U.S. patent application number 12/096967 was filed with the patent office on 2009-12-24 for air conditioner.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. Invention is credited to Shinichi Kasahara, Tadafumi Nishimura.
Application Number | 20090314017 12/096967 |
Document ID | / |
Family ID | 38162931 |
Filed Date | 2009-12-24 |
United States Patent
Application |
20090314017 |
Kind Code |
A1 |
Nishimura; Tadafumi ; et
al. |
December 24, 2009 |
AIR CONDITIONER
Abstract
An air conditioner is provided with a refrigerant circuit,
refrigerant stagnation judging means, and an operation controller.
The refrigerant circuit is a circuit that includes a heat source
unit, a refrigerant communication pipe, an expansion mechanism, and
a utilization unit. A heat source unit and a utilization unit are
connected to the refrigerant fluid communication pipes. The heat
source unit has a compression mechanism and a heat source side heat
exchanger. The refrigerant stagnation judging means can judge
whether the refrigerant has stagnated inside the compression
mechanism. The operation controller performs a refrigerant
de-stagnation operation for eliminating stagnation of the
refrigerant in the case that the refrigerant stagnation judging
means has judged in advance that the refrigerant inside the
compression mechanism has stagnated when a refrigerant quantity
judging operation is carried out for judging the refrigerant
quantity inside the refrigerant circuit.
Inventors: |
Nishimura; Tadafumi; (Osaka,
JP) ; Kasahara; Shinichi; (Osaka, JP) |
Correspondence
Address: |
GLOBAL IP COUNSELORS, LLP
1233 20TH STREET, NW, SUITE 700
WASHINGTON
DC
20036-2680
US
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka
JP
|
Family ID: |
38162931 |
Appl. No.: |
12/096967 |
Filed: |
December 13, 2006 |
PCT Filed: |
December 13, 2006 |
PCT NO: |
PCT/JP2006/324806 |
371 Date: |
June 11, 2008 |
Current U.S.
Class: |
62/149 ;
62/468 |
Current CPC
Class: |
F25B 2500/19 20130101;
F25B 13/00 20130101; F25B 2700/04 20130101; F25B 2400/075 20130101;
F25B 2500/222 20130101; F25B 2500/28 20130101; F25B 45/00 20130101;
F25B 2313/0315 20130101; F25B 49/005 20130101; F25B 2400/01
20130101; F25B 2313/02743 20130101; F25B 2313/0233 20130101; F25B
2313/0253 20130101 |
Class at
Publication: |
62/149 ;
62/468 |
International
Class: |
F25B 45/00 20060101
F25B045/00; F25B 43/00 20060101 F25B043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2005 |
JP |
2005-363739 |
Claims
1. An air conditioner comprising: a refrigerant circuit having a
heat source unit having a compression mechanism and a heat source
side heat exchanger, a refrigerant communication pipe, the heat
source unit being connected thereto, an expansion mechanism, and a
utilization unit having a utilization side heat exchanger and being
connected to the refrigerant communication pipe; a refrigerant
stagnation judging device being configured to judge whether a
refrigerant is stagnant inside the compression mechanism; and an
operation controller performing a refrigerant de-stagnation
operation eliminating stagnation of the refrigerant in the case
that the refrigerant stagnation judging device has judged in
advance that the refrigerant is stagnant inside the compression
mechanism when a refrigerant quantity judging operation judging a
quantity of refrigerant inside the refrigerant circuit is carried
out.
2. The air conditioner as recited in claim 1, wherein the
refrigerant stagnation judging device makes a judgment on the basis
of a temperature inside the compression mechanism.
3. The air conditioner as recited in claim 1, wherein the
refrigerant stagnation judging device makes a judgment on the basis
of outside air temperature.
4. The air conditioner as recited in claim 1, wherein the
refrigerant stagnation judging device is connected to a network,
acquires weather information via the network, and makes a judgment
on the basis of the weather information.
5. The air conditioner as recited in claim 1, wherein the
refrigerant stagnation judging device makes a judgment on the basis
of a refrigerant stagnation interval in which the refrigerant is
predicted to stagnate readily inside the compression mechanism.
6. The air conditioner as recited in claim 5, wherein the operation
controller performs a control to drive the compression mechanism
for a first prescribed time as the refrigerant de-stagnation
operation.
7. The air conditioner as recited in claim 6, wherein a plurality
of the heat source units is present.
8. The air conditioner as recited in claim 7, wherein the
compression mechanism has a plurality of compressors.
9. The air conditioner as recited in claim 8, wherein the
refrigerant de-stagnation operation drives at least a compressor
that is not driven during the refrigerant quantity judgment
operation.
10. The air conditioner as recited in claim 8, wherein the
refrigerant de-stagnation operation is an operation in which the
operation controller operates all of the compressors one at a time
in sequence for a second prescribed time interval.
11. The air conditioner as recited in claim 1, further comprising a
heater configured to warm the compression mechanism, wherein the
refrigerant de-stagnation operation warms the compression mechanism
using the heater.
12. The air conditioner as recited in claim 10, wherein the
operation controller further performs an oil-return operation
immediately after the refrigerant de-stagnation operation.
13. The air conditioner as recited in claim 12, wherein the
oil-return operation controls the refrigerant that flows through
the refrigerant circuit so that the refrigerant flows inside the
pipes at or above a prescribed rate.
14. The air conditioner as recited in claim 1, wherein the
operation controller performs a control to drive the compression
mechanism for a first prescribed time as the refrigerant
de-stagnation operation.
15. The air conditioner as recited in claim 1, wherein a plurality
of the heat source units is present.
16. The air conditioner as recited in claim 1, wherein the
compression mechanism has a plurality of compressors.
17. The air conditioner as recited in claim 16, wherein the
refrigerant de-stagnation operation drives at least a compressor
that is not driven during the refrigerant quantity judgment
operation.
18. The air conditioner as recited in claim 16, wherein the
refrigerant de-stagnation operation is an operation in which the
operation controller operates all of the compressors one at a time
in sequence for a prescribed time interval.
19. The air conditioner as recited in claim 1, wherein the
operation controller further performs an oil-return operation
immediately after the refrigerant de-stagnation operation.
20. The air conditioner as recited in claim 19, wherein the
oil-return operation controls the refrigerant that flows through
the refrigerant circuit so that the refrigerant flows inside the
pipes at or above a prescribed rate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigerant circuit of an
air conditioner and an air conditioner provided therewith.
BACKGROUND ART
[0002] An example of a conventional refrigerant leak detector of a
refrigeration apparatus is disclosed in Patent Document 1. In this
refrigerant leak detector, a condensation refrigerant temperature
and an evaporative refrigerant temperature are keep at a fixed
value by using condensation refrigerant temperature adjustment
means and evaporative refrigerant temperature adjustment means, and
a refrigerant leak detection operation for detecting refrigerant
leaks in a refrigerating cycle is carried out using temperature
difference calculation means for comparing output signals of a
discharge refrigerant temperature detector and set values and
calculating a temperature difference. Therefore, the temperature of
the condensation refrigerant that flows through a condenser and the
temperature of the evaporative refrigerant that flow through an
evaporator are kept at a fixed value, whereby the discharge
refrigerant temperature under a suitable refrigerant quantity is
set to the set value. The set value and the output signal of the
discharge refrigerant temperature detector are compared, a judgment
is made that a refrigerant leak has not occurred when the value is
less than the set value, and a judgment is made that a refrigerant
leak has occurred when the value is higher than the set value.
<Patent Document 1>
[0003] Japanese Patent Application Publication No. H11-211292
DISCLOSURE OF THE INVENTION
Problems that the Invention is to Solve
[0004] However, with the technique of Patent Document 1, a risk is
presented that the predicted error of the refrigerant quantity will
increase because the refrigerant quantity that dissolves into the
refrigerating machine oil inside the compression mechanism
increases when the outside temperature is low. The refrigerant leak
detection error increases when the internal oil temperature is low
immediately after the compressor has started up and when only a
portion of the compressors are driven during a refrigerant leak
detection operation when a plurality of compressors are
present.
[0005] An object of the present invention is to solve the
stagnation of refrigerant in refrigeration machine oil inside a
compressor, and to minimize the prediction error of the refrigerant
quantity produced by the difference of solubility of the
refrigerant into the oil.
Means of Solving the Problems
[0006] The air conditioner according to a first aspect is provided
with a refrigerant circuit, a refrigerant stagnation judging means,
and an operation controller. The refrigerant circuit is a circuit
that includes a heat source unit, refrigerant communication pipes,
expansion mechanisms, and a utilization unit. The heat source unit
has a compression mechanism and a heat source side heat exchanger.
A heat source unit is connected to the refrigerant communication
pipes. The utilization unit has a utilization side heat source
exchanger and is connected to the refrigerant communication pipe.
The refrigerant stagnation judging means can judge whether the
refrigerant is stagnant inside the compression mechanism. The
operation controller performs a refrigerant de-stagnation operation
for eliminating stagnation of the refrigerant in the case that the
refrigerant stagnation judging means has judged in advance that the
refrigerant is stagnant inside the compression mechanism when a
refrigerant quantity judging operation is carried out for judging
the refrigerant quantity inside the refrigerant circuit.
[0007] In the air conditioner, the refrigerant stagnation judging
means makes a judgment in advance whether refrigerant is stagnant
in the refrigeration machine oil inside the compression mechanism
when the refrigerant quantity judgment operation is carried out.
The operation controller performs the refrigerant de-stagnation
operation when the refrigerant stagnation judging means judges that
refrigerant has stagnated in the refrigeration machine oil inside
the compression mechanism.
[0008] Therefore, in the air conditioner, the refrigerant quantity
judgment operation can be performed after refrigerant stagnation
has been eliminated in refrigeration machine oil inside the
compression mechanism. For this reason, the quantity of refrigerant
that dissolves into the refrigeration machine oil inside the
compression mechanism can be dramatically reduced and error in
predicting the refrigerant quantity can be reduced during the
refrigerant quantity judgment operation. A more precise refrigerant
quantity judgment operation is made possible because the
refrigerant stagnation can be eliminated in the refrigeration
machine oil inside the compression mechanism during the refrigerant
quantity judgment operation.
[0009] The air conditioner according to a second aspect is the air
conditioner according to the first aspect, wherein the refrigerant
stagnation judging means makes a judgment on the basis of the
temperature inside the compression mechanism.
[0010] In the air conditioner, the judgment of the refrigerant
stagnation judgment means is performed based on the temperature
inside the compression mechanism. Refrigerant more readily
stagnates in the refrigeration machine oil when the temperature
inside the compression mechanism is low. Therefore, it is possible
to determine that refrigerant has stagnated in the refrigeration
machine oil inside the compression mechanism when the temperature
inside the compression mechanism is low. For this reason, it is
possible to judge whether refrigerant has stagnated in the
refrigeration machine oil inside the compression mechanism on the
basis of the temperature inside the compression mechanism. The air
conditioner according to a third aspect is the air conditioner
according to the first aspect, wherein the refrigerant stagnation
judging means makes a judgment on the basis of the outside air
temperature.
[0011] In the air conditioner, the refrigerant stagnation judging
means judges based on the temperature of the outside air. The
refrigerant readily becomes stagnant in the refrigeration machine
oil when the temperature inside the compression mechanism is low.
Therefore, the temperature inside the compression mechanism can be
predicted because the temperature of the outside air can be
measured. For this reason, the judgment that refrigerant has
stagnated in the refrigeration machine oil inside the compression
mechanism is made possible when the temperature inside the
compression mechanism can be predicted to be low. Judgment as to
whether the refrigerant has stagnated in the refrigeration machine
oil inside the compression mechanism is thereby made possible.
[0012] The air conditioner according to a fourth aspect is the air
conditioner according to the first aspect, wherein the refrigerant
stagnation judging means makes a judgment on the basis of weather
information.
[0013] In the air conditioner, the refrigerant stagnation judging
means makes a judgment based on weather information obtained via a
network connected to the refrigerant stagnation judgment means.
Therefore, the outside temperature can be acquired from the weather
information, and the temperature inside the compression mechanism
can be predicted. It is accordingly possible to determine that the
refrigerant has stagnated in the refrigeration machine oil inside
the compression mechanism when the temperature inside the
compression mechanism can be predicted to be low. Judgment as to
whether refrigerant has stagnated in the refrigeration machine oil
inside the compression mechanism is thereby made possible.
[0014] The air conditioner according to a fifth aspect is the air
conditioner according to the first aspect, wherein the refrigerant
stagnation judgment means makes judgment on the basis of a
refrigerant stagnation interval in which the refrigerant is
predicted to readily stagnate inside the compression mechanism.
[0015] In the air conditioner, the refrigerant stagnation judging
means makes a judgment based on a time interval that has been set
in advance. The refrigerant readily stagnates in the refrigeration
machine oil when the temperature inside the compression mechanism
is low. The judgment is made by establishing a time interval in
which the temperature inside the compression mechanism is predicted
to be low. Therefore, the user sets the time interval in which the
temperature inside the compression mechanism is predicted to be
low, whereby the refrigerant stagnation can be predicted without
measuring the temperature inside the compression mechanism. It is
thereby possible to judge whether the refrigerant has stagnated in
the refrigeration machine oil inside the compression mechanism.
Also, production costs can be reduced because a temperature sensor
or the like no longer needs to be installed.
[0016] The air conditioner according to a sixth aspect is the air
conditioner according to any of the first to fifth aspects, wherein
the operation controller performs a control for driving the
compression mechanism for a first prescribed time as the
refrigerant de-stagnation operation. In the air conditioner, the
refrigerant de-stagnation operation is a warm-up operation that is
performed by driving a compressor for a first prescribed length of
time. Therefore, in the refrigerant de-stagnation operation, a
compressor is operated for a first prescribed length of time,
whereby the interior of the compression mechanism can be warmed up.
For this reason, refrigerant stagnation in the refrigeration
machine oil inside the compression mechanism can be eliminated.
[0017] The air conditioner according to a seventh aspect is the air
conditioner according to any of the first to sixth aspects, wherein
a plurality of the heat source units is present.
[0018] In the air conditioner, a plurality of heat source units is
present. Therefore, the service life of the entire system can be
extended without placing the load exclusively on a single unit even
during low-load operation, because the heat source units in the
system can be placed in a rotation and driven at fixed intervals of
time one unit at a time.
[0019] The air conditioner according to an eighth aspect is the air
conditioner according to any of the first to seventh aspects,
wherein the compression mechanism has a plurality of compressors.
In the air conditioner, the compression mechanism has a plurality
of compressors. Therefore, all of the heat source units can be
continuously operated and the pooling of refrigerant and oil in the
refrigerant circuit can be prevented to the extent possible even
when the operating load of the utilization unit has been reduced
because the capacity of the compression mechanism can be varied by
controlling the number of compressors. The remaining compressors
can handle the load even if one of the compressors malfunctions.
For this reason, a complete stoppage of the air conditioner can be
avoided.
[0020] The air conditioner according to a ninth aspect is the air
conditioner according to the eighth aspect, wherein the refrigerant
de-stagnation operation is an operation for driving at least a
compressor that is not driven during the refrigerant quantity
judgment operation.
[0021] In the air conditioner, in relation to the compressors that
are used during pre-operation, at least a compressor that is not
driven when the refrigerant quantity judging is driven because the
compressors that are driven to judge the refrigerant quantity can
be sufficiently warmed at the time of the refrigerant quantity
judging operation when a plurality of compressor is present.
[0022] Therefore, the energy that is used can be reduced because
all of the compressors are not required to operate. Also, the time
required for the refrigerant de-stagnation operation can be
reduced.
[0023] The air conditioner according to a tenth aspect is the air
conditioner according to the eighth aspect, wherein the refrigerant
de-stagnation operation is an operation in which the operation
controller operates all of the compressors one at a time in
sequence for a second prescribed time interval.
[0024] In the air conditioner, all of the compressors are driven
for a second prescribed time period in a single-unit rotation when
a plurality of compressors is present. It is difficult to cause all
of the compressors to operate at the same time at the time of the
refrigerant de-stagnation operation due to a low load because the
refrigeration operation is carried out when the outside temperature
is low. For this reason, the units are operated one at a time for a
second prescribed time interval, whereby all of the compressors can
be operated in advance.
[0025] The air conditioner according to an eleventh aspect is the
air conditioner according to the first aspect, further comprising a
heater for warming the compression mechanism. The refrigerant
de-stagnation operation is an operation for warming the compression
mechanism using the heater.
[0026] In the air conditioner, the refrigerant de-stagnation
operation can be performed by warming the compression mechanism
using a heater. Therefore, refrigerant stagnation can be eliminated
without driving a compressor. For this reason, the time that a
compressor is driven can be reduced and the service life of a
compressor can be extended because a compressor is not required to
be driven during the refrigerant de-stagnation operation.
[0027] The air conditioner according to a twelfth aspect is the air
conditioner according to any of the first to eleventh aspects,
wherein the operation controller further performs an oil-return
operation immediately after the refrigerant de-stagnation
operation. The oil-return operation is an operation for returning
oil pooled in the refrigerant circuit to the compression
mechanism.
[0028] In the air conditioner, an oil-return operation is further
carried out after the refrigerant de-stagnation operation.
Therefore, oil that is pooled in the refrigerant circuit can be
returned to the compression mechanism by further carrying out an
oil-return operation. The refrigerant quantity judgment operation
can accordingly be carried out with greater precision. The air
conditioner according to a thirteenth aspect is the air conditioner
according to the twelfth aspect, wherein the oil-return operation
is an operation for controlling the refrigerant that flows through
the refrigerant circuit so that the refrigerant flows inside the
pipes at or above a prescribed rate.
[0029] In the air conditioner, the oil-return operation is an
operation for controlling the refrigerant so that the refrigerant
flows inside the pipes at or above a prescribed rate. Therefore,
oil pooled in the refrigerant circuit can be reliably returned to
the compression mechanism. The refrigerant quantity judgment
operation can accordingly be carried out with greater
precision.
EFFECT OF THE INVENTION
[0030] In the air conditioner according to the first aspect, the
refrigerant quantity judging operation can be carried out after the
stagnation of refrigerant has been eliminated in the refrigeration
machine oil inside the compression mechanism. The quantity of
refrigerant that has dissolved in the refrigeration machine oil
inside the compression mechanism can accordingly be reduced to the
extent possible at the time of the refrigerant quantity judging
operation, and the prediction error of the refrigerant quantity can
be reduced. A more precise refrigerant quantity judgment operation
is made possible because the refrigerant stagnation can be
eliminated in the refrigeration machine oil inside the compression
mechanism during the refrigerant quantity judgment operation.
[0031] In the air conditioner according to the second aspect, the
refrigerant can be judged to have stagnated in the refrigeration
machine oil inside the compression mechanism when the temperature
inside the compression mechanism is low. For this reason, the
decision as to whether the refrigerant has stagnated in the
refrigeration machine oil inside the compression mechanism can be
made on the basis of the temperature inside the compression
mechanism. In the air conditioner according to the third aspect,
the temperature inside the compression mechanism can be predicted
because the temperature of the outside air can be measured.
Accordingly, it can be judged that the refrigerant has stagnated in
the refrigeration machine oil inside the compression mechanism when
the temperature inside the compression mechanism can be predicted
to be low. It can thereby be judged whether the refrigerant has
stagnated in the refrigeration machine oil inside the compression
mechanism.
[0032] In the air conditioner according to the fourth aspect, the
temperature of the outside air can be acquired from weather
information and the temperature inside the compression mechanism
can be predicted. Accordingly, it can be judged that the
refrigerant has stagnated in the refrigeration machine oil inside
the compression mechanism when the temperature inside the
compression mechanism can be predicted to be low. It can thereby be
judged whether the refrigerant has stagnated in the refrigeration
machine oil inside the compression mechanism. In the air
conditioner according to the fifth aspect, a user sets a length of
time in which the temperature inside the compression mechanism is
predicted to be low, whereby refrigerant stagnation can be
predicted without measuring the temperature inside the compression
mechanism. It is thereby possible to judge whether refrigerant has
stagnated in the refrigeration machine oil inside the compression
mechanism. Production costs can be reduced because there is no
longer a need to install a temperature sensor or the like. In the
air conditioner according to the sixth aspect, the interior of the
compression mechanism can be warmed by operating a compressor for a
first prescribed length of time. For this reason, refrigerant
stagnation in the refrigeration machine oil inside the compression
mechanism can be eliminated.
[0033] In the air conditioner according to the seventh aspect, the
service life of the entire system can be extended without placing
the load exclusively on a single unit even during low-load
operation because the heat source units in the system can be placed
in a rotation and driven at fixed intervals of time one unit at a
time.
[0034] In the air conditioner according to the eighth aspect, all
of the heat source units can be operated continuously and the
pooling of refrigerant and oil in the refrigerant circuit can be
prevented to the extent possible even when the operating load of
the utilization units is low, because the capacity of the
compression mechanism can be varied by controlling the number of
compressors. The remaining compressors can handle the load even if
one of the compressors malfunctions. For this reason, a complete
stoppage of the air conditioner can be avoided.
[0035] In the air conditioner according to the ninth aspect, the
energy that is used can be reduced because all of the compressors
are not required to operate. Also, the time required for the
refrigerant de-stagnation operation can be reduced.
[0036] In the air conditioner according to the tenth aspect, all of
the compressors can be driven in advance by operating the
compressors for a second prescribed time interval one unit at a
time. In the air conditioner according to the eleventh aspect,
stagnation of the refrigerant can be eliminated without driving a
compressor. The time a compressor is driven can be reduced and the
service life of the compressors can be extended because a
compressor is not required to be driven during the refrigerant
de-stagnation operation.
[0037] In the air conditioner according to the twelfth aspect, oil
that has pooled in the refrigerant circuit can be returned to the
compression mechanism by further performing an oil-return
operation. The refrigerant quantity judging operation can
accordingly be carried out with greater precision.
[0038] In the air conditioner according to the thirteenth aspect,
oil that has pooled inside the refrigerant circuit can be reliably
returned to the compression mechanism. The refrigerant quantity
judging operation can accordingly be carried out with greater
precision.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a schematic diagram of a refrigerant circuit of an
air conditioner related to an embodiment of the present
invention;
[0040] FIG. 2 is a flowchart showing the flow of a refrigerant leak
detection operation related to an embodiment of the present
invention;
[0041] FIG. 3 is a flowchart showing the flow of an automatic
refrigerant charging operation related to an embodiment of the
present invention;
[0042] FIG. 4 is a flowchart showing the flow of a refrigerant
quantity judging preparatory operation related to an embodiment of
the present invention;
[0043] FIG. 5 is a flowchart showing the flow of a refrigerant
de-stagnation operation related to an embodiment of the present
invention;
[0044] FIG. 6 is a flowchart showing the flow of an oil-return
operation related to an embodiment of the present invention;
and
[0045] FIG. 7 is a schematic diagram of a weather information
acquisition network of an air conditioner related a modified
example (E) of an embodiment of the present invention.
DESCRIPTION OF THE REFERENCE SYMBOLS
[0046] 1 Air conditioner [0047] 2a to 2c Heat source units [0048]
3a, 3b, . . . Utilization units [0049] 4, 5 Refrigerant
communication pipes [0050] 6a to 6c Operation controllers [0051] 8a
to 8c Refrigerant stagnation judging means [0052] 21a to 21c
Compression mechanisms [0053] 22a to 22c, 27a to 27c, 28a to 28c
Compressors [0054] 24a to 24c Heat source side heat exchangers
[0055] 29a to 29c Heat source side expansion valves [0056] 31a,
31b, . . . Utilization side expansion valves [0057] 32a, 32c, . . .
Utilization side heat exchangers
BEST MODE FOR CARRYING OUT THE INVENTION
(1) Configuration of the Air Conditioner
[0058] FIG. 1 shows a schematic diagram of refrigerant circuit of
an air conditioner 1 related to a first embodiment of the present
invention. The air conditioner 1 is used for conditioning the air
of a building or the like, and has a configuration in which a
plurality (three, in the present embodiment) of air-cooled heat
source units 2a to 2c and numerous utilization units 3a, 3b, . . .
are connected in parallel to a liquid refrigerant communication
pipe 4 and a gas refrigerant communication pipe 5, respectively. In
this case, only two utilization units 3a and 3b are shown. The
plurality of heat source units 2a to 2c are provided with
compression mechanisms 21a to 21c that each have single
variable-capacity compressors 22a to 22c and a plurality (two, in
the present embodiment) fixed-capacity compressors 27a to 27c, and
28a to 28c.
[0059] The utilization units 3a, 3b, . . . are mainly composed of
utilization side expansion valves 31a, 31b, . . . , utilization
side heat exchangers 32a, 32b, . . . , and pipes that connect
thereto, respectively. In the present embodiment, the utilization
side expansion valves 31a, 31b, . . . are electrically driven
expansion valves connected to the liquid refrigerant communication
pipe 4 side (hereinafter referred to as a liquid side) of the
utilization side heat exchangers 32a, 32b, . . . in order to adjust
the refrigerant pressure, adjust the refrigerant flow rate, and
perform other operations. In the present embodiment, the
utilization side heat exchangers 32a, 32b, . . . are cross-fin tube
heat exchangers and are devices for exchanging heat with indoor
air. In the present embodiment, the utilization units 3a, 3b, . . .
are provided with a indoor fan (not shown) for taking indoor air
into the units and discharging air, and can exchange heat between
the indoor air and the refrigerant that flows through the
utilization side heat exchangers 32a, 32b, . . . .
[0060] The heat source units 2a to 2c are mainly composed of
compression mechanisms 21a to 21c, four-way switching valves 23a to
23c, heat source side heat exchangers 24a to 24c, liquid side stop
valves 25a to 25c, gas side stop valves 26a to 26c, heat source
side expansion valves 29a to 29c, and pipes that connect thereto,
respectively. In the present embodiment, the heat source side
expansion valves 29a to 29c are electrically driven expansion
valves connected to the liquid refrigerant communication pipe 4
side (hereinafter referred to as a liquid side) of the heat source
side expansion valves 29a to 29c in order to adjust the refrigerant
pressure, adjust the refrigerant flow rate, and perform other
operations. The compression mechanisms 21a to 21c have
variable-capacity compressors 22a to 22c, two fixed-capacity
compressors 27a to 27c and 28a to 28c, and an oil separator (not
shown).
[0061] The compressors 22a to 22c, 27a to 27c, and 28a to 28c are
devices for compressing refrigerant gas that has been taken in,
and, in the present embodiment, are composed of a single
variable-capacity compressor in which the operating capacity can be
changed by inverter control, and two fixed-capacity
compressors.
[0062] The four-way switching valves 23a to 23c are valves for
switching the direction of the flow of the refrigerant when a
switch is made between cooling and heating operations; during
cooling operation, are capable of connecting the compression
mechanisms 21a to 21c and the gas refrigerant communication pipe 5
side (hereinafter referred to as gas side) of the heat source side
heat exchangers 24a to 24c, and connecting a suction side of the
compressors 21a to 21c and the gas refrigerant communication pipe 5
(see the solid lines of the four-way switching valves 23a to 23c of
FIG. 1); and, during heating operation, are capable of connecting
the outlets of the compression mechanisms 21a to 21c and the gas
refrigerant communication pipe 5, and connecting the suction side
of the compression mechanisms 21a to 21c and the gas side of the
heat source side heat exchangers 24a to 24c (see the broken lines
of the four-way switching valves 23a to 23c of FIG. 1).
[0063] In the present embodiment, the heat source side heat
exchangers 24a to 24c are cross-fin tube heat exchangers and are
devices for exchanging heat between the refrigerant and outside air
as a heat source. In the present embodiment, the heat source units
2a to 2c are provided with an outdoor fan (not shown) for taking
outdoor air into the units and discharging air, and can exchange
heat between the outdoor air and the refrigerant that flows through
the heat source side heat exchangers 24a to 24c.
[0064] The liquid side stop valves 25a to 25c and the gas side stop
valves 26a to 26c of the heat source units 2a to 2c are connected
in parallel to the liquid refrigerant communication pipe 4 and the
gas refrigerant communication pipe 5. The liquid refrigerant
communication pipe 4 is connected between the liquid side of the
utilization side heat exchangers 32a, 32b, . . . of the utilization
units 3a, 3b, . . . and the liquid side of the heat source side
heat exchangers 24a to 24c of the heat source units 2a to 2c. The
gas refrigerant communication pipe 5 is connected between the gas
side of the utilization side heat exchangers 32a, 32b, . . . of the
utilization units 3a, 3b, . . . and the four-way switching valves
23a to 23c of the heat source units 2a to 2c.
[0065] The air conditioner 1 is further provided with refrigerant
stagnation judging means 8a to 8c and operation controllers 6a to
6c. The refrigerant stagnation judging means 8a to 8c judges
whether refrigerant has stagnated inside the compression mechanisms
21a to 21c. The operation controllers 6a to 6c carry out in advance
a refrigerant de-stagnation operation for resolving stagnation of
the refrigerant when the refrigerant has stagnated in the
compression mechanisms 21a to 21c when a refrigerant quantity
judging operation for judging the of refrigerant quantity inside
the refrigerant circuit 7 is carried out. In the present
embodiment, the refrigerant stagnation judging means and the
operation controllers 6a to 6c are housed in the heat source units
2a to 2c. Operation control such as that described above can be
performed using only the operation controller (6a, in this case) of
the heat source unit (2a, in this case) set as the parent device.
The operation controllers (6b and 6c, in this case) of the heat
source units (2a and 2b, in this case) set as the other subordinate
devices can send the operating state of the compression mechanism
and other devices and detection data in the various sensors to the
parent operation controller 6a, and can function so as to send
operation and stop commands to the compression mechanism and other
devices via commands from the parent operation controller 6a. In
this case, temperature sensors 61a to 61c (see FIG. 1) are
provided, the temperature of the outside air is measured by the
temperature sensors, and the temperature data is sent to the parent
operation controller 6a. In the operation controller 6a, a judgment
is made whether to perform the refrigerant de-stagnation
operation.
(2) Operation of the Air Conditioner
[0066] Next, the operation of the air conditioner 1 will be
described with reference to FIG. 1.
<Normal Operation>
(Cooling Operation)
[0067] The cooling operation will be described first. During the
cooling operation, the four-way switching valves 23a to 23c in all
of the heat source units 2a to 2c are in the state indicated by the
solid lines in FIG. 1, i.e., the discharge side of the compression
mechanisms 21a to 21c is connected to the gas side of the heat
source side heat exchangers 24a to 24c, and the suction side of the
compression mechanisms 21a to 21c is connected to the gas side of
the utilization side heat exchangers 32a, 32b, . . . via the gas
refrigerant communication pipe 5. Also, the liquid side stop valves
25a to 25c and the gas side stop valves 26a to 26c are opened and
the opening position of the utilization side expansion valves 31a,
31b, . . . is adjusted so as to reduce the pressure of the
refrigerant.
[0068] In this state of the refrigerant circuit 7 of the air
conditioner 1, the refrigerant gas is taken into the compression
mechanisms 21a to 21c and compressed when the outdoor fans (not
shown) of the heat source units 2a to 2c and the indoor fans (not
shown) and the compression mechanisms 21a to 21c of the utilization
units 3a, 3b, . . . are started up, whereupon the refrigerant gas
is sent to the heat source side heat exchangers 24a to 24c via the
four-way switching valves 23a to 23c, exchanges heat with the
outside air, and is condensed. The condensed refrigerant liquid is
merged with the liquid refrigerant communication pipe 4 and sent to
the utilization units 3a, 3b, . . . The refrigerant fluid sent to
the utilization units 3a, 3b, . . . is reduced in pressure by the
utilization side expansion valves 31a, 31b, . . . , is then
subjected to heat exchange with indoor air in the utilization side
heat exchangers 32a, 32b, . . . , and is then caused to evaporate.
The evaporated refrigerant gas is sent through the gas refrigerant
communication pipe 5 to the heat source units 2a to 2c side. The
refrigerant gas that flows through the gas refrigerant
communication pipe 5 passes through the four-way switching valves
23a to 23c of the heat source units 2a to 2c, and is thereafter
taken into the compression mechanisms 21a to 21c again. The cooling
operation is carried out in this manner.
(Heating Operation)
[0069] The heating operation will be described next. During the
heating operation, the four-way switching valves 23a to 23c in all
of the heat source units 2a to 2c are in the state indicated by the
broken lines in FIG. 1, i.e., the discharge side of the compression
mechanisms 21a to 21c is connected to the gas side of the
utilization side heat exchangers 32a, 32b, . . . via the gas
refrigerant communication pipe 5 and the suction side of the
compression mechanisms 21a to 21c is connected to the gas side of
the heat source side heat exchangers 24a to 24c. Also, the liquid
side stop valves 25a to 25c and the gas side stop valves 26a to 26c
are opened and the opening position of the heat source side
expansion valves 29a to 29c is adjusted so as to reduce the
pressure of the refrigerant.
[0070] In this state of the refrigerant circuit 7 of the air
conditioner 1, the refrigerant gas is taken into the compression
mechanisms 21a to 21c and compressed when the outdoor fans (not
shown) of the heat source units 2a to 2c and the indoor fans (not
shown) and the compression mechanisms 21a to 21c of the utilization
units 3a, 3b, . . . are started up, whereupon the refrigerant gas
is merged with the gas refrigerant communication pipe 5 via the
four-way switching valves 23a to 23c of the heat source units 2a to
2c and sent to the utilization units 3a, 3b, . . . side. The
refrigerant gas sent to the utilization units 3a, 3b, . . . ,
exchanges heat with the indoor air via the utilization side heat
exchangers 32a, 32b, . . . , and is condensed. The condensed
refrigerant is merged with the liquid refrigerant communication
pipe 4 via the utilization side expansion valves 31a, 31b, . . . ,
and is sent to the heat source units 2a to 2c side. The refrigerant
liquid that flows through the liquid refrigerant communication pipe
4 is made to exchange heat with the outside air via the heat source
side heat exchangers 24a to 24c of the heat source units 2a to 2c,
and is caused to evaporate. The evaporated refrigerant gas is taken
into the compression mechanisms 21a to 21c again via the four-way
switching valves 23a to 23c of the heat source units 2a to 2c. The
heating operation is carried out in this manner.
<Refrigerant Quantity Judging Operation>
[0071] Next, the refrigerant quantity judging operation will be
described. The refrigerant quantity judging operation includes a
refrigerant leakage detection operation and an automatic
refrigerant charging operation.
(Refrigerant Leak Detection Operation)
[0072] The refrigerant leak detection operation, which is one of
the refrigerant quantity judging operation, will described with
reference to FIGS. 1 and 2. Here, FIG. 2 is a flowchart of the
refrigerant leak detection operation.
[0073] As an example, a case will be described in which operation
is periodically (e.g., once per month, when load processing is not
required in the air conditioning space, or at another time)
switched to the refrigerant leak detection operation, which is a
refrigerant quantity judging operation, during cooling operation or
heating operation in normal operation, whereby detection is
performed to determine whether refrigerant inside the refrigerant
circuit 7 has leaked to the exterior due to an unknown cause.
[0074] First, in step S1, a refrigerant quantity judging
preparatory operation is carried out prior to refrigerant leak
detection operation. The refrigerant quantity judging preparatory
operation will be described later.
[0075] Next, in step S2, a judgment is made whether an operation in
normal operation such as the cooling operation or the heating
operation described above has continued for a fixed length of time
(e.g., one month), and the process proceeds to the next step S2
when an operation in normal operation has continued for a fixed
length of time.
[0076] In step S3, when an operation in normal operation has
continued for a fixed length of time, the refrigerant circuit 7
enters a state in which the four-way switching valves 23a to 23c of
the heat source units 2a to 2c are in the state indicated by the
solid lines of FIG. 1, the utilization side expansion valves 31a,
31b, . . . of the utilization units 3a, 3b, . . . are opened, the
compression mechanisms 21a to 21c and the outdoor fan (not shown)
are actuated, and a cooling operation is forcibly carried out in
all of the utilization units 3a, 3b, . . . .
[0077] In step S4, condensation pressure control by an outdoor fan,
overheating control by the utilization side expansion valves 31a,
31b, . . . , and evaporation pressure control by the compression
mechanisms 21a to 21c are carried out and the state of the
refrigerant that circulates inside the refrigerant circuit 7 is
stabilized.
[0078] In step S5, subcooling degree is detected at the outlets of
the heat source side heat exchangers 24a to 24c.
[0079] In step S6, the subcooling degree detected in step S5 is
used to judge whether the refrigerant quantity is adequate. The
adequacy of the refrigerant quantity charged in the refrigerant
circuit 7 can be judged when subcooling degree is detected in step
S5 by using the subcooling degree of the refrigerant at the outlets
of the heat source side heat exchangers 24a to 24c without relation
to the mode of the utilization units 3a, 3b, . . . and the length
of the liquid refrigerant communication pipe 4 and gas refrigerant
communication pipe 5.
[0080] The refrigerant quantity in the heat source side heat
exchangers 24a to 24c is at a low level when the quantity of
additional refrigerant charging is low and the required refrigerant
quantity is not attained (specifically indicating that the
subcooling degree detected in step S5 is less than an subcooling
degree that corresponds to the refrigerant quantity that is
required for condensation pressure of the heat source side heat
exchangers 24a to 24c). It is judged that there is no refrigerant
leakage when the subcooling degree detected in step S5 is
substantially the same degree (e.g., the difference between the
detected subcooling degree and the target subcooling degree is less
than a prescribed degree) as the target subcooling degree, and the
refrigerant leak detection operation is ended.
[0081] On the other hand, when the subcooling degree detected in
step S5 is a degree that is less than the target subcooling degree
(e.g., the difference between the detected subcooling degree and
the target subcooling degree is a prescribed degree or greater), it
is judged that refrigerant leakage has occurred. The process
proceeds to the processing of step S7, and a warning that provides
notification that refrigerant leakage has been detected is
displayed, whereupon the refrigerant leak detection operation is
ended.
(Automatic Refrigerant Charging Operation)
[0082] The automatic refrigerant charging operation as one of the
refrigerant quantity judging operation will described with
reference to FIGS. 1 and 3. Here, FIG. 3 is a flowchart of the
automatic refrigerant charging operation.
[0083] As an example, a case will be described in which a
refrigerant circuit 7 is assembled at the installation site by
connecting the utilization units 3a, 3b, . . . and the heat source
units 2a to 2c filled with refrigerant in advance are connected by
way of the liquid refrigerant communication pipe 4 and gas
refrigerant communication pipe 5, and refrigerant that is lacking
is thereafter added and charged in the refrigerant circuit 7 in
accordance with the length of the liquid refrigerant communication
pipe 4 and the gas refrigerant communication pipe 5.
[0084] First, the liquid side stop valves 25a to 25c and the gas
side stop valves 26a to 26c of the heat source units 2a to 2c are
opened, and the refrigerant charged in advance in the heat source
units 2a to 2c is filled into the refrigerant circuit 7.
[0085] Next, the person who carries out the refrigerant charging
work sends a command to carry out an automatic refrigerant charging
operation, which is one of the refrigerant quantity judging
operation, via remote control or directly to utilization side
controllers (not shown) of the utilization units 3a, 3b, . . . or
to the operation controllers 6a to 6c of the heat source units 2a
to 2c, whereupon the automatic refrigerant charging operation is
carried out in the sequence of step S11 to step S14.
[0086] In step S11, the refrigerant quantity judging preparatory
operation is carried out prior to the automatic refrigerant
charging operation. The refrigerant quantity judging preparatory
operation will be described later.
[0087] In step S12, when a command has been issued for the
automatic refrigerant charging operation to begin, the refrigerant
circuit 7 enters a state in which the four-way switching valves 23a
to 23c of the heat source units 2a to 2c are in the state indicated
by the solid lines of FIG. 1, the utilization side expansion valves
31a, 31b, . . . of the utilization units 3a, 3b, . . . are opened,
the compression mechanisms 21a to 21c and the outdoor fan (not
shown) are actuated, and a cooling operation is forcibly carried
out in all of the utilization units 3a, 3b, . . . .
[0088] In step S13, condensation pressure control by an outdoor
fan, overheating control by the utilization side expansion valves
31a, 31b, . . . , and evaporation pressure control by the
compression mechanisms 21a to 21c are carried out and the state of
the refrigerant that circulates inside the refrigerant circuit 7 is
stabilized.
[0089] In step S14, subcooling degree is detected at the outlets of
the heat source side heat exchangers 24a to 24c.
[0090] In step S15, the subcooling degree detected in step S14 is
used to judge whether the amount of refrigerant is adequate.
Specifically, when the subcooling degree detected in step S14 is
less than the target subcooling degree and refrigerant charging is
not completed, the processing of step S13 and step S14 is repeated
until the subcooling degree reaches the target subcooling
degree.
[0091] The automatic refrigerant charging operation can be carried
out when refrigerant is charged during a test operation after
onsite installation, and can also be used to perform additional
refrigerant charging when the quantity of refrigerant charged in
the refrigerant circuit 7 has been reduced due to refrigerant
leakage or the like.
<Refrigerant Quantity Judging Preparatory Operation>
[0092] In the refrigerant quantity judging operation described
above, refrigerant stagnation judging means 8a to 8c judges that
the refrigerant has stagnated inside the compression mechanisms 21a
to 21c when the temperature detected by temperature sensors 61a to
61c is lower than a prescribed temperature, and sends a signal
indicating the stagnation of the refrigerant to the operation
controller 6a. The operation controller 6a, which has received a
signal from the refrigerant stagnation judging means 8a to 8c,
performs--a control (refrigerant de-stagnation operation)
preliminarily so that the compressors 22a to 22c, 27a to 27c, and
28a to 28c are sufficiently warmed.
[0093] In FIG. 4, the operation controller 6a judges in step S21
whether the temperature inside the compression mechanisms 21a to
21c measured by the temperature sensors 61a to 61c is lower than a
prescribed temperature. When the compressor temperature is lower
than the prescribed temperature, the process proceeds to step S22,
and when the temperature is not lower than the prescribed
temperature, the process proceeds to step S23. The refrigerant
de-stagnation operation is carried out in step S22 and the process
proceeds to step S23. An oil-return operation is carried out in
step S23. When the oil-return operation is completed, the process
proceeds to step S2 in the case that the refrigerant quantity
judging operation is a refrigerant leak detection operation, and
the process proceeds to step S12 in the case that the refrigerant
quantity judging operation is an automatic refrigerant charging
operation.
(Refrigerant De-Stagnation Operation)
[0094] Here, the refrigerant de-stagnation operation of step S22
described above will be described. The operation controller 6a
issues a drive command to all of the compression mechanisms 21a to
21c of the heat source units 2a to 2c when a signal is received
from the refrigerant stagnation judging means 8a to 8c. In relation
to the heat source units 2b and 2c, however, the operation
controllers 6b and 6c, which are subordinate devices, receive the
commands of the parent operation controller 6a and issue a drive
command to the compression mechanisms 21b and 21c.
[0095] In FIG. 5, the compressors 22a to 22c are driven in step S31
and the process proceeds to step S32. In step S32, the compressors
22a to 22c are stopped 15 minutes after step S31, the compressors
27a to 27c are driven, and the process proceeds to step S33. In
step S33, the compressors 27a to 27c are stopped 15 minutes after
step S32, the compressors 28a to 28c are driven, and the process
proceeds to step S34. In step S34, the compressors 28a to 28c are
stopped 15 minutes after step S33, and the refrigerant
de-stagnation operation is ended.
(Oil-Return Operation)
[0096] The oil-return operation of step S23 is carried out when the
refrigerant de-stagnation operation described above is ended, or
when the temperature of the compressors in step S21 is higher than
a prescribed temperature. Here, the oil-return operation will be
described with reference to FIG. 6.
[0097] In step S41, the operation controller 6a issues a command to
drive one of the compressors (i.e., compressors 22a to 22c) of the
heat source units 2a to 2c. In relation to the heat source units 2b
and 2c, however, the operation controllers 6b and 6c, which are
subordinate devices, receive the commands of the parent operation
controller 6a and the subordinate operation controllers 6b and 6c
issue a drive command to the compression mechanisms 22b and 22c.
When step S41 is ended, the process proceeds to step S42. In step
S42, the operation controller 6a issues a command to stop after the
compressors 22a to 22c have been driven for 5 minutes. The oil
pooled in the refrigerant circuit 7 can thereby be returned to the
compression mechanisms 21a to 21c.
<Characteristics>
[0098] (1)
[0099] In the air conditioner 1, the refrigerant stagnation judging
means makes a judgment in advance whether refrigerant has stagnated
in the refrigeration machine oil inside compressors 22a to 22c, 27a
to 27c, and 28a to 28c when the refrigerant quantity judgment
operation is carried out. The operation controller 6a performs the
refrigerant de-stagnation operation when the refrigerant stagnation
judging means judges that refrigerant has stagnated in the
refrigeration machine oil inside the compression mechanisms 21a to
21c. Therefore, in the air conditioner 1, the judgment operation
can be performed after refrigerant pooling has been eliminated in
the refrigeration machine oil inside the compression mechanisms 21a
to 21c. For this reason, the refrigerant quantity that dissolves
into the refrigeration machine oil inside the compression
mechanisms 21a to 21c can be reduced and the prediction error of
the refrigerant quantity can be reduced during refrigerant quantity
judgment operation. Since the stagnation of refrigerant in the
refrigeration machine oil can accordingly be prevented in the
compression mechanisms 21a to 21c during the refrigerant quantity
judgment operation, a more precise refrigerant quantity judging
operation is made possible.
(2)
[0100] In the air conditioner 1, the judgment of the refrigerant
stagnation judgment means is performed based on the temperature
inside the compression mechanisms 21a to 21c. For this reason, the
temperature inside the compressors 22a to 22c, 27a to 27c, and 28a
to 28c can be measured and it is possible to judge whether
refrigerant has stagnated in the refrigeration machine oil inside
the compression mechanisms 21a to 21c.
(3)
[0101] In the air conditioner 1, the compressors 22a to 22c, 27a to
27c, and 28a to 28c are warmed up for a first prescribed length of
time in the refrigerant de-stagnation operation. Therefore, the
refrigerant de-stagnation operation entails operating the
compressors 22a to 22c, 27a to 27c, and 28a to 28c for a first
prescribed length of time, whereby the compression mechanisms 21a
to 21c can be warmed (warm-up operation). The interior of the
compression mechanisms 21a to 21c can accordingly be sufficiently
warmed up and the stagnation of refrigerant in the refrigeration
machine oil inside the compression mechanisms 21a to 21c can be
eliminated.
(4)
[0102] A plurality of heat source units 2a to 2c is present in the
air conditioner 1. Therefore, the service life of the entire system
can be extended without placing a load exclusively on a single unit
even during low-load operation because the heat source units 2a to
2c in the system can be placed in a rotation and driven at fixed
intervals of time one unit at a time.
(5)
[0103] In the air conditioner 1, the compression mechanisms 21a to
21c have a plurality of compressors 22a to 22c, 27a to 27c, and 28a
to 28c. Therefore, the capacity of the compression mechanisms 21a
to 21c can be varied by controlling the number of compressors 22a
to 22c, 27a to 27c, and 28a to 28c. Therefore, all of the heat
source units 2a to 2c can be continuously operated and the pooling
of refrigerant and oil in the refrigerant circuit 7 can be
prevented to the extent possible even when the operating load of
the utilization units 3a, 3b, . . . has been reduced. Also, the
remaining compressors can handle the load even if one of the
compressors 22a to 22c, 27a to 27c, and 28a to 28c malfunctions.
For this reason, a complete stoppage of the air conditioner can be
avoided.
(6)
[0104] In the air conditioner 1, all of the compressors 22a to 22c,
27a to 27c, and 28a to 28c can be operated in a rotation of one
unit at a time for a second prescribed length of time when a
plurality of compressors 22a to 22c, 27a to 27c, and 28a to 28c is
present. Since the cooling operation can be performed when the
temperature of the outside is low during the refrigerant
de-stagnation operation, it is difficult to operate the all of the
compressors 22a to 22c, 27a to 27c, and 28a to 28c at the same time
because of the low level of the load. For this reason, units are
operated one unit at a time for a second prescribed length of time,
whereby all of the compressors 22a to 22c, 27a to 27c, and 28a to
28c can be driven in advance.
(7)
[0105] In the air conditioner 1, an oil-return operation is further
carried out after the refrigerant de-stagnation operation. In the
oil-return operation, a control is performed so that the flow rate
of refrigerant in the pipes can be set to be a prescribed flow rate
or higher. Therefore, oil that is pooled in the refrigerant circuit
7 can be returned by further carrying out an oil-return operation.
The oil pooled in the refrigerant circuit 7 can be reliably
returned to the compressors 22a to 22c, 27a to 27c, and 28a to 28c.
The refrigerant quantity judgment operation can accordingly be
carried out with greater precision.
Other Embodiments
[0106] An embodiment of the present invention was described above
with reference to the drawings; however, the specific configuration
is not limited to the embodiment, and modifications can be made in
a range that does not depart from the main point of the
invention.
(A)
[0107] In the embodiment described above, air-cooled heat source
units 2a to 2c for which outside air is used as a heat source are
used as the heat source units 2a to 2c of the air conditioner 1,
but a water-cooled or an ice-storage heat source unit may also be
used.
(B)
[0108] In the embodiment described above, the air conditioner 1 is
capable of switching between cooling and heating operation, but it
is also possible to use a cooling-dedicate air conditioner or an
air conditioner that is capable of simultaneous cooling and heating
operation.
(C)
[0109] In the embodiment described above, three heat source units
2a to 2c having the same air conditioning capacity were connected
in parallel, but heat source units having different air
conditioning capacity may also be used, and two or more heat source
units without restriction to three units may also be connected in
parallel.
(D)
[0110] In the embodiment described above, operation controllers 6a
to 6c are housed in the heat source units 2a to 2c, but it is
possible to have a single operation controller as the entire air
conditioner.
(E)
[0111] In the embodiment described above, the refrigerant
stagnation judgment means judged whether the refrigerant has
stagnated in the compressors 22a to 22c, 27a to 27c, and 28a to 28c
on the basis of the temperature of the outside air, but the
judgment can be performed based on the temperature inside the
compression mechanisms 21a to 21c, may be performed by acquiring
weather information from an external server 10 that provides
weather information via the Internet or another communication line
9 and making a judgment based on the weather information (FIG. 7),
or may be performed based on a refrigerant stagnation time interval
in which the refrigerant is predicted to readily stagnate in the
compressors 22a to 22c, 27a to 27c, and 28a to 28c.
(F)
[0112] In the embodiment described above, a plurality of heat
source units 2a to 2c was used, but no limitation is imposed by a
plurality of units, and a single unit may be used.
(G)
[0113] In the embodiment described above, three compressors 22a to
22c, 27a to 27c, and 28a to 28c were driven for 15 minutes each
during the refrigerant de-stagnation operation, but the length of
time may be 5, 10, 20, or 30, without being limited to 15 minutes.
All of the compressors 22a to 22c, 27a to 27c, and 28a to 28c are
not required to be driven, and at least a compressor that has not
been driven may be driven and operated during the refrigerant
quantity judging operation.
(H)
[0114] In the embodiment described above, the refrigerant
de-stagnation operation was carried out by using a warm-up
operation in which the compressors 22a to 22c, 27a to 27c, and 28a
to 28c are driven to warm up the compression mechanisms 21a to 21c,
but no limitation is imposed thereby, and the compression
mechanisms 21a to 21c may be warmed up using a heater.
(I)
[0115] In the embodiment described above, an oil-return operation
is carried out immediately after the refrigerant de-stagnation
operation, but an oil-return operation does not necessarily have to
be performed.
INDUSTRIAL APPLICABILITY
[0116] The air conditioner of the present invention can eliminate
the stagnation of refrigerant in refrigeration machine oil inside a
compression mechanism prior to a refrigerant quantity judging
operation. Since a highly precise refrigerant quantity judging
operation can be performed, the present invention is useful as a
refrigerant circuit of an air conditioner, an air conditioner
provided therewith, and other air conditioners.
* * * * *