JP2001324230A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent such a malfunction that excess and deficiency of refrigerating machine oil take place in each of compressors (21, 22), while avoiding complication of an oil equalizing structure, in a refrigerating apparatus using the compressors (21, 22) of a high-pressure dome type in a plurality. SOLUTION: When two compressors (21, 22) are provided, an oil collecting part (21o) of a first compressor (21) and a suction pipe (22s) of a second compressor (22) are connected by an oil return passage (34), and an oil collecting part (22o) of the second compressor (22) and a suction pipe (21s) of the first compressor (21) are connected by an oil return passage (35).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus having a plurality of high-pressure dome type compressors, and more particularly to an oil equalizing structure for equalizing the amount of refrigerating machine oil in each compressor. .

[0002]

2. Description of the Related Art Conventionally, a refrigerating apparatus provided with a compression mechanism composed of a plurality of compressors, for example, as shown in FIG.
Compression mechanism (11), four-way switching valve (12), outdoor heat exchanger (13)
, An outdoor expansion valve (14), a liquid receiver (15), and an indoor expansion valve (16)
, An indoor heat exchanger (17) and an accumulator (18) are connected in order to form a refrigerant circuit (10).

In the above refrigeration system, the compression mechanism (11) is
For example, the compressor comprises a first compressor (21) of variable capacity controlled by an inverter and a second compressor (22) of constant capacity controlled on and off, and two compressors (21, 22) are provided. When both are operated, the compressor oil (lubricating oil) is evenly collected in each compressor (21, 22), and when only one compressor is operated, the compressor oil (lubricating oil) of the operating compressor (21) is stopped. ) (See Japanese Patent Application Laid-Open No. 3-17469 (Japanese Patent No. 2865707)). FIG. 16 shows a circuit configuration to which this compression mechanism is applied.

In the refrigerating apparatus described in this publication, two high pressure dome type compressors (21, 22) are used. The high-pressure dome compressor is a compressor in which an oil reservoir is on the discharge side (high-pressure side). Then, an oil separator (51) is provided at a portion where the discharge pipes (21d, 22d) from the two compressors (21, 22) merge, and the oil separator (51) is further connected to the second compressor (22). ), The oil return pipe (52) connected to the oil sump of both compressors (21, 22), and the suction side of both compressors (21, 22). A short-circuited oil communication pipe (54) is provided. Further, a pressure reducing mechanism (55) is provided in the oil return pipe (52), a check valve or a solenoid valve (56) is provided in the oil equalizing pipe (53), and a discharge side and a suction side of the second compressor (22) are provided. Is provided with a check valve (57) (the check valve on the suction side of the second compressor (22) is not shown).

According to this configuration, when both compressors (21, 22) are operated, the oil separated by the oil separator (51) is first discharged to the second oil separator (51).
It is returned to the compressor (22), and further from the second compressor (22)
It is collected by the first compressor (21) via (53). Also, the first
When operating only one compressor (21), the first compressor (21)
Refrigeration oil contained in the refrigerant discharged from the oil separator (5)
After being separated in 1), the oil is returned to the suction side of the stopped second compressor (22) through the oil return pipe (52).
Due to the internal pressure of the second compressor (22), it is not recovered by the second compressor (22) but is recovered by the first compressor (21) through the oil communication pipe (54).

[0006]

However, this conventional structure requires an oil separator (51) and an oil return pipe (52), and also requires an oil equalizing pipe (53) and an oil communication pipe (54). Since it is necessary, there is a problem that the structure is complicated.

For example, when the two compressors (21, 22) are operating and the oil level of the second compressor (22) is lower than the oil leveling pipe (53), the refrigeration Since the machine oil did not flow to the oil equalizing pipe (53), the machine oil was not recovered by the first compressor (21), and there was a possibility that the refrigeration machine oil became insufficient on the first compressor (21) side.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a refrigeration system using a plurality of high-pressure dome-type compressors, which has a complicated oil-equalizing structure. It is also possible to prevent the occurrence of a malfunction such as a shortage of refrigerating machine oil in one of the compressors while avoiding the above problem.

[0009]

According to the present invention, when a plurality of compressors are operated, surplus refrigeration oil is returned from one compressor to another compressor, and only one compressor is operated. In such a case, an oil return passage for returning excess refrigeration oil to the compressor is provided.

[0010] Specifically, a first solution taken by the present invention is a refrigeration system having a compression mechanism (11) in which a plurality of high-pressure dome-type compressors (21, 22, 23) are connected in parallel. The device is assumed. Then, the oil sump (2) of one compressor (21,22,23)
1o, 22o, 23o) and the other compressor (22,23,21)
s, 23s, 21s) as a set and the oil sump (21o,
22o, 23o) and oil return passages (34, 35, 36) communicating the suction pipes (22s, 23s, 21s).

The end of each oil return passage (34, 35, 36) on the compressor side is, for example, an oil reservoir (2, 22) in each compressor (21, 22, 23).
1o, 22o, 23o). However, each passage (3) in each compressor (21,22,23)
The direction of (4, 35, 36) is not limited to this, and may be arbitrarily selected from upward, downward, sideways, and the like as long as a predetermined oil level can be secured.

[0012] A second solution taken by the present invention is:
In the first solution, the gas pipes (19Gs) on the suction side to each of the compressors (21, 22, 23) are connected to the base pipes (31, 31a, 31b) and the base pipes.
(31, 31a, 31b) and the suction pipe of each compressor (21, 22, 23)
(21s, 22s, 23s) and branch pipes (32a, 32b, 32c, 32d) communicating with the oil return passages (34, 35, 36).
3s) via branch pipes (32a, 32b, 32c, 32d), and each branch pipe (32a, 32b, 32c, 32d) has a base pipe (31, 31a, 31d).
An inclined portion (32i) that is inclined upward from the junction with the b) to at least the junction with the oil return passages (34, 35, 36) is provided.

[0013] A third solution taken by the present invention is:
In the second solution, the inclined portion (32i) is connected to at least the stop-side compressor (2) when controlling the capacity of the compression mechanism (11).
2, 23) are provided at the branch pipes (32b, 32d).

A fourth solution taken by the present invention is:
In any one of the first to third solving means, the compression mechanism (11) includes a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity. Between the oil sump (21o) of the first compressor (21) and the suction pipe (22s) of the second compressor (22), and between the oil sump (22o) of the second compressor (22) and the first compressor Oil return passages (34, 35) are provided between the suction pipes (21s) of (21).

[0015] The fifth solution taken by the present invention is:
In any one of the first to third solving means, the compression mechanism (11) includes a first compressor (21) having a variable capacity, a second compressor (22) having a constant capacity, and a second compressor (22) having a constant capacity. An oil sump (21o) of the first compressor (21) and a second compressor.
(22) between the suction pipe (22s) of the second compressor (22) and the suction pipe (23s) of the third compressor (23);
An oil return passage (34, 35, 36) is provided between the oil reservoir (23o) of the compressor (23) and the suction pipe (21s) of the first compressor (21).

[0016] A sixth solution taken by the present invention is:
In any one of the first to fifth solving means, a pressure reducing mechanism (41, 43, 44a, 44b) is provided in each oil return passage (34, 35, 36).

Further, a seventh solution taken by the present invention is:
In the sixth solution, the pressure reducing mechanism is constituted by a capillary tube (41).

An eighth solution taken by the present invention is:
In the sixth solution, each oil return passage (34, 35)
The second passage (34b, 35b) branched from the intermediate point between the first passage (34a, 35a) and the first passage (34a, 35a) to the suction pipe (21s, 22s) side.
b), and the pressure reducing mechanism is connected to the first passage (34a, 35
a) and the solenoid valve (43) and the capillary tube (41) provided in one of the second passages (34b, 35b) (34a, 35a), and the other
(34b, 35b) are provided with a capillary tube (41).

A ninth solution means adopted by the present invention is:
In the sixth solution, the pressure reducing mechanism is connected to the electronic expansion valve (4
4a, 44b).

The tenth solution taken by the present invention is based on the premise that a refrigerating apparatus having a compression mechanism (11) in which a plurality of high-pressure dome type compressors (21, 22) are connected in parallel. I have. The compression mechanism (11) is connected to a first compressor having a variable capacity.
(21) and a second compressor (22) having a constant capacity, and an oil reservoir (21o) of the first compressor (21) and a second compressor (2).
2) between the suction pipe (22s) and the oil sump of the second compressor (22)
An oil return passage (34, 35) having a pressure reducing mechanism (41, 43) is provided between the suction pipe (22o) and the suction pipe (21s) of the first compressor (21). Further, each oil return passage (34, 35) is connected to the first passage (34).
a, 35a) and the first passage (34a, 35a).
s, 22s) and a second passage (34b, 35b) branched to the side, and the pressure reducing mechanism (41, 43) is connected to the first passage (34
a, 35a) and the solenoid valve (43) and the capillary tube (41) provided in one of the second passages (34b, 35b) (34a, 35a), and the capillary tube provided in the other (34b, 35b). The control means (4) configured to close each solenoid valve (43) when the compression ratio becomes higher than a predetermined value during operation of the compression mechanism (11).
7) is provided.

The eleventh solution taken by the present invention is based on the premise that a refrigerating apparatus provided with a compression mechanism (11) in which a plurality of high-pressure dome type compressors (21, 22) are connected in parallel. I have. The compression mechanism (11) is connected to a first compressor having a variable capacity.
(21) and a second compressor (22) having a constant capacity, and an oil reservoir (21o) of the first compressor (21) and a second compressor (2).
2) between the suction pipe (22s) and the oil sump of the second compressor (22)
Oil return passages (34, 35) each having an electronic expansion valve (44a, 44b) are provided between (22o) and the suction pipe (21s) of the first compressor (21). During operation of both compressors (21, 22), when the compression ratio becomes higher than a predetermined value, the opening degree of the electronic expansion valves (44a, 44b) is reduced, and only the first compressor (21) operates. Inside is the second
The electronic expansion valve (4) communicating with the oil sump (22o) of the compressor (22)
When the compression ratio becomes higher than a predetermined value in a state where 4b) is set to fully closed, the control to reduce the opening of the electronic expansion valve (44a) communicating with the oil reservoir (21o) of the first compressor (21). Means (47) are provided.

-Operation- In the first solution, each of the compressors (21, 22, 23) is of a high-pressure dome type, and the refrigerating machine oil is in a high-pressure portion inside the compressor (21, 22, 23). It stays in the oil sump (21o, 22o, 23o). For example, when both compressors are operated using two compressors (21, 22), each compressor (21, 22) has another compressor.
Refrigeration oil is sucked together with the refrigerant from the oil reservoirs (22o, 21o) at (22, 21). When only one compressor (21, 22) is operated, in the operating compressor (21), the refrigerating machine oil is recirculated together with the refrigerant by the high pressure in the compressor (21). At the same time, and is again sucked and collected by the compressor (21).

In the second solution, the branch pipes (32a to 32d) of the suction-side gas pipe (19Gs) are connected at least to the oil return passages (34, 35, 36) from the junction with the base pipe (31). ) And upward to the junction. Conversely, the branch pipe (32a
~ 32d) from the junction with the oil return passage (34,35,36) from the base pipe (3
It will be inclined downward to the junction with 1). For this reason, the refrigerating machine oil and the refrigerant from the operating compressors (21, 22, 23) pass through the oil return passages (34, 35, 36) and the branch pipes (32a to 32d), and the stopped compressors (22 , 23)
After flowing along (32i) to the junction with the base pipe (31), it is collected by the operating compressor (21).

In the third solution, the inclined portion (3
2i) is provided at least in the branch pipes (32b, 32d) to the compressors (22, 23) which stop when controlling the capacity of the compression mechanism (11), so that the operation of the second solving means can be reliably performed. Will be

In the fourth solution, the compression mechanism (11) is composed of a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity. The operation of each of the above-described means is reliably performed. In the fifth means, the first compressor (21) having a variable capacity and the second and third compressors (22,
In the case where the compression mechanism (11) is constituted by the three units (3), the operation of each of the above-mentioned solving means is reliably performed.

In the sixth to ninth solutions, the pressure reducing mechanism (41, 43, 44a, 44b) constituted by the capillary tube (41) and the electronic expansion valve (44a, 44b) is connected to each oil return passage. (34,
35, 36), each compressor (21, 2) while suppressing the flow rate in the oil return passage (34, 35, 36) from becoming excessive.
Refrigeration oil can be recovered in 2,23).

In particular, in the eighth solution, each oil return passage (34, 35) is connected to the first passage (34a, 35a) and the second passage (34b, 35b).
The first passage (34a, 35a) and the second passage (34b,
35b) can be closed by a solenoid valve (43). Therefore, as in the tenth solution, when the compression ratio is high, the refrigerant and the refrigerating machine oil tend to return excessively, whereas the solenoid valve (43) is closed to reduce the flow rate. By opening the solenoid valve (43) and increasing the flow rate, the appropriate amount of refrigerating machine oil is recovered together with the refrigerant. This is the same when both the compressors (21, 22) are operated or when only one is operated.

Also, in the ninth solution means, the flow rate in the oil return passage (34, 35) can be controlled by the electronic expansion valves (44a, 44b). Therefore, as in the eleventh solution, the high-pressure dome-type compressors (21, 22) are used as a variable-capacity first compressor (21) and a constant-capacity second compressor (22). ,
Between the oil sump (21o) of the first compressor (21) and the suction pipe (22s) of the second compressor (22), and between the oil sump (22s) of the second compressor (22).
o) and the suction pipe (21s) of the first compressor (21), when oil return passages (34, 35) having electronic expansion valves (44a, 44b) are provided, both compressors (21 During the operation of (22), when the compression ratio becomes higher than the predetermined value, the opening of the electronic expansion valves (44a, 44b) is reduced, so that an appropriate amount of refrigerating machine oil can be collected in each compressor (21, 22). Also, the return of the refrigerant is not excessive. Also, the first
During operation of the compressor (21) alone, the compression ratio is higher than a predetermined value with the electronic expansion valve (44b) communicating with the oil reservoir (22o) of the second compressor (22) fully closed. Then, by reducing the opening of the electronic expansion valve (44a) communicating with the oil sump (21o) of the first compressor (21), an appropriate amount of the refrigerating machine oil can be collected in the compressor (21), and the refrigerant is returned. Is not too much.

[0029]

According to the first solution, the oil sump (21o, 22o, 23o) of one compressor (21, 22, 23) and the other compressor (22, 23, 24) ) With the suction pipe (22s, 23s, 24s)
(34,35,36), for example, when two compressors (21,22) are used to operate both compressors,
(21,22) at another compressor (22,21) oil sump (22
o, 21o), when only one compressor (21) is operated, the refrigerant oil in the operating compressor (21) is compressed by the high pressure in the compressor (21). The refrigerant (43) flows out of the oil return passage (34) together with the refrigerant, and the compressor (21)
Is sucked again and collected. Therefore, while simplifying the structure, it is possible to prevent the occurrence of a problem such as a shortage of refrigerating machine oil in one compressor.

According to the second and third means, when only one compressor (21) is operated, the refrigerating machine oil flows toward the stopped compressors (22, 23). Without the branch pipe (32a
3232d) and is collected in the operating compressor (21). Therefore, it is possible to prevent the shortage of the refrigerating machine oil in the operating compressor (21), and since the refrigerant and the refrigerating machine oil do not return to the stop-side compressor (22, 23), liquid compression may occur at the time of restart. Can be prevented.

According to the fourth solution, when the compression mechanism (11) is composed of two units, a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity. , The first to third
According to the fifth solution, the compression mechanism (11) is combined with the first compressor (21) having a variable capacity and the second and third compressors having a constant capacity. Machine (22,23) 3
In the case of using a stand, the mechanisms of the first to third solving means can be put to practical use.

Further, according to the sixth to ninth solutions, it is possible to recover an appropriate amount of refrigerating machine oil while suppressing excessive return of the refrigerant in each of the compressors (21, 22, 23). According to the seventh solution, the structure can be simplified because the capillary tube (41) is used for the pressure reducing mechanism.

Further, according to the eighth solution, since the capillary tube (41) and the solenoid valve (43) are used in combination, the refrigerating machine oil is adjusted by adjusting the flow rate according to the compression ratio. While the collecting operation is surely performed, the complexity of the configuration can be suppressed. Furthermore, according to the tenth solution means, the compression mechanism (11) is connected to the first compressor (2
In the case where the apparatus is composed of 1) and the second compressor (22) having a constant capacity, the apparatus can be put into practical use including the specific control of the solenoid valve (43) of the oil return passage (34, 35).

In the ninth solution, the oil return passages (34, 44) are provided by using electronic expansion valves (44a, 44b) for the pressure reducing mechanism.
The flow rate adjustment in 35) can be performed in a form corresponding to the compression ratio. According to the eleventh solution,
When the compression mechanism (11) is composed of a first compressor (21) of variable capacity and a second compressor (22) of constant capacity, the oil return passage (34, 3
The device can be put into practical use including the specific control of the electronic expansion valves (44a, 44b) of 5).

[0035]

Embodiment 1 -Configuration- Embodiment 1 of the present invention will be described below in detail with reference to the drawings.

<Circuit Configuration> FIG. 1 is a refrigerant circuit diagram of a refrigeration system (1) according to the first embodiment.
Is a multi-type air conditioner used in buildings, etc., and a plurality of indoor units (2) are one outdoor unit
(3) is connected in parallel.

The refrigerant circuit (10) of the air conditioner includes a compression mechanism (11), a four-way switching valve (12), an outdoor heat exchanger (13),
An outdoor expansion valve (14), a liquid receiver (15), an indoor expansion valve (16),
The indoor heat exchanger (17) and the accumulator (18) are sequentially connected by a refrigerant pipe (19) to form a closed circuit for performing a vapor compression refrigeration cycle. Each indoor unit (2) is provided with an indoor expansion valve (16) and an indoor heat exchanger (17), and other equipment is provided in the outdoor unit (3).
The outdoor unit (3) is provided with an outdoor fan (3f) for blowing air to the outdoor heat exchanger (13), and the indoor unit (2) is for indoor air blowing to the room through the indoor heat exchanger (17). A fan (2f) is provided.

The compression mechanism (11) is composed of two high-pressure dome type compressors (21, 22) connected in parallel as shown in FIG. 2, which is a partially enlarged view of FIG. Two compressors (2
1, 22), a variable capacity first compressor (21) whose rotation speed is controlled by an inverter and a constant capacity second compressor (22) whose on / off control is performed are used. And the gas pipe (19Gs) on the suction side from the accumulator (18) is
The branch pipes (32a, 32b) are branched and connected to the suction pipes (21s, 22s) of the compressors (21, 22), while the discharge pipes (21d, 22d) of the compressors (21, 22). ) Are merged and connected to the discharge side gas pipe (19Gd). The discharge pipe (22d) of the second compressor (22) is provided with a check valve (33) for preventing backflow of the refrigerant.

In the compression mechanism (11), up to a predetermined capacity, only the first compressor (21) is operated with the rotation speed controlled by the inverter while the second compressor (22) is stopped. .
In addition, when a capacity exceeding a predetermined level is required, the second compressor
In a state where (22) is started, the first compressor (21) is operated with the rotation speed controlled by the inverter. As described above, the capacity of the compression mechanism (11) is controlled according to the required capacity.

<Refrigeration oil recovery structure> Each compressor (21, 22)
Each of the compressors has an oil reservoir (21o, 22o) for storing refrigeration oil in a high pressure portion inside the compressor (21, 22). Then, an oil sump (21o, 22o) of one compressor (21, 22) and a suction pipe (22s, 21s) of another compressor (22, 21) are set as one set, and Oil return passages (34, 35) are provided for communicating the oil reservoirs (21o, 22o) and the suction pipes (22s, 21s).

More specifically, the first compressor (21) is connected via a branch pipe (32b) between an oil reservoir (21o) and a suction pipe (22s) of the second compressor (22). An oil return passage (34) is provided, and the second
A second oil return passageway (3) is provided between the oil reservoir (22o) of the compressor (22) and the suction pipe (21s) of the first compressor (21) via a branch pipe (32a).
5) is provided. Each oil return passage (34, 35) is provided with a capillary tube (41) as a pressure reducing mechanism. The end of each oil return passage (34, 35) on the compressor side is
Each of the compressors (21, 22) is configured to open downward toward the oil reservoir (21o, 22o).

Although not shown, the discharge-side gas pipe
(19Gd), an oil separator is provided at the part where the discharge pipes (21d, 22d) of the compressors (21, 22) merge to separate the refrigerating machine oil from the refrigerant and return it to the accumulator (18). You may.

-Operation- Next, the operation of the air conditioner (1) will be described.

<Air-conditioning operation> First, the compression mechanism (11) operates only the first compressor (21) up to a predetermined capacity, and controls the number of revolutions of the first compressor (11) to obtain a necessary amount. Corresponds to capacity. Also, if the capacity exceeding the specified capacity is required,
The rotation speed of the first compressor (21) is controlled in a state where the second compressor (22) is also started, and the required capacity is accommodated.

As described above, while controlling the capacity of the compression mechanism (11), the four-way switching valve (12) is set to the connection state shown by the solid line in FIG. 1 during the cooling operation, and the four-way switching valve during the heating operation. (12) is set to the connection state indicated by the broken line.

During the cooling operation, the gas refrigerant discharged from the compression mechanism (11) flows into the outdoor heat exchanger (13) through the four-way switching valve (12) and exchanges heat with the outdoor air. Condense. The liquid refrigerant condensed in the outdoor heat exchanger (13) passes through the outdoor expansion valve (14) that is set to be fully open during the cooling operation, and
While storing the surplus in (15), it is diverted to each indoor unit (2).

In each indoor unit (2), the refrigerant is decompressed to a predetermined low pressure by the indoor expansion valve (16), and the indoor heat exchanger (17)
Flows into. In the indoor heat exchanger (17), the refrigerant exchanges heat with the indoor air and evaporates, and at that time, the cooled air is blown into the room by the indoor fan (2f) to cool the room.
In the stopped indoor unit (2), the indoor expansion valve (16) is controlled to be fully closed so that the refrigerant does not flow to the indoor heat exchanger (17), and the indoor fan (2f) also stops. I do. Also,
The air conditioner (1) is configured such that the capacity of the compression mechanism (11) is controlled according to the operation state of the indoor unit (2).

The gas refrigerant flowing out of the indoor heat exchanger (17)
After flowing into the accumulator (18) via the four-way switching valve (12) and the liquid refrigerant is separated by the accumulator (18), the compression mechanism
Return to (11). During the cooling operation, the refrigerant circulates through the refrigerant circuit (10) in this manner, and a predetermined room is cooled.

During the heating operation, the gas refrigerant discharged from the compression mechanism (11) flows into each indoor heat exchanger (17) through the four-way switching valve (12) and exchanges heat with the indoor air. To condense. And the air heated at that time is the indoor fan (2f)
Is blown out into the room, and the room is heated. In addition,
Also in this case, in the stopped indoor unit (2), the indoor expansion valve (16) is controlled to be fully closed so that the refrigerant does not flow through the indoor heat exchanger (17), and the indoor fan (2f ) Also stops. Further, the capacity of the compression mechanism (11) is configured to be controlled according to the operation state of the indoor unit (2) at the time of the heating operation as well as at the time of the cooling operation.

The liquid refrigerant flowing out of the indoor heat exchanger (17) in the operating indoor unit (2) passes through the indoor expansion valve (16) which is set to be fully open, and is transferred to the receiver (15). The excess flows into the outdoor expansion valve (14) while being stored, and is reduced to a predetermined low pressure. Then, heat is exchanged with outdoor air in the outdoor heat exchanger (13) to evaporate, and after flowing into the accumulator (18) through the four-way switching valve (12), the liquid refrigerant is separated by the accumulator (18),
Return to the compression mechanism (11). During the heating operation, the refrigerant circulates through the refrigerant circuit (10) in this manner, and a predetermined room is heated.

<Recovery of Refrigeration Oil> Next, the operation of recovering the refrigeration oil will be described.

In the first embodiment, each compressor (21, 2
2) is a high-pressure dome type, and the refrigerating machine oil is a compressor (21,22)
Stays in the oil reservoirs (21o, 22o) in the high-pressure portion inside of the oil reservoir. For example, when both compressors (21, 22) are operated, the refrigerating machine oil is pushed out together with the refrigerant into the oil return passages (34, 35) with the operation of each compressor (21, 22). Refrigeration oil is collected from one compressor (21, 22) to the other compressor (22, 21).

In this case, if a large amount of refrigerating machine oil is stored in one of the compressors (21, 22),
Although it is sucked into the compressor (22, 21), it is not sucked from the compressor having a small amount of refrigerating machine oil to the compressor having a large amount of refrigerating machine oil.

When only one compressor (21, 22) is operated, in the operating first compressor (21), the refrigerating machine oil is cooled together with the refrigerant by the high pressure in the first compressor (21). It flows out of the first oil return passage (34). Then, the outflowing refrigerant and the refrigerating machine oil are sucked and collected by the first compressor (21). Therefore, it is possible to prevent the refrigerating machine oil and the refrigerant from being accumulated in the stopped second compressor (22).

In each oil return passage (34, 35), a capillary tube (41) is provided as a pressure reducing mechanism, so that the flow rates of the refrigerant and the refrigerating machine oil in the oil return passages (34, 35) can be adjusted appropriately. Refrigerating machine oil is collected in each compressor (21, 22) while keeping it down.

-Effects of First Embodiment- According to the first embodiment, the oil sump (2) of the first compressor (21)
1o) and the suction pipe (22s) of the second compressor (22) are connected by a first oil return passage (34), and the oil sump (22o) of the second compressor (22) and the first compressor (22) are connected. A second oil return passage (35) with the suction pipe (21s) of (21).
When both compressors (21, 22) are operated by the communication at (2), each compressor (21, 22) is connected to the other compressor (22, 2).
Refrigeration oil is inhaled from the oil sump (22o, 21o) of 1),
The amount of oil in the refrigerator is made uniform. Also, the first compressor (21)
In the case of operating only the stand, in the operating first compressor (21), the refrigerating machine oil flows out of the first oil return passage (34) together with the refrigerant due to the high pressure in the first compressor (21) and the second oil returns. 1
It is sucked again by the compressor (21) and collected. Therefore,
While simplifying the structure, it is possible to prevent the occurrence of problems such as excessive or insufficient refrigerating machine oil. In particular, since the capillary tube (41) is used for the decompression mechanism, the performance can be prevented from deteriorating due to an increase in the flow rate of the refrigerant in the oil return passages (34, 35) while simplifying the structure.

[0057]

Embodiment 2 In Embodiment 2 of the present invention, as shown in FIG. 3, a suction-side gas pipe (19 Gs) to a compressor (21, 22) is used.
Is configured differently from the first embodiment, and the other parts are configured in the same manner as the first embodiment.

Gas pipe on the suction side to compressors (21, 22) (19 Gs)
Is a base pipe (31) and a branch pipe (32a, 32b) to each compressor (21, 22).
It is composed of In the second embodiment, each of the branch pipes (32a, 32b) includes an inclined portion (32i) that is inclined upward from a junction with the base pipe (31). The inclined portion (32i) may be formed from a junction with the base pipe (31) to at least a junction with the oil return passages (34, 35). FIG. 3 shows a branch pipe (32a, 3a) to both compressors (21, 22).
2b) shows an example in which an inclined portion (32i) is provided.
(32i) may be provided at least in the branch pipe (32b) on the side of the second compressor (22) which becomes the stop-side compressor when controlling the capacity of the compression mechanism (11).

FIG. 4 shows a branch pipe of the suction-side gas pipe (19 Gs).
(32a, 32b) and an external view in which an oil return passage (34, 35) is connected. As shown in the figure, the base pipe (31) of the suction-side gas pipe (19Gs) is connected to each compressor (21, 2) through a Y-shaped pipe joint (42).
It is connected to the branch pipe (32a, 32b) to 2). And
The second pipe is attached to the slope (32i) of the branch pipe (32a) to the first compressor (21).
A second oil return passage (35) from the compressor (22) is connected to the second oil return passage (35).
A first oil return passage (34) from the first compressor (21) is connected to an inclined portion (32i) of a branch pipe (32b) to the compressor (22).

-Operating Operation- Also in the second embodiment, the refrigerant circulation operation during the cooling operation and the heating operation is performed in the same manner as in the first embodiment.

On the other hand, the operation of collecting the refrigerating machine oil is performed as follows.

That is, when both the compressors (21, 22) are operated, the refrigerating machine oil and the refrigerant are returned to the oil return passage (34) together with the operation of the compressors (21, 22) as in the first embodiment. , 35) and is sucked into the other compressor (22, 21) to recover the refrigerating machine oil and the refrigerant. In this case as well, if a large amount of refrigerating machine oil is stored in one of the compressors (21, 22), the other compressor (22, 21) sucks the refrigerating machine oil, and a large amount of the refrigerating machine oil is used. Since it is not sucked into the compressor, the amount of refrigerating machine oil for each compressor (21, 22) is made uniform.

When only one first compressor (21) is operated, the refrigerating machine oil flows out of the first oil return passage (34) together with the refrigerant due to the high pressure in the first compressor (21). The refrigerant and the refrigerating machine oil that have flowed out are sucked and collected by the compressor (21). In the second embodiment, the second branch pipe (32b) of the suction-side gas pipe (19Gs) is connected to at least the first branch pipe from the junction with the base pipe (31).
It is inclined upward to the junction with the oil return passage (34). Conversely, the branch pipe (32b) is connected to the first oil return passage (3).
It is inclined downward from the junction with 4) to the junction with the base pipe (31). Therefore, since the refrigerant and the refrigerating machine oil flowing out of the first compressor (21) flow downward along the slope, the refrigerant and the refrigerating machine oil do not flow toward the stopped second compressor (22), but the base pipe (3
After flowing toward the junction with 1), the first compressor (2
It is surely collected in 1).

-Effects of Second Embodiment- As described above, according to the second embodiment, it is possible to reliably prevent the refrigerating machine oil and the refrigerant from accumulating in the stopped second compressor (22). Liquid compression can be reliably prevented from occurring when the second compressor (22) is restarted. In addition, the first
The occurrence of shortage of refrigerating machine oil in the compressor (21) can also be prevented.

[0065]

Third Embodiment As shown in FIG. 5, a third embodiment of the present invention is different from the first embodiment in that each oil return passage (34, 35) has a different structure.

Specifically, each oil return passage (34, 35)
Passages (34a, 35a) and the suction pipe (21
s, 22s) and a second passage (34b, 35b) branched to the side. The pressure reducing mechanism includes a capillary tube (41) and a solenoid valve (43) provided in the first passage (34a, 35a), and a capillary tube (41) provided in the second passage (34b, 35b). Have been.

In the third embodiment, a controller (control means) (47) for controlling the operation of the air conditioner (1) is provided.
However, during operation of the compression mechanism (11), each solenoid valve (43) is configured to close when the compression ratio becomes higher than a predetermined value. Further, in order to perform control according to the compression ratio by the controller (47), a low-pressure pressure sensor (45) is provided on the suction-side gas pipe (19Gs), and a high-pressure pressure sensor (45) is provided on the discharge-side gas pipe (19Gd). 46) is provided.

-Operating Operation- Also in the third embodiment, the basic flow of the refrigerant during the cooling operation and the heating operation is the same as in the first embodiment, and the air conditioning operation itself is performed according to the first embodiment.

On the other hand, the operation of collecting the refrigerating machine oil is performed as follows.

That is, when the compression ratio is higher than a predetermined value due to a change in operating conditions such as a change in the high pressure, the solenoid valve (43) of the first passage (34a, 35a) is closed, and the compression ratio is reduced. When the ratio is lower than the predetermined value, the solenoid valve (43) is opened.

By doing so, in the configuration of the first embodiment, depending on the degree of decompression by the capillary tube (41), it is difficult for the refrigerating machine oil to return at a low compression ratio, or at a high compression ratio. In the third embodiment, the two passages (34a, 35a, 34b, 35b) are used when the compression ratio is low, so that the refrigerating machine oil is easily returned, and By using only one passage (34b, 35b) at the time of the compression ratio, it is possible to prevent the refrigerating machine oil and the refrigerant from returning too much.

The above operation is performed both when the compressors (21, 22) are operated and when only the first compressor (21) is operated.

-Effects of Third Embodiment- According to the third embodiment, the refrigerating machine oil can be easily returned when the compression ratio is low, so that the reliability of the mechanism can be improved. Since it is possible to prevent the refrigerating machine oil and the refrigerant from flowing excessively, it is possible to suppress a decrease in performance.

[0074]

Embodiment 4 As shown in FIG. 6, Embodiment 4 of the present invention is different from Embodiment 1 in that the oil return passages (34, 35) are configured differently.

Specifically, each oil return passage (34, 35) is provided with a capillary tube (41) as a pressure reducing mechanism in the first embodiment.
In contrast to the configuration in which
In this configuration, an electronic expansion valve (44a, 44b) is used instead of the capillary tube (41) as a pressure reducing mechanism. Specifically, a first electronic expansion valve (44a) is provided in the first oil return passage (34), and a second electronic expansion valve (44b) is provided in the second oil return passage (35).

Further, the gas pipe on the suction side of the compression mechanism (11) (19G
A low pressure sensor (45) is provided in s), and a high pressure sensor (46) is provided in the discharge side gas pipe (19Gd) of the compression mechanism (11). Then, a controller (control means) (47) for controlling the operation of the air conditioner (1) is provided with pressure sensors (45, 4).
6) and the electronic expansion valves (44a, 44b). During operation of both compressors (21, 22), when the compression ratio becomes higher than a predetermined value, the controller (47) controls both electronic expansion valves (44).
a, 44b) is made smaller by reducing the opening. Also,
During the operation of only the first compressor (21), while the second electronic expansion valve (44b) communicating with the oil sump (22o) of the second compressor (22) is fully closed, the compression ratio exceeds a predetermined value. Is higher, the opening degree of the first electronic expansion valve (44a) communicating with the oil sump (21o) of the first compressor (21) is reduced and the state is reduced.

-Operating operation- Also in the fourth embodiment, the basic refrigerant flow during the cooling operation and the heating operation is the same as in the first embodiment, and the air conditioning operation itself is performed according to the first embodiment. .

On the other hand, the operation of collecting the refrigerating machine oil is performed as follows in accordance with the flowchart of FIG.

First, in step ST1, A: Com
It is determined whether the first compressor (21) indicated by p is on or off.
When the first compressor (21) is off, the second compressor (2)
2) is also stopped, and at this time, the determination in step ST1 is repeated. That is, in step ST1, the first
Waiting for the compressor (21) to start.

If it is determined in step ST1 that the first compressor (21) is turned on, the process proceeds to step ST2 where B: C
It is determined whether the second compressor (22) indicated as omp is on or off. If it is on, the process proceeds to step ST4, and if it is off, the process proceeds to step ST5. In steps ST4 and ST5, it is necessary to determine whether the compression ratio is higher than a predetermined value.
In ST3, detection data of the low pressure sensor (45) and the high pressure sensor (46) is given to the controller (47) in advance.

When the determination in step ST4 is performed, both compressors
(21, 22) is in operation. When it is determined that the compression ratio is high (the compression ratio is higher than a predetermined value) under these conditions, in step ST7, both electronic expansion valves (44
a, 44b) (in the figure, the first electronic expansion valve (44a) is represented as EVA, and the second electronic expansion valve (44b) is represented as EVB). Oil return passage (3
4,35) to make it difficult to flow. Step ST
If it is determined that the compression ratio is lower than the predetermined value as a result of the determination in step 4, both electronic expansion valves (44a, 44b) are determined in step ST7.
Open more than at high compression ratio, and the refrigerating machine oil
35) Make it easy to flow so that collection can be performed reliably. Note that in this flowchart, N2pls and N1pls
s indicates the degree of opening of the electronic expansion valves (44a, 44b), and indicates that N2pls narrows the electronic expansion valves (44a, 44b) more than N1pls.

On the other hand, when performing the determination in step ST5,
Only the first compressor (21) is operating. At this time, when it is determined that the compression ratio is high, the second compression is performed in step ST8.
The electronic expansion valve (44b) is fully closed, and the first electronic expansion valve (44a) is closed.
At a lower compression ratio than at a low compression ratio. If it is determined in step ST5 that the compression ratio is lower than the predetermined value,
In step ST9, the second electronic expansion valve (44b) is fully closed, and the first electronic expansion valve (44a) is opened more than when the compression ratio is high. As described above, when only the first compressor (21) is operating, the second electronic expansion valve (44b) is closed and the opening of the first electronic expansion valve (44a) is adjusted. I have.

-Effects of the Fourth Embodiment- According to the fourth embodiment, as in the third embodiment, the refrigerating machine oil can be easily returned at a low compression ratio, so that the reliability can be improved. When the compression ratio is high, it is possible to prevent the refrigerating machine oil and the refrigerant from returning excessively, so that a decrease in performance can be suppressed. Moreover, in the fourth embodiment, since the electronic expansion valves (44a, 44b) are used, the degree of opening is more finely adjusted according to the compression ratio, so that the reliability can be further improved as compared with the third embodiment. It is possible to prevent the performance from decreasing.

[0084]

Fifth Embodiment A fifth embodiment of the present invention relates to an air conditioner in which a compression mechanism (11) is composed of three compressors (21, 22, 23) as shown in FIG. is there. The refrigerant circuit (10) of the air conditioner (1) is configured in the same manner as the above embodiments, except that the configuration of the compression mechanism (11) is different.

The compression mechanism (11) is composed of a variable capacity first compressor (21) whose rotation speed is controlled by an inverter and constant capacity second and third compressors (22, 23) whose on / off control is performed. It is configured. Then, the suction pipe (21s, 2s) of each compressor (21, 22, 23)
2s, 23s) are connected to each other, and the discharge pipes (21d, 22d, 23d) are connected to each other, so that three compressors (21, 22, 23) are connected in parallel.

Specifically, the base pipe of the suction-side gas pipe (19 Gs)
(31) branches into a first base pipe (31a) and a second base pipe (31b), and the first compressor (21) and the second compressor ( 22) are connected in parallel via first and second branch pipes (32a, 32b), and the first compressor (2) is connected to the second base pipe (31b).
1) and the third compressor (23) are connected in parallel via third and fourth branch pipes (32c, 32d). As for the first compressor (21), one suction pipe (21s) is connected to the first base pipe (31a) and the second base pipe via the first branch pipe (32a) and the third branch pipe (32c). Tube (31
b) are connected to each other.

On the other hand, the discharge side is the discharge pipe of the first compressor (21).
(21d) and the discharge pipe (22d) of the second compressor (22) merge and are connected to the discharge-side gas pipe (19Gd), and the discharge pipe of the third compressor (23)
(23d) joins the discharge pipe (21d) of the first compressor (21). And discharge pipes of the second compressor (22) and the third compressor (23).
The (22d, 23d) is provided with a check valve (33) which allows only the outflow of the refrigerant from the second and third compressors (22, 23).

The oil return passages (34, 35, 36) are provided with an oil reservoir (21o) of the first compressor (21) and the second compressor (2).
The branch pipe (32b) to the suction pipe (22s) of 2) is the first oil return passage
(34), the oil reservoir (22o) of the second compressor (22) and the branch pipe (32d) to the suction pipe (23s) of the third compressor (23) are connected to the second oil return passage ( 35), a branch pipe to the oil sump (23o) of the third compressor (23) and the suction pipe (21s) of the first compressor (21)
(32c) are connected by a third oil return passage (36). The third oil return passage (36) is connected to the branch pipe on the first base pipe (31a) side.
(32a). In addition, each suction pipe (21s, 22s, 23
The branch pipes (32a, 32b, 32c, 32d) connected to the first base pipe (31a) and the second base pipe (31b) are respectively configured to be inclined upward from the junction with the first base pipe (31a) and the second base pipe (31b). Have been.

FIG. 9 shows a branch pipe of the suction-side gas pipe (19 Gs).
(32b, 32c, 32d) and an external view in which oil return passages (34, 35, 36) are connected. As shown in the figure, the suction side gas piping (1
The 9Gd) base pipe (31) branches into two first and second base pipes (31a, 31b) via a Y-shaped pipe joint (42), and the first base pipe (31a) is connected to the second branch pipe. The first compressor (21) is connected to the suction side of the second compressor (22) through a pipe (32b), and is connected to the inclined portion (32i) of the branch pipe (32b).
Oil return passage (34) is connected. Although not shown in FIG. 9, the first base pipe (31a) is a first branch pipe (32a).
Is also connected to the suction side of the first compressor (21).

The second base pipe (31b) is a Y-type pipe joint.
(42) branches into a third branch pipe (32c) and a fourth branch pipe (32d), the third branch pipe (32c) being connected to the suction side of the first compressor (21), A pipe (32d) is connected to the suction side of the third compressor (23). Then, the inclined portion (3) of the third branch pipe (32c)
An oil return passage (36) from the third compressor (23) is connected to 2i), and a second compressor (22) is connected to the inclined portion (32i) of the fourth branch pipe (32d).
An oil return passage (35) is connected.

Each compressor (21, 22, 23) is controlled in capacity as shown in FIG. 10 in order to obtain the required capacity as a refrigeration system. That is, up to the first predetermined capacity Q1, the first compressor (22) and the third compressor (23) are stopped and the first compressor (23) is stopped.
Only (21) is operated with the rotation speed controlled by the inverter. In addition, the second compressor (22) is started and the third compressor is operated from the first predetermined capacity Q1 to the second predetermined capacity Q2.
In a state where (23) is stopped, the first compressor (21) is operated with the rotation speed controlled by the inverter. Furthermore, when the second predetermined capacity Q2 or more, when the second compressor (22) and the third compressor (23) are started, the first compressor (21) is operated with the rotation speed controlled by the inverter. Is done. By controlling as described above, the capacity of the compression mechanism (11) is controlled to a predetermined value.

-Operating operation- The air conditioner of the fifth embodiment has a compression mechanism as described above.
The cooling operation and the heating operation are performed while performing the capacity control of (11), and a predetermined capacity can be obtained. The operation of circulating the refrigerant during the air-conditioning operation is the same as in the first embodiment.

On the other hand, the operation of collecting the refrigerating machine oil is performed as follows.

First, when only one compressor (21) is operated, in FIG. 11, the refrigerant flows according to the solid arrow, and the refrigerating machine oil flows according to the broken arrow. Specifically, the refrigerant is branched from the base pipe (31) to the first and second base pipes (31a, 31b), and then passes through the first and third branch pipes (32a, 32c) to form the suction pipe (21s). And are sucked into the first compressor (21). Then, it is compressed to a predetermined high pressure and flows out of the discharge pipe (21d), passes through the discharge-side gas pipe (19Gd), and is connected to the outdoor heat exchanger (13).
Or it flows to the indoor heat exchanger (17). Second compressor (22)
And the discharge pipe (22d, 23d) of the third compressor (23) is provided with a check valve (33), so that the refrigerant discharged from the first compressor (21) is supplied to the outdoor heat exchanger (13) or It flows only to the indoor heat exchanger (17) side.

Since the refrigerant discharged from the first compressor (21) contains refrigeration oil, the refrigeration oil also circulates in the refrigerant circuit (10). When the refrigerating machine oil returns to the first compressor (21) and exceeds a predetermined level in the oil sump (21o), it is pushed out of the oil return passage (34) together with the refrigerant and flows out.
The outflowing refrigerant and the refrigerating machine oil flow downward from the junction of the second branch pipe (32b) along the inclined portion (32i) of the branch pipe (32b), and are mixed with the gas refrigerant on the suction side. It is sucked into the compressor (21). Therefore, the refrigerating machine oil in the first compressor (21) does not flow to the second compressor (22) or the third compressor (23), and the refrigerating machine oil of the first compressor (21) reaches a predetermined level. Will be maintained.

Next, when the first compressor (21) and the second compressor (22) are operated, as shown in FIG. 12, the refrigerant is supplied to the base pipe (31).
From the first and second base pipes (31a, 31b), and then through the first, second, and third branch pipes (32a, 32b, 32c), to the first and second compressors (21, 22). Inhaled. Then, each of the compressors (21, 22) is compressed to a predetermined high pressure, flows out of the discharge pipes (21d, 22d), circulates through the refrigerant circuit (10), and returns to the compressors (21, 22).
Since the discharge pipe of the third compressor (23) is provided with the check valve (33), the refrigerant does not flow backward from the discharge pipe (23d) to the third compressor (23).

When the refrigerating machine oil in the first compressor (21) exceeds a predetermined level, it is pushed out of the oil return passage (34) together with the refrigerant and flows out. The refrigerating machine oil and the refrigerant that have flowed out have the oil return passageway (34) joined to the second branch pipe (32b), and the junction point of the oil is returned to the second compression pipe from the suction pipe (21s) of the first compressor (21). Since it is provided close to the suction pipe (22s) of the compressor (22), it is merged with the suction gas refrigerant and sucked into the second compressor (22). Similarly, when the refrigerating machine oil and the refrigerant in the second compressor (22) exceed a predetermined level, they are pushed out of the oil return passage (35) and flow out. Then, when reaching the junction with the fourth branch pipe (32d), the second branch pipe (32d) is moved along the inclined portion (32i).
It flows in the direction of the junction with the base pipe (31b), merges with the suction gas refrigerant, and is sucked into the first compressor (21).

As described above, when the two compressors (21, 22) are operating, the refrigerating machine oil in the first compressor (21) and the refrigerating machine oil in the second compressor (22) are in the third state. Without flowing into the compressor (23),
The first compressor (21) and the second compressor (22) during operation collect the fluid and maintain the predetermined level in the first and second compressors (21, 22).

Next, when all three compressors (21, 22, 23) are operated, as shown in FIG. 13, the refrigerant flows from the base pipe (31) to the first and second base pipes (31a, 31b). ), Each branch pipe (32a ~
It is sucked into all the compressors (21, 22, 23) through 32d). Then, each of the compressors (21, 22, 23) is compressed to a predetermined high pressure, flows out of the discharge pipes (21d, 22d, 23d), merges in the discharge-side gas pipe (19Gd), and flows through the refrigerant circuit (10). Circulate. At this time, the refrigerant circuit (10) with the refrigerating machine oil also contained in the refrigerant
Circulate.

In this case, when the refrigerating machine oil in the first compressor (21) exceeds a predetermined level, it is recovered by the second compressor (22) together with the refrigerant in the same flow as in FIG. In addition, the second compressor (2
When the refrigerating machine oil in 2) exceeds a predetermined level, it is pushed out of the oil return passage (35) together with the refrigerant and flows out, and the fourth branch pipe
(32d), after reaching the junction with the first compressor (2
The suction pipe (23s) of the third compressor (23) rather than the suction pipe (21s) of 1)
, And is merged with the suction gas refrigerant to be sucked into the third compressor (23). Furthermore, the third compressor
When the refrigerating machine oil in (23) exceeds a predetermined level, it flows out of the oil return passage (36) together with the refrigerant and reaches a junction with the third branch pipe (32c). (21) suction pipe
(21s), it merges with the suction gas refrigerant and is sucked into the first compressor (21).

When all three compressors (21, 22, 23) are operating, the refrigerating machine oil is maintained at a predetermined level for all the compressors (21, 22, 23) as described above. It will be.

According to the fifth embodiment, when the compression mechanism (11) is composed of three compressors (21, 22, 23), each of the compressors (21, 22, 23) Oil return passage between (34,35,36)
Refrigerator oil can be maintained at a predetermined level in each of the compressors (21, 22, 23) only by providing the compressor. Therefore, it is possible to prevent a failure such as a shortage of refrigerating machine oil in one of the compressors (21, 22, 23) while avoiding a complicated configuration.

[0103]

Other Embodiments of the Invention The present invention may be configured as follows with respect to the above embodiment.

For example, in each of the above embodiments, the present invention is applied to the air conditioner (1). However, the present invention is applicable to any refrigerating apparatus in which the compression mechanism (11) is composed of a plurality of high-pressure dome compressors. For example, the present invention is not limited to the air conditioner and can be applied to the present invention.

The pressure reducing mechanism (41, 43) (44) having the structure shown in Embodiments 3 and 4 is an oil return passage of the compression mechanism (11) of Embodiment 2 in which the branch pipes (32a, 32b) are inclined. (34, 35) or the oil return passage (34, 3) of the compression mechanism (11) of the fifth embodiment.
5, 36).

Further, the compression mechanism (11) is not limited to the combination of the variable capacity compressor (21) controlled by the inverter and the fixed capacity compressor (22, 23) for performing the on / off control. (11) Other combinations, such as each other,
The capacity control method including on / off control may be changed as appropriate.

Further, in each of the above embodiments, each oil return passage
The end on the compressor side of (34, 35, 36) is configured to open downward toward the oil sump (21o, 22o, 23o) in each compressor (21, 22, 23). However, as long as a predetermined oil level can be secured, the direction of the opening of each passage (34, 35, 36) in each compressor (21, 22, 23) can be arbitrarily selected from upward, downward, sideways, etc. You just have to choose. FIG. 14 (a) shows an example in which the direction is upward,
FIG. 14B shows an example in which the camera is turned sideways.

Also, for example, the suction side gas pipe shown in FIG.
The connection example between the (19Gs) branch pipes (32a, 32b) and the oil return passages (34, 35) may be changed as shown in FIG. In this example, the inclined portion (32i) of FIG. 4 is not provided, and an oil return passage (35) from the first compressor (21) is provided in a vertical portion of the branch pipe (32b) to the second compressor (22). An oil return passage (34) from the second compressor (22) is connected to a vertical portion of the branch pipe (32a) to the first compressor (21). Therefore, when only the first compressor (21) is operated, the refrigerating machine oil flowing out of the first compressor (21) is discharged from the second compressor (2).
It is collected by the first compressor (21) without flowing to the two compressors (2).
During the operation of (1,22), the refrigerating machine oil flowing out of each compressor (21,22) flows to the other compressor (22,21), and the refrigerating machine oil is collected in the same manner as in the example of FIG. be able to.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged view of a compression mechanism in the refrigerant circuit of FIG.

FIG. 3 is an enlarged view showing a compression mechanism of the air-conditioning apparatus according to Embodiment 2 of the present invention.

4 is an external view in which a suction pipe and an oil return passage are connected in the compression mechanism of FIG. 3;

FIG. 5 is an enlarged view illustrating a compression mechanism of an air-conditioning apparatus according to Embodiment 3 of the present invention.

FIG. 6 is an enlarged view showing a compression mechanism of an air conditioner according to Embodiment 4 of the present invention.

FIG. 7 is a flowchart illustrating control at the time of refrigerating machine oil recovery in the air-conditioning apparatus according to Embodiment 4.

FIG. 8 is an enlarged view showing a compression mechanism of an air conditioner according to Embodiment 5 of the present invention.

9 is an external view in which a suction pipe and an oil return passage are connected in the compression mechanism of FIG. 8;

FIG. 10 is a diagram showing an operation state when controlling the capacity of a compression mechanism in a fifth embodiment.

FIG. 11 is a diagram showing flows of a refrigerant and refrigerating machine oil when one compressor is operated by the compression mechanism of FIG. 8;

FIG. 12 is a diagram showing flows of a refrigerant and refrigerating machine oil when two compressors are operated by the compression mechanism of FIG. 8;

FIG. 13 is a diagram showing flows of the refrigerant and the refrigerating machine oil when three compressors are operated by the compression mechanism of FIG. 8;

FIGS. 14A and 14B are diagrams showing examples in which the direction of each passage is changed in each compressor. FIG.

FIG. 15 is a diagram showing a modification of FIG. 4;

FIG. 16 is a refrigerant circuit diagram of a conventional refrigeration apparatus.

[Explanation of symbols]

 (1) Refrigeration system (10) Refrigerant circuit (11) Compression mechanism (19Gs) Intake side gas pipe (21) First compressor (22) Second compressor (23) Third compressor (21o, 22o, 23o) Oil reservoir (21s, 22s, 23s) Suction pipe (31,31a, 31b) Base pipe (31i) Inclined section (32a, 32b, 32c, 32d) Branch pipe (34,35,36) Oil return passage (34a, 35a) First passage (34b, 35b) Second passage (41) Capillary tube (pressure reducing mechanism) (43) Solenoid valve (pressure reducing mechanism) (44a, 44b) Electronic expansion valve (pressure reducing mechanism) (47) Controller (control means) )

Continued on the front page (72) Inventor Toshihiko Takayama 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd. Sakai Seisakusho Kanaoka Factory F-term (reference) 3H076 AA01 AA16 AA40 BB04 BB17 BB28 BB31 BB36 BB43 CC07 CC62 CC69 CC70 CC94 CC95

Claims (11)

[Claims] A plurality of high-pressure dome-type compressors (21, 22, 23)
Is a refrigeration system having a compression mechanism (11) connected in parallel, wherein the oil sump (21o, 22o, 23o) of one compressor (21, 22, 23) and the other compressor (22,23,21) suction pipes (22s, 23s, 21s) as a set, and for each set the oil sump (21o, 22o, 23o) and suction pipe
(22s, 23s, 21s). A refrigerating apparatus provided with an oil return passage (34, 35, 36) communicating with the oil return passage (34, 35, 36). 2. A gas pipe on the suction side to each compressor (21, 22, 23).
(19Gs), the base pipe (31, 31a, 31b), the suction pipe (21s, 22s, 23s) of each compressor (21, 22, 23) branching off from the base pipe (31, 31a, 31b)
Branch pipes (32a, 32b, 32c, 32d) communicating with the suction pipe (21s, 22s, 32d) through the branch pipes (32a, 32b, 32c, 32d). 23s), and each branch pipe (32a, 32b, 32c, 32d) joins at least the oil return passage (34, 35, 36) from the junction with the base pipe (31, 31a, 31b). The refrigeration system according to claim 1, further comprising an inclined portion (32i) inclined upward to a point. 3. The inclining portion (32i) includes at least a compression mechanism.
Branch pipe to compressors (22, 23) stopped during capacity control in (11)
The refrigeration apparatus according to claim 2, wherein the refrigeration apparatus is provided at (32b, 32d). 4. The compression mechanism (11) is a first compressor having a variable capacity.
(21) and a constant capacity second compressor (22), between the oil reservoir (21o) of the first compressor (21) and the suction pipe (22s) of the second compressor (22). And the oil reservoir (22) of the second compressor (22).
An oil return passage (34, 35) is provided between each o) and the suction pipe (21s) of the first compressor (21).
The refrigeration apparatus according to any one of the above. 5. The compression mechanism (11) is a first compressor having a variable capacity.
(21), a fixed capacity second compressor (22), and a fixed capacity third compressor (23). The oil sump (21o) of the first compressor (21) and the second compressor Between the suction pipe (22s) of the compressor (22) and the oil sump (22) of the second compressor (22).
o) and the suction pipe (23s) of the third compressor (23), the oil sump (23o) of the third compressor (23) and the suction pipe (2) of the first compressor (21).
The refrigeration system according to any one of claims 1 to 3, wherein an oil return passage (34, 35, 36) is provided between each of the refrigeration systems (1s). 6. A pressure reducing mechanism (41, 35) is provided in each oil return passage (34, 35, 36).
The refrigeration apparatus according to any one of claims 1 to 5, further comprising (43, 44a, 44b). 7. The refrigeration apparatus according to claim 6, wherein the pressure reducing mechanism is constituted by a capillary tube (41). 8. Each of the oil return passages (34, 35) is provided with a first passage (34).
a, 35a) and the first passage (34a, 35a).
s, 22s) and a second passage (34b, 35b) branched to the side, and the pressure reducing mechanism comprises a first passage (34a, 35a) and a second passage (34b, 35b).
The electromagnetic valve (43) and the capillary tube (41) provided on one of the sides (34a, 35a), and the capillary tube (41) provided on the other side (34b, 35b). Refrigeration equipment. 9. The refrigerating apparatus according to claim 6, wherein the pressure reducing mechanism comprises an electronic expansion valve (44a, 44b). 10. A plurality of high pressure dome type compressors (21, 22).
Is a refrigerating apparatus including a compression mechanism (11) connected in parallel, wherein the compression mechanism (11) includes a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity. Between the oil sump (21o) of the first compressor (21) and the suction pipe (22s) of the second compressor (22), and the oil sump (22) of the second compressor (22).
o) and the suction pipe (21s) of the first compressor (21) are provided with oil return passages (34, 35) having pressure reducing mechanisms (41, 43), respectively. ) Is the first passage (34a, 35a) and the first passage (34a, 35a).
A second passage (34b, 35b) branching from the intermediate point of the passage (34a, 35a) to the suction pipe (21s, 22s) side;
(41, 43) includes a first passage (34a, 35a) and a second passage (34b, 35b).
And a capillary tube (41) provided on one side (34a, 35a) and a capillary tube (41) provided on the other side (34b, 35b), and a compression mechanism (11). A refrigerating apparatus including a control unit (47) for closing each solenoid valve (43) when a compression ratio becomes higher than a predetermined value during operation. 11. A plurality of high pressure dome type compressors (21, 22).
Is a refrigerating apparatus including a compression mechanism (11) connected in parallel, wherein the compression mechanism (11) includes a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity. Between the oil sump (21o) of the first compressor (21) and the suction pipe (22s) of the second compressor (22), and the oil sump (22) of the second compressor (22).
o) and the suction pipe (21s) of the first compressor (21) are provided with oil return passages (34, 35) having electronic expansion valves (44a, 44b), respectively. )), When the compression ratio becomes higher than a predetermined value, the opening degree of the electronic expansion valves (44a, 44b) is reduced,
During operation of the compressor (21) alone, the compression ratio is lower than a predetermined value with the electronic expansion valve (44b) communicating with the oil reservoir (22o) of the second compressor (22) set to fully closed. When it gets higher, the first compressor (2
A refrigeration system including control means (47) for reducing the opening degree of the electronic expansion valve (44a) communicating with the oil reservoir (21o) of (1).