EP1655555A2

EP1655555A2 - Air conditioner

Info

Publication number: EP1655555A2
Application number: EP05256788A
Authority: EP
Inventors: Bong-Soo Gwanak Dreamtown 115-1804 Park; Sai-Kee Hyangchon Lotte Apt. 308-706 Oh; Chi-Woo Song; Ju-Won Kim; Baik-Young Chojeongmaeul Chung; Se-Dong Jugong Apt. 516-702 Chang
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2004-11-03
Filing date: 2005-11-02
Publication date: 2006-05-10
Also published as: US20060090487A1; KR20060039739A; EP1655555A3; CN1769804A; KR100619756B1

Abstract

An air conditioner includes: at least one indoor unit (10); an outdoor unit (20) communicating with the indoor unit and having at least one compressor (23) and one outdoor heat exchanger (41,41'); a fluid path opening/closing valve (55) for opening or closing a fluid path through which a refrigerant can flow to the outdoor heat exchanger; and a control unit (51) for controlling the compressor and the fluid path opening/closing valve to perform appropriate compression and condensation of the refrigerant according to the load amount of the indoor unit. Accordingly, as the air conditioner comprises the fluid path opening/closing valve and the branch fluid path opening/closing valve which are capable of opening or closing fluid paths and a control unit for controlling the valves, a high pressure of a cycle is appropriately maintained even during small-load operation and therefore reliability in operation can be increased.

Description

The present invention relates to an air conditioner. It more particularly relates to an air conditioner capable of appropriately maintaining a high pressure of a cycle during small-load operation.
Air conditioners adjust temperature, humidity, air current and cleanliness of air in order to create a pleasant indoor environment. According to their unitary construction, air conditioners can be classified as integral type air conditioners in which an indoor unit and an outdoor unit are received inside one single case, and separated type air conditioners in which a compressor and a condenser as an indoor unit are separated from an evaporator as an outdoor unit.
An air conditioner for both heating and cooling, which is part of the air conditioner, is provided with a fluid path switch valve and switches a fluid path of a refrigerant to thereby selectively perform its cooling or heating function. Recently, the use of the so-called multi-type air conditioner having a plurality of indoor units capable of cooling or heating according to indoor spaces has been increasing.
In a multi-type air conditioner, a plurality of outdoor units having a plurality of compressors and a plurality of outdoor heat exchangers are connected to each other in parallel.
Figure 1 is a schematic view of a conventional multi-type air conditioner. With reference to Figure 1, a conventional multi-type air conditioner includes: a plurality of indoor units 10 having indoor heat exchangers 11 and indoor expansion devices 13, and a plurality of outdoor units 20 having outdoor heat exchangers 41 and compressors 23. With the construction of Figure 1, the outdoor units 20 supply the compressed refrigerant to each of the indoor units 10 via a pipe 30, and cool spaces where the indoor units 10 are installed.
Meanwhile, the multi-air conditioner performs condensation by using the outdoor heat exchangers 41 of all the outdoor units 20, even when some indoor units 10 perform cooling operations. As a result, a condenser which is large in comparison to the area and air flow of the heat exchangers corresponding to the indoor unit 10 load is used. Accordingly, a phenomenon that the system high pressure decreases occurs.
When the phenomenon that the system high pressure decreases occurs, a difference between a high pressure and a low pressure is reduced and therefore the refrigerant cannot be smoothly supplied to the indoor units 10 when the pipe 30 for connecting the indoor units 10 and the outdoor units 20 to each other is long or when a difference in altitude between the indoor units 10 and the outdoor units 20 is great. In addition, since the lower pressure decreases simultaneously when the high pressure of the system decreases, the pipe of the indoor units 10 can become frozen. In particular, such a phenomenon frequently occurs at low outdoor temperatures.
Accordingly, the refrigerant cannot be smoothly supplied to the indoor units 10 and the pipe of the indoor units 10 can become frozen. Thus, cooling or heating becomes impossible.
The present invention seeks to provide an improved air conditioner.
The invention provides an air conditioner comprising: at least one indoor unit; an outdoor unit communicating with the indoor unit and having at least one compressor and one outdoor heat exchanger; a fluid path opening/closing valve for opening or closing a fluid path through which a refrigerant can flow to the outdoor heat exchanger; and a control unit for controlling the compressor and the fluid path opening/closing valve to perform appropriate compression and condensation of the refrigerant according to the load amount of the indoor unit.
Embodiments of the invention will now be described by way of non-limiting example only, with reference to the drawings, in which:

Figure 1 is a schematic view of a conventional multi-type air conditioner;
Figure 2 is a construction view of an air conditioner in accordance with a first embodiment of the present invention;
Figure 3 is a control block diagram of Figure 2;
Figure 4 is a construction view of an air conditioner in accordance with a second embodiment of the present invention;
Figure 5 is a construction view showing an important part of an air conditioner in accordance with a third embodiment of the present invention;
Figure 6 is a control block diagram of Figures 4 and 5;
Figure 7 is a construction view of an air conditioner in accordance with a fourth embodiment of the present invention; and
Figure 8 is a control block diagram of Figure 7.

For reference, a construction showing the same operation and effect as the aforementioned and illustrated construction will be given the same reference numerals, and a description therefor will be omitted.
With reference to Figures 2 and 3, an air conditioner in accordance with the first embodiment includes an indoor unit 10, an outdoor unit 20, a fluid path opening/closing valve 55 and a control unit 51.
Each of the indoor units 10 is disposed indoors, and includes an indoor heat exchanger 11, a cooling fan (not illustrated) disposed to promote heat exchange of the indoor heat exchanger 11 and an indoor expansion device 13 disposed at one side of the indoor heat exchanger 11 so as to expand a refrigerant.
The outdoor unit 20 includes compressors 23 for compressing a refrigerant and a pair of outdoor heat exchangers 41 and 41' connected with the compressors 23.
The compressors 23 are connected to each other via a flow pipe 25 through which oil can flow, and each of the compressors 23 has an oil separator 27 and a check valve 29 at its discharge side.
The downstream side of the check valves 29 along the direction of the refrigerant flow join together at a confluence junction. A four-way valve 31 is installed on the downstream side of the confluence junction so as to switch a fluid path of the refrigerant.
Each port of the four-way valve 31 communicates with each one end of connection pipes 33 connected with the indoor heat exchangers 41 and 41', an accumulator 35 and the indoor unit 10, respectively.
Check valves 43 and outdoor expansion devices 45 are provided on the downstream side of the outdoor heat exchangers 41 and 41', respectively, along the direction of the refrigerant flow.
The fluid path opening/closing valve 55 is disposed on the upstream side of the outdoor heat exchanger 41' along the direction of the refrigerant flow. The fluid path opening/closing valve 55 blocks the fluid path of the refrigerant during small-load operation, and comprises an electric valve such as solenoid in order to allow the control by an electric signal.
The control unit 51 is implemented in the form of MICOM having a control program therein and is electrically connected with the compressors 23 and the fluid path opening/closing valve 55. The control unit 51 calculates the load during small-load operation by which some indoor units 10 are operated, and appropriately controls compression and condensation on the basis of the calculated load.
Hereinafter, the operation of an air conditioner illustrated in Figures 2 and 3 will be described.
When some indoor units 10 are operated, the control unit 51 calculates the cooling or heating load. Of course, the control unit 51 can calculate the cooling or heating load when all the indoor units 10 are operated.
According to the calculated cooling or heating load, the control unit 51 control the compressors 23 such that some compressors 23 are operated or the compressors 23 are operated at low frequencies.
In addition, the control unit 51 controls the fluid path opening/closing valve 55 such that the compressed refrigerant flows or does not flow to the outdoor heat exchanger 41'. The compressors 23 and the fluid path opening/closing 55 can be simultaneously or sequentially controlled as occasion demands.
Accordingly, the air conditioner having the construction of Figures 2 and 3 can perform condensation corresponding only to the amount of the indoor unit 10 load when some indoor units 10 perform cooling or heating operation, so that a decrease of the system high pressure does not occur.
With reference to Figure 4, an air conditioner in accordance with a second embodiment includes an indoor unit 10, an outdoor unit 20, a fluid path opening/closing valve 55, a branch fluid path opening/closing valve 49 and a control unit 51.
Since the indoor unit 10 has the same construction and operation as the indoor unit 10 described in the first embodiment, a description therefor will be omitted.
The outdoor unit 20 includes compressors 23 for compressing a refrigerant and outdoor heat exchangers 41 and 41' connected with the compressors 23.
Since the compressor 23 has the same construction and operation as the compressor 23 described in the first embodiment, a description therefor will be omitted.
In order that the optimum amount of refrigerant can flow, the outdoor heat exchangers 41 and 41' include a plurality of heat exchange units 42 separated from each other; headers 47 having branch fluid paths through which the refrigerant branches off and is supplied to each of the heat exchange units 42; and distributors 57, respectively.
The branch fluid path includes a plurality of upstream branch fluid paths 48 for connecting the header 47 with the heat exchange unit 42, and a plurality of downstream branch fluid paths 58 for connecting the heat exchange unit 42 with the distributor 57.
The fluid path opening/closing valve 55 is installed on the upstream side of the header 47 of the outdoor heat exchanger 41', and opens or closes the corresponding fluid path.
The branch fluid path opening/closing valve 49 is installed on the upstream branch path 48 of the outer heat exchanger 41, and opens or closes the upstream branch fluid path 48 along the direction of the refrigerant flow.
Figure 5 illustrates an air conditioner according to a third embodiment in which a location where the branch fluid path opening/closing valve 49 is installed is changed from the upstream branch fluid path 48 of Figure 4 to the downstream branch fluid path 58. With reference to Figure 5, the branch fluid path opening/closing valve 49 opens or closes the downstream branch fluid path 58. Of course, the branch fluid path opening/closing valves 49 can be installed at both the upstream branch fluid path 48 and the downstream branch fluid paths 58.
With reference to Figure 6, the control 51 is implemented as MICOM having a control program therein, and is electrically connected with the compressors 23, the fluid path opening/closing valve 55 and the branch fluid path opening/closing valve 59. The control unit 51 calculates the load during small-load operation by which some indoor units 10 are operated. On the basis of the calculated load, the control unit 51 appropriately controls compression and condensation of the refrigerant.
Hereinafter, the operation of the air conditioner illustrated in Figures 4 to 6 will be described.
When some indoor units 10 perform cooling operations, the control unit 51 calculates the cooing or heating load. Of course, if all the indoor units 10 perform cooling operations, the control unit 51 can calculate the cooling or heating load.
According to the calculated cooling or heating load, the control unit 51 controls the compressors 23 such that some compressors 23 are operated or the compressors 23 are operated at low rates.
In addition, the control unit 51 controls the fluid path opening/closing valve 55 such that the compressed refrigerant flows or does not flow to the outdoor heat exchanger 41'.
In addition, the control unit 51 controls the branch fluid path opening/closing valve 49 such that the compressed refrigerant flows or does not flow to the outdoor heat exchanger 41.
The compressors 23, the fluid path opening/closing valve 55 and the branch fluid path opening/closing valve 49 can be simultaneously or sequentially controlled as occasion demands.
Accordingly, the air conditioner having the construction of Figures 4 to 6 can perform condensation corresponding to the amount of the indoor unit 10 load when some indoor units 10 perform cooling or heating operation, so that the decrease of the system high pressure does not occur.
With reference to Figures 7 and 8, the air conditioner in accordance with the fourth embodiment includes an indoor unit 10, an outdoor unit 20, a fluid path opening/closing valve 55, a branch fluid path opening/closing valve 59 and a control unit 51.
Since the indoor unit 10 has the same construction and operation as the indoor unit described in the first embodiment, a description therefor will be omitted.
The outdoor unit 20 includes a main outdoor unit 21 a and a sub-outdoor unit 21 b connected and installed in parallel.
The main outdoor unit 21 a and the sub-outdoor unit 21 b include a plurality of compressors 23, a plurality of outdoor heat exchangers 41 and 41' and accumulators 35 and four-way valves 31, respectively.
Oil separators 27 and check valves 29 are installed at discharge sides of the compressors 23 of the main outdoor unit 21 a and the sub-outdoor unit 21 b, respectively.
A pressure equalizing pipe 15 is provided between the main outdoor unit 21 a and the sub-outdoor unit 21 b so as to allow the upstream side of the outdoor heat exchangers 41 and 41' of the main outdoor unit 21 a and the upstream side of the outdoor heat exchangers 41 and 41' of the sub-outdoor unit 21 b to communicate with each other along the direction of the refrigerant flow.
The fluid path opening/closing valves 55 are installed on the upstream side of the outdoor heat exchanger 41 and 41' of the main outdoor unit 21 a and on the upstream of the outdoor heat exchangers 41 and 41' of the sub-outdoor unit 21 b, respectively, so as to open or close the corresponding fluid path along the direction of the refrigerant flow.
The branch fluid path opening/closing valve 59 is installed at the downstream branch fluid path 58 of the outdoor heat exchanger 41 of the main outdoor unit 21 a so as to open or close the corresponding branch fluid path 58.
With reference to Figure 8, the control unit 51 is implemented in the form of MICOM having a control program therein, and is electrically connected with the compressors 23, the fluid path opening/closing valve 55 and the branch fluid path opening/closing valve 59.
The control unit 51 calculates the load during small-load operation by which some indoor units 10 are operated and appropriately controls compression and condensation on the basis of the calculated load.
Hereinafter, the operation of the air conditioner illustrated in Figures 7 and 8 will be described.
When some indoor units 10 perform cooling operations, the control unit 51 calculates the cooling or heating load. Of course, when all the indoor units 10 perform cooling operations, the control unit 51 can calculate the cooling or heating load.
According to the calculated cooling or heating load, the control unit 51 controls the compressors 23 such that some compressors 23 are operated or the compressors 23 are operated at low rates.
In addition, the control unit 51 controls the fluid path opening/closing valve 55 such that the compressed refrigerant can flow or cannot flow to the outdoor heat exchanger 41 and 41' of the main outdoor unit 21 a and to the outdoor heat exchangers 41 and 41' of the sub-outdoor unit 21 b.
In addition, the control unit 51 controls the branch fluid path opening/closing path 49 such that the compressed refrigerant can flow or cannot flow to the outdoor heat exchanger 41 of the main outdoor unit 21 a.
The compressor 23, the fluid path opening/closing valve 55 and the branch fluid path opening/closing valve 59 can be simultaneously or sequentially controlled as occasion demands.
Accordingly, the air conditioner having the construction of Figure 4 to 6 can perform condensation corresponding to the amount of the indoor unit 10 load when some indoor units 10 perform cooling or heating operation, so that the decrease of the system high pressure does not occur.
The air conditioner in accordance with one embodiment of the present invention of which description has been made so far includes the fluid path opening/closing valve and the branch fluid path opening/closing valve which are capable of opening or closing fluid paths and a control unit for controlling the valves. Accordingly, even during the small-load operation, a high pressure of a cycle is appropriately maintained to thusly increase reliability in operation.
As the present invention may be embodied in several forms without departing from the essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the bounds of the claims, or equivalents thereof are therefore intended to be embraced by the claims.

Claims

An air conditioner comprising:
at least one indoor unit;

an outdoor unit communicating with the indoor unit and having at least one compressor and one outdoor heat exchanger;

a fluid path opening/closing valve for opening or closing a fluid path through which a refrigerant can flow to the outdoor heat exchanger; and

a control unit for controlling the compressor and the fluid path opening/closing valve to perform appropriate compression and condensation of the refrigerant according to the load amount of the indoor unit.
The air conditioner of claim 1, wherein the control unit comprises means to control the compressors according to the load amount obtained by calculating the load when some indoor units are operated such that some compressors are operated or the compressors are operated at low rates, and opens or closes the fluid path opening/closing valve.
The air conditioner of claim 1, wherein the outdoor heat exchanger comprises:
a plurality of heat exchange units in which the refrigerant branches off and flows, and performing heat exchange;

a header having branch fluid paths through which the refrigerant can branch off and be supplied to the heat exchange units; and

a distributor connected with the heat exchange units.
The air conditioner of claim 3, further comprising:
a branch fluid path opening/closing valve for opening or closing the branch fluid path.
The air conditioner of claim 4, wherein the branch fluid path comprises:
an upstream branch fluid path for connecting the header with the heat exchange units; and

a downstream fluid path for connecting the heat exchange units and the distributor,

wherein the branch fluid path opening/closing valve is installed at either the upstream branch fluid path or the downstream branch fluid path.
The air conditioner of claim 4, wherein the branch fluid path comprises:
an upstream branch fluid path through which the header is connected with the heat exchange units; and

a downstream fluid path through which the heat exchange units are connected with the distributor,

wherein the branch fluid path opening/closing valves are installed at both the upstream branch fluid path and the downstream branch fluid path.
The air conditioner of claim 4, wherein the control unit comprises means to control the compressors according to the load amount obtained by calculating the load when some indoor units are operated, such that some compressors are operated or the compressors are operated at low rates, and opens or closes the fluid path opening/closing valve and the branch fluid path opening/closing valve.
The air conditioner of claim 4, wherein the outdoor unit comprises a main outdoor unit and a sub-outdoor unit connected and installed in parallel.
The air conditioner of claim 8, further comprising:
a pressure equalizing pipe for allowing the upstream side of the outdoor heat exchanger of the main outdoor unit and the upstream side of the outdoor heat exchanger of the sub-outdoor unit to communicate with each other.
The air conditioner of claim 8, wherein the fluid path opening/closing valves are installed on the upstream side of the outdoor heat exchanger of the main outdoor unit and on the upstream side of the outdoor heat exchanger of the sub-outdoor unit.
The air conditioner of claim 8, wherein the branch fluid path opening/closing valve is installed at the downstream branch fluid path of the outdoor heat exchanger of the main outdoor unit.
The air conditioner of claim 8, wherein the control unit comprises means to control the compressors according to the load amount obtained by calculating the load when some indoor units are operated, such that some compressors of the main outdoor unit and the sub-outdoor unit are operated or the compressors are operated at low rates, and opens or closes the fluid path opening/closing valve and the branch fluid path opening/closing valve.