JP2001324231A - Refrigerating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lowering of performance, while avoiding complication of an oil equalizing structure, in a refrigerating apparatus using a plurality of compressors (21, 22) of a high-pressure dome type. SOLUTION: An oil equalizing passage (34) making the respective oil collecting parts (21o, 22o) of the compressors (21, 22) communicate with each other and an oil return passage (35) connected to the oil collecting part (21o) of a first compressor (21) and a suction pipe (22s) of a second compressor (22), are provided. The oil equalizing passage (34) is constituted as a one-way passage allowing refrigerating machine oil to flow only in the direction from the second compressor (22) to the first compressor (21), while the oil return passage (35) is provided with a pressure reducing mechanism (41).

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.

On the other hand, in order to simplify the structure,
For example, the oil sump of the second compressor (22) and the first compressor (21)
Between the suction side of the first compressor (21) and the oil reservoir of the first compressor (21) and the suction side of the second compressor (22) via a pressure reducing mechanism such as a capillary tube. It is conceivable that the refrigerating machine oil of one compressor (21, 22) is recovered to the other compressor (22, 21). However, in such a case, when both compressors (21, 22) are operating, a short circuit of the refrigerant occurs between the compressors (21, 22), and the performance is reduced. There is a risk.

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. Therefore, it is possible to prevent performance degradation while avoiding the problem.

[0009]

According to the present invention, when a plurality of compressors are operated, surplus refrigerating machine oil is returned to each of the compressors in order, and when only one compressor is operated, surplus refrigerating machine oil is recirculated. This is to return to the compressor.

[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 (21) of each compressor (21, 22, 23)
o, 22o, 23o) in order.
(34, 34a, 34b) and the oil sump (21o, 22o, 23o) of the compressor (21) connected to the downstream end by the oil equalizing passage (34, 34a, 34b) and the upstream end. Compressor (22,23) suction pipe (22s, 23s)
And an oil return passage (35) connected thereto.

The inlet of the oil equalizing passage (34, 34a, 34b) and the inlet of the oil return passage (35) are connected to, for example, the compressors (21, 22, 23).
And open downward to the oil sump (21o, 22o, 23o), and the outlet of the oil equalizing passage (34, 34a, 34b) in each compressor (21, 22, 23). It is good to constitute so that it may open upward. However, each passage (34, 24) in each compressor (21, 22, 23)
34a, 34b, 35) The direction of the inlet and outlet is not limited to this, as long as a predetermined oil level can be secured, upward, downward,
It may be arbitrarily selected from a horizontal orientation or the like.

[0012] A second solution taken by the present invention is:
In the first solution, the compression mechanism (11) is connected to a compressor (21) connected to the downstream end of the oil equalizing passage (34, 34a, 34b) from a compressor (22, 23) connected to the upstream end. ), The stop order during capacity control is determined to be higher.

[0013] A third solution taken by the present invention is:
The compression mechanism (11) is specified in the second solving means, and the compressor (2
2, 23) are set so that the high-pressure compressor (21) has a high pressure when a plurality of compressors are operated.

A fourth solution taken by the present invention is:
In the third solution, the compressors (22, 2) except for the compressor (21) connected to the downstream end by the oil equalizing passages (34, 34a, 34b).
The discharge pipe (22d, 23d) of (3) is provided with a check valve for preventing the backflow of the refrigerant, so that a difference occurs between the high pressures of the compressors (21, 22, 23).

[0015] The fifth solution taken by the present invention is:
In any one of the first to fourth solving means, a check valve (36) is provided in the oil equalizing passages (34, 34a, 34b).

[0016] A sixth solution taken by the present invention is:
In any one of the first to fifth solutions, the gas pipe (19Gs) on the suction side to each compressor (21, 22, 23) is connected to the base pipe (3
1) and branch pipes (32a, 32b, 32c) branching from the base pipe (31) and communicating with suction pipes (21s, 22s, 23s) of the compressors (21, 22, 23). The oil return passage (35) is connected to the suction pipes (22s, 23s) via branch pipes (32b, 32c), and each branch pipe (3
2a, 32b, 32c) are provided with an inclined portion (32i) which is inclined upward from a junction with the base pipe (31).

Further, a seventh solution taken by the present invention is:
In the sixth aspect of the present invention, the inclined portion (32i) is provided at least in a branch pipe (32b, 32c) to the compressor (22, 23) having a higher stopping order when controlling the capacity of the compression mechanism (11). It is like that.

An eighth solution taken by the present invention is:
In any one of the first to seventh solving means, the compression mechanism (11) includes a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity, Equalizing oil passage (34)
The refrigerating machine oil is allowed to flow only in the direction from the compressor (22) to the first compressor (21), and the oil return passage (35) is connected to the oil sump of the first compressor (21). Part (21o),
This is connected to the suction pipe (22s) of the second compressor (22o).

A ninth solution means adopted by the present invention is:
In any one of the first to seventh solving means, the compression mechanism (11) may include a variable capacity first compressor (21), a constant capacity second compressor (22), and a constant capacity second compressor. And the three compressors (23), and the oil equalizing passages (34a, 34b) are provided from the second compressor (22) to the first
A first oil equalizing passageway (34a) that allows the refrigerating machine oil to flow only in the direction toward the compressor (21), and refrigeration only in the direction from the third compressor (23) to the second compressor (22). A second oil equalizing passage (34b) for permitting the flow of machine oil, and an oil return passage (35) formed between the oil sump (21o) of the first compressor (21) and the third compressor (23). ) Is connected to the suction pipe (23s).

According to a tenth aspect of the present invention, in the first aspect, the oil return passage (35) is provided with a pressure reducing mechanism (41, 43, 44). It is like that.

According to an eleventh aspect of the present invention, in the tenth aspect, the pressure reducing mechanism is constituted by a capillary tube (41).

According to a twelfth aspect of the present invention, there is provided the oil return passage (35) according to the tenth aspect.
Is provided with a first passage (35a) and a second passage (35b) branched from an intermediate point of the first passage (35a) to the suction pipe (22s) side. Solenoid valve (43) and capillary tube (4) provided in one of the second passage (35b) and the second passage (35b).
1) and a capillary tube (41) provided on the other side.

According to a thirteenth aspect of the present invention, in the above tenth aspect, the pressure reducing mechanism is constituted by an electronic expansion valve (44).

Further, a fourteenth 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, which communicates the oil reservoirs (21o, 22o) of the compressors (21, 22) with each other and a second compressor (22). Oil passage (34) that permits the refrigerating machine oil to flow only in the direction from the first compressor (21) to the first compressor (21), the oil sump (21o) of the first compressor (21) and the second compressor (22). ) Is provided with an oil return passage (35) connected to the suction pipe (22s) via a pressure reducing mechanism (41, 43). Also, oil return passage (35)
With a first passage (35a) and a second passage (35b) branched from an intermediate point of the first passage (35a) to the suction pipe (22s) side, and a pressure reducing mechanism (41, 43). ) To the first passage (35a).
And a solenoid valve (43) provided in one (35b) of the second passages (35b).
And a capillary tube (41) provided on the other side (35a), and a solenoid valve (43) when the compression ratio becomes higher than a predetermined value during operation of the compression mechanism (11). ) Is provided with control means (47).

The fifteenth solution taken by the present invention is based on the premise that a refrigerating apparatus is provided with a compression mechanism (11) composed of a plurality of high-pressure dome type compressors (21, 22). And
The compression mechanism (11) is composed of a first compressor (21) having a variable capacity and a second compressor (22) having a constant capacity, and an oil reservoir (21o, 21o) of each compressor (21, 22). 22o) an oil equalizing passageway (34) communicating with each other and permitting the refrigerating machine oil to flow only in a direction from the second compressor (22) to the first compressor (21); and a first compressor (21). An oil return passage (35) connected via an electronic expansion valve (44) to the oil sump (21o) of the second compressor (22) and the suction pipe (22s) of the second compressor (22) is provided. A control means (47) for setting the opening of the electronic expansion valve (44) to a small value when the compression ratio becomes higher than a predetermined value during the operation of 11) is provided.

According to a sixteenth aspect of the present invention, in the fifteenth aspect, the opening degree of the electronic expansion valve (44) is set to be greater than that of the first compressor (21). The control means (47) is configured so as to be set to a small value during the operation of only). During operation of only the first compressor (21), the electronic expansion valve (44) may be fully closed in some cases.

-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, in the case where both compressors are operated using two compressors (21, 22), surplus oil is transferred from the compressor (22) on the upstream side of the oil equalizing passage (34) to the compressor (21) on the downstream side. Refrigerant and refrigerating machine oil flows, and the surplus refrigerating machine oil of the downstream compressor (21) is recovered together with the refrigerant to the upstream compressor (22) via the suction pipe (22s).

In the case of operating only one compressor (21), operating the compressor (21) at the downstream end in the second solving means causes the refrigerating machine oil to have a high pressure inside the compressor (21). This causes the oil to return to the oil return passage (35) together with the refrigerant. Since the compressors (21, 22) are connected in parallel, the refrigerating machine oil flows from the suction pipe (22s) of the compressor (22) on the stop side to the suction pipe of the compressor (21) on the operation side. It is sucked again by the compressor (21) through (21s) and collected.

In each of the above solutions, the oil equalizing passage (34)
Is a one-way passage. Therefore, in both cases of operating both compressors and only one of them, the upstream from the downstream compressor (21) through the oil equalizing passage (34) is used. Side compressor (2
2,23), there is no backflow of refrigerant and refrigerating machine oil. Therefore, generation of a short circuit of the refrigerant can be suppressed.

Further, in the third and fourth solving means, the compressors (22, 23) having a higher stop order during capacity control are set to a higher pressure than a lower compressor (21) during operation of a plurality of compressors. It is set to be. Therefore, the flow direction of the refrigerating machine oil and the refrigerant passing through the oil equalizing passage (34) during the operation of the plurality of units follows the flow direction of the oil equalizing passage.

In the fifth solution, the oil equalizing passage is provided.
Since the check valve (36) is provided at (34, 34a, 34b) to determine the flow direction of the refrigerating machine oil, the operation of each of the above-mentioned solving means can be reliably performed with a simple structure.

In the sixth solution, the branch pipes (32a, 32b, 32c) of the suction-side gas pipe (19Gs) are inclined upward from the junction with the base pipe (31). . Conversely,
The branch pipes (32a, 32b, 32c) are inclined downward to a junction with the base pipe (31). For this reason, the refrigerant containing the refrigerating machine oil flows from the operating compressor (21) to the oil return passage (3).
5) and compressor (22,23) stopped through branch pipe (32b, 32c)
And flows along the inclined portion (32i) toward the junction with the base pipe (31) before being collected by the operating compressor.

In the seventh solution, the inclined portion (3
2i) is provided at least in the branch pipes (32a, 32b) to the compressors (22, 23) having a higher stopping order when controlling the capacity of the compression mechanism (11). Is performed reliably.

[0034] In the eighth 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 solving means is reliably performed. According to the ninth solving 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 tenth to thirteenth solutions, the pressure reducing mechanism (41, 43, 44) constituted by the capillary tube (41) and the electronic expansion valve (44) is provided in the oil return passage (35). Therefore, the refrigerating machine oil can be collected in each of the compressors (21, 22, 23) while suppressing the flow rate in the oil return passage (35).

In the twelfth solution, the oil return passage (35) is composed of the first passage (35a) and the second passage (35b), and the first passage (35a) and the second passage (35). 35b) is a solenoid valve
It can be closed at (43). Therefore, as in the fourteenth 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, and when the compression ratio is low, the oil return amount 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.

In the thirteenth solution, the flow rate in the oil return passage (35) can be controlled by the electronic expansion valve (44). Therefore, as in the fifteenth solution, a plurality of high pressure dome type compressors (21, 22) are used as a variable capacity first compressor (21) and a constant capacity second compressor (22). , Each compressor
(21, 22) oil sump portions (21o, 22o) communicating with each other and permitting the refrigerating machine oil to flow only in the direction from the second compressor (22) to the first compressor (21). (34), an oil sump (21o) of the first compressor (21) and a suction pipe of the second compressor (22).
(22s) and an oil return passage (35) connected via an electronic expansion valve (44), the opening of the electronic expansion valve (44) is reduced when the compression ratio becomes higher than a predetermined value. By setting, an appropriate amount of refrigerating machine oil can be collected in each compressor, and the return of the refrigerant does not become excessive.

In particular, in the sixteenth solution,
The opening degree of the electronic expansion valve (44) is adjusted so that the opening degree of the electronic expansion valve (44) is different between when both compressors (21, 22) are operating and when only the first compressor (21) is operating. Operation is performed appropriately.

[0039]

According to the above-mentioned first to fifth means, a decrease in performance due to a short circuit of the refrigerant can be suppressed while preventing the structure from becoming complicated.

According to the second solution, the stop order of the compressors (21, 22, 23) during capacity control is set, so that a plurality of compressors (21, 22, 23) are provided. Driving and 1
In any of the cases where only the stand is operated, a decrease in performance can be reliably prevented.

Further, according to the third solution, a pressure difference is applied to each of the compressors (21, 22, 23) when a plurality of compressors are operated, so that the flows of the refrigerating machine oil and the refrigerant are equalized in the oil passage. (34) is reliably followed in the distribution direction, and the operation of each of the above solutions can be performed reliably.

According to the fourth solution, the operation of the third solution can be realized with a simple configuration.

According to the fifth solution, a check valve (36) is provided in the oil equalizing passages (34, 34a, 34b) to provide the oil equalizing passages (34, 34a, 34b).
Since the one-way passages 34a, 34b) are used, the structure can be prevented from becoming complicated.

According to the sixth and seventh solutions, when only one compressor (21) is operated, the refrigerant containing the refrigerating machine oil is supplied to the compressor (22, 23) which is stopped. Instead, it flows from the branch pipes (32b, 32c) to the junction with the base pipe (31) and is collected by the operating compressor (21). Therefore, it is possible to prevent the shortage of the refrigerating machine oil in the compressor (21) during operation, and to prevent the refrigerant and the refrigerating machine oil from returning to the stop-side compressor (22, 23), thereby preventing the occurrence of liquid compression upon restart. it can.

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

Further, according to the tenth to thirteenth means, 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), By suppressing the return amount of the above, a decrease in performance can be suppressed. According to the eleventh solution, the structure can be simplified because the capillary tube (41) is used for the pressure reducing mechanism.

According to the twelfth solution, since the capillary tube (41) and the solenoid valve (43) are used in combination, the flow rate is adjusted in accordance with the compression ratio so that the refrigerating machine oil can be used. While the collecting operation is surely performed, the complexity of the configuration can be suppressed. Further, according to the fourteenth solution, the compression mechanism (11) is provided with a variable capacity first compressor (21).
And the second compressor (22) having a constant capacity, the device can be put into practical use including the specific control of the solenoid valve (43) of the oil return passage (35).

In the thirteenth solution, the flow rate in the oil return passage (35) can be adjusted in a manner corresponding to the compression ratio by using the electronic expansion valve (43) for the pressure reducing mechanism. According to the fifteenth and sixteenth means, the compression mechanism (11) is provided with a variable capacity first compressor (21) and a constant capacity second compressor.
When it is configured with the compressor (22), the device can be put to practical use in a form that includes specific control of the electronic expansion valve (44) of the oil return passage (35).

[0049]

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. Then, the suction-side gas pipe (19Gs) from the accumulator (18) branches from the base pipe (31) to the branch pipes (32a, 32b), and the suction pipes (2, 22) of the compressors (21, 22).
1s, 22s) and the discharge pipe of each compressor (21, 22)
(21d, 22d) merge and are 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. By providing the check valve (33) in the discharge pipe (22d) of the second compressor (22) in this way, the second compressor (22) can be operated while both compressors (21, 22) are operating. Has a slightly higher pressure.

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. .
That is, the compression mechanism (11) controls the second compressor (22) during capacity control.
Of the first compressor is set higher than the first compressor. Also, when more than a predetermined capacity is required,
In a state where the second compressor (22) is also started, the first compressor (21)
Are 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.

<Recovery structure of refrigerating machine oil> Each compressor (21, 22)
Has an oil reservoir (21o, 22o) for storing refrigeration oil in a high pressure portion inside the compressor (21, 22). The oil sump passage (34) communicating the oil sump portions (21o, 22o) of the compressors (21, 22) with each other, the oil sump portion (21o) of the first compressor (21) and the second compressor An oil return passage (35) connected to the branch pipe (32b) on the (22) side is provided.

More specifically, the oil equalizing passage (34) allows the refrigerating machine oil (and the refrigerant) to flow only in the direction from the second compressor (22) to the first compressor (21). , Check valve (36)
And is configured as a one-way passage having The oil return passage (35) has a capillary tube as a pressure reducing mechanism.
(41) is provided.

The inlet of the oil equalizing passage (34) and the inlet of the oil return passage (35) are connected to the oil sump (21o, 22o) in each compressor (21, 22).
Is configured to open downward toward the oil equalizing passage
The outlet of (34) is configured to open upward in the compressor (21).

As described above, the oil equalizing passage (34) and the oil returning passage (35)
When both compressors (21, 22) are operated, the refrigerating machine oil and the refrigerant flow through the respective compressors (21, 22) through the respective passages (34, 35) in order to form a loop. While operating only the first compressor (21), the first compressor (2
The refrigerating machine oil and the refrigerant in 1) return to the first compressor (21) through the oil return passage (35).

Although not shown, the discharge-side gas pipe
In (19Gd), an oil separator is provided at the part where the discharge pipes (21d, 22d) of each compressor (21, 22) merge, so that the refrigerating machine oil is separated from the refrigerant and returned to the accumulator (18). Is also good.

-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.

While controlling the capacity of the compression mechanism (11) as described above, 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 is used 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 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 refrigerant is supplied to 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 that has flowed out of the indoor heat exchanger (17) in the operating indoor unit (2) passes through the indoor expansion valve (16) that is set to be fully open, and is sent 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. Here, when both compressors (21, 22) are operated,
The pressure loss on the discharge side of the second compressor (22) is larger than that on the discharge side of the first compressor (21) by the amount of the check valve (33). Therefore, the discharge side of the first compressor (21) and the second compressor (2
A pressure difference is generated between the discharge side of 2) and the pressure of the second compressor (22) is slightly higher than that of the first compressor (21). Therefore,
The surplus of the refrigerating machine oil on the second compressor (22) side flows to the first compressor (21) through the oil equalizing passage (34) together with the refrigerant, and
When there is surplus refrigeration oil in the compressor (21), the refrigeration oil is pushed out of the oil return passage (35) together with the refrigerant. Then, the refrigerating machine oil and the refrigerant flowing out of the oil return passageway (35) merge with the suctioned refrigerant on the second compressor (22) side, and the second compressor (2
Collected in 2).

[0069] In this case, when the refrigerating machine oil tends to accumulate in the first compressor (21), it is recovered by the second compressor (22) and tends to accumulate in the second compressor (22). To the first compressor (21), so that one of the compressors (21, 22)
The amount of refrigerating machine oil in each of the compressors (21, 22) is made uniform without accumulating or running out of refrigerating machine oil.

When only one first compressor (21) is operated, if the refrigerating machine oil is accumulated at a predetermined level or higher, the oil return path (along with the refrigerant) due to the high pressure in the first compressor (21). 35). Then, the refrigerant and the refrigerating machine oil that have flowed out are sucked again by the first compressor (21) together with the gas refrigerant on the suction side and collected. At this time, a check valve is installed in the oil equalizing passage (34).
Since the (36) is provided, the refrigerating machine oil and the refrigerant do not flow from the first compressor (21) to the second compressor (22). From the above, accumulation of the refrigerating machine oil and the refrigerant in the stopped second compressor (22) is prevented.

Since the oil return passage (35) is provided with a capillary tube (41) as a pressure reducing mechanism, each of the compressors is controlled while the flow rates of the refrigerant and the refrigerating machine oil in the oil return passage (35) are suppressed appropriately. Refrigeration oil is collected at (21,22).

-Effects of First Embodiment- According to the first embodiment, the first compressor (21) and the second compressor (2
The oil sump portions (21o, 22o) of (2) are communicated with each other by an oil leveling passage (34), and the oil sump portion (21o) of the first compressor (21) and the second compressor (2
When both compressors (21,22) are operated by communicating the suction pipe (22s) of (2) with the oil return passage (35), they are collected by each compressor (21,22). The amount of refrigerating machine oil is made uniform. Also, when operating only one first compressor (21),
In the first compressor (21), the refrigerating machine oil flows out of the oil return passage (35) together with the refrigerant due to the high pressure in the first compressor (21), and is again sucked into the first compressor (35) and collected. Is done. Therefore, it is possible to prevent liquid compression from occurring when the second compressor (22) is restarted.

As described above, according to the first embodiment, while the structure is simplified, it is possible to prevent the occurrence of problems such as excessive or insufficient refrigerating machine oil on one of the compressors (21, 22). it can. In addition, the capillary tube (4
Since 1) is used, it is possible to prevent a decrease in the performance due to the short circuit of the refrigerant by suppressing an increase in the flow rate of the refrigerant in the oil return passage (35) while simplifying the structure.

[0074]

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 (19Gs) on the suction side to the compressors (21, 22)
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 passage (35).
FIG. 3 shows branch pipes (32a, 32b) to both compressors (21, 22).
Although the example in which the inclined portion (32i) is provided in the
i) 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) shows an external view in which an oil return passage (35) is connected. As shown, the base pipe of the suction side gas pipe (19Gs)
(31) is connected to branch pipes (32a, 32b) to the compressors (21, 22) via a Y-shaped pipe joint (42). The first compressor is mounted on the inclined portion (32i) of the branch pipe (32b) leading to the second compressor (22).
The oil return passage (35) from (21) is connected.

-Operating Operation- Also in the second embodiment, the circulation operation of the refrigerant 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 compressors (21, 22) are operated, the excess refrigerating machine oil on the second compressor (22) side flows through the oil equalizing passage (34) together with the refrigerant in the same manner as in the first embodiment. The refrigerant flows and is collected by the first compressor (21), and the excess refrigerating machine oil on the first compressor (21) side is pushed out together with the refrigerant into the oil return passage (35), and is sucked into the second compressor (22). Collected. 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, if the refrigerating machine oil accumulates at a predetermined level or more in the first compressor (21), the refrigerating machine oil is removed from the first compressor (21). The refrigerant and the refrigerating machine oil which have flowed out of the oil return passage (35) together with the refrigerant due to the high pressure inside, are sucked again by the first compressor (21) and collected. In the second embodiment, the suction-side gas pipe
Since the (19Gs) branch pipes (32a, 32b) are inclined upward from the junction with the base pipe (31) to at least the junction with the oil return passage (35), the branch pipe (32b) Conversely, it is inclined downward from the junction with the oil return passage (35) to the junction with the base pipe (31). Therefore, the first compressor (21)
Since the refrigerant and the refrigerating machine oil flowing out of the compressor flow downward along the slope, they do not flow toward the stopped second compressor (22),
After flowing toward the junction with the base pipe (31), it is reliably collected by the operating first compressor (21).

-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). It is possible to reliably prevent liquid compression from occurring at the time of restart. In addition, it is possible to prevent the shortage of refrigerating machine oil in the first compressor (21) during operation.

[0082]

Third Embodiment As shown in FIG. 5, a third embodiment of the present invention has a configuration in which an oil return passage (35) is different from the above embodiments.

Specifically, the oil return passage (35) is connected to the first passage (3
5a) and a second passage (35b) branched from the intermediate point of the first passage (35a) to the suction pipe (22s) side. The decompression mechanism includes a capillary tube (41) provided in the first passage (35a), a capillary tube (41) provided in the second passage (35b), and a solenoid valve (43).

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- In the third embodiment as well, 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 high pressure, the solenoid valve (43) of the second passage (35b) is closed, and the compression ratio is reduced. When it is lower than the predetermined value, the solenoid valve (43) is opened.

With the above configuration, in the configuration of the first embodiment, depending on the degree of pressure reduction 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 refrigerating machine oil is easily returned by using the two passages (35a, 35b) when the compression ratio is low, and the refrigerant is easily returned when the compression ratio is high. One passage (35
Using only a) can prevent the refrigerating machine oil and 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 the Third Embodiment- According to the third embodiment, the refrigerating machine oil can be easily returned at a low compression ratio, so that the reliability of the mechanism can be improved. Since it is possible to prevent the refrigerating machine oil and the refrigerant from returning excessively, it is possible to suppress a decrease in performance.

[0091]

Embodiment 4 As shown in FIG. 6, Embodiment 4 of the present invention has a configuration in which an oil return passage (35) is different from the above embodiments.

Specifically, the oil return passage (35) has a configuration in which the capillary tube (41) is provided as a pressure reducing mechanism in the first embodiment, whereas the oil return passage (35) has a capillary tube as the pressure reducing mechanism in the fourth embodiment. An electronic expansion valve (44) is used instead of (41).

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 valve (44). The controller (47) is configured to decrease the opening of the electronic expansion valve (47) when the compression ratio becomes higher than a predetermined value. In addition, comparing the operation of both compressors (21, 22) with the operation of only the first compressor (21), the electronic expansion valve (44) is in a state in which the single electronic expansion valve (44) is more narrowed in operation. (In some cases, fully closed) to reduce the loss of refrigerant.

-Operational Operation- In the fourth embodiment as well, 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 recovering 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.

In the case where the determination in step ST4 is performed, both compressors
(21, 22) is in operation. If it is determined that the compression ratio is high (the compression ratio is higher than a predetermined value) under these conditions, the opening of the electronic expansion valve (shown as EV in the figure) (44) is lowered in step ST6. The refrigeration oil and the refrigerant are made more difficult to flow through the oil return passage (35) than at the compression ratio. If it is determined in step ST4 that the compression ratio is lower than the predetermined value, the process proceeds to step ST7.
In this case, the electronic expansion valve (44) is opened more than at the time of the high compression ratio, so that the refrigerating machine oil can easily flow through the oil return passage (35) so that the oil can be reliably collected. In this flowchart, N2pls and N1pls represent the degree of opening of the electronic expansion valve (44), and N2pls represents a state where the electronic expansion valve (44) is narrowed down more than N1pls.

On the other hand, when performing the determination in step ST5,
Only the first compressor (21) is operating. Again,
If it is determined that the compression ratio is high, the electronic expansion valve (44) is narrowed down in step ST8 as compared with the low compression ratio. If it is determined that the compression ratio is low, in step ST9 the electronic expansion valve is reduced.
Open (44) more than at high compression ratios. In this case, the setting of the opening degree of the electronic expansion valve (44) in steps ST8 and ST9 is N2 'compared to the setting of the opening degree in steps ST6 and ST7.
pls and N1'pls are performed so as to be narrower than N2pls and N1pls, respectively, and in some cases, they are fully closed.

-Effects of 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, since the electronic expansion valve (44) is used in the fourth embodiment, if the degree of opening is adjusted more finely, the performance is reduced while increasing the reliability as compared with the third embodiment. Can be prevented. In addition, particularly when one vehicle is operating, a decrease in performance can be prevented by suppressing loss of the refrigerant.

[0101]

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) which are on / off controlled. It is configured. Then, the suction pipes (21S, 2S) of each compressor (21, 22, 23)
2S, 23S) are connected together, and the discharge pipes (21d, 22d, 23d) are connected together, and three compressors (21, 22, 23) are connected in parallel.

Specifically, the base pipe of the suction side gas pipe (19 Gs)
(31) branches into three branch pipes (32a, 32b, 32c), and the first branch pipe (32a) is connected to the first compressor (21). Also,
The second branch pipe (32b) is connected to the second compressor (22), and the third branch pipe (32c) is connected to the third compressor (23). The branch pipes (32a, 32b, 32c) to the compressors (21, 22, 23) are configured to incline upward from the junction with the base pipe (31).

On the other hand, regarding the discharge side, the first compressor (21)
The discharge pipe (21d) of the second compressor (22) merges with the discharge pipe (22d) of the second compressor (22) and is connected to the discharge-side gas pipe (19Gd).
Discharge pipe (23d) joins the discharge pipe (22d) of the second compressor (22). The discharge pipes (22d, 23d) of the second compressor (22) and the third compressor (23) have reverse pipes that allow only the outflow of the refrigerant from the second and third compressors (22, 23). A stop valve (33) is provided. By providing this check valve, three compressors
When operating (21,22,23), the first compressor (21)
The pressure is gradually increased toward the compressor (23).

The oil return passage (35) is connected to the first compressor (21).
Of the third compressor (23) and a branch pipe (32c) to the suction pipe (23s) of the third compressor (23). And equalizing oil passage
(34) is provided between the second compressor (22) and the first compressor (22) between an oil reservoir (21o) of the first compressor (21) and an oil reservoir (22o) of the second compressor (22). A first oil leveling passage (34a) connected via a check valve (36) allowing only the flow to the 21), an oil sump (22o) of the second compressor (22) and a third compressor (23) Oil pool (23o)
A second oil equalizing passage connected via a check valve (36) allowing only the flow from the third compressor (23) to the second compressor (22)
(34b).

FIG. 9 shows a branch pipe of the suction-side gas pipe (19 Gs).
(32a, 32b, 32c) and an external view in which an oil return passage (35) is connected. As shown in the figure, the base pipe (31) of the suction-side gas pipe (19Gs) branches into two via a Y-shaped pipe joint (42),
One branch pipe (32a) is connected to the suction side of the first compressor (21). The other branch pipe is a Y-type pipe joint (42).
The other branch pipe (32c) is connected to the suction side of the second compressor (22), and the other branch pipe (32c) is connected to the third branch pipe (32c).
It is connected to the suction side of the compressor (23). The first compressor is placed on the inclined portion (32i) of the branch pipe (32c) leading to the third compressor (23).
The oil return passage (35) from (21) is connected.

The compressors (21, 22, 23) are 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.

-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, as shown in FIG. 11, the refrigerant flows according to the solid arrows, and the refrigerating machine oil flows according to the broken arrows. That is, the refrigerant is branched from the base pipe (31) to the first branch pipe (32a), and is sucked into the first compressor (21). Then, it is compressed to a predetermined high pressure and flows out of the discharge pipe (21d), and flows through the discharge side gas pipe (19Gd) to the outdoor heat exchanger (13) or the indoor heat exchanger (17). The second compressor (22) and the third compressor (2
Since the check pipe (22d, 23d) of (3) is provided with a check valve (33), the refrigerant discharged from the first compressor (21) is supplied to the outdoor heat exchanger (13) or the indoor heat exchanger (17). It flows only to the) side.

Since the refrigerant discharged from the first compressor (21) contains refrigerating machine oil, the refrigerating machine oil also circulates in the refrigerant circuit (10). Then, when the refrigerating machine oil that has returned to the first compressor (21) exceeds a predetermined level in the oil sump (21o), it is pushed out of the oil return passage (35) together with the refrigerant and flows out.
The spilled refrigerant and refrigerating machine oil are transferred to the branch pipe (3) to the third compressor (23).
2c), flows downward along the inclined portion (32i) of the branch pipe (32c), is mixed with the gas refrigerant on the suction side, and is sucked into the first compressor (21). Therefore, the first compressor (2
The refrigerating machine oil in 1) does not flow to the second compressor (22) or the third compressor (23), and the refrigerating machine oil of the first compressor (21) is maintained at a predetermined level.

Next, when operating the first compressor (21) and the second compressor (22), as shown in FIG.
1) into the first branch pipe (32a) and the second branch pipe (32b), and the suction pipes (21s, 22) of the first compressor (21) and the second compressor (22).
s) and is sucked into the first and second compressors (21, 22).
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). The discharge pipe (23d) of the third compressor (23) is provided with a check valve (33).
No backflow of the refrigerant from (23d) to the third compressor (23) occurs.

When the refrigerating machine oil in the second compressor (22) exceeds a predetermined level, it flows through the oil equalizing passage (34a) together with the refrigerant due to the differential pressure of each compressor (21, 22). It flows to the compressor (21). Further, when the refrigerating machine oil in the first compressor (21) exceeds a predetermined level, the refrigerating machine oil is pushed out together with the refrigerant from the oil return passage (35) and flows out. The spilled refrigerating machine oil returns to the oil return passage.
(35) and the branch pipe (32c) to the third compressor (23) from the junction, along the inclined part (32i) of the branch pipe (32c), the second branch pipe (32).
b), merges with the suction refrigerant, and is sucked into the second compressor (22).

As described above, when 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. It does not flow to the compressor (23) but is collected by the operating first and second compressors (21) and (22) to a predetermined level in the first and second compressors (21, 22). Is maintained.

Next, when all three compressors (21, 22, 23) are operated, as shown in FIG. 13, the refrigerant flows from the base pipe (31) to each of the branch pipes (32a, 32b, 32c). To each compressor (21,22,2
3) through the suction pipes (21s, 22s, 23s)
Inhaled at 2,23). 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 joins the refrigerant circuit (1).
Cycle 0). At this time, the refrigerating machine oil circulates through the refrigerant circuit (10) while being contained in the refrigerant.

In this case, when the refrigerating machine oil in the third compressor (23) exceeds a predetermined level, the refrigerating machine oil passes through the second oil equalizing passage (34b) together with the refrigerant due to the differential pressure of each compressor (22, 23). Compressor (2
Flow to 2). When the refrigerating machine oil in the second compressor (22) exceeds a predetermined level, the first compressor (21) passes through the oil equalizing passage (34a) together with the refrigerant due to the differential pressure of the compressors (21, 22). ). Further, when the refrigerating machine oil in the first compressor (21) exceeds a predetermined level, it is pushed out together with the refrigerant from the oil return passage (35) and flows out. The spilled refrigerating machine oil passes through the oil return passage (3
At the junction of 5) and the branch pipe (32c) to the third compressor (23), the refrigerant merges with the suction refrigerant and is sucked into the third compressor (23).

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, The oil equalizing passages (34a, 34b) are provided between the first compressor (21) and the oil return passage (32c) from the oil reservoir (21o) of the first compressor (21) to the third compressor (23). By merely providing 35), the refrigerating machine oil in each of the compressors (21, 22, 23) can be maintained at a predetermined level. Therefore, it is possible to prevent a problem that the compressor oil is insufficient or excessive in one compressor (21, 22, 23), while avoiding complication of the configuration.

[0119]

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 not limited to a refrigerating apparatus in which the compression mechanism (11) is composed of a plurality of high-pressure dome compressors. For example, the present invention can be applied.

Further, the pressure reducing mechanism (41, 43) (44) having the structure shown in Embodiments 3 and 4 is replaced with the oil return passage of the compression mechanism (11) of Embodiment 2 in which the branch pipes (32a, 32b) are inclined. (35), or may be provided in the oil return passage (35) of the compression mechanism (11) of the fifth embodiment.

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

In the above embodiments, the oil equalizing passages (34,
34a, 34b) and the oil return passage (35) so as to open downward toward the oil sump (21o, 22o, 23o) in each compressor (21, 22, 23). Configure and equalize oil passages (34,34a, 34b)
Is configured to open upward in each compressor (21, 22), but as long as a predetermined oil level can be secured,
The direction of the opening of the inlet and outlet of each passage (34, 34a, 34b, 35) in each compressor (21, 22, 23) may be arbitrarily selected from upward, downward, lateral, and the like. FIG. 14A shows an example in which the terminal is turned upward, and FIG. 14B shows an example in which the terminal is turned laterally.

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 passage (35) may be changed as shown in FIG. In this example, the inclined portion (32i) shown in FIG. 4 is not provided, and a branch pipe to the second compressor (22) is provided.
Oil return passage from the first compressor (21) in the vertical portion of (32b)
(35) is connected. For this reason, the refrigerating machine oil flowing out of the first compressor (21) does not flow to the second compressor (22) when only the first compressor (21) is operating, but is collected by the first compressor (21), During the operation of both compressors (21, 22), the refrigerant flows to the second compressor (22), and the refrigerating machine oil can be recovered in the same manner as in the example of FIG.

[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) Base pipe (31i) Inclined section (32a, 32b, 32c) Branch pipe (34,34a, 34b) Equalizing oil passage (35) Oil return passage (35a) 1st passage (35b) 2nd passage (41) Capillary tube (pressure reduction mechanism) (43) Solenoid valve (pressure reduction mechanism) (44) Electronic expansion valve (pressure reduction mechanism) (47) Controller (control means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H003 AA01 AC03 BD12 CC05 CD07 CE02 3H045 AA02 AA09 AA16 AA27 BA13 BA37 CA24 DA32 EA16 EA26 3H076 AA39 BB32 CC43 CC44 CC70 CC77 CC94 CC95 CC97

Claims (16)

[Claims] A plurality of high-pressure dome-type compressors (21, 22, 23)
Is a refrigerating apparatus provided with a compression mechanism (11) connected in parallel, and has a one-way passage that sequentially communicates the oil reservoirs (21o, 22o, 23o) of the compressors (21, 22, 23). A certain oil equalizing passage (34, 34a, 34b) and a compressor connected to the downstream end by the oil equalizing passage (34, 34a, 34b)
(21), an oil return passage (35) connected to the suction pipes (22s, 23s) of the compressors (22, 23) connected to the upstream end. Refrigeration equipment. 2. The compression mechanism (11) includes an oil equalizing passage (34, 34a, 34b).
The stop order during capacity control is determined to be higher in order from the compressor (21) connected to the downstream end of the compressor to the compressor (22, 23) connected to the upstream end. Refrigeration equipment. The compression mechanism (11) is configured such that a compressor (22, 23) having a higher stop order during capacity control is replaced by a compressor (21) having a lower stop order.
3. The refrigeration system according to claim 2, wherein the refrigeration system is set to have a high pressure when a plurality of units are operated. 4. The compression mechanism (11) includes an oil equalizing passage (34, 34a, 34b).
Compressor (22, except for the compressor (21) connected to the downstream end by
The refrigerating apparatus according to claim 3, wherein a check valve (33) for preventing backflow of the refrigerant is provided in the discharge pipe (22d, 23d) of (23). 5. The oil equalizing passage (34, 34a, 34b) is provided with a check valve (36) and is configured as a one-way passage.
The refrigeration apparatus according to any one of the above. 6. A gas pipe on the suction side to each compressor (21, 22, 23).
(19Gs) is a base pipe (31) and a branch pipe branched from the base pipe (31) and communicating with the suction pipes (21s, 22s, 23s) of the compressors (21, 22, 23).
(32a, 32b, 32c), and the oil return passage (35) is connected to the branch pipe (3
2b, 32c) to the suction pipes (22s, 23s), and each of the branch pipes (32a, 32b, 32c) has an inclined portion that is inclined upward from the junction with the base pipe (31). The refrigeration apparatus according to any one of claims 1 to 5, further comprising (32i). 7. The inclined portion (32i) includes at least a compression mechanism.
In the capacity control of (11), the compressor (22, 2
The refrigeration apparatus according to claim 6, which is provided in a branch pipe (32b, 32c) to 3). 8. The compression mechanism (11) is a variable capacity first compressor.
(21) and a second compressor (22) having a constant capacity. The equalizing oil passage (34) is configured to refrigerate only in a direction from the second compressor (22) to the first compressor (21). The oil return passage (35) is configured to allow the flow of machine oil, and the oil return passage (35) is provided with an oil sump (21o) of the first compressor (21).
The refrigeration apparatus according to any one of claims 1 to 7, wherein the refrigeration apparatus is connected to the suction pipe (22s) of the second compressor (22o). 9. The compression mechanism (11) is a first compressor having a variable capacity.
(21), a constant capacity second compressor (22), and a constant capacity third compressor (23), and the equalizing oil passages (34a, 34b) extend from the second compressor (22). 1st compressor
(21), a first oil equalizing passage (34a) allowing the circulation of the refrigerating machine oil only in the direction toward (21), and a second compressor (2) from the third compressor (23).
The second that allows the refrigerating machine oil to flow only in the direction toward 2)
An oil return passage (35), and an oil return passage (35).
The refrigeration apparatus according to any one of claims 1 to 7, wherein the refrigeration apparatus is connected to the suction pipe (23s) of the third compressor (23). 10. A pressure reducing mechanism (41, 43, 44) in an oil return passage (35).
The refrigeration apparatus according to any one of claims 1 to 9, further comprising: 11. The refrigeration apparatus according to claim 10, wherein the pressure reducing mechanism is constituted by a capillary tube (41). 12. The oil return passage (35) includes a first passage (35a) and a second passage (35b) branched from an intermediate point between the first passage (35a) and the suction pipe (22s). The pressure reducing mechanism includes an electromagnetic valve (43) and a capillary tube (41) provided in one of the first passage (35a) and the second passage (35b),
The refrigeration apparatus according to claim 10, which is constituted by a capillary tube (41) provided on the other side. 13. The refrigerating apparatus according to claim 10, wherein the pressure reducing mechanism comprises an electronic expansion valve (44). 14. 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. Refrigeration oil that communicates with the oil sump portions (21o, 22o) of the compressors (21, 22) and that moves only from the second compressor (22) to the first compressor (21). Equalizing oil passage (34)
And the oil sump (21o) of the first compressor (21) and the second compressor (2
An oil return passage (35) connected to the suction pipe (22s) of (2) via a pressure reducing mechanism (41, 43) is provided. The oil return passage (35) has a first passage (35a) and the first passage (35a). One passage (35a)
Second passage (35b) branched from the middle point of the pipe to the suction pipe (22s) side
And a pressure reducing mechanism (41, 43) is provided in the first passage (3).
5a) and a solenoid valve provided in one of the second passages (35b) (35b)
(43), a capillary tube (41), and a capillary tube (41) provided on the other side (35a) .If the compression ratio becomes higher than a predetermined value during operation of the compression mechanism (11), the solenoid valve A refrigeration system comprising control means (47) for closing (43). 15. A plurality of high pressure dome type compressors (21, 22).
A compression mechanism (11) comprising: a first compressor (21) having a variable capacity; and a second compressor (22) having a constant capacity. The oil reservoirs (21o, 22o) of the compressors (21, 22) communicate with each other and allow the refrigerating machine oil to flow only in the direction from the second compressor (22) to the first compressor (21). Equalizing oil passage (34)
And the oil sump (21o) of the first compressor (21) and the second compressor (2
An oil return passage (35) connected to the suction pipe (22s) of (2) via an electronic expansion valve (44), and the compression ratio is higher than a predetermined value during operation of the compression mechanism (11). Then, the control means (4) for setting the opening of the electronic expansion valve (44) small
7) has refrigeration equipment. 16. The control means (47) is configured to set the opening degree of the electronic expansion valve (44) smaller during operation of only the first compressor (21) than during operation of both compressors. Claim 15
A refrigeration device as described.