U.S. patent application number 11/249706 was filed with the patent office on 2006-04-20 for air conditioner.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Se Dong Chang, Song Choi, Baik Young Chung, Yoon Been Lee.
Application Number | 20060080990 11/249706 |
Document ID | / |
Family ID | 36179304 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060080990 |
Kind Code |
A1 |
Lee; Yoon Been ; et
al. |
April 20, 2006 |
Air conditioner
Abstract
Disclosed is an air conditioner. The air conditioner a main
compressor for compressing a refrigerant; a four-way valve disposed
at a discharge side of the main compressor and switching a fluid
path; an outdoor heat exchanger having one side connected with the
four-way valve; an indoor heat exchanger having one side connected
with the outdoor heat exchanger and the other side connected with
the four-way valve; an expansion valve disposed between the outdoor
heat exchanger and the indoor heat exchanger; and an auxiliary
compression unit for reducing the load on the main compressor.
Accordingly, since the load on the main compressor decreases,
efficiency and reliability of the main compressor are enhanced and
noises are reduced. In addition, an instrumental part such as a
bearing inside the main compressor is not subject to abrasion and
high heat damage to a motor unit is prevented.
Inventors: |
Lee; Yoon Been; (Seoul,
KR) ; Choi; Song; (Seoul, KR) ; Chung; Baik
Young; (Incheon, KR) ; Chang; Se Dong;
(Gyeonggi-Do, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG Electronics Inc.
|
Family ID: |
36179304 |
Appl. No.: |
11/249706 |
Filed: |
October 14, 2005 |
Current U.S.
Class: |
62/324.6 ;
62/324.1; 62/510 |
Current CPC
Class: |
F25B 1/10 20130101; F25B
2700/2106 20130101; F25B 31/004 20130101; F25B 13/00 20130101; F25B
2500/02 20130101; F25B 2700/1931 20130101; F25B 2700/1933
20130101 |
Class at
Publication: |
062/324.6 ;
062/324.1; 062/510 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F25B 1/10 20060101 F25B001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2004 |
KR |
83299/2004 |
Claims
1. An air conditioner comprising: a main compressor for compressing
a refrigerant; a four-way valve disposed at a discharge side of the
main compressor and switching a fluid path; an outdoor heat
exchanger having one side connected with the four-way valve; an
indoor heat exchanger having one side connected with the outdoor
heat exchanger and the other side connected with the four-way
valve; an expansion valve disposed between the outdoor heat
exchanger and the indoor heat exchanger; and an auxiliary
compression unit for reducing a load on the main compressor.
2. The air conditioner of claim 1, wherein the auxiliary
compression unit comprises: an auxiliary fluid path having one side
connected with the discharge side of the main compressor and the
other side connected to the upstream side of the four-way valve; a
sub-compressor disposed on the auxiliary fluid path and compressing
the refrigerant; an inlet-side opening/closing valve disposed at an
inlet side of the auxiliary fluid path and opening or closing the
auxiliary fluid path; and an outlet-side opening/closing valve
disposed at an outlet side of the auxiliary fluid path and opening
or closing the auxiliary fluid path.
3. The air conditioner of claim 2, wherein the auxiliary
compression unit further comprises: a pressure equalizing tank
disposed on the downstream side of the inlet-side opening/closing
valve for temporarily receiving the refrigerant compressed by the
main compressor.
4. The air conditioner of claim 3, wherein the auxiliary
compression unit further comprises: an oil return fluid path for
connecting the pressure equalizing tank with an intake side of the
main compressor such that oil of the pressure equalizing tank is
returned to the main compressor.
5. The air conditioner of claim 4, wherein the oil return fluid
path comprises: an oil return pipe having one side connected with
the pressure equalizing tank and the other side connected to the
intake side of the main compressor; and a return pipe
opening/closing valve for opening or closing the oil return
pipe.
6. The air conditioner of claim 4, wherein the oil return fluid
path includes a capillary tube.
7. The air conditioner of claim 2, further comprising: an
intake-side pressure sensor for detecting the pressure of the
intake side of the main compressor; a discharge-side pressure
sensor for detecting the pressure of the discharge side of the main
compressor; and a control unit for controlling the opening or
closing of the inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving signals of the intake-side
pressure sensor and the discharge-side pressure sensor.
8. The air conditioner of claim 7, wherein the control unit
includes a pressure difference calculating unit for calculating a
pressure difference between the intake side and the discharge side
of the main compressor.
9. The air conditioner of claim 2, further comprising: an ambient
air temperature sensor for detecting ambient air temperature; and
Is a control unit for controlling the opening or closing of the
inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving a signal of the ambient air
temperature sensor.
10. The air conditioner of claim 2, further comprising: an
intake-side pressure sensor for detecting the pressure of the
intake side of the main compressor; a discharge-side pressure
sensor for detecting the pressure of the discharge side of the main
compressor; an ambient air temperature sensor for detecting ambient
air temperature; and a control unit for controlling the opening or
closing of the inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving a signal of the ambient air
temperature sensor and controlling the opening or closing of the
inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving signals of the intake-side
pressure sensor and the discharge-side pressure sensor.
11. The air conditioner of claim 10, wherein the control unit
includes a pressure difference calculating unit for calculating a
pressure difference between the intake side and the discharge side
of the main compressor.
12. An air conditioner comprising: a main compressor for
compressing a refrigerant; a four-way valve disposed at a discharge
side of the main compressor and switching a fluid path; an outdoor
heat exchanger having one side connected with the four-way valve;
an indoor heat exchanger having one side connected with the outdoor
heat exchanger and the other side connected with the four-way
valve; an expansion valve disposed between the outdoor heat
exchanger and the indoor heat exchanger; an auxiliary fluid path
having one side connected with the discharge side of the main
compressor and the other side connected to the upstream side of the
four-way valve; a sub-compressor disposed on the auxiliary fluid
path and compressing the refrigerant; an inlet-side opening/closing
valve disposed at an inlet side of the auxiliary fluid path and
opening or closing the auxiliary fluid path; an outlet-side
opening/closing valve disposed at an outlet side of the auxiliary
fluid path and opening or closing the auxiliary fluid path; and a
pressure equalizing tank disposed on the downstream side of the
inlet-side opening/closing valve for temporarily receiving the
refrigerant compressed by the main compressor.
13. The air conditioner of claim 12, further comprising: an oil
return fluid path for connecting the pressure equalizing tank with
an intake side of the main compressor such that oil of the pressure
equalizing tank is returned to the main compressor.
14. The air conditioner of claim 13, wherein the oil return fluid
path comprises: an oil return pipe having one side connected with
the pressure equalizing tank and the other side connected to the
intake side of the main compressor; and a return pipe
opening/closing valve for opening or closing the oil return
pipe.
15. The air conditioner of claim 13, wherein the oil return fluid
path includes a capillary tube.
16. The air conditioner of claim 12, further comprising: an
intake-side pressure sensor for detecting the pressure of the
intake side of the main compressor; a discharge-side pressure
sensor for detecting the pressure of the discharge side of the main
compressor; and a control unit for controlling the opening or
closing of the inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving signals of the intake-side
pressure sensor and the discharge-side pressure sensor.
17. The air conditioner of claim 16, wherein the control unit
includes a pressure difference calculating unit for calculating a
pressure difference between the intake side and the discharge side
of the main compressor.
18. The air conditioner of claim 12, further comprising: an ambient
air temperature sensor for detecting ambient air temperature; Is
and a control unit for controlling the opening or closing of the
inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving a signal of the ambient air
temperature sensor.
19. The air conditioner of claim 12, further comprising: an
intake-side pressure sensor for detecting the pressure of the
intake side of the main compressor; a discharge-side pressure
sensor for detecting the pressure of the discharge side of the main
compressor; an ambient air temperature sensor for detecting ambient
air temperature; and a control unit for controlling the opening or
closing of the inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving a signal of the ambient air
temperature sensor and controlling the opening or closing of the
inlet-side opening/closing valve and the outlet-side
opening/closing valve by receiving signals of the intake-side
pressure sensor and the discharge-side pressure sensor.
20. The air conditioner of claim 19, wherein the control unit
includes a pressure difference calculating unit for calculating a
pressure difference between the intake side and the discharge side
of the main compressor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an air conditioner, and
particularly, to an air conditioner reducing a load on a compressor
when ambient air temperature is low during heating operation.
[0003] 2. Description of the Background Art
[0004] In general, an air conditioner is for adjusting temperature,
humidity, air current and cleanliness of air in order to create a
pleasant indoor environment.
[0005] According to the unit construction, there are an integral
type air conditioner in which an indoor unit and an outdoor unit
are received inside one single case and a separated type air
conditioner in which a compressor and a condenser as an indoor unit
are separated from an evaporator as an outdoor unit. Some air
conditioners can selectively perform their cooling or heating
functions by being provided with fluid path switch valves to switch
a fluid path of a refrigerant.
[0006] FIG. 1 is a schematic view illustrating a construction of a
conventional air conditioner for both cooling and heating, and FIG.
2 is a pressure-enthalpy diagram corresponding to ambient air
temperature of the air conditioner.
[0007] As illustrated in FIG. 1, a conventional air conditioner for
cooling and heating includes: a compressor 101 for compressing a
refrigerant; a four-way valve 103 disposed at a discharge side of
the compressor 101 so as to switch a fluid path of a refrigerant;
an outdoor heat exchanger 105 and an indoor heat exchanger 107
which are connected with the four-way valve 103 and in which the
refrigerant undergoes heat exchange; and an expansion valve 109
disposed between the outdoor heat exchanger 105 and the indoor heat
exchanger 107.
[0008] With the construction of FIG. 1, during cooling operation,
the four-way valve 103 switches the fluid path such that the
refrigerant compressed in the compressor 101 flows to the outdoor
heat exchanger 105. The refrigerant compressed in the compressor
101 undergoes heat exchange and then is condensed in the outdoor
heat exchanger 105. Then condensed refrigerant is decompressed and
expanded in the expansion valve 109. Thereafter, the refrigerant
performs cooling operation, undergoing heat exchange and absorbing
latent heat of evaporation in the indoor heat exchanger 107.
[0009] During heating operation, the four-way valve 103 switches
the fluid path such that the refrigerant compressed in the
compressor 101 flows to the indoor heat exchanger 107. The
refrigerant having undergone heat exchange in the indoor heat
exchanger 107 and performed heating operation is condensed, and
then is decompressed and expanded while passing the expansion valve
109. The decompressed and expanded refrigerant absorbs latent heat
and is evaporated in the outdoor heat exchanger 105. Here, as
illustrated in FIG. 2, the pressure-enthalpy diagram is formed in
an order of a loop 1->2->3->4 in which a difference
between a high-pressure side and a low-pressure side forms a first
value (.DELTA.P). Meanwhile, when ambient air temperature is very
low, the enthalpy diagram is formed in an order of a loop
1'->2'->3->4 in which the difference between the high
pressure and the low pressure forms a second value (.DELTA.P')
which is greater than the first value (.DELTA.P).
[0010] As the pressure difference increases from the first value
(.DELTA.P) to the second value (.DELTA.P'), the load on the
compressor 101 increases. Thus, efficiency and reliability of the
compressor 101 are deteriorated and noises are increased. In
addition, because of the increase in the compressor 101 load, an
instrumental part such as a bearing inside the compressor 101 is
subject to abrasion and a motor unit is subject to high heat
damage.
BRIEF DESCRIPTIOIN OF THE INVENTION
[0011] Therefore, an object of the present invention is to provide
an air conditioner reducing a load on a compressor when ambient air
temperature is low during heating operation.
[0012] 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 comprising:
a main compressor for compressing a refrigerant; a four-way valve
disposed at a discharge side of the main compressor and switching a
fluid path; an outdoor heat exchanger having one side connected
with the four-way valve; an indoor heat exchanger having one side
connected with the outdoor heat exchanger and the other side
connected with the four-way valve; an expansion valve disposed
between the outdoor heat exchanger and the indoor heat exchanger;
and an auxiliary compression unit for reducing the load on the main
compressor.
[0013] 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
[0014] 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.
[0015] In the drawings:
[0016] FIG. 1 is a schematic view illustrating a construction of a
conventional air conditioner for both cooling and heating;
[0017] FIG. 2 is a pressure-enthalpy diagram according to ambient
air temperature of the air conditioner of FIG. 1;
[0018] FIG. 3 is a schematic view of an air conditioner according
to a first embodiment of the present invention;
[0019] FIG. 4 is a view illustrating the operation of an auxiliary
compression unit of FIG. 3;
[0020] FIG. 5 is a control block diagram of the air conditioner of
FIG. 3;
[0021] FIG. 6 is a schematic view of an air conditioner in
accordance with a second embodiment of the present invention;
[0022] FIG. 7 is a view illustrating the operation of an auxiliary
compression unit of FIG. 6; and
[0023] FIG. 8 is a control block diagram of the air conditioner of
FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Hereinafter, an air conditioner in accordance with a first
embodiment of the present invention will be described in detail
with reference to the accompanying drawings. FIG. 3 is a schematic
view of an air conditioner in accordance with the first embodiment
of the present invention, FIG. 4 is a view showing the operation of
an auxiliary compression unit of FIG. 3, and FIG. 5 is a control
block diagram of the air conditioner of FIG. 3.
[0025] With reference to FIGS. 3 and 4, an air conditioner in
accordance with a first embodiment of the present invention
includes: a main compressor 11 to compress the refrigerant, a
four-way valve 13, an outdoor heat exchanger 15, an indoor heat
exchanger 17, an expansion valve 19 and an auxiliary compression
unit 20.
[0026] The four-way valve 13 is disposed at a discharge side of the
main compressor 11 and switches a fluid path of a refrigerant
according to its operating mode.
[0027] The outdoor heat exchanger 15 has one side connected with
the four-way valve 13 and the refrigerant undergoes heat
exchange.
[0028] The indoor heat exchanger 17 has one side connected with the
outdoor heat exchanger 15 and the other side connected with the
four-way valve 13 and the refrigerant undergoes heat exchange.
[0029] The expansion valve 19 is disposed between the outdoor heat
exchanger 15 and the indoor heat exchanger 17, and the refrigerant
is decompressed and expanded while passing through the expansion
valve 19.
[0030] The auxiliary compression unit 20 is installed between the
main compressor 11 and the four-way valve 13, and decreases a load
on the main compressor 11 when a difference between a high-pressure
side and a low-pressure side is great because ambient air
temperature is low during heating operation.
[0031] The auxiliary compression unit 20 includes: an auxiliary
fluid path 21, a sub-compressor 25, an inlet-side opening/closing
valve 23, an outlet-side opening/closing valve 24, a pressure
equalizing tank 27 and an oil return fluid path 28.
[0032] One side of the auxiliary fluid path 21 is connected to the
discharge side of the main compressor 11 and the other side thereof
is connected to the upstream side of the four-way valve 13.
[0033] The sub-compressor 25 is disposed on the auxiliary fluid
path 21, and compresses once again the refrigerant having been
compressed in the main compressor 11.
[0034] The inlet-side opening/closing valve 23 is disposed at an
inlet side of the auxiliary fluid path 21, and opens or closes the
auxiliary fluid path 21.
[0035] The outlet-side opening/closing valve 24 is disposed at an
outlet side of the auxiliary fluid path 21, and opens or closes the
auxiliary fluid path 21.
[0036] The pressure equalizing tank 27 is disposed on the
downstream side of the inlet-side opening/closing valve 23, and
temporarily receives the refrigerant compressed by the main
compressor 11. The pressure equalizing tank 27 reduces discharge
pulsation of the refrigerant being discharged from the main
compressor 11, and a problem resulted from a difference of mass
flow per unit time between the main compressor 11 and the
sub-compressor 25.
[0037] The oil return fluid path 28 responds to excessive oil
discharge in the main compressor 11. To do so, the oil return fluid
path 28 includes an oil return pipe 29 and a return pipe
opening/closing valve 30.
[0038] One side of the oil return fluid path 28 is installed at the
lower part of the pressure equalizing tank 27 and the other side
thereof is connected to an intake side of the main compressor 11
such that oil of the pressure equalizing tank 27 is returned to the
main compressor 11. Also, to have a convenience in installing oil
return fluid path 28, it is desirable that the oil return fluid
path 28 includes a capillary tube.
[0039] The oil return pipe 29 have one side connected with the
lower part of pressure equalizing tank 27 and the other side
connected to the intake side of the main compressor 11.
[0040] The return pipe opening/closing valve 30 is installed on the
oil return pipe 29, and opens or closes the oil return pipe 29.
[0041] Meanwhile, the inlet-side opening/closing valve 23 and the
outlet-side opening/closing valve 24 can be manually opened or
closed by measuring a pressure difference between the intake side
and the discharge side of the main compressor 11. However, it is
difficult for the user to measure and determine the pressure
difference and open or close the inlet-side opening/closing valve
23 and the outlet-side opening/closing valve 24 all the time.
Accordingly, in order to do this automatically, a intake-side
pressure sensor 12, a discharge-side pressure sensor 14 and a
control unit 31 are further included, preferably.
[0042] With reference to FIGS. 4 and 5, the intake-side pressure
sensor 12 is installed at the intake side of the main compressor 11
and transmits a signal to the control unit 31 by detecting the
pressure of the intake side of the main compressor 11.
[0043] The discharge-side pressure sensor 14 is installed at the
discharge side of the main compressor 11 and transmits a signal to
the control unit 31 by detecting the pressure of the discharge side
of the main compressor 11.
[0044] The control unit 31 is implemented in the form of MICOM
having a control program therein or the like, and controls the
opening or closing of the inlet-side opening/closing valve 23 and
the outlet-side opening/closing valve 24 by receiving signals of
the intake-side pressure sensor 12 and the discharge-side pressure
sensor 14. Here, the control unit 31 includes a pressure difference
calculating unit 33 for calculating the pressure difference between
the intake side and the discharge side of the main compressor 11,
preferably.
[0045] Hereinafter, the operation of the air conditioner in
accordance with the first embodiment illustrated in FIGS. 3 to 5
will be described. For reference, refrigerant flow is indicated by
the full line with the arrow and oil flow is indicated by the
dotted line with the arrow.
[0046] With reference to FIGS. 4 and 5, during heating operation,
the control unit 31 controls the four-way valve 13 such that the
refrigerant compressed in the main compressor 11 flows to the
indoor heat exchanger 17.
[0047] The refrigerant having flowed to the indoor heat exchanger
17 performs heating operation and then is decompressed and expanded
while passing the expansion valve 19.
[0048] The refrigerant having passed the expansion valve 19 absorbs
latent heat and is evaporated in the outdoor heat exchanger 15, and
is drawn into the main compressor 11 via the four-way valve 13.
[0049] The pressure difference calculating unit 33 calculates the
pressure difference between the intake side and the discharge side
through the signals transmitted from the intake-side pressure
sensor 12 and the discharge-side pressure sensor 14.
[0050] Here, when the pressure difference is small because ambient
air temperature is high, the refrigerant can be compressed by the
main compressor 11 without overload. Accordingly, the control unit
31 blocks the auxiliary fluid path 21 by closing the inlet-side
opening/closing valve 23 and the outlet-side opening/closing valve
24 such that compression of the refrigerant can be performed only
in the main compressor 11.
[0051] Meanwhile, when the pressure difference is great because
ambient air temperature is low, the overload may be on the main
compressor 11 when the compression of the refrigerant is performed
only by the main compressor 11. Accordingly, the control unit 31
opens the inlet-side opening/closing valve 23 and the outlet-side
opening/closing valve 24 and operates the sub-compressor 25 such
that the refrigerant can flow to the auxiliary fluid path 21. In
this case, part of the refrigerant discharged from the main
compressor 11 flows along the auxiliary fluid path 21 and is
temporarily received in the pressure equalizing tank 27.
[0052] The refrigerant received temporarily in the pressure
equalizing tank 27 is drawn into the sub-compressor 25 and is
condensed, then flows along the auxiliary fluid path 21 and joins
together with the refrigerant discharged from the main compressor
11, and then flows to the indoor heat exchanger 17 via the four-way
valve 13.
[0053] The refrigerant having performed the heating operation in
the indoor heat exchanger 17 is drawn into the main compressor 11
via the expansion valve 19, the outdoor heat exchanger 15 and the
four-way valve 13, and repeats compression and discharge
processes.
[0054] Meanwhile, if oil is accumulated to a certain degree, the
control unit 31 opens the return pipe opening/closing valve 30 so
as to open the oil return pipe 29.
[0055] If the oil return pipe 29 is opened, oil inside the pressure
equalizing tank 27 flows along the oil return pipe 29, is drawn
into the intake side of the main compressor 11, and is returned to
the inside of the main compressor 11.
[0056] Hereinafter, an air conditioner in accordance with a second
embodiment of the present invention will be described in detail.
FIG. 6 is a schematic view of an air conditioner in accordance with
the second embodiment of the present invention, FIG. 7 is a view
showing the operation of an auxiliary compression unit of FIG. 6,
and FIG. 8 is a control block diagram of the air conditioner of
FIG. 6. The same reference numerals are given to the same parts as
those in the aforementioned and illustrated construction for the
purpose of simplicity in description for the drawings, and detailed
descriptions therefor will be omitted.
[0057] In the first embodiment, the auxiliary compression unit 20
is operated when a pressure difference is great after the pressure
difference between the intake side and the discharge side of the
main compressor 11 is detected. On the other hand, in the second
embodiment, an auxiliary compression unit 20 is operated when
ambient air temperature is low after ambient air temperature is
detected instead of the pressure difference. As occasion demands,
after both the pressure difference and the ambient air temperature
are detected, on the basis of such results, the auxiliary
compression unit 20 can be operated.
[0058] To do so, the air conditioner in accordance with the second
embodiment includes an ambient air temperature sensor 40 instead of
the intake-side pressure sensor 12 and the discharge-side pressure
sensor 14 of the first embodiment. In addition, the air conditioner
of the second embodiment has a control unit 31 excluding the
pressure difference calculating unit 33 of the first embodiment.
The remaining construction except for this is the same and a
detailed description therefor will be omitted.
[0059] With reference to FIGS. 6 and 8, the ambient air temperature
sensor 50 is installed at one side of the outdoor heat exchanger
15, and transmits a signal to the control unit 31 by detecting
outside temperature.
[0060] Hereinafter, the operation of the air conditioner in
accordance with the second embodiment will be described. For
reference, refrigerant flow is indicated by the full line with the
arrow and oil flow is indicated by the dotted line with the
arrow.
[0061] During heating operation, the control unit 31 controls a
four-way valve 13 such that the refrigerant compressed in a main
compressor 11 flows to an indoor heat exchanger 17.
[0062] The refrigerant having flowed to the indoor heat exchanger
17 performs the heating operation, and is decompressed and expanded
while passing through an expansion valve 19.
[0063] The refrigerant having passed the expansion valve 19 absorbs
latent heat and is evaporated in the outdoor heat exchanger 15, and
is drawn into the main compressor 11 via the four-way valve 13.
[0064] The ambient air temperature sensor 50 detects the outside
temperature and transmits a signal to the control unit 31.
[0065] When ambient air temperature is high, compression of the
refrigerant can be performed by the main compressor 11 without
overload. Accordingly, the control unit 31 blocks an auxiliary
fluid path 21 by closing an inlet-side opening/closing valve 23 and
an outlet-side opening/closing valve 24.
[0066] Meanwhile, when the ambient air temperature is low, the
overload may be on the main compressor 11. Accordingly, the control
unit 31 opens the inlet-side opening/closing valve 23 and the
outlet-side opening/closing valve 24 such that the refrigerant can
flow to the auxiliary fluid path 21, and operates a sub-compressor
25. In this case, part of the refrigerant discharged from the main
compressor 11 flows along the auxiliary fluid path 21 and is
temporality received in a pressure equalizing tank 27.
[0067] The refrigerant temporarily received in the pressure
equalizing pipe 27 is drawn into the sub-compressor 25 and is
compressed, then flows along the auxiliary fluid path 21 and joins
together with the refrigerant discharged form the main compressor
11, and then flows to the indoor heat exchanger 17 via the four-way
valve 13.
[0068] The refrigerant having performed the heating operation in
the indoor heat exchanger 17 passes the expansion valve 19, the
outdoor heat exchanger 15, and the four-way valve 13, then is drawn
into the main compressor 11, and repeats compression and discharge
processes.
[0069] Meanwhile, if oil inside the pressure equalizing tank 27 is
accumulated to a certain degree, the control unit 31 opens a return
pipe opening/closing valve 30 so as to open an oil return pipe
29.
[0070] If the oil return pipe 29 is opened, the oil inside the
pressure equalizing tank 27 flows along the oil return pipe 29, is
drawn into an intake side of the main compressor 11, and is
returned to the inside of the main compressor 11.
[0071] As described so far, the air conditioner in accordance with
the embodiments of the present invention includes the auxiliary
compression unit 20 reducing the load on the main compressor 11
when ambient air temperature is low during heating operation.
Accordingly, since the load on the main compressor 11 decreases,
efficiency and reliability of the main compressor 11 are enhanced
and noises are reduced. In addition, an instrumental part such as a
bearing inside the main compressor 11 is not subject to abrasion
and high heat damage to a motor unit is prevented.
[0072] As the present invention may be embodied in several forms
without departing from the spirit or 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 spirit and scope as defined in the
appended claims, and therefore all changes and modifications that
fall within the metes and bounds of the claims, or equivalence of
such metes and bounds are therefore intended to be embraced by the
appended claims.
* * * * *