U.S. patent application number 12/105458 was filed with the patent office on 2008-09-04 for system and method for controlling air conditioner.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Sung Oh Choi, Il Nahm Hwang, Sung Chun Kim, Yoon Been Lee, Jong Han Park, Young Min Park, Dong Jun Yang, Seok Ho Yoon.
Application Number | 20080209928 12/105458 |
Document ID | / |
Family ID | 34386782 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080209928 |
Kind Code |
A1 |
Hwang; Il Nahm ; et
al. |
September 4, 2008 |
SYSTEM AND METHOD FOR CONTROLLING AIR CONDITIONER
Abstract
A system for controlling an air conditioner includes a plurality
of outdoor units each having at least one compressor and an outdoor
heat exchanger, an indoor unit connected to the outdoor units by a
refrigerant tube, the indoor unit having an indoor heat exchanger,
and a pressure regulating tube for equalizing pressure according to
an operation mode. The pressure regulating tube is connected
between the outdoor units.
Inventors: |
Hwang; Il Nahm; (Ansan-si,
KR) ; Park; Young Min; (Incheon-si, KR) ; Lee;
Yoon Been; (Seoul, KR) ; Yang; Dong Jun;
(Seoul, KR) ; Yoon; Seok Ho; (Seoul, KR) ;
Park; Jong Han; (Gwangmyeong-si, KR) ; Choi; Sung
Oh; (Gwangmyeong-si, KR) ; Kim; Sung Chun;
(Seoul, KR) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
LG Electronics Inc.
Seoul
KR
|
Family ID: |
34386782 |
Appl. No.: |
12/105458 |
Filed: |
April 18, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10929456 |
Aug 31, 2004 |
|
|
|
12105458 |
|
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|
Current U.S.
Class: |
62/175 |
Current CPC
Class: |
F25B 49/022 20130101;
F25B 49/025 20130101; F25B 2400/06 20130101; Y02B 30/70 20130101;
F25B 2700/2106 20130101; F25B 2600/021 20130101; Y02B 30/741
20130101; F25B 2700/21152 20130101; F25B 13/00 20130101; F25B
2400/075 20130101; F25B 2313/0253 20130101; F25B 2313/0233
20130101 |
Class at
Publication: |
62/175 |
International
Class: |
F25B 7/00 20060101
F25B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2003 |
KR |
10-2003-0072992 |
Claims
1. A system for controlling an air conditioner, comprising: a
plurality of outdoor units each having at least one compressor and
an outdoor heat exchanger; at least one indoor unit connected to at
least one of the outdoor units by a refrigerant tube, the indoor
unit having an indoor heat exchanger; and a pressure regulating
tube for equalizing pressure according to an operation mode, the
pressure regulating tube being connected to the outdoor units.
2. The system according to claim 1, wherein the pressure regulating
tube is varied in a connection location to the outdoor heat
exchangers according to the operation mode.
3. The system according to claim 1, wherein the pressure regulating
tube is connected between refrigerant tubes extending from rear
ends of the heat exchangers where low pressure is formed in a
heating mode.
4. The system according to claim 1, wherein the pressure regulating
tube is connected between refrigerant tubes extending from front
ends of the outdoor heat exchangers where high pressure is formed
in a cooling mode.
5. The system according to claim 1, wherein the pressure regulating
tube has a diameter less that of the refrigerant tube.
6. The system according to claim 1, wherein the outdoor units
comprise first and second outdoor units, the first outdoor unit
comprising an inverter compressor and a constant compressor, the
second outdoor unit comprising a compressor, the number of
compressors of the second outdoor unit being less than that of the
first outdoor unit to generate a pressure difference between the
heat exchanger of the first outdoor unit and the heat exchanger of
the second outdoor unit, the pressure difference being compensated
by the pressure regulating tube.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of pending U.S. patent
application Ser. No. 10/929,456, filed Aug. 31, 2004, the
disclosure of which is expressly incorporated herein by reference
in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a system and method for
controlling an air conditioner, and more particularly, to a system
and method for controlling an air conditioner, which can uniformly
maintain high and low pressures for respective cooling and heating
modes by disposing a pressure regulating tube between main and sub
outdoor heat exchangers.
[0004] The present invention further relates to a system and method
for controlling an air conditioner that can prevent a liquid
refrigerant from one-sidedly flowing to one of main and sub
compressors by controlling the air conditioner based on an exhaust
temperature of the compressors and an exhaust temperature according
to an environmental condition.
[0005] 2. Description of the Related Art
[0006] Generally, an air conditioner can be classified according to
its function into a cooling-only type, a heating-only type, and a
cooling-heating type. The air conditioner can be further classified
according to its unit constitution into an integral type where a
cooking unit and a heat discharge unit are integrated and a
separation type where a cooling unit is disposed at an indoor and
heat discharge and compressing units are disposed at an
outdoor.
[0007] The separation type includes a multi-type where more than
two indoor units are connected to a singe outdoor unit to control
air in a plurality of indoor spaces.
[0008] FIG. 1 shows a prior multi-type air conditioner.
[0009] As shown in the drawing, a prior multi-type air conditioner
comprises a plurality of indoor units 20a, 20b and 20c disposed in
the respective indoors and an outdoor unit. The air conditioner can
be selectively operated in cooling and heating modes.
[0010] The outdoor unit is divided into a main outdoor unit 10 and
a sub outdoor unit 10a. The main outdoor unit 10 comprises an
inverter compressor 11 for varying a driving RPM by varying an
operating frequency, a constant compressor 11a driven constantly,
an accumulator 14 for separating liquid, a four-way valve 13, a
condenser 15 for heat-exchanging, and an outdoor fan 16. The sub
outdoor unit 10a has an identical structure to the main outdoor
unit 10.
[0011] Each of the indoor units 20a, 20b and 20c comprises a
dispenser 21, an expansion valve 22a, (22b and 22c), an indoor heat
exchangers 23a (23b and 23c), and an indoor fan 24a (24b and
24c).
[0012] The heating and cooling modes of the above-described air
conditioner will be described hereinafter.
[0013] In the cooling mode, as shown in FIG. 1, gaseous refrigerant
introduced from the indoor heating exchangers 23a, 23b and 23c into
the compressors 11, 11a, 12 and 12a of the main and sub outdoor
units 10 and 10a is compressed into a
high-temperature/high-pressure state by the compressors 11, 11a, 12
and 12a and is discharged to outdoor heat exchangers 15 and 15a
through the four-way valves 13 and 13a that are converted for
realizing a cooling cycle.
[0014] The refrigerant discharged into the main and sub outdoor
heat exchangers 15 and 15a is phase-changed into a
high-temperature/high-pressure liquid state by being heat-exchanged
with outdoor air introduced into the outdoor units 10 and 10a by
the outdoor fans 16 and 16a.
[0015] The phase-changed refrigerant is directed to the expansion
valves 22a, 22b and 22c of the indoor units 20a, 20b and 20c
through the dispenser 21.
[0016] The refrigerant directed to the expansion valves 22a, 22b
and 22c is changed into a low-temperature/low-pressure liquid state
and is then directed to the indoor heat exchangers 23a, 23b and
23c.
[0017] The refrigerant directed to the indoor heat exchangers 23a,
23b and 23c is heat-exchanged with air around the heat exchangers
to be phase-changed into a low-temperature/low-pressure gaseous
state and is then introduced into the compressors 11, 11a, 12 and
12a through the four way valves 13 and 13a.
[0018] The refrigerant pressure-reduced through the expansion
valves 22a, 22b and 22c is heat-exchanged in the respectively heat
exchangers 23a, 23b and 23c, in the course of which the ambient air
is changed into cool air and is then discharged into the indoors by
the indoor fans 24a, 24b and 24c, completing a cycle of cooling
process.
[0019] The heating mode is operated in an opposite cycle to that of
the cooling mode. That is, as shown in FIG. 2,
low-temperature/low-pressure gaseous refrigerant introduced from
the outdoor heating exchangers (condensers) 15 and 15a into the
compressors 11, 11a, 12 and 12a of the main and sub outdoor units
10 and 10a is compressed into a high-temperature/high-pressure
gaseous state by the compressors 11, 11a, 12 and 12a and is
discharged to the indoor heat exchangers 23a, 23b and 23c through
the four-way valves 13 and 13a that are converted for realizing a
heating cycle. The refrigerant discharged into the indoor heat
exchangers 23a, 23b and 23c is phase-changed into a
high-temperature/high-pressure liquid state by being heat-exchanged
with indoor air. The phase-changed refrigerant is directed to the
expansion valves 22a, 22b and 22c, in the course of which, the
ambient air is changed into warm air by being heat-exchanged with
the high-temperature/high-pressure refrigerant and is then
discharged into the indoors to increase the temperature of the
indoor air.
[0020] The refrigerant directed to the expansion valves 22a, 22b
and 22c is changed into a low-temperature/low-pressure liquid state
and is then directed to the outdoor heat exchangers 15 and 15a. The
refrigerant directed to the outdoor heat exchangers 15 and 15a is
heat-exchanged with air introduced into the main and sub outdoor
units 10 and 10a to be phase-changed into a
low-temperature/low-pressure gaseous state and is then introduced
into the compressors 11, 11a, 12 and 12a through the four way
valves 13 and 13a.
[0021] However, in the above-described heating mode, as shown in
FIG. 2, since there is a difference in a flow rate of the
refrigerated between the inverter compressor 11 of the main outdoor
unit 10 and the constant compressor 12 of the outdoor unit 10a, a
pressure difference between the main outdoor heat exchanger 15 and
the sub outdoor heat exchanger 15a is incurred, whereby frost may
be formed on the main outdoor heat exchanger 15 that is relatively
low in the pressure, thereby deteriorating the heat-exchange
efficiency.
[0022] The deterioration of the heat-exchange efficiency
deteriorates the heating capability of the indoor units 20a, 20b
and 20c, thereby deteriorating the reliability of the air
conditioner.
[0023] Furthermore, since the refrigerant of the heat exchanger is
accumulated in the accumulator, the liquid refrigerant is inclined
into one of the main and sub compressors. This may cause the
compressors to be damaged.
SUMMARY OF THE INVENTION
[0024] Accordingly, the present invention is directed to a system
and method for controlling an air conditioner, which substantially
obviate one or more problems due to limitations and disadvantages
of the related art.
[0025] It is a first object of the present invention to provide a
system and method for controlling an air conditioner, which can
improve the reliability of the air conditioner by preventing frost
from being formed on the outdoor heat exchanger.
[0026] It is a second object of the present invention to provide a
system and method for controlling an air conditioner, which can
prevent liquid refrigerant from being one-sidedly flowing to one of
main and sub compressors, thereby preventing the compressor from
being damaged.
[0027] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0028] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, there is provided a system for
controlling an air conditioner, comprising: a plurality of outdoor
units each having at least one compressor and an outdoor heat
exchanger; an indoor unit connected to the outdoor units by a
refrigerant tube, the indoor unit having an indoor heat exchanger;
and a pressure regulating tube for equalizing pressure according to
an operation mode, the pressure regulating tube being connected
between the outdoor units.
[0029] In another aspect of the present invention, there is
provided a method for controlling an air conditioner, comprising
the steps of: determining if a compressor is driven for more than a
predetermined time; measuring a discharge temperature of the
compressor when the compressor is driven for more than the
predetermined time; comparing the measured temperature with a
predetermined temperature; and controlling an opening of an
electronic expansion valve is controlled such that the discharge
temperature can be increased to be higher than a current super
heating when the measured temperature is lower than the
predetermined temperature.
[0030] In another aspect of the present invention, there is
provided a method for controlling an air conditioner, comprising
the steps of: determining if a compressor is driven for more than a
predetermined time; measuring a discharge temperature of the
compressor when the compressor is driven for more than the
predetermined time; comparing the measured temperature with a
temperature predetermined according to an outdoor temperature; and
controlling an opening of an electronic expansion valve is
controlled such that the discharge temperature can be increased to
be higher than a current super heating when the measured
temperature is lower than the predetermined temperature.
[0031] In still another aspect of the present invention, there is
provided a method for controlling an air conditioner, comprising
the steps of: determining if a compressor is driven for more than a
predetermined time; measuring a discharge temperature of the
compressor when the compressor is driven for more than the
predetermined time; comparing the measured temperature with a
temperature predetermined according to a vaporizing temperature;
and controlling an opening of an electronic expansion valve is
controlled such that the discharge temperature can be increased to
be higher than a current super heating when the measured
temperature is lower than the predetermined temperature.
[0032] In still yet another aspect of the present invention, there
is provided a method for controlling an air conditioner, comprising
the steps of: driving a first compressor; determining if the first
compressor is driven for more than a predetermined time; measuring
a discharge temperature of the first compressor when the first
compressor is driven for more than the predetermined time;
comparing the measured temperature with a predetermined
temperature; replacing the first compressor with a second
compressor when the measured temperature is lower than the
predetermined temperature; and vaporizing liquid refrigerant in the
first compressor by pre-heating liquid refrigerant in the first
compressor.
[0033] According to the present invention, as the pressure
regulating tube is disposed between the main outdoor heat exchanger
and the sub outdoor heat exchanger, the formation of the frost on
the main outdoor heat exchanger can prevented, thereby improving
the reliability of the air conditioner.
[0034] That is, the pressure regulating tube equalizes the
refrigerant pressures directed to the main and sub outdoor heat
exchangers, the frost is not formed on the main outdoor heat
exchanger, improving the heat exchange efficiency and the
reliability of the air conditioner.
[0035] In addition, after the main and sub outdoor compressors are
driven for a predetermined time, the one-sided flow of the
refrigerant to one of the main and sub compressors can be prevented
by control factors such as the discharge temperature of the
compressors, the outdoor temperature, and/or the vaporizing
temperature, thereby preventing the compressors from being
damaged.
[0036] Furthermore, since the equal refrigerant pressure is applied
to both the main and sub sides, an effect where a capacity of the
sub side is increased can be obtained.
[0037] In addition, since amounts of the liquid refrigerant
accumulated in the accumulator can be equalized to each other by
the pressure regulating tube, the reliability of the air
conditioner can be further improved.
[0038] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] The accompanying drawings, which are included to provide a
further understanding of the invention, are incorporated in and
constitute a part of this application, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0040] FIG. 1 is a schematic view illustrating a cooling cycle of a
multi air conditioner according to the prior art;
[0041] FIG. 2 is a schematic view illustrating a heating cycle of a
multi air conditioner according to the prior art;
[0042] FIGS. 3 and 4 are schematic views of a multi air conditioner
according to an embodiment of the present invention;
[0043] FIGS. 5a and 5b are schematic views illustrating a pressure
regulating process between main and sub outdoor heat exchangers
through a pressure regulating tube in a cooling mode according to
an embodiment of the present invention;
[0044] FIGS. 6a and 6b are schematic views illustrating a pressure
regulating process between main and sub outdoor heat exchangers
through a pressure regulating tube in a heating mode according to
an embodiment of the present invention;
[0045] FIG. 7 is a flowchart illustrating a method for preventing
liquid refrigerant from one-sidedly flow to one of main and sub
compressors in a heating mode by comparing a discharge temperature
of a compressor driven for above a predetermined time with a
predetermined discharge temperature according to a first embodiment
of the present invention;
[0046] FIG. 8 is a graph illustrating a discharge temperature
considering an outdoor temperature;
[0047] FIG. 9 is a flowchart illustrating a method for preventing
liquid refrigerant from one-sidedly flow to one of main and sub
compressors in a heating mode by comparing a discharge temperature
of a compressor driven for above a predetermined time with a
discharge temperature predetermined according to an outdoor
temperature according to a second embodiment of the present
invention;
[0048] FIG. 10 is a graph illustrating a discharge temperature
considering a vaporizing temperature;
[0049] FIG. 11 is a flowchart illustrating a method for preventing
liquid refrigerant from one-sidedly flow to one of main and sub
compressors in a heating mode by comparing a discharge temperature
of a compressor driven for above a predetermined time with a
discharge temperature predetermined according to a vaporizing
temperature according to a third embodiment of the present
invention; and
[0050] FIG. 12 is a flowchart illustrating a method for preventing
liquid refrigerant from one-sidedly flow to one of main and sub
compressors in a heating mode by comparing a discharge temperature
of a compressor driven for above a predetermined time with a
discharge predetermined discharge temperature according to a fourth
embodiment of the present invention;
DETAILED DESCRIPTION OF THE INVENTION
[0051] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0052] FIGS. 3 and 4 shows schematic views of a multi air
conditioner according to an embodiment of the present
invention;
[0053] As shown in the drawings, the inventive multi air
conditioner comprises main and sub outdoor units 10 and 10a having
compressors 11 and 11a, 12 and 12a, respectively and main and sub
outdoor heat exchangers 15 and 15a; a plurality of outdoor units
20a, 20b, and 20c; and a pressure regulating tube 30 connected
between the main outdoor heat exchanger 15 and the sub outdoor heat
exchanger 15a to uniformly maintain the pressure in cooling and
heating modes.
[0054] In the heating mode, there is a difference in a refrigerant
amount between the inverter compressor 11 of the main outdoor unit
10 and the constant compressor 12 of the sub outdoor unit 10a.
Therefore, a pressure level of the main outdoor heat exchanger 15
becomes lower than that of the sub outdoor heat exchanger 15a.
[0055] Accordingly, frost may be formed on the main outdoor heat
exchanger 15, thereby deteriorating the exchange efficiency and the
reliability of the air conditioner. In order to prevent this, the
pressure regulating tube 30 is disposed between the main outdoor
heat exchanger 15 and the sub outdoor heat exchanger 15a to
constantly maintain the pressure in the cooling and heating
modes.
[0056] The pressure regulating tube is connected between
refrigerant tubes extending from rear ends of the heat exchangers
15 and 15a when low pressure is formed in the heating mode.
[0057] In addition, the pressure regulating tube is connected
between refrigerant tubes extending from front ends of the heat
exchangers 15 and 15a where high pressure is formed in the cooling
mode.
[0058] A diameter of the pressure regulating tube 30 is designed to
be less than those of the refrigerant tubes, being greater than 3/4
inch.
[0059] The pressure regulating process using the pressure
regulating tube disposed between the main and sub outdoor heat
exchangers 15 and 15a will be described hereinafter.
[0060] FIGS. 5a and 5b shows a pressure regulating process between
main and sub outdoor heat exchangers through a pressure regulating
tube in a cooling mode according to an embodiment of the present
invention;
[0061] FIGS. 6a and 6b shows a pressure regulating process between
main and sub outdoor heat exchangers through a pressure regulating
tube in a heating mode according to an embodiment of the present
invention;
[0062] In the cooling mode, a high-temperature/high-pressure
gaseous refrigerant discharged from the inverter and constant
compressors 11 and 11a of the main outdoor unit 10 and a
high-temperature/high-pressure gaseous refrigerant discharged from
the constant compressor 12 of the sub outdoor unit 10a are directed
to the main and sub outdoor heat exchangers 15 and 15a through
four-way valves 13 and 13a.
[0063] At this point, since the main outdoor unit is designed
having a large capacity as both the inverter and constant
compressors 11 and 11a are driven while the sub outdoor unit is
designed having a relatively small capacity as only the constant
compressor 12 is driven, there is a difference in a refrigerant
amount between the main compressors 11 and 11a of the main outdoor
unit 10 and the constant compressor 12 of the sub outdoor unit 10a.
Therefore, a pressure level of the main outdoor heat exchanger 15
becomes different from that of the sub outdoor heat exchanger
15a.
[0064] At this point, as shown in FIGS. 5a and 5b, the refrigerant
flows from a high pressure main side to a low pressure sub side to
realize pressure equality. Then, the refrigerant flows to the main
and sub outdoor heat exchangers 15 and 15a. As a result, the heat
exchangers 15 and 15a are operated under an identical refrigerant
pressure level.
[0065] In the heating mode, a high-temperature/high-pressure
gaseous refrigerant discharged from the inverter and constant
compressors 11 and 11a of the main outdoor unit 10 and a
high-temperature/high-pressure gaseous refrigerant discharged from
the constant compressor 12 of the sub outdoor unit 10a are directed
to the indoor heat exchangers 23a, 23b and 23c and condensed
therein. The condensed refrigerant is then directed to main and sub
outdoor heat exchangers 15 and 15a via the expansion valves 22a,
22b and 22c. At this point, likewise the cooling mode, there is a
difference in a refrigerant amount between the main compressors 11
and 11a of the main outdoor unit 10 and the constant compressor 12
of the sub outdoor unit 10a. Therefore, a pressure level of the
main outdoor heat exchanger 15 becomes different from that of the
sub outdoor heat exchanger 15a.
[0066] At this point, as shown in FIGS. 6a and 6b, by the pressure
regulating tube 30, the pressure level of the main outdoor heat
exchanger 15 is equalized to that of the sub outdoor heat exchanger
15a. Therefore, the formation of the frost on the main outdoor heat
exchanger 15 can be reduced or prevented. Particularly, since the
amount of the refrigerant directed to the compressors 11 and 11a
and 12 are equalized to each other, the accumulation amounts of the
liquid refrigerant in accumulators 14 and 14a are equalized to each
other, thereby improving the reliability of the air
conditioner.
[0067] The pressure regulating tube 30 of the present invention can
be applied to an automatic converting type multi air conditioner as
well as a manual converting type multi air conditioner. When the
pressure regulating tube 30 is applied to the automatic converting
type multi air conditioner, the air conditioner may more enjoy the
pressure regulating effect.
[0068] A method for controlling the air conditioner with the
pressure regulating tube 30 to prevent the liquid refrigerant from
one-sidedly flowing to one of the main compressor 11 (11a) and the
sub compressor 12 (12a) in the heating mode will be described
hereinafter.
[0069] The control of the air conditioner is realized based on 1) a
discharge temperature of the compressors 11, 11a, 12 and 12a driven
for above a predetermined time, 2) a discharge temperature
predetermined according to an outdoor temperature, 3) a discharge
temperature predetermined according to a vaporizing
temperature.
[0070] For the descriptive convenience, the compressors 11 and 11a
of the main outdoor unit will be represented as the inverter
compressor 11 and the compressors 12 and 12a of the sub outdoor
unit will be represented as the constant compressor 12.
[0071] FIG. 7 is a flowchart illustrating a method for preventing
liquid refrigerant from one-sidedly flow to one of the inverter and
constant compressors 11 and 12 in the heating mode by comparing the
discharge temperature of a compressor driven for above a
predetermined time with the discharge predetermined discharge
temperature according to a first embodiment of the present
invention.
[0072] As shown in FIG. 7, the compressors 11 and 12 are first
driven and it is determined if the compressors 11 and 12 are driven
for above a predetermined time, for example, for above 10 minutes
(S701).
[0073] When the compressors 11 and 12 are driven for less than 10
minutes, the refrigerant introduced from the heat exchanger (the
indoor heat exchanger in the cooling mode or the outdoor heat
exchanger in the heating mode) into the compressors is in a liquid
state.
[0074] Accordingly, in order to determine if an operating state
reaches the normal state where the refrigerant introduced into the
compressors is not in the liquid state, the driving time is set at
above 10 minutes. The driving time may be varied.
[0075] When the compressors 11 and 12 are driven for more than 10
minutes, a discharge temperature of the compressors 11 and 12 is
measured (S703).
[0076] Then, it is determined if the measured temperature is less
than a predetermined temperature 75.degree. C. (S 705).
[0077] When the measure temperature of at least one of the
compressors 11 and 12 is less than 75.degree. C. and the
refrigerant in the compressor is in a liquid state, the opening of
the electronic expansion valve is controlled such that the
discharge temperature can greater than a current super heating by
10.degree. C. (S707). In the flowchart of FIG. 7, SH indicates the
super heating, Shnew indicates a new super heating, and Shold
indicates a current super heating.
[0078] By controlling the opening of the electronic expansion
valve, the increase of the oil delivering amount due to the
introduction of the liquid refrigerant and the damage of the
compressor due to the abrasion of the compression part can be
prevented.
[0079] Next, it is determined if the discharge temperature of the
compressor is increased to be higher than the predetermined
discharge temperature by 5.degree. C., i.e., increased above
80.degree. C. (S709).
[0080] When the discharge temperature of the compressor is
increased above 80.degree. C., it is returned to a former super
heating state for the normal operation (S711 and S713).
[0081] When the discharge temperature of the compressor is not
increased above 80.degree. C., the opening of the electronic
expansion valve is repeatedly controlled until the discharge
temperature of the compressor is increased to be higher than the
predetermined discharge temperature by 5.degree. C.
[0082] The predetermined temperature is not limited to 75.degree.
C., but may be varied.
[0083] FIG. 8 shows a graph illustrating a discharge temperature
considering the outdoor temperature. That is, the graph shows that
the reference discharge temperature may be varied according to the
outdoor temperature.
[0084] FIG. 9 shows a flowchart illustrating a method for
preventing liquid refrigerant from one-sidedly flow to one of the
inverter and constant compressors 11 and 12 in the heating mode by
comparing a discharge temperature of the compressor driven for
above a predetermined time with a discharge temperature
predetermined according to an outdoor temperature according to a
second embodiment of the present invention.
[0085] As shown in FIG. 9, the compressors 11 and 12 are first
driven and it is determined if the compressors 11 and 12 are driven
for above a predetermined time, for example, for more than 10
minutes (S901).
[0086] When the compressors 11 and 12 are driven for less than 10
minutes, the refrigerant introduced from the heat exchanger (the
indoor heat exchanger in the cooling mode or the outdoor heat
exchanger in the heating mode) into the compressors is in a liquid
state.
[0087] Accordingly, in order to determine if an operating state
reaches the normal state where the refrigerant introduced into the
compressors is not in the liquid state, the driving time is set at
above 10 minutes. The driving time may be varied.
[0088] When the compressors 11 and 12 are driven for more than 10
minutes, a discharge temperature of the compressors 11 and 12 and
the outdoor temperature are measured (S903).
[0089] Then, it is determined if the measured temperature is less
than a predetermined temperature 75.degree. C. that is
predetermined according to the outdoor temperature (S 905).
[0090] When the measure temperature of at least one of the
compressors 11 and 12 is less than 75.degree. C. and the
refrigerant in the compressor is in a liquid state, the opening of
the electronic expansion valve is controlled such that the
discharge temperature can be greater than a current super heating
by 10.degree. C. (S907).
[0091] By controlling the opening of the electronic expansion
valve, the increase of the oil delivering amount due to the
introduction of the liquid refrigerant and the damage of the
compressor due to the abrasion of the compression part can be
prevented.
[0092] Next, it is determined if the discharge temperature of the
compressor is increased to be higher than the discharge temperature
predetermined according to the outdoor temperature by 5.degree. C.,
i.e., increased above 80.degree. C. (S909).
[0093] When the discharge temperature of the compressor is
increased above 80.degree. C., it is returned to a former super
heating state for the normal operation (S911 and S913).
[0094] When the discharge temperature of the compressor is not
increased above 80.degree. C., the opening of the electronic
expansion valve is repeatedly controlled until the discharge
temperature of the compressor is increased to be higher than the
predetermined discharge temperature by 5.degree. C.
[0095] FIG. 10 shows a graph illustrating a discharge temperature
considering the vaporizing temperature. That is, the graph shows
that the reference discharge temperature may be varied according to
the vaporizing temperature.
[0096] FIG. 11 shows a flowchart illustrating a method for
preventing liquid refrigerant from one-sidedly flow to one of the
inverter and constant compressors 11 and 12 in the heating mode by
comparing a discharge temperature of the compressor driven for
above a predetermined time with a discharge temperature
predetermined according to a vaporizing temperature according to a
third embodiment of the present invention.
[0097] As shown in FIG. 11, the compressors 11 and 12 are first
driven and it is determined if the compressors 11 and 12 are driven
for above a predetermined time, for example, for more than 10
minutes (S1101).
[0098] When the compressors 11 and 12 are driven for less than 10
minutes, the refrigerant introduced from the heat exchanger (the
indoor heat exchanger in the cooling mode or the outdoor heat
exchanger in the heating mode) into the compressors is in a liquid
state.
[0099] Accordingly, in order to determine if an operating state
reaches the normal state where the refrigerant introduced into the
compressors is not in the liquid state, the driving time is set at
above 10 minutes. The driving time may be varied.
[0100] When the compressors 11 and 12 are driven for more than 10
minutes, a discharge temperature of the compressors 11 and 12 and
the vaporizing temperature are measured (S1103).
[0101] Then, it is determined if the measured temperature is less
than a predetermined temperature 75.degree. C. that is
predetermined according to the vaporizing temperature (S1105).
[0102] When the measure temperature of at least one of the
compressors 11 and 12 is less than 75.degree. C. and the
refrigerant in the compressor is in a liquid state, the opening of
the electronic expansion valve is controlled such that the
discharge temperature can be greater than a current super heating
by 10.degree. C. (S1107).
[0103] By controlling the opening of the electronic expansion
valve, the increase of the oil delivering amount due to the
introduction of the liquid refrigerant and the damage of the
compressor due to the abrasion of the compression part can be
prevented.
[0104] Next, it is determined if the discharge temperature of the
compressor is increased to be higher than the discharge temperature
predetermined according to the vaporizing temperature by 5.degree.
C., i.e., increased above 80.degree. C. (S1109).
[0105] When the discharge temperature of the compressor is
increased above 80.degree. C., it is returned to a former super
heating state for the normal operation (S1111 and S1113).
[0106] When the discharge temperature of the compressor is not
increased above 80.degree. C., the opening of the electronic
expansion valve is repeatedly controlled until the discharge
temperature of the compressor is increased to be higher than the
predetermined discharge temperature by 5.degree. C.
[0107] FIG. 12 shows a flowchart illustrating a method for
preventing liquid refrigerant from one-sidedly flow to one of the
main and sub compressors 11 and 12 in a heating mode by comparing a
discharge temperature of a compressor driven for above a
predetermined time with a discharge predetermined discharge
temperature according to a fourth embodiment of the present
invention.
[0108] As shown in FIG. 12, the compressor 11 is first driven and
it is determined if the compressor 11 and 12 is driven for above a
predetermined time, for example, for more than 20 minutes
(S1201).
[0109] When the compressor 11 is driven for less than 20 minutes,
the refrigerant introduced from the heat exchanger (the indoor heat
exchanger in the cooling mode or the outdoor heat exchanger in the
heating mode) into the compressor is in a liquid state.
[0110] Accordingly, in order to determine if an operating state
reaches the normal state where the refrigerant introduced into the
compressor is not in the liquid state, the driving time is set at
above 20 minutes. The driving time may be varied.
[0111] When the compressor 11 is driven for more than 20 minutes, a
discharge temperature of the compressor 11 is measured (S1203).
[0112] Then, it is determined if the measured temperature is less
than a predetermined temperature 60.degree. C. (S1205).
[0113] When the measured temperature is greater than 60.degree. C.,
the current operating state is maintained (S 1215).
[0114] However, when the measure temperature of the compressor 11
is less than 60.degree. C. and the operating compressor is replaced
from the compressor 11 to another compressor 12, after which the
compressor 11 is pre-heated by a heat disposed on a bottom of the
compressor 11 to vaporize the liquid refrigerant (S1207).
[0115] That is, when the discharge temperature of the compressor 11
is less than 60.degree. C. regardless of the outdoor temperature,
since the refrigerant is discharged in the liquid state even the
compressing operation of the compressor 11, the compressor 11 is
replaced with the compressor 12 in operation and is pre-heated by
the heater to vaporize the liquid refrigerant.
[0116] Next, it is determined if the compressor 11 is pre-heated
for more than 1 hour (S1209).
[0117] When the compressor 11 is pre-heated for more than 1 hour,
the compressor 11 is operated again (S1211).
[0118] However, even when the compressor 11 is operated again, if
the refrigerant in the compressor is discharged in the liquid
state, a malfunction of the compressor is noted through, for
example, an LED so that the user can repair the compressor 11
(S1213).
[0119] As described above, as the pressure regulating tube is
disposed between the main outdoor heat exchanger and the sub
outdoor heat exchanger, the formation of the frost on the main
outdoor heat exchanger can prevented, thereby improving the
reliability of the air conditioner.
[0120] That is, the pressure regulating tube equalizes the
refrigerant pressures directed to the main and sub outdoor heat
exchangers, the frost is not formed on the main outdoor heat
exchanger, improving the heat exchange efficiency and the
reliability of the air conditioner.
[0121] In addition, after the main and sub outdoor compressors are
driven for a predetermined time, the one-sided flow of the
refrigerant to one of the main and sub compressors can be prevented
by control factors such as the discharge temperature of the
compressors, the outdoor temperature, and/or the vaporizing
temperature, thereby preventing the compressors from being
damaged.
[0122] Furthermore, since the equal refrigerant pressure is applied
to both the main and sub sides, an effect where a capacity of the
sub side is increased can be obtained.
[0123] In addition, since amounts of the liquid refrigerant
accumulated in the accumulator can be equalized to each other by
the pressure regulating tube, the reliability of the air
conditioner can be further improved.
[0124] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention.
Thus, it is intended that the present invention covers the
modifications and variations of this invention provided they come
within the scope of the appended claims and their equivalents.
* * * * *