U.S. patent application number 15/780336 was filed with the patent office on 2018-12-13 for air-conditioning apparatus.
The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Kazuki OKADA, Mizuo SAKAI, Masahiro TAKAMURA, Masafumi TOMITA.
Application Number | 20180356138 15/780336 |
Document ID | / |
Family ID | 59500764 |
Filed Date | 2018-12-13 |
United States Patent
Application |
20180356138 |
Kind Code |
A1 |
TAKAMURA; Masahiro ; et
al. |
December 13, 2018 |
AIR-CONDITIONING APPARATUS
Abstract
An air-conditioning apparatus includes a refrigerant circuit in
which a compressor, a flow switching device, an outdoor heat
exchanger, an expansion device, and an indoor heat exchanger are
connected by pipes and through which refrigerant flows, and a
control device controlling an operation of the refrigerant circuit
to perform switching between a heating operation and a defrosting
operation. The control device includes a determination unit that
determines, based on operation information regarding the
refrigerant circuit, during the heating operation, whether to
change a requirement for starting the defrosting operation, a
changing unit that changes the requirement for starting the
defrosting operation in accordance with a result of determination
by the determination unit, and a switching unit that, when the
requirement for starting the defrosting operation is satisfied,
causes the flow switching device to perform switching to start the
defrosting operation.
Inventors: |
TAKAMURA; Masahiro; (Tokyo,
JP) ; TOMITA; Masafumi; (Tokyo, JP) ; OKADA;
Kazuki; (Tokyo, JP) ; SAKAI; Mizuo; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
59500764 |
Appl. No.: |
15/780336 |
Filed: |
February 5, 2016 |
PCT Filed: |
February 5, 2016 |
PCT NO: |
PCT/JP2016/053458 |
371 Date: |
May 31, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24F 11/41 20180101;
F25B 2700/171 20130101; F24F 11/89 20180101; F24F 2120/10 20180101;
F25B 2700/2106 20130101; F25B 2600/01 20130101; F25B 47/025
20130101; F25B 47/02 20130101 |
International
Class: |
F25B 47/02 20060101
F25B047/02 |
Claims
1. An air-conditioning apparatus comprising: a refrigerant circuit
in which a compressor, a flow switching device, an outdoor heat
exchanger, an expansion device, and an indoor heat exchanger are
connected by pipes, and through which refrigerant flows; and a
processor configured to control an operation of the refrigerant
circuit to perform switching between a heating operation and a
defrosting operation, wherein the processor is configured to:
determine, based on operation information regarding the refrigerant
circuit, during the heating operation, whether or not to change a
requirement for starting the defrosting operation; change the
requirement for starting the defrosting operation in accordance
with a result of determination of whether or not to change a
requirement for starting the defrosting operation and a result of
determination of whether or not it is presumed that the heating
operation is required; and cause, when the requirement for starting
the defrosting operation is satisfied, the flow switching device to
perform switching to start the defrosting operation.
2. The air-conditioning apparatus of claim 1, further comprising: a
human body detection device configured to detect presence or
absence of a human body, wherein the processor is configured to
change the requirement for starting the defrosting operation in
accordance with the result of determination of whether or not to
change the requirement for stating the defrosting operation and a
result of detection by the human body detection device.
3. The air-conditioning apparatus of claim 1, further comprising: a
remote controller configured to transmit a stop signal to stop the
operation of the refrigerant circuit, wherein the processor is
configured to allow starting the defrosting operation upon
receiving the stop signal from the remote controller, and wherein
when starting the defrosting operation is allowed, the processor
causes the flow switching device to perform switching to start the
defrosting operation.
4. The air-conditioning apparatus of claim 1, wherein the processor
is configured to allow starting the defrosting operation upon
receiving a thermo-off signal indicating a thermo-off state in
which the heating operation is temporarily stopped since an actual
indoor temperature is higher than a set temperature, and wherein
when starting the defrosting operation is allowed, the processor
causes the flow switching device to perform switching to start the
defrosting operation.
5. The air-conditioning apparatus of claim 1, further comprising:
an outdoor heat-exchanger temperature detection device configured
to detect a temperature of the outdoor heat exchanger, wherein the
requirement for starting the defrosting operation is that the
temperature detected by the outdoor heat-exchanger temperature
detection device is at or below an outdoor heat-exchanger
temperature threshold, and wherein the processor is configured to
change, during the heating operation, the outdoor heat-exchanger
temperature threshold to an outdoor heat-exchanger temperature
relaxed threshold higher than the outdoor heat-exchanger
temperature threshold in accordance with the operation information
regarding the refrigerant circuit.
6. The air-conditioning apparatus of claim 1, further comprising:
an outdoor temperature detection device configured to detect an
outdoor temperature, wherein the operation information is the
temperature detected by the outdoor temperature detection device,
wherein the processor is configured to determine whether or not the
temperature detected by the outdoor temperature detection device is
at or below an outdoor temperature threshold, and wherein when it
is determined that the temperature detected by the outdoor
temperature detection device is at or below the outdoor temperature
threshold, the processor changes the requirement for starting the
defrosting operation.
7. The air-conditioning apparatus of claim 1, further comprising: a
frequency detection device configured to detect an operation
frequency of the compressor, wherein the operation information is
the operation frequency detected by the frequency detection device,
wherein the processor is configured to determine whether or not the
operation frequency detected by the frequency detection device is
at or above a frequency threshold, and wherein when the processor
determines that the operation frequency detected by the frequency
detection device is at or above the frequency threshold, the
processor changes the requirement for starting the defrosting
operation.
8. The air-conditioning apparatus of claim 1, further comprising: a
time measurement device configured to measure an operation time
period of the defrosting operation, wherein the operation
information is the operation time period measured by the time
measurement device, wherein the processor is configure to determine
whether or not an operation time period of a preceding defrosting
operation measured by the time measurement device is at or above a
time threshold, and wherein when it is determined that the
operation time period of the preceding defrosting operation
measured by the time measurement device is at or above the time
threshold, the processor changes the requirement for starting the
defrosting operation.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air-conditioning
apparatus that removes frost formed on an outdoor heat
exchanger.
BACKGROUND ART
[0002] An air-conditioning apparatus known in the art includes a
refrigerant circuit in which a compressor, a flow switching device,
an outdoor heat exchanger, an expansion unit, and an indoor heat
exchanger are connected by pipes. In a heating operation, when a
pressure saturation temperature in the outdoor heat exchanger
functioning as an evaporator is at or below the dew point
temperature of outdoor air and is at or below the freezing point of
water, frost forms on the outdoor heat exchanger. When the outdoor
heat exchanger is frosted, the air-conditioning apparatus performs
a defrosting operation of removing frost on the outdoor heat
exchanger, thus reducing worsening of the heat exchange performance
of the outdoor heat exchanger, which is caused by a frost formation
phenomenon.
[0003] Patent Literature 1 discloses an air-conditioning apparatus
including an outdoor heat-exchanger temperature sensor, an outdoor
air temperature sensor, and a human body sensor. As described in
Patent Literature 1, when an output of the outdoor heat-exchanger
temperature sensor, and an output of the outdoor air temperature
sensor meet requirements for starting the defrosting operation and
the human body sensor detects the absence of a person, the
defrosting operation is started. The apparatus with such a
configuration is intended to avoid performing the defrosting
operation while a person is present in an indoor space, and to
maintain comfortability.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2011-185535
SUMMARY OF INVENTION
Technical Problem
[0005] The requirements for starting the defrosting operation in
the air-conditioning apparatus disclosed in Patent Literature 1 are
fixed. If the requirements for starting the defrosting operation
are satisfied, the defrosting operation will not be performed as
long as a person is present in the indoor space, resulting in
worsening of the heat exchange performance of the outdoor heat
exchanger. As described above, the air-conditioning apparatus
disclosed in Patent Literature 1 fails to accurately determine
whether to perform the defrosting operation.
[0006] The present invention has been made to solve the above
problem, and aims to provide an air-conditioning apparatus which
determines whether to perform a defrosting operation or not with a
higher accuracy.
Solution to Problem
[0007] An air-conditioning apparatus according to an embodiment of
the present invention includes: a refrigerant circuit in which a
compressor, a flow switching device, an outdoor heat exchanger, an
expansion unit, and an indoor heat exchanger are connected by
pipes, and through which refrigerant flows; and a control unit
configured to control an operation of the refrigerant circuit to
perform switching between a heating operation and a defrosting
operation. The control unit includes: a determination unit that
determines, based on operation information regarding the
refrigerant circuit, during the heating operation, whether to
change a requirement for starting the defrosting operation or not;
a changing unit that changes the requirement for starting the
defrosting operation in accordance with a result of determination
by the determination unit; and a switching unit that, when the
requirement for starting the defrosting operation is satisfied,
causes the flow switching device to perform switching such that the
defrosting operation is started.
Advantageous Effects of Invention
[0008] According to the embodiment of the present invention, the
requirement for starting the defrosting operation is changed based
on the determination result based on the operation information. It
can be therefore possible to accurately determine whether to
perform the defrosting operation or not.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a circuit diagram illustrating an air-conditioning
apparatus 1 according to Embodiment 1 of the present invention.
[0010] FIG. 2 is a block diagram illustrating a control device 30
of the air-conditioning apparatus 1 according to Embodiment 1 of
the present invention.
[0011] FIG. 3 is a flowchart illustrating an operation of the
air-conditioning apparatus 1 according to Embodiment 1 of the
present invention.
[0012] FIG. 4 is a block diagram illustrating a control unit 130 of
an air-conditioning apparatus 100 according to Embodiment 2 of the
present invention.
[0013] FIG. 5 is a block diagram illustrating a control unit 230 of
an air-conditioning apparatus 200 according to Embodiment 3 of the
present invention.
[0014] FIG. 6 is a block diagram illustrating a control unit 330 of
an air-conditioning apparatus 300 according to Embodiment 4 of the
present invention.
[0015] FIG. 7 is a flowchart illustrating an operation of the
air-conditioning apparatus 300 according to Embodiment 4 of the
present invention.
[0016] FIG. 8 is a block diagram illustrating a control unit 430 of
an air-conditioning apparatus 400 according to Embodiment 5 of the
present invention.
[0017] FIG. 9 is a flowchart illustrating an operation of the
air-conditioning apparatus 400 according to Embodiment 5 of the
present invention.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0018] Embodiments of an air-conditioning apparatus according to
the present invention will be described below with reference to the
drawings. FIG. 1 is a circuit diagram illustrating an
air-conditioning apparatus 1 according to Embodiment 1 of the
present invention. The air-conditioning apparatus 1 will now be
described with reference to FIG. 1. As illustrated in FIG. 1, the
air-conditioning apparatus 1 includes an outdoor unit 2, an indoor
unit 3, and a remote controller 4. The outdoor unit 2, which is
disposed in an outdoor space, includes a compressor 6, a flow
switching device 7, an outdoor heat exchanger 8, an outdoor fan 8a,
an expansion device 9, an outdoor temperature detection device 21,
an outdoor heat-exchanger temperature detection device 22, and an
outdoor control board 30a. The indoor unit 3, which is disposed in
an indoor space, includes an indoor heat exchanger 10, an indoor
fan 10a, an indoor temperature detection unit 23, a human body
detection device 24, and an indoor control board 30b. The
compressor 6, the flow switching device 7, the outdoor heat
exchanger 8, the expansion device 9, and the indoor heat exchanger
10 are connected by pipes, thus forming a refrigerant circuit 5
through which refrigerant flows. The outdoor control board 30a and
the indoor control board 30b are included in a control device
30.
[0019] The compressor 6 compresses the refrigerant. The flow
switching device 7 performs switching between flowing directions of
the refrigerant in the refrigerant circuit 5. To be more specific,
the flow switching device 7 performs the switching to cause the
refrigerant discharged from the compressor 6 to flow to the outdoor
heat exchanger 8 or the indoor heat exchanger 10, thus performing
any of a cooling operation, a heating operation, and a defrosting
operation. The outdoor heat exchanger 8 exchanges heat between the
refrigerant and outdoor air. The outdoor fan 8a sends the outdoor
air to the outdoor heat exchanger 8. The expansion device 9 expands
and decompresses the refrigerant. For example, the expansion device
9 is a solenoid expansion valve whose opening degree is adjusted.
The indoor heat exchanger 10 exchanges heat between the refrigerant
and indoor air. The indoor fan 10a sends the indoor air to the
indoor heat exchanger 10.
[0020] The outdoor temperature detection device 21 detects an
outdoor temperature. The outdoor heat-exchanger temperature
detection device 22 detects the temperature of the outdoor heat
exchanger 8. The indoor temperature detection unit 23 detects an
indoor temperature. The human body detection device 24 detects the
presence or absence of a human body. The outdoor control board 30a
controls components of the outdoor unit 2, and the indoor control
board 30b controls components of the indoor unit 3. The outdoor
control board 30a and the indoor control board 30b are connected by
an interconnecting communication line 30c, through which signals
are transmitted and received between the control boards.
[0021] The remote controller 4 is connected to the indoor control
board 30b by a remote control line 4a, through which the remote
controller 4 transmits and receives signals to/from the indoor
control board 30b. For example, the remote controller 4 transmits a
stop signal to stop an operation of the refrigerant circuit 5 to
the indoor control board 30b, so that the indoor unit 3 and the
outdoor unit 2 stop. In addition, the remote controller 4 transmits
a start signal to start the operation of the refrigerant circuit 5
to the indoor control board 30b, so that the indoor unit 3 and the
outdoor unit 2 start to operate.
[0022] FIG. 2 is a block diagram illustrating the control device 30
of the air-conditioning apparatus 1 according to Embodiment 1 of
the present invention. The control device 30 will now be described.
In Embodiment 1, the control device 30, which is, for example, a
central processing unit (CPU), includes the outdoor control board
30a and the indoor control board 30b as described above. The
control device 30 may be a single control board. In this case, the
control device 30 may be disposed in either one of the outdoor unit
2 and the indoor unit 3. Furthermore, the control device 30 may be
disposed outside the outdoor unit 2 and the indoor unit 3. As
illustrated in FIG. 2, the control device 30 includes a storage
unit 31, a determination unit 32, a changing unit 33, and a
switching unit 34.
[0023] The storage unit 31 stores, for example, an outdoor
heat-exchanger temperature threshold necessary for a requirement
for starting the defrosting operation. The requirement for starting
the defrosting operation is that the temperature of the outdoor
heat exchanger 8 is at or below the outdoor heat-exchanger
temperature threshold in the heating operation in which the outdoor
heat exchanger 8 functions as an evaporator. A prolonged heating
operation results in a reduction in pressure saturation temperature
in the outdoor heat exchanger 8 functioning as an evaporator. When
the pressure saturation temperature in the outdoor heat exchanger 8
is at or below the dew-point temperature of the outdoor air and is
at or below the freezing point of water, frost forms on the outdoor
heat exchanger 8. Upon frost formation on the outdoor heat
exchanger 8, the air-conditioning apparatus 1 performs the
defrosting operation of removing the frost formed on the outdoor
heat exchanger 8, thus reducing worsening of the heat exchange
performance of the outdoor heat exchanger 8 which is caused by such
a frost formation phenomenon. Although the requirement for starting
the defrosting operation in Embodiment 1 is a reduction temperature
of the outdoor heat exchanger 8, the requirement is not limited to
it. For example, the requirement may be a reduction in outdoor
temperature.
[0024] The determination unit 32 determines, based on operation
information about the refrigerant circuit 5, during the heating
operation, whether to change the requirement for starting the
defrosting operation or not. In Embodiment 1, the operation
information is a temperature detected by the outdoor temperature
detection device 21. Specifically, the determination unit 32
determines whether or not the temperature detected by the outdoor
temperature detection device 21 is at or below an outdoor
temperature threshold.
[0025] The changing unit 33 changes the requirement for starting
the defrosting operation in accordance with the result of
determination by the determination unit 32. In Embodiment 1, the
operation information is the temperature detected by the outdoor
temperature detection device 21. Specifically, when the
determination unit 32 determines that the temperature detected by
the outdoor temperature detection device 21 is at or below the
outdoor temperature threshold, the changing unit 33 changes the
requirement for starting the defrosting operation.
[0026] As described above, the requirement for starting the
defrosting operation in Embodiment 1 is that the temperature of the
outdoor heat exchanger 8 is at or below the outdoor heat-exchanger
temperature threshold in the heating operation in which the outdoor
heat exchanger 8 functions as an evaporator. During the heating
operation, the changing unit 33 changes, based on the operation
information regarding the refrigerant circuit 5, the outdoor
heat-exchanger temperature threshold to an outdoor heat-exchanger
temperature relaxed threshold, which is higher than the outdoor
heat-exchanger temperature threshold. Thex1<Thex2 where Thex1 is
the outdoor heat-exchanger temperature threshold, and Thex2 is the
outdoor heat-exchanger temperature relaxed threshold. Consequently,
when the temperature of the outdoor heat exchanger 8 decreases in
the heating operation, it reaches the outdoor heat-exchanger
temperature relaxed threshold Thex2 before reaching the outdoor
heat-exchanger temperature threshold Thex1. That is, the
requirement for starting the defrosting operation based on the
outdoor heat-exchanger temperature relaxed threshold Thex2 is less
strict than that based on the outdoor heat-exchanger temperature
threshold Thex1. When the outdoor heat-exchanger temperature
relaxed threshold Thex2 is applied, the defrosting operation starts
earlier.
[0027] As described above, when it is determined that the
temperature detected by the outdoor temperature detection device 21
is at or below the outdoor temperature threshold, the outdoor
heat-exchanger temperature threshold is changed to the outdoor
heat-exchanger temperature relaxed threshold. Consequently, when
the outdoor temperature is low, it is determined that the outdoor
heat exchanger 8 is highly likely to have been frosted, readily
causing the defrosting operation to be performed.
[0028] The changing unit 33 further has a function of changing the
requirement for starting the defrosting operation in accordance
with the result of detection by the human body detection device 24.
In Embodiment 1, when the human body detection device 24 detects
the absence of a person during the heating operation, the changing
unit 33 changes the outdoor heat-exchanger temperature threshold to
the outdoor heat-exchanger temperature relaxed threshold, which is
higher than the outdoor heat-exchanger temperature threshold.
Consequently, in the absence of a person, it is determined that the
heating operation is highly likely to have been unnecessary,
readily causing the defrosting operation to be performed.
[0029] When the requirement for starting the defrosting operation
stored in the storage unit 31 is satisfied, the switching unit 34
causes the flow switching device 7 to perform switching such that
the defrosting operation is started. The requirement for starting
the defrosting operation is that the temperature of the outdoor
heat exchanger 8 is at or below the outdoor heat-exchanger
temperature threshold in the heating operation in which the outdoor
heat exchanger 8 functions as an evaporator. Where the requirement
for starting the defrosting operation is not changed by the
changing unit 33, the switching unit 34 causes the flow switching
device 7 to perform switching when the temperature of the outdoor
heat exchanger 8 detected by the outdoor heat-exchanger temperature
detection device 22 is at or below the outdoor heat-exchanger
temperature threshold. On the other hand, where the requirement for
starting the defrosting operation is changed by the changing unit
33, the switching unit 34 causes the flow switching device 7 to
perform switching when the temperature of the outdoor heat
exchanger 8 detected by the outdoor heat-exchanger temperature
detection device 22 is at or below the outdoor heat-exchanger
temperature relaxed threshold.
[0030] The control device 30 further performs switching between a
thermo-off state and a thermo-on state. Specifically, the control
device 30 compares an actual indoor temperature U: i degrees C.
with a set temperature V: j degrees C., and determines whether to
continue to operate the outdoor unit 2 and the indoor unit 3 or
not. The actual indoor temperature U is a temperature detected by
the indoor temperature detection unit 23. The set temperature V is
a target indoor temperature set through the remote controller 4 by,
for example, a user. When the actual indoor temperature U is at or
above the set temperature V (i.gtoreq.j) in the heating operation,
the control device 30 including the outdoor control board 30a and
the indoor control board 30b determines that a heating capacity
required by the user is ensured, and performs switching to the
thermo-off state to temporarily stop the operation. At this time,
the stopped indoor unit 3 transmits a thermo-off signal to the
control device 30.
[0031] In the thermo-off state, the control device 30 continues to
operate. When the actual indoor temperature U is below the set
temperature V (i<j) in the thermo-off state, the control device
30 including the outdoor control board 30a and the indoor control
board 30b determines that the heating capacity required by the user
is lacking, and performs switching to the thermo-on state to resume
the operation. At this time, the indoor unit 3 that has resumed the
operation transmits a thermo-on signal to the control device
30.
[0032] Operation modes of the air-conditioning apparatus 1 will now
be described. As the operation modes of the air-conditioning
apparatus 1, a cooling operation, the heating operation, and the
defrosting operation are present. In the cooling operation, the
refrigerant flows through the compressor 6, the flow switching
device 7, the outdoor heat exchanger 8, the expansion device 9, and
the indoor heat exchanger 10 in that order. The refrigerant
exchanges heat with indoor air in the indoor heat exchanger 10,
thus cooling the indoor air. In the heating operation, the
refrigerant flows through the compressor 6, the flow switching
device 7, the indoor heat exchanger 10, the expansion device 9, and
the outdoor heat exchanger 8 in that order. The refrigerant
exchanges heat with indoor air in the indoor heat exchanger 10,
thus heating the indoor air. In the defrosting operation, the
refrigerant flows through the compressor 6, the flow switching
device 7, the outdoor heat exchanger 8, the expansion device 9, and
the indoor heat exchanger 10 in that order, thus removing frost
formed on the outdoor heat exchanger 8.
[0033] An operation of the air-conditioning apparatus 1 in each of
the operation modes will be described below. The cooling operation
will now be described. In the cooling operation, the refrigerant
taken in the compressor 6 is compressed into a high temperature and
high pressure gas refrigerant, and is then discharged from the
compressor 6. The high temperature and high pressure gas
refrigerant discharged from the compressor 6 passes through the
flow switching device 7 and flows into the outdoor heat exchanger
8, in which the refrigerant exchanges heat with the outdoor air
sent by the outdoor fan 8a and is thus condensed and liquefied. The
condensed and liquefied refrigerant flows into the expansion device
9, in which the refrigerant is expanded and decompressed such that
the refrigerant is made to be in a two-phase gas-liquid state. The
refrigerant being in the two-phase gas-liquid state flows into the
indoor heat exchanger 10, in which the refrigerant exchanges heat
with the indoor air and is thus evaporated and gasified. At this
time, the indoor air is cooled, thus performing cooling. The
evaporated and gasified refrigerant passes through the flow
switching device 7 and is taken in the compressor 6.
[0034] The heating operation will now be described. In the heating
operation, the refrigerant taken in the compressor 6 is compressed
into a high temperature and high pressure gas refrigerant, and is
then discharged from the compressor 6. The high temperature and
high pressure gas refrigerant discharged from the compressor 6
passes through the flow switching device 7 and flows into the
indoor heat exchanger 10, in which the refrigerant exchanges heat
with the indoor air sent by the indoor fan 10a and is thus
condensed and liquefied. At this time, the indoor air is heated,
thus performing heating. The condensed and liquefied refrigerant
flows into the expansion device 9, in which the refrigerant is
expanded and decompressed such that the refrigerant is made to be
in a two-phase gas-liquid state. The refrigerant being in the
two-phase gas-liquid state flows into the outdoor heat exchanger 8,
in which the refrigerant exchanges heat with the outdoor air and is
thus evaporated and gasified. The evaporated and gasified
refrigerant passes through the flow switching device 7 and is taken
in the compressor 6.
[0035] The defrosting operation will now be described. In the
heating operation of the air-conditioning apparatus 1, frost may
form on the outdoor heat exchanger 8. The defrosting operation is
performed to remove such frost. In the defrosting operation, the
refrigerant taken in the compressor 6 is compressed into a high
temperature and high pressure gas refrigerant and is then
discharged from the compressor 6. The high temperature and high
pressure gas refrigerant discharged from the compressor 6 passes
through the flow switching device 7 and flows into the outdoor heat
exchanger 8 to melt frost formed on the outdoor heat exchanger 8.
The refrigerant exchanges heat with the outdoor air and is thus
condensed and liquefied in the outdoor heat exchanger 8. The
condensed and liquefied refrigerant flows into the expansion device
9. At this time, the expansion device 9 is fully opened, and the
refrigerant flows into the indoor heat exchanger 10 while kept
liquefied. The refrigerant kept liquefied flows into the indoor
heat exchanger 10, in which the refrigerant exchanges heat with the
indoor air and is thus evaporated and gasified. The evaporated and
gasified refrigerant passes through the flow switching device 7 and
is taken in the compressor 6.
[0036] FIG. 3 is a flowchart illustrating an operation of the
air-conditioning apparatus 1 according to Embodiment 1 of the
present invention. An operation of the control device 30 of the
air-conditioning apparatus 1 according to Embodiment 1 will now be
described. Referring to FIG. 3, upon start of the heating
operation, the determination unit 32 determines whether or not a
temperature detected by the outdoor temperature detection device 21
is at or below the outdoor temperature threshold (step ST1). If the
temperature detected by the outdoor temperature detection device 21
is above the outdoor temperature threshold (No in step ST1), it is
determined whether or not a temperature of the outdoor heat
exchanger 8 detected by the outdoor heat-exchanger temperature
detection device 22 is at or below the outdoor heat-exchanger
temperature threshold (step ST2). If the temperature of the outdoor
heat exchanger 8 is at or below the outdoor heat-exchanger
temperature threshold (Yes in step ST2), the switching unit 34
causes the flow switching device 7 to perform switching to start
the defrosting operation. If the temperature of the outdoor heat
exchanger 8 is above the outdoor heat-exchanger temperature
threshold (No in step ST2), the process returns to step ST1.
[0037] If the temperature detected by the outdoor temperature
detection device 21 is at or below the outdoor temperature
threshold (Yes in step ST1), the human body detection device 24
detects the presence or absence of a human body (step ST3). If the
presence of a person in the indoor space is detected (No in step
ST3), the process proceeds to step ST2. If the absence of a person
is detected (Yes in step ST3), the changing unit 33 changes the
outdoor heat-exchanger temperature threshold to the outdoor
heat-exchanger temperature relaxed threshold, which is higher than
the outdoor heat-exchanger temperature threshold. It is determined
whether or not the temperature of the outdoor heat exchanger 8
detected by the outdoor heat-exchanger temperature detection device
22 is at or below the outdoor heat-exchanger temperature relaxed
threshold (step ST4). If the temperature of the outdoor heat
exchanger 8 is at or below the outdoor heat-exchanger temperature
relaxed threshold (Yes in step ST4), the switching unit 34 causes
the flow switching device 7 to perform switching to start the
defrosting operation. If the temperature of the outdoor heat
exchanger 8 is above the outdoor heat-exchanger temperature relaxed
threshold (No in step ST4), the process returns to step ST1.
[0038] In Embodiment 1, the requirement for starting the defrosting
operation is changed on the basis of the result of determination
based on the operation information. An air-conditioning apparatus
known in the art has a fixed requirement for starting the
defrosting operation. Assuming that the requirement for starting
the defrosting operation is fixed, even when the requirement for
starting the defrosting operation is satisfied, the defrosting
operation would not be performed as long as a person is present in
the indoor space, thus worsening the heat exchange performance of
the outdoor heat exchanger 8. As a result, it would be difficult to
accurately determine whether to perform the defrosting operation or
not. In contrast, according to Embodiment 1, since the requirement
for starting the defrosting operation is changed on the basis of
the result of determination based on the operation information, it
is possible to accurately determine whether to perform the
defrosting operation or not. Furthermore, an air-conditioning
apparatus known in the art determines, only based on the presence
or absence of a person, whether to start the defrosting operation
or not. Then, suppose this air-conditioning apparatus is set such
that the defrosting operation tends to be performed when a person
is absent. In this case, if the outdoor temperature is high, even
when ordinarily, defrosting is unnecessary, the defrosting
operation may frequently be performed, causing a reduction in
indoor temperature. In contrast, according to Embodiment 1, since
the requirement for starting the defrosting operation is changed on
the basis of the result of determination based on the operation
information, this can inhibit an unnecessary defrosting operation,
or idle defrosting, from being frequently performed.
[0039] The air-conditioning apparatus further includes the human
body detection device 24 that detects the presence or absence of a
human body. The changing unit 33 changes the requirement for
starting the defrosting operation in accordance with the result of
determination by the determination unit 32 and the result of
detection by the human body detection device 24. Consequently, when
for example, a person is absent, and the heating capacity is thus
unnecessary, the defrosting operation is actively performed to the
extent that idle defrosting is not frequently performed. In the
presence of a user in the indoor space, therefore, the
comfortability for the user is not lost.
[0040] The air-conditioning apparatus further includes the outdoor
heat-exchanger temperature detection device 22 that detects the
temperature of the outdoor heat exchanger 8. The requirement for
starting the defrosting operation is that a temperature detected by
the outdoor heat-exchanger temperature detection device 22 is at or
below the outdoor heat-exchanger temperature threshold. During the
heating operation, the changing unit 33 changes, based on the
operation information regarding the refrigerant circuit 5, the
outdoor heat-exchanger temperature threshold to the outdoor
heat-exchanger temperature relaxed threshold, which is higher than
the outdoor heat-exchanger temperature threshold. As described
above, it is possible to determine whether or not to perform
defrosting by determining the temperature of the outdoor heat
exchanger 8.
[0041] The air-conditioning apparatus further includes the outdoor
temperature detection device 21 that detects an outdoor
temperature. The operation information is a temperature detected by
the outdoor temperature detection device 21. The determination unit
32 determines whether or not the temperature detected by the
outdoor temperature detection device 21 is at or below the outdoor
temperature threshold. The changing unit 33 changes the requirement
for starting the defrosting operation when the determination unit
32 determines that the temperature detected by the outdoor
temperature detection device 21 is at or below the outdoor
temperature threshold. As described above, it is possible to more
accurately determine whether or not to perform defrosting by
determining the outdoor temperature.
Embodiment 2
[0042] FIG. 4 is a block diagram illustrating a control unit 130 of
an air-conditioning apparatus 100 according to Embodiment 2 of the
present invention. Embodiment 2 differs from Embodiment 1 in that
operation information is an operation frequency of the compressor
6. In Embodiment 2, the same components as those in Embodiment 1
are denoted d by the same reference signs, and an explanation of
these components will be omitted. The following description will be
made mainly by referring to differences between these
Embodiments.
[0043] As illustrated in FIG. 4, the air-conditioning apparatus 100
includes a frequency detection device 125. The frequency detection
device 125 detects an operation frequency of the compressor 6. In
Embodiment 2, the operation information is the operation frequency
detected by the frequency detection device 125. A determination
unit 132 determines whether or not the operation frequency detected
by the frequency detection device 125 is at or above a frequency
threshold. When the operation frequency of the compressor 6 is
high, the amount of heat exchange in the outdoor heat exchanger 8
is increased, and the amount of frost formed on the outdoor heat
exchanger 8 can thus be considered to be increased accordingly.
When the determination unit 132 determines that the operation
frequency detected by the frequency detection device 125 is at or
above the frequency threshold, a changing unit 133 changes the
outdoor heat-exchanger temperature threshold to the outdoor
heat-exchanger temperature relaxed threshold, which is higher than
the outdoor heat-exchanger temperature threshold, so that, as
described above, when the operation frequency of the compressor 6
is high, it is determined that the outdoor heat exchanger 8 is
highly likely to have been frosted, and the defrosting operation is
readily performed.
[0044] The air-conditioning apparatus according to Embodiment 2
further includes the frequency detection device 125 that detects
the operation frequency of the compressor 6. The operation
information is the operation frequency detected by the frequency
detection device 125. The determination unit 132 determines whether
or not the operation frequency detected by the frequency detection
device 125 is at or above the frequency threshold. The changing
unit 133 changes the requirement for starting the defrosting
operation when the determination unit 132 determines that the
operation frequency detected by the frequency detection device 125
is at or above the frequency threshold. The same advantages as
those of Embodiment 1 are achieved in the above-described use of
the operation information indicating the operation frequency of the
compressor 6.
Embodiment 3
[0045] FIG. 5 is a block diagram illustrating a control unit 230 of
an air-conditioning apparatus 200 according to Embodiment 3 of the
present invention. Embodiment 3 differs from Embodiments 1 and 2 in
that operation information is an operation time period of the
defrosting operation. In Embodiment 3, the same components as those
in Embodiments 1 and 2 are denoted by the same reference signs and
an explanation of these components is omitted. The following
description will be made mainly by referring to differences between
Embodiment 3 and Embodiments 1 and 2.
[0046] As illustrated in FIG. 5, the air-conditioning apparatus 200
includes a time measurement device 226. The time measurement device
226 measures the operation time period of the defrosting operation.
In Embodiment 3, the operation information is the operation time
period of the defrosting operation measured by the time measurement
device 226. A determination unit 232 determines whether or not an
operation time period of the preceding defrosting operation
measured by the time measurement device 226 is at or above a time
threshold. If the operation time period of the preceding defrosting
operation is long, it is presumed that the amount of frost formed
on the outdoor heat exchanger 8 is still likely to increase. When
the determination unit 232 determines that the operation time
period of the preceding defrosting operation measured by the time
measurement device 226 is at or above the time threshold, a
changing unit 233 changes the outdoor heat-exchanger temperature
threshold to the outdoor heat-exchanger temperature relaxed
threshold, which is higher than the outdoor heat-exchanger
temperature threshold, so that, as described above, when the
operation time period of the preceding defrosting operation is
long, it is determined that the outdoor heat exchanger 8 is highly
likely to have been frosted and the defrosting operation is readily
performed.
[0047] The air-conditioning apparatus according to Embodiment 3
further includes the time measurement device 226 that measures an
operation time period of the defrosting operation. The operation
information is the operation time period measured by the time
measurement device 226. The determination unit 232 determines
whether or not an operation time period of the preceding defrosting
operation measured by the time measurement device 226 is at or
above the time threshold. When the determination unit 232
determines that the operation time period of the preceding
defrosting operation measured by the time measurement device 226 is
at or above the time threshold, the requirement for starting the
defrosting operation is changed. In such a manner, the operation
information is the operation time of the defrosting operation, and
the same advantages as in Embodiments 1 and 2 are also achieved
using the operation information.
Embodiment 4
[0048] FIG. 6 is a block diagram illustrating a control unit 330 of
an air-conditioning apparatus 300 according to Embodiment 4 of the
present invention. Embodiment 4 differs from Embodiment 1 in that
the control unit 330 includes a signal determination unit 335. In
Embodiment 4, the same components as those in Embodiments 1 to 3
are denoted by the same reference signs and an explanation of these
components is omitted. The following description will be made
mainly by referring to differences between Embodiment 4 and
Embodiments 1 to 3.
[0049] As illustrated in FIG. 6, the control unit 330 includes the
signal determination unit 335. The signal determination unit 335
allows starting the defrosting operation upon receiving a stop
signal from the remote controller 4. The heating operation is
continued unless the signal determination unit 335 receives the
stop signal from the remote controller 4. In Embodiment 4, the
requirement for starting the defrosting operation is changed based
on operation information indicating a temperature detected by the
outdoor temperature detection device 21. The requirement for
starting the defrosting operation is not changed based on the
result of detection by the human body detection device 24.
[0050] In Embodiment 4, after the requirement for starting the
defrosting operation is changed, the defrosting operation is kept
in a standby state even if the changed requirement for starting the
defrosting operation is satisfied. If the signal determination unit
335 has received a stop signal, the standby state of the defrosting
operation is left. The defrosting operation is started before the
operation of the air-conditioning apparatus 300 is stopped. On the
other hand, if the signal determination unit 335 has not received
the stop signal, the standby state of the defrosting operation is
maintained, and the operation of the air-conditioning apparatus 300
is stopped.
[0051] FIG. 7 is a flowchart illustrating an operation of the
air-conditioning apparatus 300 according to Embodiment 4 of the
present invention. An operation of the control unit 330 of the
air-conditioning apparatus 300 according to Embodiment 4 will now
be described. Referring to FIG. 7, upon start of the heating
operation, it is determined whether or not a temperature of the
outdoor heat exchanger 8 detected by the outdoor heat-exchanger
temperature detection device 22 is at or below the outdoor
heat-exchanger temperature threshold (step ST11). If the
temperature of the outdoor heat exchanger 8 is at or below the
outdoor heat-exchanger temperature threshold (Yes in step ST11),
the switching unit 34 causes the flow switching device 7 to perform
switching to start the defrosting operation.
[0052] If the temperature of the outdoor heat exchanger 8 is above
the outdoor heat-exchanger temperature threshold (No in step ST11),
the determination unit 32 determines whether or not a temperature
detected by the outdoor temperature detection device 21 is at or
below the outdoor temperature threshold (step ST12). If the
temperature detected by the outdoor temperature detection device 21
is above the outdoor temperature threshold (No in step ST12), the
signal determination unit 335 determines whether a stop signal has
been received from the remote controller 4 or not (step ST13). If
the stop signal has been received (Yes in step ST13), the operation
of the air-conditioning apparatus 300 is stopped. This is because
the outdoor temperature is high and it is presumed that the outdoor
heat exchanger 8 has not been frosted. If the stop signal has not
been received (No in step ST13), the process returns to step
ST11.
[0053] In step ST12, if the temperature detected by the outdoor
temperature detection device 21 is at or below the outdoor
temperature threshold (Yes in step ST12), the changing unit 33
changes the outdoor heat-exchanger temperature threshold to the
outdoor heat-exchanger temperature relaxed threshold, which is
higher than the outdoor heat-exchanger temperature threshold. It is
determined whether or not the temperature of the outdoor heat
exchanger 8 detected by the outdoor heat-exchanger temperature
detection device 22 is at or below the outdoor heat-exchanger
temperature relaxed threshold (step ST14). If the temperature of
the outdoor heat exchanger 8 is at or below the outdoor
heat-exchanger temperature relaxed threshold (Yes in step ST14),
the signal determination unit 335 determines whether the stop
signal has been received from the remote controller 4 or not (step
ST15). If the stop signal has been received (Yes in step ST15), the
switching unit 34 causes the flow switching device 7 to perform
switching to start the defrosting operation. After that, the
operation of the air-conditioning apparatus 300 is stopped. If the
stop signal has not been received (No in step ST15), the process
returns to step ST11. This is because the outdoor temperature is
low and it is presumed that the outdoor heat exchanger 8 is likely
to have been frosted.
[0054] If the temperature of the outdoor heat exchanger 8 is above
the outdoor heat-exchanger temperature relaxed threshold (No in
step ST14), the signal determination unit 335 determines whether
the stop signal has been received from the remote controller 4 or
not (step ST16). If the stop signal has been received (Yes in step
ST16), the operation of the air-conditioning apparatus 300 is
stopped. If the stop signal has not been received (No in step
ST16), the process returns to step ST11 for the following reason:
although because of a low outdoor temperature, it is presumed that
the outdoor heat exchanger 8 is likely to have been frosted, the
stop signal has not been received and it is presumed that the user
requires the heating operation.
[0055] The air-conditioning apparatus according to Embodiment 4
further includes the remote controller 4 that transmits a stop
signal to stop the operation of the refrigerant circuit 5. The
control unit 330 further includes the signal determination unit 335
that allows starting the defrosting operation upon receiving the
stop signal from the remote controller 4. The switching unit 34
causes, when the signal determination unit 335 allows starting the
defrosting operation, the flow switching device 7 to perform
switching to start the defrosting operation. Consequently, when the
user does not require the heating operation, the defrosting
operation is actively performed, so that the heating capacity to be
used when the heating operation is again required can be saved.
Therefore, Embodiment 4 can obtain an advantage in which the
comfortability for the user can be improved, in addition to the
advantages obtained in Embodiment 1.
[0056] In Embodiment 4, the requirement for starting the defrosting
operation may be changed based not only on operation information
but on the result of detection result by the human body detection
device 24 as in Embodiment 1. Furthermore, in Embodiment 4, the
operation information may be the operation frequency of the
compressor 6 as in Embodiment 2 or may be the operation time period
of the defrosting operation as in Embodiment 3.
Embodiment 5
[0057] FIG. 8 is a block diagram illustrating a control unit 430 of
an air-conditioning apparatus 400 according to Embodiment 5 of the
present invention. Embodiment 5 differs from Embodiment 4 in that a
signal determination unit 435 determines whether to allow the
defrosting operation in response to determining whether a
thermo-off signal has been received or not. In Embodiment 5, the
same components as those in Embodiments 1 to 4 are denoted by the
same reference signs and an explanation of these components will be
omitted. The following description will be made mainly by referring
to differences between Embodiment 5 and Embodiments 1 to 4.
[0058] As illustrated in FIG. 8, the control unit 430 includes the
signal determination unit 435. The signal determination unit 435
allows starting the defrosting operation upon receiving a
thermo-off signal from the indoor unit 3. The heating operation is
continued unless the signal determination unit 435 receives the
thermo-off signal. In Embodiment 5, the requirement for starting
the defrosting operation is changed based on operation information
indicating a temperature detected by the outdoor temperature
detection device 21. The requirement for starting the defrosting
operation in Embodiment 5 is not changed based on the result of
detection by the human body detection device 24.
[0059] In Embodiment 5, after the requirement for starting the
defrosting operation is changed, the defrosting operation is kept
in the standby state even if the changed requirement for starting
the defrosting operation is satisfied. If the signal determination
unit 435 has received a thermo-off signal, the standby state of the
defrosting operation is left. The defrosting operation is started
before the operation of the air-conditioning apparatus 400 is
stopped. If the signal determination unit 435 has not received the
thermo-off signal, the standby state of the defrosting operation is
maintained and the operation of the air-conditioning apparatus 400
is stopped.
[0060] FIG. 9 is a flowchart of an operation of the
air-conditioning apparatus 400 according to Embodiment 5 of the
present invention. An operation of the control unit 430 of the
air-conditioning apparatus 400 according to Embodiment 5 will now
be described. Referring to FIG. 9, upon start of the heating
operation, it is determined whether or not a temperature of the
outdoor heat exchanger 8 detected by the outdoor heat-exchanger
temperature detection device 22 is at or below the outdoor
heat-exchanger temperature threshold (step ST21). If the
temperature of the outdoor heat exchanger 8 is at or below the
outdoor heat-exchanger temperature threshold (Yes in step ST21),
the switching unit 34 causes the flow switching device 7 to start
the defrosting operation.
[0061] If the temperature of the outdoor heat exchanger 8 is above
the outdoor heat-exchanger temperature threshold (No in step ST21),
the determination unit 32 determines whether or not a temperature
detected by the outdoor temperature detection device 21 is at or
below the outdoor temperature threshold (step ST22). If the
temperature detected by the outdoor temperature detection device 21
is above the outdoor temperature threshold (No in step ST22), the
signal determination unit 435 determines whether a thermo-off
signal has been received from the indoor unit 3 or not (step ST23).
If the thermo-off signal has been received (Yes in step ST23), the
operation of the outdoor unit 2 and that of the indoor unit 3 are
stopped. This is because the outdoor temperature is high and it is
presumed that the outdoor heat exchanger 8 is free from frost. If
the thermo-off signal has not been received (No in step ST23), the
process returns to step ST21.
[0062] In step ST22, if the temperature detected by the outdoor
temperature detection device 21 is at or below the outdoor
temperature threshold (Yes in step ST22), the changing unit 33
changes the outdoor heat-exchanger temperature threshold to the
outdoor heat-exchanger temperature relaxed threshold, which is
higher than the outdoor heat-exchanger temperature threshold. It is
determined whether or not the temperature of the outdoor heat
exchanger 8 detected by the outdoor heat-exchanger temperature
detection device 22 is at or below the outdoor heat-exchanger
temperature relaxed threshold (step ST24). If the temperature of
the outdoor heat exchanger 8 is at or below the outdoor
heat-exchanger temperature relaxed threshold (Yes in step ST24),
the signal determination unit 435 determines whether the thermo-off
signal has been received from the indoor unit 3 (step ST25). If the
thermo-off signal has been received (Yes in step ST25), the
switching unit 34 causes the flow switching device 7 to start the
defrosting operation. After that, the operation of the outdoor unit
2 and that of the indoor unit 3 are stopped. If the thermo-off
signal has not been received (No in step ST25), the process returns
to step ST21. This is because the outdoor temperature is low and it
is presumed that the outdoor heat exchanger 8 is likely to have
been frosted.
[0063] If the temperature of the outdoor heat exchanger 8 is above
the outdoor heat-exchanger temperature relaxed threshold (No in
step ST24), the signal determination unit 435 determines whether
the thermo-off signal has been received from the indoor unit 3
(step ST26). If the thermo-off signal has been received (Yes in
step ST26), the operation of the outdoor unit 2 and that of the
indoor unit 3 are stopped. If the thermo-off signal has not been
received (No in step ST26), the process returns to step ST21 for
the following reason: although because of a low outdoor
temperature, it is presumed that the outdoor heat exchanger 8 is
likely to have been frosted, the thermo-off signal has not been
received and it is presumed that the heating operation is still
required.
[0064] In Embodiment 5, the control unit 430 further includes the
signal determination unit 435 that allows starting the defrosting
operation upon receiving a thermo-off signal indicating the
thermo-off state, in which the heating operation is temporarily
stopped when the actual indoor temperature is above a set
temperature. When the signal determination unit 435 allows starting
the defrosting operation, the switching unit 34 causes the flow
switching device 7 to switch to start the defrosting operation.
Consequently, when the heating operation is unnecessary, the
defrosting operation is actively performed, so that the heating
capacity to be used when the heating operation is resumed in
response to switching to the thermo-on state can be saved.
Therefore, Embodiment 5 can obtain an advantage in which the
comfortability for the user can be improved, in addition to the
advantages obtained in Embodiment 1.
[0065] In Embodiment 5, the requirement for starting the defrosting
operation may be changed based not only on operation information
but on the result of detection by the human body detection device
24 as in Embodiment 1. Furthermore, in Embodiment 5, the operation
information may be the operation frequency of the compressor 6 as
in Embodiment 2 or may be the operation time period of the
defrosting operation as in Embodiment 3.
[0066] REFERENCE SIGNS LIST
[0067] 1 air-conditioning apparatus 2 outdoor unit 3 indoor unit 4
remote controller 4a remote control line 5 refrigerant circuit 6
compressor 7 flow switching device 8 outdoor heat exchanger 8a
outdoor fan 9 expansion device 10 indoor heat exchanger 10a indoor
fan 21 outdoor temperature detection device 22 outdoor
heat-exchanger temperature detection device 23 indoor temperature
detection unit 24 human body detection device 30 control 30a
outdoor control board 30b indoor control board 30c interconnecting
communication line 31 storage unit 32 determination unit 33
changing unit 34 switching unit 100 air-conditioning apparatus 125
frequency detection device 130 control unit 132 determination unit
133 changing unit 200 air-conditioning apparatus 226 time
measurement device 230 control unit 232 determination unit 233
changing unit 300 air-conditioning apparatus 330 control unit 335
signal determination unit 400 air-conditioning apparatus 430
control unit 435 signal determination unit
* * * * *