Technical Field
[0001] The present invention relates to an air-conditioning apparatus which circulates refrigerant
to perform air conditioning.
Background Art
[0002] While an operation of an air-conditioning apparatus is stopped, there is a case where
refrigerant accumulates in a compressor. When the air-conditioning apparatus is started,
with the refrigerant accumulating in the compressor, the compressor may be damaged.
In view of this point, a related-art air-conditioning apparatus performs compressor
protection control for preventing a compressor from being damaged at the time of starting
the air-conditioning apparatus (see, for example, Patent Literature 1). Patent Literature
2 is concerned with providing an air conditioner having a crankcase heater in which
a compressor can be controlled to start by using an existing temperature sensor to
determine whether it is a return from a temporary de-energized state due to power
failure or the like on the basis of a detection temperature of the temperature sensor.
[0003] Patent Literature 3 discloses an air-conditioning apparatus according to the preambles
of claims 1 and 2.
[0004] It should be noted that the compressor protection control is a control that when
the compressor is in a stopped state, a heating unit such as a heater heats the compressor
to evaporate refrigerant accumulating in the compressor. The air-conditioning apparatus
of Patent Literature 1 performs the compressor protection control by supplying power
to an electric heater wound around the compressor.
[0005] Furthermore, in another related-art air-conditioning apparatus, an operation frequency
is restricted for a while after the apparatus is started, and the compressor protection
control is performed with heat generated by a coil of an electric motor included in
a compressor, in consideration of the case where supplying of power may be stopped
for a long period of time, and heating could not be performed using a heating unit
such as a heater.
Citation List
Patent Literature
[0006]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2010-112619
Patent Literature 2: Japanese Patent Application Publication No. 2013-145092 A
Patent Literature 3: Japanese Patent Application Publication JPH109687A.
Summary of Invention
Technical Problem
[0007] However, in general, it takes several hours that refrigerant accumulates in the compressor
after an operation of an air-conditioning apparatus is stopped, and thus the compressor
protection control does not need to be performed, for example, in the case where supplying
of power is restated after a short time elapses from occurrence of a power failure.
However, the related-art air-conditioning apparatus necessarily executes the compressor
protection control when it is started, regardless of whether a power failure continues
for a short time or supplying of power is stopped for a long time. The compressor
cannot be operated at 100% of capacity while the compressor protection control is
being performed. Therefore, in the related-art air-conditioning apparatus, even if
the time for which a power failure continues is short, it takes long time to restore
the state of air in a to-be-air-conditioned space to that prior to occurrence of the
power failure.
[0008] The present invention has been made to solve the above problem, and an object of
the invention is to provide an air-conditioning apparatus capable of rapidly restoring
the state of air in a to-be-air-conditioned space to that prior to occurrence of a
power failure in the case where supplying of power is restarted after elapses of a
short time from occurrence of the power failure.
Solution to Problem
[0009] An air-conditioning apparatus according to the present invention is described in
independent claim 1 and independent claim 2.
Advantageous Effects of Invention
[0010] According to one embodiment of the present invention, when the difference between
a temperature which is detected as temperature information when a power failure occurs
and a temperature which is detected as temperature information when a power recovery
is made is smaller than or equal to a power-failure reference threshold value, a compressor
is rotationally driven to proceed to a normal operation control without performing
a compressor protection control. Thus, the compressor can be rapidly caused to operate
at the capacity at which the compressor was operated before occurence of the power
failure. Accordingly, in the case where supplying of power is restarted after a short
time elapses from occurence of the power failure, the state of air in a to-be-air-conditioned
space can be rapidly restored to the air-conditioned state thereof prior to occurrence
of the power failure.
Brief Description of Drawings
[0011]
[Fig. 1] Fig. 1 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to the first example not according to the invention.
[Fig. 2] Fig. 2 is a block diagram illustrating a functional configuration of an outdoor-unit
control device as illustrated in Fig. 1.
[Fig. 3] Fig. 3 is a flowchart illustrating an operation of the air-conditioning apparatus
as illustrated in Fig. 1.
[Fig. 4] Fig. 4 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to the first embodiment of the present invention.
[Fig. 5] Fig. 5 is a block diagram illustrating a functional configuration of an outdoor-unit
control device as illustrated in Fig. 4.
[Fig. 6] Fig. 6 is a flowchart illustrating an operation of the air-conditioning apparatus
as illustrated in Fig. 4.
[Fig. 7] Fig. 7 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to the second example not according to the invention.
[Fig. 8] Fig. 8 is a block diagram illustrating a functional configuration of an outdoor-unit
control device as illustrated in Fig. 7.
[Fig. 9] Fig. 9 is a flowchart illustrating an operation of the air-conditioning apparatus
as illustrated in Fig. 7.
Description of embodiments
First example
[0012] Fig. 1 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to an first example not according to the invention. The configuration
of an air-conditioning apparatus 100 will be overall described with reference to Fig.
1. As illustrated in Fig. 1, the air-conditioning apparatus 100 includes an outdoor
unit 1 and an indoor unit 2. The outdoor unit 1 and the indoor unit 2 are operated
by power supplied from a commercial power supply 500 which is an AC power supply.
[0013] The outdoor unit 1 includes a compressor 3, a heat-source-side heat exchanger 4,
a heat-source-side fan 7, and an outdoor-unit control device 9. The indoor unit 2
includes an expansion valve 5, a load-side heat exchanger 6, a load-side fan 8, and
an indoor-unit control device 10. The compressor 3, the heat-source-side heat exchanger
4, the expansion valve 5, and the load-side heat exchanger 6 are coupled to each other
by a refrigerant pipe 13 to form a refrigerant circuit which circulates refrigerant.
[0014] The compressor 3 is a compressor whose capacity is variable, and is provided to compress
the refrigerant. The compressor 3 includes a compressor motor (not shown) to be controlled
by an inverter. The heat-source-side heat exchanger 4 is formed of, for example, a
fin-and-tube heat exchanger, and causes heat exchange to be performed between the
refrigerant and outside air which is a heat medium. The expansion valve 5 is formed
of, for example, an electronic expansion valve, and reduces the pressure of the refrigerant.
The load-side heat exchanger 6 is formed of, for example, a fin-and-tube heat exchanger,
and causes heat exchange to be performed between the refrigerant and air in a to-be-air-conditioned
space.
[0015] The heat-source-side fan 7 is formed of an axial flow fan such as a propeller fan,
and is provided for the heat-source-side heat exchanger 4. The heat-source-side fan
7 sends air to the heat-source-side heat exchanger 4. The load-side fan 8 is formed
of a centrifugal fan such as a cross-flow fan, and is provided for the load-side heat
exchanger 6. The load-side fan 8 sends air to the load-side heat exchanger 6.
[0016] The outdoor unit 1 includes a discharge temperature detection device 3a provided
on a discharge side of the compressor 3 to detect a discharge temperature, which is
the temperature of refrigerant discharged from the compressor 3. The discharge temperature
detection device 3a is, for example, a temperature sensor formed of a thermistor,
and is provided at, for example, a discharge port of the compressor 3.
[0017] The indoor unit 2 includes a suction temperature detection device 11 and an input
device 12. The suction temperature detection device 11 is, for example, a temperature
sensor formed of a thermistor, and is provided to detect an indoor air temperature,
which is the temperature of air in the to-be-air-conditioned space. The input device
12 is to be operated by a user. That is, the input device 12 allows the user to, for
example, turn on/off a power source, set a target temperature, set the direction of
wind, and set the velocity of wind.
[0018] The outdoor-unit control device 9 controls operations of various actuators provided
in the outdoor unit 1, such as the compressor 3 and the heat-source-side fan 7. The
indoor-unit control device 10 controls operations of various actuators provided in
the indoor unit 1, such as the expansion valve 5 and the load-side fan 8. The outdoor-unit
control device 9 and the indoor-unit control device 10 mutually communicate with each
other to execute cooperative control of the air-conditioning apparatus 100. That is,
the outdoor-unit control device 9 can control the operations of various actuators
provided in the indoor unit 2, using the indoor-unit control device 10.
[0019] Fig. 2 is a block diagram illustrating a functional configuration of the outdoor-unit
control device 9 as illustrated in Fig. 1. As illustrated in Fig. 2, the outdoor-unit
control device 9 includes a power-failure detection unit 91, a temperature storage
processing unit 92, a storage unit 93, a temperature difference calculation unit 94
and an operation control unit 95.
[0020] The power-failure detection unit 91 constantly monitors the state of supplying of
power from the commercial power supply 500 to detect a stop of supplying of power
from the commercial power supply 500, that is, a power failure. Also, the power-failure
detection unit 91 detects that supplying of the power from the commercial power supply
500 is restarted, that is, a power recovery, and outputs a signal indicating detection
of the power recovery to the temperature storage processing unit 92.
[0021] The temperature storage processing unit 92 acquires, when the power-failure detection
unit 91 detects a power failure, information indicating a discharge temperature from
the discharge temperature detection device 3a, and stores the acquired information
indicating the discharge temperature in the storage unit 93 as a discharge temperature
Td
off. Also, the temperature storage processing unit 92 acquires, when receiving the signal
indicating detection of the power recovery from the power-failure detection unit 91,
information indicating the discharge temperature from the discharge temperature detection
device 3a, and stores the acquired information indicating the discharge temperature
in the storage unit 93 as a discharge temperature Td
on.
[0022] The storage unit 93 stores, as described above, the discharge temperature Td
off and the discharge temperature Td
on which are temperature information. The storage unit 93 can hold the stored information
even during the power failure. It should be noted that the storage unit 93 can be
formed of a programmable read only memory (PROM) such as a flash memory or a hard
disk drive (HDD).
[0023] The temperature difference calculation unit 94 finds out a difference between the
discharge temperature Td
on which is detected by the discharge temperature detection device 3a when a power recovery
is made from a power failure state and the discharge temperature Td
off which is detected by the discharge temperature detection device 3a when the power-failure
detection unit 91 detects the power failure. To be more specific, the temperature
difference calculation unit 94 reads out the discharge temperature Td
off and the discharge temperature Td
on from the storage unit 93 when supplying of power from the commercial power supply
500 is restarted after occurrence of the power failure, and calculates a temperature
difference ΔTd by subtracting the discharge temperature Td
on from the discharge temperature Td
off. Also, the temperature difference calculation unit 94 has a function of outputting
the calculated temperature difference ΔTd to the operation control unit 95.
[0024] The operation control unit 95 includes a power-failure time determination unit 95a,
a protection control unit 95b and an air-conditioning control unit 95c. The power-failure
time determination unit 95a compares the temperature difference ΔTd calculated by
the temperature difference calculation unit 94 with a power-failure reference threshold
value to determine whether or not the temperature difference ΔTd is greater than the
power-failure reference threshold value.
[0025] Incidentally, in the air-conditioning apparatus 100, the discharge temperature of
the compressor 3 is important operation data for recognizing the operation state thereof.
Therefore, the discharge temperature detection device 3a is covered with a heat insulating
material (not shown). When the air-conditioning apparatus 100 is in operation, the
discharge temperature of the compressor 3 is higher than the temperature of outside
air by approximately ten degrees C to several tens of degrees C. When the operation
of the air-conditioning apparatus 100 is stopped, the discharge temperature detected
by the discharge temperature detection device 3a gradually approaches the temperature
of the outside air.
[0026] In this case, as a situation in which the variation of the discharge temperature
of the compressor 3 is the minimum, for example, the following situation is conceivable:
when the air-conditioning apparatus 100 is in operation, the difference between the
discharge temperature of the compressor 3 and the temperature of outside air is only
approximately 10 degrees C. Under this situation, the discharge temperature of the
compressor 3 varies only by approximately 10 degrees C from the time when a power
failure occurs to the time when a power recovery is made.
[0027] In view of the above circumstances, in the first example, the power-failure reference
threshold value is set to 10 degrees C. It should be noted that the time required
until the discharge temperature of the compressor 3 lowers by 10 degrees C is several
minutes to several tens of minutes, but the time required until refrigerant accumulates
in the compressor 3 is generally several hours. Therefore, the refrigerant does not
accumulate in the compressor 3 before the discharge temperature of the compressor
3 lowers by 10 degrees C. Thus, in the case where the temperature difference ΔTd is
10 degrees C or smaller, the compressor 3 will not be damaged even if the compressor
protection control is not performed.
[0028] The power-failure reference threshold value may be varied as appropriate in accordance
with, for example, the amount of refrigerant in the air-conditioning apparatus 100,
the type of the compressor 3, and the state of attachment of the discharge temperature
detection device 3a or the suction temperature detection device 11. For example, the
power-failure reference threshold value may be set to a value smaller than 10 degrees
C. That is, in the case where the power-failure reference threshold value is set in
accordance with, for example, the amount of refrigerant in the air-conditioning apparatus
100, and the temperature difference ΔTd is smaller than or equal to the power-failure
reference threshold value, the compressor 3 can be prevented from being damaged, even
without the compressor protection control.
[0029] Therefore, when the temperature difference ΔTd is greater than the power-failure
reference threshold value, the power-failure time determination unit 95a can determine
that a power failure time is long, and thus outputs a control command signal to the
protection control unit 95b to request the protection control unit 95b to perform
the compressor protection control. By contrast, when the temperature difference ΔTd
is smaller than or equal to the power-failure reference threshold value, the power-failure
time determination unit 95a can determine that the power-failure time is short, and
thus outputs a control command signal to the air-conditioning control unit 95c to
request the protection control unit 95b to omit the compressor protection control.
It should be noted that the power-failure time is time required from occurrence of
occurrence of the power failure to restarting of supplying of power.
[0030] The protection control unit 95b performs a compressor protection control of heating
the compressor 3 only for a fixed period of time in response to the control command
signal from the power-failure time determination unit 95a. In the first embodiment,
the compressor 3 includes an electric heater (not shown), and the protection control
unit 95b energizes the electric heater for a fixed period of time in response to the
control command signal from the power-failure time determination unit 95a. Furthermore,
the protection control unit 95b outputs the control command signal to the air-conditioning
control unit 95c when the compressor protection control is ended, that is, when the
fixed period of time elapses.
[0031] In response to the control command signal output from the power-failure time determination
unit 95a or the protection control unit 95b, the air-conditioning control unit 95c
rotationally drives the compressor 3, and performs a normal operation control associated
with air conditioning. In the following, the normal operation control associated with
air conditioning is also referred to as "normal operation control".
[0032] To be more specific, the air-conditioning control unit 95c performs the normal operation
control in cooperation with the indoor-unit control device 10 by controlling the operations
of the various actuators provided in the outdoor unit 1 and the indoor unit 2. For
example, the air-conditioning control unit 95c controls the operations of the various
actuators in accordance with settings made using the input device 12 or the like.
Also, the air-conditioning control unit 95c controls the operations of the various
actuators in such a way as to reduce the difference between a target temperature set
using the input device 12 and an indoor-air temperature detected by the suction temperature
detection device 11.
[0033] That is, in the case where the temperature difference ΔTd is greater than the power-failure
reference threshold value, the operation control unit 95 performs the compressor protection
control, and then rotationally drives the compressor 3 to execute the normal operation
control. By contrast, in the case where the temperature difference ΔTd is smaller
than or equal to the power-failure reference threshold value, the operation control
unit 95 rotationally drives the compressor 3 to execute the normal operation control
without performing the compressor protection control.
[0034] As described above, when supplying of power is restarted, the outdoor-unit control
device 9 indirectly determines whether or not the power-failure time is short, based
on the discharge temperature detected by the discharge temperature detection device
3a, and performs protection necessity determination processing of determining whether
or not to perform the compressor protection control before performing the normal operation
control.
[0035] Although the first example is described above by referring to by way of example the
case where the power-failure detection unit 91 has a function of detecting a power
recovery, this is an example, and is not limitative. The temperature storage processing
unit 92 may be made to have a function of detecting a power recovery. Furthermore,
the temperature difference calculation unit 94 may store the temperature difference
ΔTd in the storage unit 93 or the like instead of outputting the temperature difference
ΔTd to the operation control unit 95. In this case, the power-failure time determination
unit 95a may read out the temperature difference ΔTd from the storage unit 93 or the
like, and perform determination processing.
[0036] In this case, the outdoor-unit control device 9 and the indoor-unit control device
10 can be made of hardware such as a circuit device which fulfills the above functions,
or can be made of software to be executed on a microcomputer such as digital signal
processor (DSP) or an arithmetic unit such as a central processing unit (CPU).
[0037] Fig. 3 is a flowchart illustrating the operation of the air-conditioning apparatus
100 as illustrated in Fig. 1. With reference to Fig. 3, the following description
is made by referring to a control operation by the outdoor-unit control device 9,
mainly to the protection necessity determination processing.
[0038] First, the temperature storage processing unit 92 is on standby until the power-failure
detection unit 91 detects a power failure (NO in step S101 in Fig. 3). When the power-failure
detection unit 91 detects the power failure (YES in step S101 in Fig. 3), the temperature
storage processing unit 92 stores the discharge temperature Td
off detected by the discharge temperature detection device 3a in the storage unit 93
(Step S102 in Fig. 3). The operation of the air-conditioning apparatus 100 is in a
stopped state until supplying of power from the commercial power supply 500 is restarted
(NO in step S103 in Fig. 3).
[0039] When supplying of power from the commercial power supply 500 is restarted (YES in
step 103 in Fig. 3), the temperature storage processing unit 92 stores the discharge
temperature Td
on detected by the discharge temperature detection device 3a in the storage unit 93
(step S104 in Fig. 3).
[0040] Next, the temperature difference calculation unit 94 reads out the discharge temperature
Td
off and the discharge temperature Td
on stored in the storage unit 93, and calculates the temperature difference ΔTd by subtracting
the discharge temperature Td
on from the discharge temperature Td
off (step S105 in Fig. 3).
[0041] The operation control unit 95 compares the temperature difference ΔTd calculated
by the temperature difference calculation unit 94 with the power-failure reference
threshold value to determine whether or not the temperature difference ΔTd is greater
than the power-failure reference threshold value (step S106 in Fig. 3). When the temperature
difference ΔTd is greater than the power-failure reference threshold value (YES in
step S106 in Fig. 3), the operation control unit 95 executes the compressor protection
control (step S107 in Fig. 3), and then rotationally drives the compressor 3 to execute
the normal operation control (step S108 in Fig. 3). By contrast, when the temperature
difference ΔTd is smaller than or equal to the power-failure reference threshold value
(NO in step S106 in Fig. 3), the operation control unit 95 rotationally drives the
compressor 3 to execute the normal operation control without executing the compressor
protection control (step S108 in Fig. 3).
[0042] As described above, in the air-conditioning apparatus 100 according to the first
example, when a power failure occurs, the power-failure detection unit 91 detects
the power failure, and stores the discharge temperature Td
off in the storage unit 93. Then, when supplying of power is restarted after occurrence
of the power failure, the air-conditioning apparatus 100 automatically restarts its
operation. At this time, the air-conditioning apparatus 100 compares the discharge
temperature Td
on obtained after restarting of supplying of power, with the discharge temperature Td
off to determines whether or not to execute the compressor protection control, based
on the result of the comparison.
[0043] To be more specific, when the temperature difference ΔTd between the discharge temperature
Td
on and the discharge temperature Td
off is smaller than or equal to the power-failure reference threshold value, the air-conditioning
apparatus 100 omits the compressor protection control, and returns to the normal operation
control which was executed before the power failure. On the other hand, when the temperature
difference ΔTd is greater than the power-failure reference threshold value, the air-conditioning
apparatus 100 executes the compressor protection control, and after the compressor
protection control is ended, returns to the normal operation control which was before
occurrence of the power failure. That is, when supplying of power is restarted after
elapse of a short time from occurrence of the power failure, the air-conditioning
apparatus 100 can omit the compressor protection control, which is unnecessary in
this case, and can thus rapidly causes the compressor 3 to be operated at the capacity
at which the compressor 3 was operated before occurrence of the power failure, and
can also rapidly restore the state of the air in the to-be-air-conditioned space to
the air-conditioned state thereof prior to occurrence of the power failure.
[0044] Further, since the time required until the discharge temperature of the compressor
3 lowers by the power-failure reference threshold value is shorter than the time required
until refrigerant accumulates in the compressor 3, the refrigerant does not accumulate
in the compressor 3 within the time required until the discharge temperature of the
compressor 3 lowers by the power-failure reference threshold value. Therefore, in
the case where the temperature difference ΔTd is smaller than or equal to the power-failure
reference threshold value, the air-conditioning apparatus 100 can omit the compressor
protection control without damaging the compressor 3.
[0045] Therefore, in the air-conditioning apparatus 100, even if a condition during the
power failure, for example, the temperature of air during the power failure, changes,
it can be rapidly adjusted, and the state of air in the to-be-air-conditioned space
can be rapidly restored to the air-conditioned state thereof prior to the power failure.
Thus, the reliability is ensured.
First embodiment
[0046] Fig. 4 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to the first embodiment of the present invention. A configuration
of an air-conditioning apparatus 100A will be overall described with reference to
Fig. 4. Components which are the same as or similar to those of the air-conditioning
apparatus 100 according to the first example described above will be denoted by the
same reference signs, and their descriptions will be omitted.
[0047] The outdoor unit 1 of the air-conditioning apparatus 100A includes an inverter device
14, a heat-transfer fin 14a, a first inverter device 15, a first heat-transfer fin
15a and a heat-transfer temperature detection device 17. The inverter device 14 and
the outdoor unit 1 drive a compressor motor of the compressor 3 in response to a control
signal from the outdoor-unit control device 9A. The inverter device 14 produces a
voltage for operating the compressor 3, and supplies the produced voltage to the compressor
motor.
[0048] The heat-transfer fin 14a transfers heat generated in the inverter device 14. The
heat-transfer fin 14a is formed of, for example, a heatsink, and is provided in the
inverter device 14. The heat-transfer fin 14a transfers heat, especially heat generated
by a switching element (not shown) included in the inverter device 14.
[0049] The heat-transfer temperature detection device 17 is, for example, a temperature
sensor formed of a thermistor, and is provided in the heat-transfer fin 14a. The heat-transfer
temperature detection device 17 detects a heat-transfer temperature, which is the
temperature of the heat-transfer fin 14a provided in the inverter device 14. The heat-transfer
temperature is included in the "temperature information" in the present invention.
[0050] The first inverter device 15 drives a motor included in the heat-source-side fan
7 in response to a control signal from the outdoor-unit control device 9A. The first
heat-transfer fin 15a is formed of, for example, a heatsink, and transfers heat generated
in the first inverter device 15.
[0051] The first inverter device 15 corresponds to the "inverter circuit" in the present
invention, and the first heat-transfer fin 15a corresponds to the "heat-transfer fin"
in the present invention.
[0052] The indoor unit 2 of the air-conditioning apparatus 100A includes a second inverter
device 16 and a second heat-transfer fin 16a. The second inverter device 16 drives
a motor included in the load-side fan 8 in response to a control signal from the indoor-unit
control device 10A. The second heat-transfer fin 16a is formed of, for example, a
heatsink, and transfers heat generated in the second inverter device 16.
[0053] The second inverter device 16 corresponds to the "inverter circuit" in the present
invention, and the second heat-transfer fin 16a corresponds to the "heat-transfer
fin" in the present invention.
[0054] The outdoor-unit control device 9A has a function of controlling the operations of
the inverter device 14 and the first inverter device 15. The indoor-unit control device
10A has a function of controlling the operation of the second inverter device 16.
The other configurations of the outdoor-unit control device 9A and the indoor-unit
control device 10A are the same as those of the outdoor-unit control device 9 and
the indoor-unit control device 10 in the first embodiment.
[0055] Fig. 5 is a block diagram illustrating a functional configuration of the outdoor-unit
control device 9A as illustrated in Fig. 4. The outdoor-unit control device 9A includes
a temperature storage processing unit 192, a temperature difference calculation unit
194, and an operation control unit 195 including a power-failure time determination
unit 195a.
[0056] The temperature storage processing unit 192 acquires, when the power-failure detection
unit 91 detects a power failure, information indicating the heat-transfer temperature
from the heat-transfer temperature detection device 17, and stores the acquired information
indicating the heat-transfer temperature in the storage unit 93 as a heat-transfer
temperature Tinv
off. Furthermore, the temperature storage processing unit 192 acquires, when a power
recovery is made from the power failure state, information indicating the heat-transfer
temperature from the heat-transfer temperature detection device 17, and stores the
acquired information indicating the heat-transfer temperature in the storage unit
93 as a heat-transfer temperature Tinv
on. That is, in the second embodiment, the storage unit 93 stores the heat-transfer
temperature Tinv
off and the heat-transfer temperature Tinv
on as temperature information. The other configuration of the temperature storage processing
unit 192 is the same as that of the temperature storage processing unit 92 in the
first example.
[0057] The temperature difference calculation unit 194 calculates a difference between the
heat-transfer temperature which is detected by the heat-transfer temperature detection
device 17 when the power recovery is made from the power failure state and the heat-transfer
temperature which is detected by the heat-transfer temperature detection device 17
when the power-failure detection unit 91 detects the power failure. To be more specific,
the temperature difference calculation unit 194 reads out the heat-transfer temperature
Tinv
off and the heat-transfer temperature Tinv
on from the storage unit 93 when supplying of power from the commercial power supply
500 is restarted after occurrence of the power failure, and calculates a temperature
difference ΔTinv by subtracting the heat-transfer temperature Tinv
on from the heat-transfer temperature Tinv
off. Furthermore, the temperature difference calculation unit 194 has a function of outputting
the calculated temperature difference ΔTinv to the operation control unit 195.
[0058] The power-failure time determination unit 195a compares the temperature difference
ΔTinv calculated by the temperature difference calculation unit 194 with a power-failure
reference threshold value to determine whether or not the temperature difference ΔTinv
is greater that the power-failure reference threshold value. When the temperature
difference ΔTinv is greater than the power-failure reference threshold value, the
power-failure determination unit 195a can determine that the power-failure time is
long, and the power-failure time determination unit 195a thus outputs a control command
signal to the protection control unit 95b. By contrast, when the temperature difference
ΔTinv is smaller than or equal to the power-failure reference threshold value, the
power-failure time determination unit 195a can determine that the power-failure time
is short, and the power-failure time determination unit 195a thus outputs a control
command signal to the air-conditioning control unit 95c.
[0059] The power-failure reference threshold value is set to 10 degrees C as in the first
example. The power-failure reference threshold value may be varied as appropriate
in accordance, for example, the amount of refrigerant in the air-conditioning apparatus
100A, the type of the compressor 3 and the state of attachement of the heat-transfer
temperature detection device 17 or the suction temperature detection device 11. That
is, when the temperature difference ΔTinv is smaller than or equal to a power-failure
reference threshold value which is set in accordance with, for example, the amount
of refrigerant in the air-conditioning apparatus 100, the compressor 3 can be prevented
from being damaged even when the compressor protection control is not performed.
[0060] As described above, the outdoor-unit control device 9A indirectly determines, when
supplying of power is restarted, whether or not the power-failure time is short, based
on the heat-transfer temperature detected by the heat-transfer temperature detection
device 17, and executes protection necessity determination processing of determining
whether or not to execute the compressor protection control before shifting to the
normal operation control.
[0061] It should be noted that the temperature difference calculation unit 194 may store
the temperature difference ΔTinv in the storage unit 93 or the like, instead of outputting
the temperature difference ΔTinv to the operation control unit 195. In this case,
the power-failure time determination unit 195a may read out the temperature difference
ΔTinv from the storage unit 93 or the like, and perform determination processing.
[0062] Fig. 6 is a flowchart illustrating the operation of the air-conditioning apparatus
100A as illustrated in Fig. 4. A control operation by the outdoor-unit control device
9A will be described with reference to Fig. 6, by referring mainly to the protection
necessity determination processing.
[0063] First, the temperature storage processing unit 192 is on standby until the power-failure
detection unit 91 detects a power failure (NO in step S201 in Fig. 6). When the power-failure
detection unit 91 detects a power failure (YES in step S201 in Fig. 6), the temperature
storage processing unit 192 stores information indicating the heat-transfer temperature
Tinv
off detected by the heat-transfer temperature detection device 17 in the storage unit
93 (step S202 in Fig. 6). The operation of the air-conditioning apparatus 100A is
in a stopped state until supplying of power from the commercial power supply 500 is
restarted (NO in step S203 in Fig. 6).
[0064] When supplying of power from the commercial power supply 500 is restarted (YES in
step S203 in Fig. 6), the temperature storage processing unit 192 stores the heat-transfer
temperature Tinv
on detected by the heat-transfer temperature detection device 17 in the storage unit
93 (step S204 in Fig. 6).
[0065] Next, the temperature difference calculation unit 94 reads out the heat-transfer
temperature Tinv
off and the heat-transfer temperature Tinv
on stored in the storage unit 93, and calculates he temperature difference ΔTinv by
subtracting the heat-transfer temperature Tinv
on from the heat-transfer temperature Tinv
off (step S205 in Fig. 6).
[0066] The operation control unit 195 compares the temperature difference ΔTinv calculated
by the temperature difference calculation unit 94 with the power-failure reference
threshold value to determine whether or not the temperature difference ΔTinv is greater
than the power-failure reference threshold value (step S206 in Fig. 6). When the temperature
difference ΔTinv is greater than the power-failure reference threshold value (YES
in step S206 in Fig. 6), the operation control unit 195 performs the compressor protection
control (step S207 in Fig. 6), and then rotationally drives the compressor 3 to perform
the normal operation control (step S208 in Fig. 6). On the other hand, when the temperature
difference ΔTinv is smaller than or equal to the power-failure reference threshold
value (NO in step S206 in Fig. 6), the operation control unit 195 rotationally drives
the compressor 3 to perform the normal operation control without performing the compressor
protection control (step S208 in Fig. 6).
[0067] As described above, in the air-conditioning apparatus 100A according to the first
embodiment, when a power failure occurs, the power-failure detection unit 91 detects
the power failure, and stores the heat-transfer temperature Tinv
off in the storage unit 93. When supplying of power is restarted after occurrence of
the power failure, the air-conditioning apparatus 100A automatically restarts to operate.
At this time, the air-conditioning apparatus 100A compares the heat-transfer temperature
Tinv
on obtained after restating of supplying of power with the heat-transfer temperature
Tinv
off to determine whether or not to perform the compressor protection control, based on
the result of the comparison.
[0068] To be more specific, when the temperature difference ΔTinv between the heat-transfer
temperature Tinv
on and the heat-transfer temperature Tinv
off is smaller than or equal to the power-failure reference threshold value, the air-conditioning
apparatus 100A omits the compressor protection control, and returns to the normal
operation control which was performed before occurrence of the power failure. On the
other hand, when the temperature difference ΔTinv is greater than the power-failure
reference threshold value, the air-conditioning apparatus 100A executes the compressor
protection control, and after the compressor protection control is ended, the air-conditioning
apparatus 100A returns to the normal operation control which was executed before occurrence
of the power failure. That is, in the case where supplying of power is restarted after
a short time elapses from occurrence of the power failure, the air-conditioning apparatus
100A can omit the compressor protection control, which is unnecessary in this case,
and can thus rapidly cause the compressor 3 to be operated at the capacity at which
the compressor 3 was operated before occurrence of the power failure, and can also
rapidly restore the state of the air in the to-be-air-conditioned space to the air-conditioned
state thereof prior to occurrence the power failure.
[0069] Furthermore, since the time required until the temperature of the heat-transfer fin
14a lowers by the power-failure reference threshold value is shorter than the time
required until refrigerant accumulates in the compressor 3, the refrigerant does not
accumulate in the compressor 3 within the time required until the temperature of the
heat-transfer fin 14a lowers by the power-failure reference threshold value. Therefore,
in the case where the temperature difference ΔTinv is smaller than or equal to the
power-failure reference threshold value, the air-conditioning apparatus 100A can omit
the compressor protection control without damaging the compressor 3.
[0070] Therefore, in the air-conditioning apparatus 100A, even if a condition during the
power failure, for example, the temperature of air during the power failure, changes,
it can be rapidly adjusted, and the state of air in the to-be-air-conditioned space
can be rapidly restored to the air-conditioned state thereof prior to the power failure.
Thus, the reliability is ensured.
[0071] Furthermore, it should be noted that the temperature of the heat-transfer fin 14a
provided at the inverter device 14 varies in accordance with the ambient temperature
of the inverter device 14 and the operation capacity of the compressor 3, but does
not vary in accordance with the amount of refrigerant. Therefore, the air-conditioning
apparatus 100A can more accurately determine whether a power recovery is made from
the power failure state in a short time period or not.
[0072] Fig. 4 illustrates by way of example the case where the heat-transfer temperature
detection device 17 is provided at the heat-transfer fin 14a; however, this is an
example, and is not limitative. That is, the heat-transfer temperature detection device
17 may be provided at the first heat-transfer fin 15a or the second heat-transfer
fin 16a. In this case, the outdoor-unit control device 9A may perform the protection
necessity determination processing or the like based on the heat-transfer temperature
detected by the heat-transfer temperature detection device 17 provided at the first
heat-transfer fin 15a or the second heat-transfer fin 16a.
[0073] In particular, since the change of the internal temperature of a room corresponding
to the to-be-air-conditioned space is relatively smaller than that of the outside
of the room, the protection necessity determination processing can be more accurately
performed than in the case where the heat-transfer temperature detection device 17
is provided at the second heat-transfer fin 16a provided in the indoor unit 2.
Second example
[0074] Fig. 7 is a schematic diagram illustrating a configuration of an air-conditioning
apparatus according to the second example not according to the invention. A configuration
of a configuration of an air-conditioning apparatus 100B will be overall described
with reference to Fig. 7. Components which are the same or similar to those in the
air-conditioning apparatus 100 and the air-conditioning apparatus 100A according to
the first example and the first embodiment described above will be denoted by the
same reference signs, and their descriptions will thus be omitted.
[0075] As illustrated in Fig. 7, the outdoor unit 1 of the air-conditioning apparatus 100B
includes an outdoor-unit control device 9B, a power-failure time measurement device
18, and a standby power supply device 19. The power-failure time measurement device
18 is a timer which measures time, and measures a power-failure time, which is a period
of time for which a power-failure state continues. The standby power supply device
19 is, for example, a battery, and supplies power to the power-failure time measurement
device 18 during a power failure.
[0076] Fig. 8 is a block diagram illustrating a functional configuration of the outdoor-unit
control device 9B as illustrated in Fig. 7. The outdoor-unit control device 9B includes
a power-failure time processing unit 296 and an operation control unit 295 including
a power-failure time determination unit 295a.
[0077] The power-failure time processing unit 296 outputs a measurement start command to
the power-failure time measurement device 18 when the power-failure detection unit
91 detects a power failure. That is, the power-failure time measurement device 18
starts to measure time in response to the measurement start command from the power-failure
time processing unit 296. Furthermore, the power-failure time processing unit 296
outputs a measurement stop command to the power-failure time measurement device 18
when supplying of power from the commercial power supply 500 is restarted. That is,
the power-failure time measurement device 18 stops measurement of time in response
to the measurement stop command from the power-failure time processing unit 296.
[0078] The power-failure time processing unit 296 acquires the time measured by the power-failure
time measurement device 18 as a power-failure time Tpf. Furthermore, the power-failure
time processing unit 296 has a function of outputting the power-failure time Tpf acquired
from the power-failure time measurement device 18 to the power-failure time determination
unit 295a.
[0079] The power-failure time determination unit 295a compares the power-failure time Tpf
with a power-failure reference time to determine whether or not the power-failure
time Tpf is longer than the power-failure reference time. When the power-failure time
Tpf is longer than the power-failure reference time, the power-failure time determination
unit 295a outputs a control command signal to the protection control unit 95b. By
contrast, when the power-failure time Tpf is smaller than or equal to the power-failure
reference time, the power-failure time determination unit 295a outputs a control command
signal to the air-conditioning control unit 95c.
[0080] It should be noted that several hours are taken until refrigerant accumulates in
the compressor 3. Further, the time required until the refrigerant accumulates in
the compressor 3 after occurrence of power failure varies in accordance with, for
example, the amount of refrigerant in the air-conditioning apparatus 100B and the
type of the compressor 3. Therefore, the power-failure reference time is set in accordance
with, for example, the amount of refrigerant in the air-conditioning apparatus 100B
and the type of the compressor 3. In the case where it is assumed that the refrigerant
accumulates in the compressor 3 relatively early, the power-failure reference time
is set to, for example, 60 minutes.
[0081] As described above, the outdoor-unit control device 9B directly determines whether
or not the power-failure time is short, based on the power-failure time Tpf which
is measured by the power-failure time measurement device 18 when supplying of power
is restarted, and performs the protection necessity determination processing of determining
whether or not to perform the compressor protection control before shifting to the
normal operation control.
[0082] In this case, at least one of the power-failure time measurement device 18 and the
standby power supply device 19 may be provided in the outdoor-unit control device
9B. Furthermore, the power-failure time measurement device 18 and the standby power
supply device 19 may be provided in the indoor unit 2. In this case, for example,
at least one of the power-failure time measurement device 18 and the standby power
supply device 19 may be provided in the indoor-unit control device 10.
[0083] The power-failure time processing unit 296 may store the power-failure time Tpf in
an internal memory (not shown) or the like, instead of outputting the power-failure
time Tpf to the power-failure time determination unit 295a. In this case, the power-failure
time determination unit 295a may read out the power-failure time Tpf from the internal
memory or the like, and perform the determination processing.
[0084] Fig. 9 is a flowchart illustrating the operation of the air-conditioning apparatus
100B as illustrated in Fig. 7. A control operation by the outdoor-unit control device
9B will be described with reference to Fig. 9, by referring mainly to the protection
necessity determination processing.
[0085] First, the power-failure detection unit 91 is on standby until a power failure is
detected (NO in step S301 Fig. 9). When the power-failure detection unit 91 detects
a power failure (YES in step S301 in Fig. 9), the power-failure time processing unit
296 outputs a measurement start command to the power-failure time measurement device
18 to cause the power-failure time measurement device 18 to start to measure time
(step S302 in Fig. 9). The operation of the air-conditioning apparatus 100B is in
the stopped state until supplying of power from the commercial power supply 500 is
restarted (NO in step S303 in Fig. 9).
[0086] When supplying of power from the commercial power supply 500 is restarted (YES in
step S303 in Fig. 9), the power-failure time processing unit 296 outputs a measurement
stop command to the power-failure time measurement device 18 to cause the power-failure
time measurement device 18 to stop measurement of time. Then, the power-failure time
processing unit 296 acquires the power-failure time Tpf measured by the power-failure
time measurement device 18 (step S304 in Fig. 9).
[0087] Next, the operation control unit 295 compares the power-failure time Tpf with the
power-failure reference time to determine whether or not the power-failure time Tpf
is greater than the power-failure reference time (step S305 in Fig. 9). When the power-failure
time Tpf is greater than the power-failure reference time (YES in step S305 in Fig.
9), the operation control unit 295 performs the compressor protection control (step
S306 in Fig. 9), and then rotationally drives the compressor 3 to perform the normal
operation control (step S307 in Fig. 9). On the other hand, when the power-failure
time Tpf is shorter than or equal to the power-failure reference time (NO in step
S305 in Fig. 9), the operation control unit 295 rotationally drives the compressor
3 to perform the normal operation control without performing the compressor protection
control (step S307 in Fig. 9).
[0088] As described above, in the case where supplying of power is restarted after a short
time elapses from the power failure, the air-conditioning apparatus 100B can omit
the compressor protection control, which is unnecessary, and can thus rapidly cause
the compressor 3 at the capacity at which the compressor 3 was operated before occurrence
of the power failure, and also rapidly restore the state of the air in the to-be-air-conditioned
space to the air-conditioned state thereof prior to the power failure. That is, in
the air-conditioning apparatus 100B, even if a condition during the power failure,
for example, the temperature of air during the power failure, changes, it can be rapidly
adjusted, and the state of air in the to-be-air-conditioned space can be rapidly restored
to the air-conditioned state thereof prior to the power failure. Thus, the reliability
is ensured.
[0089] It should be noted that the air-conditioning apparatuses 100 and 100A according to
the first example and the first embodiment store temperature information obtained
prior to occurrence of the power failure, and compare the temperature information
with temperature information obtained after a power recovery to execute the protection
necessity determination processing. In this case, in the case where the time required
until the discharge temperature of the compressor 3 or the temperature of the heat-transfer
fin 14a or the like lowers is compared with the time required until refrigerant accumulates
after occurrence of the power failure, as described above, the time required until
the refrigerant accumulates after occurrence of the power failure is longer. Therefore,
even when the discharge temperature of the compressor 3 or the temperature of the
heat-transfer fin 14a or the like is smaller than or equal to the power-failure reference
threshold value, there is a case where a sufficient margin is allowed until the refrigerant
accumulates, that is, there is a case where the refrigerant does not accumulate, although
this depends on the accuracy of setting the power-failure reference threshold value.
[0090] In view of this point, the air-conditioning apparatus 100B according to the second
example performs the protection necessity determination processing based on the power-failure
time Tpf measured by the power-failure time measurement device 18, that is, an actually
measured value of the power-failure time. Then, the power-failure reference time to
be compared with the power-failure time Tpf can be set to be longer and in such a
way as to prevent the compressor 3 from being damaged, in direct consideration of
the time required until the refrigerant accumulates after occurrence of the power
failure. That is, the air-conditioning apparatus 100B has a function of directly measuring
the power-failure time, and can thus determine whether or not to perform the compressor
protection control, with higher accuracy. Thus, an operation omitting the unnecessary
compressor protection control can be achieved without losing the reliability.
[0091] In this case, the outdoor unit 1 may include an outside-air temperature detection
device (not shown), which is, for example, a temperature sensor formed of a thermistor,
and detects an outside-air temperature, which is the temperature of outside air. In
this case, the power-failure reference time may be set based on an inside-outside
temperature difference, which is a difference between the outside-air temperature
detected by the outside-air temperature detection device and the temperature of indoor
air which is detected by the suction temperature detection device 11.
[0092] In the case where such a configuration is adopted, for example, the power-failure
time determination unit 295a may acquire information indicating the temperature of
outside air and the temperature of indoor air from the outside-air temperature detection
device and the suction temperature detection device 11 to find out the inside-outside
temperature difference. Then, the power-failure time determination unit 295a may set
the power-failure reference time based on the inside-outside temperature difference,
and apply the set power-failure reference time to the comparison with the power-failure
time Tpf.
[0093] In the case where the inside-outside temperature difference is great, the refrigerant
more easily accumulates in the compressor 3. Therefore, in this case, the power-failure
time determination unit 295a may change the power-failure reference time such that
the greater the inside-outside tmperature difference, the shorter the power-failure
reference time. As a result, the outdoor-unit control device 9B can execute the protection
necessity determination processing with higher accuracy. For example, a temperature
difference time table in which said inside-outside temperature differences and power-failure
reference times are associated with each other may be stored in the internal memory
or the like, and with respect to the found inside-outside temperature difference,
the power-failure time determination unit 295a may refer to the temperature difference
time table to determine an associated power-failure reference time.
[0094] Regarding the above embodiments, a description is made by referring to by way of
example the case where the protection control unit 95b energizes the electric heater
provided in the compressor 3 to perform the compressor protection control; however,
this is an example, and is not limitative. The protection control unit 95b may perform
the compressor protection control by applying, to a coil (not shown) of an electric
motor included in the compressor 3, a voltage which is set low so as not to cause
the electric motor to rotate, and heating the compressor 3 with heat generated by
the coil. In the case of adopting such a configuration, it is not necessary to provide
the electric heat in the compressor 3.
[0095] Furthermore, in the embodiments, the air-conditioning apparatuses 100, 100A and 100B
are described above by way of example as air-conditioning apparatuses dedicated to
the cooling operation, but they are not limited to such air-conditioning apparatuses.
For example, the air-conditioning apparatuses 100, 100A and 100B may be formed to
include a four-way valve which switches the flow of refrigerant, and be thus capable
of performing a heating operation, a defrosting operation, etc. That is, regarding
the above embodiments, it is described above by way of example that the heat-source-side
heat exchanger 4 functions as a condenser, and the load-side heat exchanger 6 functions
as an evaporator; however, the heat-source-side heat exchanger 4 may function as the
evaporator, and the load-side heat exchanger 6 may function as the condenser.
[0096] Moreover, regarding the above examples and the embodiment, it is described above
by way of example that the outdoor-unit control device included in the outdoor unit
1 functions as a main controller, and performs the protection necessity determination
processing, etc.; however, this is an example, and is not limitative. For example,
the indoor-unit control device included in the indoor unit 2 may function as the main
controller to perform the protection necessity determination processing, etc. In the
air-conditioning apparatus according to each of the above embodiments, as its controller,
only one controller may be provided, and may be made to have the functions of both
the outdoor-unit control device and indoor-unit control device.
[0097] In addition, Figs. 1, 4 and 7 illustrate by way of example the air-conditioning
apparatuses 100, 100A and 100B as separate-type air-conditioning apparatuses, in which
the outdoor unit 1 and the indoor unit 2 are separately provided; however, as each
of the air-conditioning apparatuses 100, 100A and 100B, an integrated-type air-conditioning
apparatus may be applied in which the function of the outdoor unit 1 and the function
of the indoor unit 2 are combined.
Reference Signs List
[0098]
1 outdoor unit 2 indoor unit 3 compressor 3a discharge temperature detection device
4 heat-source-side heat exchanger 5 expansion valve 6 load-side heat exchanger 7 heat-source-side
fan 8 load-side fan 9, 9A, 9B outdoor-unit control device 10 indoor-unit control device
11 suction temperature detection device 12 input device 13 refrigerant pipe
14 inverter device 14a heat-transfer fin 15 first inverter device
15a first heat-transfer fin 16 second inverter device 16a second heat-transfer fin
17 heat-transfer temperature detection device 18 power-failure time measurement device
19 standby power supply device 91 power-failure detection unit 92, 192 temperature
storage processing unit
93 storage unit 94, 194 temperature difference calculation unit 95, 195, 295 operation
control unit 95a, 195a, 295a power-failure time determination unit 95b protection
control unit 95c air-conditioning control unit 100, 100A, 100B air-conditioning apparatus
296 power-failure time processing unit.