JP2003269812A - Compression mechanism of refrigeration system - Google Patents

Abstract

(57) [Problem] To improve the reliability of oil supply to each compressor in a compression mechanism in which a high-pressure dome type compressor and a low-pressure dome type compressor are provided in parallel with each other. One unit can be operated by one of the machines. SOLUTION: The compression mechanism 11 of the air conditioner 1 includes a first compressor 21 of a high pressure dome type, a second compressor 22 of a low pressure dome type, a refrigerant suction mother pipe 23, a first branch pipe 24,
Second branch pipe 25, first compressor 21 and second branch pipe 2
5 and an oil separator 27 for connecting
And an oil return pipe 28 connected to the first branch pipe 24. The first branch pipe 24 is formed so as to have a downward slope from a connection with the oil return pipe 28 to a connection with the refrigerant suction mother pipe 23. Second branch pipe 25
Is formed so as to have a downward slope from a connection with the oil discharge pipe 26 to a connection with the refrigerant suction mother pipe 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression mechanism of a refrigeration system, and more particularly to a compression mechanism used in a refrigerant compression type refrigeration system.

[0002]

2. Description of the Related Art As an example of a conventional refrigerating apparatus having a compression mechanism having a plurality of compressors, as shown in FIG. 3, one outdoor unit 102 and a plurality of indoor units connected in parallel with it. There is an air conditioner 101 that includes The outdoor unit 102 mainly includes a compression mechanism 111 that compresses a refrigerant gas.
And a four-way switching valve 112 and an outdoor heat exchanger 113. The indoor unit 103 mainly has an expansion valve 114 and an indoor heat exchanger 115.

As the compression mechanism 111 provided in the outdoor unit 102 of the air conditioner 101, there is one in which a high pressure dome type compressor and a low pressure dome type compressor are provided in parallel. Here, the high-pressure dome type compressor is a compressor in which an oil sump is provided on the discharge side (high pressure side). Further, the low-pressure dome type compressor is a compressor in which an oil sump is provided on the suction side (low-pressure side). In such a compression mechanism having a plurality of compressors, it is important to supply sufficient oil to each compressor, and a mechanism for supplying oil to each compressor has been conventionally proposed.

As a compression mechanism capable of ensuring the supply of oil to each compressor, there is a compression mechanism 111 disclosed in Japanese Patent Laid-Open No. 5-39962. In this compression mechanism 111, as shown in FIG. 4, a high-pressure dome type first compressor 121, a low-pressure dome type second compressor 122, and a refrigerant suction mother pipe 123.
And the first compressor 12 by being branched from the refrigerant suction mother pipe 123.
1, a first branch pipe 124 connected to the suction side, a second branch pipe 125 branched from the refrigerant suction mother pipe 123 and connected to the suction side of the second compressor 122, and each compressor 121,
An oil separator 127 connected to the discharge side of 122 for separating the oil in the refrigerant, and an oil separator 127 for returning the oil separated by the oil separator 127 to the first branch pipe 124 on the suction side of the first compressor 121. The oil return pipe 128 is provided. Here, both oil return pipes 128 of each oil separator 127 are connected to the suction side of the first compressor 121, and all the oil separated by the oil separator 127 is sucked into the first compressor 121. It is supposed to be done.

In this compression mechanism 111, when both the first and second compressors 121 and 122 are operated, the second compressor 122 has the refrigerant suction mother pipe 123 through the second branch pipe 12 connected thereto.
The oil is sucked together with the refrigerant circulating in the refrigerant circuit via 5, and the oil supplied from the oil return pipe 128 is sucked into the first compressor 121. In this way, the first compressor 1
The necessary amount of oil is supplied to the oil sump 121a of the No. 21 and the oil sump 122a of the second compressor 122.

[0006]

In such a compression mechanism, there is a demand that only one of the two compressors can be operated. However, in the above-described conventional compression mechanism 111, for example, when the first compressor 121 is stopped and only the second compressor 122 is operated,
Even though the compressor 121 is stopped, the oil return pipe 128 on the discharge side of the second compressor 122 is connected to the first compressor 1
There is a possibility that the flow for supplying the oil to the suction side of 21 remains generated, and the oil may not be sufficiently supplied to the second compressor 122. In addition, the second compressor 122 is stopped and the first compressor
If only the compressor 121 is operated, the second compressor 1
22 from the oil return pipe 128 on the discharge side to the first compressor 121.
There is a risk that oil will not be supplied to the suction side of the oil and that the oil will not be sufficiently supplied to the first compressor 121. in this way,
In the conventional compression mechanism 111, each compressor 121,
If one of the compressors 121, 12 is operated, the oil supply and demand balance in the compression mechanism 111 is lost.
Since it becomes impossible to secure the required amount of oil in No. 2, it is difficult to operate one unit.

Further, the first and second compressors 121, 122
Even when the two units are in operation, the oil in the second compressor 122 is supplied by the oil that circulates in the refrigerant circuit. Therefore, depending on the operating state of the air conditioning apparatus 101, a state in which the oil is not sufficiently supplied may occur. There is a fear. An object of the present invention is to provide a compression mechanism in which a high-pressure dome type compressor and a low-pressure dome type compressor are provided in parallel with each other, while improving reliability of oil supply to each compressor. One is to enable the operation of one unit.

[0008]

A compression mechanism of a refrigeration system according to claim 1 is a compression mechanism used in a refrigeration system of a refrigerant compression type, which is a high pressure dome type first compressor and a low pressure dome type. The second compressor, the refrigerant suction mother pipe, the first branch pipe, the second branch pipe, the oil discharge pipe, the oil separator, and the oil return pipe. The second compressor is connected in parallel with the first compressor. The first branch pipe branches from the refrigerant suction mother pipe and is connected to the suction side of the first compressor. The second branch pipe branches from the refrigerant suction mother pipe and is connected to the suction side of the second compressor. The oil discharge pipe connects the first compressor and the second branch pipe. The oil separator is connected to the discharge sides of the first compressor and the second compressor and separates oil from the refrigerant compressed by the first compressor and the second compressor. The oil return pipe connects the oil separator to one of the first branch pipe and the refrigerant suction mother pipe. The second branch pipe is configured so that, when operating only the second compressor, the oil returned from the oil return pipe to one of the first branch pipe and the refrigerant suction mother pipe is sucked into the second compressor. It is connected. Also, the oil discharge pipe is
It is connected so that the oil discharged from the first compressor to the second branch pipe is returned to the refrigerant suction mother pipe when only the first compressor is operated.

In the compression mechanism of this refrigeration system, the oil return pipe is connected to one of the first branch pipe and the refrigerant suction mother pipe so that the oil return pipe can be returned to the suction side of the high-pressure dome type first compressor. An oil discharge pipe for supplying oil from the first compressor to the second branch pipe is provided. With this configuration,
The hydraulic pressure of the first high-pressure dome type compressor is the second hydraulic pressure of the low-pressure dome type
Compressor oil pressure (ie pressure on the suction side of the second compressor)
Since the pressure is higher than that of the first compressor, oil can be supplied from the first compressor to the suction side of the second compressor.

As a result, in the compression mechanism of this refrigeration system, when the first and second compressors are simultaneously operated, the first compressor receives oil from the oil separator via the oil return pipe and the first branch pipe. Oil is supplied to the second compressor from the first compressor via the oil discharge pipe and the second branch pipe, and the reliability of the oil supply to the first and second compressors is improved. Has improved.

When only the first compressor is operated, the first
Since the oil supplied from the compressor to the oil discharge pipe and the second branch pipe is returned to the refrigerant suction mother pipe,
The compressor includes oil supplied from the oil return pipe via the first branch pipe, and oil returned from the first compressor to the refrigerant suction mother pipe via the oil discharge pipe and the second branch pipe. It is being supplied.

Further, when only the second compressor is operated, the oil returned from the second branch pipe to the one of the first branch pipe and the refrigerant suction mother pipe is sucked into the second compressor. Therefore, the oil returned to the refrigerant suction mother pipe from the oil return pipe is supplied to the second compressor from the oil return pipe. As a result, in the compression mechanism of this refrigeration system, it is possible to operate one unit by either one of the first and second compressors, while improving the reliability of oil supply to the first and second compressors.

According to a second aspect of the compression mechanism of the refrigeration system, in the first aspect, the oil return pipe is connected to the first branch pipe. The first branch pipe is formed so as to have a downward slope from the connection portion with the oil return pipe to the connection portion with the refrigerant suction mother pipe. In the compression mechanism of this refrigeration apparatus, the oil returned from the oil return pipe returns to the refrigerant suction mother pipe by gravity in the first branch pipe. As a result, when operating only the second compressor, the oil returned from the oil return pipe is
Easy to be sucked into the compressor.

According to a third aspect of the present invention, in the compression mechanism of the refrigerating apparatus according to the first or second aspect, the second branch pipe has a downward slope from the connection portion with the oil discharge pipe to the connection portion with the refrigerant suction mother pipe. Is formed in. In the compression mechanism of this refrigeration system, the oil discharged from the oil discharge pipe is returned to the refrigerant suction mother pipe by gravity in the second branch pipe. This makes it easier for the oil returned from the oil discharge pipe to be sucked into the first compressor when operating only the first compressor.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (1) Configuration of Refrigerant Circuit and Compression Mechanism of Air Conditioner FIG. 1 is a schematic diagram of a refrigerant circuit of an air conditioner 1 according to an embodiment of the present invention. The air conditioning apparatus 1 includes one outdoor unit 2 and a plurality of indoor units 3 connected in parallel to the outdoor unit 2, and is used for air conditioning of a building, for example. The outdoor unit 2 mainly has a compression mechanism 11, a four-way switching valve 12, and an outdoor heat exchanger 13. The indoor unit 3 mainly has an expansion valve 14 and an indoor heat exchanger 15. These devices 11, 12, 13, 14, and 15 are sequentially connected by a refrigerant pipe to form a refrigerant circuit of the air conditioner 1.

The compression mechanism 11 is a mechanism for compressing the refrigerant gas that has been heat-exchanged in the indoor heat exchanger 15 of the indoor unit 2 and returned to the outdoor unit 2. As shown in FIG. -Type first compressor 21 and low-pressure dome-type second compressor 2
2, a refrigerant suction mother pipe 23, a first branch pipe 24, a second
A branch pipe 25, an oil discharge pipe 26, an oil separator 27,
And an oil return pipe 28. The refrigerant suction mother pipe 23 is
It is connected to the outlet of the four-way switching valve 12. Oil separator 27
The refrigerant pipe at the outlet of is connected to the inlet of the four-way switching valve 12.

The first compressor 21 has an oil sump portion 21a provided on the refrigerant gas discharge side. Second compressor 2
2 is an oil sump 22a provided on the suction side of the refrigerant gas
And is connected in parallel with the first compressor 21. The first branch pipe 24 branches from the refrigerant suction mother pipe 23 and is connected to the suction side of the first compressor 21. The second branch pipe 25 branches from the refrigerant suction mother pipe 23 and is connected to the suction side of the second compressor 22.

The oil discharge pipe 26 is connected to the first compressor 21 and the second compressor 21.
It is connected to the branch pipe 25. That is, the first compressor 21
The oil can be discharged from the oil sump portion 21a toward the second branch pipe 25. The oil discharge pipe 26 can discharge oil to the second branch pipe 25 while keeping the amount of oil in the oil sump 21a at the specified value V. Oil separator 2
7 is connected to the discharge sides of the first compressor 21 and the second compressor 22, and separates oil from the refrigerant compressed by the first compressor 21 and the second compressor 22.

The oil return pipe 28 connects the oil separator 27 to one of the first branch pipe 24 and the refrigerant suction mother pipe 23.
In the present embodiment, the oil return pipe 28 is connected to the first branch pipe 24. Further, the first branch pipe 24 is formed so as to have a downward slope from the connection portion with the oil return pipe 28 toward the connection portion with the refrigerant suction mother pipe 23 (see wedge symbol A in FIG. 2). .

The second branch pipe 25 extends from the oil return pipe 28 to the first branch pipe 24 when only the second compressor 22 is operated.
The oil returned to one of the refrigerant suction mother pipe 23 is connected to the second compressor 22 so as to be sucked into the second compressor 22. In the present embodiment, the second branch pipe 25 is formed so as to have a downward slope from the connection portion with the oil discharge pipe 26 toward the connection portion with the refrigerant suction mother pipe 23 (wedge symbol in FIG. 2). (See B).

(2) Operation of the compression mechanism Next, the operation of the compression mechanism 11 of this embodiment will be described. When operating the two-unit operating air conditioner 1 at full load, the compression mechanism 1
1 is the simultaneous operation of the first and second compressors 21 and 22. Then, the refrigerant is compressed by the compression mechanism 11, the four-way switching valve 12,
It circulates in the refrigerant circuit constituted by the outdoor heat exchanger 13, the expansion valve 14, and the indoor heat exchanger 15, and returns to the compression mechanism 11. At this time, oil is supplied to the first compressor 21 from the oil separator 27 via the oil return pipe 28 and the first branch pipe 24, and the second compressor 22 is discharged with oil from the first compressor 21. Oil is supplied through the pipe 26 and the second branch pipe 25. Here, the oil discharge pipe 26 supplies oil to the second branch pipe while keeping the oil amount in the oil sump portion 21 a of the first compressor 21 at the specified value V, so that the first compressor 2
The oil amount of 1 is always kept at a necessary amount. As a result, oil is supplied to the compressors 21 and 22.

Operation of the first compressor only When the air conditioner 1 is operated in a low load state such as a half load, the compression mechanism 11 operates only the first compressor 21. Then, together with the oil supplied from the oil return pipe 28 to the first compressor 21 via the first branch pipe 24, the oil discharge pipe 26 and the second branch pipe 25 from the first compressor 21.
The oil to be returned to the refrigerant suction mother pipe 23 via the is supplied. Here, the oil returns from the second branch pipe 25 to the refrigerant suction mother pipe 23 because the second branch pipe 25 descends from the connection portion with the oil discharge pipe 26 toward the connection portion with the refrigerant suction mother pipe 23. This is because the oil is returned by gravity.

As described above, when the air conditioner 1 is operated under a low load, the high pressure dome type first compressor 21 is operated because the high pressure dome type compressor is a low pressure dome type compressor. This is because the pressure loss on the suction side is smaller than that of the compressor, and the heat generated by the motor is less likely to be added to the suction refrigerant gas, which is efficient. Operation of only the second compressor When the air conditioner 1 is started, particularly when restarted after a long-term stop, the compression mechanism 11 operates only the second compressor 22. Then, the oil returned from the oil return pipe 28 to the refrigerant suction mother pipe 23 via the first branch pipe 24 is supplied to the second compressor 22. Here, the oil returns from the first branch pipe 24 to the refrigerant suction mother pipe 23 because the first branch pipe 24 is connected to the oil return pipe 28 from the connection portion of the refrigerant suction mother pipe 2.
This is because the oil is returned by gravity because it is formed so as to have a downward slope toward the connection portion with 3.

As described above, the reason why the low pressure dome type second compressor 22 is started after the long-term stop is that the low pressure dome type compressor has a larger volume on the suction side than the high pressure dome type compressor. This is because the compressor is less likely to be damaged even when a liquid-blended refrigerant is sucked by the liquid bag. Therefore, when restarting at the time of short-term stop, since there is little risk of liquid backing, the first compressor 21 of the high-pressure dome type may be started.

(3) Features of the compression mechanism The compression mechanism 11 of this embodiment has the following features. Configuration of Oil Pipe that Enables Single Unit Operation In the compression mechanism 11 of the present embodiment, the oil return pipe 28 is connected to the first branch pipe 24 so that it can be returned to the suction side of the high-pressure dome type first compressor 21. When connected, the oil pressure of the oil sump 21a of the first compressor 21 is the low pressure dome type second.
Utilizing that the pressure is higher than that on the suction side of the compressor 22,
An oil discharge pipe 26 that supplies oil from the first compressor 21 to the second branch pipe 25 is provided. In addition, the oil discharge pipe 26
Supplies oil to the second branch pipe while maintaining the oil amount in the oil sump 21a of the first compressor 21 at the specified value V, the oil amount in the first compressor 21 is always set to the required amount. It is designed to be kept. With such a configuration of the compression mechanism 11, while improving the reliability of the oil supply to the first and second compressors 21 and 22, the two-unit operation and the first and second compressors as described above are performed.
Only one of the compressors 21 and 22 can be operated.

Further, in the compression mechanism 11 of this embodiment, the first branch pipe 24 is formed so as to have a downward slope from the connection portion with the oil return pipe 28 toward the connection portion with the refrigerant suction mother pipe 23. Therefore, when operating only the second compressor 22, the oil returned from the oil return pipe 28 is easily sucked into the second compressor 22. Further, in the compression mechanism 11 of the present embodiment, the second branch pipe 25 is formed so as to have a downward slope from the connection portion with the oil discharge pipe 26 toward the connection portion with the refrigerant suction mother pipe 23. When only the first compressor 21 is operated, the oil returned from the oil discharge pipe 26 is easily sucked into the first compressor 21.

Increasing the efficiency of the compression mechanism during operation of one unit In the compression mechanism 11 of this embodiment, one of the compressors 21 and 22 can be operated as described above, so the air conditioner 1 is half-loaded. When operating in a low load state such as, the high-pressure dome type first compressor 21 alone enables efficient operation. Countermeasure against liquid back at startup after long-term stop Since the compression mechanism 11 of the present embodiment can operate one of the compressors 21 and 22 as described above, the air conditioner 1 is restarted after long-term stop. At this time, it is possible to start only with the low-pressure dome-type second compressor 22 that is strong against liquid back.

(4) Other Embodiments The embodiments of the present invention have been described above with reference to the drawings. However, the specific configuration is not limited to these embodiments, and does not depart from the gist of the invention. It can be changed with. For example, except for the compression mechanism, the configuration of the refrigerant circuit that configures the air conditioner, and the types and radix of the indoor unit and the outdoor unit are not limited to those in the above embodiment.

Further, in the above-described embodiment, the common oil separator for the first compressor and the second compressor is provided, but it may be provided for each compressor.

[0030]

As described above, according to the present invention, the following effects can be obtained. In the invention according to claim 1, an oil discharge pipe for supplying oil from the first compressor to the second branch pipe and an oil return pipe for returning oil from the oil separator to the first compressor are provided. By this, oil can be supplied when each one of the first and second compressors is in operation, so that the reliability of the oil supply to the first and second compressors is improved and the first and second compressions are performed. One unit can be operated by either one of the machines.

In the invention according to claim 2, since the oil returned from the oil return pipe returns to the refrigerant suction mother pipe by gravity in the first branch pipe, only the second compressor is operated. The oil returned from the oil return pipe is easily sucked into the second compressor. In the invention according to claim 3, since the oil discharged from the oil discharge pipe returns to the refrigerant suction mother pipe by gravity in the second branch pipe, the oil discharge occurs when only the first compressor is operated. The oil returned from the pipe is easily sucked into the first compressor.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a refrigerant circuit of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG. 1, showing a compression mechanism.

FIG. 3 is a schematic diagram of a refrigerant circuit of a conventional air conditioner.

FIG. 4 is a partially enlarged view of FIG. 3 showing a conventional compression mechanism.

[Explanation of symbols]

11 compression mechanism 21 first compressor 22 Second compressor 23 Refrigerant suction mother tube 24 First Branch Pipe 25 Second branch pipe 26 Oil discharge pipe 27 oil separator 28 Oil return piping

Claims (3)

[Claims] 1. A compression mechanism (11) used in a refrigeration apparatus of a refrigerant compression type, comprising a high-pressure dome type first compressor (21) and a first compressor (21) connected in parallel. A low pressure dome type second compressor (22), a refrigerant suction mother pipe (23), and a branch from the refrigerant suction mother pipe (23) and connected to the suction side of the first compressor (21). First branch pipe (24)
And a second branch pipe (25) branched from the refrigerant suction mother pipe (23) and connected to the suction side of the second compressor (22).
An oil discharge pipe (26) for connecting the first compressor (21) and the second branch pipe (25), the first compressor (21) and the second compressor (22) An oil separator (27) connected to the discharge side of the oil separator for separating oil from the refrigerant compressed by the first compressor (21) and the second compressor (22), and the oil separator (27). ) And an oil return pipe (28) for connecting one of the first branch pipe (24) and the refrigerant suction mother pipe (23), and the second branch pipe (25) is the second pipe. Compressor (22)
When operating only the oil, the oil returned from the oil return pipe (28) to one of the first branch pipe (24) and the refrigerant suction mother pipe (23) is sucked into the second compressor (22). The oil discharge pipe (26) is connected from the first compressor (21) to the second branch pipe (25) when only the first compressor (21) is operated. The compression mechanism (11) of the refrigeration system, which is connected so that the oil released to the refrigerant is returned to the refrigerant suction mother pipe (23). 2. The oil return pipe (28) is connected to the first branch pipe (24), and the first branch pipe (24) is the oil return pipe (28).
The compression mechanism (11) of the refrigeration system according to claim 1, wherein the compression mechanism (11) is formed so as to have a downward slope from a connection part with the refrigerant suction mother pipe (23). 3. The second branch pipe (25) is connected to the oil discharge pipe (26) from the refrigerant suction mother pipe (23).
The compression mechanism (1) of the refrigeration system according to claim 1 or 2, wherein the compression mechanism (1) is formed so as to have a downward slope toward a connection portion with
1).