U.S. patent application number 15/766411 was filed with the patent office on 2018-10-11 for refrigeration cycle apparatus and refrigerant leakage detection method.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Mitsuru KAWASHIMA, Takao KOMAI, Akira MAEDA, Yasuhiro SUZUKI, Masahiko TAKAGI, Kenyu TANAKA, Kazuki WATANABE.
Application Number | 20180292118 15/766411 |
Document ID | / |
Family ID | 58695015 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180292118 |
Kind Code |
A1 |
SUZUKI; Yasuhiro ; et
al. |
October 11, 2018 |
REFRIGERATION CYCLE APPARATUS AND REFRIGERANT LEAKAGE DETECTION
METHOD
Abstract
A refrigeration cycle apparatus includes a refrigerant circuit
in which refrigerant circulates, a temperature sensor provided at a
position on the refrigerant circuit, the position being adjacent to
a brazed portion or adjacent to a joint portion in which
refrigerant pipes are joined to each other, and a controller
configured to determine whether or not the refrigerant has leaked
based on a detected temperature detected by the temperature sensor.
The temperature sensor is covered with a heat insulating material
together with the brazed portion or the joint portion.
Inventors: |
SUZUKI; Yasuhiro; (Tokyo,
JP) ; KOMAI; Takao; (Tokyo, JP) ; MAEDA;
Akira; (Tokyo, JP) ; KAWASHIMA; Mitsuru;
(Tokyo, JP) ; TAKAGI; Masahiko; (Tokyo, JP)
; TANAKA; Kenyu; (Tokyo, JP) ; WATANABE;
Kazuki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
58695015 |
Appl. No.: |
15/766411 |
Filed: |
October 17, 2016 |
PCT Filed: |
October 17, 2016 |
PCT NO: |
PCT/JP2016/080641 |
371 Date: |
April 6, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 2500/222 20130101;
F25B 49/005 20130101; F25B 49/02 20130101 |
International
Class: |
F25B 49/02 20060101
F25B049/02; F25B 49/00 20060101 F25B049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 2015 |
JP |
PCT/JP2015/081514 |
Claims
1. A refrigeration cycle apparatus, comprising: a refrigerant
circuit in which refrigerant circulates; a temperature sensor
provided at a position on the refrigerant circuit, the position
being adjacent to a brazed portion or the position being adjacent
to a joint portion in which refrigerant pipes are joined to each
other; and a controller configured to determine whether or not the
refrigerant has leaked based on a detected temperature detected by
the temperature sensor, wherein the temperature sensor is covered
with a heat insulating material together with the brazed portion or
the joint portion.
2. The refrigeration cycle apparatus of claim 1, wherein the
controller is configured to determine that the refrigerant has
leaked when the detected temperature is lower than a threshold
temperature.
3. The refrigeration cycle apparatus of claim 1, wherein the
controller is configured to determine that the refrigerant has
leaked when a temporal change of the detected temperature is lower
than a threshold value.
4. The refrigeration cycle apparatus of claim 1, further comprising
a fan, wherein the controller is configured to determine whether or
not the refrigerant has leaked only when the fan is stopped.
5. The refrigeration cycle apparatus of claim 1, wherein the
temperature sensor is provided below the brazed portion or the
joint portion.
6. The refrigeration cycle apparatus of claim 1, wherein the
temperature sensor is provided above or beside the brazed portion
or the joint portion.
7. The refrigeration cycle apparatus of claim 1, wherein the
temperature sensor is covered with a heat insulating material that
is same as the heat insulating material covering the brazed portion
or the joint portion.
8. The refrigeration cycle apparatus of claim 1, wherein the heat
insulating material comprises a plurality of heat insulating
members.
9. The refrigeration cycle apparatus of claim 8, wherein, among the
plurality of the heat insulating members, two heat insulating
members that are adjacent to each other are arranged such that end
portions of the two heat insulating members overlap with each
other.
10. The refrigeration cycle apparatus of claim 8, wherein, among
the plurality of the heat insulating members, two heat insulating
members that are adjacent to each other are arranged such that end
surfaces of the two heat insulating members are in contact with
each other.
11. The refrigeration cycle apparatus of claim 8, wherein the
brazed portion or the joint portion is covered with a first heat
insulating member among the plurality of the heat insulating
members, and wherein the temperature sensor is covered with a
second heat insulating member among the plurality of the heat
insulating members.
12. The refrigeration cycle apparatus of claim 1, wherein the
temperature sensor also serves as a temperature sensor configured
to detect a refrigerant temperature of a heat exchanger.
13. A refrigerant leakage detection method, comprising: detecting a
temperature of a position on a refrigerant circuit in which
refrigerant circulates, the position being adjacent to a brazed
portion and being covered with a heat insulating material together
with the brazed portion, or the position being adjacent to a joint
portion in which refrigerant pipes are joined to each other and
being covered with a heat insulating material together with the
joint portion; and determining whether or not the refrigerant has
leaked based on the temperature.
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigeration cycle
apparatus and a refrigerant leakage detection method.
BACKGROUND ART
[0002] In Patent Literature 1, there is described an
air-conditioning apparatus. The air-conditioning apparatus includes
a gas sensor provided on an outer surface of an indoor unit to
detect refrigerant, and a controller configured to perform control
to rotate an indoor fan when the gas sensor detects refrigerant. In
the air-conditioning apparatus, when refrigerant has leaked from an
extension pipe, which is connected to the indoor unit, to the
indoor space, or when refrigerant that has leaked inside the indoor
unit flows to the outside of the indoor unit through a gap of a
casing of the indoor unit, the leaking refrigerant can be detected
by the gas sensor. Further, when a leakage of refrigerant is
detected, by rotating the indoor fan, the indoor air is sucked from
an air inlet formed in the casing of the indoor unit, and the air
is blown off from an air outlet to the indoor space. Therefore, the
leaking refrigerant can be diffused.
[0003] In Patent Literature 2, there is described a refrigeration
apparatus. The refrigeration apparatus includes a temperature
sensor configured to detect a temperature of liquid refrigerant,
and a refrigerant leakage determination unit configured to
determine that refrigerant has leaked when a refrigerant
temperature, which is detected by the temperature sensor when a
compressor is stopped, drops at a rate exceeding a predetermined
rate. The temperature sensor is arranged at a position where liquid
refrigerant may be accumulated in a refrigerant circuit.
Specifically, the temperature sensor is arranged below a header of
an indoor heat exchanger. In Patent Literature 2, it is described
that a rapid leakage of refrigerant can be detected reliably by
detecting a rapid drop of the temperature of the liquid
refrigerant.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Patent No. 4599699
[0005] Patent Literature 2: Japanese Patent No. 3610812
SUMMARY OF INVENTION
Technical Problem
[0006] In the air-conditioning apparatus described in Patent
Literature 1, a gas sensor is used as a refrigerant detection unit.
However, the detection characteristic of a gas sensor is liable to
be aged, and hence there is a problem in that the air-conditioning
apparatus disclosed in Patent Literature 1 may not be capable of
detecting a leakage of refrigerant reliably for a long period of
time.
[0007] Meanwhile, in the refrigeration apparatus described in
Patent Literature 2, instead of a gas sensor, a temperature sensor
having long-term reliability is used as a refrigerant detection
unit. However, when the compressor is stopped, refrigerant
distribution in the refrigerant circuit is not always controllable.
Accordingly, variation arises in the amount of liquid refrigerant
accumulated in a portion in which a temperature sensor is arranged,
and hence variation also arises in the degree of drop of a
refrigerant temperature due to the heat of vaporization when
refrigerant leaks. Further, a leakage of refrigerant does not
always occur at a place where liquid refrigerant is accumulated.
When refrigerant leaks at a place other than the place where liquid
refrigerant is accumulated, gas refrigerant is mainly leaked first.
Accordingly, it takes time until liquid refrigerant is gasified at
a place where the liquid refrigerant is accumulated and the
refrigerant temperature drops. Therefore, in the refrigeration
apparatus described in Patent Literature 2, there is a problem in
that a leakage of refrigerant may not be detected with high
responsiveness.
[0008] The present invention has been made to solve the
above-mentioned problems, and it is an object of the present
invention to provide a refrigeration cycle apparatus and a
refrigerant leakage detection method, which are capable of
detecting a leakage of refrigerant reliably with high
responsiveness for a long period of time.
Solution to Problem
[0009] A refrigeration cycle apparatus according to one embodiment
of the present invention includes: a refrigerant circuit in which
refrigerant circulates; a temperature sensor provided at a position
on the refrigerant circuit, the position being adjacent to a brazed
portion or the position being adjacent to a joint portion in which
refrigerant pipes are joined to each other; and a controller
configured to determine whether or not the refrigerant has leaked
based on a detected temperature detected by the temperature sensor.
The temperature sensor is covered with a heat insulating material
together with the brazed portion or the joint portion.
[0010] Further, a refrigerant leakage detection method according to
one embodiment of the present invention includes: detecting a
temperature of a position on a refrigerant circuit in which
refrigerant circulates, the position being adjacent to a brazed
portion and being covered with a heat insulating material together
with the brazed portion, or the position being adjacent to a joint
portion in which refrigerant pipes are joined and being covered
with a heat insulating material together with the joint portion;
and determining whether or not the refrigerant has leaked based on
the temperature.
Advantageous Effects of Invention
[0011] According to one embodiment of the present invention, a
leakage of refrigerant can be detected reliably with high
responsiveness for a long period of time.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a refrigerant circuit diagram for illustrating a
schematic configuration of an air-conditioning apparatus according
to Embodiment 1 of the present invention.
[0013] FIG. 2 is a front view for illustrating an external
appearance configuration of an indoor unit 1 of the
air-conditioning apparatus according to Embodiment 1 of the present
invention.
[0014] FIG. 3 is a front view for schematically illustrating an
internal structure of the indoor unit 1 of the air-conditioning
apparatus according to Embodiment 1 of the present invention.
[0015] FIG. 4 is a side view for schematically illustrating the
internal structure of the indoor unit 1 of the air-conditioning
apparatus according to Embodiment 1 of the present invention.
[0016] FIG. 5 is a front view for schematically illustrating a
configuration of a load-side heat exchanger 7 and the peripheral
components thereof of the air-conditioning apparatus according to
Embodiment 1 of the present invention.
[0017] FIG. 6 is a schematic diagram for illustrating a
modification example of a configuration of a heat insulating
material 82d illustrated in FIG. 5.
[0018] FIG. 7 is a schematic diagram for illustrating another
modification example of the configuration of the heat insulating
material 82d illustrated in FIG. 5.
[0019] FIG. 8 is a graph for showing exemplary temporal changes of
the temperature detected by a temperature sensor 94a when
refrigerant is caused to leak from a joint 15b in the indoor unit 1
of the air-conditioning apparatus according to Embodiment 1 of the
present invention.
[0020] FIG. 9 is a flowchart for illustrating an example of
refrigerant leakage detection processing to be performed by a
controller 30 of the air-conditioning apparatus according to
Embodiment 1 of the present invention.
[0021] FIG. 10 is a flowchart for illustrating another example of
refrigerant leakage detection processing to be performed by the
controller 30 of the air-conditioning apparatus according to
Embodiment 1 of the present invention.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0022] A refrigeration cycle apparatus and a refrigerant leakage
detection method according to Embodiment 1 of the present invention
are described. In Embodiment 1, an air-conditioning apparatus is
described as an example of a refrigeration cycle apparatus. FIG. 1
is a refrigerant circuit diagram for illustrating a schematic
configuration of the air-conditioning apparatus according to
Embodiment 1. In the drawings described below including FIG. 1, the
dimensional relationships and the shapes of the respective
constituent members may be different from actual ones.
[0023] As illustrated in FIG. 1, the air-conditioning apparatus
includes a refrigerant circuit 40 in which refrigerant circulates.
The refrigerant circuit 40 has a configuration in which a
compressor 3, a refrigerant flow path switching device 4, a heat
source-side heat exchanger 5 (for example, outdoor heat exchanger),
a decompression device 6, and a load-side heat exchanger 7 (for
example, indoor heat exchanger) are sequentially connected via
refrigerant pipes to form a ring. The air-conditioning apparatus
also includes as a heat source unit an outdoor unit 2, which is
installed outside the indoor space, for example. Further, the
air-conditioning apparatus also includes as a load unit an indoor
unit 1, which is installed in the indoor space, for example. The
indoor unit 1 and the outdoor unit 2 are connected to each other
via extension pipes 10a and 10b, which are part of the refrigerant
pipes.
[0024] As refrigerant circulating in the refrigerant circuit 40,
slightly flammable refrigerant such as HFO-1234yf or HFO-1234ze, or
highly flammable refrigerant such as R290 or R1270 may be used, for
example. Such refrigerant may be used as single refrigerant, or as
mixed refrigerant in which two or more types of refrigerant are
mixed. Refrigerant having a slightly flammable level or higher (for
example, 2 L or higher in the classification of ASHRAE34) may be
hereinafter referred to as "flammable refrigerant". Further, as
refrigerant circulating in the refrigerant circuit 40, it is also
possible to use nonflammable refrigerant such as R22 or R410A
having no flammability (for example, 1 in the classification of
ASHRAE34). Those types of refrigerant have density larger than that
of air under the atmospheric pressure, for example.
[0025] The compressor 3 is fluid machinery configured to compress
sucked low-pressure refrigerant and discharge the resultant
refrigerant as high-pressure refrigerant. The refrigerant flow path
switching device 4 is configured to switch a flow direction of the
refrigerant in the refrigerant circuit 40 between the cooling
operation and the heating operation. As the refrigerant flow path
switching device 4, a four-way valve is used, for example. The heat
source-side heat exchanger 5 is a heat exchanger that functions as
a radiator (for example, condenser) at the time of cooling
operation, and functions as an evaporator at the time of heating
operation. In the heat source-side heat exchanger 5, heat exchange
is performed between the refrigerant flowing inside and the outdoor
air supplied by an outdoor fan 5f described later. The
decompression device 6 is configured to decompress high-pressure
refrigerant into low-pressure refrigerant. As the decompression
device 6, an electronic expansion valve, in which the opening
degree is adjustable, or similar valve may be used, for example.
The load-side heat exchanger 7 is a heat exchanger that functions
as an evaporator at the time of cooling operation, and functions as
a radiator (for example, condenser) at the time of heating
operation. In the load-side heat exchanger 7, heat exchange is
performed between the refrigerant flowing inside and the air
supplied by an indoor fan 7f described later. The cooling operation
refers to an operation of supplying low-temperature and
low-pressure refrigerant to the load-side heat exchanger 7, and the
heating operation refers to an operation of supplying
high-temperature and high-pressure refrigerant to the load-side
heat exchanger 7.
[0026] In the outdoor unit 2, the compressor 3, the refrigerant
flow path switching device 4, the heat source-side heat exchanger
5, and the decompression device 6 are accommodated. The outdoor fan
5f configured to supply outdoor air to the heat source-side heat
exchanger 5 is also accommodated in the outdoor unit 2. The outdoor
fan 5f is arranged to face the heat source-side heat exchanger 5.
When the outdoor fan 5f is rotated, an air flow passing through the
heat source-side heat exchanger 5 is generated. As the outdoor fan
5f, a propeller fan is used, for example. The outdoor fan 5f is
arranged downstream of the heat source-side heat exchanger 5, for
example, in the air flow generated by the outdoor fan 5f.
[0027] In the outdoor unit 2, as refrigerant pipes, there are
arranged a refrigerant pipe connecting an extension pipe connection
valve 13a that is on the gas side at the time of cooling operation
and the refrigerant flow path switching device 4, a suction pipe 11
connected to the suction side of the compressor 3, a discharge pipe
12 connected to the discharge side of the compressor 3, a
refrigerant pipe connecting the refrigerant flow path switching
device 4 and the heat source-side heat exchanger 5, a refrigerant
pipe connecting the heat source-side heat exchanger 5 and the
decompression device 6, and a refrigerant pipe connecting an
extension pipe connection valve 13b that is on the liquid side at
the time of cooling operation and the decompression device 6. The
extension pipe connection valve 13a is a two-way valve that can be
switched to be opened or closed, and one end thereof has a joint
16a (for example, flare joint) mounted thereto. Further, the
extension pipe connection valve 13b is constructed of a three-way
valve that can be switched to be opened or closed. One end of the
extension pipe connection valve 13b has mounted thereto a service
port 14a to be used for vacuum drawing that is a prior work of
filling the refrigerant circuit 40 with refrigerant, and the other
end thereof has a joint 16b (for example, flare joint) mounted
thereto.
[0028] In the discharge pipe 12, high-temperature and high-pressure
gas refrigerant compressed by the compressor 3 flows both at the
time of cooling operation and at the time of heating operation. In
the suction pipe 11, low-temperature and low-pressure gas
refrigerant after evaporation or two phase refrigerant flows both
at the time of cooling operation and at the time of heating
operation. The suction pipe 11 is connected to a service port 14b
with a flare joint of the low-pressure side, and the discharge pipe
12 is connected to a service port 14c with a flare joint of the
high-pressure side. The service ports 14b and 14c are used for
measuring the operation pressure with a pressure gauge connected
thereto, when a trial operation is performed at the time of
installing or repairing the air-conditioning apparatus.
[0029] The indoor unit 1 accommodates the load-side heat exchanger
7. The indoor unit 1 also accommodates the indoor fan 7f configured
to supply air to the load-side heat exchanger 7. When the indoor
fan 7f is rotated, an air flow passing through the load-side heat
exchanger 7 is generated. As the indoor fan 7f, a centrifugal fan
(for example, sirocco fan or turbo fan), a cross flow fan, a mixed
flow fan, an axial fan (for example, propeller fan), or other fan
may be used depending on the form of the indoor unit 1. While the
indoor fan 7f of Embodiment 1 is arranged upstream of the load-side
heat exchanger 7 in the air flow generated by the indoor fan 7f,
the indoor fan 7f may be arranged downstream of the load-side heat
exchanger 7.
[0030] In an indoor pipe 9a on the gas side among the refrigerant
pipes of the indoor unit 1, a connecting portion to the extension
pipe 10a of the gas side has mounted thereto a joint 15a (for
example, flare joint) for connecting the extension pipe 10a to the
connecting portion. Further, in an indoor pipe 9b on the liquid
side of the refrigerant pipes of the indoor unit 1, a connecting
portion to the extension pipe 10b on the liquid side has mounted
thereto a joint 15b (for example, flare joint) for connecting the
extension pipe 10b to the connecting portion.
[0031] The indoor unit 1 also includes an intake air temperature
sensor 91 configured to detect a temperature of the indoor air
sucked from the indoor space, a heat exchanger liquid pipe
temperature sensor 92 configured to detect a temperature of liquid
refrigerant at an inlet port at the time of cooling operation
(outlet port at the time of heating operation) of the load-side
heat exchanger 7, a heat exchanger two-phase pipe temperature
sensor 93 configured to detect a temperature of the two-phase
refrigerant (evaporating temperature or condensing temperature) of
the load-side heat exchanger 7, and other sensors. The indoor unit
1 also includes temperature sensors 94a, 94b, 94c, and 94d (not
shown in FIG. 1) for detecting a refrigerant leakage described
below. Those temperature sensors 91, 92, 93, 94a, 94b, 94c, and 94d
output detection signals to the controller 30 configured to control
the indoor unit 1 or the entire air-conditioning apparatus.
[0032] The controller 30 includes a microcomputer including a CPU,
a ROM, a RAM, an I/O port, a timer, and other components. The
controller 30 is configured to perform data communication to/from
an operation unit 26 (see FIG. 2). The operation unit 26 receives
an operation by a user and output an operation signal, which is
based on the operation, to the controller 30. The controller 30 of
Embodiment 1 controls an operation of the indoor unit 1 or the
entire air-conditioning apparatus including an operation of the
indoor fan 7f based on the operation signal from the operation unit
26, detection signals from the sensors, and other signals. The
controller 30 may be provided in the casing of the indoor unit 1 or
in the casing of the outdoor unit 2. Further, the controller 30 may
be constructed of an outdoor unit control unit provided in the
outdoor unit 2, and an indoor unit control unit provided in the
indoor unit 1 and capable of performing data communication to/from
the outdoor unit control unit.
[0033] Next, an operation of the refrigerant circuit 40 of the
air-conditioning apparatus is described. First, an operation at the
time of cooling operation is described. In FIG. 1, the arrow of the
solid line indicates a flow direction of refrigerant at the time of
cooling operation. In the cooling operation, the refrigerant flow
path is switched to that indicated by the solid line by the
refrigerant flow path switching device 4, and the refrigerant
circuit 40 is configured such that low-temperature and low-pressure
refrigerant flows to the load-side heat exchanger 7.
[0034] The high-temperature and high-pressure gas refrigerant
discharged from the compressor 3 first flows into the heat
source-side heat exchanger 5 via the refrigerant flow path
switching device 4. In the cooling operation, the heat source-side
heat exchanger 5 functions as a condenser. Specifically, in the
heat source-side heat exchanger 5, heat exchange is performed
between the refrigerant flowing inside and the outdoor air supplied
by the outdoor fan 5f, and the heat of condensation of the
refrigerant is radiated to the outdoor air. In this way, the
refrigerant flowing into the heat source-side heat exchanger 5 is
condensed to be high-pressure liquid refrigerant. The high-pressure
liquid refrigerant flows into the decompression device 6, and is
decompressed to be low-pressure two-phase refrigerant. The
low-pressure two-phase refrigerant flows into the load-side heat
exchanger 7 of the indoor unit 1 via the extension pipe 10b. In the
cooling operation, the load-side heat exchanger 7 functions as an
evaporator. Specifically, in the load-side heat exchanger 7, heat
exchange is performed between the refrigerant flowing inside and
the air supplied by the indoor fan 7f (for example, indoor air),
and the heat of evaporation of the refrigerant is removed from the
air. In this way, the refrigerant flowing into the load-side heat
exchanger 7 evaporates to be low-pressure gas refrigerant or
two-phase refrigerant. Further, the air supplied by the indoor fan
7f is cooled by heat removal action of the refrigerant. The
low-pressure gas refrigerant or the two-phase refrigerant
evaporated in the load-side heat exchanger 7 is sucked by the
compressor 3 via the extension pipe 10a and the refrigerant flow
path switching device 4. The refrigerant sucked by the compressor 3
is compressed to be high-temperature and high-pressure gas
refrigerant. In the cooling operation, the cycle described above is
repeated.
[0035] Next, an operation at the time of heating operation is
described. In FIG. 1, the arrow of the dotted line indicates a flow
direction of refrigerant at the time of heating operation. In the
heating operation, a refrigerant flow path is switched to that
indicated by the dotted line by the refrigerant flow path switching
device 4, and the refrigerant circuit 40 is configured such that
high-temperature and high-pressure refrigerant flows to the
load-side heat exchanger 7. In the heating operation, the
refrigerant flows in a direction opposite to that in the cooling
operation, and the load-side heat exchanger 7 functions as a
condenser. Specifically, in the load-side heat exchanger 7, heat
exchange is performed between the refrigerant flowing inside and
the air supplied by the indoor fan 7f, and the heat of condensation
of the refrigerant is radiated to the air. In this way, the air
supplied by the indoor fan 7f is heated by the heat radiation
action of the refrigerant.
[0036] FIG. 2 is a front view for illustrating an external
appearance configuration of the indoor unit 1 of the
air-conditioning apparatus according to Embodiment 1. FIG. 3 is a
front view for schematically illustrating an internal structure of
the indoor unit 1. FIG. 4 is a side view for schematically
illustrating the internal structure of the indoor unit 1. The left
side of FIG. 4 is a front side (indoor space side) of the indoor
unit 1. In Embodiment 1, as the indoor unit 1, the indoor unit 1 of
the floor type, which is to be installed on the floor of an indoor
space that is an air-conditioned space, is illustrated exemplarily.
The positional relation (for example, up and down relation) between
the respective constituent members in the following description is
that when the indoor unit 1 is installed in a usable state, in
principle.
[0037] As illustrated in FIG. 2 to FIG. 4, the indoor unit 1
includes a casing 111 having a vertically long rectangular
parallelepiped shape. A lower portion of the front surface of the
casing 111 has formed therein an air inlet 112 for sucking the air
of the indoor space. The air inlet 112 of Embodiment 1 is provided
at a position below a center portion in the vertical direction of
the casing 111 and in the vicinity of the floor. An upper portion
of the front surface of the casing 111, that is, a position higher
than the height of the air inlet 112 (for example, above the center
portion in the vertical direction of the casing 111), has formed
therein an air outlet 113 for blowing off the air sucked from the
air inlet 112 to the indoor space. On the front surface of the
casing 111, the operation unit 26 is provided above the air inlet
112 and below the air outlet 113. The operation unit 26 is
connected to the controller 30 via a communication line, and is
capable of performing data communication to/from the controller 30.
In the operation unit 26, a start operation and a stop operation of
the air-conditioning apparatus, switching of operation mode,
setting of set temperature and set air flow amount, and other
operations are performed by a user's operation. In the operation
unit 26, a display unit, a sound output unit, and other units are
provided as informing units configured to inform the user of
information.
[0038] The casing 111 is a hallow box. The front surface of the
casing 111 has formed therein a front open part. The casing 111
includes a first front panel 114a, a second front panel 114b, and a
third front panel 114c that are mounted attachably/detachably to
the front open part. Each of the first front panel 114a, the second
front panel 114b, and the third front panel 114c has a
substantially rectangular flat plate outer shape. The first front
panel 114a is mounted attachably/detachably to the lower portion of
the front open part of the casing 111. In the first front panel
114a, the air inlet 112 is formed. The second front panel 114b is
arranged adjacently above the first front panel 114a, and is
mounted attachably/detachably to the center portion in the vertical
direction of the front open part of the casing 111. On the second
front panel 114b, the operation unit 26 is provided. The third
front panel 114c is arranged adjacently above the second front
panel 114b, and is mounted attachably/detachably with respect to
the upper portion of the front open part of the casing 111. In the
third front panel 114c, the air outlet 113 is formed.
[0039] The internal space of the casing 111 is roughly divided into
a lower space 115a serving as an air sending unit, and an upper
space 115b located above the lower space 115a and serving as a heat
exchange unit. The lower space 115a and the upper space 115b are
partitioned by a partition 20. The partition 20 has a flat plate
shape, for example, and is arranged almost horizontally. The
partition 20 at least includes an air passage opening port 20a
serving as an air passage between the lower space 115a and the
upper space 115b. The lower space 115a is exposed to the front
surface side when the first front panel 114a is removed from the
casing 111. The upper space 115b is exposed to the front surface
side when the second front panel 114b and the third front panel
114c are removed from the casing 111. That is, the height where the
partition 20 is arranged almost matches the height of the top end
of the first front panel 114a or the bottom end of the second front
panel 114b. The partition 20 may be integrally formed with a fan
casing 108 described later, may be integrally formed with a drain
pan described later, or may be formed separately of the fan casing
108 and the drain pan.
[0040] In the lower space 115a, the indoor fan 7f is arranged. The
indoor fan 7f generates an air flow from the air inlet 112 to the
air outlet 113 in an air passage 81 in the casing 111. The indoor
fan 7f of Embodiment 1 is a sirocco fan including a motor (not
shown), and an impeller 107 that is connected to the output shaft
of the motor and in which a plurality of vanes are
circumferentially arranged with equal intervals, for example. The
rotating shaft of the impeller 107 is arranged to be in almost
parallel with the depth direction of the casing 111. As the motor
of the indoor fan 7f, a non-brush type motor (for example,
induction motor or DC brushless motor) is used. Accordingly, no
sparking is caused when the indoor fan 7f rotates.
[0041] The impeller 107 of the indoor fan 7f is covered with the
spiral shaped fan casing 108. The fan casing 108 is formed
separately of the casing 111, for example. Near the center of the
spiral of the fan casing 108, a suction opening port 108b for
sucking the indoor air into the fan casing 108 via the air inlet
112 is formed. The suction opening port 108b is arranged to face
the air inlet 112. Further, in the tangential direction of the
spiral of the fan casing 108, an air outlet opening port 108a from
which sending air is blown off is formed. The air outlet opening
port 108a is arranged to face upward and is connected to the upper
space 115b via the air passage opening port 20a of the partition
20. In other words, the air outlet opening port 108a communicates
to the upper space 115b via the air passage opening port 20a. An
opening end of the air outlet opening port 108a and an opening end
of the air passage opening port 20a may be connected directly to
each other, or may be connected indirectly to each other via a duct
member, for example.
[0042] Further, the lower space 115a has an electrical component
box 25 in which a microcomputer constructing the controller 30,
various electrical components, a substrate, and other components
are stored, for example.
[0043] The upper space 115b is located downstream of the lower
space 115a in the flow of air caused by the indoor fan 7f. On the
air passage 81 in the upper space 115b, the load-side heat
exchanger 7 is arranged. Below the load-side heat exchanger 7, a
drain pan (not shown) for receiving condensed water condensed on
the surface of the load-side heat exchanger 7 is provided. The
drain pan may be formed as a part of the partition 20, or may be
formed separately of the partition 20 and arranged on the partition
20.
[0044] When the indoor fan 7f is driven, the indoor air is sucked
from the air inlet 112. The sucked indoor air passes through the
load-side heat exchanger 7 to be conditioned air, and is blown off
from the air outlet 113 to the indoor space.
[0045] FIG. 5 is a front view for schematically illustrating the
configuration of the load-side heat exchanger 7 and the peripheral
components thereof of the air-conditioning apparatus according to
Embodiment 1. As illustrated in FIG. 5, the load-side heat
exchanger 7 of Embodiment 1 is a plate fin tube type heat exchanger
including a plurality of fins 70 arranged in parallel with
predetermined intervals, and a plurality of heat transfer tubes 71
penetrating the plurality of fins 70 and allowing the refrigerant
to flow through the inside thereof. The heat transfer tube 71 is
constructed of a plurality of hair-pin pipes 72 having long
straight pipes penetrating the plurality of fins 70 and a plurality
of U bent pipes 73 allowing the adjacent hair-pin pipes 72 to
communicate to each other. The hair-pin pipe 72 and the U bent pipe
73 are joined by a brazed portion W. In FIG. 5, the brazed portion
W is indicated by a black dot. The number of heat transfer tubes 71
may be one or plural. Further, the number of hair-pin pipes 72
constructing one heat transfer tube 71 may be one or plural. The
heat exchanger two-phase pipe temperature sensor 93 is provided on
the U bent pipe 73 located in the middle of the refrigerant channel
in the heat transfer tube 71.
[0046] The indoor pipe 9a of the gas side is connected to a
cylindrical header main pipe 61. To the header main pipe 61, a
plurality of header branch pipes 62 are connected in a branched
manner. Each of the header branch pipes 62 is connected to one end
portion 71a of the heat transfer tube 71. To the indoor pipe 9b of
the liquid side, a plurality of indoor refrigerant branch pipes 63
are connected in a branched manner. Each of the indoor refrigerant
branch pipes 63 is connected to an other end portion 71b of the
heat transfer tube 71. The heat exchanger liquid pipe temperature
sensor 92 is provided on the indoor pipe 9b.
[0047] The indoor pipe 9a and the header main pipe 61, the header
main pipe 61 and the header branch pipe 62, the header branch pipe
62 and the heat transfer tube 71, the indoor pipe 9b and the indoor
refrigerant branch pipe 63, and the indoor refrigerant branch pipe
63 and the heat transfer tube 71 are each joined by the brazed
portions W.
[0048] In Embodiment 1, the brazed portions W of the load-side heat
exchanger 7 (in Embodiment 1, including the brazed portions W of
the peripheral components of the indoor pipe 9a, the header main
pipe 61, the header branch pipe 62, the indoor refrigerant branch
pipe 63, the indoor pipe 9b, and other pipes) are arranged in the
upper space 115b. The indoor pipes 9a and 9b penetrate the
partition 20 and are drawn downward from the upper space 115b to
the lower space 115a. The joint 15a connecting the indoor pipe 9a
and the extension pipe 10a and the joint 15b connecting the indoor
pipe 9b and the extension pipe 10b are arranged in the lower space
115a.
[0049] To the indoor pipes 9a and 9b in the upper space 115b, the
temperature sensors 94c and 94d for detecting a refrigerant leakage
are provided separately from the heat exchanger liquid pipe
temperature sensor 92 and the heat exchanger two-phase pipe
temperature sensor 93, which are used for operation control of the
refrigerant circuit 40. The temperature sensor 94c is provided at a
position adjacent to the brazed portion W of the load-side heat
exchanger 7 of the indoor pipe 9a to be in contact with the outer
peripheral surface of the indoor pipe 9a. The temperature sensor
94c is provided below the lowermost brazed portion W and in the
vicinity of the same brazed portion W, for example. The temperature
sensor 94d is provided at a position adjacent to the brazed portion
W of the load-side heat exchanger 7 of the indoor pipe 9b to be in
contact with the outer peripheral surface of the indoor pipe 9b.
The temperature sensor 94d is provided below the lowermost brazed
portion W among at least the brazed portions W of the indoor pipe
9b in the vicinity of the same brazed portion W.
[0050] Below the indoor pipe 9a, the header main pipe 61, the
header branch pipe 62, the indoor refrigerant branch pipe 63, and
the indoor pipe 9b, the partition 20, that is, a drain pan, is
provided. Accordingly, in the upper space 115b, there is originally
no particular need to provide a heat insulating material around the
indoor pipe 9a, the header main pipe 61, the header branch pipe 62,
the indoor refrigerant branch pipe 63, and the indoor pipe 9b.
However, in Embodiment 1, the indoor pipe 9a, the header main pipe
61, the header branch pipe 62, the indoor refrigerant branch pipe
63, and the indoor pipe 9b (at least the brazed portions W where
those pipes are joined) located above (for example, immediately
above) the drain pan are integrally covered with a unit of heat
insulating material 82d (for example, one heat insulating member or
a pair of insulating members closely attached to each other via
mating surfaces). As described later with use of FIG. 6 and FIG. 7,
the heat insulating material 82d may be constructed of a plurality
of heat insulating members connected integrally. The heat
insulating material 82d is closely attached to the refrigerant
pipes, and hence only a minute gap is formed between the outer
peripheral surface of each refrigerant pipe and the heat insulating
material 82d, The heat insulating material 82d is mounted in the
manufacturing step of the indoor unit 1 by an air-conditioning
apparatus manufacturer.
[0051] The temperature sensors 94c and 94d are covered with the
heat insulating material 82d, together with the brazed portions W
of the load-side heat exchanger 7, the indoor pipes 9a and 9b, and
other pipes. Specifically, the temperature sensor 94c is provided
on the internal side of the heat insulating material 82d, and
detects a temperature of the portion covered with the heat
insulating material 82d in the indoor pipe 9a. The temperature
sensor 94d is provided on the internal side of the heat insulating
material 82d, and detects a temperature of the portion covered with
the heat insulating material 82d in the indoor pipe 9b. Further, in
Embodiment 1, the heat exchanger liquid pipe temperature sensor 92
and the heat exchanger two-phase pipe temperature sensor 93 are
also covered with the heat insulating material 82d.
[0052] The indoor pipes 9a and 9b in the lower space 115a are
covered with a heat insulating material 82b for preventing dew
condensation, except for the portions near the joints 15a and 15b.
In Embodiment 1, two indoor pipes 9a and 9b are collectively
covered with one heat insulating material 82b. However, the indoor
pipes 9a and 9b may be covered with different heat insulating
materials. The heat insulating material 82b is mounted in the
manufacturing step of the indoor unit 1 by the air-conditioning
apparatus manufacturer.
[0053] In the lower space 115a, the temperature sensors 94a and 94b
for detecting a refrigerant leakage are provided, besides the
intake air temperature sensor 91. The temperature sensor 94a is
provided at a position adjacent to the joint 15a of the extension
pipe 10a to be in contact with the outer peripheral surface of the
extension pipe 10a. The temperature sensor 94a is provided below
the joint 15a in the vicinity of the joint 15a, for example. The
temperature sensor 94b is provided at a position adjacent to the
joint 15b of the extension pipe 10b to be in contact with the outer
peripheral surface of the extension pipe 10b. The temperature
sensor 94b is provided below the joint 15b in the vicinity of the
joint 15b, for example. In Embodiment 1, while the temperature
sensors 94a and 94b are provided at positions adjacent to the
joints 15a and 15b to which the extension pipes 10a and 10b and the
indoor pipes 9a and 9b are connected, the temperature sensors 94a
and 94b may be provided at positions adjacent to joint portions in
which refrigerant pipes (for example, the extension pipe 10a and
the indoor pipe 9a, or the extension pipe 10b and the indoor pipe
9b, and other pipes) are joined to each other by brazing, welding,
or the like, instead of the positions adjacent to the joints 15a
and 15b.
[0054] The extension pipes 10a and 10b are covered with a heat
insulating material 82c for preventing dew condensation except for
the vicinity of the joints 15a and 15b (in Embodiment 1, including
the positions where the temperature sensors 94a and 94b are
provided). In Embodiment 1, the two extension pipes 10a and 10b are
collectively covered with one heat insulating material 82c.
However, the extension pipes 10a and 10b may be covered with
different heat insulating materials. In general, the extension
pipes 10a and 10b are arranged by an installation provider who
installs the air-conditioning apparatus. The heat insulating
material 82c may be mounted before the extension pipes 10a and 10b
are purchased, or the installation provider may arrange the
extension pipes 10a and 10b and the heat insulating material 82c
separately, and mount the insulating material 82c on the extension
pipes 10a and 10b when installing the air-conditioning apparatus.
In Embodiment 1, the temperature sensors 94a and 94b are mounted on
the extension pipes 10a and 10b by the installation provider.
[0055] The vicinity of the joints 15a and 15b of the indoor pipes
9a and 9b, the vicinity of the joints 15a and 15b of the extension
pipes 10a and 10b, and the joints 15a and 15b are covered with
another heat insulating material 82a that is different from the
heat insulating materials 82b and 82c to prevent dew condensation.
The heat insulating material 82a is mounted by an installation
provider at the time of installing the air-conditioning apparatus
after the extension pipes 10a and 10b and the indoor pipes 9a and
9b are connected to each other, respectively, and then the
temperature sensors 94a and 94b are mounted on the extension pipes
10a and 10b, respectively. The heat insulating material 82a is
often packed together with the indoor unit 1 in a shipping state.
The heat insulating material 82a has a cylindrical shape divided by
a plane containing a cylinder axis, for example. The heat
insulating material 82a is wound to cover respective end portions
of the heat insulating materials 82b and 82c from the outside and
is mounted thereon with use of a band 83. The heat insulating
material 82a is closely attached to the refrigerant pipes, and
hence only a minute gap is formed between the outer peripheral
surface of each refrigerant pipe and the inner peripheral surface
of the heat insulating material 82a.
[0056] In the indoor unit 1, portions having the possibility of a
refrigerant leakage are the brazed portions W of the load-side heat
exchanger 7 and joint portions in which refrigerant pipes are
joined to each other (in Embodiment 1, joints 15a and 15b). In
general, the refrigerant leaked from the refrigerant circuit 40
under the atmospheric pressure is adiabatically expanded to be
gasified, and is diffused to the air. When the refrigerant is
adiabatically expanded and gasified, the refrigerant removes heat
from the surrounding air and the like.
[0057] Meanwhile, in Embodiment 1, the brazed portions W and the
joints 15a and 15b having a possibility of a refrigerant leakage
are covered with the heat insulating materials 82d and 82a.
Accordingly, the refrigerant that is adiabatically expanded and
gasified cannot remove heat from the air outside the heat
insulating materials 82d and 82a. Further, the heat capacity of the
heat insulating materials 82d and 82a is small, and hence the
refrigerant hardly removes heat from the heat insulating materials
82d and 82a. Thus, the refrigerant mainly removes heat from
refrigerant pipes. On the other hand, the refrigerant pipe itself
is thermally insulated from the outside air by the heat insulating
materials. Accordingly, when the heat of the refrigerant pipe is
removed by the refrigerant, the temperature of the refrigerant pipe
drops in accordance with the removed heat amount, and the dropped
temperature of the refrigerant pipe is maintained. In this way, the
temperature of the refrigerant pipe near the leakage portion drops
to an extremely-low temperature of about boiling point (for
example, in the case of HFO-1234yf, about -29 degrees C.) of the
refrigerant, and the temperature of the refrigerant pipe away from
the leakage portion also drops sequentially.
[0058] Further, the adiabatically expanded and gasified refrigerant
is hardly diffused to the air outside the heat insulating materials
82d and 82a, and remains in a minute gap between the refrigerant
pipe and the heat insulating materials 82d and 82a. Then, when the
temperature of the refrigerant pipe drops to the boiling point of
the refrigerant, the gas refrigerant remaining in the minute gap is
recondensed on the outer peripheral surface of the refrigerant
pipe. The leaking refrigerant that is liquified by recondensation
runs through the outer peripheral surface of the refrigerant pipe
or the inner peripheral surface of the heat insulating material and
flows downward in the minute gap between the refrigerant pipe and
the heat insulating material.
[0059] At this time, in the temperature sensors 94a, 94b, 94c, and
94d, the temperature of extremely-low liquid refrigerant flowing
downward in the minute gap or the temperature of the refrigerant
pipe that is dropped to the extremely-low temperature is
detected.
[0060] It is desirable that the heat insulating materials 82a, 82b,
82c, and 82d be made of closed cell foamed resin (e.g., foamed
polyethylene). With this configuration, it is possible to prevent
leaking refrigerant existing in the minute gap between the
refrigerant pipe and the heat insulating material from leaking to
the outside air by passing through the heat insulating material.
Further, the heat capacity of a heat insulating material is also
decreased.
[0061] FIG. 6 is a schematic diagram for illustrating a
modification example of a configuration of the heat insulating
material 82d illustrated in FIG. 5. In FIG. 6, as the brazed
portions W, there are illustrated a brazed portion W1 between the
indoor pipe 9a and the header main pipe 61, a brazed portion W2
between the header main pipe 61 and a header branch pipe 62-1, a
brazed portion W3 between the header main pipe 61 and a header
branch pipe 62-2, a brazed portion W4 between the header main pipe
61 and a header branch pipe 62-3, a brazed portion W5 between the
indoor pipe 9b and an indoor refrigerant branch pipe 63-1, and a
brazed portion W6 between the indoor pipe 9b and an indoor
refrigerant branch pipe 63-2. Further, in FIG. 6, among the brazed
portions W illustrated in FIG. 5, the brazed portion W between the
header branch pipe 62 and the heat transfer tube 71, the brazed
portion W between the indoor refrigerant branch pipe 63 and the
heat transfer tube 71, and the brazed portion W between the
hair-pin pipe 72 and the U bent pipe 73 are not shown.
[0062] As illustrated in FIG. 6, the heat insulating material 82d
is constructed of at least four heat insulating members 82d1, 82d2,
82d3, and 82d4 that are linked integrally. That is, substantially a
unit of heat insulating material 82d is formed of the plurality of
heat insulating members 82d1, 82d2, 82d3, and 82d4. Each of the
heat insulating members 82d1, 82d2, 82d3, and 82d4 may be a pair of
heat insulating members closely attached to each other via mating
surfaces. In this case, when it is assumed that a pair of heat
insulating members forms a set, the heat insulating material 82d is
constructed of at least four sets of heat insulating members 82d1,
82d2, 82d3, and 82d4.
[0063] Among the heat insulating members 82d1, 82d2, 82d3, and
82d4, two adjacent heat insulating members are arranged such that
end portions thereof (for example, an end portion 82d1a of the heat
insulating member 82d1 and an end portion 82d2a of the heat
insulating member 82d2) are closely attached to each other over the
entire circumference. In this way, the heat insulating members
82d1, 82d2, 82d3, and 82d4 are integrated with no gap as the unit
of heat insulating material 82d.
[0064] For example, the temperature sensor 94c is covered with the
heat insulating member 82d1. On the other hand, the brazed portions
W1, W2, W3, W4, W5, and W6 are covered with any of the heat
insulating members 82d2, 82d3, and 82d4 rather than the heat
insulating member 82d1. However, the heat insulating members 82d1,
82d2, 82d3, and 82d4 are integrated as the unit of heat insulating
material 82d, and hence, when refrigerant leaks at any of the
brazed portions W1, W2, W3, and W4, the temperature of
extremely-low temperature liquid refrigerant flowing downward in
the minute gap along the refrigerant pipe or the temperature of the
refrigerant pipe that is lowered to extremely-low temperature is
detected by the temperature sensor 94c. Further, when refrigerant
leaks in any one of the brazed portions W5 and W6, the leaking
refrigerant moves within the range of the unit of heat insulating
material 82d along the minute gap between the mating surfaces of
the respective heat insulating members 82d1, 82d2, 82d3, and 82d4
or a minute gap between two adjacent heat insulating members among
the heat insulating members 82d1, 82d2, 82d3, and 82d4.
Accordingly, even in the case where refrigerant leaks in any one of
the brazed portions W5 and W6, the temperature of the extremely-low
temperature liquid refrigerant flowing downward in the minute gap
or the temperature of the refrigerant pipe in which the temperature
is decreased to extremely-low temperature is detected by the
temperature sensor 94c.
[0065] That is, in the example illustrated in FIG. 6, the
temperature sensor 94c and the brazed portions W1, W2, W3, W4, W5,
and W6 are integrally covered with the unit of heat insulating
material 82d constructed of the heat insulating members 82d1, 82d2,
82d3, and 82d4. Accordingly, extremely-low temperature caused by a
leakage of refrigerant in any of the brazed portions W1, W2, W3,
W4, W5, and W6 can be detected by the temperature sensor 94c.
[0066] Similarly, in the example illustrated in FIG. 6, the
temperature sensor 94d and the brazed portions W1, W2, W3, W4, W5,
and W6 are integrally covered with the unit of heat insulating
material 82d constructed of the heat insulating members 82d1, 82d2,
82d3, and 82d4. Accordingly, extremely-low temperature caused by a
leakage of refrigerant in any of the brazed portions W1, W2, W3,
W4, W5, and W6 can also be detected by the temperature sensor
94d.
[0067] FIG. 7 is a schematic diagram for illustrating another
modification example of the configuration of the heat insulating
material 82d illustrated in FIG. 5. In the example illustrated in
FIG. 7, among the heat insulating members 82d1, 82d2, 82d3, and
82d4, two adjacent heat insulating members are arranged such that
end surfaces thereof (for example, an end surface 82d1b of the heat
insulating member 82d1 and an end surface 82d2b of the heat
insulating member 82d2) are closely attached to each other over the
entire circumference. Even with the configuration illustrated in
FIG. 7, extremely-low temperature caused by a leakage of
refrigerant in any of the brazed portions W1, W2, W3, W4, W5, and
W6 can be detected by the temperature sensors 94c and 94d.
[0068] As illustrated in FIG. 6 and FIG. 7, the heat insulating
material 82d is not necessarily constructed of one heat insulating
member or a pair of heat insulating members but may be constructed
of a plurality of heat insulating members or a plurality of sets of
heat insulating members that are linked integrally. With such a
configuration, the size of each of the heat insulating members
82d1, 82d2, 82d3, and 82d4 can be decreased to an easily mountable
level, and hence the workability of manufacturing the indoor unit 1
can be improved. Further, heat insulating members having the same
shape can be used as the heat insulating members 82d1, 82d2, 82d3,
and 82d4. Therefore, the heat insulating members can be
standardized, that is, manufacturing cost can be reduced.
[0069] FIG. 8 is a graph for showing exemplary temporal changes of
the temperature detected by the temperature sensor 94b when
refrigerant is caused to leak from the joint 15b in the indoor unit
1 of the air-conditioning apparatus according to Embodiment 1. In
the graph, the horizontal axis represents the elapsed time
(seconds) from the start of leakage, and the vertical axis
represents the temperature (degrees C.). In FIG. 8, a temporal
change of the temperature when the leakage speed is 1 kg/h and a
temporal change of the temperature when the leakage speed is 10
kg/h are shown together. As refrigerant, HFO-1234yf is used.
[0070] As shown in FIG. 8, when the leaking refrigerant is
adiabatically expanded and gasified, the detected temperature
detected by the temperature sensor 94b begins to decrease
immediately after the start of leakage. When liquifaction due to
recondensation of refrigerant begins after several seconds to over
ten seconds elapsed from the start of leakage, the detected
temperature detected by the temperature sensor 94b suddenly drops
to about -29 degrees C., which is the boiling point of HFO-1234yf.
Then, the detected temperature detected by the temperature sensor
94b is maintained at about -29 degrees C.
[0071] As described above, because the refrigerant leakage portion
is covered with a heat insulating material, it is possible to
detect a temperature drop due to a refrigerant leakage without time
delay. Further, because a refrigerant leakage portion is covered
with a heat insulating material, even in the case where the leakage
speed is 1 kg/h, which is relatively low, it is possible to detect
a temperature drop due to a refrigerant leakage with high
responsiveness.
[0072] FIG. 9 is a flowchart for illustrating an example of
refrigerant leakage detection processing to be performed by the
controller 30 of the air-conditioning apparatus of Embodiment 1.
The refrigerant leakage detection processing is performed
repeatedly with predetermined time intervals only when power is
supplied to the air-conditioning apparatus (that is, a breaker for
supplying power to the air-conditioning apparatus is on) and the
indoor fan 7f is stopped, for example. During an operation of the
indoor fan 7f, the air in the indoor space is stirred, Thus, even
if refrigerant has leaked, the refrigerant concentration does not
become high locally. Accordingly, in Embodiment 1, the refrigerant
leakage detection processing is performed only when the indoor fan
7f is stopped. In Embodiment 1, the temperature sensor for
detecting a refrigerant leakage is accommodated in the casing 111
of the indoor unit 1 along with the indoor fan 7f, but even in the
case where the temperature sensor for detecting a refrigerant
leakage is not accommodated in the casing 111 of the indoor unit 1,
the refrigerant leakage detection processing may be performed only
when the indoor fan 7f is stopped. In this way, it is possible to
prevent the refrigerant concentration in the indoor space from
becoming high locally more reliably. In the case where a battery or
an uninterruptible power source device capable of supplying power
to the indoor unit 1 is mounted, the refrigerant leakage detection
processing may be performed even when the breaker is off.
[0073] In Embodiment 1, the refrigerant leakage detection
processing procedures using the respective temperature sensors 94a,
94b, 94c, and 94d are performed in parallel. In the following
description, only the refrigerant leakage detection processing
using the temperature sensor 94b is described as an example.
[0074] In Step S1 of FIG. 9, the controller 30 acquires information
of a detected temperature detected by the temperature sensor
94b.
[0075] Next, in Step S2, it is determined whether or not the
detected temperature detected by the temperature sensor 94b is
lower than a preset threshold temperature (for example, -10 degrees
C.). The threshold temperature may be set to a lower limit (for
example, 3 degrees C.; the detail is described later) of the
evaporating temperature of the load-side heat exchanger 7 at the
time of cooling operation, for example. When it is determined that
the detected temperature is lower than the threshold temperature,
the processing proceeds to Step S3. When it is determined that the
detected temperature is equal to or higher than the threshold
temperature, the processing ends.
[0076] In Step S3, it is determined that refrigerant has leaked.
When determining that refrigerant has leaked, the controller 30 may
operate the indoor fan 7f. In this way, the air in the indoor space
is stirred, and the leaking refrigerant can be diffused. Thus, it
is possible to prevent the refrigerant concentration from becoming
high locally. Accordingly, even in the case where flammable
refrigerant is used as refrigerant, it is possible to prevent a
region in which a refrigerant concentration is at a flammable level
from being formed.
[0077] Further, when determining that refrigerant has leaked, the
controller 30 may set the system state of the air-conditioning
apparatus to "abnormal" to not allow operations of those components
other than the indoor fan 7f.
[0078] Further, when determining that refrigerant has leaked, the
controller 30 may inform the user of abnormality by using an
informing unit (display unit or sound output unit) provided on the
operation unit 26. For example, the controller 30 displays, on the
display unit provided on the operation unit 26, an instruction such
as "gas leakage occurs, open the window". In this way, it is
possible to immediately allow the user to recognize that
refrigerant has leaked and that an action such as ventilation is
required to be taken. Accordingly, it is possible to prevent the
refrigerant concentration from becoming high locally more
reliably.
[0079] FIG. 10 is a flowchart for illustrating another example of
the refrigerant leakage detection processing to be performed by the
controller 30 of the air-conditioning apparatus according to
Embodiment 1. In Step S11 of FIG. 10, the controller 30 acquires
information of a detected temperature detected by the temperature
sensor 94b.
[0080] In Step S12, the controller 30 calculates a temporal change
of the detected temperature detected by the temperature sensor 94b.
For example, in the case where the detected temperature detected by
the temperature sensor 94b is acquired every one minute, a value
obtained by subtracting the detected temperature that was acquired
one minute before from the currently acquired detected temperature
may be used as a temporal change of the detected temperature. When
the detected temperature is decreasing, the temporal change of the
detected temperature takes a negative value. Accordingly, when the
detected temperature is decreasing, the temporal change of the
detected temperature decreases as the detected temperature changes
more drastically.
[0081] In Step S13, it is determined whether or not the detected
temperature detected by the temperature sensor 94b is lower than a
threshold value (for example, -20 degrees C/minute). When it is
determined that the temporal change of the detected temperature is
lower than the threshold value, the processing proceeds to Step
S14. When it is determined that the temporal change of the detected
temperature is equal to or larger than the threshold value, the
processing ends.
[0082] In Step S14, it is determined that refrigerant has leaked,
and the same processing as that of Step S3 of FIG. 9 is
performed.
[0083] Next, still another example of the refrigerant leakage
detection processing is described. As each temperature sensor, a
thermistor in which electric resistance is changed in accordance
with a change of the temperature is used. The electric resistance
of a thermistor decreases when the temperature increases, while the
electric resistance increases when the temperature decreases. On
the substrate, a fixed resistor connected in series to the
thermistor is mounted. The thermistor and the fixed resistor are
applied with a voltage of DC 5 V, for example. The electric
resistance of the thermistor is changed in accordance with the
temperature, and hence the voltage (divided voltage) applied to the
thermistor is changed in accordance with the temperature. The
controller 30 converts a value of the voltage applied to the
thermistor into the temperature, to thereby acquire the detected
temperature detected by each temperature sensor.
[0084] The range of resistance values of a thermistor is set based
on the range of temperature that is to be detected. When the
voltage applied to the thermistor is out of the voltage range
corresponding to the detected temperature range, an error
indicating that the temperature is out of the detected temperature
range may be detected by the controller 30 in some cases.
[0085] Meanwhile, in the configuration illustrated in FIG. 3 to
FIG. 5 and other figures, temperature sensors configured to detect
a refrigerant temperature of the load-side heat exchanger 7 (for
example, the heat exchanger liquid pipe temperature sensor 92 and
the heat exchanger two-phase pipe temperature sensor 93) and the
temperature sensors 94a, 94b, 94c, and 94d for detecting a
refrigerant leakage are provided independently. However, for
example, the heat exchanger liquid pipe temperature sensor 92 may
also serve as the temperature sensor 94d for detecting a
refrigerant leakage. The heat exchanger liquid pipe temperature
sensor 92 is covered with the heat insulating material 82d, which
is the same as the heat insulating material 82d covering the brazed
portion W, and is provided at a position thermally connected to the
brazed portion W via a refrigerant pipe. Accordingly, it is
possible to detect an extremely-low temperature phenomenon near the
brazed portion W.
[0086] The detected temperature range of the temperature sensor
configured to detect a refrigerant temperature of the load-side
heat exchanger 7 is set based on the temperature range of the
load-side heat exchanger 7 at the time of normal operation. For
example, the refrigerant circuit 40 is controlled such that the
evaporating temperature at the time of cooling operation does not
decrease to 3 degrees C. or lower, by cryoprotection of the
load-side heat exchanger 7. Further, the refrigerant circuit 40 is
controlled such that the condensing temperature at the time of
heating operation does not increase to 60 degrees C. or higher, by
condensing temperature (condensing pressure) excessive rise
prevention protection for preventing failure of the compressor 3,
for example. In this case, the temperature range of the load-side
heat exchanger 7 at the time of normal operation is from 3 degrees
C. to 60 degrees C.
[0087] As described above, when a refrigerant leakage occurs in
Embodiment 1, the temperature sensor near the leakage portion
detects an extremely-low temperature that is greatly different from
the temperature range of the load-side heat exchanger 7. In this
case, when an error indicating that the temperature is out of the
detected temperature range of the temperature sensor is detected,
the controller 30 may determine that an extremely-low temperature
is detected by the temperature sensor to determine that refrigerant
has leaked.
[0088] With this configuration, similar to the configuration
illustrated in FIG. 3 to FIG. 5 and other figures, a leakage of
refrigerant can be detected reliably with high responsiveness for a
long period of time. Further, with this configuration, the number
of temperature sensors can be reduced, and thus the manufacturing
cost of the air-conditioning apparatus can be reduced.
[0089] Next, a modification example of the refrigeration cycle
apparatus according to Embodiment 1 is described. In the
configuration illustrated in FIG. 3 to FIG. 5 and other figures,
while the temperature sensors 94a, 94b, 94c, and 94d are provided
below the brazed portions W or joint portions (for example, joints
15a and 15b), the temperature sensors 94a, 94b, 94c, and 94d may be
provided above or beside the brazed portions W or joint portions.
For example, the temperature sensors 94a and 94b may be provided at
positions above or beside the joints 15a and 15b of the indoor
pipes 9a and 9b in the lower space 115a illustrated in FIG. 5, and
where the temperature sensors 94a and 94b are covered with the heat
insulating material 82b (for example, positions where the
temperature sensors 94a and 94b are further covered with the heat
insulating material 82a). With this configuration, the temperature
sensors 94a and 94b can be mounted on the indoor pipe 9a and 9b by
the air-conditioning apparatus manufacturer. Accordingly, the need
to mount the temperature sensors 94a and 94b at the time of
installing the air-conditioning apparatus is eliminated, and hence
the installation workability can be improved.
[0090] The gaps between the outer peripheral surfaces of the indoor
pipes 9a and 9b and the inner peripheral surfaces of the heat
insulating materials 82a and 82b are minute, and hence the
extremely-low temperature refrigerant liquified by recondensation
in the vicinity of the joints 15a and 15b moves not only downward
but also upward and sideward by the capillary phenomenon.
Accordingly, even when the temperature sensors 94a and 94b are
provided above or beside the joints 15a and 15b, a temperature of
the extremely-low temperature refrigerant can be detected.
[0091] Further, the heat exchanger two-phase pipe temperature
sensor 93 may also serve as the temperature sensor 94d for
detecting a refrigerant leakage, for example.
[0092] For example, when a refrigerant leakage occurs at one brazed
portion W, extremely-low temperature refrigerant, which is
liquified by recondensation, moves within the range of the heat
insulating material 82d along a minute gap between the heat
insulating material 82d and the refrigerant pipe or a minute gap
between the mating surfaces of the heat insulating material 82d, by
the capillary phenomenon. The heat exchanger two-phase pipe
temperature sensor 93 is integrally covered with the heat
insulating material 82d, which is the same as the heat insulating
material covering the brazed portions W of the U bent pipe 73 to
which the heat exchanger two-phase pipe temperature sensor 93 is
provided, other U bent pipes 73, the indoor pipes 9a and 9b, the
header main pipe 61, and other pipes. Accordingly, the heat
exchanger two-phase pipe temperature sensor 93 is capable of
detecting a temperature of the extremely-low temperature
refrigerant that has leaked at each brazed portion W covered with
the heat insulating material 82d.
[0093] As described above, the refrigeration cycle apparatus
according to Embodiment 1 includes: the refrigerant circuit 40 in
which refrigerant circulates, the temperature sensors 94a, 94b,
94c, and 94d provided at positions on the refrigerant circuit 40,
the positions being adjacent to brazed portions (for example, the
brazed portions W of the load-side heat exchanger 7) or the
position being adjacent to joint portions (for example, the joints
15a and 15b) in which refrigerant pipes are joined to each other;
and the controller 30 configured to determine whether or not the
refrigerant has leaked based on a detected temperature detected by
the temperature sensors 94a, 94b, 94c, and 94d. The temperature
sensors 94a, 94b, 94c, and 94d are covered with the heat insulating
materials 82a, 82b, and 82d together with the brazed portions or
the joint portions.
[0094] With this configuration, the temperature sensors 94a, 94b,
94c, and 94d can be used as refrigerant detection units. Therefore,
a leakage of refrigerant can be detected reliably for a long period
of time. Further, with this configuration, the temperature sensors
94a, 94b, 94c, and 94d are covered with the heat insulating
materials 82a, 82b, and 82d together with the brazed portions or
the joint portions. Therefore, it is possible to detect a
temperature drop due to a refrigerant leakage in the brazed
portions or the joint portions without time delay. Accordingly, a
leakage of refrigerant can be detected with high
responsiveness.
[0095] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the controller 30 may be configured to determine that
the refrigerant has leaked when the detected temperature is lower
than the threshold temperature.
[0096] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the controller 30 may be configured to determine that
the refrigerant has leaked when a temporal change of the detected
temperature is lower than the threshold value.
[0097] Further, the refrigeration cycle apparatus according to
Embodiment 1 may further include the fan (for example, indoor fan
7f), and the controller 30 may be configured to determine whether
or not the refrigerant has leaked only when the fan is stopped.
[0098] Further, the refrigeration cycle apparatus according to
Embodiment 1 may further include the fan (for example, the indoor
fan 7f) and the casing (for example, the casing 111) configured to
accommodate the fan. The temperature sensors (for example,
temperature sensors 94a, 94b, 94c, and 94d) may be accommodated in
the casing, and the controller 30 may be configured to determine
whether or not the refrigerant has leaked only when the fan is
stopped.
[0099] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the temperature sensors 94a, 94b, 94c, and 94d may be
provided below the brazed portions or the joint portions.
[0100] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the temperature sensors 94a, 94b, 94c, and 94d may be
provided above or beside the brazed portions or the joint
portions.
[0101] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the temperature sensors 94a, 94b, 94c, and 94d may be
covered with the heat insulating materials 82a, 82b, and 82d that
are the same as the heat insulating materials 82a, 82b, and 82d
covering the brazed portions or the joint portions.
[0102] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the heat insulating material 82d may be constructed
of the plurality of heat insulating members 82d1, 82d2, 82d3, and
82d4.
[0103] Further, in the refrigeration cycle apparatus according to
Embodiment 1, two adjacent heat insulating members among the
plurality of heat insulating members 82d1, 82d2, 82d3, and 82d4 may
be arranged such that end portions thereof (for example, the end
portion 82d1a of the heat insulating member 82d1 and the end
portion 82d2a of the heat insulating member 82d2) overlap with each
other.
[0104] Further, in the refrigeration cycle apparatus according to
Embodiment 1, two adjacent heat insulating members among the
plurality of heat insulating members 82d1, 82d2, 82d3, and 82d4 may
be arranged such that end surfaces thereof (for example, the end
surface 82d1b of the heat insulating member 82d1 and the end
surface 82d2b of the heat insulating member 82d2) are in contact
with each other.
[0105] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the brazed portions or the joint portions may be
covered with first heat insulating members 82d2, 82d3, and 82d4
among the plurality of heat insulating members 82d1, 82d2, 82d3,
and 82d4, and the temperature sensor 94c may be covered with a
second heat insulating member 82d1 among the plurality of heat
insulating members 82d1, 82d2, 82d3, and 82d4.
[0106] Further, in the refrigeration cycle apparatus according to
Embodiment 1, the temperature sensors configured to detect the
refrigerant temperature (for example, liquid pipe temperature or
two-phase pipe temperature) of the heat exchanger may also serve as
the temperature sensors 94a, 94b, 94c, and 94d.
[0107] Further, a refrigerant leakage detection method according to
Embodiment 1 includes: detecting a temperature of a position on the
refrigerant circuit 40 in which refrigerant circulates, the
position being adjacent to brazed portions (for example, the brazed
portions W of load-side heat exchanger 7) and being covered with
the heat insulating material 82d together with the brazed portions,
or the position being adjacent to joint portions in which
refrigerant pipes are joined to each other (for example, the joints
15a and 15b) and being covered with the heat insulating materials
82a and 82b together with the joint portions; and determining
whether or not the refrigerant has leaked based on the temperature.
With this configuration, it is possible to detect a leakage of
refrigerant reliably with high responsiveness for a long period of
time.
Other Embodiments
[0108] The present invention can be modified in various manners
without being limited to Embodiment 1.
[0109] For example, while a floor type indoor unit is exemplarily
described as the indoor unit 1 in Embodiment 1, the present
invention is applicable to indoor units of other types such as a
ceiling cassette type, a ceiling concealed type, a ceiling
suspended type, and a wall type.
[0110] Further, while Embodiment 1 exemplarily describes a
configuration in which a temperature sensor for detecting a
refrigerant leakage is provided in the indoor unit 1, a temperature
sensor for detecting a refrigerant leakage may be provided in the
outdoor unit 2 (for example, in the casing of the outdoor unit 2).
In this case, the temperature sensor for detecting a refrigerant
leakage is provided at a position adjacent to a brazed portion of
the heat source-side heat exchanger 5, for example, and is covered
with a heat insulating material together with the brazed portion.
Alternatively, the temperature sensor for detecting a refrigerant
leakage is provided at a position in the outdoor unit 2, which is
adjacent to a joint portion in which refrigerant pipes are joined
to each other, and is covered with a heat insulating material
together with the joint portion. The controller 30 determines
whether or not the refrigerant has leaked based on the detected
temperature detected by the temperature sensor for detecting a
refrigerant leakage. With this configuration, it is possible to
detect a leakage of refrigerant in the outdoor unit 2 reliably with
high responsiveness for a long period of time. During an operation
of the outdoor fan 5f, the air around the outdoor unit 2 is
stirred. Accordingly, even if refrigerant has leaked in the outdoor
unit 2, the refrigerant concentration does not increase locally
around the outdoor unit 2. Therefore, in the case where the outdoor
fan 5f and the temperature sensor are accommodated in the casing of
the outdoor unit 2, for example, determination of whether or not
the refrigerant has leaked with use of the temperature sensor may
be performed only when the outdoor fan 5f is stopped.
[0111] As brazed portions of the refrigerant circuit 40, while
Embodiment 1 mainly describes the brazed portions W in the
load-side heat exchanger 7 and brazed portions in the heat
source-side heat exchanger 5 as examples, the present invention is
not limited thereto. The brazed portions of the refrigerant circuit
40 exist at other positions such as between the indoor pipes 9a and
9b and the joints 15a and 15b in the indoor unit 1, between the
suction pipe 11 and the compressor 3 in the outdoor unit 2, and
between the discharge pipe 12 and the compressor 3 in the outdoor
unit 2, besides those in the load-side heat exchanger 7 and the
heat source-side heat exchanger 5. Accordingly, a temperature
sensor for detecting a refrigerant leakage may be provided at a
position on the refrigerant circuit 40, which is adjacent to a
brazed portion other than those in the load-side heat exchanger 7
and the heat source-side heat exchanger 5, and may be covered with
a heat insulating material together with the brazed portion. Even
with this configuration, a leakage of refrigerant in the
refrigerant circuit 40 can be detected reliably with high
responsiveness for a long period of time.
[0112] Further, while Embodiment 1 mainly describes the joints 15a
and 15b of the indoor unit 1 as examples of joint portions of the
refrigerant circuit 40, the present invention is not limited
thereto. The joint portions of the refrigerant circuit 40 also
include the joints 16a and 16b and other joints of the outdoor unit
2, Accordingly, the temperature sensor for detecting a refrigerant
leakage may be provided adjacent to a joint portion other than the
joints 15a and 15b (for example, the joints 16a and 16b) on the
refrigerant circuit 40, and may be covered with a heat insulating
material together with the joint portion. Even with this
configuration, a leakage of refrigerant in the refrigerant circuit
40 can be detected reliably with high responsiveness for a long
period of time,
[0113] Further, while Embodiment 1 describes an air-conditioning
apparatus as an example of a refrigeration cycle apparatus, the
present invention is applicable to other refrigeration cycle
apparatus s such as a heat pump water heater, a chiller, and a
showcase.
[0114] Further, the above-mentioned embodiments and modification
examples can be carried out in combination with each other,
REFERENCE SIGNS LIST
[0115] 1 indoor unit 2 outdoor unit 3 compressor 4 refrigerant flow
path switching device 5 heat source-side heat exchanger 5f outdoor
fan 6 decompression device 7 load-side heat exchanger 7f indoor fan
9a, 9b indoor pipe 10a, 10b extension pipe 11 suction pipe 12
discharge pipe
[0116] 13a, 13b extension pipe connection valve 14a, 14b, 14c
service port
[0117] 15a, 15b, 16a, 16b joint 20 partition 20a air passage
opening port 25 electrical component box 26 operation unit 30
controller 40 refrigerant circuit
[0118] 61 header main pipe 62, 62-1, 62-2, 62-3 header branch pipe
63, 63-1, 63-2 indoor refrigerant branch pipe 70 fin 71 heat
transfer tube 71a, 71bend portion 72 hair-pin pipe 73 U bent pipe
81 air passage 82a, 82b, 82c, 82d heat insulating material 82d1,
82d2, 82d3, 82d4 heat insulating member
[0119] 82d1a, 82d2a end portion 82d1b, 82d2b end surface 83 band 91
intake air temperature sensor 92 heat exchanger liquid pipe
temperature sensor
[0120] 93 heat exchanger two-phase pipe temperature sensor 94a,
94b, 94c, 94d temperature sensor 107 impeller 108 fan casing 108a
air outlet opening port 108b suction opening port 111 casing 112
air inlet 113 air outlet 114a first front panel 114b second front
panel 114c third front panel 115a lower space 115b upper space W,
W1, W2, W3, W4, W5, W6 brazed portion
* * * * *