EP1696189B1

EP1696189B1 - Air-conditioner having multiple compressors

Info

Publication number: EP1696189B1
Application number: EP05004194.6A
Authority: EP
Inventors: Cheol-Min Kim; Eun-Jun Hyundai Hometown Apt. 102-1304 Cho; Yoon-Jei Hwang; Yun-Ho Ryu; Chan-Ho Song; Won-Hee Lee; Chang-Min Choi
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2005-02-25
Filing date: 2005-02-25
Publication date: 2017-09-27
Anticipated expiration: 2025-02-25
Also published as: EP1696189A1

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air-conditioner and, more particularly, to an air-conditioner having four compressors according to the preamble of claim 1.

2. Description of the Background Art

In general, a heat-pump type air-conditioner can be operable both for air-cooling and air-heating. Namely, including an indoor heat exchanger and an outdoor heat exchanger, the heat-pump type air-conditioner can be used both as an air-cooling device and as an air-heating device by making a refrigerant of a refrigerating cycle to flow reversely.
Figure 1 shows the construction of a refrigerating cycle of the heat-pump type air-conditioner in accordance with a conventional art.
The conventional heat-pump type air-conditioner includes an indoor heat exchanger 102 installed indoors and performing air-cooling or air-heating, an outdoor heat exchanger 104 disposed outdoors and heat-exchanged with outdoor air; a four-way valve 106 for switching a flow of a refrigerant in a forward direction or a backward direction; an expansion valve 110 installed at a refrigerant pipe connecting the outdoor heat exchanger 104 and the indoor heat exchanger 102 and changing a refrigerant gas to have a low temperature and low pressure, compressors 112, 114, 116 and 118 for compressing a refrigerant to have a high temperature and high pressure, and an accumulator 130 connected to the compressors 112, 114, 116 and 118 by discharge pipes 120, 122, 124 and 126, separating the refrigerant into a gas and a liquid, and supplying the gaseous refrigerant to each compressor 112, 114, 116 and 118.
The compressors are the first compressor 112, the second compressor 114, the third compressor 116 and the fourth compressor 118, and check valves 140 are installed at discharge sides of each compressor 112, 114, 116 and 118 to prevent the refrigerant from flowing backward.
The accumulator 130 having a large capacity separates the refrigerant sucked through the refrigerant pipe 142 into a gas and a liquid and distributes the gaseous refrigerant to the first to fourth compressors 112, 114, 116 and 118.
As shown in Figure 2, the accumulator 130 includes a case 150 connected to the refrigerant pipe 142 through which the refrigerant is sucked thereinto and having a hermetic space, first to fourth discharge tubes 160, 162, 164 and 166 inserted for as long as a prescribed length into the case 150 from the lower side of the case 150 and supplying a gas refrigerant gasificated inside the case 150 to each compressor 112, 114, 116 and 118, a screen 152 installed at an upper portion inside the case 150, and a tube holder 154 for supporting the discharge tubes 160, 162, 164 and 166 inserted inside the case 150.
Oil contained in the refrigerant introduced through the refrigerant pipe 142 is stored at the side portion of the case 150, and oil retrieval holes 156 are formed respectively at one portion of the first to fourth discharge tubes 160, 162, 164. and 166. Accordingly, the oil stored at the lower portion of the case 150 is sucked into the oil retrieval holes 156 by virtue of a pressure of the refrigerant flowing in the first to fourth discharge tubes 160, 162, 164 and 166, and retrieved to each compressor 112,114,116 and 118, thereby performing a lubricating operation of the compressors.
However, the conventional heat-pump type air-conditioner has the following problems.
That is, since the first to fourth discharge tubes 160, 162, 164 and 166, which are respectively connected to the four compressors 112, 114, 116 and 118, are installed in one accumulator 130, the amount of oil sucked through each discharge tube 160, 162, 164 and 166 differs, and thus, some compressor(s) to which relatively less oil is retrieved can be damaged due to oil shortage.
In addition, since the four compressors are connected to one accumulator, a relatively large capacity accumulator is required. Then, it is not easy to secure an installation space for the large accumulator.
JP 08-159580 A discloses an air-conditioner with a configuration including two compressors and three accumulators. Moreover in JP 2006-023022 A an air-conditioner has a configuration in which a plurality of outdoor units are connected in parallel to increase freezing capability. The outdoor units are connected to two compressors and one accumulator is connected to the two compressors to provide a gaseous coolant, respectively.

SUMMARY OF THE INVENTION

Therefore, one object of the present invention is to provide an air-conditioner having multiple compressors, wherein oil is supplied uniformly to the compressors.
The above object is achieved by an air-conditioner having four compressors with the features of claim 1. Embodiments of the air-conditioner are defined in the dependent claims.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an air-conditioner having four compressors including: an indoor heat-exchanger disposed indoors and heat-exchanging indoor air; an outdoor heat-exchanger disposed outdoors and heat-exchanging a refrigerant with external air; an expansion valve installed at a refrigerant pipe connecting the indoor heat-exchanger and the outdoor heat-exchanger and changing the refrigerant to have a low temperature and low pressure; four compressors for compressing the refrigerant to change the refrigerant to have a high temperature and high pressure; and three accumulators disposed at a suction side of the four compressors and separating the refrigerant into a gas and a liquid to supply a gaseous refrigerant to the compressors.
The compressors are first, second, third and fourth compressors. Each compressor can have the same capacity or compressors with different capacities are applied at various rates.
The accumulators include a first accumulator for receiving the refrigerant and separating it into a gas and a liquid; a second accumulator connected to the first accumulator by a refrigerant pipe and connected to the first and second compressors; and a third accumulator connected to the first accumulator by a refrigerant pipe and connected to the third and fourth compressors.
The second accumulator is connected to the first compressor by a first pipe and to the second compressor by a second pipe, separates the refrigerant supplied to the first accumulator into a gas and a liquid, and supplies the gaseous refrigerant to the first and second compressors.
The third accumulator is connected to the third compressor by a third pipe and to the fourth compressor by a fourth pipe, separates the refrigerant supplied to the first accumulator into a gas and a liquid, and supplies the gaseous refrigerant to the third and fourth compressors.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:

Figure 1 shows the construction of a refrigerant cycle of a heat-pump type air-conditioner in accordance with a conventional art;
Figure 2 is a sectional view showing an accumulator in accordance with the conventional art;
Figure 3 shows the construction of a refrigerant cycle of a heat-pump type air-conditioner in accordance with the present invention; and
Figure 4 is a sectional view of an accumulator in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
There can be plural embodiments for the air-conditioner having four compressors in accordance with the present invention, of which the most preferred one will now be described.
Figure 3 shows the construction of a refrigerant cycle of a heat-pump type air-conditioner in accordance with the present invention.
The air-conditioner of the present invention includes an indoor heat-exchanger 2 disposed indoors and heat-exchanged with indoor air; outdoor heat- exchangers 4 and 6 disposed outdoors and heat-exchanged with external air; a four-way valve 8 for switching a flow of a refrigerant in a forward direction or a backward direction; compressors 20, 22, 24 and 26 for compressing the refrigerant to change it to have a high temperature and high pressure; and a plurality of accumulators 30, 32 and 35 for separating the refrigerant supplied to the compressors 20, 22, 24 and 26 into a gas and a liquid.
The outdoor heat- exchangers 4 and 6 are first outdoor heat exchanger 4 and second outdoor heat exchanger 6.
Expansion valves 10 are installed at refrigerant pipes 12 and 14 connecting the outdoor heat exchangers 4 and 6 and the indoor heat exchanger 2 in order to change the refrigerant to a low temperature and low pressure state.
The compressors refer to the first compressor 20, the second compressor 22, the third compressor 24 and the fourth compressor 26. The compressors 20, 22, 24 and 26 may have the same capacity. Or, compressors having different capacities at several rates can be adopted.
Check valves 16 are installed at each discharge side of the compressors 20, 22, 24 and 26 in order to prevent the refrigerant from flowing backward.
The accumulators 30, 32 and 34 include a first accumulator 30 connected to a four-way valve 8 by a refrigerant pipe 18 and separating the refrigerant introduced into the refrigerant pipe 18 into a gas and a liquid; a second accumulator 32 connected to the first accumulator 30 by the refrigerant pipe 40 and connected to the first and second compressors 20 and 22, and a third accumulator 34 connected to the first accumulator 30 by a refrigerant pipe 42 and connected to the third and fourth compressors 24 and 26.
The second accumulator 32 is connected to the first compressor 20 by a first pipe 50 and to the second compressor 22 by a second pipe 52, so that it can separate the refrigerant supplied to the first accumulator 30 into a gas and a liquid and supply the gaseous refrigerator to the first and second compressors 20 and 22.
The third accumulator 34 is connected to the third compressor 24 by a third pipe 54 and to the fourth compressor 26 by a fourth pipe 56, so that it can separate the refrigerant supplied to the first accumulator 30 into a gas and a liquid and supply the gaseous refrigerant to the third and fourth compressors 24 and 26.
The first, second and third accumulators have the same structure and may differ in their sizes depending on capacities of the compressors.
Of the accumulators 30, 32 and 34, the first accumulator 30 has the following structure.
As shown in Figure 4, the first accumulator 30 includes a case 60 connected to the four-way valve 8 by the refrigerant pipe 18 and having a hermetic space into which the refrigerant is sucked, first and second discharge tubes 62 and 64 inserted for as long as a prescribed length into the case 60 from the lower side of the case 60 and supplying a gaseous refrigerant gasificated inside the case 60 to the second and third accumulators 32 and 34, a screen 66 installed at an upper portion inside the case 60, and a tube holder 68 supporting the discharge tubes 62 and 64 installed inside the case 60.
Oil contained in the refrigerant sucked into the case 60 is stored at a lower portion inside the case 60, and oil retrieving holes 70 and 72 are formed at one portion of the first and second discharge tubes 62 and 64 sunk in the oil, so that oil stored at the lower portion of the case 60 is sucked through the oil retrieving holes 70 and 72 and retrieved to each compressor.
The oil stored in the case 60 has a suction force by virtue of a pressure of the refrigerant passing the first and second discharge tubes 62 and 64.
The air-conditioner constructed as described above in accordance with the present invention operates as follows.
When the compressors 20, 22, 24 and 26 are driven, a low temperature and low pressure refrigerant which has passed the indoor heat-exchanger 2 is introduced into the first accumulator 30 after passing through the four-way valve 8.
The refrigerant is gasificated and separated into a liquid and a gas in the first accumulator 30, and oil contained in the refrigerant is stored at a lower portion of the first accumulator 30.
The gaseous refrigerant which has been gasificated in the first accumulator is supplied to the second accumulator 32 through the first discharge tube 62 and the refrigerant pipe 40, and also to the third accumulator 34 through the second discharge tube 64 and the refrigerant pipe 42.
At this time, the oil stored at the lower portion of the first accumulator 30 is sucked through the oil retrieving holes 70 and 72 formed at the first and second discharge tubes 62 and 64 and supplied together with the gaseous refrigerant to the second and third accumulators 32 and 34.
The refrigerant which has been supplied in the second accumulator 32 is separated into a gas and a liquid, and the gaseous refrigerant after being gasificated in the second accumulator is supplied to the first compressor 20 through the first pipe 50 and to the second compressor 22 through the second pipe 52. At this time, the oil stored in the second accumulator 32 is retrieved together with the gaseous refrigerant into the first and second compressors 20 and 22 through the first and second pipes 50 and 52, to perform a lubricating operation of the compressors.
In this manner, the refrigerant and the oil are supplied only the two compressors 20 and 22 from the second accumulator 32, so that the amount of oil supplied to the first and second compressors 20 and 22 can be maintained constantly.
The refrigerant supplied to the third accumulator 34 is separated into a gas and a liquid, and the gaseous refrigerant after being gasified in the third accumulator 34 is supplied together with the oil stored in the third accumulator 34 to the third compressor 24 through the third pipe 54 and also to the fourth compressor 26 through the fourth pipe 56.
Herein, since the oil is supplied only to the two compressors 24 and 26 from the third accumulator 34, the amount of oil supplied to the third and fourth compressors 24 and 26 can be maintained constantly.
The process in which the refrigerant supplied to the first to fourth compressors 20, 22, 24 and 26 is compressed to be changed to have a high temperature and high pressure, supplied to the outdoor heat- exchangers 4 and 6 for heat-exchanging with external air, changed to have a low temperature and low pressure while passing the expansion valve 10, and then supplied to the indoor heat-exchanger 2, is repeatedly performed.
As so far described, the air-conditioner having four compressors in accordance with the present invention has the following advantages.
That is, for example, since the three accumulators and four compressors are provided and one accumulator is connected to two compressors, an interference generated in sucking oil or non-uniformity of the amount of oil supplied to each compressor due to a performance defection of compressors can be relatively reduced, and thus, reliability of the compressors can be enhanced.
In addition, since the three accumulators are small with a low capacity, their installation space can be easily secured.

Claims

An air-conditioner having four compressors (20,22,24,26) comprising:
an indoor heat-exchanger (2) disposed indoors for heat-exchanging indoor air;

an outdoor heat-exchanger (4,6) disposed outdoors for heat-exchanging a refrigerant with external air;

an expansion valve (10) installed at a refrigerant pipe connecting to between the indoor heat-exchanger and the outdoor heat-exchanger;

four compressors (20,22,24,26) for compressing the refrigerant to change the refrigerant to have a high temperature and high pressure, wherein the compressors are a first compressor (20), a second compressor (22), a third compressor (24) and a fourth compressor (26); wherein the air-conditioner comprises three accumulators (30,32,34) disposed at a suction passage of the four compressors (20,22,24,26) for separating the refrigerant into gas and liquid so as to supply a gaseous refrigerant to the compressors,

wherein the accumulators (30,32,34) comprise:
a first accumulator (30) for receiving the refrigerant from the indoor heat-exchanger (2) and separating refrigerant into a gas and a liquid;

a second accumulator (32) connected to the first accumulator (30) by a refrigerant pipe and connected to the first compressor (20) and the second compressor(22), the second accumulator (32) for receiving the refrigerant from the first accumulator (30) and separating refrigerant into a gas and a liquid; and

a third accumulator (34) connected to the first accumulator (30) by a refrigerant pipe (42) and connected to the third compressor (24) and the fourth compressor (26), the third accumulator (34) for receiving the refrigerant from the first accumulator (30) and separating refrigerant into a gas and a liquid, characterized in that the second accumulator (32) is connected to the first compressor (20) by a first pipe (50) and connected to the second compressor (22) by a second pipe (52) for separating the refrigerant supplied to the first accumulator(30) into gas and liquid so as to supply the gaseous refrigerant to the first compressor (20) and the second compressor (22), and

the third accumulator (34) is connected to the third compressor (24) by a third pipe (54) and to the fourth compressor (26) by a fourth pipe (26) for separating the refrigerant supplied to the first accumulator (30) into a gas and a liquid so as to supply the gaseous refrigerant to the third compressor (24) and the fourth compressor (26).
The air-conditioner of claim 1, wherein each compressor (20,22,24,26) can have the same capacity or compressors (20,22,24,26) with different capacities are adopted at various rates.
The air-conditioner of claim 2, wherein check valves (16) are installed at each discharge passage of the compressors for preventing a refrigerant from flowing backward.
The air-conditioner of claim 1, wherein the indoor heat-exchanger (2) performs air-cooling or air-heating, and wherein said air-conditioner further comprises; a four-way valve (8) for switching a flow of the refrigerant in a forward direction or backward direction.
The air-conditioner of claim 4, wherein each compressor (20,22,24,26) can have the same capacity or compressors with different capacities are adopted at various rates.
The air-conditioner of claim 5, wherein check valves (16) are installed at each discharge passage of the compressors (20,22,24,26) for preventing a refrigerant from flowing backward.
The air-conditioner of one of claims 1 to 6, wherein each accumulator (30,32,34) comprises:
a housing (60) connected to a refrigerant pipe (18,40,42) for sucking the refrigerant and storing oil contained in the refrigerant at a lower portion of the housing(60); and

two discharge tubes (62,64) inserted into the housing (60) from a lower portion of the housing (60) for discharging a gaseous refrigerant after being gasificated inside the housing (60),

wherein oil sucking holes (70,72) are formed at each lower portion of the two discharge tubes (62,64) inserted in the housing (60) in order to suck oil stored in the housing (60).