U.S. patent application number 14/758588 was filed with the patent office on 2015-11-26 for air-conditioning apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Koji AZUMA, Katsuhiko HAYASHIDA, Osamu MORIMOTO, Hiroto NAKAO, Daisuke SHIMAMOTO, Akiyoshi SHIRAMIZU. Invention is credited to Koji AZUMA, Katsuhiko HAYASHIDA, Osamu MORIMOTO, Hiroto NAKAO, Daisuke SHIMAMOTO, Akiyoshi SHIRAMIZU.
Application Number | 20150338120 14/758588 |
Document ID | / |
Family ID | 51062223 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150338120 |
Kind Code |
A1 |
AZUMA; Koji ; et
al. |
November 26, 2015 |
AIR-CONDITIONING APPARATUS
Abstract
An air-conditioning apparatus includes a first branch unit, a
fourth flow control device arranged in each of a plurality of pipes
split from a first connection pipe side and connected to each
indoor-side heat exchanger, and a solenoid valve arranged in each
of pipes split from a pipe connecting each fourth flow control
device and each indoor-side heat exchanger. An opening degree of
the fourth flow control device is controlled based on a state of
refrigerant to be caused to flow into the fourth flow control
device.
Inventors: |
AZUMA; Koji; (Tokyo, JP)
; MORIMOTO; Osamu; (Tokyo, JP) ; NAKAO;
Hiroto; (Tokyo, JP) ; SHIRAMIZU; Akiyoshi;
(Tokyo, JP) ; HAYASHIDA; Katsuhiko; (Tokyo,
JP) ; SHIMAMOTO; Daisuke; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AZUMA; Koji
MORIMOTO; Osamu
NAKAO; Hiroto
SHIRAMIZU; Akiyoshi
HAYASHIDA; Katsuhiko
SHIMAMOTO; Daisuke |
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo
Chiyoda-ku, Tokyo |
|
JP
JP
US
JP
JP
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
51062223 |
Appl. No.: |
14/758588 |
Filed: |
January 7, 2013 |
PCT Filed: |
January 7, 2013 |
PCT NO: |
PCT/JP2013/050036 |
371 Date: |
June 30, 2015 |
Current U.S.
Class: |
62/196.1 |
Current CPC
Class: |
F25B 13/00 20130101;
F25B 2313/0272 20130101; F25B 2313/0314 20130101; F24F 11/83
20180101; F25B 2400/23 20130101; F24F 5/001 20130101; F25B 2400/13
20130101; F25B 2700/1931 20130101; F25B 2313/02741 20130101; F25B
2313/0233 20130101; F25B 2313/0231 20130101; F25B 2313/0253
20130101; F25B 2313/0252 20130101; F25B 2313/0311 20130101 |
International
Class: |
F24F 11/00 20060101
F24F011/00; F24F 5/00 20060101 F24F005/00 |
Claims
1. An air-conditioning apparatus, which is configured by connecting
a heat source unit and a plurality of indoor units through a first
connection pipe and a second connection pipe to supply refrigerant
from the heat source unit to each of the plurality of indoor units
to perform a cooling operation and/or a heating operation, the heat
source unit including a compressor, a switching valve, and a
heat-source-unit-side heat exchanger, each of the plurality of
indoor units including an indoor-side heat exchanger and a first
flow control device, the air-conditioning apparatus including: a
first branch unit for switchably connecting one of a refrigerant
inlet and a refrigerant outlet of the indoor-side heat exchanger of
each of the plurality of indoor units to the first connection pipe
or the second connection pipe; and a second branch unit connected
on one side thereof to the second connection pipe and split on an
other side thereof into a plurality of branches each connected to
an other one of the refrigerant inlet and the refrigerant outlet of
the indoor-side heat exchanger of each of the plurality of indoor
units through the first flow control device, the first branch unit
including: a branch-side flow control device provided to each of a
plurality of pipes split from the first connection pipe and
connected to the indoor-side heat exchanger of corresponding one of
the plurality of indoor units; and a solenoid valve provided to
each of pipes split from a pipe connecting the branch-side flow
control device and the indoor-side heat exchanger of corresponding
one of the plurality of indoor units, wherein an opening degree of
the branch-side flow control device is controlled based on a state
of the refrigerant to be caused to flow into the branch-side flow
control device, wherein the state of the refrigerant to be caused
to flow into the branch-side flow control device is determined
based on an outlet subcooling value of the indoor-side heat
exchanger that performs the heating operation before switching to
the cooling operation.
2-8. (canceled)
9. An air-conditioning apparatus, which is configured by connecting
a heat source unit and a plurality of indoor units through a first
connection pipe and a second connection pipe to supply refrigerant
from the heat source unit to each of the plurality of indoor units
to perform a cooling operation and/or a heating operation, the heat
source unit including a compressor, a switching valve, and a
heat-source-unit-side heat exchanger, each of the plurality of
indoor units including an indoor-side heat exchanger and a first
flow control device, the air-conditioning apparatus including: a
first branch unit for switchably connecting one of a refrigerant
inlet and a refrigerant outlet of the indoor-side heat exchanger of
each of the plurality of indoor units to the first connection pipe
or the second connection pipe; and a second branch unit connected
on one side thereof to the second connection pipe and split on an
other side thereof into a plurality of branches each connected to
an other one of the refrigerant inlet and the refrigerant outlet of
the indoor-side heat exchanger of each of the plurality of indoor
units through the first flow control device, the first branch unit
including: a branch-side flow control device provided to each of a
plurality of pipes split from the first connection pipe and
connected to the indoor-side heat exchanger of corresponding one of
the plurality of indoor units; and a solenoid valve provided to
each of pipes split from a pipe connecting the branch-side flow
control device and the indoor-side heat exchanger of corresponding
one of the plurality of indoor units, wherein an opening degree of
the branch-side flow control device is controlled based on a state
of the refrigerant to be caused to flow into the branch-side flow
control device, wherein the state of the refrigerant to be caused
to flow into the branch-side flow control device is determined by
estimating an inlet-outlet pressure difference of the branch-side
flow control device.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air-conditioning
apparatus to be used as, for example, a multi-air-conditioning
apparatus for a building, including a refrigerant circuit and
structure capable of efficiently supplying one or both of heating
energy and cooling energy generated by a heat source unit to a
plurality of loads.
BACKGROUND ART
[0002] Hitherto, air-conditioning apparatus such as a
multi-air-conditioning apparatus for a building are configured to
execute a cooling operation or a heating operation by circulating
refrigerant between, for example, an outdoor unit serving as a heat
source unit arranged outdoors and an indoor unit arranged indoors.
Specifically, an air-conditioned space is cooled or heated with air
that is cooled by refrigerant taking away heat or air that is
heated by refrigerant rejecting heat. As the refrigerant to be used
for such an air-conditioning apparatus, for example, a
hydrofluorocarbon (HFC)-based refrigerant is often used. In
addition, it is also suggested to use a natural refrigerant such as
carbon dioxide (CO.sub.2).
[0003] As such an air-conditioning apparatus, there is given an
air-conditioning apparatus capable of performing cooling and
heating operations by connecting a heat source unit and a plurality
of indoor units to supply refrigerant from the heat source unit to
each of the plurality of indoor units (see, for example, Patent
Literature 1). The air-conditioning apparatus as disclosed in
Patent Literature 1 includes a first branch unit (10) including
three-way switching valves (8) for switchably connecting first
connection pipes (6b, 6c, and 6d) and a first connection pipe (6)
or a second connection pipe (7), and a second branch unit (11) for
connecting second connection pipes (7b, 7c, and 7d) on an indoor
unit side and the second connection pipe (7) through check valves
(50b, 50c, 50d, 52b, 52c, and 52d).
[0004] In the air-conditioning apparatus as disclosed in Patent
Literature 1, each of the three-way switching valves (8) in the
first branch unit (10) switches refrigerant to be caused to flow
into the indoor unit intended for the heating operation and
refrigerant flowing in from the indoor unit that is performing the
cooling operation. In addition, each check valve constructing the
second branch unit (11) allows the refrigerant to unidirectionally
flow in accordance with the switching of the refrigerant in the
first branch unit (10). Therefore, when the indoor unit performs
the cooing operation, one of connection ports (first port 8a) of
the three-way switching valve (8) is closed, whereas two of the
connection ports (second port 8b and third port 8c) are opened. In
addition, when the indoor unit performs the heating operation, one
of the connection ports (second port 8b) is closed, whereas two of
the connection ports (first port 8a and third port 8c) are
opened.
[0005] In addition, when the indoor unit performs the cooling
operation, a pressure of the refrigerant is low in the first
connection pipe (6) and high in the second connection pipe (7).
Therefore, the pressure is high in a connection pipe on one
connection port (first port 8a) side of the three-way switching
valve (8) and low in a connection pipe on another connection port
(second port 8b) side. Further, the pressure is low in a connection
pipe on still another connection port (third port 8c) side. In
addition, during the cooling operation, the refrigerant is
controlled in accordance with an outlet superheating amount of an
indoor-side heat exchanger (5), and the refrigerant in a
low-pressure gas state flows in the first connection pipes (6b, 6c,
and 6d) on the indoor unit side.
[0006] Further, when the indoor unit performs the heating
operation, the pressure of the refrigerant is low in the first
connection pipe (6) and high in the second connection pipe (7).
Therefore, the pressure is high in the connection pipe on one
connection port (first port 8a) side of the three-way switching
valve (8) and low in the connection pipe on another connection port
(second port 8b) side. Further, the pressure is high in the
connection pipe on still another connection port (third port 8c)
side. In addition, during the heating operation, a flow rate of the
refrigerant is controlled in accordance with an outlet subcooling
amount of the indoor-side heat exchanger (5), and the refrigerant
in a high-temperature and high-pressure gas state flows in the
first connection pipes (6b, 6c, and 6d) on the indoor unit side.
The refrigerant in a high-temperature and high-pressure liquid
state is present in the indoor-side heat exchanger (5) and in a
connection pipe ranging from the indoor-side heat exchanger (5) to
first flow control devices (9).
[0007] Therefore, when the operation of the connected indoor unit
is switched from the heating operation to the cooling operation,
the high-temperature and high-pressure gas refrigerant and the
high-temperature and high-pressure liquid refrigerant that flow
during the heating operation pass through the three-way switching
valve (8) to flow into the first connection pipe (6), which is in a
low-pressure state. When the operation of the connected indoor unit
is switched from the heating operation to the cooing operation,
refrigerant flow noise is generated in the three-way switching
valve (8) depending on the balance between the high pressure and
the low pressure of the refrigerant that passes through the
three-way switching valve (8). In particular, the flow noise of the
high-temperature and high-pressure liquid refrigerant is
significant.
[0008] Thus, there is given an air-conditioning apparatus using
solenoid valves (solenoid opening/closing valves) in place of the
three-way switching valves (8) (see, for example, Patent Literature
2). In the air-conditioning apparatus as disclosed in Patent
Literature 2, a second solenoid valve (8b) is used for heating,
whereas a first solenoid valve (8a) and a third solenoid valve (8c)
with an orifice function are used for cooling. When the operation
is switched to the cooling operation, the refrigerant is caused to
flow into the first and third solenoid valves in a stepwise manner
to reduce the flow noise of the high-temperature and high-pressure
liquid refrigerant. In addition, in the air-conditioning apparatus
as disclosed in Patent Literature 2, the refrigerant flow noise is
reduced by reducing an opening diameter of the flow control device,
pulse-controlling the flow control device, or reducing an opening
diameter of the third solenoid valve.
[0009] In addition, there is also given another air-conditioning
apparatus downsized by using solenoid valves (solenoid
opening/closing valves) in place of the three-way switching valves
(8) (see FIG. 6). In this air-conditioning apparatus, a second
solenoid valve b is used for heating, whereas a first solenoid
valve a, a third solenoid valve c, and an orifice d are used for
cooling. In other words, in the air-conditioning apparatus as
illustrated in FIG. 6, the refrigerant is caused to flow into the
orifice d, the third solenoid valve c, and the first solenoid valve
a in a stepwise manner to reduce the flow noise of the
high-temperature and high-pressure liquid refrigerant when the
operation is switched to the cooling operation. Note that, in FIG.
6, the same reference signs are assigned to components
corresponding to those of the air-conditioning apparatus according
to an embodiment of the present invention.
CITATION LIST
Patent Literature
[0010] Patent Literature 1: Japanese Patent No. 4350836 (Embodiment
1, FIG. 1, etc.)
[0011] Patent Literature 2: Japanese Unexamined Patent Application
Publication No. Hei 09-042804 (FIG. 1, etc.)
SUMMARY OF INVENTION
Technical Problem
[0012] According to the air-conditioning apparatus as disclosed in
Patent Literature 2 and FIG. 6, one indoor unit requires three
solenoid valves, thereby being necessary to arrange as many
solenoid valves in the branch unit as the number of indoor units
multiplied by three. Pressure equalization is required to reduce
the refrigerant flow noise, but the control using solenoid valves
cannot achieve fine flow control. Thus, regardless of the pressure
state of the refrigerant that flows in from the connection pipe on
the indoor unit side, it is necessary to equalize the pressure on
the refrigerant over a given period of time, leading to failure to
optimize a startup time period of the indoor unit as well as
insufficient reduction of the refrigerant flow noise.
[0013] The present invention is to solve the problem as described
above, and an object of the present invention is to provide an
air-conditioning apparatus capable of enhancing comfort by reducing
a startup time period of an indoor unit while maintaining silence
in running.
Solution to Problem
[0014] According to one embodiment of the present invention, there
is provided an air-conditioning apparatus, which is configured by
connecting a heat source unit and a plurality of indoor units
through a first connection pipe and a second connection pipe to
supply refrigerant from the heat source unit to each of the
plurality of indoor units to perform a cooling operation and/or a
heating operation, the heat source unit including a compressor, a
switching valve, and a heat-source-unit-side heat exchanger, each
of the plurality of indoor units including an indoor-side heat
exchanger and a first flow control device, the air-conditioning
apparatus including: a first branch unit for switchably connecting
one of a refrigerant inlet and a refrigerant outlet of the
indoor-side heat exchanger of each of the plurality of indoor units
to the first connection pipe or the second connection pipe; and a
second branch unit connected on one side thereof to the second
connection pipe and split on an other side thereof into a plurality
of branches each connected to an other one of the refrigerant inlet
and the refrigerant outlet of the indoor-side heat exchanger of
each of the plurality of indoor units through the first flow
control device, the first branch unit including: a branch-side flow
control device provided to each of a plurality of pipes split from
the first connection pipe and connected to the indoor-side heat
exchanger of corresponding one of the plurality of indoor units;
and a solenoid valve provided to each of pipes split from a pipe
connecting the branch-side flow control device and the indoor-side
heat exchanger of corresponding one of the plurality of indoor
units, wherein an opening degree of the branch-side flow control
device is controlled based on a state of the refrigerant to be
caused to flow into the branch-side flow control device.
Advantageous Effects of Invention
[0015] According to the air-conditioning apparatus of the one
embodiment of the present invention, it is possible to determine an
appropriate opening degree of the branch-side flow control device
based on the state of the refrigerant to be cased to flow into the
branch-side flow control device, thereby being capable of reducing
the refrigerant flow noise and the startup time period of the
indoor unit as compared to the case of switching a plurality of
solenoid valves in a stepwise manner over a given period of time.
As a result, the comfort is enhanced.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is an overall configuration diagram focusing on a
refrigerant system of an air-conditioning apparatus according to an
embodiment of the present invention.
[0017] FIG. 2 illustrates an operation state of the
air-conditioning apparatus during cooling and heating operations
(cooling only operation) according to the embodiment of the present
invention.
[0018] FIG. 3 illustrates an operation state of the
air-conditioning apparatus during cooling and heating operations
(heating only operation) according to the embodiment of the present
invention.
[0019] FIG. 4 illustrates an operation state of the
air-conditioning apparatus during cooling and heating operations
(cooling main operation) according to the embodiment of the present
invention.
[0020] FIG. 5 illustrates an operation state of the
air-conditioning apparatus during cooling and heating operations
(heating main operation) according to the embodiment of the present
invention.
[0021] FIG. 6 is a circuit configuration diagram schematically
illustrating an example configuration of a relay unit of a
related-art air-conditioning apparatus.
[0022] FIG. 7 is a flowchart illustrating an example flow of
processing for controlling an opening degree of a fourth flow
control device 55 of the air-conditioning apparatus during a
refrigerant noise suppression operation according to the embodiment
of the present invention.
[0023] FIG. 8 is a flowchart illustrating an example flow of
processing for determining whether the refrigerant noise
suppression operation is necessary for the air-conditioning
apparatus according to the embodiment of the present invention.
[0024] FIG. 9 is a flowchart illustrating an example flow of
processing for determining whether the refrigerant noise
suppression operation is necessary for the air-conditioning
apparatus according to the embodiment of the present invention.
[0025] FIG. 10 is a flowchart illustrating an example flow of
processing for determining whether the refrigerant noise
suppression operation is necessary for the air-conditioning
apparatus according to the embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0026] Now, an embodiment of the present invention is described
referring to the drawings. Note that, in the drawings referred to
below including FIG. 1, the size relationship between components
may be different from the reality in some cases. Further, in the
drawings referred to below including FIG. 1, the same or
corresponding parts are represented by the same reference signs,
and the same applies hereinafter. Further, the forms of the
constituent elements described herein are only examples and the
present invention is not limited to the forms described.
[0027] FIG. 1 is an overall configuration diagram focusing on a
refrigerant system of an air-conditioning apparatus 100 according
to an embodiment of the present invention. In addition, FIGS. 2 to
5 illustrate an operation state of the air-conditioning apparatus
100 during cooling and heating operations. FIG. 2 is an operation
state diagram for a cooling only operation. FIG. 3 is an operation
state diagram for a heating only operation. FIG. 4 is an operation
state diagram for a cooling main operation in which cooling
operation capacity is larger than heating operation capacity in a
cooling and heating simultaneous operation. FIG. 5 is an operation
state diagram for a heating main operation in which heating
operation capacity is larger than cooling operation capacity in the
cooling and heating simultaneous operation. Note that, in this
embodiment, the case of connecting three indoor units to one heat
source unit is described, but the case of connecting two or more
indoor units is the same.
[0028] As illustrated in FIG. 1, the air-conditioning apparatus 100
includes a heat source unit A, indoor units B, C, and D
(hereinafter each simply referred to as "indoor unit" unless
otherwise mentioned), and a relay unit E, which are connected to
each other. The heat source unit A has a function to supply heating
energy or cooling energy to the indoor units. As described later,
the indoor units are connected to each other in parallel, and have
the same configuration. Each indoor unit has a function to execute
air-conditioning of an air-conditioned space such as an indoor
space by heating energy or cooling energy supplied from the heat
source unit A. The relay unit E is arranged between the heat source
unit A and the indoor units, and has a function to switch the flow
of refrigerant supplied from the heat source unit A in response to
a request from the indoor units.
[0029] The heat source unit A includes a compressor 1 with variable
capacity, a four-way switching valve 2 for switching a flow
direction of the refrigerant in the heat source unit A, a
heat-source-unit-side heat exchanger 3 that functions as an
evaporator or condenser (radiator), an accumulator 4 that is
connected to a suction side of the compressor 1 through the
four-way switching valve 2, a heat-source-unit-side fan 20 that can
change air-sending amount for sending air to the
heat-source-unit-side heat exchanger 3, and a heat-source-unit-side
switching valve 40 for limiting the flow direction of the
refrigerant. Further, those components construct the heat source
unit A. Note that, the four-way switching valve 2 corresponds to
the "switching valve" of the present invention. Note that, the
"switching valve" may include a combination of valves such as a
two-way valve and a three-way valve, instead of the four-way
switching valve.
[0030] The indoor unit includes an indoor-side heat exchanger 5
that functions as a condenser (radiator) or evaporator, and a first
flow control device 9 that is controlled in accordance with an
outlet-side superheating amount of the indoor-side heat exchanger 5
during cooling and is controlled in accordance with an outlet-side
subcooling amount of the indoor-side heat exchanger 5 during
heating. Further, those components construct the indoor unit.
[0031] The relay unit E includes, as built-in devices, a first
branch unit 10, a second flow control device 13, a second branch
unit 11, a gas-liquid separating device 12, heat exchange units
(first heat exchange unit 19 and second heat exchange unit 16), and
a third flow control device 15. Further, those components construct
the relay unit E.
[0032] The four-way switching valve 2 in the heat source unit A and
the relay unit E are connected by a thick first connection pipe
6.
[0033] The indoor-side heat exchanger 5 in the indoor unit and the
relay unit E are connected by a first connection pipe 6b, 6c, or 6d
on the indoor unit side, which corresponds to the first connection
pipe 6.
[0034] The heat-source-unit-side heat exchanger 3 in the heat
source unit A and the relay unit E are connected by a second
connection pipe 7 that is thinner than the first connection pipe
6.
[0035] The indoor-side heat exchanger 5 in the indoor unit and the
relay unit E are connected through the first connection pipe 6, and
are also connected by a second connection pipe 7b, 7c, or 7d on the
indoor unit side, which corresponds to the second connection pipe
7.
[0036] The first branch unit 10 has a function to switchably
connect the first connection pipes 6b, 6c, and 6d on the indoor
unit side and the first connection pipe 6 side or the second
connection pipe 7 side.
[0037] The first branch unit 10 includes fourth flow control
devices (branch-side flow control devices) 55 that are connected to
the respective first connection pipes 6b, 6c, and 6d on the indoor
unit side and to the first connection pipe 6, and solenoid valves
31 as valve devices that are connected to the respective first
connection pipes 6b, 6c, and 6d on the indoor unit side and to the
second connection pipe 7 side.
[0038] The second branch unit 11 has a function to switch the
connection between the second connection pipes 7b, 7c, and 7d on
the indoor unit side and the second connection pipe 7 in accordance
with the flow of the refrigerant.
[0039] The second branch unit 11 includes first check valves 50
(first check valves 50b, 50c, and 50d) described later, and second
check valves 52 (second check valves 52b, 52c, and 52d) described
later.
[0040] The gas-liquid separating device 12 is arranged in the
middle of the second connection pipe 7, and includes a gas-phase
portion connected to the solenoid valves 31 of the first branch
unit 10 and a liquid-phase portion connected to the second branch
unit 11.
[0041] The second flow control device 13 is arranged between the
gas-liquid separating device 12 and the second branch unit 11 on
the second connection pipe 7 and includes, for example, an electric
expansion valve that is openable and closable.
[0042] Note that, the second branch unit 11 and the first
connection pipe 6 are connected by a first bypass pipe 14.
[0043] The third flow control device 15 is arranged in the middle
of the first bypass pipe 14 and includes, for example, an electric
expansion valve that is openable and closable.
[0044] The second heat exchange unit 16 is arranged on a downstream
side of the third flow control device 15 on the first bypass pipe
14, and exchanges heat with a part on a downstream side of the
second flow control device 13 on the second connection pipe 7.
[0045] The first heat exchange unit 19 is arranged on a downstream
side of the second heat exchange unit 16 on the first bypass pipe
14, and exchanges heat with a part on an upstream side of the
second flow control device 13 on the second connection pipe 7.
[0046] The first check valves 50b, 50c, and 50d are arranged,
respectively, in the middle of the second connection pipes 7b, 7c,
and 7d on the indoor unit side in the second branch unit 11, and
allow the refrigerant to flow only from the second connection pipe
7 to the second connection pipes 7b, 7c, and 7d on the indoor unit
side.
[0047] Note that, a downstream part of the second check valves 52b,
52c, and 52d of the second connection pipes 7b, 7c, and 7d on the
indoor unit side, and a pipe portion on the downstream side of the
second flow control device 13 of the second connection pipe 7 and
on an upstream side of the second heat exchange unit 16 are
connected by a second bypass pipe 51. Further, a pipe in the second
bypass pipe 51 that is connected to the second connection pipes 7b,
7c, and 7d on the indoor unit side and a pipe in the second bypass
pipe 51 that is connected to the second connection pipe 7 join
together in the middle.
[0048] The second check valves 52b, 52c, and 52d are arranged in an
upstream part with respect to a part where the pipe in the middle
of the second bypass pipe 51 that is connected to the second
connection pipes 7b, 7c, and 7d on the indoor unit side, and the
pipe in the second bypass pipe 51 that is connected to the second
connection pipe 7 join together, and allow the refrigerant to flow
only from the second connection pipes 7b, 7c, and 7d on the indoor
unit side to the second connection pipe 7.
[0049] Note that, a first refrigerant passage is formed by a
passage that leads from the second connection pipe 7 to the first
flow control device 9 through the second connection pipes 7b, 7c,
and 7d on the indoor unit side including the first check valves
50b, 50c, and 50d. A second refrigerant passage is formed by a
passage that leads from the first flow control device 9 to the
second connection pipe 7 through the second connection pipes 7b,
7c, and 7d on the indoor unit side and the second bypass pipe 51
including the second check valves 52b, 52c, and 52d.
[0050] A third check valve 32 is arranged in the middle of a pipe
that connects the heat-source-unit-side heat exchanger 3 and the
second connection pipe 7, and allows the refrigerant to flow only
from the heat-source-unit-side heat exchanger 3 to the second
connection pipe 7.
[0051] A fourth check valve 33 is arranged in the middle of a pipe
that connects the four-way switching valve 2 in the heat source
unit A and the first connection pipe 6, and allows the refrigerant
to flow only from the first connection pipe 6 to the four-way
switching valve 2.
[0052] A fifth check valve 34 is arranged in the middle of a pipe
that connects the four-way switching valve 2 in the heat source
unit A and the second connection pipe 7, and allows the refrigerant
to flow only from the four-way switching valve 2 to the second
connection pipe 7.
[0053] A sixth check valve 35 is arranged in the middle of a pipe
that connects the heat-source-unit-side heat exchanger 3 and the
first connection pipe 6, and allows the refrigerant to flow only
from the first connection pipe 6 to the heat-source-unit-side heat
exchanger 3.
[0054] The third check valve 32, the fourth check valve 33, the
fifth check valve 34, and the sixth check valve 35 construct the
heat-source-unit-side switching valve 40.
[0055] The relay unit E includes first pressure detection means 25,
second pressure detection means 26, and third pressure detection
means 56.
[0056] The first pressure detection means 25 is arranged between
the first branch unit 10 and the second flow control device 13 on
the second connection pipe 7.
[0057] The second pressure detection means 26 is arranged between
the second flow control device 13 and the first flow control device
9.
[0058] The third pressure detection means 56 is arranged at a
position where the first connection pipe 6 and the first bypass
pipe 14 are connected.
[0059] The indoor unit includes first temperature detection means
53 and second temperature detection means 54.
[0060] The first temperature detection means 53 is arranged in the
indoor unit on the first branch unit 10 side.
[0061] The second temperature detection unit 54 is arranged in the
indoor unit on the second branch unit 11 side.
[0062] In other words, the first temperature detection means 53 and
the second temperature detection means 54 are arranged at both ends
of the indoor-side heat exchanger 5. The second temperature
detection means 54 is connected on the first flow control device 9
side, whereas the first temperature detection means 53 is connected
to the other end.
[0063] In addition, the heat-source-unit-side heat exchanger 3
includes a first heat-source-unit-side heat exchanger 41, a second
heat-source-unit-side heat exchanger 42, a heat-source-unit-side
bypass passage 43, a first solenoid opening/closing valve 44, a
second solenoid opening/closing valve 45, a third solenoid
opening/closing valve 46, a fourth solenoid opening/closing valve
47, and a fifth solenoid opening/closing valve 48. Note that, the
heat-source-unit-side heat exchanger 3 includes the
heat-source-unit-side fan 20 that controls heat exchange capacity
of the heat-source-unit-side heat exchanger 3.
[0064] The first heat-source-unit-side heat exchanger 41 and the
second heat-source-unit-side heat exchanger 42 have the same heat
transfer area and are connected in parallel to each other.
[0065] The heat-source-unit-side bypass passage 43 is connected in
parallel to the first heat-source-unit-side heat exchanger 41 and
the second heat-source-unit-side heat exchanger 42.
[0066] The first solenoid opening/closing valve 44 is arranged at
one end of the first heat-source-unit-side heat exchanger 41 on a
side connected to the four-way switching valve 2.
[0067] The second solenoid opening/closing valve 45 is arranged at
the other end of the first heat-source-unit-side heat exchanger
41.
[0068] The third solenoid opening/closing valve 46 is arranged at
one end of the second heat-source-unit-side heat exchanger 42 on a
side connected to the four-way switching valve 2.
[0069] The fourth solenoid opening/closing valve 47 is arranged at
the other end of the second heat-source-unit-side heat exchanger
42.
[0070] The fifth solenoid opening/closing valve 48 is arranged in
the middle of the heat-source-unit-side bypass passage 43.
[0071] In addition, the heat source unit A includes fourth pressure
detection means 18. The fourth pressure detection means 18 is
arranged in the middle of a pipe that connects the four-way
switching valve 2 and a discharge portion of the compressor 1.
[0072] The air-conditioning apparatus 100 includes a controller 70.
This controller 70 integrally controls the entire system of the
air-conditioning apparatus 100. Specifically, the controller 70
controls a driving frequency of the compressor 1, a rotation speed
of each of the heat-source-unit-side fan 20 and a fan arranged in
the indoor-side heat exchanger 5, switching of the four-way
switching valve 2, opening and closing of each solenoid valve, an
opening degree of each expansion device, and the like. In other
words, based on information detected by the temperature detection
means and the pressure detection means as described above and an
instruction from a remote controller (not shown), the controller 70
controls respective actuators (driving components for the
compressor 1, the four-way switching valve 2, each solenoid valve
(first solenoid opening/closing valve 44 to fifth solenoid
opening/closing valve 48, and solenoid valve 31), each expansion
device (first flow control device 9, second flow control device 13,
third flow control device 15, and fourth flow control device 55)
and the like).
[0073] Note that, a type of the refrigerant to be filled in the
air-conditioning apparatus 100 is not particularly limited, and,
for example, there may be used any of a natural refrigerant such as
carbon dioxide (CO.sub.2), a hydrocarbon, and helium, an
alternative refrigerant that does not contain chlorine, such as
HFC410A, HFC407C (zeotropic refrigerant mixture in which
HFC-R32/R125/R134a are mixed at a ratio of 23/25/52 wt %), and
HFC404A, and a fluorocarbon refrigerant such as R22 and R134a used
for existing products.
[0074] An example case where the heat-source-unit-side heat
exchanger 3 and the indoor-side heat exchanger 5 exchange heat
between refrigerant and air has been described, but the heat may
also be exchanged between refrigerant and a heat medium other than
air, for example, water and brine.
[0075] In addition, this embodiment describes an example case where
the air-conditioning apparatus 100 includes one heat source unit A,
but the present invention is not limited thereto. The
air-conditioning apparatus 100 may include two or more heat source
units A. Further, an example case where the air-conditioning
apparatus 100 includes three indoor units is described, but the
present invention is not limited thereto. The air-conditioning
apparatus 100 may include four or more indoor units. The controller
70 may be installed in any one of the heat source unit A, the
indoor unit, and the relay unit E, and may also be installed in all
of the heat source unit A, the indoor unit, and the relay unit E.
In addition, the controller 70 may also be installed separately
from the heat source unit A, the indoor unit, and the relay unit E.
In addition, in the case of constructing the controller 70 with a
plurality of components, the components are preferable to be
communicably connected to each other by wired or wireless
connection.
[0076] Next, an operation of the air-conditioning apparatus 100 is
described.
[Cooling Operation]
[0077] First, an operation state for the cooling only operation is
described referring to FIG. 2. FIG. 2 illustrates an example state
where the cooling operation is performed by all of the indoor units
B, C, and D.
[0078] As illustrated in FIG. 2, high-temperature and high-pressure
refrigerant gas discharged from the compressor 1 passes through the
four-way switching valve 2, and, in the heat-source-unit-side heat
exchanger 3, exchanges heat with air that is sent by the
heat-source-unit-side fan 20 that can change air-sending amount, to
thereby condense and liquefy. Subsequently, the refrigerant passes
sequentially through the third check valve 32, the second
connection pipe 7, the gas-liquid separating device 12, and the
second flow control device 13, and further through the second
branch unit 11 and the second connection pipes 7b, 7c, and 7d on
the indoor unit side to flow into the respective indoor units B, C,
and D.
[0079] Then, the refrigerant that flows into each of the indoor
units B, C, and D is decompressed to low pressure by the first flow
control device 9 that is controlled in accordance with the outlet
superheating amount of each indoor-side heat exchanger 5. The
decompressed refrigerant flows into the indoor-side heat exchanger
5, and exchanges heat with indoor air to evaporate and gasify,
thereby cooling the indoor space. Then, the refrigerant in this gas
state is sucked by the compressor 1 after passing through the first
connection pipes 6b, 6c, and 6d on the indoor unit side, the fourth
flow control devices 55 in the first branch unit 10, the first
connection pipe 6, the fourth check valve 33, the four-way
switching valve 2, and the accumulator 4 in the heat source unit.
In this way, the circulation cycle is constructed to perform the
cooling operation.
[0080] At this time, each solenoid valve 31 is controlled to be
closed. Further, because the first connection pipe 6 is at low
pressure and the second connection pipe 7 is at high pressure, the
refrigerant naturally flows into the third check valve 32 and the
fourth check valve 33.
[0081] In addition, the opening degree of the fourth flow control
device 55 is controlled based on the state of the refrigerant,
which is obtained by the detection information from the third
pressure detection means 56.
[0082] In addition, in this circulation cycle, a part of the
refrigerant after passing through the second flow control device 13
enters the first bypass pipe 14. Then, after decompressed to low
pressure by the third flow control device 15, the refrigerant
exchanges heat in the second heat exchange unit 16 with refrigerant
passing through the second flow control device 13 (refrigerant
before branching off to flow into the first bypass pipe 14), to
thereby evaporate. Further, in the first heat exchange unit 19, the
refrigerant exchanges heat with refrigerant before flowing into the
second flow control device 13, to thereby evaporate. This
evaporated refrigerant enters the first connection pipe 6 and the
fourth check valve 33, and passes through the four-way switching
valve 2 and the accumulator 4 in the heat source unit to be sucked
by the compressor 1.
[0083] On the other hand, the sufficiently-subcooled refrigerant,
which is cooled by exchanging heat in the first heat exchange unit
19 and the second heat exchange unit 16 with the refrigerant that
enters the first bypass pipe 14 and is decompressed to low pressure
by the third flow control device 15, passes through the first check
valves 50b, 50c, and 50d in the second branch unit 11 and flows
into the indoor units B, C, and D intended for cooling. Here, the
capacity of the compressor 1 and the air-sending amount of the
heat-source-unit-side fan 20, which are variable, are adjusted so
that the evaporating temperature of the indoor unit and the
condensing temperature of the heat-source-unit-side heat exchanger
3 reach predetermined target temperatures, thereby being capable of
obtaining target cooling capacity in each indoor unit. Note that,
the condensing temperature of the heat-source-unit-side heat
exchanger 3 can be obtained as saturation temperature for the
pressure detected by the fourth pressure detection means 18.
[Heating Operation]
[0084] Next, an operation state for the heating only operation is
described referring to FIG. 3. FIG. 3 illustrates an example state
where the heating operation is performed by all of the indoor units
B, C, and D.
[0085] As illustrated in FIG. 3, the high-temperature and
high-pressure refrigerant gas discharged from the compressor 1
passes sequentially through the four-way switching valve 2, the
fifth check valve 34, the second connection pipe 7, the gas-liquid
separating device 12, the solenoid valves 31 in the first branch
unit 10, and the first connection pipes 6b, 6c, and 6d on the
indoor unit side, and flows into the indoor units B, C, and D. The
refrigerant that flows into each of the indoor units B, C, and D
exchanges heat with indoor air to condense and liquefy, thereby
heating the indoor space. Then, the refrigerant in this state is
controlled in accordance with the outlet subcooling amount of each
indoor-side heat exchanger 5, and passes through the first flow
control device 9.
[0086] The refrigerant after passing through the first flow control
devices 9 flows from the second connection pipes 7b, 7c, and 7d on
the indoor unit side into the second branch unit 11, and joins
together after passing through the second check valves 52b, 52c,
and 52d. The refrigerant that joins together in the second branch
unit 11 is introduced further into the middle of the second
connection pipe 7 between the second flow control device 13 and the
second heat exchange unit 16, and passes through the third flow
control device 15. In addition, here, the refrigerant is
decompressed to low-pressure two-phase gas-liquid by the first flow
control device 9 or the third flow control device 15.
[0087] Then, the refrigerant decompressed to low pressure passes
through the first connection pipe 6 into the sixth check valve 35
and the heat-source-unit-side heat exchanger 3 in the heat source
unit A, and exchanges heat in the heat source unit A with air sent
by the heat-source-unit-side fan 20 that can change air-sending
amount, to thereby evaporate. The refrigerant in the gas state
resulting from the evaporation is sucked by the compressor 1 after
passing through the four-way switching valve 2 and the accumulator
4. In this way, the circulation cycle is constructed to perform the
heating operation.
[0088] At this time, each solenoid valve 31 is controlled to be
opened.
[0089] In addition, the fourth flow control device 55 is
closed.
[0090] In addition, because the first connection pipe 6 is at low
pressure and the second connection pipe 7 is at high pressure in
the circulation cycle, the refrigerant naturally flows into the
fifth check valve 34 and the sixth check valve 35. In addition,
because the pressure in the second connection pipes 7b, 7c, and 7d
on the indoor unit side is higher than the pressure in the second
connection pipe 7, the first check valves 50b, 50c, and 50d are
closed. Here, the capacity of the compressor 1 and the air-sending
amount of the heat-source-unit-side fan 20, which are variable, are
adjusted so that the condensing temperature of the indoor unit and
the evaporating temperature of the heat-source-unit-side heat
exchanger 3 reach predetermined target temperatures, thereby being
capable of obtaining target heating capacity in each indoor
unit.
[Cooling Main Operation]
[0091] Next, an operation state for the cooling main operation is
described referring to FIG. 4. FIG. 4 illustrates an example of the
cooling main operation in a case where there are a cooling request
from each of the indoor units B and C and a heating request from
the indoor unit D.
[0092] As illustrated in FIG. 4, the high-temperature and
high-pressure refrigerant gas discharged from the compressor 1
flows into the heat-source-unit-side heat exchanger 3 through the
four-way switching valve 2, and exchanges heat in the
heat-source-unit-side heat exchanger 3 with air sent by the
heat-source-unit-side fan 20 that can change air-sending amount,
thereby being brought into a two-phase high-temperature and
high-pressure state.
[0093] Here, the capacity of the compressor 1 and the air-sending
amount of the heat-source-unit-side fan 20, which are variable, are
adjusted so that the evaporating temperature and the condensing
temperature of the indoor unit reach predetermined target
temperatures. In addition, the heat transfer area is adjusted by
opening and closing the first solenoid opening/closing valve 44,
the second solenoid opening/closing valve 45, the third solenoid
opening/closing valve 46, and the fourth solenoid opening/closing
valve 47 at both ends of the first heat-source-unit-side heat
exchanger 41 and the second heat-source-unit-side heat exchanger
42. In addition, by opening and closing the fifth solenoid
opening/closing valve 48 in the heat-source-unit-side bypass
passage 43, a flow rate of the refrigerant that flows in the first
heat-source-unit-side heat exchanger 41 and the second
heat-source-unit-side heat exchanger 42 is adjusted. In this way,
it is possible to obtain an arbitrary heat exchange amount in the
heat-source-unit-side heat exchanger 3, and to obtain target
heating capacity or cooling capacity in each indoor unit.
[0094] Subsequently, the refrigerant in the two-phase
high-temperature and high-pressure state is sent to the gas-liquid
separating device 12 in the relay unit E through the third check
valve 32 and the second connection pipe 7, and is separated into
gas-state refrigerant and liquid-state refrigerant.
[0095] Then, the gas-state refrigerant separated by the gas-liquid
separating device 12 passes sequentially through the solenoid valve
31 in the first branch unit 10 and the first connection pipe 6d on
the indoor unit side, and flows into the indoor unit D that is
intended for heating. Then, the gas-state refrigerant exchanges
heat with indoor air by the indoor-side heat exchanger 5 to
condense and liquefy, thereby heating the indoor space. Further,
the refrigerant, which flows out of the indoor-side heat exchanger
5, passes through the first flow control device 9 that is
controlled in accordance with the outlet subcooling amount of the
indoor-side heat exchanger 5 in the indoor unit D to be
decompressed to a small extent, and flows into the second branch
unit 11. The refrigerant passes through the second bypass pipe 51
including the second check valve 52d, and flows into a downstream
part of the second flow control device 13 on the second connection
pipe 7.
[0096] On the other hand, the liquid-state refrigerant separated by
the gas-liquid separating device 12 passes through the second flow
control device 13 that is controlled in accordance with the
pressure detected by the first pressure detection means 25 and the
pressure detected by the second pressure detection means 26, and
joins the refrigerant passing through the indoor unit D intended
for heating. Subsequently, the refrigerant flows into the second
heat exchange unit 16 to be cooled by the second heat exchange unit
16.
[0097] Then, a part of the refrigerant cooled by the second heat
exchange unit 16 passes through the first check valves 50b and 50c
and the second connection pipes 7b and 7c on the indoor unit side,
and flows into the indoor units B and C intended for cooling. The
refrigerant that flows into each of the indoor units B and C enters
the first flow control device 9 that is controlled in accordance
with the outlet superheating amount of the indoor-side heat
exchanger 5 in each of the indoor units B and C to be decompressed,
and then enters the indoor-side heat exchanger 5 and exchanges heat
to evaporate into a gas state, thereby cooling the indoor space.
Subsequently, the refrigerant flows into the first connection pipe
6 through the fourth flow control device 55.
[0098] On the other hand, the rest of the refrigerant cooled by the
second heat exchange unit 16 passes through the third flow control
device 15 that is controlled so that a pressure difference between
the pressure detected by the first pressure detection means 25 and
the pressure detected by the second pressure detection means 26
falls within a predetermined range. Subsequently, after exchanging
heat and evaporating in the second heat exchange unit 16 and the
first heat exchange unit 19, the refrigerant flows into the thick
first connection pipe 6 and joins the refrigerant passing through
the indoor units B and C. The refrigerant that joins together in
the first connection pipe 6 is sucked by the compressor 1 after
passing through the fourth check valve 33, the four-way switching
valve 2, and the accumulator 4 in the heat source unit A. In this
way, the circulation cycle is constructed to perform the cooling
main operation.
[0099] At this time, the solenoid valves 31 connected to the indoor
units B and C are controlled to be closed, and the solenoid valve
31 connected to the indoor unit D is controlled to be opened.
[0100] In addition, the fourth flow control devices 55 connected to
the indoor units B and C are opened, and the fourth flow control
device 55 connected to the indoor unit D is closed.
[0101] In addition, because the first connection pipe 6 is at low
pressure and the second connection pipe 7 is at high pressure, the
refrigerant naturally flows into the third check valve 32 and the
fourth check valve 33.
[0102] Further, because the pressure in each of the second
connection pipes 7b and 7c on the indoor unit side is lower than
the pressure in the second connection pipe 7, the second check
valves 52b and 52c are closed.
[0103] In addition, because the pressure in the second connection
pipe 7d on the indoor unit side is higher than the pressure in the
second connection pipe 7, the first check valve 50d is closed.
[0104] The first check valves 50 and the second check valves 52
prevent the refrigerant, which passes through the indoor unit D
with a request for heating, from flowing into the indoor units B
and C with a request for cooling under a state in which the
refrigerant fails to be sufficiently subcooled without passing
through the second heat exchange unit 16.
[Heating Main Operation]
[0105] Next, an operation state for the heating main operation is
described referring to FIG. 5. FIG. 5 illustrates an example of the
heating main operation in a case where there are a heating request
from each of the indoor units B and C and a cooling request from
the indoor unit D.
[0106] As illustrated in FIG. 5, the high-temperature and
high-pressure refrigerant gas discharged from the compressor 1 is
sent to the relay unit E through the four-way switching valve 2,
the fifth check valve 34, and the second connection pipe 7, and
passes through the gas-liquid separating device 12. The refrigerant
passing through the gas-liquid separating device 12 passes
sequentially through the solenoid valves 31 in the first branch
unit 10 and the first connection pipes 6b and 6c on the indoor unit
side, and flows into the indoor units B and C intended for heating.
Then, the refrigerant exchanges heat with indoor air in each
indoor-side heat exchanger 5 to condense and liquefy, thereby
heating the indoor space. The refrigerant condensed and liquefied
is controlled in accordance with the outlet subcooling amount of
the indoor-side heat exchanger 5 in each of the indoor units B and
C, and passes through the first flow control device 9 to be
decompressed to a small extent. Then, the refrigerant flows into
the second branch unit 11.
[0107] The refrigerant that flows into the second branch unit 11
passes through the second bypass pipe 51 including the second check
valves 52b and 52c, and joins the refrigerant in the second
connection pipe 7 to be cooled in the second heat exchange unit 16.
A part of the refrigerant cooled by the second heat exchange unit
16 passes through the first check valve 50d and the second
connection pipe 7d on the indoor unit side, and enters the indoor
unit D intended for cooling. Then, the refrigerant after entering
the indoor unit D enters the first flow control device 9 that is
controlled in accordance with the outlet superheating amount of the
indoor-side heat exchanger 5 to be decompressed, and subsequently
enters the indoor-side heat exchanger 5 and exchanges heat to
evaporate into a gas state, thereby cooling the indoor space. Then,
the refrigerant flows into the first connection pipe 6 through the
fourth flow control device 55.
[0108] On the other hand, the rest of the refrigerant cooled by the
second heat exchange unit 16 passes through the third flow control
device 15 that is controlled so that the pressure difference
between the pressure detected by the first pressure detection means
25 and the pressure detected by the second pressure detection means
26 falls within the predetermined range. The refrigerant after
passing through the third flow control device 15 exchanges heat in
the second heat exchange unit 16 with refrigerant flowing out of
the heating indoor units, to thereby evaporate. Subsequently, the
refrigerant joins the refrigerant passing through the indoor unit D
intended for cooling, and flows into the sixth check valve 35 and
the heat-source-unit-side heat exchanger 3 in the heat source unit
A through the thick first connection pipe 6. The refrigerant that
flows into the heat-source-unit-side heat exchanger 3 exchanges
heat with air that is sent by the heat-source-unit-side fan 20 that
can change air-sending amount, to thereby evaporate into a gas
state.
[0109] Here, the capacity of the compressor 1 and the air-sending
amount of the heat-source-unit-side fan 20, which are variable, are
adjusted so that the evaporating temperature of the indoor unit D
with a request for cooling and the condensing temperature of each
of the indoor units B and C with a request for heating fall within
predetermined target temperatures. In addition, the heat transfer
area is adjusted by opening and closing the first solenoid
opening/closing valve 44, the second solenoid opening/closing valve
45, the third solenoid opening/closing valve 46, and the fourth
solenoid opening/closing valve 47 at both ends of the first
heat-source-unit-side heat exchanger 41 and the second
heat-source-unit-side heat exchanger 42. In addition, by opening
and closing the fifth solenoid opening/closing valve 48 in the
heat-source-unit-side bypass passage 43, the flow rate of the
refrigerant that flows in the first heat-source-unit-side heat
exchanger 41 and the second heat-source-unit-side heat exchanger 42
is adjusted. In this way, it is possible to obtain an arbitrary
heat exchange amount in the heat-source-unit-side heat exchanger 3,
and to obtain target heating capacity or cooling capacity in each
indoor unit. Then, the refrigerant is sucked by the compressor 1
after passing through the four-way switching valve 2 and the
accumulator 4 in the heat source unit A. In this way, the
circulation cycle is constructed to perform the heating main
operation.
[0110] At this time, the solenoid valves 31 connected to the indoor
units B and C are controlled to be opened, and the solenoid valve
31 connected to the indoor unit D is controlled to be closed. In
addition, the fourth flow control devices 55 connected to the
indoor units B and C are closed, and the fourth flow control device
55 connected to the indoor unit D is opened.
[0111] In addition, because the first connection pipe 6 is at low
pressure and the second connection pipe 7 is at high pressure, the
refrigerant naturally flows into the fifth check valve 34 and the
sixth check valve 35. At this time, the second flow control device
13 is closed.
[0112] Further, because the pressure in each of the second
connection pipes 7b and 7c on the indoor unit side is higher than
the pressure in the second connection pipe 7, the first check
valves 50b and 50c are closed.
[0113] In addition, because the pressure in the second connection
pipe 7d on the indoor unit side is lower than the pressure in the
second connection pipe 7, the second check valve 52d is closed.
[0114] The first check valves 50 and the second check valves 52
prevent the refrigerant, which pass through each of the heating
indoor units B and C, from flowing into the cooling indoor unit D
under a state in which the refrigerant fails to be sufficiently
subcooled without passing through the second heat exchange unit
16.
[Control of Opening Degree of Fourth Flow Control Device 55]
[0115] The opening degree of the fourth flow control device 55 is
controlled based on the state of the refrigerant, which is obtained
based on detection information from the third pressure detection
means 56. In other words, the controller 70 determines the state of
the refrigerant that flows into the fourth flow control device 55
based on pressure information detected by the third pressure
detection means 56 to appropriately maintain the opening degree of
the fourth flow control device 55 based on a result of the
determination.
[0116] Note that, the example above describes the case where the
state of the refrigerant that flows into the fourth flow control
device 55 is determined based on the detection information from the
third pressure detection means 56, but the present invention is not
limited thereto. Information from other detection means may also be
used as described below.
[0117] For example, the state of the refrigerant that flows into
the fourth flow control device 55 may also be determined by
estimating a pressure difference value at an inlet and outlet of
the fourth flow control device 55 based on the information from the
third pressure detection means 56 and the first temperature
detection means 53 (see FIG. 8).
[0118] In addition, the state of the refrigerant that flows into
the fourth flow control device 55 may also be determined based on
the outlet subcooling value of the indoor-side heat exchanger 5
that performs the heating operation before switching to the cooling
operation (see FIG. 9).
[0119] Further, the state of the refrigerant that flows into the
fourth flow control device 55 may also be determined by estimating
the state of the refrigerant in the idle indoor unit based on an
elapsed time period since the stop of heating (see FIG. 10).
[0120] Still further, the state of the refrigerant that flows into
the fourth flow control device 55 may also be determined by
combining those methods.
[0121] FIG. 7 is a flowchart illustrating an example flow of
processing for controlling the opening degree of the fourth flow
control device 55 during a refrigerant noise suppression operation.
FIGS. 8 to 10 are flowcharts each illustrating an example flow of
processing for determining whether or not the refrigerant noise
suppression operation is necessary. Referring to FIGS. 7 to 10, the
refrigerant noise suppression operation in the fourth flow control
device 55 is described. Note that, the controller 70 is a main
controller in FIGS. 7 to 10.
[0122] First, referring to FIG. 7, the flow of the processing
during the refrigerant noise suppression operation is
described.
[0123] When the refrigerant noise suppression operation is started
(Step S101), the controller 70 controls the opening degree of the
fourth flow control device 55 to be slightly opened (Step S102).
Then, the controller 70 determines whether or not the refrigerant
noise suppression operation is necessary (Step S103). Whether or
not the refrigerant noise suppression operation is necessary is
determined in accordance with the flowcharts of FIGS. 8 to 10
described later.
[0124] When it is determined that the refrigerant noise suppression
operation is necessary (Step S103; YES), the controller 70
increases the opening degree of the fourth flow control device 55
(Step S104). Next, the controller 70 determines whether or not the
opening degree of the fourth flow control device 55 is at a maximum
(Max opening degree) (Step S105). On the other hand, when it is
determined that the refrigerant noise suppression operation is not
necessary (Step S103; NO), the controller 70 finishes the
refrigerant noise suppression operation (Step S106).
[0125] When it is determined that the opening degree of the fourth
flow control device 55 is at a maximum (Step S105; YES), the
controller 70 finishes the refrigerant noise suppression operation
(Step S106). On the other hand, when it is determined that the
opening degree of the fourth flow control device 55 is not at a
maximum (Step S105; NO), the controller 70 reconfirms whether or
not the refrigerant noise suppression operation is necessary (Step
S103).
[0126] Next, referring to FIG. 8, an example flow of processing for
determining whether or not the refrigerant noise suppression
operation is necessary is described. In FIG. 8, whether or not the
refrigerant noise suppression operation is necessary is determined
based on a front and back pressure difference of the fourth flow
control device 55.
[0127] When determining (reconfirming) whether or not the
refrigerant noise suppression operation is necessary (Step S103 in
FIG. 7 and Step S101a), the controller 70 determines whether or not
a front and back pressure difference .DELTA.Pa of the fourth flow
control device 55 is equal to or greater than a predetermined
target pressure difference .DELTA.P0 (Step S102a). Then, when
.DELTA.Pa is equal to or greater than .DELTA.P0 (Step S102a; YES),
the controller 70 determines that the refrigerant noise suppression
operation is necessary (Step S104a). On the other hand, when
.DELTA.Pa is smaller than .DELTA.P0 (Step S102a; NO), the
controller 70 finishes the refrigerant noise suppression operation
and returns to a regular operation (Step S103a).
[0128] Note that, for pressure on a low pressure side of the fourth
flow control device 55, the third pressure detection means 56 only
needs to be used. In addition, for pressure on a high pressure side
of the fourth flow control device 55, the saturation temperature on
the indoor unit side may be estimated by using the first
temperature detection means 53.
[0129] Next, referring to FIG. 9, an example flow of processing for
determining whether or not the refrigerant noise suppression
operation is necessary is described. In FIG. 9, whether or not the
refrigerant noise suppression operation is necessary is determined
based on subcooling in the indoor unit during the heating
operation.
[0130] When determining (reconfirming) whether or not the
refrigerant noise suppression operation is necessary (Step S103 in
FIG. 7 and Step S101b), the controller 70 determines whether or not
subcooling SCa in the indoor unit during the heating operation is
equal to or greater than predetermined target subcooling SC0 (Step
S102b). Then, when SCa is equal to or greater than SC0 (Step S102b;
YES), the controller 70 determines that the refrigerant noise
suppression operation is necessary (Step S104b). On the other hand,
when SCa is smaller than SC0 (Step S102b; NO), the controller 70
finishes the refrigerant noise suppression operation and returns to
the regular operation (Step S103b).
[0131] Note that, the saturation temperature of the indoor unit
during the heating operation may be estimated by using the first
pressure detection means 25. In addition, a subcooling value (SC
value) may be calculated based on the saturation temperature
estimated by using the second temperature detection means 54 and
the first pressure detection means 25.
[0132] Next, referring to FIG. 10, an example flow of processing
for determining whether or not the refrigerant noise suppression
operation is necessary is described. In FIG. 10, whether or not the
refrigerant noise suppression operation is necessary is determined
based on the elapsed time period since the end of the heating
operation.
[0133] When determining (reconfirming) whether or not the
refrigerant noise suppression operation is necessary (Step S103 in
FIG. 7 and Step S101c), the controller 70 determines whether or not
an elapsed time period Ta since the end of the heating operation is
equal to or greater than a predetermined target elapsed time period
TO (Step S102c). Then, when Ta is equal to or greater than TO (Step
S102c; YES), the controller 70 determines that the refrigerant
noise suppression operation is necessary (Step S104c). On the other
hand, when Ta is smaller than TO (Step S102c; NO), the controller
70 finishes the refrigerant noise suppression operation and returns
to the regular operation (Step S103c).
[0134] Whether or not the refrigerant noise suppression operation
is necessary is described above separately referring to the
flowcharts of FIGS. 8 to 10, but whether or not the refrigerant
noise suppression operation is necessary may also be determined by
combining those methods as appropriate.
[0135] As described above, according to the air-conditioning
apparatus 100, the opening degree of the fourth flow control device
55 can be maintained in an appropriate state, thereby being capable
of significantly reducing the refrigerant flow noise that may be
generated when the heating operation is switched to the cooling
operation as compared to the configuration in which the first
branch unit includes a plurality of solenoid valves. In addition,
according to the air-conditioning apparatus 100, it is not
necessary to equalize the refrigerant pressure regardless of the
amount of the high-temperature and high-pressure liquid refrigerant
flowing from the first connection pipe 6 on the indoor unit side,
thereby being capable of reducing the startup time period of the
indoor unit. Thus, according to the air-conditioning apparatus 100,
it is possible to significantly enhance comfort.
REFERENCE SIGNS LIST
[0136] 1 compressor [0137] 2 four-way switching valve [0138] 3
heat-source-unit-side heat exchanger [0139] 4 accumulator [0140] 5
indoor-side heat exchanger [0141] 6 first connection pipe [0142] 6b
first connection pipe [0143] 6d first connection pipe [0144] 7
second connection pipe [0145] 7b second connection pipe [0146] 7d
second connection pipe [0147] 9 first flow control device [0148] 10
first branch unit [0149] 11 second branch unit [0150] 12 gas-liquid
separating device [0151] 13 second flow control device [0152] 14
first bypass pipe [0153] 15 third flow control device [0154] 16
second heat exchange unit [0155] 18 fourth pressure detection means
[0156] 19 first heat exchange unit [0157] 20 heat-source-unit-side
fan [0158] 25 first pressure detection means [0159] 26 second
pressure detection means [0160] 31 solenoid valve [0161] 32 third
check valve [0162] 33 fourth check valve [0163] 34 fifth check
valve [0164] 35 sixth check valve [0165] 40 heat-source-unit-side
switching valve [0166] 41 first heat-source-unit-side heat
exchanger [0167] 42 second heat-source-unit-side heat exchanger
[0168] 43 heat-source-unit-side bypass passage [0169] 44 first
solenoid opening/closing valve [0170] 45 second solenoid
opening/closing valve [0171] 46 third solenoid opening/closing
valve [0172] 47 fourth solenoid opening/closing valve [0173] 48
fifth solenoid opening/closing valve [0174] 50 first check valve
[0175] 50b first check valve [0176] 50c first check valve [0177]
50d first check valve [0178] 51 second bypass pipe [0179] 52 second
check valve [0180] 52b second check valve [0181] 52d second check
valve [0182] 53 first temperature detection means [0183] 54 second
temperature detection means [0184] 55 fourth flow control device
[0185] 56 third pressure detection means [0186] 70 control device
[0187] 100 air-conditioning apparatus [0188] A heat source unit
[0189] B indoor unit [0190] C indoor unit [0191] D indoor unit
[0192] E relay unit
* * * * *