JP2010127543A - Refrigerating cycle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively carry out the oil equalization of each compressor by smoothly moving excessive oil in a refrigerating cycle device with a plurality of the low pressure shell compressors arranged in parallel with each other between a high pressure line and a low pressure line. <P>SOLUTION: The refrigerating cycle device is provided with first connection pipes L1(1), L1(2) connecting an oil inlet 2a formed in an oil tank 2 to excessive oil outlets 1c formed in the compressors 1(1), 1(2), first opening and closing valves V1(1), V1(2) formed at the first connection pipes L1(1), L1(2), a second connection pipe L2 connecting the oil inlet 2a to the low pressure line L<SB>1</SB>, a second opening and closing valve V2 provided on the second connection pipe L2, and a control means 4 for opening the second opening and closing valve V2 to make the oil inlet 2a communicate with the low pressure line L<SB>1</SB>during a predetermined oil tank introducing mode, and opening the first opening and closing valves V1(1), V1(2) to make the excessive oil outlets 1c communicate with the oil inlet 2a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus in which a plurality of low-pressure shell compressors are connected in parallel between a high-pressure line and a low-pressure line, and more particularly to a mechanism that evenly distributes lubricating oil of each compressor.

In a refrigeration cycle apparatus in which a plurality of high-pressure shell compressors are connected in parallel between a high-pressure line (hereinafter also referred to as a discharge pipe) and a low-pressure line (hereinafter also referred to as a suction pipe), as shown in Patent Document 1, In order to equalize the machine, the oil tank is connected to the high-pressure line and the low-pressure line via a throttle mechanism, and the shell of each compressor is connected to the oil tank. I try to keep it.
Compressor shell pressure> oil tank pressure> low pressure line pressure

  Due to this pressure difference, the excess oil of each compressor naturally moves to the oil tank and is distributed to each compressor from the low pressure line.

When oil is moved to another outdoor unit, high-pressure gas is allowed to flow through the oil tank, and oil is moved to the other outdoor unit via a separately provided balance pipe.
JP 2004-85088 A

  However, the oil leveling operation described above is carried out only because the compressor shell is at a high pressure. When this configuration is applied to a low-pressure shell compressor, the oil tank pressure may be higher than the shell pressure. Therefore, wrinkles occur in the oil movement, and the certainty and reliability of the oil leveling operation are lacking.

  The present invention has been made in view of such problems, and the main problem is that in a refrigeration cycle apparatus configured using a low-pressure shell compressor, the excess oil can be smoothly removed while having a simple configuration. An object of the present invention is to provide a compressor that can be moved to ensure oil leveling of each compressor.

  That is, the refrigeration cycle apparatus according to the present invention is a refrigeration cycle apparatus in which a plurality of low-pressure shell compressors are arranged in parallel between a high-pressure line and a low-pressure line, and is an upper side above a lower space in which oil is stored. An oil tank having an oil inlet opening in the space; a first connection pipe connecting the oil inlet provided in the oil tank to a surplus oil outlet provided in each compressor; and the first connection pipe A first on-off valve provided above, a second connection pipe connecting the oil inlet to the low-pressure line, a second on-off valve provided on the second connection pipe, and a predetermined oil tank introduction In the mode, the second on-off valve is opened to connect the oil inlet and the low-pressure line, while the first on-off valve is opened to connect the excess oil outlet of each compressor to the oil inlet. Characterized in that it comprises a control means for pass.

  In such a case, since the low pressure line communicates with the upper space of the oil tank by opening the second on-off valve, and the low pressure line is kept at the minimum pressure by the suction action of the compressor, the oil tank The internal pressure is also kept at the minimum pressure. In this state, when the first on-off valve is opened and the surplus oil outlet of each compressor communicates with the oil inlet of the oil tank, surplus oil from each compressor is reliably introduced into the oil tank maintained at the minimum pressure. Will be.

  When at least one of the compressors is a variable capacity compressor having a loading / unloading switching function, the variable capacity compressor is in an unloading state in the oil tank introduction mode. Sometimes, the control means opens the first on-off valve corresponding to the variable capacity compressor so that the excess oil outlet of the variable capacity compressor communicates with the oil inlet of the oil tank. That's fine.

  This is because in the unloading state, the pressure in the shell of the variable capacity compressor increases, and a relatively large pressure difference is generated between the oil tank and the excess oil in the variable capacity compressor. This is because the oil tank can be introduced in time.

  Further, when the compressor includes a fixed displacement compressor, the control means opens the first on-off valve corresponding to the fixed displacement compressor in the oil tank introduction mode, and After the surplus oil outlet of the capacity type compressor communicates with the oil inlet of the oil tank, the first on-off valve is closed, and then the first on-off valve corresponding to the variable capacity compressor is opened. Thus, it is preferable that the surplus oil outlet of the variable capacity compressor communicates with the oil inlet of the oil tank.

  This is because, for example, if the first on-off valve on the variable capacity compressor side is opened first, and then the first on-off valve on the fixed capacity compressor side is opened, excess oil from the variable capacity compressor When the oil is introduced, the empty volume in the oil tank becomes small, and even if the first on-off valve on the fixed capacity compressor side is opened thereafter, the excess oil cannot be smoothly introduced into the oil tank. Because fear arises. This is because when the variable capacity compressor enters the unloading state, the pressure in the shell of the fixed capacity compressor rises along the suction pipe, but does not rise as much as the variable capacity compressor due to the pressure loss of the suction pipe. It is. In other words, the differential pressure between the shell internal pressure and the oil tank pressure of the fixed capacity compressor is small, and the oil tank has a small free space and the pressure rises easily, so that excess oil can be introduced smoothly into the oil tank. Disappear. Further, if the first on-off valves are simultaneously opened, the amount of surplus oil introduced may be biased due to the difference in the pressure in the shell of each compressor.

  In order to distribute the surplus oil introduced into the oil tank as described above to each compressor and to equalize the oil, a third connection pipe that connects a refrigerant discharge port of the compressor to the oil introduction port, A third on-off valve provided on the third connection pipe, a fourth connection pipe for connecting an oil outlet opening in a lower space of the oil tank to the low-pressure line, and provided on the fourth connection pipe. In the predetermined surplus oil local distribution mode, the control means closes the first on-off valve and the second on-off valve, opens the third on-off valve, and It is desirable that the refrigerant discharge port communicate with the oil introduction port of the oil tank and that the oil discharge port of the oil tank communicate with the low pressure line via the throttle mechanism.

  In addition, in order to distribute excess oil introduced into the oil tank to other units such as an outdoor unit and to equalize the entire apparatus including the other units, the fourth connecting pipe is connected in series with the throttle mechanism. A fourth on-off valve provided on the oil tank, a fifth connection pipe branched from the fourth connection pipe closer to the oil tank than the fourth on-off valve and connected to the high-pressure line, and provided on the fifth connection pipe And a check valve that prohibits the flow from the high pressure line, and the control means closes the first, second, and fourth on-off valves in a predetermined excess oil total distribution mode, 3. An on-off valve is opened, the refrigerant discharge port of the compressor is communicated with an oil introduction port of an oil tank, and the oil discharge port of the oil tank is communicated with a high pressure line via a check valve. Is preferred.

  If it is such, since surplus oil is distributed to other units via a high-pressure line, realization with a simple configuration is possible without using a dedicated oil equalizing pipe or the like.

  According to the present invention configured as described above, even when a low-pressure shell compressor is used, oil leveling between the compressors can be achieved, and reliability can be ensured.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a fluid circuit diagram showing an outdoor unit U of an air-conditioning apparatus 100 that is a refrigeration cycle apparatus according to this embodiment.
Note that illustration of heat exchangers, expansion devices, fans, etc. not related to the oil leveling operation is omitted.

In FIG. 1, reference symbol L _h is a high-pressure line, reference symbol is a low-pressure line L _l , and reference symbols 1 (1) and 1 (2) are a plurality (in parallel arranged between the high-pressure line L _h and the low-pressure line L _l. 2) low-pressure shell compressor.
Each of the compressor 1 (1), first refrigerant discharge port 1a of (2), after being connected to one of the high-pressure communication pipe L6, oil separator 3, connected to a high voltage line L _h through a check valve CV3 Has been. Moreover, the compressors 1 (1), the refrigerant suction port 1b of the 1 (2) is connected directly to the low voltage line _{L l.} These compressors 1 (1) and 1 (2) are further provided with a surplus oil outlet 1c. When the oil height in the shell exceeds a certain level, surplus oil is discharged from the surplus oil outlet 1c. It is configured to be.

  The low-pressure shell compressor has a structure in which the inside of a shell storing lubricating oil (hereinafter also simply referred to as oil) is basically maintained near the pressure at the refrigerant inlet of the compressor. Say things.

  There are two types of low-pressure shell compressors 1 (1) and 1 (2) used in this embodiment, as is apparent from the fact that the reference numerals are parenthesized, and one of them is: The fixed capacity type compressor 1 (2) is the variable capacity type compressor 1 (1) having a loading / unloading switching function. This type of variable capacity compressor 1 (1) is provided with a valve mechanism (not shown) for opening the refrigerant suction side and the refrigerant discharge side in the internal pressure-raising structure, and the valve mechanism is closed. In the loaded state, that is, in the loading state, a normal compression operation is performed. On the other hand, in a state where the valve mechanism is opened, that is, in an unloading state, a so-called idle state in which the refrigerant suction side and the refrigerant discharge side are opened is configured so that the compression operation is not sufficiently performed.

  Reference numeral is an oil tank 2 for storing lubricating oil. In the oil tank 2, oil is stored in a lower space inside the oil tank 2, and gas or the like is filled in the upper space. Thus, an oil inlet 2a for introducing oil is opened in the upper space, and an oil outlet 2b for discharging oil is opened in the lower space. In FIG. 1, three oil inlets 2 a are provided. However, an aspect in which three oil inlets are branched from one oil inlet is equal in terms of the fluid circuit, of course.

  Reference numerals L1 (1) and L1 (2) denote first connecting pipes L1 that connect the oil inlet 2a of the oil tank 2 and the surplus oil outlet 1c of the compressors 1 (1) and 1 (2), respectively. (1), L1 (2). A plurality of (two) first connection pipes L1 (1) and L1 (2) corresponding to the number of compressors 1 (1) and 1 (2) can be opened and closed by remote control. Electromagnetic first on-off valves V1 (1) and V1 (2) are provided, respectively, and the excess oil outlet 1c of each compressor 1 (1) and 1 (2) is independently connected to the oil in the oil tank 2. It is comprised so that it can be connected with the inlet 2a.

Reference numeral L2 is a second connection pipe that connects the oil inlet 2a of the oil tank 2 and the vicinity of the refrigerant inlet 1b of the variable capacity compressor 1 (1) in the low-pressure line _Ll . On this second connection pipe L2 is capable of opening and closing by a remote control, for example, a second on-off valve V2 of the electromagnetic, and the check valve CV2 to prohibit flow from the low pressure line L _l is provided in series is there.

  Symbol L3 is a third connection pipe that connects the refrigerant discharge port 1a of each compressor 1 (1), 1 (2) to the oil introduction port 2a. The third connection pipe L3 extending from each refrigerant discharge port 1a is combined into one and connected to the oil introduction port 2a, and a third opening / closing valve V3 is provided in the portion combined into one. The refrigerant discharge ports 1 a of the compressors 1 (1) and 1 (2) can be collectively communicated with the oil introduction port 2 a of the oil tank 2. The third on-off valve V3 is, for example, an electromagnetic type that can be opened and closed by remote control.

Reference numeral L4 is the fourth connection pipe connecting the oil discharge port 2b of the oil tank 2 to the low voltage line L _l. On the fourth connection pipe L4, a throttling mechanism R1 such as a capillary tube serving as a resistor and a fourth open / close valve V4 are provided in series. The fourth on-off valve V4 is, for example, an electromagnetic type that can be opened and closed by remote control, like the first on-off valve V1 to the third on-off valve V3. Although provided in the low voltage line L _l side of the mechanism the stop R1 and the fourth on-off valve V4 in this embodiment, it may be reversed arrangement.

Reference numeral L5 is connected the fourth oil tank 2 side of the fourth on-off valve V4 in the connection pipe L4 branched from (more specifically, the oil tank 2 side of the throttle mechanism R1) to the high pressure line L _h The fifth connection pipe. On this fifth connection pipe L5 is a check valve CV1 to prohibit flow from said high pressure line L _h is provided.

Further, in this embodiment, there is provided control means 4 for controlling the operation and stop of each of the on-off valves V1 to V4 and the compressors 1 (1) and 1 (2) or switching between loading / unloading by an electric signal. Yes.
The control means 4 is a so-called computer having a CPU, a memory, an I / O channel, an AD converter, and the like, and the above-described on-off valve V1 is operated by the CPU and its peripheral devices operating according to the program stored in the memory. Control V4 and compressors 1 (1) and 1 (2).

  Next, the operation of the air-conditioning apparatus 100 according to the present embodiment will be described in detail below while also serving as an explanation of the control method by the control means 4.

<Oil tank introduction mode>
In this mode, the operation of introducing excess oil from the compressors 1 (1) and 1 (2) into the oil tank 2 is performed. Note that this mode is not performed simultaneously with the surplus oil distribution mode and the surplus oil total distribution mode, which will be described later, and the modes are mutually exclusive.

  First, as a premise, the control means 4 issues a command signal to the variable capacity compressor 1 (1), and periodically switches between a loading state and an unloading state. Further, the ratio between the loading time and the unloading time at that time is fixed so as to be constant (step S11 in FIG. 2).

Next, as shown in FIG. 4 and FIG. 2, step S12, the control means 4 opens the second on-off valve V2 in the loading state, and the upper space of the oil tank 2 and the low pressure line L ₁ (capacity variable compressor). 1 (1) and 1 (2) in the vicinity of the refrigerant suction port 1b) through the second connection pipe L2. At this time, all the other on-off valves V1, V3, V4 are closed. Thus, although the internal pressure of the oil tank 2 matches the pressure of the low pressure line L _l, the loading state, variable capacity type compressor 1 (1), since the suction pressure of 1 (2) becomes minimum, The pressure in the low pressure line L ₁ is the lowest, and therefore the internal pressure of the oil tank 2 is also the lowest.

On the other hand, the control means 4 opens the first on-off valves V1 (1) and V1 (2), and the excess oil outlet 1c of each compressor 1 (1) and 1 (2) is connected to the oil in the oil tank 2. Although it communicates with the inlet 2a, the details of the control are as follows.
That is, the control means 4 opens the second on-off valve V2, and then opens the first on-off valve V1 (2) communicating with the fixed displacement compressor 1 (2) for a certain period of time. 1 (2) surplus oil is introduced into the oil tank 2. At this time, since the internal pressure of the oil tank 2 is kept at a minimum, the surplus oil moves smoothly even if the fixed displacement compressor 1 (2) is stopped. Further, when the variable capacity compressor 1 (1) is in the unloading state, the pressure in the shell of the constant capacity compressor 1 (2) also increases, so that the surplus oil moves more smoothly.

  Next, as shown in step S13 of FIG. 5 and FIG. 2, the control means 4 closes the first on-off valve V1 (2) and communicates with the variable capacity compressor 1 (1). ) Is opened for a certain period of time, and surplus oil from the variable capacity compressor 1 (1) is introduced into the oil tank 2. When this operation is performed in the unloading state, the pressure in the shell of the variable capacity compressor 1 (1) increases, and a relatively large pressure difference is generated between the oil tank 2 and the variable capacity type. The surplus oil of the compressor 1 (1) is also introduced into the oil tank 2 smoothly and in a short time. At this time, the second on-off valve V2 may be closed.

  By the way, contrary to the procedure described above, the first on-off valve V1 (1) on the variable capacity compressor 1 (1) side is opened first, and then the first on-off valve on the fixed capacity compressor 1 (2) side is opened. When the valve V1 (2) is opened, the free volume in the oil tank becomes small when surplus oil from the variable capacity compressor 1 (1) is introduced. Then, the pressure difference between the shell internal pressure of the fixed capacity compressor 1 (2) and the oil tank 2 internal pressure is smaller than the pressure difference between the variable capacity compressor 1 (1) and the oil tank 2 internal pressure. In addition, since the oil tank 2 has a small free volume and pressure tends to increase, there is a risk that the excess oil of the fixed capacity compressor 1 (2) cannot be smoothly introduced into the oil tank 2. Therefore, it is not preferable to change the opening / closing order of the first opening / closing valves V1 (1) and V1 (2). It is also conceivable to open the first on-off valves V1 (1) and V1 (2) at the same time. However, due to the difference in pressure in the shells of the compressors 1 (1) and 1 (2), introduction of excess oil There is a possibility that the amount may be biased, which is not preferable.

  In the experiment in which the inventor performed a constant amount of oil movement with a loading / unloading period of 20 seconds, it was found that the oil movement time could be shortened most when the loading time was 7 seconds to 9 seconds (per experimental data). FIG. 8).

  Accordingly, if the loading time is set to an appropriate value, the pressure difference between the compressors 1 (1), 1 (2) shell and the oil tank 2 can be increased, and the volume of the oil tank 2 can be reduced accordingly. . Therefore, the cost of the oil tank 2 can be reduced.

<Excess oil local distribution mode>
In this mode, the operation of distributing the excess oil stored in the oil tank 2 to the compressors 1 (1) and 1 (2) of the outdoor unit U is performed.

More specifically, the control means 4 closes the first on-off valves V1 (1), V1 (2) and the second on-off valve V2 as shown in FIG. The on-off valve V3 and the fourth on-off valve V4 are opened. That is, the refrigerant discharge ports 1a of the compressors 1 (1) and 1 (2) are communicated with the oil introduction port 2a of the oil tank 2, and the oil discharge port 2b of the oil tank 2 is connected to the fourth connection pipe L4. communicating the low pressure line L _l via a throttle mechanism R1.

As a result, the internal pressure of the oil tank 2 rises to the refrigerant discharge pressure of the compressors 1 (1), 1 (2), and excess oil stored in the oil tank 2 flows from the oil discharge port 2b to the low pressure line L. ₁ is distributed to the refrigerant inlets 1b of the compressors 1 (1) and 1 (2).
Therefore, oil leveling between the compressors 1 (1) and 1 (2) can be achieved, and reliability can be ensured. In addition, since the throttle mechanism R1 is provided on the fourth connection pipe L4, the amount of refrigerant that bypasses from high pressure to low pressure is small, and the performance degradation is small.

  Note that this mode may be performed in either an unloading state or a loading state. However, it is preferable to perform this mode in the loading state in order to increase the oil discharge speed by introducing a higher pressure by the oil tank 2.

  Thus, after performing the oil leveling operation in the outdoor unit U, the operation returns to the normal operation (step S15 in FIG. 2).

<Overall oil distribution mode>
In this mode, an operation of distributing surplus oil stored in the oil tank 2 to the other outdoor units U is performed.
More specifically, the control means 4 performs the above-described oil tank introduction mode (shown in steps S21 to S23 in FIG. 3 and the same as steps S11 to S13 in FIG. 2).
Next, as shown in FIG. 7 and FIG. 3 step S24, only the third on-off valve V3 is opened, and the refrigerant discharge port 1a of the compressors 1 (1) and 1 (2) is connected to the oil introduction port of the oil tank 2. with communicating to 2a, to communicate with the high pressure line L _h through the check valve of the oil discharge port 2b of the oil tank 2.

As a result, the internal pressure of the oil tank 2 rises to the refrigerant discharge pressure of the compressors 1 (1) and 1 (2), and excess oil stored in the oil tank 2 is connected to the fifth connection from the oil discharge port 2b. pipe L5, through a high pressure line L _h is discharged into the other outdoor unit U.
This operation is periodically performed for each outdoor unit U. As a result, oil leveling between the outdoor units U can be achieved and reliability can be ensured.

  As described above, according to the air conditioner 100 according to the present embodiment, even when the low-pressure shell compressors 1 (1), 1 (2) are used, the compressor 1 (1) in the outdoor unit U, Oil leveling can be achieved between 1 (2) and between the outdoor units U, and reliability can be ensured. In addition, surplus oil can be recovered from the stopped compressor, which also contributes to ensuring reliability. Furthermore, since an oil equalizing pipe between the outdoor units U is not required, the structure can be simplified and the workability associated therewith can be improved.

The present invention is not limited to the above embodiment.
For example, the present invention can be applied to an air conditioner that is composed entirely of a fixed-capacity low-pressure shell compressor. In this case, in the oil tank introduction mode, it is not possible to reduce the oil movement time by pumping oil to the oil tank in the unloading state as in the case where the variable capacity compressor exists, but at least the oil tank is Since the minimum pressure can be achieved, excess oil from each compressor can be reliably discharged to the oil tank.

Moreover, although the said embodiment demonstrated the air conditioning apparatus which has multiple outdoor units, a single outdoor unit may be sufficient. In that case, the surplus oil whole distribution mode may be deleted.
Furthermore, the number of low-pressure shell compressors is not limited to the above-described embodiment, and may be a larger number, and is not limited to an air conditioner, and can be applied to other refrigeration cycle equipment.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

The fluid circuit diagram which shows the air conditioning apparatus in one Embodiment of this invention. The flowchart which shows operation | movement of the air conditioning apparatus in the embodiment. The flowchart which shows operation | movement of the air conditioning apparatus in the embodiment. The fluid circuit diagram which shows operation | movement of the air conditioning apparatus in the embodiment. The fluid circuit diagram which shows operation | movement of the air conditioning apparatus in the embodiment. The fluid circuit diagram which shows operation | movement of the air conditioning apparatus in the embodiment. The fluid circuit diagram which shows operation | movement of the air conditioning apparatus in the embodiment. The graph which shows the experimental result in the same embodiment.

Explanation of symbols

100: Refrigeration cycle device (air conditioner)
DESCRIPTION OF SYMBOLS 1 (1) ... Variable capacity type compressor 1 (2) ... Fixed capacity type compressor 1a ... Refrigerant discharge port 1c ... Excess oil outlet 2 ... Oil tank 2a ... Oil inlet 2b ... oil discharge port 4 ... control unit _L l ... low voltage line _L h ... high voltage line L1 (1), L1 (2 ) ··· first connection piping L2 ... first 2 connection piping L3 ... 3rd connection piping L4 ... 4th connection piping V1 (1), V1 (2) ... 1st on-off valve V2 ... 2nd on-off valve V3 ... 3rd on-off Valve V4 ... Fourth on-off valve L5 ... Fifth connection pipe R1 ... Throttle mechanism CV1 ... Check valve

Claims (5)

A refrigeration cycle apparatus in which a plurality of low-pressure shell compressors are arranged in parallel between a high-pressure line and a low-pressure line,
An oil tank having an oil inlet opening in an upper space above the lower space in which oil is stored;
A first connecting pipe for connecting an oil inlet provided in the oil tank to a surplus oil outlet provided in each compressor;
A first on-off valve provided on the first connection pipe;
A second connection pipe connecting the oil inlet to the low pressure line;
A second on-off valve provided on the second connection pipe;
In a predetermined oil tank introduction mode, the second on-off valve is opened to allow the oil introduction port to communicate with the low pressure line, while the first on-off valve is opened to provide an excess oil outlet for each compressor. And a control means for communicating with the oil inlet. At least one of the compressors is a variable capacity compressor having a loading / unloading switching function,
In the oil tank introduction mode, when the variable capacity compressor is in an unloading state, the control means opens the first on-off valve corresponding to the variable capacity compressor, and the variable capacity compression The refrigeration cycle apparatus according to claim 1, wherein an excess oil outlet of the machine is communicated with an oil inlet of the oil tank. At least one of the compressors is a fixed capacity compressor,
In the oil tank introduction mode, the control means opens the first on-off valve corresponding to the fixed capacity compressor, and communicates the surplus oil outlet of the fixed capacity compressor with the oil inlet of the oil tank. Then, the first on-off valve is closed, then the first on-off valve corresponding to the variable capacity compressor is opened, and the excess oil outlet of the variable capacity compressor is introduced into the oil tank. The refrigeration cycle apparatus according to claim 2, wherein the refrigeration cycle apparatus communicates with the mouth. A third connection pipe for connecting a refrigerant discharge port of the compressor to the oil introduction port;
A third on-off valve provided on the third connection pipe;
A fourth connection pipe for connecting an oil outlet opening to a lower space of the oil tank to the low-pressure line;
A throttle mechanism provided on the fourth connection pipe,
In a predetermined surplus oil local distribution mode, the control means closes the first on-off valve and the second on-off valve, opens the third on-off valve, and introduces oil into the oil tank into the refrigerant discharge port of the compressor. The refrigeration cycle apparatus according to claim 1, 2 or 3, wherein the refrigeration cycle apparatus is communicated with an opening and the oil discharge port of the oil tank is communicated with a low-pressure line via a throttle mechanism. A fourth on-off valve provided in series with the throttle mechanism on the fourth connection pipe;
A fifth connection pipe branched from the fourth connection pipe on the oil tank side than the fourth on-off valve and connected to the high-pressure line;
A check valve provided on the fifth connection pipe and prohibiting a flow from the high pressure line;
In a predetermined surplus oil distribution mode, the control means closes the first, second, and fourth on-off valves, opens the third on-off valve, and connects the refrigerant discharge port of the compressor to the oil tank oil. 5. The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is in communication with the introduction port, and the oil discharge port of the oil tank is in communication with a high-pressure line through a check valve.