U.S. patent application number 14/390852 was filed with the patent office on 2015-02-26 for air conditioner.
The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Yukako Kanazawa, Tatsuya Makino, Junichi Shimoda.
Application Number | 20150052923 14/390852 |
Document ID | / |
Family ID | 49327548 |
Filed Date | 2015-02-26 |
United States Patent
Application |
20150052923 |
Kind Code |
A1 |
Kanazawa; Yukako ; et
al. |
February 26, 2015 |
AIR CONDITIONER
Abstract
An air conditioner includes an outdoor fan and a refrigerant
circuit having a compressor, an outdoor heat exchanger, an
expansion valve, and an indoor heat exchanger connected to each
other. An expansion valve refrigerant discharge control, in which
the compressor is driven in a state where the outdoor fan is
stopped and the expansion valve is open, is performed when a
cooling start noise reduction condition that a state of refrigerant
at inlet and outlet ports of the expansion valve is in a one-phase
liquid state is satisfied when starting the cooling operation. An
expansion valve normal switching control, in which an opening of
the expansion valve is reduced and an operating frequency of the
compressor is increased, is performed after the expansion valve
refrigerant discharge control.
Inventors: |
Kanazawa; Yukako;
(Sakai-shi, JP) ; Shimoda; Junichi; (Sakai-shi,
JP) ; Makino; Tatsuya; (Sakai-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Family ID: |
49327548 |
Appl. No.: |
14/390852 |
Filed: |
April 1, 2013 |
PCT Filed: |
April 1, 2013 |
PCT NO: |
PCT/JP2013/059857 |
371 Date: |
October 6, 2014 |
Current U.S.
Class: |
62/223 ; 62/507;
62/528 |
Current CPC
Class: |
F24F 1/40 20130101; F25B
2313/0314 20130101; F25B 49/022 20130101; F25B 41/062 20130101;
F25B 2313/006 20130101; F25B 2313/02741 20130101; F25B 2313/005
20130101; F25B 2600/2513 20130101; F25B 13/00 20130101; F25B
2313/0315 20130101; F25B 2313/0294 20130101 |
Class at
Publication: |
62/223 ; 62/507;
62/528 |
International
Class: |
F24F 1/40 20060101
F24F001/40; F25B 41/06 20060101 F25B041/06; F25B 49/02 20060101
F25B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2012 |
JP |
2012-088669 |
Claims
1. An air conditioner comprising: a refrigerant circuit including a
compressor, an outdoor heat exchanger, an expansion valve, and an
indoor heat exchanger connected with each other; and an outdoor fan
arranged and configured to supply outdoor air to the outdoor heat
exchanger, the outdoor air being a source of cooling of refrigerant
which flows through the outdoor heat exchanger, a cooling operation
being performed by driving the outdoor fan and circulating
refrigerant through the compressor, the outdoor heat exchanger, the
expansion valve, and the indoor heat exchanger in order, an
expansion valve refrigerant discharge control, in which the
compressor is driven in a state where the outdoor fan is stopped
and the expansion valve is open, being performed when a cooling
start noise reduction condition that a state of refrigerant at
inlet and outlet ports of the expansion valve is in a one-phase
liquid state is satisfied when starting the cooling operation, and
an expansion valve normal switching control, in which an opening of
the expansion valve is reduced and an operating frequency of the
compressor is increased, being performed after the expansion valve
refrigerant discharge control.
2. The air conditioner (1) according to claim 1, wherein it is
determined that the cooling start noise reduction condition is
satisfied when an expansion valve reference temperature or an
equivalent temperature is lower than a noise countermeasure
determining temperature, the noise countermeasure determining
temperature is a threshold obtained from a temperature of the
indoor heat exchanger or an equivalent temperature, and the
expansion valve reference temperature is a temperature of
refrigerant at the inlet and outlet ports of the expansion
valve.
3. The air conditioner according to claim 1, wherein the operating
frequency of the compressor in the expansion valve refrigerant
discharge control is set to a noise reduction activation frequency,
the noise reduction activation frequency is lower than an
activation frequency, and the activation frequency is an operating
frequency of the compressor when starting the cooling operation in
a case where the cooling start noise reduction condition is not
satisfied.
4. The air conditioner according to claim 1, wherein the opening of
the expansion valve in the expansion valve refrigerant discharge
control is set to a noise reduction activation opening, the a noise
reduction activation opening is larger than an activation opening,
and the activation opening is the opening of the expansion valve
when starting the cooling operation in a case where the cooling
start noise reduction condition is not satisfied.
5. The air conditioner according to claim 1, wherein the opening of
the expansion valve is reduced before the operating frequency of
the compressor is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control.
6. The air conditioner according to claim 1, wherein the opening of
the expansion valve is reduced in a state where the operating
frequency of the compressor is temporarily reduced when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
7. The air conditioner according to claim 1, wherein the expansion
valve is provided in the refrigerant circuit in a state where
refrigerant flows in with a horizontal orientation and refrigerant
flows out in a downward direction during the cooling operation.
8. The air conditioner according to claim 2, wherein the operating
frequency of the compressor in the expansion valve refrigerant
discharge control is set to a noise reduction activation frequency,
the noise reduction activation frequency is lower than an
activation frequency, and the activation frequency is an operating
frequency of the compressor when starting the cooling operation in
a case where the cooling start noise reduction condition is not
satisfied.
9. The air conditioner according to claim 2, wherein the opening of
the expansion valve in the expansion valve refrigerant discharge
control is set to a noise reduction activation opening, the a noise
reduction activation opening is larger than an activation opening,
and the activation opening is the opening of the expansion valve
when starting the cooling operation in a case where the cooling
start noise reduction condition is not satisfied.
10. The air conditioner according to claim 2, wherein the opening
of the expansion valve is reduced before the operating frequency of
the compressor is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control.
11. The air conditioner according to claim 2, wherein the opening
of the expansion valve is reduced in a state where the operating
frequency of the compressor is temporarily reduced when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
12. The air conditioner according to claim 3, wherein the opening
of the expansion valve in the expansion valve refrigerant discharge
control is set to a noise reduction activation opening, the a noise
reduction activation opening is larger than an activation opening,
and the activation opening is the opening of the expansion valve
when starting the cooling operation in a case where the cooling
start noise reduction condition is not satisfied.
13. The air conditioner according to claim 3, wherein the opening
of the expansion valve is reduced before the operating frequency of
the compressor is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control.
14. The air conditioner according to claim 3, wherein the opening
of the expansion valve is reduced in a state where the operating
frequency of the compressor is temporarily reduced when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
15. The air conditioner according to claim 4, wherein the opening
of the expansion valve is reduced before the operating frequency of
the compressor is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control.
16. The air conditioner according to claim 4, wherein the opening
of the expansion valve is reduced in a state where the operating
frequency of the compressor is temporarily reduced when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
17. The air conditioner according to claim 5, wherein the opening
of the expansion valve is reduced in a state where the operating
frequency of the compressor is temporarily reduced when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air conditioner, and in
particular, to an air conditioner which performs a cooling
operation by driving an outdoor fan and circulating refrigerant in
order of a compressor, an outdoor heat exchanger, an expansion
valve, and an indoor heat exchanger.
BACKGROUND ART
[0002] There is an air conditioner which performs a cooling
operation in the background art such as shown in PTL 1 (Japanese
Unexamined Patent Application Publication No. 9-133434). In detail,
the air conditioner has a refrigerant circuit which is configured
by connecting a compressor, an outdoor heat exchanger, an expansion
valve, and an indoor heat exchanger and an outdoor fan which
supplies outdoor air to the outdoor heat exchanger as a source for
cooling of refrigerant which flows through the outdoor heat
exchanger. Then, a cooling operation is performed in the air
conditioner by driving the outdoor fan and circulating refrigerant
in order of the compressor, the outdoor heat exchanger, the
expansion valve, and the indoor heat exchanger.
SUMMARY OF THE INVENTION
[0003] There is a problem in the air conditioner in the background
art in terms of cavitation noise in the expansion valve during the
cooling operation, and the inner diameter size of refrigerant pipes
at inlet and outlet ports of the expansion valve is devised with
regard to the problem of cavitation noise in the expansion
valve.
[0004] However, the cavitation noise in the expansion valve most
remarkably appears when starting the cooling operation under low
temperature conditions such as when the outdoor temperature is low.
Then, it is not possible for the inner diameter size of the
refrigerant pipes at inlet and outlet ports of the expansion valve
in the air conditioner in the background art to be devised to
sufficiently suppress the cavitation noise in the expansion valve
when starting the cooling operation under the low temperature
conditions.
[0005] The object of the invention is, in an air conditioner which
performs a cooling operation by driving an outdoor fan and
circulating refrigerant in order of a compressor, an outdoor heat
exchanger, an expansion valve, and an indoor heat exchanger, to
sufficiently suppress cavitation noise in the expansion valve when
starting the cooling operation under low temperature
conditions.
[0006] An air conditioner according to a first aspect of the
present invention is an air conditioner which has a refrigerant
circuit which is configured by connecting a compressor, an outdoor
heat exchanger, an expansion valve, and an indoor heat exchanger
and an outdoor fan which supplies outdoor air to the outdoor heat
exchanger as a source for cooling of refrigerant which flows
through the outdoor heat exchanger. A control section of the air
conditioner performs a cooling operation by driving the outdoor fan
and circulating refrigerant in order of the compressor, the outdoor
heat exchanger, the expansion valve, and the indoor heat exchanger.
The air conditioner performs an expansion valve refrigerant
discharge control when a cooling start noise reduction condition
that a state of refrigerant at inlet and outlet ports of the
expansion valve is in a one-phase liquid state is satisfied when
starting the cooling operation and performs an expansion valve
normal switching control after the expansion valve refrigerant
discharge control. The expansion valve coolant discharge control is
a control where the compressor is driven in a state where the
outdoor fan is stopped and the expansion valve is open. The
expansion valve normal switching control is a control where an
opening of the expansion valve is reduced and an operating
frequency of the compressor is increased.
[0007] The inventors of the present application focus on the
relationship between cavitation noise in the expansion valve and
the state of refrigerant at the inlet and outlet ports of the
expansion valve. Then, it was found that refrigerant at the inlet
and outlet ports of the expansion valve is in the one-phase liquid
state when starting the cooling operation under low temperature
conditions, and due to the effect of this, cavitation noise in the
expansion valve is remarkable. That is, it was found that the state
of refrigerant at the inlet and outlet ports of the expansion valve
when starting the cooling operation affects cavitation noise in the
expansion valve. That is, cavitation noise in the expansion valve
remarkably appears when starting the cooling operation when there
is no change in the state where liquid refrigerant has accumulated
at the inlet and outlet ports of the expansion valve. However,
cavitation noise in the expansion valve is suppressed when starting
the cooling operation in a state where liquid refrigerant has not
accumulated at the inlet and outlet ports of the expansion
valve.
[0008] Therefore, in the air conditioner according to the first
aspect of the present invention, by considering the state of
refrigerant at the inlet and outlet ports of the expansion valve,
it is determined whether or not the cooling start noise reduction
condition, which shows that the state of refrigerant at the inlet
and outlet ports of the expansion valve is in the one-phase liquid
state, is satisfied when starting the cooling operation. Then, in
the case where the cooling start noise reduction condition is
satisfied, the expansion valve refrigerant discharge control is
performed so that the compressor is driven in the state where the
outdoor fan is stopped and the expansion valve is open. Then, after
the expansion valve refrigerant discharge control, the expansion
valve normal switching control is performed so that the opening of
the expansion valve is reduced and the operating frequency of the
compressor is increased.
[0009] Due to this, in the air conditioner according to the first
aspect of the present invention, it is determined whether or not
the cooling operation is starting under the low temperature
conditions due to the state of refrigerant at the inlet and outlet
ports of the expansion valve which is a direct indicator of whether
or not there are conditions where cavitation noise in the expansion
valve will remarkably appear. Then, due to the expansion valve
refrigerant discharge control being performed in the case where the
cooling start noise reduction condition is satisfied, the state is
created where liquid refrigerant has not accumulated at the inlet
and outlet ports of the expansion valve by discharging liquid
refrigerant at the expansion valve and the inlet and outlet ports
thereof to the indoor heat exchanger side. That is, liquid
refrigerant smoothly flows to the indoor heat exchanger side while
as little liquid refrigerant as possible is supplied to the
expansion valve by suppressing refrigerant condensing performance
in the outdoor heat exchanger due to the outdoor fan being stopped
and the expansion valve being open when driving the compressor.
Then, cavitation noise in the expansion valve is suppressed by
switching the expansion valve to normal control due to the
expansion valve normal switching control being performed in a state
where the state is created where liquid refrigerant has not
accumulated at the inlet and outlet ports of the expansion valve
due to the expansion valve refrigerant discharge control.
[0010] In this manner, in the air conditioner according to the
first aspect of the present invention, it is possible to
sufficiently suppress cavitation noise in the expansion valve when
starting the cooling operation under the low temperature conditions
due to the expansion valve refrigerant discharge control and the
expansion valve normal switching control being performed in the
case where the cooling start noise reduction condition is
satisfied.
[0011] An air conditioner according to a second aspect of the
present invention is the air conditioner according to the first
aspect of the present invention where it is determined that the
cooling start noise reduction condition is satisfied in a case
where an expansion valve reference temperature which is a
temperature of refrigerant at the inlet and outlet ports of the
expansion valve or an equivalent temperature is lower than a noise
countermeasure determining temperature which is a threshold which
is obtained from a temperature of the indoor heat exchanger or an
equivalent temperature.
[0012] It is possible for refrigerant at the inlet and outlet ports
of the expansion valve to be equal to or lower than a refrigerant
saturation temperature in a case where the expansion valve
reference temperature which is the temperature of refrigerant at
the inlet and outlet ports of the expansion valve or the equivalent
temperature is reduced to a temperature which is close to a
temperature on the indoor side when starting the cooling
operation.
[0013] Therefore, in the air conditioner according to the second
aspect of the present invention, it is determined that the cooling
start noise reduction condition is satisfied in the case where the
expansion valve reference temperature which is the temperature of
refrigerant at the inlet and outlet ports of the expansion valve is
lower than the noise countermeasure determining temperature which
is a threshold which is obtained from the temperature of the indoor
heat exchanger. Here, by providing a temperature sensor at the
inlet and outlet ports of the expansion valve, it is possible to
use a temperature value which is detected by the temperature sensor
as the expansion valve reference temperature. In addition, in a
case of providing a temperature sensor which detects a temperature
of the outdoor heat exchanger and an outdoor temperature, a
temperature value which is detected by the temperature sensor may
be used as a temperature which is equivalent to the temperature of
refrigerant at the inlet and outlet ports of the expansion valve.
In addition, in a case of providing a temperature sensor which
detects the temperature of the indoor heat exchanger, it is
possible to use a threshold which is obtained from a temperature
value which is detected by the temperature sensor. In addition, in
a case of providing the temperature sensor which detects an indoor
temperature, a temperature value which is detected by the
temperature sensor may be used as a temperature which is equivalent
to the temperature of the indoor heat exchanger.
[0014] Due to this, in the air conditioner according to the second
aspect of the present invention, it is possible to correctly
determine whether or not the cooling start noise reduction
condition is satisfied using the expansion valve reference
temperature and the noise countermeasure determining
temperature.
[0015] An air conditioner according to a third aspect of the
present invention is the air conditioner according to the first or
second aspect of the present invention where the operating
frequency of the compressor in the expansion valve refrigerant
discharge control is set to a noise reduction activation frequency
which is lower than an activation frequency which is an operating
frequency of the compressor when starting the cooling operation in
a case where the cooling start noise reduction condition is not
satisfied.
[0016] Liquid refrigerant flows smoothly through the expansion
valve to the indoor heat exchanger side by opening the expansion
valve in the expansion valve refrigerant discharge control.
However, there is a concern that liquid refrigerant will return
from the indoor heat exchanger side to the compressor if the
operating frequency of the compressor is high.
[0017] Therefore, in the air conditioner according to the third
aspect of the present invention, the operating frequency of the
compressor in the expansion valve refrigerant discharge control is
set to the noise reduction activation frequency which is lower than
the activation frequency when starting the cooling operation in the
case where the cooling start noise reduction condition is not
satisfied.
[0018] Due to this, in the air conditioner according to the third
aspect of the present invention, it is possible to suppress the
concern that liquid refrigerant will return from the indoor heat
exchanger side to the compressor while obtaining a smooth flow of
liquid refrigerant to the indoor heat exchanger side in the
expansion valve refrigerant discharge control.
[0019] An air conditioner according to a fourth aspect of the
present invention is the air conditioner according to the first to
third aspects of the present invention where the opening of the
expansion valve in the expansion valve coolant discharge control is
set to a noise reduction activation opening which is larger than an
activation opening which is the opening of the expansion valve when
starting the cooling operation in a case where the cooling start
noise reduction condition is not satisfied.
[0020] Liquid refrigerant flows smoothly through the expansion
valve to the indoor heat exchanger side by opening the expansion
valve in the expansion valve refrigerant discharge control.
However, at this time, there is a concern that flow path resistance
when refrigerant passes through the expansion valve will be large
if the opening of the expansion valve is small and smooth flow of
liquid refrigerant to the indoor heat exchanger side will be
impeded.
[0021] Therefore, in the air conditioner according to the fourth
aspect of the present invention, the opening of the expansion valve
in the expansion valve refrigerant discharge control is set to the
noise reduction activation opening which is larger than the
activation opening when starting the cooling operation in the case
where the cooling start noise reduction condition is not
satisfied.
[0022] Due to this, in the air conditioner according to the fourth
aspect of the present invention, it is possible to reliably obtain
a smooth flow of liquid refrigerant to the indoor heat exchanger
side in the expansion valve refrigerant discharge control by the
flow path resistance when liquid refrigerant passes through the
expansion valve being as small as possible.
[0023] An air conditioner according to a fifth aspect of the
present invention is the air conditioner according to the first to
fourth aspects of the present invention where the opening of the
expansion valve is reduced by the control section before the
operating frequency of the compressor is increased when switching
from the expansion valve refrigerant discharge control to the
expansion valve normal switching control.
[0024] A case is assumed where an action of reducing the opening of
the expansion valve is performed after the operating frequency of
the compressor is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control. In this case, due to the state, which is only
temporary, where the operating frequency of the compressor is high
in a state where the opening of the expansion valve is large, there
is a concern that liquid refrigerant will return from the indoor
heat exchanger side to the compressor.
[0025] Therefore, in the air conditioner according to the fifth
aspect of the present invention, the opening of the expansion valve
is reduced before the operating frequency of the compressor is
increased when switching from the expansion valve refrigerant
discharge control to the expansion valve normal switching
control.
[0026] Due to this, in the air conditioner according to the fifth
aspect of the present invention, it is possible to suppress the
concern that liquid refrigerant will return from the indoor heat
exchanger side to the compressor after the expansion valve coolant
discharge control.
[0027] An air conditioner according to a sixth aspect of the
present invention is the air conditioner according to the first to
fifth aspects of the present invention where the opening of the
expansion valve is reduced by the control section in a state where
the operating frequency of the compressor is temporarily reduced
when switching from the expansion valve refrigerant discharge
control to the expansion valve normal switching control.
[0028] A case is assumed where an action of reducing the opening of
the expansion valve is performed while the operating frequency of
the compressor is maintained as it is when switching from the
expansion valve refrigerant discharge control to the expansion
valve normal switching control. In this case, there is a tendency
for a pressure of refrigerant to be raised at a portion of the
refrigerant circuit on an upstream side of the expansion valve. If
this is the case, there are several concerns with a state where the
inlet and outlet ports in the expansion valve are filled again with
liquid refrigerant even if a state is created where the flow rate
of liquid refrigerant which flows into the expansion valve
increases and liquid refrigerant has not accumulated at the inlet
and outlet ports of the expansion valve due to the expansion valve
refrigerant discharge control.
[0029] Therefore, in the air conditioner according to the sixth
aspect of the present invention, the opening of the expansion valve
is reduced in a state where the operating frequency of the
compressor is temporarily reduced when switching from the expansion
valve refrigerant discharge control to the expansion valve normal
switching control.
[0030] Due to this, in the air conditioner according to the sixth
aspect of the present invention, it is possible to suppress the
state where the inlet and outlet ports in the expansion valve are
filled again with liquid refrigerant after the expansion valve
refrigerant discharge control by suppressing the tendency for the
pressure of refrigerant to be raised at the portion of the
refrigerant circuit on the upstream side of the expansion
valve.
[0031] An air conditioner according to a seventh aspect of the
present invention is the air conditioner according to the first to
sixth aspects of the present invention where the expansion valve is
provided in the refrigerant circuit in a state with an arrangement
where refrigerant flows in with a horizontal orientation and
refrigerant flows out in a downward direction during the cooling
operation.
[0032] There is a tendency for it to be easy for cavitation noise
in the expansion valve to be generated in a configuration where the
expansion valve is provided in the refrigerant circuit in the state
with an arrangement where refrigerant flows in with the horizontal
orientation and refrigerant flows out in a downward direction
during the cooling operation (referred to below as "positive cycle
arrangement state").
[0033] However, in the air conditioner according to the seventh
aspect of the present invention, it is possible to sufficiently
suppress cavitation noise in the expansion valve even if the
expansion valve is arranged in the positive cycle arrangement state
due to the expansion valve refrigerant discharge control and the
expansion valve normal switching control being performed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a schematic configuration diagram of an air
conditioner according to an embodiment of the present
invention.
[0035] FIG. 2 is a schematic cross sectional diagram of an
expansion valve.
[0036] FIG. 3 is a control block diagram of the air
conditioner.
[0037] FIG. 4 is a flow chart of a cooling activation control.
[0038] FIG. 5 is a time chart for a compressor, an outdoor fan, and
the expansion valve during the cooling activation control (in a
case where a cooling start noise reduction condition is
satisfied).
DESCRIPTION OF EMBODIMENTS
[0039] An embodiment of an air conditioner according to the present
invention will be described below based on the drawings. Here, the
detailed configuration of the air conditioner according to the
present invention is not limited to the embodiment described below
and modifications are possible within a scope which does not depart
from the gist of the invention.
[0040] (1) Air Conditioner Configuration
[0041] FIG. 1 is a schematic configuration diagram of an air
conditioner 1 according to an embodiment of the present
invention.
[0042] The air conditioner 1 is an apparatus which is able to
perform cooling and heating indoors such as in a building by
performing a vapor compression refrigerating cycle. The air
conditioner 1 is mainly configured by connecting an outdoor unit 2
and an indoor unit 4. Here, the outdoor unit 2 and the indoor unit
4 are connected via a liquid refrigerant linking pipe 5 and a gas
refrigerant linking pipe 6. That is, a vapor compression
refrigerant circuit 10 in the air conditioner 1 is configured by
the outdoor unit 2 and the indoor unit 4 being connected via the
refrigerant linking pipes 5 and 6.
[0043] <Indoor Unit>
[0044] The indoor unit 4 is arranged indoors and configures a
portion of the refrigerant circuit 10. The indoor unit 4 mainly has
an indoor heat exchanger 41.
[0045] The indoor heat exchanger 41 is a heat exchanger which cools
indoor air with a function as an evaporator for refrigerant during
a cooling operation and which heats indoor air with a function as a
radiator for refrigerant during a heating operation. The liquid
side of the indoor heat exchanger 41 is connected with the liquid
refrigerant linking pipe 5 and the gas side of the indoor heat
exchanger 41 is connected with the gas refrigerant linking pipe
6.
[0046] The indoor unit 4 has an indoor fan 42 for sucking indoor
air into the indoor unit 4 and supplying the indoor air to indoors
as supply air after indoor air has exchanged heat with refrigerant
in the indoor heat exchanger 41. That is, the indoor unit 4 has an
indoor fan 42 as a fan which supplies indoor air to the indoor heat
exchanger 41 as a source for heating or a source for cooling of
refrigerant which flows in the indoor heat exchanger 41. Here, a
centrifugal fan, a multi-blade fan, or the like, which is driven by
an indoor fan motor 43, is used as the indoor fan 42.
[0047] Various types of sensors are provided in the indoor unit 4.
In detail, an indoor heat exchanger temperature sensor 44, which
detects a temperature Trr of refrigerant in the indoor heat
exchanger 41, is provided in the indoor heat exchanger 41. An
indoor air temperature sensor 45, which detects a temperature Tra
of indoor air which is sucked into the indoor unit 4, is provided
in the indoor unit 4.
[0048] The indoor unit 4 has an indoor side control section 46
which controls the actions of each section which configures the
indoor unit 4. Then, the indoor side control section 46 has a
microcomputer, a memory, and the like which are provided in order
to perform controlling of the indoor unit 4 and it is possible to
perform exchanging of control signals and the like between the
indoor side control section 46 and a remote control (which is not
shown in the diagram) and perform exchanging of control signals and
the like between the indoor side control section 46 and the outdoor
unit 2 via a transmission wire 7.
[0049] <Outdoor Unit>
[0050] The outdoor unit 2 is arranged outdoors and configures a
portion of the refrigerant circuit 10. The outdoor unit 2 mainly
has a compressor 21, a four way valve 22, an outdoor heat exchanger
23, an expansion valve 24, an accumulator 25, a liquid side
shut-off valve 26, and a gas side shut-off valve 27.
[0051] The compressor 21 is a device which compresses until
low-pressure refrigerant in the refrigerating cycle reaches a high
pressure. The compressor 21 has a sealed structure where a positive
displacement compressor element such as a rotary type or a scroll
type (which is not shown in the diagram) is rotationally driven by
a compressor motor 21a which is controlled by an inverter. The
suction side of the compressor 21 is connected with a suction pipe
31 and the discharge side of the compressor 21 is connected with a
discharge pipe 32. The suction pipe 31 is a coolant pipe which
connects the suction side of the compressor 21 and a first port 22a
of the four way valve 22. The discharge pipe 32 is a coolant pipe
which connects the discharge side of the compressor 21 and a second
port 22b of the four way valve 22.
[0052] The four way valve 22 is a switching valve for switching the
direction of the flow of refrigerant in the refrigerant circuit 10.
The four way valve 22 performs switching of the cooling cycle state
during the cooling operation so that the outdoor heat exchanger 23
functions as a radiator for refrigerant which is compressed in the
compressor 21 and the indoor heat exchanger 41 functions as an
evaporator for refrigerant which releases heat in the outdoor heat
exchanger 23. That is, the four way valve 22 performs switching
during the cooling operation so that the second port 22b and a
third port 22c communicate and the first port 22a and a fourth port
22d communicate. Due to this, the discharge side of the compressor
21 (here, the discharge pipe 32) and the gas side of the outdoor
heat exchanger 23 (here, a first gas coolant pipe 33) are connected
(refer to the solid line in the four way valve 22 in FIG. 1).
Moreover, the suction side of the compressor 21 (here, the suction
pipe 31) and the gas refrigerant linking pipe 6 side (here, a
second gas refrigerant pipe 34) are connected (refer to the solid
line in the four way valve 22 in FIG. 1). In addition, the four way
valve 22 performs switching of the heating cycle state during the
heating operation so that the outdoor heat exchanger 23 functions
as an evaporator for refrigerant which releases heat in the outdoor
heat exchanger 23 and the indoor heat exchanger 41 functions as a
radiator for refrigerant which is compressed in the compressor 21.
That is, the four way valve 22 performs switching during the
heating operation so that the second port 22b and the fourth port
22d communicate and the first port 22a and the third port 22c
communicate. Due to this, the discharge side of the compressor 21
(here, the discharge pipe 32) and the gas refrigerant linking pipe
6 side (here, the second gas refrigerant pipe 34) are connected
(refer to the dashed line in the four way valve 22 in FIG. 1).
Moreover, the suction side of the compressor 21 (here, the suction
pipe 31) and the gas side of the outdoor heat exchanger 23 (here,
the first gas refrigerant pipe 33) are connected (refer to the
dashed line in the four way valve 22 in FIG. 1). The first gas
coolant pipe 33 is a refrigerant pipe for connecting the third port
22c of the four way valve 22 and the gas side of the outdoor heat
exchanger 23. The second gas refrigerant pipe 34 is a coolant pipe
for connecting the fourth port 22d of the four way valve 22 and the
gas refrigerant linking pipe 6 side.
[0053] The outdoor heat exchanger 23 is a heat exchanger that
functions as a radiator for refrigerant with the outdoor air as a
source for cooling during the cooling operation and functions as an
evaporator for refrigerant with the outdoor air as a source for
heating during the heating operation. The liquid side of the
outdoor heat exchanger 23 is connected with a liquid refrigerant
pipe 35 and the gas side of the outdoor heat exchanger 23 is
connected with the first gas refrigerant pipe 33. The liquid
refrigerant pipe 35 is a refrigerant pipe which connects the liquid
side of the outdoor heat exchanger 23 and the liquid refrigerant
linking pipe 5 side.
[0054] The expansion valve 24 is a valve which depressurizes
high-pressure refrigerant to low-pressure in the refrigerating
cycle where heat is released in the outdoor heat exchanger 23
during the cooling operation. In addition, the expansion valve 24
is a valve which depressurizes high-pressure refrigerant to
low-pressure in the refrigerating cycle where heat is released in
the indoor heat exchanger 41 during the heating operation. The
expansion valve 24 is provided in a portion in the liquid
refrigerant pipe 35 which is closer to the liquid side shut-off
valve 26. Here, an electric expansion valve is used as the
expansion valve 24. In more detail, the expansion valve 24 mainly
has a valve main body 240, a valve body 250, and a driving
mechanism 260 as shown in FIG. 2. The valve main body 240 is a
member where a valve seat 242 which is an opening in a valve
chamber 241 is formed. A first refrigerant port 243 which is an
opening toward the side of the valve chamber 241 and a second
refrigerant port 244 which is an opening toward the bottom of the
valve chamber 241 are formed in the valve main body 240. Then, the
first refrigerant port 243 is connected with a portion of the
liquid refrigerant pipe 35 which is closer to the outdoor heat
exchanger 23 and the second refrigerant port 244 is connected with
a portion of the liquid refrigerant pipe 35 which is closer to the
liquid side shut-off valve 26. As a result, the expansion valve 24
is provided in the refrigerant circuit 10 in a state with an
arrangement where refrigerant flows in with a horizontal
orientation and refrigerant flows out in a downward direction
during the cooling operation (referred to below as "positive cycle
arrangement state"). An orifice hole 242a, which is an opening so
that the valve chamber 241 and the second refrigerant port 244
communicate in an up and down direction, is formed in the valve
seat 242. The valve body 250 is a member which advances and
retreats with regard to the valve seat 242 in the up and down
direction due to the driving mechanism 260. The driving mechanism
260 is formed from a motor, a solenoid, or the like. With this
configuration, the expansion valve 24 depressurizes high-pressure
refrigerant to low pressure in the refrigerating cycle which flows
through the liquid refrigerant pipe 35.
[0055] The accumulator 25 is a container for temporarily
accumulating low-pressure refrigerant which is sucked into the
compressor 21. The accumulator 25 is provided in the suction pipe
31.
[0056] The liquid side shut-off valve 26 and the gas side shut-off
valve 27 are valves which are provided with connection ports with
external equipment and piping (in detail, the liquid refrigerant
linking pipe 5 and the gas refrigerant linking pipe 6). The liquid
side shut-off valve 26 is provided at an end section of the liquid
refrigerant pipe 35. The gas side shut-off valve 27 is provided at
an end section of the second gas refrigerant pipe 34.
[0057] The outdoor unit 2 has an outdoor fan 36 for sucking outdoor
air into the outdoor unit 2 and discharging outdoor air to the
outside after outdoor air has exchanged heat with refrigerant in
the outdoor heat exchanger 23. That is, the outdoor unit 2 has the
outdoor fan 36 as a fan which supplies outdoor air to the outdoor
heat exchanger 23 as a source for heating or a source for cooling
of refrigerant which flows through the outdoor heat exchanger 23.
Here, a propeller fan or the like, which is driven by an outdoor
fan motor 37, is used as the outdoor fan 36.
[0058] Various types of sensors are provided in the outdoor unit 2.
In detail, an outdoor heat exchanger temperature sensor 38, which
detects a temperature Tor of refrigerant in the outdoor heat
exchanger 23, is provided in the outdoor heat exchanger 23. An
outdoor air temperature sensor 39, which detects a temperature Toa
of outdoor air which is sucked into the outdoor unit 2, is provided
in the outdoor unit 2. A suction temperature sensor 47, which
detects a temperature Ts of low-pressure refrigerant in the
refrigerating cycle which is sucked into the compressor 21, is
provided in the suction pipe 31 or the compressor 21. A discharge
temperature sensor 48, which detects a temperature Td of
high-pressure refrigerant in the refrigerating cycle which is
discharged from the compressor 21, is provided in the discharge
pipe 32 or the compressor 21. A discharge pressure sensor 49, which
detects a pressure Pd of high-pressure refrigerant in the
refrigerating cycle which is discharged from the compressor 21, is
provided in the discharge pipe 32 or the compressor 21.
[0059] The outdoor unit 2 has an outdoor side control section 40
which controls the actions of each section which configures the
outdoor unit 2. Then, the outdoor side control section 40 has a
microcomputer, a memory, and the like which are provided in order
to perform controlling of the outdoor unit 2 and it is possible to
perform exchanging of control signals and the like between the
outdoor side control section 46 and the outdoor unit 2 via the
transmission wire 7.
[0060] <Refrigerant Linking Pipe>
[0061] When installing the air conditioner 1 at an installation
location such as on a building, the refrigerant linking pipes 5 and
6 are refrigerant pipes where construction work is carried out
onsite and use refrigerant pipes with various lengths and pipe
diameters according to installation conditions such as the
installation location and combination of the outdoor unit and the
indoor unit.
[0062] As described above, the refrigerant circuit 10 of the air
conditioner 1 is configured by connecting the outdoor unit 2, the
indoor unit 4, and the refrigerant linking pipes 5 and 6. Due to
the four way valve 22 switching to the cooling cycle state, the air
conditioner 1 performs the cooling operation by driving the outdoor
fan 36 and circulating refrigerant in order of the compressor 21,
the outdoor heat exchanger 23, the expansion valve 24, and the
indoor heat exchanger 41. In addition, due to the four way valve 22
switching to the heating cycle state, the air conditioner 1
performs the heating operation by driving the outdoor fan 36 and
circulating refrigerant in order of the compressor 21, the indoor
heat exchanger 41, the expansion valve 24, and the outdoor heat
exchanger 23. Here, there is a configuration where it is possible
to operate by switching between the cooling operation and the
heating operation, but there may be a configuration without a four
way valve where only the cooling operation is possible.
[0063] <Control Section>
[0064] It is possible for the air conditioner 1 to perform
controlling of each of the devices in the outdoor unit 2 and the
indoor unit 4 using the control section 8 which is configured from
the indoor side control section 46 and the outdoor side control
section 40. That is, the control section 8, which performs
operational control of the entirety of the air conditioner 1 which
includes the cooling operation and the heating operation as
described above, using the transmission wire 7 which connects
between the indoor side control section 46 and the outdoor side
control section 40.
[0065] As shown in FIG. 3, the control section 8 connects so that
it is possible to receive detection signals from the various
sensors 38, 39, 44, 45, 47-49 and the like and connects so that it
is possible to control the various devices and the valves 21, 22,
24, 37, 43, and the like based on the detection signals.
[0066] (2) Basic Air Conditioner Actions
[0067] Next, the basic actions of the air conditioner 1 (the
actions excluding cooling activation control which will be
described later) will be described using FIG. 1. It is possible for
the air conditioner 1 to perform the cooling operation and the
heating operation as basic actions.
[0068] <Heating Operation>
[0069] The four way valve 22 switches to the heating cycle state (a
state which is indicated by a dashed line in FIG. 1) during the
heating operation.
[0070] In the refrigerant circuit 10, low-pressure gas refrigerant
in the refrigerating cycle is sucked into the compressor 21 and is
discharged after being compressed so as to reach high pressure in
the refrigerating cycle.
[0071] High-pressure gas refrigerant which is discharged from the
compressor 21 is sent to the indoor heat exchanger 41 via the four
way valve 22, the gas side shut-off valve 27, and the gas
refrigerant linking pipe 6.
[0072] High-pressure gas refrigerant which is sent to the indoor
heat exchanger 41 becomes high-pressure liquid refrigerant due to
heat being released by heat exchange being performed with indoor
air, which is supplied as a source for cooling using the indoor fan
42, in the indoor heat exchanger 41. Due to this, indoor heating is
performed by indoor air being heated, and after this, supplied
indoors.
[0073] High-pressure liquid refrigerant which releases heat using
the indoor heat exchanger 41 is sent to the expansion valve 24 via
the liquid refrigerant linking pipe 5 and the liquid side shut-off
valve 26.
[0074] High-pressure liquid refrigerant which is sent to the
expansion valve 24 becomes low-pressure refrigerant in a state
being in two phases of liquid and gas by depressurizing to low
pressure in the refrigerating cycle using the expansion valve 24.
Low-pressure refrigerant in a state being in two phases of liquid
and gas which is depressurized using the expansion valve 24 is sent
to the outdoor heat exchanger 23.
[0075] Low-pressure coolant in a state being in two phases of
liquid and gas which is sent to the outdoor heat exchanger 23
becomes low-pressure gas refrigerant due to evaporation by heat
exchange being performed with outdoor air, which is supplied as a
source for heating using the outdoor fan 36, in the outdoor heat
exchanger 23.
[0076] Low-pressure refrigerant which is subject to evaporation
using the outdoor heat exchanger 23 is again sucked into the
compressor 21 via the four way valve 22.
[0077] <Cooling Operation>
[0078] The four way valve 22 switches to the cooling cycle state (a
state which is indicated by a solid line in FIG. 1) during the
cooling operation.
[0079] In the refrigerant circuit 10, low-pressure gas refrigerant
in the refrigerating cycle is sucked into the compressor 21 and is
discharged after being compressed so as to reach high pressure in
the refrigerating cycle.
[0080] High-pressure gas refrigerant which is discharged from the
compressor 21 is sent to the outdoor heat exchanger 23 via the four
way valve 22.
[0081] High-pressure gas refrigerant which is sent to the outdoor
heat exchanger 23 becomes high-pressure liquid refrigerant due to
heat being released by heat exchange being performed with outdoor
air, which is supplied as a source for cooling using the outdoor
fan 36, in the outdoor heat exchanger 23.
[0082] High-pressure liquid refrigerant which releases heat using
the outdoor heat exchanger 23 is sent to the expansion valve
24.
[0083] High-pressure liquid refrigerant which is sent to the
expansion valve 24 becomes low-pressure refrigerant in a state
being in two phases of liquid and gas by depressurizing to low
pressure in the refrigerating cycle using the expansion valve 24.
Low-pressure refrigerant in a state being in two phases of liquid
and gas which is depressurized using the expansion valve 24 is sent
to the indoor heat exchanger 41 via the liquid side shut-off valve
26 and the liquid refrigerant linking pipe 5.
[0084] Low-pressure refrigerant in a state being in two phases of
liquid and gas which is sent to the indoor heat exchanger 41 is
subject to evaporation by heat exchange being performed with indoor
air, which is supplied as a source for heating using the indoor fan
42, in the indoor heat exchanger 41. Due to this, indoor cooling is
performed by indoor air being cooled, and after this, supplied
indoors.
[0085] Low-pressure refrigerant which is subject to evaporation
using the indoor heat exchanger 41 is again sucked into the
compressor 21 via the gas refrigerant linking pipe 6, the gas side
shut-off valve 27, and the four way valve 22.
[0086] (3) Cooling Activation Control
[0087] There is a problem in terms of cavitation noise in the
expansion valve 24 during the cooling operation. In particular,
cavitation noise in the expansion valve 24 most remarkably appears
when starting the cooling operation under low temperature
conditions such as when the outdoor temperature is low.
[0088] With regard to cavitation noise in the expansion valve 24
when starting the cooling operation under the low temperature
conditions in this manner, the inventors of the present application
focus on the relationship between cavitation noise in the expansion
valve 24 and the state of refrigerant at the inlet and outlet ports
of the expansion valve 24. Then, the state of refrigerant at the
inlet and outlet ports of the expansion valve 24 is in a one-phase
liquid state when starting the cooling operation under the low
temperature conditions, and due to the effect of this, it was found
that cavitation noise in the expansion valve 24 is remarkable. That
is, it was found that the state of refrigerant at the inlet and
outlet ports in the expansion valve 24 when starting the cooling
operation affects cavitation noise in the expansion valve 24. That
is, cavitation noise in the expansion valve 24 remarkably appears
when starting the cooling operation when there is no change in the
state where liquid refrigerant has accumulated at the inlet and
outlet ports of the expansion valve 24. However, cavitation noise
in the expansion valve 24 is suppressed when starting the cooling
operation in a state where liquid refrigerant has not accumulated
at the inlet and outlet ports of the expansion valve 24.
[0089] Therefore, in the air conditioner 1 according to the present
embodiment, it is determined whether or not a cooling start noise
reduction condition, which shows that the state of refrigerant at
the inlet and outlet ports of the expansion valve 24 is in the
one-phase liquid state, is satisfied in the cooling activation
control which is performed when starting the cooling operation as
follows. Then, cavitation noise in the expansion valve 24 is
sufficiently suppressed when starting the cooling operation under
low temperature conditions due to an expansion valve refrigerant
discharge control and an expansion valve normal switching control
being performed in the case where the cooling start noise reduction
condition is satisfied.
[0090] Next, the cooling activation control in the present
embodiment will be described using FIG. 1 to FIG. 5. Here, FIG. 4
is a flow chart of the cooling activation control. FIG. 5 is a time
chart for the compressor 21, the outdoor fan 36, and the expansion
valve 24 during the cooling activation control (in a case where the
cooling start noise reduction condition is satisfied). Here, the
cooling activation control which is described below is performed by
the control section 8 in the same manner as the basic actions
described above.
[0091] <Steps ST1 and ST4>
[0092] When there is a starting instruction for the cooling
operation through the remote control (which is not shown in the
diagram) or the like, first, the control section 8 performs a
determination process in step ST1. It is determined in step ST1
whether or not the cooling start noise reduction condition, which
shows that the state of refrigerant at the inlet and outlet ports
of the expansion valve 24 is in a one-phase liquid state, is
satisfied when starting the cooling operation. Due to this, it is
possible to determine whether or not the cooling operation is
starting under the low temperature conditions due to the state of
refrigerant at the inlet and outlet ports in the expansion valve 24
which is a direct indicator of whether or not there are conditions
such that cavitation noise in the expansion valve 24 will
remarkably appear.
[0093] Here, it is determined that the cooling start noise
reduction condition is satisfied in a case where an expansion valve
reference temperature Tev, which is the temperature of refrigerant
at the inlet and outlet ports of the expansion valve 24, is lower
than a noise countermeasure determining temperature Tevs which is a
threshold which is obtained from the temperature of the indoor heat
exchanger 41. This is because it is possible to see that
refrigerant at the inlet and outlet ports of the expansion valve 24
has a refrigerant saturation temperature or less in a case where
the expansion valve reference temperature Tev is less than a
temperature which is close to the temperature on the indoor side
when starting the cooling operation. Here, providing of a
temperature sensor at the inlet and outlet ports of the expansion
valve 24 and using a temperature value which is detected by the
temperature sensor as the expansion valve reference temperature Tev
has been considered. However, the temperature Tor in the outdoor
heat exchanger 23 which is a temperature which is equivalent to
this is used in order for temperature sensors to not be provided at
the inlet and outlet ports of the expansion valve 24. Here, the
outside air temperature Toa, which is a temperature which is
equivalent to the temperature Tor, may be used as the expansion
valve reference temperature Tev instead of the temperature Tor in
the outdoor heat exchanger 23. In addition, it is possible to use a
threshold which is obtained from the temperature Trr in the indoor
heat exchanger 41 as the noise countermeasure determining
temperature Tevs. Here, a threshold which is obtained from an
indoor temperature Tra, which is a temperature which is equivalent
to the temperature Trr, may be used as the noise countermeasure
determining temperature Tevs instead of the temperature Trr in the
indoor heat exchanger 41. Due to this, it is possible to correctly
determine whether or not the cooling start noise reduction
condition is satisfied using the expansion valve reference
temperature Tev and the noise countermeasure determining
temperature Tevs.
[0094] Then, in a case where the cooling start noise reduction
condition is not satisfied in step ST1, the process moves to the
process of step ST4 and a normal activation control is performed.
That is, in a case of starting the cooling operation not under the
low temperature conditions, the activation control when normally
starting the cooling operation is performed since the state of
refrigerant at the inlet and outlet ports of the expansion valve 24
is not in a one-phase liquid state and there are not the conditions
where cavitation noise in the expansion valve 24 remarkably
appears. As a result, only the process of the normal activation
control is performed prior to switching to the normal control
without performing the processes of step ST2 and ST3 in a case
where the cooling start noise reduction condition is not satisfied
in step ST1. In detail, the opening of the expansion valve 24 is
set as an activation opening Xni, the outdoor fan 36 is driven, and
the compressor 21 is driven by the operating frequency of the
compressor 21 being set to an activation frequency fni. Here, the
process of step ST4 is performed in approximately 10 seconds to 30
seconds (refer to time t6 in FIG. 5), and after this, the process
switches to the normal control.
[0095] On the other hand, in a case where the cooling start noise
reduction condition is satisfied in step ST1, the process moves to
step ST2 described below and the process of normal activation
control in step ST4 is performed after the processes of step ST2
and ST3 are performed.
[0096] <Step ST2>
[0097] In step ST2, the expansion valve refrigerant discharge
control, where the compressor 21 is driven in a state where the
outdoor fan 36 is stopped and the expansion valve 24 is open, is
performed. In detail, the compressor 21 is driven after
approximately 10 seconds to 30 seconds has elapsed (refer to time
t1 in FIG. 5) in a state where the outdoor fan 36 is stopped and
the expansion valve 24 is open. Due to this, it is possible to
create a state where liquid refrigerant has not accumulated at the
inlet and outlet ports of the expansion valve 24 by discharging
liquid refrigerant at expansion valve 24 and at the inlet and
outlet ports thereof to the indoor heat exchanger 41 side. That is,
it is possible for liquid refrigerant to flow smoothly to the
indoor heat exchanger 41 side while as little liquid refrigerant as
possible is supplied to the expansion valve 24 by suppressing
refrigerant condensing performance in the outdoor heat exchanger 23
due to the outdoor fan 36 being stopped and the expansion valve 24
being open when driving the compressor 21.
[0098] Here, liquid refrigerant smoothly flows through the
expansion valve 24 to the indoor heat exchanger 41 side in the
expansion valve refrigerant discharge control due to the expansion
valve 24 being open. However, at this time, there is a concern that
liquid refrigerant will return from the indoor heat exchanger 41
side to the compressor 21 via the gas refrigerant linking pipe 6,
the four way valve 22, and the like if operating frequency of the
compressor 21 is high. Therefore, here, the operating frequency of
the compressor 21 is set to a first noise reduction activation
frequency fevi1 which is less than an activation frequency fni
which is the operating frequency of the compressor 21 when starting
the cooling operation in a case where the cooling start noise
reduction condition is not satisfied. It is preferable that the
first noise reduction activation frequency fevi1 be set to an
operating frequency which is half or less of the activation
frequency fni. Due to this, it is possible to suppress the concern
that liquid refrigerant will return from the indoor heat exchanger
41 side to the compressor 21 while obtaining a smooth flow of
liquid refrigerant to the indoor heat exchanger 41 side in the
expansion valve refrigerant discharge control. Here, the operating
frequency of the compressor 21 may need not to be lower than the
activation frequency fni in a case where there is no concern that
the smooth flow of liquid refrigerant to the indoor heat exchanger
41 side will be impeded or concern that liquid refrigerant will
return from the indoor heat exchanger 41 side to the compressor 21
in the expansion valve refrigerant discharge control.
[0099] In addition, liquid refrigerant smoothly flows through the
expansion valve 24 to the indoor heat exchanger 41 side in the
expansion valve refrigerant discharge control due to the expansion
valve 24 being open. However, at this time, there is a concern that
flow path resistance when refrigerant passes through the expansion
valve 24 will be large if the opening of the expansion valve 24 is
small and smooth flow of liquid refrigerant to the indoor heat
exchanger 41 side will be impeded. Therefore, here, the opening of
the expansion valve 24 is set to a noise reduction activation
opening Xevi which is larger than an activation opening Xni when
starting the cooling operation in a case where the cooling start
noise reduction condition is not satisfied. It is preferable that
the noise reduction activation opening Xevi be set to an opening
which is double or more of the activation opening Xni. It is
possible to reliably obtain a smooth flow of liquid refrigerant to
the indoor heat exchanger 41 side with flow path resistance, when
refrigerant passes through the expansion valve 24, as small as
possible in the expansion valve refrigerant discharge control.
Here, the opening of the expansion valve 24 may need not to be
larger than the activation opening Xni in a case where there is no
concern that the smooth flow of liquid refrigerant to the indoor
heat exchanger 41 side will be impeded in the expansion valve
refrigerant discharge control.
[0100] Then, the process moves to the process of step ST3 after
approximately 10 seconds to 30 seconds has elapsed since driving
the compressor 21 (refer to time t2 in FIG. 5).
[0101] <Step ST3>
[0102] In step ST3, the expansion valve normal switching control,
where the opening of the expansion valve 24 is reduced and the
operating frequency of the compressor 21 is increased, is performed
after the expansion valve refrigerant discharge control in step
ST2. In detail, the opening of the expansion valve 24 is reduced to
the activation opening Xni when starting the cooling operation in a
case where the cooling start noise reduction condition is not
satisfied and the operating frequency of the compressor 21 is
increased to the activation frequency fni which is the operating
frequency of the compressor 21 when starting the cooling operation
in a case where the cooling start noise reduction condition is not
satisfied. Due to this, it is possible to suppress cavitation noise
in the expansion valve 24 by switching to normal control of the
expansion valve 24, that is, switching to normal control after
normal activation control in step ST4 in a state of having created
a state where liquid refrigerant has not accumulated at the inlet
and outlet ports of the expansion valve 24. In addition, there is a
tendency as in the present embodiment for it to be easy for
cavitation noise in the expansion valve 24 to be generated in a
case of providing the refrigerant circuit 10 where the expansion
valve 24 is in a positive cycle arrangement state, that is, in a
state with an arrangement where refrigerant flows in with a
horizontal orientation and refrigerant flows out in a downward
direction during the cooling operation. However, it is possible to
sufficiently suppress cavitation noise in the expansion valve 24
even if the expansion valve 24 is arranged in a positive cycle
arrangement state due to the expansion valve refrigerant discharge
control and the expansion valve normal switching control being
performed as described above.
[0103] In addition, a case is assumed where an action of reducing
the opening of the expansion valve 24 is performed after the
operating frequency of the compressor 21 is increased when
switching from the expansion valve refrigerant discharge control to
the expansion valve normal switching control. In this case, due to
the state, which is only temporary, where the operating frequency
of the compressor 21 is high in a state where the opening of the
expansion valve 24 is large, there is a concern that liquid
refrigerant will return from the indoor heat exchanger 41 side to
the compressor 21 via the gas refrigerant linking pipe 6, the four
way valve 22, and the like. Therefore, here, the opening of the
expansion valve 24 is reduced before the operating frequency of the
compressor 21 is increased when switching from the expansion valve
refrigerant discharge control to the expansion valve normal
switching control. In detail, the action of increasing the
operating frequency of the compressor 21 is performed after
approximately 5 seconds to 15 seconds has elapsed since performing
the action of reducing the opening of the expansion valve 24 (refer
to time t4 in FIG. 5). Due to this, it is possible to suppress the
concern that liquid refrigerant will return from the indoor heat
exchanger 41 side to the compressor 21 after the expansion valve
refrigerant discharge control. Here, the action of reducing the
opening of the expansion valve 24 before increasing the operating
frequency of the compressor 21 need not be performed in a case
where there is no concern that liquid refrigerant will return from
the indoor heat exchanger 41 side to the compressor 21.
[0104] In addition, a case is assumed where an action of reducing
the opening of the expansion valve 24 is performed while the
operating frequency of the compressor 21 is maintained as it is
when switching from the expansion valve refrigerant discharge
control to the expansion valve normal switching control. In this
case, there is a tendency for the pressure of refrigerant to be
raised at a portion of the refrigerant circuit 10 on the upstream
side of the expansion valve 24. If this is the case, there are
several concerns with a state where the inlet and outlet ports in
the expansion valve 24 are filled again with liquid refrigerant
even if a state is created where the flow rate of liquid
refrigerant which flows into the expansion valve 24 increases and
liquid refrigerant has not accumulated at the inlet and outlet
ports of the expansion valve 24 due to the expansion valve
refrigerant discharge control. Therefore, here, the opening of the
expansion valve 24 is reduced in a state where the operating
frequency of the compressor 21 is temporarily reduced when
switching from the expansion valve refrigerant discharge control to
the expansion valve normal switching control. In detail, the
operating frequency of the compressor 21 is reduced to a second
noise reduction activation frequency fevi2 which is lower than the
first noise reduction activation frequency fevi1 approximately 5
seconds to 15 seconds before the action of reducing the opening of
the expansion valve (refer to time t3 in FIG. 5). It is preferable
that the second noise reduction activation frequency fevi2 be, for
example, zero (the compressor 21 is stopped). Due to this, it is
possible to suppress a state where the inlet and outlet ports of
the expansion valve 24 are filled again with liquid refrigerant
after the expansion valve refrigerant discharge control by
suppressing the tendency for the pressure of refrigerant to be
raised at a portion of the refrigerant circuit 10 on the upstream
side of the expansion valve 24. Here, the state where the operating
frequency of the compressor 21 is reduced to the second noise
reduction activation frequency fevi2 is cancelled approximately 5
seconds to 15 seconds after the action of reducing the opening of
the expansion valve (refer to time t4 in FIG. 5). Then, the
operating frequency of the compressor 21 is operated so as to
increase to the activation frequency fni. Here, the action of
temporarily reducing the operating frequency of the compressor 21
when the opening of the expansion valve 24 is small need not be
performed in a case where there is no concern of a state where the
inlet and outlet ports of the expansion valve 24 are filled again
with liquid coolant.
[0105] Then, the process moves to the process of step ST4 after
approximately 20 seconds to 40 seconds has elapsed since increasing
the operating frequency of the compressor 21 (refer to time t5 in
FIG. 5).
[0106] In this manner, the cooling activation control (which
includes the expansion valve coolant discharge control and the
expansion valve normal switching control which are performed in a
case where the cooling start noise reduction condition is
satisfied) is performed in the air conditioner 1 of the present
embodiment. Then, due to this cooling activation control, it is
possible to sufficiently suppress cavitation noise in the expansion
valve 24 when starting the cooling operation under the low
temperature conditions.
INDUSTRIAL APPLICABILITY
[0107] It is possible for the present invention to be widely
applied with regard to air conditioners which perform a cooling
operation by driving an outdoor fan and circulating coolant in
order of a compressor, an outdoor heat exchanger, an expansion
valve, and an indoor heat exchanger.
REFERENCE SIGNS LIST
[0108] 1 AIR CONDITIONER [0109] 10 REFRIGERANT CIRCUIT [0110] 21
COMPRESSOR [0111] 23 OUTDOOR HEAT EXCHANGER [0112] 41 INDOOR HEAT
EXCHANGER [0113] 24 EXPANSION VALVE [0114] 36 OUTDOOR FAN
CITATION LIST
Patent Literature
[0114] [0115] PTL 1: Japanese Unexamined Patent Application
Publication No. 9-133434
* * * * *