[Technical Field]
[0001] The present disclosure relates to a refrigerator and a method for controlling the
same.
[Background Art]
[0002] Refrigerators are household appliances that are capable of store objects such as
foods at a low temperature in a storage chamber provided in a cabinet. Since the storage
space is surrounded by heat insulation wall, the inside of the storage space may be
maintained at a temperature less than an external temperature.
[0003] The storage space may be classified into a refrigerating storage space or a freezing
storage space according to a temperature range of the storage space.
[0004] The refrigerator may further include an evaporator for supplying cool air to the
storage space. Air in the storage space is cooled while flowing to a space, in which
the evaporator is disposed, so as to be heat-exchanged with the evaporator, and the
cooled air is supplied again to the storage space.
[0005] Here, if the air heat-exchanged with the evaporator is contained in moisture, when
the air is heat-exchanged with the evaporator, the moisture is frozen on a surface
of the evaporator to generate frost on the surface of the evaporator.
[0006] Since flow resistance of the air acts on the frost, the more an amount of frost frozen
on the surface of the evaporator increases, the more the flow resistance increases.
As a result, heat-exchange efficiency of the evaporator may be deteriorated, and thus,
power consumption may increase.
[0007] Thus, the refrigerator further includes a defroster for removing the frost on the
evaporator.
[0008] A defrosting cycle variable method is disclosed in Korean Patent Publication No.
2000-0004806 that is a prior art document.
[0009] In the prior art document, the defrosting cycle is adjusted using a cumulative operation
time of the compressor and an external temperature.
[0010] However, like the prior art document, when defrosting cycle is determined only using
the cumulative operation time of the compressor and the external temperature, an amount
of frost (hereinafter, referred to as a frost generation amount) on the evaporator
is not reflected. Thus, it is difficult accurately determine the time point at which
the defrosting is required.
[0011] That is, the frost generation amount may increase or decrease according to various
environments such as the user's refrigerator usage pattern and the degree to which
air retains moisture. In the case of the prior art document, there is a disadvantage
in that the defrosting cycle is determined without reflecting the various environments.
[0012] In the prior art document, it is only possible to detect the amount of frost on the
evaporator, but it is impossible to detect a phenomenon in which the cool air passage
through which the cool air circulating inside the refrigerator flows is clogged by
the frost. That is, when frost grows in the cool air inlet, the cool air outlet, or
the blowing fan constituting the cool air passage, resistance to the flow of cool
air occurs, and in some cases, the cool air passage is completely clogged, preventing
the cool air cannot from circulating. When circulation of the cool air is not properly
performed, there is a problem that the cooling performance is greatly deteriorated,
and power consumption is increased.
[Disclosure]
[Technical Problem]
[0013] An object of the present disclosure is to provide a refrigerator and a control method
thereof, which determines a time point for a defrosting operation using parameters
that vary depending on the amount of frost on an evaporator.
[0014] In addition, an object of the present disclosure is to provide a refrigerator and
a control method thereof, which accurately determine a time point at which defrosting
is necessary according to the amount of frost on an evaporator using a sensor having
an output value that varies depending on the flow rate of air.
[0015] In addition, another object of the present disclosure is to provide a refrigerator
and a control method thereof, which accurately determine an exact defrost time point
even when the precision of a sensor used to determine the defrost time point is low.
[0016] Still another object of the present disclosure is to provide a refrigerator capable
of detecting clogging of an air passage of the refrigerator using a sensor of which
an output value varies according to a flow rate of air and a control method thereof.
[0017] Still another object of the present disclosure is to provide a refrigerator capable
of accurately determining the cause of clogging of an air passage based on an output
value of a sensor, and a control method thereof.
[Technical Solution]
[0018] In order to resolve the above problems, a method for controlling a refrigerator may
include detecting clogging of an air passage in the heat-exchange space based on a
temperature difference between a first detection temperature (Ht1) that is a lowest
value and a second detection temperature (Ht2) that is a highest value among detection
temperatures of a heat generating element.
[0019] The first detection temperature (Ht1) may be a temperature detected by a sensing
element of the sensor immediately after the heat generating element is turned on,
and the second detection temperature (Ht2) may be a temperature detected by a sensing
element of the sensor immediately after the heat generating element is turned off.
[0020] The first detection temperature (Ht1) may be a lowest temperature value during a
period of time when the heat generating element is turned on, and the second detection
temperature (Ht2) may be a highest temperature value during a period of time when
the heat generating element is turned on.
[0021] The method may further include performing a defrosting operation of the evaporator
when a temperature difference value between the first detection temperature (Ht1)
and the second detection temperature (Ht2) is less than a first reference value.
[0022] The method may further include updating a temperature difference value between the
first detection temperature (Ht1) and the second detection temperature (Ht2) after
the defrosting operation is completed, and failure of the sensor may be displayed
when the updated temperature difference value exceeds a second reference value greater
than the second reference value.
[0023] The method may further include determining whether the updated temperature difference
value is less than a third reference value less than the second reference value when
the updated temperature difference value is less than the second reference value,
and displaying the clogging of the air passage in the heat-exchange space when the
updated temperature difference value exceeds the third reference value.
[0024] The display of the clogging of the air passage is at least one display of clogging
of a cool air inflow hole of a cool air duck defining the heat-exchange space, clogging
of a cool air discharge hole of the cool air duck, clogging of a blowing fan provided
in the cool air duct or clogging of the bypass passage.
[0025] Therefore, even after the defrosting operation is completed, it is possible to identify
whether the air passage of the refrigerator is clogged by using the output value of
the sensor and immediately notify a user of clogging of the air passage, thus making
it possible to take measures immediately when the clogging of the air passage occurs.
Therefore, it is possible to determine not only the cause of the clogging of the air
passage, but also whether the sensor is malfunctioning, thus achieving accurate diagnosis
and making maintenance and management easy.
[0026] The method may further include determining whether the updated temperature difference
value is less than a fourth reference value less than the third reference value when
the updated temperature difference value is less than the third reference value, and
again performing the defrosting operation of the evaporator when the updated temperature
difference value is less than the fourth reference value.
[0027] The method may further include determining whether the updated temperature difference
value is increased by a predetermined value or more compared to the temperature difference
value before the temperature difference value has been updated when the updated temperature
difference value is less than the fourth reference value, and again performing the
defrosting operation of the evaporator when the updated temperature difference value
is increased by a predetermined value or more compared to the temperature difference
value before the temperature difference value has been updated.
[0028] The method may further include again performing the defrosting operation of the evaporator
according to whether the updated temperature difference value is less than the first
reference value when the updated temperature difference value is not increased by
a predetermined value or more compared to the temperature difference value before
the temperature difference value has been updated.
[0029] In order to resolve the above problems, a refrigerator a bypass passage configured
to allow air flow to bypass the evaporator, a heat generating element disposed in
the bypass passage, a sensor including a sensing element for detecting a temperature
of the heat generating element and a controller configured to detect clogging of an
air passage in the heat-exchange space based on a temperature difference between a
first detection temperature (Ht1) that is a lowest value and a second detection temperature
(Ht2) that is a highest value among detection temperatures of the heat generating
element.
[Advantageous Effects]
[0030] According to the proposed invention, since the time point at which the defrosting
is required is determined using the sensor having the output value varying according
to the amount of frost generated on the evaporator in the bypass passage, the time
point at which the defrosting is required may be accurately determined.
[0031] In addition, even when the precision of a sensor used to determine a defrost time
point is low, it is possible to accurately determine the defrost time point, thus
significantly reducing the cost of the sensor.
[0032] Even after the defrosting operation is completed, it is possible to identify whether
the air passage of the refrigerator is clogged by using the output value of the sensor
and immediately notify a user of clogging of the air passage, thus making it possible
to take measures immediately when the clogging of the air passage occurs.
[0033] Therefore, it is possible to determine not only the cause of the clogging of the
air passage, but also whether the sensor is malfunctioning, thus achieving accurate
diagnosis and making maintenance and management easy.
[0034] It is possible to prevent a phenomenon that the air passage is completely clogged
by frost, thus improving cooling performance by active air circulation by fundamentally
preventing the growth of frost in the air passage.
[Description of Drawings]
[0035]
FIG. 1 is a schematic longitudinal cross-sectional view of a refrigerator according
to an embodiment of the present invention.
FIG. 2 is a perspective view of a cool air duct according to an embodiment of the
present invention.
FIG. 3 is an exploded perspective view illustrating a state in which a passage cover
and a sensor are separated from each other in the cool air duct.
FIG. 4 is a view illustrating a flow of air in a heat exchange space and a bypass
passage before and after frost is generated.
FIG. 5 is a schematic view illustrating a state in which a sensor is disposed in the
bypass passage.
FIG. 6 is a view of the sensor according to an embodiment of the present invention.
FIG. 7 is a view illustrating a thermal flow around the sensor depending on a flow
of air flowing through the bypass passage.
FIG. 8 is a control block diagram of a refrigerator according to an embodiment of
the present disclosure.
FIG. 9 is a flowchart showing a method of performing a defrost operation by determining
a time point when a refrigerator needs to be defrosted according to an embodiment
of the present disclosure.
FIG. 10 is a view showing changes in a temperature of a heat generating element according
to the on/off of the heat generating element before and after frost on the evaporator
according to an embodiment of the present disclosure.
FIG. 11 is a flowchart schematically showing a method of detecting clogging of an
air passage of a refrigerator according to an embodiment of the present disclosure.
FIG. 12 is a flowchart showing a detailed method for detecting clogging of an air
passage of a refrigerator according to an embodiment of the present disclosure.
[Mode for Invention]
[0036] Hereinafter, some embodiments of the present invention will be described in detail
with reference to the accompanying drawings. Exemplary embodiments of the present
invention will be described below in more detail with reference to the accompanying
drawings. It is noted that the same or similar components in the drawings are designated
by the same reference numerals as far as possible even if they are shown in different
drawings. Further, in description of embodiments of the present disclosure, when it
is determined that detailed descriptions of well-known configurations or functions
disturb understanding of the embodiments of the present disclosure, the detailed descriptions
will be omitted.
[0037] Also, in the description of the embodiments of the present disclosure, the terms
such as first, second, A, B, (a) and (b) may be used. Each of the terms is merely
used to distinguish the corresponding component from other components, and does not
delimit an essence, an order or a sequence of the corresponding component. It should
be understood that when one component is "connected", "coupled" or "joined" to another
component, the former may be directly connected or jointed to the latter or may be
"connected", coupled" or "joined" to the latter with a third component interposed
therebetwee.
[0038] FIG. 1 is a schematic longitudinal cross-sectional view of a refrigerator according
to an embodiment of the present invention, FIG. 2 is a perspective view of a cool
air duct according to an embodiment of the present invention, and FIG. 3 is an exploded
perspective view illustrating a state in which a passage cover and a sensor are separated
from each other in the cool air duct.
[0039] Referring to FIGS. 1 to 3, a refrigerator 1 according to an embodiment of the present
invention may include an inner case 12 defining a storage space 11.
[0040] The storage space may include one or more of a refrigerating storage space and a
freezing storage space.
[0041] A cool air duct 20 providing a passage, through which cool air supplied to the storage
space 11 flows, in a rear space of the storage space 11. Also, an evaporator 30 is
disposed between the cool air duct 20 and a rear wall 13 of the inner case 12. That
is, a heat exchange space 222 in which the evaporator 30 is disposed is defined between
the cool air duct 20 and the rear wall 13.
[0042] Thus, air of the storage space 11 may flow to the heat exchange space 222 between
the cool air duct 20 and the rear wall 13 of the inner case 12 and then be heat-exchanged
with the evaporator 30. Thereafter, the air may flow through the inside of the cool
air duct 20 and then be supplied to the storage space 11.
[0043] The cool air duct 20 may include, but is not limited thereto, a first duct 210 and
a second duct 220 coupled to a rear surface of the first duct 210.
[0044] A front surface of the first duct 210 is a surface facing the storage space 11, and
a rear surface of the first duct 220 is a surface facing the rear wall 13 of the inner
case 12.
[0045] A cool air passage 212 may be provided between the first duct 210 and the second
duct 220 in a state in which the first duct 210 and the second duct 220 are coupled
to each other.
[0046] Also, a cool air inflow hole 221 may be defined in the second duct 220, and a cool
air discharge hole 211 may be defined in the first duct 210.
[0047] A blower fan (not shown) may be provided in the cool air passage 212. Thus, when
the blower fan rotates, air passing through the evaporator 13 is introduced into the
cool air passage 212 through the cool air inflow hole 221 and is discharged to the
storage space 11 through the cool air discharge hole 211.
[0048] The evaporator 30 is disposed between the cool air duct 20 and the rear wall 13.
Here, the evaporator 30 may be disposed below the cool air inflow hole 221.
[0049] Thus, the air in the storage space 11 ascends to be heat-exchanged with the evaporator
30 and then is introduced into the cool air inflow hole 221.
[0050] According to this arrangement, when an amount of frost generated on the evaporator
30 increases, an amount of air passing through the evaporator 30 may be reduced to
deteriorate heat exchange efficiency.
[0051] In this embodiment, a time point at which defrosting for the evaporator 30 is required
may be determined using a parameter that is changed according to the amount of frost
generated on the evaporator 30.
[0052] For example, the cool air duct 20 may further include a frost generation sensing
portion configured so that at least a portion of the air flowing through the heat
exchange space 222 is bypassed and configured to determine a time point, at which
the defrosting is required, by using the sensor having a different output according
to a flow rate of the air.
[0053] The frost generation sensing portion may include a bypass passage 230 bypassing at
least a portion of the air flowing through the heat exchange space 222 and a sensor
270 disposed in the bypass passage 230.
[0054] Although not limited, the bypass passage 230 may be provided in a recessed shape
in the first duct 210. Alternatively, the bypass passage 230 may be provided in the
second duct 220.
[0055] The bypass passage 230 may be provided by recessing a portion of the first duct 210
or the second duct 220 in a direction away from the evaporator 30.
[0056] The bypass passage 230 may extend from the cool air duct 20 in a vertical direction.
[0057] The bypass passage 230 may be disposed to face the evaporator 30 within a left and
right width range of the evaporator 30 so that the air in the heat exchange space
222 is bypassed to the bypass passage 230.
[0058] The frost generation sensing portion may further include a passage cover 260 that
allows the bypass passage 230 to be partitioned from the heat exchange space 222.
[0059] The passage cover 260 may be coupled to the cool air duct 20 to cover at least a
portion of the bypass passage 230 extending vertically.
[0060] The passage cover 260 may include a cover plate 261, an upper extension portion 262
extending upward from the cover plate 261, and a barrier 263 provided below the cover
plate 261.
[0061] FIG. 4 is a view illustrating a flow of air in the heat exchange space and the bypass
passage before and after frost is generated.
[0062] (a) of FIG. 4 illustrates a flow of air before frost is generated, and (b) of FIG.
4 illustrates a flow of air after frost is generated. In this embodiment, as an example,
it is assumed that a state after a defrosting operation is complicated is a state
before frost is generated.
[0063] First, referring to (a) of FIG. 4, in the case in which frost does not exist on the
evaporator 30, or an amount of generated frost is remarkably small, most of the air
passes through the evaporator 30 in the heat exchange space 222 (see arrow A). On
the other hand, some of the air may flow through the bypass passage 230 (see arrow
B).
[0064] Referring to (b) of FIG. 4, when the amount of frost generated on the evaporator
30 is large (when the defrosting is required), since the frost of the evaporator 30
acts as flow resistance, an amount of air flowing through the heat exchange space
222 may decrease (see arrow C), and an amount of air flowing through the bypass passage
230 may increase (see arrow D).
[0065] As described above, the amount (or flow rate) of air flowing through the bypass passage
230 varies according to an amount of frost generated on the evaporator 30.
[0066] In this embodiment, the sensor 270 may have an output value that varies according
to a change in flow rate of the air flowing through the bypass passage 230. Thus,
whether the defrosting is required may be determined based on the change in output
value.
[0067] Hereinafter, a structure and principle of the sensor 270 will be described.
[0068] FIG. 5 is a schematic view illustrating a state in which the sensor is disposed in
the bypass passage, FIG. 6 is a view of the sensor according to an embodiment of the
present invention, and FIG. 7 is a view illustrating a thermal flow around the sensor
depending on a flow of air flowing through the bypass passage.
[0069] Referring to FIGS. 5 to 7, the sensor 270 may be disposed at one point in the bypass
passage 230. Thus, the sensor 270 may contact the air flowing along the bypass passage
230, and an output value of the sensor 270 may be changed in response to a change
in a flow rate of air.
[0070] The sensor 270 may be disposed at a position spaced from each of an inlet 231 and
an outlet 232 of the bypass passage 230. For example, the sensor 270 may be positioned
a central portion of the bypass passage 230.
[0071] Since the sensor 270 is disposed on the bypass passage 230, the sensor 270 may face
the evaporator 30 within the left and right width range of the evaporator 30.
[0072] The sensor 270 may be, for example, a generated heat temperature sensor. Particularly,
the sensor 270 may include a sensor PCB 271, a heat generating element 273 installed
on the sensor PCB 271, and a sensing element 274 installed on the sensor PCB 271 to
sense a temperature of the heat generating element 273.
[0073] The heat generating element 273 may be a resistor that generates heat when current
is applied.
[0074] The sensing element 274 may sense a temperature of the heat generating element 273.
[0075] When a flow rate of air flowing through the bypass passage 230 is low, since a cooled
amount of the heat generating element 273 by the air is small, a temperature sensed
by the sensing element 274 is high.
[0076] On the other hand, if a flow rate of the air flowing through the bypass passage 230
is large, since the cooled amount of the heat generating element 273 by the air flowing
through the bypass passage 230 increases, a temperature sensed by the sensing element
274 decreases.
[0077] The sensor PCB 271 may determine a difference between a temperature sensed by the
sensing element 274 in a state in which the heat generating element 273 is turned
off and a temperature by the sensing element 274 in a state in which the heat generating
element 273 is turned on.
[0078] The sensor PCB 271 may determine whether the difference value between the states
in which the heat generating element 273 is turned on/off is less than a reference
difference value.
[0079] For example, referring to FIGS. 4 and 7, when an amount of frost generated on the
evaporator 30 is small, a flow rate of air flowing to the bypass passage 230 is small.
In this case, a heat flow of the heat generating element 273 is little, and a cooled
amount of the heat generating element 273 by the air is small.
[0080] On the other hand, when the amount of frost generated on the evaporator 30 is large,
a flow rate of air flowing to the bypass passage 230 is large. Then, the heat flow
and cooled amount of the heat generating element 273 are large by the air flowing
along the bypass passage 230.
[0081] Thus, the temperature sensed by the sensing element 274 when the amount of frost
generated on the evaporator 30 is large is less than that sensed by the sensing element
274 when the amount of frost generated on the evaporator 30 is small.
[0082] Thus, in this embodiment, when the difference between the temperature sensed by the
sensing element 274 in the state in which the heat generating element 273 is turned
on and the temperature by the sensing element 274 in the state in which the heat generating
element 273 is turned off is less than the reference temperature difference, it may
be determined that the defrosting is required.
[0083] According to this embodiment, the sensor 270 may sense a variation in temperature
of the heat generating element 273, which varies by the air of which a flow rate varies
according to the amount of generated frost to accurately determine a time point, at
which the defrosting is required, according to the amount of frost generated on the
evaporator 30.
[0084] The sensor 270 may be further provided with a sensor housing 272 such that air flowing
through the bypass passage 230 is prevented from directly contacting the sensor PCB
271, the heat generating element 273, and the temperature sensor 274. In a state in
which the sensor housing 272 is opened at one side, an electric wire connected to
the sensor PCB 271 may be drawn out and then the opened portion may be covered by
a cover portion.
[0085] The sensor housing 271 may surround the sensor PCB 271, the heat generating element
273, and the temperature sensor 274.
[0086] FIG. 8 is a control block diagram of a refrigerator according to an embodiment of
the present disclosure.
[0087] Referring to FIG. 8, the refrigerator 1 according to an embodiment of the present
disclosure may include the sensor 270 described above, a defrosting device 50 operating
for defrosting the evaporator 30, a compressor 60 for compressing refrigerant, a blowing
fan 70 for generating air flow, and a controller 40 for controlling the sensor 270,
the defrosting device 50, the compressor 60 and the blowing fan 70.
[0088] The defrosting device 50 may include, for example, a heater. When the heater is turned
on, heat generated by the heater is transferred to the evaporator 30 to melt frost
generated on the surface of the evaporator 30. The heater may be connected to one
side of the evaporator 30, or may be disposed spaced apart from a position adjacent
to the evaporator 30. The defrosting device 50 may further include a defrost temperature
sensor. The defrost temperature sensor may detect an ambient temperature of the defrosting
device 50. A temperature value detected by the defrost temperature sensor may be used
as a factor that determines when the heater is turned on or off.
[0089] The compressor 60 is a device for compressing low-temperature low-pressure refrigerant
into a high-temperature high-pressure supersaturated gaseous refrigerant. Specifically,
the high-temperature high-pressure supersaturated gaseous refrigerant compressed in
the compressor 60 flows into a condenser (not shown). The refrigerant is condensed
into a high-temperature high-pressure saturated liquid refrigerant, and the condensed
high-temperature high-pressure saturated liquid refrigerant is introduced to an expander
(not shown) and is expanded to a low-temperature low-pressure two-phase refrigerant.
[0090] Further, the low-temperature low-pressure two-phase refrigerant is evaporated as
the low-temperature low-pressure gaseous refrigerant while passing through the evaporator
30. In this process, the refrigerant flowing through the evaporator 30 may exchange
heat with outside air, that is, air flowing through the heat exchange space 222, thereby
archiving air cooling.
[0091] The blowing fan 70 is provided in the cool air passage 212 to generate air flow.
Specifically, when the blowing fan 70 is rotated, air passing through the evaporator
30 flows into the cool air passage 212 through the cool air inflow hole 221 and is
then discharged to the storage compartment 11 through the cool air discharge hole
211.
[0092] The controller 40 may control the heat generating element 273 of the sensor 270 to
be turned on at regular cycles.
[0093] In order to determine when defrosting is necessary, the heat generating element 273
may maintain a turned-on state for a predetermined period of time, and the temperature
of the heat generating element 273 may be detected by the sensing element 274.
[0094] After the heat generating element 273 is turned on for the predetermined period of
time, the heat generating element 274 is turned off, and the sensing element 274 may
detect the temperature of the heat generating element 273 which is turned off. In
addition, the sensor PCB 263 may determine whether the maximum value of the temperature
difference between the turned-on/off state of the heat generating element 273 is equal
to or less than a reference difference value.
[0095] In addition, it is determined that defrosting is necessary when the maximum value
of the temperature difference between the turned-on/off states of the heat generating
element 273 is equal to or less than the reference difference value, and the defrosting
device 50 may be turned on by the controller 40.
[0096] Although it has been described above that the sensor PCB 263 determines whether the
temperature difference between the turned-on/off states of the heat generating element
273 is equal to or less than the reference difference value, alternatively, the controller
40 may determine whether the temperature difference between the turned-on/off states
of the heat generating element 273 is equal to or less than the reference difference
value, and control the defrosting device 50 according to a result of the determination.
That is, the sensor PCB 263 and the controller 40 may be electrically connected to
each other.
[0097] The controller 40 may detect a temperature of the heat generating element 273 in
a state in which the heat generating element 273 is turned on or off, and detect clogging
of an air passage based on a temperature difference value between a first detection
temperature and a second detection temperature among the detection temperatures of
the heat generating element 273.
[0098] For example, the first detection temperature may be a temperature detected by the
sensing element 274 immediately after the heat generating element 273 is turned on,
and the second detection temperature may be a temperature detected by the sensing
element 274 immediately after the heat generating element 273 is turned off.
[0099] As another example, the first detection temperature may be a lowest temperature value
during a period of time when the heat generating element 273 is turned on, and the
second detection temperature may be a highest temperature value during a period of
time when the heat generating element 273 is turned on.
[0100] Hereinafter, a method for detecting the amount of frost on the evaporator 30 using
the heat generating element 273 will be described in detail with reference to the
drawings.
[0101] FIG. 9 is a flowchart showing a method of performing a defrost operation by determining
a time point when a refrigerator needs to be defrosted according to an embodiment
of the present disclosure, and FIG. 10 is a view showing changes in a temperature
of a heat generating element according to the on/off of the heat generating element
before and after frost on the evaporator according to an embodiment of the present
disclosure.
[0102] In FIG. 10, (a) shows a change in temperature of the freezing compartment and a change
in temperature of the heat generating element before occurrence of frost on the evaporator
30, and (b) shows a change in temperature of the freezing compartment and a change
in temperature of the heat generating element after occurrence of frost on the evaporator
30. In the present embodiment, it is assumed that a state before occurrence of frost
is a state after a defrosting operation is completed.
[0103] Referring to FIGS. 9 and 10, in step S21, the heat generating element 27 is turned
on.
[0104] Specifically, the heat generating element 273 may be turned on in a state in which
a cooling operation is being performed on the storage compartment 11 (e.g., freezing
compartment).
[0105] Here, the state in which the cooling operation of the freezing compartment is performed
may mean a state in which the compressor 60 and the blowing fan 70 are being driven.
[0106] As described above, when a change in the flow rate of the air increases as the amount
of frost on the evaporator 30 is large or small, the detection accuracy of the sensor
260 may be improved. That is, when the change in the flow rate of the air is large
as the amount of frost on the evaporator 30 is large or small, the amount of change
in the temperature detected by the sensor 270 becomes large, so that the time point
at the defrosting is necessary may be accurately determined.
[0107] Therefore, it is possible to increase the accuracy of the sensor only when frost
on the evaporator 30 is detected in a state in which air flow occurs, that is, the
blowing fan 70 is being driven.
[0108] As an example, as shown in FIG. 11, the heat generating element 273 may be turned
on at a certain time point S1 while the blowing fan 70 is being driven.
[0109] The blower fan 70 may be driven for a predetermined period of time to cool the freezing
compartment. In this case, the compressor 60 may be driven at the same time. Therefore,
when the blowing fan 70 is driven, the temperature Ft of the freezing compartment
may decrease.
[0110] On the other hand, when the heat generating element 273 is turned on, the temperature
detected by the sensing element 274, that is, the temperature Ht of the heat generating
element 273 may increase rapidly.
[0111] Next, in step S22, it may be determined whether the blowing fan 70 is turned on.
[0112] As described above, the sensor 270 may detect a change in temperature of the heat
generating element 273, which is changed due to air of which the flow rate is changed
according to the amount of frost on the evaporator 30. Therefore, when no air flow
occurs, it is difficult for the sensor 270 to accurately detect the amount of front
on the evaporator 30.
[0113] When the blowing fan 70 is being driven, in step S23, the temperature Ht1 of the
heat generating element may be detected.
[0114] Specifically, the heat generating element 273 may be turned on for a predetermined
period of time, and the temperature (Ht1) of the heat generating element 273 may be
detected by the sensing element at a certain time point in the state in which the
heat generating element 273 is turned on.
[0115] In the present embodiment, the temperature Ht1 of the heat generating element 273
may be detected at a time point at which the heat generating element 273 is turned
on. That is, in the present disclosure, the temperature immediately after the heat
generating element 273 is turned on may be detected. Therefore, the detection temperature
Ht1 of the heat generating element may be defined as the lowest temperature in the
state in which the heat generating element 273 is turned on.
[0116] Here, the temperature of the heat generating element 273 detected for the first time
may be referred to as a"first detection temperature (Ht1)".
[0117] Next, in step S24, it is determined whether a first reference time T1 has elapsed
while the heat generating element 273 is turned on.
[0118] When the heat generating element 273 is maintained in the turned-on state, the temperature
detected by the sensing element 274, that is, the temperature Ht1 of the heat generating
element 273 may continuously increase. However, when the heat generating element 273
is maintained in the turned-on state, the temperature of the heat generating element
273 may increase gradually and converge to the highest temperature point.
[0119] On the other hand, when the amount of frost on the evaporator 30 is large, the flow
rate of the air flowing into the bypass passage 230 increases, and thus the amount
of cooling for the heat generating element 273 by air flowing through the bypass passage
230 increases. Then, the highest temperature point of the heat generating element
273 may be set to be low by the air flowing through the bypass passage 230 (see (b)
of FIG. 10).
[0120] When the amount of frost on the evaporator 30 is small, the flow rate of the air
flowing into the bypass passage 230 decreases, and thus the amount of cooling for
the heat generating element 273 by air flowing through the bypass passage 230 decreases.
Then, the highest temperature point of the heat generating element 273 may be set
to be high by the air flowing through the bypass passage 230 (see (a) of FIG. 10).
[0121] In the present embodiment, the temperature of the heat generating element 273 may
be detected at a time point at which the heat generating element 273 is turned on.
That is, in the present disclosure, it can be understood that the lowest temperature
value of the heat generating element 273 is detected after the heat generating element
273 is turned on.
[0122] Here, the first reference time T1 for which the heat generating element 273 is maintained
in the turned-on state may be 3 minutes but is not limited thereto.
[0123] When a predetermined period of time has elapsed while the heat generating element
273 is turned on, in step S25, the heat generating element 273 is turned off.
[0124] As in FIG. 10, the heat generating element 273 may be turned on for the first reference
time T1 and then turned off. When the heat generating element 273 is turned off, the
heat generating element 273 may be rapidly cooled by air flowing through the bypass
passage 230. Therefore, the temperature Ht of the heat generating element 273 may
rapidly decrease.
[0125] However, when the turned-off state of the heat generating element 273 is maintained,
the temperature Ht of the heat generating element may gradually decrease, and the
decrease rate thereof is significantly reduced.
[0126] Next, in step S26, the temperature Ht2 of the heat generating element may be detected.
[0127] That is, the temperature Ht2 of the heat generating element is detected by the sensing
element 273 at a certain time point S2 in a state in which the heat generating element
273 is turned off.
[0128] In the present embodiment, the temperature Ht2 of the heat generating element may
be detected at a time point at which the heat generating element 273 is turned off.
That is, in the present disclosure, the temperature immediately after the heat generating
element 273 is turned off may be detected. Therefore, the detection temperature Ht2
of the heat generating element may be defined as the lowest temperature in the state
in which the heat generating element 273 is turned off.
[0129] Here, the temperature of the heat generating element 273 detected for the second
time may be referred to as a "second detection temperature (Ht2)".
[0130] In summary, the temperature Ht of the heat generating element may be first detected
at a time point S1 when the heat generating element 273 is turned on, and may be additionally
detected at a time point S2 at which the heat generating element 273 is turned off.
In this case, the first detection temperature Ht1 that is detected for the first time
may be the lowest temperature in the state in which the heat generating element 273
is turned on, and the second detection temperature Ht2 that is additionally detected
may be the highest temperature in the state in which the heat generating element 273
is turned off.
[0131] Next, in step S27, it is determined whether a temperature stabilization state has
been achieved.
[0132] Here, the temperature stabilization state may mean a state in which internal refrigerator
load does not occur, that is, a state in which the cooling of the storage compartment
is normally performed. In other words, the fact that the temperature stabilization
state is made may mean that the opening/closing of a refrigerator door is not performed
or there are no defects in components (e.g., a compressor and an evaporator) for cooling
the storage compartment or the sensor 270.
[0133] That is, the sensor 270 may accurately detect the amount of frost on the evaporator
30 by determining whether or not temperature stabilization has been achieved.
[0134] In the present embodiment, in order to determine the temperature stabilization state
is achieved, it is possible to determine the amount of change in the temperature of
the freezing compartment for a predetermined period of time. Alternatively, in order
to determine the temperature stabilization state is achieved, it is possible to determine
the amount of change in the temperature of the evaporator 30 for a predetermined period
of time.
[0135] For example, a state in which the amount of change in temperature of the freezing
compartment or in temperature of the evaporator 30 during the predetermined period
of time does not exceed 1.5 degrees may be defined as the temperature stabilization
state.
[0136] As described above, the temperature Ht of the heat generating element may rapidly
decrease immediately after the heat generating element 273 is turned off, and then
the temperature Ht of the heat generating element may gradually decrease. Here, it
is possible to determine whether temperature stabilization has been achieved by determining
whether the temperature Ht of the heat generating element decreases normally after
decreasing rapidly.
[0137] When the temperature stabilization state is achieved, in step S28, the temperature
difference ΔHt between the temperature Ht1 detected when the heat generating element
273 is turned on and the temperature Ht2 detected when the heat generating element
273 is turned off may be calculated.
[0138] In step S29, it is determined whether the temperature difference ΔHt is less than
a first reference temperature value.
[0139] Specifically, when the amount of frost on the evaporator 30 is large, the flow rate
of the air flowing into the bypass passage 230 increases, and thus the amount of cooling
for the heat generating element 273 by air flowing through the bypass passage 230
may increase. When the amount of cooling increases, the temperature Ht2 of the heat
generating element detected immediately after the heat generating element 273 is turned
off may be relatively low compared to a case where the amount of frost on the evaporator
30 is small.
[0140] As a result, when the amount of frost on the evaporator 30 is large, the temperature
difference ΔHt may be small. Accordingly, it is possible to determine the amount of
frost on the evaporator 30 through the temperature difference ΔHt.
[0141] Here, the first reference temperature value may be 32 degrees, for example.
[0142] Next, when the temperature difference ΔHt is less than the first reference temperature
value, in step S30, a defrosting operation is performed.
[0143] When the defrosting operation is performed, the defrosting device 50 is driven and
heat generated by the heater is transferred to the evaporator 30 so that the frost
generated on the surface of the evaporator 30 is melted.
[0144] On the other hand, in step S27, when the temperature stabilization state is not achieved
or, in step S29, when the temperature difference ΔHt is greater than or equal to the
first reference temperature value, the algorithm ends without performing the defrosting
operation.
[0145] In the present embodiment, the temperature difference value ΔHt may be defined as
a "logic temperature" for detection of frosting. The logic temperature may be used
as a temperature for determining a time point for a defrosting operation of the refrigerator,
and may be used as a temperature for detecting clogging of an air passage, which is
to be described later.
[0146] Meanwhile, in the present disclosure, it may be possible to detect whether the air
passage of the refrigerator is clogged or a sensor failure occurs by determining whether
the temperature difference value between the first detection temperature Ht1 and the
second detection temperature Ht2 is out of a normal range.
[0147] Here, the clogging of the air passage may include at least one or more of clogging
of a passage through which cool air circulating inside the refrigerator flows, that
is, clogging of the cool air inflow hole 221 or the cool air discharge hole 211 of
the cool air duct 20 defining the heat-exchange space 222, clogging of the blowing
fan 70 provided in the cool air duct 20, or clogging of the bypass passage 230.
[0148] The cool air inflow hole 221, the cool air discharge hole 211, the blowing fan 70,
and the bypass passage 230 may be clogged by frost due to condensation of moisture
contained in the air on the surface. As described above, when the air passage is clogged
by growth of frost, there is a problem that air flow resistance is caused, and as
a result, heat exchange efficiency of the evaporator is reduced and power consumption
is increased.
[0149] Accordingly, the present disclosure is characterized in that the cause of the clogging
of the air passage of the refrigerator is diagnosed and appropriate measures are taken
accordingly.
[0150] FIG. 11 is a flowchart schematically showing a method of detecting clogging of an
air passage of a refrigerator according to an embodiment of the present disclosure.
[0151] Referring to FIG. 11, in step S41, the heat generating element 273 is operated for
a predetermined time.
[0152] Specifically, the heat generating element 273 may be turned on for a predetermined
time and then turned off. For example, the heat generating element 273 may be turned
on for 3 minutes.
[0153] Next, in step S43, the controller 40 may detect a temperature of the heat generating
element 273 in a state in which the heat generating element 273 is turned on or off.
[0154] For example, the controller 40 may detect the temperature of the heat generating
element 273 immediately after the heat generating element 273 is turned on and the
heat generating element 273 is turned off.
[0155] As another example, the controller 40 may detect the temperature of the heat generating
element 273 during a period of time when the heat generating element 273 is turned
on.
[0156] Next, in step S45, the controller 40 may detect clogging of the air passage based
on a temperature difference value between the first detection temperature that is
the the lowest value and the second detection temperature that is the the highest
value, among detection temperatures of the heat generating element 273.
[0157] The method of detecting the amount of frost on the evaporator 30 according to a temperature
difference value between the first detection temperature and the second detection
temperature of the heat generating element 273, that is, a logic temperature ΔHt has
been described above.
[0158] However, in the present embodiment, when the logic temperature ΔHt has an abnormally
large value, it may be determined that a failure has occurred in the sensor 270.
[0159] Although the defrosting operation is performed when the logic temperature ΔHt is
less than a reference value, it may be determined that the air passage of the refrigerator
has been clogged when the logic temperature ΔHt is still kept low.
[0160] In this case, the clogging of the air passage may mean that at least one of the cool
air inflow hole 221, the cool air discharge hole 211, the blowing fan 70, and the
bypass passage 230 is clogged. In this case, it is difficult to solve the clogging
of the air passage. That is, when the clogging of the air passage occurs, it is difficult
to remove frost formed in the cool air inflow hole 221, the cool air discharge hole
211, the blowing fan 70, and the bypass passage 230 even though the defrosting operation
is performed. Accordingly, when it is determined that the air passage is clogged,
it may be immediately notified to the user so that the clogging of the air passage
may be resolved.
[0161] FIG. 12 is a flowchart showing a detailed method for detecting clogging of an air
passage of a refrigerator according to an embodiment of the present disclosure.
[0162] Referring to FIG. 12, in step S51, a logic temperature ΔHt may be updated. Here,
updating the logic temperature ΔHt means may that steps S21 to S28 of FIG. 9 described
above are performed again.
[0163] Alternatively, update of the logic temperature may means may that steps S21 to S28
of FIG. 9 described above are performed initially.
[0164] Next, in step S52, the controller 40 may determine whether the updated logic temperature
ΔHt is less than the second reference temperature value. In this case, the second
reference temperature value may be greater than the first reference temperature value.
As an example, the second reference temperature value may be 50 degrees, but is not
limited thereto.
[0165] Here, the reason to determine whether the updated logic temperature ΔHt is less than
the second reference temperature value is to determine whether the updated logic temperature
ΔHt is within a normal range. That is, when the updated logic temperature ΔHt is not
within the normal range, that is, when the updated logic temperature ΔHt has an abnormally
large value, it may be determined that a failure has occurred in the sensor 270.
[0166] For example, the cause of the failure of the sensor 270 may include a case where
a wire of the heat generating element 273 is short-circuited, a case where a wire
of the sensing element 274 is short-circuited, or a case where the heat generating
element 273 is frozen. In this case, the sensor 270 may need to be repaired or replaced.
[0167] Therefore, when the updated logic temperature ΔHt exceeds the second reference temperature
value, in step S53, the controller 40 may display a failure of the sensor 270.
[0168] In step S54, the controller 40 may performs defrosting operation. That is, when a
failure occurs in the sensor 270, the defrosting operation may be normally performed.
[0169] When the updated logic temperature ΔHt is less than the second reference temperature
value, in step S55, the controller 40 may determine whether the updated logic temperature
ΔHt is less than a third reference temperature value. In this case, the third reference
temperature value may be a value less than the second reference temperature value.
As an example, the third reference temperature value may be 45 degrees, but is not
limited thereto.
[0170] The reason to determine whether the logic temperature ΔHt is less than the third
reference temperature value may be to detect clogging of an air passage of the evaporator
1.
[0171] In the present disclosure, when one or more of the air passage of the refrigerator
1, that is, the cool air inflow hole 221, the cool air discharge hole 211, the blowing
fan 70, and the bypass passage 230 are clogged, the flow rate or flow speed of air
may be rapidly reduced, and as a result, the flow rate of air flowing into the bypass
passage 230 may be rapidly decreased. Accordingly, since the flow rate of the air
flowing into the bypass passage 230 is reduced, the temperature of the heat generating
element 273 detected while the heat generating element 273 is turned on may increase
rapidly.
[0172] According to the above-described principle, the fact that the updated logic temperature
ΔHt is measured as being very high may mean that at least one or more of the cool
air inflow hole 221, the cool air discharge hole 211, the blower fan 70, and the bypass
passage 230 are clogged.
[0173] When the updated logic temperature ΔHt exceeds the third reference temperature value,
it may be determined in steps S56 and S57 whether the updated logic temperature ΔHt
exceeds the third reference temperature value for the first time. When the updated
logic temperature ΔHt exceeds the third reference temperature value for the first
time, in step S54, the controller 40 may performs defrosting operation.
[0174] Alternatively, in steps S56 and S57, when the updated logic temperature ΔHt does
not exceed the third reference temperature value for the first time, that is, when
it is determined that clogging of the air passage has still occurred, in step S58,
the controller 40 may display the clogging of the air passage and then perform defrosting
operation.
[0175] According to this configuration, it may be possible to inform a user of the clogging
of the air passage when the clogging of the air passage continuously occurs, so that
accurate diagnosis is possible and maintenance and management are easy.
[0176] On the other hand, when the updated logic temperature ΔHt is less than the third
reference temperature value, in step S59, the controller 40 may determine whether
the updated logic temperature ΔHt is less than a fourth reference temperature value.
In this case, the fourth reference temperature value may be a value less than the
third reference temperature value. For example, the fourth reference temperature value
may be 35 degrees, but is not limited thereto.
[0177] When the updated logic temperature ΔHt exceeds the fourth reference temperature value,
that is, when the updated logic temperature ΔHt is less than the third reference temperature
value and is greater than or equal to the fourth reference temperature value, the
controller 40 may return to step S51 without performing the defrosting operation.
[0178] That is, when the updated logic temperature ΔHt is less than the third reference
temperature value and is greater than or equal to the fourth reference temperature
value, it means a state in which clogging of the air passage occurs.
[0179] Conversely, when the updated logic temperature ΔHt is less than the fourth reference
temperature value, in steps S60 and S61, the controller 40 may determine whether the
updated logic temperature ΔHt exceeds the fourth reference temperature value for the
first time. When the updated logic temperature ΔHt exceeds the fourth reference temperature
value for the first time, in step S62, the controller 40 may determine whether the
updated logic temperature ΔHt is less than the first reference temperature value.
[0180] When the updated logic temperature ΔHt is less than the first reference temperature
value, in step S54, the controller 40 may determines that the amount of frost on the
evaporator 30 is large, and perform defrosting operation.
[0181] When the updated logic temperature ΔHt exceeds the first reference temperature value,
the controller 40 may determine that the air passage has not been clogged, and may
return to step S51 without performing the defrosting operation.
[0182] When the updated logic temperature ΔHt does not exceed the fourth reference temperature
value for the first time in step S60 and step S61, in step S63, the controller 40
may determine whether the updated logic temperature ΔHt has increased by "A" degrees
or more from the previously updated logic temperature.
[0183] Here, the reason to determine whether the updated logic temperature ΔHt has increased
by "A" degrees or more from the previously updated logic temperature is for determining
whether the air passage is being progressively clogged. That is, even when the air
passage is not clogged completely, frost growth in the air passage may be prevented
fundamentally.
[0184] For example, the case where the updated logic temperature ΔHt is significantly higher
than the previously updated logic temperature may mean that the air passage is progressively
clogged, and the amount of cooling of air flowing through the bypass passage 230 is
significantly reduced. That is, when clogging of the air passage is continuously made,
the air passage is completely clogged, causing a problem in that air is not circulated.
[0185] Therefore, when it is determined that the updated logic temperature ΔHt has been
increased by "A" degrees or more from the previously updated logic temperature, in
step S54, the controller 40 may perform a defrosting operation to prevent the air
passage from being clogged.
[0186] When it is determined that the updated logic temperature ΔHt has not been increased
by "A" degrees or more from the previously updated logic temperature, the controller
40 may proceed to step S62.
[0187] Although it has been descried in the present embodiment that the first detection
temperature Ht1 may be a temperature detected by a sensing element of the sensor immediately
after the heat generating element is turned on, and the second detection temperature
Ht2 may be a temperature detected by a sensing element of the sensor immediately after
the heat generating element is turned off, the present embodiment is not limited thereto.
[0188] According to another embodiment, the first detection temperature Ht1 and the second
detection temperature Ht2 may be temperature values detected while the heat generating
element is turned on. For example, the first detection temperature (Ht1) may be a
lowest temperature value during a period of time when the heat generating element
is turned on and the second detection temperature (Ht2) is a highest temperature value
during the period of time when the heat generating element is turned on.
1. A control method of a refrigerator, comprising:
operating a heat generating element of a sensor disposed in a bypass passage for a
predetermined period of time, the bypass passage allowing air flow to bypass an evaporator
disposed in a heat-exchange space;
detecting a temperature of the heat generating element in a state in which the heat
generating element is turned on or off; and
detecting clogging of an air passage in the heat-exchange space based on a temperature
difference between a first detection temperature (Ht1) that is a lowest value and
a second detection temperature (Ht2) that is a highest value among detection temperatures
of the heat generating element.
2. The control method of claim 1, wherein the first detection temperature (Ht1) is a
temperature detected by a sensing element of the sensor immediately after the heat
generating element is turned on.
3. The control method of claim 1, wherein the second detection temperature (Ht2) is a
temperature detected by a sensing element of the sensor immediately after the heat
generating element is turned off.
4. The control method of claim 1, wherein the first detection temperature (Ht1) is a
lowest temperature value during a period of time when the heat generating element
is turned on.
5. The control method of claim 1, wherein the second detection temperature (Ht2) is a
highest temperature value during a period of time when the heat generating element
is turned on.
6. The control method of claim 1, further comprising:
performing a defrosting operation of the evaporator when a temperature difference
value between the first detection temperature (Ht1) and the second detection temperature
(Ht2) is less than a first reference value.
7. The control method of claim 1, further comprising:
updating a temperature difference value between the first detection temperature (Ht1)
and the second detection temperature (Ht2) after the defrosting operation is completed,
wherein failure of the sensor is displayed when the updated temperature difference
value exceeds a second reference value greater than the second reference value.
8. The control method of claim 7, further comprising:
determining whether the updated temperature difference value is less than a third
reference value less than the second reference value when the updated temperature
difference value is less than the second reference value, and
displaying the clogging of the air passage in the heat-exchange space when the updated
temperature difference value exceeds the third reference value.
9. The control method of claim 8, wherein the display of the clogging of the air passage
is at least one display of clogging of a cool air inflow hole of a cool air duck defining
the heat-exchange space, clogging of a cool air discharge hole of the cool air duck,
clogging of a blowing fan provided in the cool air duct or clogging of the bypass
passage.
10. The method of claim 8, further comprising:
determining whether the updated temperature difference value is less than a fourth
reference value less than the third reference value when the updated temperature difference
value is less than the third reference value, and
again performing the defrosting operation of the evaporator when the updated temperature
difference value is less than the fourth reference value.
11. The control method of claim 10, further comprising:
determining whether the updated temperature difference value is increased by a predetermined
value or more compared to the temperature difference value before the temperature
difference value has been updated when the updated temperature difference value is
less than the fourth reference value, and
again performing the defrosting operation of the evaporator when the updated temperature
difference value is increased by a predetermined value or more compared to the temperature
difference value before the temperature difference value has been updated.
12. The control method of claim 10, further comprising:
again performing the defrosting operation of the evaporator according to whether the
updated temperature difference value is less than the first reference value when the
updated temperature difference value is not increased by a predetermined value or
more compared to the temperature difference value before the temperature difference
value has been updated.
13. A refrigerator comprising:
an inner case configured to define a storage space;
a cooling duct configured to guide flow of air in the storage space and define a heat
exchange space with the inner case;
an evaporator disposed in the heat exchange space;
a bypass passage configured to allow air flow to bypass the evaporator;
a sensor including a heat generating element disposed in the bypass passage and a
sensing element configured to detect a temperature of the heat generating element;
and
a controller configured to detect clogging of an air passage in the heat-exchange
space based on a temperature difference between a first detection temperature (Ht1)
that is a lowest value and a second detection temperature (Ht2) that is a highest
value among detection temperatures of the heat generating element.
14. The refrigerator of claim 13, wherein the first detection temperature (Ht1) is a temperature
detected by a sensing element immediately after the heat generating element is turned
on, and
wherein the second detection temperature (Ht2) is a temperature detected by a sensing
element immediately after the heat generating element is turned off.
15. The refrigerator of claim 13, wherein the first detection temperature (Ht1) is a lowest
temperature value during a period of time when the heat generating element is turned
on,
wherein the second detection temperature (Ht2) is a highest temperature value during
a period of time when the heat generating element is turned on.
16. The refrigerator of claim 13, wherein the controller is configured to perform a defrosting
operation of the evaporator, when the temperature difference value between the first
sensing temperature (Ht1) and the second sensing temperature (Ht2) is less than a
first reference value,
17. The refrigerator of claim 16, wherein the controller is configured to update a temperature
difference value between the first detection temperature (Ht1) and the second detection
temperature (Ht2) after the defrosting operation is completed,
wherein failure of the sensor is displayed when the updated temperature difference
value exceeds a second reference value greater than the second reference value.
18. The refrigerator of claim 17, wherein the controller is configured to:
determine whether the updated temperature difference value is less than a third reference
value less than the second reference value when the updated temperature difference
value is less than the second reference value, and
display the clogging of the air passage in the heat-exchange space when the updated
temperature difference value exceeds the third reference value.
19. The refrigerator of claim 18, wherein the display of the clogging of the air passage
is at least one display of clogging of a cool air inflow hole of a cool air duck defining
the heat-exchange space, clogging of a cool air discharge hole of the cool air duck,
clogging of a blowing fan provided in the cool air duct or clogging of the bypass
passage.
20. The refrigerator of claim 18, wherein the controller is configured to:
determine whether the updated temperature difference value is less than a third reference
value less than the third reference value when the updated temperature difference
value is less than the third reference value, and
again perform the defrosting operation of the evaporator when the updated temperature
difference value is less than the fourth reference value.