U.S. patent application number 17/826801 was filed with the patent office on 2022-09-15 for air conditioning system.
This patent application is currently assigned to DAIKIN INDUSTRIES, LTD.. The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Junya MINAMI.
Application Number | 20220290885 17/826801 |
Document ID | / |
Family ID | 1000006420309 |
Filed Date | 2022-09-15 |
United States Patent
Application |
20220290885 |
Kind Code |
A1 |
MINAMI; Junya |
September 15, 2022 |
AIR CONDITIONING SYSTEM
Abstract
An air conditioning system includes a refrigerant circuit, a
heat exchanger, a shutoff valve, and a refrigerant leakage sensor.
The refrigerant circuit includes a first part and a second part.
The heat exchanger is provided in the first part and exchanges heat
between a refrigerant and air in an air conditioning target space.
The shutoff valve is provided in the refrigerant circuit and shuts
off communication between the first part and the second part. The
refrigerant leakage sensor detects that refrigerant concentration
is within a first range and detects the refrigerant leaked from the
first part. The shutoff valve is placed to set the refrigerant
concentration in the air conditioning target space within a second
range larger than the first range, when it is assumed that all the
refrigerant present in the first part has leaked to the air
conditioning target space.
Inventors: |
MINAMI; Junya; (Osaka-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka |
|
JP |
|
|
Assignee: |
DAIKIN INDUSTRIES, LTD.
Osaka
JP
|
Family ID: |
1000006420309 |
Appl. No.: |
17/826801 |
Filed: |
May 27, 2022 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2020/043893 |
Nov 25, 2020 |
|
|
|
17826801 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 49/005 20130101;
F25B 41/24 20210101; F24F 11/36 20180101 |
International
Class: |
F24F 11/36 20060101
F24F011/36; F25B 49/00 20060101 F25B049/00; F25B 41/24 20060101
F25B041/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2019 |
JP |
2019-217391 |
Claims
1. An air conditioning system comprising: a refrigerant circuit
including a first part and a second part; a heat exchanger provided
in the first part and configured to cool or heat air in an air
conditioning target space by exchanging heat between a refrigerant
and the air in the air conditioning target space; a shutoff valve
provided in the refrigerant circuit and configured to shut off
communication between the first part and the second part; and a
refrigerant leakage sensor configured to detect the refrigerant
leaked from the first part, wherein the refrigerant leakage sensor
detects that refrigerant concentration is within a first range, and
the shutoff valve is placed to set the refrigerant concentration in
the air conditioning target space within a second range that is a
range larger than the first range when it is assumed that all the
refrigerant present in the first part has leaked to the air
conditioning target space.
2. The air conditioning system according to claim 1, wherein when a
lower limit concentration of combustion of the refrigerant is LFL
[kg/m.sup.3], the first range is from LFL/X1 to LFL/X2, the second
range is from LFL/Y1 to LFL/Y2, and X1 is larger than Y1, and X2 is
larger than Y2.
3. The air conditioning system according to claim 1, wherein the
refrigerant circuit includes a utilization-side refrigerant flow
path that is part of the first part, a heat source-side refrigerant
flow path that is part of the second part, and a first connection
flow path and a second connection flow path connecting the
utilization-side refrigerant flow path to the heat source-side
refrigerant flow path, the shutoff valve includes a first shutoff
valve provided in the first connection flow path and a second
shutoff valve provided in the second connection flow path, the
first connection flow path includes a utilization-side first
connection flow path between the utilization-side refrigerant flow
path and the first shutoff valve, and a heat source-side first
connection flow path between the heat source-side refrigerant flow
path and the first shutoff valve, the second connection flow path
includes a utilization-side second connection flow path between the
utilization-side refrigerant flow path and the second shutoff
valve, and a heat source-side second connection flow path between
the heat source-side refrigerant flow path and the second shutoff
valve, and the first shutoff valve and the second shutoff valve are
placed based on volume of the utilization-side refrigerant flow
path, volume of the utilization-side first connection flow path,
volume of the utilization-side second connection flow path, and
volume of the air conditioning target space.
4. The air conditioning system according to claim 2, wherein the
refrigerant circuit includes a utilization-side refrigerant flow
path that is part of the first part, a heat source-side refrigerant
flow path that is part of the second part, and a first connection
flow path and a second connection flow path connecting the
utilization-side refrigerant flow path to the heat source-side
refrigerant flow path, the shutoff valve includes a first shutoff
valve provided in the first connection flow path and a second
shutoff valve provided in the second connection flow path, the
first connection flow path includes a utilization-side first
connection flow path between the utilization-side refrigerant flow
path and the first shutoff valve, and a heat source-side first
connection flow path between the heat source-side refrigerant flow
path and the first shutoff valve, the second connection flow path
includes a utilization-side second connection flow path between the
utilization-side refrigerant flow path and the second shutoff
valve, and a heat source-side second connection flow path between
the heat source-side refrigerant flow path and the second shutoff
valve, and the first shutoff valve and the second shutoff valve are
placed based on volume of the utilization-side refrigerant flow
path, volume of the utilization-side first connection flow path,
volume of the utilization-side second connection flow path, and
volume of the air conditioning target space.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of PCT International
Application No. PCT/2020/043893, filed on Nov. 25, 2020, which
claims priority under 35 U.S.C. 119(a) to Patent Application No.
2019-217391, filed in Japan on Nov. 29, 2019, all of which are
hereby expressly incorporated by reference into the present
application.
TECHNICAL FIELD
[0002] The present disclosure relates to an air conditioning
system.
BACKGROUND ART
[0003] Patent Literature 1 (Japanese Laid-Open Patent Application
No. 2019-45129) discloses an air conditioning system in which a
shutoff valve is connected to the outside of a utilization-side
unit. The shutoff valve is a part to be closed when a refrigerant
leakage is detected, and shuts off the flow between a heat
source-side unit and the utilization-side unit to prevent all the
refrigerant filled in a refrigerant circuit of the air conditioning
system from leaking.
SUMMARY
[0004] An air conditioning system of a first aspect includes a
refrigerant circuit, a heat exchanger, a shutoff valve, and a
refrigerant leakage sensor. The refrigerant circuit includes a
first part and a second part. The heat exchanger is provided in the
first part, and cools or heats air in an air conditioning target
space by exchanging heat between a refrigerant and the air in the
air conditioning target space. The shutoff valve is provided in the
refrigerant circuit and shuts off communication between the first
part and the second part. The refrigerant leakage sensor detects
the refrigerant leaked from the first part. The refrigerant leakage
sensor detects that refrigerant concentration is within a first
range. The shutoff valve is placed to set the refrigerant
concentration in the air conditioning target space within a second
range larger than the first range, when it is assumed that all the
refrigerant present in the first part has leaked to the air
conditioning target space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a diagram showing a schematic configuration of an
air conditioning system as one embodiment of a refrigerant cycle
device.
[0006] FIG. 2 is a control block diagram of the air conditioning
system.
[0007] FIG. 3 is a control flowchart when a refrigerant leaks
[0008] FIG. 4 is a schematic configuration diagram of the air
conditioning system according to Modification A.
[0009] FIG. 5 is a schematic configuration diagram of the air
conditioning system according to Modification B.
[0010] FIG. 6 is a schematic configuration diagram of the air
conditioning system according to Modification E.
DESCRIPTION OF EMBODIMENT
[0011] With reference to the drawings, an air conditioning system
100 according to one embodiment of the present disclosure will be
described below.
[0012] (1) Overall Configuration
[0013] (1-1) Air Conditioning System
[0014] The outline of the air conditioning system 100 including an
air conditioning apparatus 1 according to one embodiment will be
described with reference to FIG. 1. FIG. 1 is a schematic
configuration diagram of the air conditioning system 100. The air
conditioning apparatus 1 of the air conditioning system 100 is an
apparatus that performs vapor compression refrigeration cycle and
cools and heats air conditioning target space. The air conditioning
target space is, for example, an office or a living room in a
house. In the present embodiment, the air conditioning apparatus 1
is an apparatus that can both cool and heat the air conditioning
target space. However, the air conditioning apparatus 1 of the
present disclosure is not limited to the air conditioning apparatus
capable of both cooling and heating, and may be, for example, an
apparatus capable of only cooling.
[0015] The air conditioning apparatus 1 of the air conditioning
system 100 mainly includes a heat source-side unit 2, a plurality
of utilization-side units 3a, 3b, and 3c, a first connection flow
path 21, a second connection flow path 22, and a control unit 19
(see FIG. 2). The plurality of utilization-side units 3a, 3b, and
3c is connected in parallel to the heat source-side unit 2. The
first connection flow path 21 and the second connection flow path
22 connect the heat source-side unit 2 to the utilization-side
units 3a, 3b, and 3c via a shutoff valve 70. The first connection
flow path 21 and the second connection flow path 22 are laid at an
installation site of the air conditioning apparatus 1. The pipe
diameter and the pipe length of the first connection flow path 21
and the second connection flow path 22 are selected according to
the design specification and the installation environment. The
control unit 19 controls the heat source-side unit 2, the
utilization-side units 3a, 3b, and 3c, and the shutoff valve 70. A
vapor compression refrigerant circuit 10 of the air conditioning
apparatus 1 is configured by connecting a heat source-side
refrigerant flow path 14 of the heat source-side unit 2 to
utilization-side refrigerant flow paths 13a, 13b, and 13c of the
utilization-side units 3a, 3b, and 3c by the first connection flow
path 21 and the second connection flow path 22 via the shutoff
valve 70. The heat source-side refrigerant flow path 14 is a
refrigerant flow path provided inside the heat source-side unit 2.
The utilization-side refrigerant flow paths 13a, 13b, and 13c are
refrigerant flow paths provided inside the utilization-side units
3a, 3b, and 3c, respectively. The first connection flow path 21
includes utilization-side first connection flow paths 21aa, 21ab,
and 21ac and a heat source-side first connection flow path 21b. As
shown in FIG. 1, the utilization-side first connection flow paths
21aa, 21ab, and 21ac and the heat source-side first connection flow
path 21b are divided by first shutoff valves 71a, 71b, and 71c,
respectively. The second connection flow path 22 includes
utilization-side second connection flow paths 22aa, 22ab, and 22ac
and a heat source-side second connection flow path 22b. As shown in
FIG. 1, the utilization-side second connection flow paths 22aa,
22ab, and 22ac and the heat source-side second connection flow path
22b are divided by second shutoff valves 72a, 72b, and 72c,
respectively. The shutoff valve 70 is disposed in the refrigerant
circuit 10. The shutoff valve 70 includes the first shutoff valves
71a, 71b, and 71c and the second shutoff valves 72a, 72b, and
72c.
[0016] Although not restrictive, the refrigerant circuit 10 is
filled with a flammable refrigerant. The flammable refrigerant
includes the refrigerant categorized as Class 3 (higher
flammability), Class 2 (lower flammability), and Subclass 2L
(slight flammability) according to the standards of ASHRAE 34,
Designation and safety classification of refrigerant in the Unites
States or the standards of ISO 817, Refrigerants--designation and
safety classification. For example, as the refrigerant, any one of
R1234yf, R1234ze(E), R516A, R445A, R444A, R454C, R444B, R454A,
R455A, R457A, R459B, R452B, R454B, R447B, R32, R447A, R446A, and
R459A is adopted. In the present embodiment, the refrigerant to use
is R32. If R32 leaks from the refrigerant circuit 10 to the air
conditioning target space (inside room) and the refrigerant
concentration in the room increases, a combustion accident may
occur due to the flammability of the refrigerant. It is required to
prevent this combustion accident.
[0017] Note that the air conditioning system 100 and the air
conditioning apparatus 1 of the present disclosure are also useful
when the refrigerant is not flammable.
[0018] The configuration of the air conditioning system 100
including the air conditioning apparatus 1 will be described in
detail below.
[0019] (2) Detailed Configuration
[0020] (2-1) Refrigerant Circuit
[0021] The refrigerant circuit 10 of the air conditioning apparatus
1 is divided by the plurality of first shutoff valves 71a, 71b, and
71c and the plurality of second shutoff valves 72a, 72b, and 72c
into a plurality of first parts 11a, 11b, and 11c and a second part
12. Note that since the first shutoff valve 71a and the first
shutoff valves 71b and 71c have similar configurations, only the
configuration of the first shutoff valve 71a is described here. The
description of the configurations of the first shutoff valves 71b
and 71c is omitted, and instead of the subscript "a" indicating
each part of the first shutoff valve 71a, the subscripts "b" and
"c" are added, respectively. The second shutoff valves 72a, 72b,
and 72c and the first parts 11a, 11b, and 11c are described in a
similar manner.
[0022] The first shutoff valve 71a is a shutoff valve that shuts
off the flow of the liquid refrigerant flowing inside the first
connection flow path 21 under the control of the control unit 19.
The first connection flow path 21 is divided by the first shutoff
valve 71a into the utilization-side first connection flow path 21aa
and the heat source-side first connection flow path 21b. The first
shutoff valve 71a is connected to the liquid side of the
utilization-side refrigerant flow path 13a by the utilization-side
first connection flow path 21aa. The first shutoff valve 71a is
connected to the heat source-side refrigerant flow path 14 by the
heat source-side first connection flow path 21b.
[0023] The second shutoff valve 72a is a shutoff valve that shuts
off the flow of the gas refrigerant flowing inside the second
connection flow path 22 under the control of the control unit 19.
The second connection flow path 22 is divided by the second shutoff
valve 72a into the utilization-side second connection flow path
22aa and the heat source-side second connection flow path 22b. The
second shutoff valve 72a is connected to the gas side of the
utilization-side refrigerant flow path 13a by the utilization-side
second connection flow path 22aa. The second shutoff valve 72a is
connected to the heat source-side refrigerant flow path 14 by the
heat source-side second connection flow path 22b.
[0024] The first shutoff valves 71a, 71b, and 71c and the second
shutoff valves 72a, 72b, and 72c may be disposed near the
utilization-side units 3a, 3b, and 3c, but may be disposed away
from the utilization-side units 3a, 3b, and 3c, respectively.
Alternatively, as will be described in Modification E, the first
shutoff valves 71a, 71b, and 71c and the second shutoff valves 72a,
72b, and 72c may be disposed inside a casing of the
utilization-side units 3a, 3b, and 3c, respectively.
[0025] As shown in FIG. 1, the first parts 11a, 11b, and 11c refer
to utilization-side parts in the refrigerant circuit 10 divided by
the first shutoff valves 71a, 71b, and 71c and the second shutoff
valves 72a, 72b, and 72c, respectively. The first part 11a includes
the utilization-side refrigerant flow path 13a, the
utilization-side first connection flow path 21aa, and the
utilization-side second connection flow path 22aa. The detailed
configuration of the utilization-side refrigerant flow path 13a
will be described later. The utilization-side first connection flow
path 21aa is part of the first connection flow path 21. The
utilization-side first connection flow path 21aa connects the
utilization-side refrigerant flow path 13a to the first shutoff
valve 71a. The utilization-side second connection flow path 22aa is
part of the second connection flow path 22. The utilization-side
second connection flow path 22aa connects the utilization-side
refrigerant flow path 13a to the second shutoff valve 72a.
[0026] As shown in FIG. 1, the second part 12 refers to a heat
source-side part in the refrigerant circuit 10 divided by the first
shutoff valves 71a, 71b, and 71c and the second shutoff valves 72a,
72b, and 72c. The second part 12 includes the heat source-side
refrigerant flow path 14, the heat source-side first connection
flow path 21b, and the heat source-side second connection flow path
22b. The detailed configuration of the heat source-side refrigerant
flow path 14 will be described later. The heat source-side first
connection flow path 21b is part of the first connection flow path
21. The heat source-side first connection flow path 21b connects
the heat source-side refrigerant flow path 14 to the first shutoff
valve 71a. The heat source-side second connection flow path 22b is
part of the second connection flow path 22. The heat source-side
second connection flow path 22b connects the heat source-side
refrigerant flow path 14 to the second shutoff valve 72a.
[0027] As will be described in detail later, if a refrigerant
leakage occurs in the first part 11a, the control unit 19 causes
the first shutoff valve 71a and the second shutoff valve 72a to
shut off the refrigerant flow between the first part 11a and the
second part 12. If the refrigerant flow between the first part 11a
and the second part 12 is shut off, the total amount of refrigerant
that may flow from the first part 11a into the air conditioning
target space is equal to the total amount of refrigerant filled in
the first part 11a.
[0028] The utilization-side unit 3 and the heat source-side unit 2
constituting part of the first part 11a and the second part 12 will
be described below.
[0029] (2-2) Utilization-Side Unit
[0030] The utilization-side units 3a, 3b, and 3c are installed in
the air conditioning target space such as in a room of a building.
As described above, the utilization-side refrigerant flow paths
13a, 13b, and 13c of the utilization-side units 3a, 3b, and 3c are
connected to the heat source-side unit 2 via the first connection
flow path 21, the second connection flow path 22, and the shutoff
valve 70, and constitutes part of the refrigerant circuit 10.
[0031] The configuration of the utilization-side units 3a, 3b, and
3c will be described. Note that since the utilization-side unit 3a
and the utilization-side units 3b and 3c have similar
configurations, only the configuration of the utilization-side unit
3a will be described here. The description of the configurations of
the utilization-side units 3b and 3c is omitted, and instead of the
subscript "a" indicating each part of the utilization-side unit 3a,
the subscripts "b" and "c" are added, respectively. However, the
utilization-side units 3a, 3b, and 3c do not have to have similar
configurations, and for example, the capacity of the
utilization-side units 3a, 3b, and 3c may be different from each
other. The number of utilization-side units is not limited to
three, and may be one, two, or three or more.
[0032] The utilization-side unit 3a mainly includes a
utilization-side expansion valve 34a and a utilization-side heat
exchanger (heat exchanger) 30a. Note that although detailed
description is omitted, the utilization-side unit 3a includes a
casing, and various constituent devices of the utilization-side
unit 3a are housed inside the casing of the utilization-side unit
3a.
[0033] The utilization-side unit 3a includes the utilization-side
refrigerant flow path 13a provided inside the utilization-side unit
3a. The utilization-side refrigerant flow path 13a includes the
utilization-side heat exchanger (heat exchanger) 30a placed inside
the utilization-side unit 3a, the utilization-side expansion valve
34a, and a utilization-side liquid refrigerant pipe 37a connecting
the liquid side end of the utilization-side heat exchanger (heat
exchanger) 30a to the utilization-side expansion valve 34a.
[0034] The utilization-side expansion valve 34a is an electrically
powered expansion valve configured to adjust the flow rate of
refrigerant flowing in the utilization-side heat exchanger (heat
exchanger) 30a while decompressing the refrigerant, and is provided
in the utilization-side liquid refrigerant pipe 37a. Note that the
utilization-side expansion valve 34a is not limited to the
electrically powered expansion valve, and may be another type of
expansion valve such as a temperature automatic expansion
valve.
[0035] The utilization-side heat exchanger (heat exchanger) 30a is
a heat exchanger that functions as a refrigerant evaporator to cool
indoor air, or functions as a refrigerant radiator to heat indoor
air. The utilization-side heat exchanger (heat exchanger) 30a,
which is not limited in terms of type, is a fin-and-tube heat
exchanger including a plurality of heat transfer tubes and a
plurality of fins, for example. Here, the utilization-side unit 3a
includes a utilization-side fan 36a. The utilization-side fan 36a
supplies the utilization-side heat exchanger (heat exchanger) 30a
with indoor air as a cooling source or a heating source for the
refrigerant flowing in the utilization-side heat exchanger (heat
exchanger) 30a. The utilization-side fan 36a is, for example, a
centrifugal fan such as a turbo fan or a sirocco fan. The
utilization-side fan 36a is, but is not limited to, an
inverter-controlled fan, for example.
[0036] The utilization-side unit 3a is provided with various
sensors, although illustration is omitted. The sensors (not shown)
include, but are not limited to, a sensor that detect the
temperature of the refrigerant at the liquid side end of the
utilization-side heat exchanger (heat exchanger) 30a, a sensor that
detects the temperature of the refrigerant at the gas side end of
the utilization-side heat exchanger (heat exchanger) 30a, a
temperature sensor that measures the temperature in the air
conditioning target space, and the like. The utilization-side unit
3a is provided with a refrigerant leakage sensor 50a that detects a
refrigerant leakage. The refrigerant leakage sensor 50a in the
present disclosure is configured to detect the refrigerant having
refrigerant concentration in the range of LFL/X1 to LFL/X2. As the
refrigerant leakage sensor 50a, for example, a semiconductor gas
sensor or a detection unit that detects a sharp drop in the
refrigerant pressure inside the utilization-side unit 3a can be
adopted. When the semiconductor gas sensor is used, the
semiconductor gas sensor is connected to a utilization-side control
unit 93a (see FIG. 2). When the detection unit that detects a sharp
drop in the refrigerant pressure is adopted, a pressure sensor is
installed in the refrigerant pipe, and the utilization-side control
unit 93a is provided with detection algorithm to determine
refrigerant leakage from a change in a value of the sensor.
[0037] Note that here, the refrigerant leakage sensor 50a is
provided in the utilization-side unit 3a, but the present
disclosure is not limited to this example. The refrigerant leakage
sensor 50a may be provided in a remote controller for operating the
utilization-side unit 3a, in the air conditioning target space
where the utilization-side unit 3a performs air conditioning, or
the like.
[0038] (2-3) Heat Source-Side Unit
[0039] The heat source-side unit 2 is installed outside a structure
such as a building, for example, on the roof or on the ground. As
described above, the heat source-side refrigerant flow path 14 of
the heat source-side unit 2 is connected to the utilization-side
units 3a, 3b, and 3c via the first connection flow path 21, the
second connection flow path 22, and the shutoff valve 70, and
constitutes part of the refrigerant circuit 10.
[0040] The heat source-side unit 2 mainly includes a compressor 25,
a heat source-side heat exchanger 23, a switching mechanism 15, a
first closing valve 17a, and a second closing valve 17b. Note that
although detailed description is omitted, the heat source-side unit
2 includes a casing, and various constituent devices of the heat
source-side unit 2 are housed inside the casing of the heat
source-side unit 2. The switching mechanism 15 switches between a
cooling operation state in which the heat source-side heat
exchanger 23 functions as a refrigerant radiator and the
utilization-side heat exchangers (heat exchangers) 30a, 30b, and
30c function as refrigerant evaporators, and a heating operation
state in which the heat source-side heat exchanger 23 functions as
a refrigerant evaporator and the utilization-side heat exchangers
(heat exchangers) 30a, 30b, and 30c function as refrigerant
radiators.
[0041] The heat source-side refrigerant flow path 14 of the heat
source-side unit 2 includes, as refrigerant pipes, a suction pipe
31, a discharge pipe 32, a heat source-side first gas refrigerant
pipe 33, a heat source-side liquid refrigerant pipe 38, and a heat
source-side second gas refrigerant pipe 35 (see FIG. 1). The
suction pipe 31 connects the switching mechanism 15 to the suction
side of the compressor 25. The discharge pipe 32 connects the
discharge side of the compressor 25 to the switching mechanism 15.
The heat source-side first gas refrigerant pipe 33 connects the
switching mechanism 15 to the gas side end of the heat source-side
heat exchanger 23. The heat source-side liquid refrigerant pipe 38
connects the liquid side end of the heat source-side heat exchanger
23 to the first closing valve 17a. A heat source-side expansion
valve 26 is provided in the heat source-side liquid refrigerant
pipe 38. The heat source-side second gas refrigerant pipe 35
connects the switching mechanism 15 to the second closing valve
17b.
[0042] The compressor 25 sucks and compresses the low-pressure gas
refrigerant in the refrigeration cycle, and discharges the
high-pressure gas refrigerant in the refrigeration cycle. The
compressor 25 is, for example, an inverter-controlled compressor.
However, the compressor 25 may be a constant speed compressor.
[0043] The switching mechanism 15 is a device that can switch the
flow of refrigerant in the refrigerant circuit 10, and includes,
for example, a four-way switching valve. When the heat source-side
heat exchanger 23 functions as a refrigerant radiator and the
utilization-side heat exchangers (heat exchangers) 30a, 30b, and
30c function as refrigerant evaporators (in the cooling operation
state), the switching mechanism 15 connects the discharge side of
the compressor 25 to the gas side of the heat source-side heat
exchanger 23 (see the solid line of the switching mechanism 15 in
FIG. 1). When the heat source-side heat exchanger 23 functions as a
refrigerant evaporator and the utilization-side heat exchangers
(heat exchangers) 30a, 30b, and 30c function as refrigerant
radiators (in the heating operation state), the switching mechanism
15 connects the suction side of the compressor 25 to the gas side
of the heat source-side heat exchanger 23 (see the broken line of
the switching mechanism 15 in FIG. 1). Note that the switching
mechanism 15 may be implemented without using the four-way
switching valve. For example, the switching mechanism 15 may be
configured by combining a plurality of electromagnetic valves and
pipes so as to implement switching of the refrigerant flow
direction as described above.
[0044] The heat source-side heat exchanger 23 is a heat exchanger
that functions as a refrigerant radiator or functions as a
refrigerant evaporator. The heat source-side heat exchanger 23 is,
but is not limited to, a fin-and-tube heat exchanger including a
plurality of heat transfer tubes and a plurality of heat transfer
fins, for example. Here, the heat source-side unit 2 includes a
heat source-side fan 24. The heat source-side fan 24 sucks outdoor
air into the heat source-side unit 2, causes the sucked outdoor air
to exchange heat with the refrigerant in the heat source-side heat
exchanger 23, and discharges the air to the outside. The heat
source-side fan 24 is driven by a heat source-side fan motor. The
heat source-side fan 24 is, for example, an inverter-controlled
fan. However, the heat source-side fan 24 may be a constant speed
fan.
[0045] In the cooling operation, the air conditioning apparatus 1
of the air conditioning system 100 causes the refrigerant to flow
from the heat source-side heat exchanger 23 to the utilization-side
heat exchangers (heat exchangers) 30a, 30b, and 30c, each
functioning as a refrigerant evaporator, through the first
connection flow path 21. In the heating operation, the air
conditioning apparatus 1 causes the refrigerant to flow from the
compressor 25 to the utilization-side heat exchangers (heat
exchangers) 30a, 30b, and 30c, each functioning as a refrigerant
radiator, through the second connection flow path 22. In the
cooling operation, the switching mechanism 15 switches to the
cooling operation state, the heat source-side heat exchanger 23
functions as a refrigerant radiator, and the refrigerant flows from
the heat source-side unit 2 side to the utilization-side units 3a,
3b, and 3c side through the first connection flow path 21. In the
heating operation, the switching mechanism 15 switches to the
heating operation state, the refrigerant flows from the
utilization-side units 3a, 3b, and 3c side to the heat source-side
unit 2 side through the first connection flow path 21, and the heat
source-side heat exchanger 23 functions as a refrigerant
evaporator.
[0046] Here, the heat source-side liquid refrigerant pipe 38 is
provided with the heat source-side expansion valve 26. The heat
source-side expansion valve 26 is an electrically powered expansion
valve configured to decompress the refrigerant in the heating
operation, and is provided at a portion near the liquid side end of
the heat source-side heat exchanger 23 in the heat source-side
liquid refrigerant pipe 38. Note that the heat source-side
expansion valve 26 is not limited to the electrically powered
expansion valve, and may be another type of expansion valve such as
a temperature automatic expansion valve.
[0047] The heat source-side unit 2 is provided with various
sensors, although illustration is omitted. The sensors provided in
the heat source-side unit 2 include, but are not limited to, a
temperature sensor and a pressure sensor placed in the suction pipe
31 and the discharge pipe 32, a temperature sensor placed in the
heat source-side heat exchanger 23 and the heat source-side liquid
refrigerant pipe 38, a temperature sensor for measuring the
temperature of heat source air, and the like. However, the heat
source-side unit 2 does not have to include all of these
sensors.
[0048] (2-4) Control Unit
[0049] The control unit 19 is configured by connecting a heat
source-side control unit 92 to the utilization-side control units
93a, 93b, and 93c via a transmission line 90, as shown in FIG. 2.
The heat source-side control unit 92 controls constituent devices
of the heat source-side unit 2. The utilization-side control units
93a, 93b, and 93c control constituent devices of the
utilization-side units 3a, 3b, and 3c, the first shutoff valves
71a, 71b, and 71c, and the second shutoff valves 72a, 72b, and 72c,
respectively. The heat source-side control unit 92 included in the
heat source-side unit 2, and the utilization-side control units
93a, 93b, and 93c included in the utilization-side units 3a, 3b,
and 3c exchange information such as control signals with one
another via the transmission line 90.
[0050] The heat source-side control unit 92 includes a control
board on which electrical components such as a microcomputer and a
memory are mounted, and is connected to, for example, various
constituent devices 15, 17a, 17b, 23, 24, 25, 26 of the heat
source-side unit 2, various sensors (not shown), and the like. The
utilization-side control units 93a, 93b, and 93c each include a
control board on which electrical components such as a
microcomputer and a memory are mounted, and for example, various
constituent devices 30a, 30b, 30c, 34a, 34b, 34c, 36a, 36b, 36c of
the utilization-side units 3a, 3b, and 3c, various shutoff valves
71a, 71b, 71c, 72a, 72b, and 72c, refrigerant leakage sensors 50a,
50b, and 50c, various sensors (not shown), and the like are
connected.
[0051] In this way, the control unit 19 controls the operation of
the entire air conditioning apparatus 1. Specifically, based on
detection signals of various sensors (not shown) as described
above, the refrigerant leakage sensors 50a, 50b, and 50c, and the
like, the control unit 19 controls various constituent devices 15,
17a, 17b, 23, 24, 25, 26, 30a, 30b, 30c, 34a, 34b, 34c, 36a, 36b,
36c, 71a, 71b, 71c, 72a, 72b, and 72c of the air conditioning
apparatus 1.
[0052] (3) Operation of Air Conditioning Apparatus when Refrigerant
Leaks
[0053] Next, the operation of the air conditioning apparatus 1 when
a refrigerant leaks will be described with reference to FIG. 3. In
a similar manner to the basic operation described above, the
operation of the air conditioning apparatus 1 described below when
a refrigerant leaks is performed by the control unit 19 that
controls the constituent devices of the air conditioning apparatus
1.
[0054] Since similar control is performed even if the refrigerant
leaks in any of the first parts 11a, 11b, and 11c, the case where
the refrigerant leakage is detected in the first part 11a will be
described here as an example.
[0055] In step S1 of FIG. 3, it is determined whether any of the
refrigerant leakage sensors 50a, 50b, and 50c of the
utilization-side units 3a, 3b, and 3c has detected a refrigerant
leakage. Here, when the refrigerant leakage sensor 50a of the
utilization-side unit 3a detects the refrigerant leakage in the
first part 11a, the process proceeds to next step S2.
[0056] In step S2, in the first part 11a where the refrigerant
leaks, an alarm is issued to a person in the space where the
utilization-side unit 3a is installed (air conditioning target
space) by using an alarm device (not shown) that issues an alarm
with an alarm sound such as a buzzer and turns on light.
[0057] Next, in step S3, the first shutoff valve 71a and the second
shutoff valve 72a, which are shutoff valves corresponding to the
first part 11a where the refrigerant leaks, are closed.
Accordingly, the upstream side and the downstream side of the first
shutoff valve 71a and the second shutoff valve 72a are separated
from each other, and the refrigerant flow between the first part
11a and the second part 12 discontinues. As a result, the inflow of
refrigerant from the second part 12 or the first parts 11b and 11c
to the first part 11a discontinues.
[0058] (4) Method of Determining Position to Place Refrigerant
Shutoff Valve
[0059] (4-1)
[0060] If the refrigerant leaks in the first part 11a, all the
refrigerant filled in the refrigerant circuit 10 may leak to the
air conditioning target space. Therefore, when the refrigerant
leakage sensor 50a detects the refrigerant leakage, the control
unit 19 shuts off the first shutoff valve 71a and the second
shutoff valve 72a. Since the refrigerant flow between the first
part 11a and the second part 12 is shut off accordingly, all the
refrigerant filled in the refrigerant circuit 10 is prevented from
leaking to the air conditioning target space. In this case, the
total amount of refrigerant contained in the first part 11a is the
total amount of refrigerant considered to leak to the air
conditioning target space. The maximum value of the total amount of
refrigerant contained in the first part 11a can be calculated from
the volume of the utilization-side refrigerant flow path 13a, the
volume of the utilization-side first connection flow path 21aa, and
the volume of the utilization-side second connection flow path
22aa. As the volume of the utilization-side refrigerant flow path
13a, the volume of the utilization-side first connection flow path
21aa, and the volume of the utilization-side second connection flow
path 22aa increase, the maximum value of the total amount of
refrigerant contained in the first part 11a increases.
[0061] If the amount of refrigerant contained in the first part 11a
is large and the volume of the air conditioning target space is
small, the refrigerant concentration of the refrigerant leaked to
the air conditioning target space may be large. In other words, if
the volume of the utilization-side refrigerant flow path 13a, the
volume of the utilization-side first connection flow path 21aa, and
the volume of the utilization-side second connection flow path 22aa
are large, and if the volume of the air conditioning target space
is small, the refrigerant concentration of the refrigerant R32 near
the floor of the air conditioning target space may become large and
exceed the LFL/safety factor. Note that the lower flammability
limit (LFL) is minimum refrigerant concentration specified by ISO
817 and enabling flame propagation in a state where a refrigerant
and air are mixed uniformly. Therefore, the first shutoff valve 71a
and the second shutoff valve 72a need to be placed at positions
where there is no risk of exceeding the LFL/safety factor of the
air conditioning target space even if all the refrigerant present
in the first part 11a leaks to the air conditioning target
space.
[0062] (4-2) Second Range
[0063] The refrigerant circuit 10 of the air conditioning apparatus
1 is divided by the first shutoff valve 71a and the second shutoff
valve 72a into the first part 11a and the second part 12. The first
part 11a includes the utilization-side refrigerant flow path 13a,
the utilization-side first connection flow path 21aa, and the
utilization-side second connection flow path 22aa. The total amount
of refrigerant contained in the first part 11a is the total amount
of refrigerant that is considered to leak to the air conditioning
target space. The maximum value of the total amount of refrigerant
contained in the first part 11a can be calculated from the volume
of the utilization-side refrigerant flow path 13a, the volume of
the utilization-side first connection flow path 21aa, and the
volume of the utilization-side second connection flow path 22aa. In
other words, the maximum value of the total amount of refrigerant
contained in the first part 11a changes depending on the positions
where the first shutoff valve 71a and the second shutoff valve 72a
are placed in the refrigerant circuit 10. For example, when the
first shutoff valve 71a and the second shutoff valve 72a are placed
away from the position of the utilization-side unit 3a in the
refrigerant circuit 10, the volume of the utilization-side first
connection flow path 21aa and the volume of the utilization-side
second connection flow path 22aa are large, and therefore the
maximum value of the total amount of refrigerant contained in the
first part 11a is large.
[0064] If a refrigerant leakage occurs in the first part 11a, the
refrigerant concentration of the refrigerant leaked to the air
conditioning target space changes depending on the positions where
the first shutoff valve 71a and the second shutoff valve 72a are
placed in the refrigerant circuit 10. In the present disclosure,
the first shutoff valve 71a and the second shutoff valve 72a are
placed at positions where the refrigerant concentration in the air
conditioning target space is within the second range when it is
assumed that all the refrigerant present in the first part 11a at a
predetermined temperature, a predetermined pressure, and a
predetermined phase state leaks to the air conditioning target
space. The second range is a range of refrigerant concentration in
which it is considered that the occurrence of combustion accident
caused by the refrigerant leakage in the air conditioning target
space can be inhibited. The second range is from LFL/Y1 to LFL/Y2.
Y1 and Y2 are safety factors. When the second range is B, the
second range is, but is not limited to, LFL/100<B<LFL/1, for
example. Even if the refrigerant leakage occurs in the first part
11a and the refrigerant leaks to the air conditioning target space,
the occurrence of combustion accident is inhibited when the
refrigerant concentration in the air conditioning target space is
within the second range.
[0065] (4-3) First Range
[0066] As described above, if the refrigerant leakage occurs in the
first part 11a, after the refrigerant leakage sensor 50a detects
the refrigerant leakage, the control unit 19 causes the first
shutoff valve 71a and the second shutoff valve 72a to shut off the
flow of refrigerant between the first part 11a and the second part
12. In other words, only after the refrigerant leakage sensor 50a
detects the refrigerant leakage, the control unit 19 can cause the
first shutoff valve 71a and the second shutoff valve 72a to shut
off the flow of refrigerant between the first part 11a and the
second part 12.
[0067] Therefore, if the refrigerant concentration that can be
detected by the refrigerant leakage sensor 50a is larger than
concentration in the second range, it is considered that an amount
of refrigerant exceeding the second range leaks from the first part
11a to the air conditioning target space before the first shutoff
valve 71a and the second shutoff valve 72a shut off the flow
between the first part 11a and the second part 12.
[0068] In view of the above-described circumstances, the
refrigerant leakage sensor 50a is configured to detect the
refrigerant having refrigerant concentration in the first range
smaller than the refrigerant concentration in the second range. The
first range is from LFL/X1 to LFL/X2. X1 and X2 are safety factors.
When the first range is A, the first range is, but is not limited
to, LFL/100.ltoreq.A.ltoreq.LFL/4, for example.
[0069] In general, combustion accidents in the air conditioning
target space caused by a refrigerant leakage occur because a large
amount of refrigerant that exceeds the lower limit concentration of
combustion in the air conditioning target space leaks to the air
conditioning target space. The refrigerant leakage sensor 50a in
the present disclosure can detect the refrigerant having
refrigerant concentration within the first range. The refrigerant
concentration of the refrigerant in the first range is smaller than
the refrigerant concentration of the refrigerant in the second
range. In other words, the refrigerant leakage sensor 50a can
detect even a refrigerant having small (thin) refrigerant
concentration. This allows the control unit 19 to control the first
shutoff valve 71a and the second shutoff valve 72a such that the
refrigerant concentration in the air conditioning target space is
within the second range after the refrigerant leakage sensor 50a
detects the refrigerant leakage.
[0070] (4-4) Relationship Between First Range and Second Range
[0071] As described above, the second range is a range of
refrigerant concentration in which it is considered that the
occurrence of combustion accident caused by the refrigerant leakage
in the air conditioning target space can be inhibited. As described
above, if the refrigerant leakage sensor 50a cannot detect the
refrigerant having refrigerant concentration in the second range,
the refrigerant exceeding the second range may leak to the air
conditioning target space.
[0072] Therefore, in the present disclosure, it is determined that
X1 for the first range is larger than Y1 for the second range, and
that X2 for the first range is larger than Y2 for the second range.
In other words, the numerical value to be substituted for X1 for
the first range is larger than the numerical value to be
substituted for Y1 for the second range, and the numerical value to
be substituted for X2 for the first range is larger than the
numerical value to be substituted for Y2 for the second range. For
example, if the safety factor X1 for the first range is 50 and the
safety factor X2 is 4, the safety factor Y1 for the second range
is, for example, 49, and the safety factor Y2 is, for example, 1.
In this way, the refrigerant concentration in the first range is
definitely smaller than the refrigerant concentration in the second
range, and the refrigerant leakage sensor 50a can detect the
refrigerant leakage before the amount of refrigerant exceeding the
second range leaks to the air conditioning target space.
[0073] X1 being larger than Y1 and X2 being larger than Y2 mean
that, in other words, LFL/Y1 is refrigerant concentration larger
than LFL/X1, and LFL/Y2 is refrigerant concentration larger than
LFL/X2. In other words again, this means that LFL/Y1 is darker in
refrigerant concentration than LFL/X1, and LFL/Y2 is darker in
refrigerant concentration than LFL/X2. Therefore, if the first
range is A and the second range is B, it can be said that the first
range and the second range are ranges that satisfy the following
formulas.
LFL/100.ltoreq.A.ltoreq.LFL/4 (Formula 1):
LFL/100<B<LFL/1 (Formula 2):
[0074] When A and B satisfy Formulas 1 and 2, the refrigerant
leakage sensor 50a can detect the refrigerant in the second
range.
[0075] (4-5) Method of Determining Position to Place Refrigerant
Shutoff Valve
[0076] According to what has been described above, one example of
the method of determining the position to place the first shutoff
valve 71a and the second shutoff valve 72a in the refrigerant
circuit 10 will be described. Although not restrictive, to begin
with, the second range is determined, which is a range of
refrigerant concentration in which it is considered to be possible
to inhibit the occurrence of combustion accident caused by a
refrigerant leakage in the air conditioning target space when the
refrigerant leakage occurs from the first part 11a. Next, the first
range, which is a range of refrigerant concentration that can be
detected by the refrigerant leakage sensor 50a, is determined. At
this time, in order to allow the refrigerant leakage sensor 50a to
reliably detect the refrigerant having refrigerant concentration in
the second range, the refrigerant concentration in the first range
is set smaller than the refrigerant concentration in the second
range. Finally, the first shutoff valve 71a and the second shutoff
valve 72a are placed at positions where the refrigerant leaked to
the air conditioning target space is within the second range even
if the refrigerant leakage occurs in the first part 11a. As the
positions where the first shutoff valve 71a and the second shutoff
valve 72a are placed move away from the utilization-side unit 3a,
the volume of the utilization-side first connection flow path 21aa
and the volume of the utilization-side second connection flow path
22aa will increase, and therefore an amount of refrigerant that can
exceed the second range may be contained in the first part 11a.
Therefore, the first shutoff valve 71a and the second shutoff valve
72a are placed based on the volume of the utilization-side
refrigerant flow path 13a, the volume of the utilization-side first
connection flow path 21aa, the volume of the utilization-side
second connection flow path 22aa, and the volume of the air
conditioning target space. In this way, the positions to place the
first shutoff valve 71a and the second shutoff valve 72a in the
refrigerant circuit 10 are determined.
[0077] The method of determining the positions to place the first
shutoff valve 71a and the second shutoff valve 72a in the
refrigerant circuit 10 is not limited to the above method, and the
first range may be determined first. For example, as the
refrigerant leakage sensor 50a, the refrigerant leakage sensor 50a
capable of detecting certain concentration in the first range is
determined. Next, the second range is determined such that the
refrigerant concentration in the second range is larger (higher)
than the refrigerant concentration in the first range. This allows
the refrigerant leakage sensor 50a to detect a refrigerant smaller
(thinner) than the second range. Finally, the first shutoff valve
71a and the second shutoff valve 72a are placed at positions where
the refrigerant leaked to the air conditioning target space is
within the second range even if the refrigerant leakage occurs in
the first part 11a. The upper limit of the second range is a value
smaller than LFL/1.
[0078] (5) Features
[0079] (5-1)
[0080] The air conditioning system 100 of the first aspect includes
the refrigerant circuit 10, the heat exchangers 30a, 30b, and 30c,
the shutoff valve 70, and the refrigerant leakage sensors 50a, 50b,
and 50c. The refrigerant circuit 10 includes the first parts 11a,
11b, and 11c and the second part 12. The heat exchangers 30a, 30b,
and 30c are provided in the first parts 11a, 11b, and 11c,
respectively, and cool or heat the air in the air conditioning
target space by exchanging heat between the refrigerant and the air
in the air conditioning target space. The shutoff valve 70 is
provided in the refrigerant circuit 10 and shuts off communication
between the first parts 11a, 11b, and 11c and the second part 12.
The refrigerant leakage sensors 50a, 50b, and 50c detect the
refrigerant leaked from the first parts 11a, 11b, and 11c,
respectively. The refrigerant leakage sensors 50a, 50b, and 50c
detect that the refrigerant concentration is within the first
range. The shutoff valve 70 is placed such that the refrigerant
concentration in the air conditioning target space is within the
second range, which is a range larger than the first range, when it
is assumed that all the refrigerant present in the first parts 11a,
11b, and 11c has leaked to the air conditioning target space.
[0081] In the air conditioning system 100 of the first aspect, the
shutoff valve 70 is placed at a position where the refrigerant
concentration in the air conditioning target space is within the
second range, for example, even if all the refrigerant present in
the first part 11a leaks to the air conditioning target space. This
inhibits the refrigerant concentration in the air conditioning
target space from exceeding LFL (Lower Flammability Limit).
[0082] Furthermore, in the air conditioning system 100 of the first
aspect, the refrigerant concentration in the second range is larger
than the refrigerant concentration in the first range. Accordingly,
for example, if a refrigerant leakage occurs in the first part 11a,
an amount of refrigerant exceeding the LFL/safety factor in the air
conditioning target space is inhibited from leaking from the first
part 11a before the shutoff valve 70 shuts off the flow between the
first part 11a and the second part 12.
[0083] (5-2)
[0084] The air conditioning system 100 of the second aspect is the
air conditioning system 100 of the first aspect, in which when the
lower limit concentration of refrigerant combustion is LFL (Lower
Flammability Limit) [kg/m.sup.3], the first range is from LFL/X1 to
LFL/X2 and the second range is from LFL/Y1 to LFL/Y2. X1 is larger
than Y1, and X2 is larger than Y2.
[0085] The air conditioning system 100 of the second aspect sets
the first range and the second range such that the refrigerant
concentration is smaller than LFL in the air conditioning target
space. This inhibits the refrigerant concentration in the air
conditioning target space from exceeding LFL.
[0086] Note that X1 being larger than Y1 and X2 being larger than
Y2 mean that, in other words, LFL/Y1 is larger than LFL/X1, and
LFL/Y2 is larger than LFL/X2.
[0087] Note that the first range being from LFL/X1 to LFL/X2 means
that, in other words, if the first range is A,
LFL/X1.ltoreq.A.ltoreq.LFL/X2.
[0088] Note that the second range being from LFL/Y1 to LFL/Y2 means
that, in other words, if the second range is B,
LFL/Y1<B<LFL/Y2.
[0089] (5-3)
[0090] The air conditioning system 100 of the third aspect is the
air conditioning system 100 of the first aspect or the second
aspect, in which the refrigerant circuit 10 includes the
utilization-side refrigerant flow paths 13a, 13b, and 13c, which
are part of the first parts 11a, 11b, and 11c, the heat source-side
refrigerant flow path 14, which is part of the second part 12, and
the first connection flow path 21 and the second connection flow
path 22 connecting the utilization-side refrigerant flow paths 13a,
13b, and 13c to the heat source-side refrigerant flow path 14. The
shutoff valve 70 includes the first shutoff valves 71a, 71b, and
71c provided in the first connection flow path 21 and the second
shutoff valves 72a, 72b, and 72c provided in the second connection
flow path 22. The first connection flow path 21 includes the
utilization-side first connection flow paths 21aa, 2 lab, and 21ac
between the utilization-side refrigerant flow paths 13a, 13b, and
13c and the first shutoff valves 71a, 71b, and 71c, and the heat
source-side first connection flow path 21b between the heat
source-side refrigerant flow path 14 and the first shutoff valves
71a, 71b, and 71c. The second connection flow path 22 includes the
utilization-side second connection flow paths 22aa, 22ab, and 22ac
between the utilization-side refrigerant flow paths 13a, 13b, and
13c and the second shutoff valves 72a, 72b, and 72c, and the heat
source-side second connection flow path 22b between the heat
source-side refrigerant flow path 14 and the second shutoff valves
72a, 72b, and 72c. The first shutoff valves 71a, 71b, and 71c and
the second shutoff valves 72a, 72b, and 72c are placed based on the
volume of the utilization-side refrigerant flow paths 13a, 13b, and
13c, the volume of the utilization-side first connection flow paths
21aa, 21ab, and 21ac, the volume of the utilization-side second
connection flow paths 22aa, 22ab, and 22ac, and the volume of the
air conditioning target space.
[0091] In the air conditioning system 100 of the third aspect, the
first shutoff valves 71a, 71b, and 71c and the second shutoff
valves 72a, 72b, and 72c are placed based on the volume of the
utilization-side refrigerant flow paths 13a, 13b, and 13c, the
volume of the utilization-side first connection flow paths 21aa,
21ab, and 21ac, the volume of the utilization-side second
connection flow paths 22aa, 22ab, and 22ac, and the volume of the
air conditioning target space. This inhibits the refrigerant
concentration in the air conditioning target space from exceeding
LFL.
[0092] (5-4)
[0093] The air conditioning system 100 of the fourth aspect is the
air conditioning system 100 of the first aspect, in which when the
lower limit concentration of refrigerant combustion is LFL
[kg/m.sup.3], the first range is from LFL/X1 to LFL/X2 and the
second range is from LFL/Y1 to LFL/Y2. LFL/Y1 is larger than
LFL/X1, and LFL/Y2 is larger than LFL/X2.
[0094] The air conditioning system 100 of the fourth aspect sets
the first range and the second range such that the refrigerant
concentration is smaller than LFL in the air conditioning target
space. This inhibits the refrigerant concentration in the air
conditioning target space from exceeding LFL.
[0095] Note that the first range being from LFL/X1 to LFL/X2 means
that, in other words, if the first range is A,
LFL/X1.ltoreq.A.ltoreq.LFL/X2.
[0096] The second range being from LFL/Y1 to LFL/Y2 means that, in
other words, if the second range is B, LFL/Y1<B<LFL/Y2.
[0097] (6) Modifications
[0098] The above-described embodiment can be appropriately modified
as shown in the following modifications. Each modification may be
applied in combination with other modifications insofar as no
inconsistency arises. Note that constituent elements similar to
those described in the first embodiment are denoted with similar
reference signs, and the detailed description thereof will be
omitted.
[0099] (6-1) Modification A
[0100] The above-described embodiment has described an example in
which the first shutoff valves 71a, 71b, and 71c and the second
shutoff valves 72a, 72b, and 72c are placed in the refrigerant
circuit 10 so as to correspond to the utilization-side units 3a,
3b, and 3c, respectively. However, if the above-described shutoff
valves are placed at positions where the refrigerant concentration
in the air conditioning target space is within the second range
when it is assumed that all the refrigerant present in a first part
11A at a predetermined temperature, predetermined pressure, and
predetermined phase state has leaked to the air conditioning target
space, as shown in FIG. 4, one first shutoff valve 71A and one
second shutoff valve 72A may be connected to each of the plurality
of utilization-side units 3a, 3b, and 3c.
[0101] In this case, as shown in FIG. 4, the first part 11A
includes the utilization-side refrigerant flow path 13a, the
utilization-side refrigerant flow path 13b, the utilization-side
refrigerant flow path 13c, the utilization-side liquid refrigerant
pipe 37a, the utilization-side liquid refrigerant pipe 37b, the
utilization-side liquid refrigerant pipe 37c, a utilization-side
first connection flow path 21A, and a utilization-side second
connection flow path 22A. The first connection flow path 21
includes the utilization-side first connection flow path 21A and
the heat source-side first connection flow path 21b. The second
connection flow path 22 includes the utilization-side second
connection flow path 22A and the heat source-side second connection
flow path 22b. Note that the configuration of the first shutoff
valve 71A and the second shutoff valve 72A is similar to the
configuration of the first shutoff valves 71a, 71b, and 71c and the
second shutoff valves 72a, 72b, and 72c, and thus the description
thereof will be omitted.
[0102] Note that in FIG. 4, the utilization-side control unit 93a
is connected to the first shutoff valve 71A and the second shutoff
valve 72A, but this is not restrictive. The utilization-side
control unit 93b or the utilization-side control unit 93c may be
connected to the first shutoff valve 71A and the second shutoff
valve 72A.
[0103] FIG. 4 illustrates the utilization-side units 3a, 3b, and
3c, but the number of utilization-side units is not limited to this
example, and may be three or less, or three or more.
[0104] (6-2) Modification B
[0105] The above-described embodiment has described an example in
which the first shutoff valves 71a, 71b, and 71c and the second
shutoff valves 72a, 72b, and 72c are placed corresponding to the
three utilization-side units 3a, 3b, and 3c. However, the number of
utilization-side units is not limited to three, and the number of
first shutoff valves and the second shutoff valves is not limited
to three. For example, as shown in FIG. 5, one utilization-side
unit 3S may be connected to the heat source-side unit 2 by the
first connection flow path 21 and the second connection flow path
22 via one first shutoff valve 71S and one second shutoff valve
72S.
[0106] In this case, as shown in FIG. 5, a first part 11S includes
a utilization-side refrigerant flow path 13S, a utilization-side
liquid refrigerant pipe 37S, a utilization-side first connection
flow path 21S, and a utilization-side second connection flow path
22S. The first connection flow path 21 includes the
utilization-side first connection flow path 21S and the heat
source-side first connection flow path 21b. The second connection
flow path 22 includes the utilization-side second connection flow
path 22S and the heat source-side second connection flow path
22b.
[0107] Note that the configuration of constituent devices 30S, 34S,
36S, 37S, 50S, and 92S of the utilization-side unit 3S is similar
to the configuration of various constituent devices 30a, 30b, 30c,
34a, 34b, 34c, 36a, 36b, 36c, 37a, 37b, 37c, 50a, 50b, 50c, 92a,
92b, and 92c of the utilization-side units 3a, 3b, and 3c, and thus
the description thereof will be omitted. The configuration of the
utilization-side refrigerant flow path 13S is similar to the
configuration of the utilization-side refrigerant flow paths 13a,
13b, and 13c, and thus the description thereof will be omitted.
[0108] (6-3) Modification C
[0109] The above-described embodiment has described that the
utilization-side control units 93a, 93b, and 93c control the first
shutoff valves 71a, 71b, and 71c and the second shutoff valves 72a,
72b, and 72c, respectively. However, the heat source-side control
unit 92 may control the first shutoff valves 71a, 71b, and 71c and
the second shutoff valves 72a, 72b, and 72c.
[0110] (6-4) Modification D
[0111] The above-described embodiment has described that the
control unit 19 is configured by connecting the heat source-side
control unit 92 to the utilization-side control units 93a, 93b, and
93c via the transmission line 90. However, the heat source-side
control unit 92 or the utilization-side control units 93a, 93b, and
93c may control the operation of the entire air conditioning
apparatus 1. For example, the heat source-side control unit 92 may
control various constituent devices 15, 17a, 17b, 23, 24, 25, 26,
30a, 30b, 30c, 34a, 34b, 34c, 36a, 36b, 36c, 71a, 71b, 71c, 72a,
72b, and 72c of the air conditioning apparatus 1 based on detection
signals of various sensors (not shown), the refrigerant leakage
sensors 50a, 50b, and 50c, and the like.
[0112] (6-5) Modification E
[0113] The above-described embodiment has described an example in
which the first shutoff valves 71a, 71b, and 71c and the second
shutoff valves 72a, 72b, and 72c are placed outside the
utilization-side units 3a, 3b, and 3c and the heat source-side unit
2. However, as shown in FIG. 6, the utilization-side unit 3a may
include the first shutoff valves 71a, 71b, and 71c and the second
shutoff valves 72a, 72b, and 72c inside the utilization-side units
3a, 3b, and 3c, by placement inside the casing of the
utilization-side units 3a, 3b, and 3c. The first shutoff valves
71a, 71b, and 71c and the second shutoff valves 72a, 72b, and 72c
placed inside the casing may be controlled by, for example, the
utilization-side control units 93a, 93b, and 93c, although not
restrictive.
[0114] <Supplementary Note>
[0115] The embodiment of the present disclosure has been described
above. It will be understood that various changes to modes and
details can be made without departing from the spirit and scope of
the present disclosure recited in the claims.
REFERENCE SIGNS LIST
[0116] 10: refrigerant circuit [0117] 11a, 11b, 11c, 11A, 11S:
first part [0118] 12: second part [0119] 13a, 13b, 13c, 13S:
utilization-side refrigerant flow path [0120] 14: heat source-side
refrigerant flow path [0121] 21: first connection flow path [0122]
22: second connection flow path [0123] 21aa, 21ab, 21ac, 21A, 21S:
utilization-side first connection flow path [0124] 21b: heat
source-side first connection flow path [0125] 22aa, 22ab, 22ac,
21A, 21S: utilization-side second connection flow path [0126] 22b:
heat source-side second connection flow path [0127] 30a, 30b, 30c,
30S: heat exchanger [0128] 50a, 50b, 50c, 50S: refrigerant leakage
sensor [0129] 70: shutoff valve (first shutoff valve, second
shutoff valve) [0130] 71a, 71b, 71c, 71A, 71S: first shutoff valve
[0131] 72a, 72b, 72c, 72A, 72S: second shutoff valve [0132] 100:
air conditioning system
CITATION LIST
Patent Literature
[0132] [0133] Patent Literature 1: Japanese Laid-Open Patent
Publication No. 2019-45129
* * * * *