23) is executed. And, for example, when performing oil recovery operation of the heat source side heat exchanger (16), when the compressor (13) is driven, the refrigerant discharged from the compressor (13) is transferred to the heat source side heat exchanger (16). And is discharged from the heat source side heat exchanger (16) together with the oil accumulated in the heat source side heat exchanger (16). Thereafter, the refrigerant from which the oil has been collected flows from the liquid receiver (27) through the bypass passage (30) and directly returns to the compressor (13). By performing this operation for a predetermined time, the oil in the heat exchanger (16) on the heat source side is recovered in the compressor (13).

    In a second aspect based on the first aspect, the expansion mechanism (20) includes a heat source side expansion valve (21) and a use side expansion valve (22), and the bypass passage (30) includes the bypass passage ( On the other hand, the oil recovery means (33) has the use side expansion valve (22) fully closed, and the heat source side expansion valve (21) and the on / off valve (31). The refrigerant discharged from the compressor (13) is supplied to the heat exchanger (16) on the heat source side, and the refrigerating machine oil remaining in the heat exchanger (16) on the heat source side is recovered.

    In the second aspect of the invention, when oil is recovered from the heat source side heat exchanger (16), the heat source side expansion valve (21) and the on-off valve (31) are opened, and the use side expansion valve (22) is fully opened. It is closed and the refrigerant flow to the heat exchanger (23) on the use side is blocked.

    In a third aspect based on the first aspect, the expansion mechanism (20) includes a heat source side expansion valve (21) and a use side expansion valve (22), and the bypass passage (30) includes the bypass passage ( The oil recovery means (33) fully closes the heat source side expansion valve (21) and opens the use side expansion valve (22) and the on-off valve (31). The refrigerant discharged from the compressor (13) is supplied to the use-side heat exchanger (23), and the refrigeration oil remaining in the use-side heat exchanger (23) is recovered.

    In the third aspect of the invention, when oil is recovered from the use side heat exchanger (23), the use side expansion valve (22) and the open / close valve (31) are opened, and the heat source side expansion valve (21) is fully opened. The refrigerant is closed to prevent the refrigerant flow to the heat source side heat exchanger (16).

    In a fourth aspect based on the third aspect, a plurality of use side heat exchangers (23) are connected in parallel to each other, and a use side expansion valve (22) is connected to each use side heat exchanger (23 ), The oil recovery means (33) opens the use side expansion valve (22) corresponding to one use side heat exchanger (23), and the other use side expansion valve (22). Is configured to collect the remaining refrigerating machine oil for each heat exchanger (23) on the use side.

    In the fourth aspect of the invention, oil recovery is performed for each use-side heat exchanger (23). In other words, the refrigerant discharged from the compressor (13) flows directly to one heat exchanger (23) on the user side, and together with the oil accumulated in the heat exchanger (23) on the user side, the heat exchanger (23) on the user side. Discharge from. Thereafter, the refrigerant from which the oil has been collected flows from the liquid receiver (27) through the bypass passage (30) and directly returns to the compressor (13). This operation is performed for a predetermined time and is performed for all the use side heat exchangers (23), whereby oil in the use side heat exchanger (23) is recovered in the compressor (13).

    In a fifth aspect based on the third aspect, the use-side heat exchanger (23) is configured such that a plurality of refrigerant tubes (24) forming a plurality of paths are connected in parallel to each other, and each refrigerant tube On the other hand, an on-off valve (25) is provided corresponding to (24), while the oil recovery means (33) opens an on-off valve (25) corresponding to one refrigerant pipe (24) and another on-off valve (25) Is configured to collect the remaining refrigeration oil for each refrigerant pipe (24).

    In the fifth aspect of the invention, when collecting oil in the heat exchanger (23) on the use side, it is performed for each pass. Specifically, when oil is recovered from the use side heat exchanger (23), the opening / closing valve (25) of this one pass is opened and the other auxiliary opening / closing valve (25) is closed. When the refrigerant is flowed in this state, the oil accumulated in the refrigerant pipe (24) of one pass is recovered.

    In a sixth aspect based on the fourth aspect, the heat exchanger (23) on each use side is configured by connecting a plurality of refrigerant tubes (24) forming a plurality of paths in parallel to each other, On-off valves (25) are provided corresponding to the refrigerant pipes (24), while the oil recovery means (33) is provided with a use side expansion valve (22) corresponding to one use side heat exchanger (23). Open, open the other use-side expansion valve (22), close the open / close valve (25) corresponding to one refrigerant pipe (24), and close the other open / close valve (25) to use one Refrigerating machine oil remaining for each side heat exchanger (23) and for each refrigerant pipe (24) is recovered.

    In the sixth aspect of the invention, the refrigerant is collected for each pass of the heat exchanger (23) on one use side, and then the refrigerant is also collected for each pass on the heat exchanger (23) on the other use side. Recover.

    In a seventh aspect based on the second aspect, the heat exchanger (16) on the heat source side is configured by connecting a plurality of refrigerant pipes (17) forming a plurality of paths in parallel to each other. The on-off valve (18) corresponding to (17) is opened, and the other on-off valve (18) is fully closed to collect the remaining refrigeration oil for each refrigerant pipe (17).

    In the seventh aspect of the invention, when the oil recovery of the heat exchanger (16) on the heat source side is performed, it is performed for each pass. Specifically, when oil is recovered from the heat exchanger (16) on the heat source side, the opening / closing valve (18) of this one pass is opened and the other auxiliary opening / closing valve (18) is closed. When the refrigerant is flowed in this state, the oil accumulated in the refrigerant pipe (17) of one pass is recovered.

    In an eighth aspect based on the first aspect, the oil recovery means (33) is configured to perform an oil recovery operation according to the operating time of the refrigeration cycle.

    In the eighth aspect of the invention, oil recovery is performed on the heat exchangers (16, 23) every predetermined time.

    In a ninth aspect based on the first aspect, the refrigerant circuit (11) performs a supercritical refrigeration cycle using carbon dioxide as a refrigerant, and the compressor (13) is filled with refrigerant oil that is incompatible with the refrigerant. It is comprised so that.

    In the ninth aspect of the invention, the oil incompatible with the refrigerant is reliably recovered in the compressor (13).

    In a tenth aspect based on the first aspect, the refrigerant circuit (11) includes a four-way switching valve (15), and the refrigerant circulation is configured to be reversible.

    In the tenth aspect of the invention, oil recovery is sequentially performed on the heat source side heat exchanger (16) and the use side heat exchanger (23).

    According to the present invention, the bypass passage (30) connecting the liquid receiver (27) and the suction side of the compressor (13) is provided, and the refrigerant discharged from the compressor (13) is supplied to one heat exchanger (16 , 23), and the refrigerant is directly returned from the heat exchanger (16, 23) to the compressor (13), so that the oil in the heat exchanger (16, 23) is transferred to the compressor (13 ) Is discharged from the heat exchanger by the flow rate of the discharged refrigerant, and the oil is recovered to the compressor (13) by the flow rate of the refrigerant as it is, so that the oil accumulated in the heat exchanger (16, 23) of 1 is surely It can be recovered in the compressor (13). As a result, it is possible to reliably prevent the compressor (13) from running out of oil, and thus the reliability of the compressor (13) can be improved.

    According to the second aspect of the invention, when the oil in the heat source side heat exchanger (16) is recovered, the use side expansion valve (22) is fully closed. Since the oil in (16) does not circulate in the heat exchanger (23) on the use side, the oil in the heat exchanger (16) on the heat source side can be reliably recovered in the compressor (13). .

    According to the third aspect of the invention, when the oil in the heat exchanger (23) on the use side is recovered, the expansion valve (21) on the heat source side is fully closed, so the heat exchanger on the use side Since the oil of (23) does not circulate through the heat source side heat exchanger (16), the oil of the use side heat exchanger (23) can be reliably recovered in the compressor (13). .

    Further, according to the fourth aspect of the present invention, oil recovery is performed for each of the usage-side heat exchangers (23) for the plurality of usage-side heat exchangers (23). ) Oil can be reliably recovered in the compressor (13).

    Further, according to the fifth and sixth inventions, since oil is collected for each path of each use-side heat exchanger (23), each refrigerant in each use-side heat exchanger (23) The oil accumulated in the pipe (24) can be reliably recovered. As a result, the oil in the heat exchanger (23) on each use side can be reliably recovered.

    Further, according to the seventh aspect of the invention, since oil recovery is performed for each path of the heat source side heat exchanger (16), each refrigerant pipe (17) of the heat source side heat exchanger (16) Accumulated oil can be reliably collected. As a result, the oil in the heat exchanger (16) on the heat source side can be reliably recovered.

    According to the ninth invention, when oil incompatible with the refrigerant is used as the refrigerating machine oil of the compressor (13), the oil accumulated in the heat exchanger (16, 23) is recovered by the liquid refrigerant. Therefore, the oil in the heat exchanger (16, 23) can be reliably recovered in the compressor (13) by the flow rate of the refrigerant.

    Further, according to the tenth aspect of the invention, since the four-way switching valve (15) is provided, the oil recovery is sequentially performed on the heat source side heat exchanger (16) and the use side heat exchanger (23). It can be performed.

    Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
As shown in FIG. 1, in this embodiment, the refrigeration apparatus of the present invention is applied to an air conditioner (10) that switches between a cooling operation and a heating operation.

    The air conditioner (10) includes a refrigerant compression circuit (11) in which a refrigerant circulates to constitute a vapor compression refrigeration cycle and the refrigerant circulation is reversible.

    The refrigerant circuit (11) includes a compressor (13), an oil separator (14), a four-way switching valve (15), an outdoor heat exchanger (16) that is a heat exchanger on the heat source side, and an expansion An outdoor expansion valve (21) that is a mechanism, a liquid receiver (27), an indoor expansion valve (22) that is an expansion mechanism, and an indoor heat exchanger (23) that is a heat exchanger on the use side are refrigerant piping. (12) are connected in series in order. The refrigerant circuit (11) uses carbon dioxide (CO2) as a refrigerant, and oil that is incompatible with carbon dioxide is used as a refrigerating machine oil for the compressor (13).

    A plurality of indoor heat exchangers (23) (two in FIG. 1) are connected in parallel to each other. And the said indoor expansion valve (22) is provided with two or more (two in FIG. 1) corresponding to each indoor heat exchanger (23).

    One end of an oil return passage (28) is connected to the liquid receiver (27). The other end of the oil return passage (28) is connected to the suction pipe of the compressor (13), and an oil return on-off valve (29) is provided. The end of the oil return passageway (28) on the liquid receiver (27) side is introduced into the liquid receiver (27) from the bottom of the liquid receiver (27). The oil return passage (28) is configured to return the oil accumulated in the liquid receiver (27) to the compressor (13).

    Furthermore, a bypass passage (30) for oil recovery, which is a feature of the present invention, is connected to the liquid receiver (27).

    One end of the bypass passage (30) is connected to the upper part of the liquid receiver (27), and the other end communicates with the suction pipe of the compressor (13). The bypass passage (30) is provided with an oil recovery on-off valve (31).

    Further, the refrigerant circuit (11) is provided with a controller (32) for controlling the compressor (13) and the like. The controller (32) is provided with an oil recovery section (33) as oil recovery means.

    The oil recovery section (33) is a feature of the present invention, and controls the outdoor expansion valve (21), the indoor expansion valve (22), and the on-off valve (31), so that the compressor (13) The discharged refrigerant is supplied to the outdoor heat exchanger (16) or the indoor heat exchanger (23), and the refrigerant discharged from the outdoor heat exchanger (16) or the indoor heat exchanger (23) is supplied to the compressor (13). An oil recovery operation for returning directly to the suction side via the bypass passage (30) is performed.

    Specifically, the oil recovery section (33) opens the outdoor expansion valve (21) and the oil recovery on-off valve (31), closes the indoor expansion valve (22), and discharges refrigerant from the compressor (13). Is returned from the outdoor heat exchanger (16) to the compressor (13) through the liquid receiver (27) and the bypass passage (30). The oil recovery section (33) opens the indoor expansion valve (22) and the oil recovery on-off valve (31), closes the outdoor expansion valve (21), and discharges the refrigerant discharged from the compressor (13) to the room. The heat exchanger (23) returns to the compressor (13) through the liquid receiver (27) and the bypass passage (30).

    The oil recovery section (33) is configured to perform an oil recovery operation corresponding to the operating time of the refrigerant circuit (11) .For example, the oil collected in the outdoor heat exchanger (16) and each indoor heat exchange The oil collected in the vessel (23) is collected every predetermined time. In short, the oil recovery section (33) compresses the oil accumulated in the outdoor heat exchanger (16) and the oil accumulated in each indoor heat exchanger (23) by the flow rate of the refrigerant discharged from the compressor (13). The machine (13) is configured to collect.

-Driving action-
Next, operation | movement of the air conditioning apparatus (10) mentioned above is demonstrated.

    First, during cooling operation, when the four-way switching valve (15) is switched to the solid line side and the compressor (13) is driven, the refrigerant discharged from the compressor (13) is transferred to the outdoor heat exchanger (16). Then, the pressure is reduced by the indoor expansion valve (22) through the liquid receiver (27), and then evaporated by the indoor heat exchanger (23) to return to the compressor (13). This operation is repeated to cool the indoor air in each indoor heat exchanger (23).

    Further, during the heating operation, when the four-way switching valve (15) is switched to the broken line side and the compressor (13) is driven, the refrigerant discharged from the compressor (13) is transferred to each indoor heat exchanger (23 ), The pressure is reduced by the outdoor expansion valve (21) through the liquid receiver (27), and then evaporated by the outdoor heat exchanger (16) to return to the compressor (13). This operation is repeated to heat the indoor air in each indoor heat exchanger (23).

    On the other hand, for example, when the accumulated operation time reaches a predetermined time, the oil recovery unit (33) performs an oil recovery operation for recovering oil accumulated in the outdoor heat exchanger (16) and the indoor heat exchanger (23).

    Then, the oil recovery of the outdoor heat exchanger (16) will be described. The outdoor expansion valve (21) and the oil recovery on-off valve (31) are opened, the indoor expansion valve (22) is fully closed, and the four-way switching is performed. Switch the valve (15) to the solid line state. In this state, when the compressor (13) is driven, the refrigerant discharged from the compressor (13) (see the point in FIG. 2a) flows directly to the outdoor heat exchanger (16) and accumulates in the outdoor heat exchanger (16). It is discharged from the outdoor heat exchanger (16) together with the oil (see point in FIG. 2b). After that, the refrigerant from which the oil has been recovered is decompressed by the outdoor expansion valve (21) (see FIG. 2c), and then flows from the liquid receiver (27) through the bypass passage (30) to the compressor (13) directly. It will return (see FIG. 2d point). By performing this operation for a predetermined time, the oil in the outdoor heat exchanger (16) is recovered in the compressor (13).

    The oil recovery of the indoor heat exchanger (23) will be described. The indoor expansion valve (22) and the oil recovery on-off valve (31) are opened, the outdoor expansion valve (21) is fully closed, and the four-way switching is performed. Switch valve (15) to broken line. In this state, oil recovery is performed for each indoor heat exchanger (23). That is, only one indoor expansion valve (22) is opened, and the other indoor expansion valves (22) are fully closed. When the compressor (13) is driven from this state, the refrigerant discharged from the compressor (13) flows directly into the indoor heat exchanger (23), and the indoor heat exchange together with the oil accumulated in the indoor heat exchanger (23). Is discharged from the container (23). Thereafter, the refrigerant from which the oil has been recovered is decompressed by the indoor expansion valve (22), then flows from the liquid receiver (27) through the bypass passage (30), and directly returns to the compressor (13). By performing this operation for a predetermined time and for all the indoor heat exchangers (23), the oil in the indoor heat exchanger (23) is recovered in the compressor (13).

    When oil is accumulated in the receiver (27) over a predetermined amount, the oil return on-off valve (29) is opened, and the oil in the receiver (27) is discharged from the oil return passage (28) to the compressor. Return to (13).

-Effect of Embodiment 1-
As described above, according to the present embodiment, the bypass passage (30) that connects the liquid receiver (27) and the suction side of the compressor (13) is provided, and the refrigerant discharged from the compressor (13) is used as outdoor heat. The refrigerant (16) or the indoor heat exchanger (23) is supplied, and the refrigerant is directly returned to the compressor (13) from the outdoor heat exchanger (16) or the indoor heat exchanger (23). Oil in the outdoor heat exchanger (16) or the indoor heat exchanger (23) is discharged from the outdoor heat exchanger (16) or the indoor heat exchanger (23) according to the flow rate of the refrigerant discharged from the compressor (13), Since the oil is recovered to the compressor (13) by the flow rate of the refrigerant as it is, the oil accumulated in the outdoor heat exchanger (16) or the indoor heat exchanger (23) must be reliably recovered to the compressor (13). Can do. As a result, it is possible to reliably prevent the compressor (13) from running out of oil, and thus the reliability of the compressor (13) can be improved.

    In particular, when oil that is incompatible with the refrigerant is used as the refrigeration oil for the compressor (13), the oil accumulated in the outdoor heat exchanger (16) or the indoor heat exchanger (23) should be recovered with the liquid refrigerant. Therefore, the oil in the outdoor heat exchanger (16) or the indoor heat exchanger (23) can be reliably recovered in the compressor (13) by the flow rate of the refrigerant.

    Further, when the oil in the outdoor heat exchanger (16) is recovered, the indoor expansion valve (22) is fully closed, so that the oil in the outdoor heat exchanger (16) passes through the indoor heat exchanger (23). Since it does not circulate, the oil in the outdoor heat exchanger (16) can be reliably recovered in the compressor (13).

    Further, when the oil in the indoor heat exchanger (23) is recovered, the outdoor expansion valve (21) is fully closed, so that the oil in the indoor heat exchanger (23) passes through the outdoor heat exchanger (16). Since it does not circulate, the oil in the indoor heat exchanger (23) can be reliably recovered in the compressor (13).

    Also, since oil is collected for each indoor heat exchanger (23) for a plurality of indoor heat exchangers (23), the oil in each indoor heat exchanger (23) must be reliably collected in the compressor (13). Can do.

    In addition, since the four-way switching valve (15) is provided, oil recovery can be sequentially performed on the outdoor heat exchanger (16) and the indoor heat exchanger (23).

<Embodiment 2>
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

    In the present embodiment, instead of the first embodiment performing one oil recovery for one indoor heat exchanger (23), the oil is recovered for each pass of the indoor heat exchanger (23). It is a thing.

    That is, in this embodiment, as shown in FIG. 3, each indoor heat exchanger (23) is configured by a path including a plurality of refrigerant tubes (24). Then, both ends of each refrigerant pipe (24) are connected to a header (26) and connected in parallel to each other, and the header (26) is configured to perform refrigerant diversion and collection.

    Furthermore, an auxiliary on-off valve (25) for oil recovery is provided at one end of each refrigerant pipe (24). The auxiliary on-off valve (25) is provided on the side where the refrigerant flows into each refrigerant pipe (24) during the heating operation.

    Therefore, the oil recovery means (33) is performed for each pass when recovering the oil in one indoor heat exchanger (23). Specifically, when oil is recovered from one indoor heat exchanger (23), one auxiliary on-off valve (25) in this one indoor heat exchanger (23) is opened and the other auxiliary on-off valve (25) is opened. Is in a closed state.

    When the compressor (13) is operated from this state, the refrigerant discharged from the compressor (13) flows directly into one refrigerant pipe (24) of the indoor heat exchanger (23) and accumulates in the refrigerant pipe (24). It is discharged from the indoor heat exchanger (23) together with the oil. Thereafter, the refrigerant from which the oil has been collected flows from the liquid receiver (27) through the bypass passage (30) and directly returns to the compressor (13). Subsequently, another auxiliary opening / closing valve (25) is opened and the other auxiliary opening / closing valve (25) is closed, and the above-described operation is repeated. By collecting the oil in all the refrigerant pipes (24), the oil in one indoor heat exchanger (23) is collected in the compressor (13). By performing this operation for all the indoor heat exchangers (23), the oil in the indoor heat exchanger (23) is recovered in the compressor (13). Other configurations and operations are the same as those of the first embodiment.

-Effect of Embodiment 2-
As described above, according to the present embodiment, since oil recovery is performed for each path of each indoor heat exchanger (23), each refrigerant pipe (24) of each indoor heat exchanger (23) is provided. Accumulated oil can be reliably collected. As a result, the oil in each indoor heat exchanger (23) can be reliably recovered. Other effects are the same as those of the first embodiment.

<Third embodiment of the invention>
Next, a third embodiment of the present invention will be described in detail with reference to the drawings.

    In this embodiment, instead of the first embodiment in which the oil recovery is performed once for the outdoor heat exchanger (16), the oil is recovered for each pass of the outdoor heat exchanger (16). Is.

    That is, in this embodiment, as shown in FIG. 4, the outdoor heat exchanger (16) is configured by a path including a plurality of refrigerant tubes (17). Then, both ends of each refrigerant pipe (17) are connected to a header (19) and connected in parallel to each other, and the header (19) is configured to perform refrigerant diversion and aggregation.

    Furthermore, an auxiliary on-off valve (18) for oil recovery is provided at one end of each refrigerant pipe (17). The auxiliary on-off valve (18) is provided on the side where the refrigerant flows into each refrigerant pipe (17) during the cooling operation.

    Accordingly, the oil recovery means (33) is performed for each pass when recovering the oil in the outdoor heat exchanger (16). Specifically, when oil is recovered from the outdoor heat exchanger (16), one auxiliary on-off valve (18) is opened and the other auxiliary on-off valve (18) is closed.

    When the compressor (13) is operated from this state, the refrigerant discharged from the compressor (13) flows directly into one refrigerant pipe (17) of the outdoor heat exchanger (16) and accumulates in the refrigerant pipe (17). It is discharged from the outdoor heat exchanger (16) together with the oil. Thereafter, the refrigerant from which the oil has been collected flows from the liquid receiver (27) through the bypass passage (30) and directly returns to the compressor (13). Subsequently, the other auxiliary on-off valve (18) is opened, the other auxiliary on-off valve (18) is closed, and the above operation is repeated. By collecting the oil in all the refrigerant pipes (17), the oil in the outdoor heat exchanger (16) is collected in the compressor (13). Other configurations and operations are the same as those of the first embodiment.

-Effect of Embodiment 3-
As described above, according to the present embodiment, since oil recovery is performed for each path of the outdoor heat exchanger (16), the oil is accumulated in each refrigerant pipe (17) of the outdoor heat exchanger (16). Oil can be reliably recovered. As a result, the oil in the outdoor heat exchanger (16) can be reliably recovered. Other effects are the same as those of the first embodiment.

<Other embodiments>
The present invention may be configured as follows with respect to the first embodiment.

    Although each embodiment described the air conditioner, the present invention can be applied to various refrigeration apparatuses such as a refrigerator in addition to the air conditioner.

    In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

    As described above, the present invention is useful for a refrigeration apparatus that recovers oil from a heat exchanger.

FIG. 1 is a refrigerant circuit diagram illustrating an air conditioner according to Embodiment 1 of the present invention. FIG. 2 is a Ph diagram illustrating the refrigerant state during the oil recovery operation according to the first embodiment of the present invention. FIG. 3 is a schematic configuration diagram illustrating the indoor heat exchanger according to the second embodiment. FIG. 4 is a schematic configuration diagram illustrating an outdoor heat exchanger according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Air conditioning apparatus 11 Refrigerant circuit 12 Refrigerant piping 13 Compressor 14 Oil separator 15 Four-way switching valve 16 Outdoor heat exchanger 17 Refrigerant pipe 18 Auxiliary on-off valve 19 Header 20 Expansion mechanism 21 Outdoor expansion valve 22 Indoor expansion valve 23 Indoor heat Exchanger 24 Refrigerant pipe 25 Auxiliary on-off valve 26 Header 27 Receiver 28 Oil return passage 29 Oil return on-off valve 30 Bypass passage 31 Oil recovery on-off valve 32 Controller 33 Oil recovery section

Claims (10)

The refrigerant circuit of the vapor compression refrigeration cycle in which the compressor (13), the heat source side heat exchanger (16), the expansion mechanism (20), and the use side heat exchanger (23) are connected by the refrigerant pipe (12). (11), and the refrigerant pipe (12) between the heat source side heat exchanger (16) and the use side heat exchanger (23) is provided with a liquid receiver (27). And
A bypass passage (30) provided in the refrigerant circuit (11) and connecting the liquid receiver (27) and the suction side of the compressor (13);
The refrigerant discharged from the compressor (13) is supplied to one heat exchanger (16, 23), and the refrigerant discharged from the heat exchanger (16, 23) is bypassed to the suction side of the compressor (13). A refrigeration apparatus comprising an oil recovery means (33) for performing an oil recovery operation for direct return through the passage (30). In claim 1,
The expansion mechanism (20) includes a heat source side expansion valve (21) and a use side expansion valve (22),
The bypass passage (30) includes an on-off valve (31) for opening and closing the bypass passage (30),
The oil recovery means (33) fully closes the use side expansion valve (22), opens the heat source side expansion valve (21) and the on-off valve (31), and discharges the refrigerant discharged from the compressor (13) to the heat source side. The refrigeration apparatus is configured to be supplied to the heat exchanger (16) and to recover the refrigeration oil of the heat exchanger (16) on the heat source side. In claim 1,
The expansion mechanism (20) includes a heat source side expansion valve (21) and a use side expansion valve (22),
The bypass passage (30) includes an on-off valve (31) for opening and closing the bypass passage (30),
The oil recovery means (33) fully closes the heat source side expansion valve (21), opens the use side expansion valve (22) and the on-off valve (31), and uses the refrigerant discharged from the compressor (13) on the use side. The refrigeration apparatus is configured to be supplied to the heat exchanger (23) and collect the refrigeration oil of the heat exchanger (23) on the use side. In claim 3,
The use side heat exchanger (23) is connected in parallel with each other,
While the use side expansion valve (22) is provided corresponding to each use side heat exchanger (23),
The oil recovery means (33) opens one use side expansion valve (22) corresponding to one use side heat exchanger (23) and fully closes the other use side expansion valve (22). A refrigeration apparatus configured to collect refrigeration oil for each side heat exchanger (23). In claim 3,
The use-side heat exchanger (23) is configured by connecting a plurality of refrigerant pipes (24) forming a plurality of paths in parallel to each other,
While an on-off valve (25) is provided corresponding to each refrigerant pipe (24),
The oil recovery means (33) opens the on-off valve (25) corresponding to one refrigerant pipe (24) and fully closes the other on-off valve (25) to supply the refrigerating machine oil to each refrigerant pipe (24). A refrigeration apparatus configured to collect. In claim 4,
Each of the use-side heat exchangers (23) is configured by connecting a plurality of refrigerant tubes (24) forming a plurality of paths in parallel with each other,
While an on-off valve (25) is provided corresponding to each refrigerant pipe (24),
The oil recovery means (33) opens the utilization side expansion valve (22) corresponding to one utilization side heat exchanger (23), fully closes the other utilization side expansion valve (22), and Open the on-off valve (25) corresponding to the refrigerant pipe (24) and fully close the other on-off valve (25) for each heat exchanger (23) on the user side and for each refrigerant pipe (24). The refrigeration apparatus is configured to collect the refrigerating machine oil. In claim 2,
The heat source side heat exchanger (16) is configured by connecting a plurality of refrigerant tubes (17) forming a plurality of paths in parallel with each other,
On-off valves (18) are provided corresponding to the refrigerant pipes (17),
The oil recovery means (33) opens the on-off valve (18) corresponding to one refrigerant pipe (17) and fully closes the other on-off valve (18) to supply the refrigerating machine oil to each refrigerant pipe (17). A refrigeration apparatus configured to collect. In claim 1,
The refrigeration apparatus characterized in that the oil recovery means (33) is configured to perform an oil recovery operation corresponding to the operating time of the refrigerant circuit (11). In claim 1,
The refrigerant circuit (11) performs a supercritical refrigerant cycle using carbon dioxide as a refrigerant, and the compressor (13) is filled with refrigerant oil that is incompatible with the refrigerant. In claim 1,
The refrigerant circuit (11) includes a four-way switching valve (15), and refrigerant circulation is configured to be reversible.

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