U.S. patent application number 13/147924 was filed with the patent office on 2011-12-01 for control method of a refrigerator.
Invention is credited to Bong-Jun Choi, Su-Cheong Kim, Young-Geul Kim, Su-Won Lee, Yong-Joo Park, Gyu-Won Shin.
Application Number | 20110289945 13/147924 |
Document ID | / |
Family ID | 42562155 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110289945 |
Kind Code |
A1 |
Choi; Bong-Jun ; et
al. |
December 1, 2011 |
CONTROL METHOD OF A REFRIGERATOR
Abstract
An embodiment according to the present invention is to provide a
control method of a refrigerator that can operate a compressor
before a start of a defrost operation and during a predetermined
time to supply a high-temperature hot gas to an evaporator. With
the control method of the refrigerator according to the embodiments
of the refrigerator, the compressor is driven immediately before
the defrost operation and the blower fan cooling the compressor
stops, such that the high-temperature hot gas can be supplied to
the evaporator, thereby increasing the defrost efficiency.
Inventors: |
Choi; Bong-Jun; (Changwon
City, KR) ; Kim; Su-Cheong; (Changwon City, KR)
; Park; Yong-Joo; (Changwon City, KR) ; Shin;
Gyu-Won; (Changwon City, KR) ; Kim; Young-Geul;
(Changwon City, KR) ; Lee; Su-Won; (Changwon City,
KR) |
Family ID: |
42562155 |
Appl. No.: |
13/147924 |
Filed: |
January 28, 2010 |
PCT Filed: |
January 28, 2010 |
PCT NO: |
PCT/KR2010/000515 |
371 Date: |
August 4, 2011 |
Current U.S.
Class: |
62/80 |
Current CPC
Class: |
F25D 2323/0023 20130101;
F25D 2700/10 20130101; F25D 2700/12 20130101; F25D 17/062 20130101;
F25D 29/00 20130101; F25D 21/002 20130101; F25D 2400/02 20130101;
F25D 2600/02 20130101 |
Class at
Publication: |
62/80 |
International
Class: |
F25D 21/06 20060101
F25D021/06 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2009 |
KR |
10-2009-0010936 |
Claims
1. A control method of a refrigerator, comprising: a normal
operation step that is repeatedly turned-on/off by a compressor and
performs a normal freezing operation; an operation step before
defrost that is selectively performed according to whether a start
signal of a defrost operation is input and controls an turn-on/off
operation of a blower fan cooling the compressor according to
whether a temperature of the open air reaches a first setting
temperature before the start signal of the defrost operation is
input; and a defrost operation step that controls to bypass a
refrigerant discharged from the compressor to an evaporator by the
input of the start signal of the defrost operation and selectively
performs a high-temperature defrost operation or a low-temperature
defrost operation according to whether the open temperature reaches
a second setting temperature, wherein it returns to the normal
operation step after the defrost operation step is ended.
2. The control method of a refrigerator according to claim 1,
wherein the start signal of the defrost operation is periodically
input according to the set time interval and the operation step
before defrost is continuously performed until the start signal of
the defrost operation is input.
3. The control method of a refrigerator according to claim 1,
wherein the operation step before defrost controls the turn-on/off
of the blower fan according to whether the setting time before the
input of the start signal of the defrost operation passes.
4. The control method of a refrigerator according to claim 3,
wherein when the setting time does not pass, the blower fan is
turned-on, when the setting time passes, the blower fan is
controlled to be turned-on/off according to whether the temperature
of the open air reaches the first setting temperature.
5. The control method of a refrigerator according to claim 4,
wherein when the temperature of the open air is higher than the
first setting temperature, the blower fan is controlled to be
turned-on, and when the temperature of the open air is lower than
the first setting temperature, the blower fan is controlled to be
turned-off and the compressor is operated.
6. The control method of a refrigerator according to claim 1,
wherein the defrost operation step performs the high-temperature
defrost operation when the temperature of the open air is higher
than the second setting temperature and performs the
low-temperature defrost operation when the temperature of the open
air is lower than the second setting temperature.
7. The control method of a refrigerator according to claim 6,
wherein the rotation speed of the compressor at the
high-temperature defrost operation is formed to be higher than the
rotation speed of the compressor at the low-temperature defrost
operation.
8. The control method of a refrigerator according to claim 1,
wherein the high-temperature defrost operation and the
low-temperature defrost operation are selectively performed
according to whether the temperature of the evaporator is higher
than the third setting temperature.
9. The control method of a refrigerator according to claim 1,
wherein at the high-temperature defrost operation, the rotation
speed of the compressor is maintained for the predetermined time
after being linearly increased from the initial rotation speed to
the highest rotation speed and then linearly reduced.
10. The control method of a refrigerator according to claim 1,
wherein at the low-temperature defrost operation, the rotation
speed of the compressor is maintained until the defrost operation
is ended after being linearly increased from the initial rotation
speed to the highest rotation speed.
11. A control method of a refrigerator, comprising: a normal
operation step that generates cool air by a refrigerant circulating
a compressor, a condenser, an expander, and an evaporator; a
defrost operation step that periodically operates according to an
input of a start signal of the defrost operation and selectively
performs the defrost of the evaporator according to whether the
temperature of the evaporator reaches a third setting temperature;
and an operation step before defrost that is performed before the
defrost operation step and when a setting time does not pass before
the input of the start signal of the defrost operation, turns-on a
blower fan cooling the compressor and when the setting time passes,
controls the turn-on/off of the blower fan according to whether the
temperature of the open air is higher than the first setting
temperature.
12. The control method of a refrigerator according to claim 11,
wherein the defrost of the evaporator is simultaneously performed
with an operation of a defrost heater and the hot-gas defrost that
supplies the refrigerant from the discharge side of the compressor
to the inlet side of the evaporator.
13. The control method of a refrigerator according to claim 12,
wherein the compressor at the hot-gas defrost is decelerated at the
highest rotation speed at the instant that the refrigerant pressure
sucked into the inlet side of the evaporator exceeds a setting
pressure.
14. The control method of a refrigerator according to claim 11,
wherein at the defrost operation, the low-temperature defrost
operation that operates the compressor at low speed and the
high-temperature defrost operation that operates the compressor at
higher speed than the compressor of the low-temperature defrost
operation are selectively performed according to whether the
temperature of the open air is higher than a second setting
temperature.
15. The control method of a refrigerator according to claim 14,
wherein during the high-temperature defrost operation, the
compressor is sequentially operated at: a first period that is
increased from an initial rotation speed to a highest rotation
speed; a second period that maintains the highest rotation speed
during a predetermined period after reaching the highest rotation
speed; and a third period that is reduced from the highest rotation
speed to the lowest rotation speed; and a fourth period that
maintains the rotation speed until the defrost operation is ended
after reaching the lowest rotation speed.
16. The control method of a refrigerator according to claim 15,
wherein during the low-temperature defrost operation, the
compressor includes: a first period where is increased from an
initial rotation speed to a highest rotation speed; and a second
period that maintains the highest rotation speed during a
predetermined period after reaching the highest rotation speed,
when the temperature of the evaporator reaches the third setting
temperature, the voltage supplied to the compressor is turned-off.
Description
TECHNICAL FIELD
[0001] The embodiment relates to a control method of a
refrigerator.
BACKGROUND ART
[0002] Generally, a refrigerator is consumer electronics that can
store food at low temperature in an inner storage space shielded by
a door. The refrigerator uses cool air generated by heat exchange
with a refrigerant circulating a freezing cycle to cool the storage
space, such that it is configured to store the stored food at an
optimum state.
[0003] The refrigerator includes an evaporator that generates cool
air. Frost may be generated in the evaporator by the frosting and
freezing of moisture.
[0004] When frost is generated in the evaporator, a problem of
sanitation may occur and cooling efficiency is degraded to increase
power consumption. In order to prevent the problem, the
refrigerator includes a defrost heater to remove frost
(hereinafter, referred to as defrost).
[0005] At a step of a defrost operation, the defrost heater is
operated and an operation of components that configure a freezing
cycle such as a compressor and a blower fan stops. The defrost
operation can be continued during a setting temperature or until a
temperature of the refrigerator reaches the setting
temperature.
[0006] Meanwhile, the defrost operation can be repeatedly performed
in consideration of an open and close frequency, an open and close
accumulative time, an operation ratio of the compressor, etc.
[0007] The defrost operation of the related art is performed by a
method that heats a high-temperature refrigerant by the defrost
heater or a method that bypasses the high-temperature refrigerant
discharged from the compressor to the evaporator side by a
switching valve and heats it with a hot gas. Two methods can be
simultaneously adopted as needed.
[0008] According to the methods of the related art, the temperature
in the refrigerator is increased during the defrost operation, such
that food is damaged.
DISCLOSURE OF INVENTION
Technical Problem
[0009] An embodiment according to the present invention is to
provide a control method of a refrigerator that can operate a
compressor before a start of a defrost operation and during a
predetermined time to supply a high-temperature hot gas to an
evaporator.
[0010] In addition, the present invention is to provide a control
method of a refrigerator that can vary a rotation speed of a
compressor according to a temperature of the open air during a
defrost operation.
Solution to Problem
[0011] There is provided a control method of a refrigerator
according to an embodiment of the present invention, including: a
normal operation step that is repeatedly turned-on/off by a
compressor and performs a normal freezing operation; an operation
step before defrost that is selectively performed according to
whether a start signal of a defrost operation is input and controls
an turn-on/off operation of a blower fan cooling the compressor
according to whether a temperature of the open air reaches a first
setting temperature before the start signal of the defrost
operation is input; and a defrost operation step that controls to
bypass a refrigerant discharged from the compressor to an
evaporator side by the input of the start signal of the defrost
operation and selectively performs a high-temperature defrost
operation or a low-temperature defrost operation according to
whether the open temperature reaches a second setting temperature,
wherein it returns to the normal operation step after the defrost
operation step is ended.
[0012] There is provided a control method of a refrigerator
according to another embodiment of the present invention,
including: a normal operation step that generates cool air by a
refrigerant circulating a compressor, a condenser, an expander, and
an evaporator; a defrost operation step that periodically operates
according to an input of a start signal of the defrost operation
and selectively performs the defrost of the evaporator according to
whether the temperature of the evaporator side reaches a third
setting temperature; and an operation step before defrost that is
performed before the defrost operation step and when a setting time
does not pass before the input of the start signal of the defrost
operation, turns-on a blower fan cooling the compressor and when
the setting time passes, controls the turn-on/off of the blower fan
according to whether the temperature of the open air is higher than
the first setting temperature.
Advantageous Effects of Invention
[0013] With the control method of the refrigerator according to the
embodiments of the refrigerator, the compressor is operated
immediately before the defrost operation and the blower fan cooling
the compressor stops, such that the high-temperature hot gas can be
supplied to the evaporator, thereby increasing the defrost
efficiency.
[0014] In addition, the refrigerant, which is discharged from the
compressor and is supplied to the evaporator, can be supplied to
the refrigerator before the defrost operation, thereby preventing
the temperature in the refrigerator from suddenly increasing during
the defrost operation.
[0015] Further, the rotation speed can be varied according to the
temperature of the open air during the defrost operation, such that
the high-temperature hot gas can be discharged even when the
temperature of the open air is lower than the setting
temperature.
[0016] Consequently, when the temperature of the open air is lower
than the setting temperature, the defrost stuck in the evaporator
can be smoothly removed by the high-temperature hot gas discharged
from the compressor, thereby making it possible to increase the
defrost efficiency.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a cycle diagram showing a configuration of a
refrigerator cycle of a refrigerator according to an embodiment of
the present invention;
[0018] FIG. 2 is a block diagram showing a configuration of a
refrigerator according to an embodiment of the present
invention;
[0019] FIG. 3 is a flowchart showing a control method of a
refrigerator according to an embodiment of the present
invention;
[0020] FIG. 4 is a flow chart showing an operation method before
defrost among the control methods of the refrigerator according to
the embodiment of the present invention;
[0021] FIG. 5 is a flow chart showing an operation method before
defrost among the control methods of the refrigerator according to
the embodiment of the present invention;
[0022] FIG. 6 is a graph showing a change in input voltage
according to a time during a high-temperature defrost operation
with reference to the control method of the refrigerator according
to the embodiment of the present invention; and
[0023] FIG. 7 is a graph showing a change in input voltage
according to a time during a low-temperature defrost operation with
reference to the control method of the refrigerator according to
the embodiment of the present invention.
MODE FOR THE INVENTION
[0024] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings that
form a part hereof, and in which is shown by way of illustration
specific preferred embodiments in which the invention may be
practiced. These embodiments are described in sufficient detail to
enable those skilled in the art to practice the invention, and it
is understood that other embodiments may be utilized and that
logical structural, mechanical, electrical, and chemical changes
may be made without departing from the spirit or scope of the
invention. To avoid detail not necessary to enable those skilled in
the art to practice the invention, the description may omit certain
information known to those skilled in the art. The following
detailed description is, therefore, not to be taken in a limiting
sense, and the scope of the present invention is defined only by
the appended claims.
[0025] FIG. 1 is a cycle diagram showing a configuration of a
refrigerator cycle of a refrigerator according to an embodiment of
the present invention and FIG. 2 is a block diagram showing a
configuration of a refrigerator according to an embodiment of the
present invention.
[0026] Referring to FIGS. 1 and 2, a compressor 10, a condenser 20,
an expander 30, an evaporator 40, and a liquid refrigerant tank 50,
which configures a freezing cycle, are sequentially connected in
series in a refrigerator 1 according to an embodiment of the
present invention to circulate the refrigerant, thereby making it
possible to operate the freezing cycle.
[0027] The refrigerator 1 further includes a bypass pipe 60 that
bypasses the refrigerant discharged from the compressor 10 to an
inlet side of the evaporator 40.
[0028] A switching valve 70, which is connected to a pipe
connecting the compressor 10 and the condenser 20, is provided at
one end of the bypass pipe 60.
[0029] The switching valve 70 selectively branches a
high-temperature and high-pressure refrigerant discharged from an
outlet side of the compressor 10 to the condenser 20 or the
evaporator 40. The switching valve 70 is configured to connect to
the compressor 10, the condenser 20, and the bypass pipe 60,
respectively.
[0030] The blower fan 11 cooling the compressor 10 is provided at
one side of the compressor 10. The blower fan 11 is configured to
cool the compressor 10 while rotating together with the operation
of the compressor 10 during the normal operation of the
refrigerator 1.
[0031] The blower fan 11 blows the open air to the condenser 20
side, such that the heat exchange can be easily performed in the
condenser 20.
[0032] One side of the evaporator 40 is provided with a cooling fan
41 that forcibly blows a refrigerant generated by the heat exchange
with the refrigerant in the evaporator 40 to the refrigerator
side.
[0033] One side of the evaporator 40 is provided with a defrost
heater 80 that is heated during the defrost operation of the
refrigerator 1 and removes frost stuck in the evaporator 40.
[0034] The refrigerator 1 is further provided with a first
temperature sensor 91 that senses the temperature of the evaporator
40 and a second temperature sensor 92 that senses the temperature
of the open air.
[0035] The first temperature sensor 91 may be disposed at one side
of the evaporator 40 and the second temperature sensor 92 may be
disposed at one side of a machine room or a main body of the
refrigerator in which the compressor 10 and the condenser 20 are
provided.
[0036] In addition, the refrigerator 1 includes a counter 90 that
counts an operation time of a plurality of components configuring
the refrigerator and a controller 100 that receives a signal from
the first and second temperature sensors 91 and 92 and the counter
90 to control the operation of the compressor 10, the blower fan
11, the cooling fan 41, and the defrost heater 80, etc.
[0037] Hereinafter, the control method of the refrigerator
according to the embodiment of the present invention having the
above-mentioned configuration will be described in detail with
reference to the accompanying drawings.
[0038] FIG. 3 is a flowchart showing a control method of a
refrigerator according to the embodiment of the present invention,
FIG. 4 is a flow chart showing an operation method before defrost
among the control methods of the refrigerator according to the
embodiment of the present invention, and FIG. 5 is a flow chart
showing an operation method before defrost among the control
methods of the refrigerator according to the embodiment of the
present invention.
[0039] Referring to FIGS. 3 to 5, under the normal operation
environment of the refrigerator 1, when the compressor 10 is
operated, the refrigerator is circulated and the blower fan 11, the
cooling fan 41, etc., can be controlled.
[0040] The rotating speed of the compressor 10 can be controlled
according to an input load. To this end, the compressor 10 may
include an inverter-type compressor of which the number of
rotations can be changed according to the input voltage.
[0041] The operation time of the compressor 10 can be controlled
according to the input load. In detail, after the temperature of
the refrigerator reaches a predetermined level or the compressor 10
is operated during a setting time or more, the compressor 10 is
operated again after it stops during a predetermined period. The
above process is continuously repeated (S100).
[0042] Moisture of the open air can be stuck on a surface of the
evaporator 40 during the general normal operations and thus, frost
may occur. Frost can be generated on the surface of the evaporator
40 by the moisture of food that is stored in the refrigerator.
[0043] The surface temperature is lowered by the continuous
operation of the freezing cycle, such that the frost stuck on the
surface of the evaporator 40 is frozen and continuously grown. As a
result, the heat exchange performance of the evaporator 40 is
degraded and the freezing performance of the refrigerator is
degraded.
[0044] Therefore, in order to prevent this, the defrost operation
is needed to remove the frost frozen in the evaporator 40.
[0045] The defrost operation may increase the temperature of the
refrigerator, such that it may be performed at a predetermined
period to maintain the storage performance.
[0046] The accumulative operation time of the compressor 10, the
open frequency of the door, and the open accumulative time of the
door, etc, can be counted in the counter 90 and the timing of the
defrost operation can be determined based on the counted time.
[0047] The defrost operation starts by the start signal of the
defrost operation output from the controller 110 and the start
signal of the defrost operation can be output at a timing that
needs the defrost operation according to a predetermined period in
the process of performing the normal operation (S100).
[0048] During the defrost operation using the hot gas of the
compressor, the operation of the blower fan 11 that cools the
compressor 11 can stop in order to secure the temperature (high
temperature) of the hot gas supplied to the evaporator 40.
[0049] Meanwhile, in order to increase the efficiency of the
defrost operation, the operation before defrost can be performed
before the defrost operation is performed (S200).
[0050] The operation before defrost includes a defrost signal input
determining step (S210) that confirms whether the start signal of
the defrost operation is input during the performance of the normal
operation.
[0051] When the start signal of the defrost operation is input, the
defrost operation is performed and when the start signal of the
defrost operation is not input, it is determined whether the
defrost operation passes the setting time T from the time when the
defrost operation is performed. For example, the setting time T can
be set to approximately 30 minutes in consideration of the defrost
efficiency. In other words, the setting time T can be set to 30
minutes before a time when the defrost operation starts to perform
(S220).
[0052] In other words, when it is assumed that the defrost
operation is performed at a period of 10 hours, it is determined
whether the setting time reaches a time when about one and a half
hours passes after the start signal of the previous defrost
operation is input.
[0053] Meanwhile, when it does not pass the setting time T before
the start signal of the defrost operation is input at the setting
time determining step (S220), the blower fan 11 maintains a turn-on
state during the operation of the compressor 10.
[0054] The blower fan 11 performs a normal operation until it
passes the setting time before the time when the start signal of
the defrost operation is input. In other words, since the blower
fan 11 does not reach a specific time before the defrost operation,
it does not have to be turned-off in order to perform the defrost
operation (S230).
[0055] On the other hand, if it is determined at the setting time
determining step (S220) that the setting time T before the start
signal of the defrost operation is input passes, a setting
temperature determining step, which compares the temperature of the
open air detected by the second temperature sensor 92 with the
first setting temperature D1, is performed (S240).
[0056] At this time, the first setting temperature D1 can be set to
approximately 15.degree. C. When the temperature of the open air is
higher than about 15.degree. C., the temperature of the hot gas
necessary for the normal frost can be secured even though the
blower fan 11 does not stop.
[0057] Therefore, when the temperature of the open air detected by
the second temperature sensor 92 is higher than the first setting
temperature D1, the blower fan 11 maintains a turn-on state during
the operation of the compressor 10 (S230) and performs the normal
operation until it reaches the setting time T before the start
signal of the defrost operation is input (S100).
[0058] On the other hand, when the temperature of the open air
detected by the second temperature sensor 92 is lower than the
first setting temperature D1, the compressor 10 is in a turn-on
state to be operated and the blower fan 11 stops (S250).
[0059] In this case, the force cooling of the compressor 10 is not
performed and the refrigerant discharged from the compressor 10 is
in a higher-temperature state. The operation state can be
maintained during the setting time.
[0060] In other words, when the temperature of the open air is
lower than the first setting temperature D1, the operation of the
blower fan 11 stops when the compressor 10 is operated before the
setting time T of the time when the defrost operation starts.
[0061] In this case, the temperature of the refrigerant discharged
from the compressor 10 can be increased and the more efficient
defrost can be performed at the time when the defrost operation
starts.
[0062] The cool air can be supplied to the refrigerator by the
operation of the compressor 10 before the defrost operation, such
that the sudden increase in the temperature of the refrigerator can
be prevented during the defrost operation [operation step before
defrost (S200)].
[0063] Meanwhile, when the start signal of the defrost operation is
input from the controller 100, the defrost operation starts. When
the start signal of the defrost operation is input, the temperature
of the open air detected by the second temperature sensor 92 is
compared with the second setting temperature D2.
[0064] When the detected temperature of the open air is higher than
the second setting temperature D2, the high-temperature defrost
operation is performed and when the detected temperature of the
open air is lower than the second setting temperature D2, the
low-temperature defrost operation is performed.
[0065] At this time, the second setting temperature D2, which is a
reference of differentiating the high-temperature defrost operation
and the low-temperature defrost operation, can be set to about
3.degree. C.
[0066] When the temperature of the open air is lower than 3.degree.
C., the defrost efficiency cannot but degrade as compared with the
case where the temperature of the open air is relatively high.
Therefore, in order to maintain the appropriate defrost efficiency
according to the temperature of the open air, the scheme of the
defrost operation is divided on the second setting temperature D2
and performed (S310).
[0067] First, in the case of the high-temperature defrost operation
where the temperature of the open air is higher than the second
setting temperature D2, the compressor 10, the blower fan 11, and
the cooling fan 41 stop (S311 and S312).
[0068] It is determined that the temperature of the evaporator 40
reaches the third setting temperature D3 by the first temperature
sensor 91.
[0069] The third setting temperature D3 can be set to about
3.degree. C. It can be determined that the defrost is performed
when the temperature of the evaporator 40 side is approximately
3.degree. C. On the other hand, when the temperature of the
evaporator 40 side is lower than approximately 3.degree. C., the
defrost operation is continuously performed (S320).
[0070] Herein, in the defrost operation, the defrost scheme by the
defrost heater 80 and the defrost scheme by the hot gas can be
simultaneously performed.
[0071] In detail, when the temperature of the evaporator 40 side is
lower than the third setting temperature (at steps S311 and S312,
the operations of the compressor 10, the cooling fan 41, and the
blower fan 11 are turned-off, the temperature of the evaporator 40
side is in a sub-zero state), the defrost heater 80 is
turned-on.
[0072] The switching valve 70 is switched to flow the refrigerant
from the outlet of the compressor 10 to the inlet of the evaporator
40 and the compressor can be operated at a low speed.
[0073] Since the temperature of the open air is in the higher state
than the second setting temperature D2, the refrigerant for defrost
can be supplied to the evaporator 40 side even though the
compressor 10 is operated at a low speed. Herein, low speed" can be
defined as forming low speed as compared to the operation of the
compressor at step S343.
[0074] The high-temperature and high-pressure refrigerant (hot gas)
discharged from the compressor 10 is guided to the evaporator 40
through the bypass pipe 60. The hot gas is filled in the evaporator
40 such that the surface of the evaporator 40 can be heated and the
removal of the frost frozen on the surface of the evaporator 40
starts.
[0075] Meanwhile, after the switching valve 70 is switched, the
compressor 10 can be operated after approximately 5 seconds passes.
The switching valve 70 and the entire system can be protected by
supplying the high-temperature and high-pressure refrigerant by the
compressor 10 at a time difference with the switching of the
switching valve 70.
[0076] The defrost heater 80 can be operated immediately before and
after the switching of the refrigerant flow path by the operation
of the switching valve 70. In particular, at the early time when
the defrost is performed, the evaporator 40 or a portion adjacent
the evaporator 40 is heated at higher heat, such that the defrost
heater 80 is operated, thereby making it possible to more rapidly
perform the defrost.
[0077] Meanwhile, the above-mentioned defrost operation is
repeatedly performed until the temperature detected by the first
temperature sensor 91 is higher than the third setting temperature
D3 (S321, S322, and S323).
[0078] When the temperature detected by the first temperature
sensor 91 is higher than the third setting temperature D3, the
high-temperature defrost operation is ended. In other words, the
operations of the compressor 10 and the defrost heater 80 stop and
the switching is performed by the switching valve 80.
[0079] The refrigerant discharged from the compressor 10 again
flows to the condenser 20 according to the switching of the
switching valve 70 (S324, S325, S326).
[0080] The freezing cycle is in the normal operation state by the
path change of the switching valve 70 and returns to the normal
operation step (S100) that performs the general normal operation
again after ending the high-temperature defrost operation [defrost
operation step (S300)].
[0081] Meanwhile, in the case of the low-temperature defrost
operation where the temperature of the open air is higher than the
second setting temperature D2, the compressor 10, the blower fan
11, and the cooling fan 41 stop (S331 and S332).
[0082] It is determined that the temperature of the evaporator 40
side reaches the third setting temperature D3 by the first
temperature sensor 91.
[0083] The third setting temperature D3 can be set to about
3.degree. C. It can be determined that the defrost is performed
when the temperature of the evaporator 40 side is approximately
3.degree. C. On the other hand, when the temperature of the
evaporator 40 side is lower than approximately 3.degree. C., the
defrost operation is continuously performed (S340).
[0084] In detail, when the temperature of the evaporator 40 side is
lower than the third setting temperature (at steps S331 and S332,
the operations of the compressor 10, the cooling fan 41, and the
blower fan 11 are turned-off, the temperature of the evaporator 40
is in a sub-zero state), the defrost heater 80 is turned-on.
[0085] The switching valve 70 is switched to flow the refrigerant
from the outlet of the compressor 10 to the inlet of the evaporator
40 and the compressor can be operated at a high speed. In other
words, the defrost scheme by the defrost heater 80 and the defrost
scheme by the hot gas can be simultaneously performed.
[0086] Since the temperature of the open air is in the lower state
than the second setting temperature D2, the compressor 10 is
operated at a high speed, such that a large amount of refrigerant
necessary for defrost can be supplied to the evaporator 40
side.
[0087] The high-temperature and high-pressure refrigerant (hot gas)
discharged from the compressor 10 is guided to the evaporator 40
through the bypass pipe 60 and the surface of the evaporator 40 is
heated, thereby making it possible to remove the frost.
[0088] The defrost heater 80 can be operated immediately before and
after the switching of the refrigerant flow path by the operation
of the switching valve 70. In particular, it can be controlled to
supply a large heat amount at the early time when the defrost is
performed.
[0089] Meanwhile, the above-mentioned defrost operation is
repeatedly performed until the temperature detected by the first
temperature sensor 91 is higher than the third setting temperature
D3 (S341, S342, and S343).
[0090] When the temperature detected by the first temperature
sensor 91 is higher than the third setting temperature D3, the
low-temperature defrost operation is ended. In other words, the
operations of the compressor 10 and the defrost heater 80 stop and
the switching is performed by the switching valve 80.
[0091] The refrigerant discharged from the compressor 10 again
flows to the condenser 20 according to the switching of the
switching valve 70 (S344, S345, and S346).
[0092] FIG. 6 is a graph showing a change in input voltage
according to a time during a high-temperature defrost operation
with reference to the control method of the refrigerator according
to the embodiment of the present invention.
[0093] Referring to FIG. 6, the compressor 10 is operated to
sequentially pass a first period, a second period, a third period,
and a fourth period during the high-temperature defrost operation
and the change in the operation speed (rotation speed) and rotation
speed of the compressor 10 is controlled differently at each
period.
[0094] In detail, when power is applied to the compressor 10, an
initial input voltage of the compressor 10 is set to Vo at the
first period. A magnitude of Vo may be 120V (rms).
[0095] The compressor 10 continuously (linearly) increases the
input voltage for approximately t1, which reaches V1. Herein, t1,
which is a time that is previously set, may be approximately 6
seconds.
[0096] The size of V1 may be 130V (rms) and may correspond to the
highest rotation speed during the high-temperature defrost
operation.
[0097] The voltage input to the compressor 10 is maintained to
approximately t2 as the magnitude of V1 at the second period.
Herein, t2, which is a time that is previously set, may be
approximately 3 minutes.
[0098] Consequently, the compressor 10 continuously increases the
input voltage after the operation and maintains the highest
rotation speed (input voltage V1) for the previously set time t1 to
t2.
[0099] The temperature of the refrigerant discharged from the
compressor 10 is increased in the state where the highest rotation
speed is maintained, such that the defrost can be efficiently
performed.
[0100] However, when the compressor 10 maintains the highest
rotation speed (input voltage V1) for a long time, the pressure of
the refrigerant discharged from the compressor 10 increases and the
pressure of the suction side of the evaporator 40 increases,
thereby generating noise.
[0101] Therefore, it controls to lower the rotation speed of the
compressor 10 after passing approximate t2 that is a threshold
value of a noise allowable level. In other words, the rotation
speed of the compressor 10 is reduced at the highest rotation speed
at the instant that the pressure of the refrigerant sucked into the
evaporator 40 side exceeds the setting pressure.
[0102] In order to prevent the noise of the compressor at the third
period, the rotation speed of the compressor 10 is gradually
(linearly) lowered from the highest rotation speed (input voltage
V1).
[0103] In detail, the input voltage of the compressor 10 is
continuously reduced at V1 and the input voltage may be V2 at the
time that passes t3 from the start time of the defrost operation.
Herein, t3, which is a previously set time, may be set to
approximately 14 minutes after the operation of the compressor and
V2 is a predetermined time and may be set to approximately 100V
(rms).
[0104] As the rotation speed of the compressor 10 is reduced, the
pressure of the refrigerant discharged from the compressor 10 and
the pressure of the suction side of the evaporator 40 are reduced,
thereby reducing the noise.
[0105] In summary, the rotation speed of the compressor 10 is
controlled in the patterns Vo to V2 shown in FIG. 6, the
temperature level of the hot gas discharged from the compressor 10
can be maintained in an allowable range, thereby making it possible
to prevent the noise of the compressor 10.
[0106] At the fourth period, the input voltage of the compressor 10
is maintained at V2. At this time, the defrost operation is
performed.
[0107] The rotation speed of the compressor 10 may be maintained at
the lowest rotation speed (input voltage V2) up to a time (t4) when
the defrost operation is ended. The condition where the defrost
operation is ended is that the temperature of the evaporator 40
reaches the third setting temperature D3 as shown in FIG. 5.
[0108] The input voltage supplied to the compressor 10 together
with the ending of the defrost operation is turned-off and the
compressor 10 stops.
[0109] As described above, the rotation speed (input voltage Vo to
V2) of the compressor 10 is proposed as one embodiment and may be
proposed as other previously set values according to and the
defrost heat amount and the capacity of the compressor 10.
[0110] FIG. 7 is a graph showing a change in input voltage
according to a time during a low-temperature defrost operation with
reference to the control method of the refrigerator according to
the embodiment of the present invention.
[0111] FIG. 7 shows the change in the input voltage of the
compressor 10, that is, the change in the input voltage at the
first period and the second period according to the change in time
during the low-temperature defrost operation.
[0112] Referring to FIG. 7, the compressor 10 is rotated at an
initial rotation speed (initial input voltage V0 ) by the voltage
input to the compressor 10 while the low-temperature defrost
operation is performed. Herein, the initial input voltage may be
set to 120V (rms).
[0113] The input voltage applied to the compressor 10 is
continuously (linearly) increased to a time t5 that is previously
set at the first period. Herein, the time t5 may be approximately
20 seconds after the operation of the compressor 10.
[0114] After t5 passes, the compressor 10 can be rotated at the
highest rotation speed (input voltage V3). Herein, V3, which is a
previously set value, may be set to approximately 180V (rms).
[0115] The compressor 10 is rotated at a relatively high speed by
V3, that is, the input voltage of 180V (rms) (comparing with V1 of
FIG. 6), thereby making it possible to discharge the relatively
higher-temperature and higher-pressure refrigerant than the
refrigerant temperature during the high-temperature defrost
operation.
[0116] Even though the high-temperature and high-pressure
refrigerant is discharged from the compressor 10, the
low-temperature defrost operation is performed at the state where
the temperature of the open air is low, such that the pressure of
the suction side of the evaporator 40 is relatively lower, thereby
reducing the noise.
[0117] The rotation speed of the compressor 10 is constantly
maintained after it reaches the highest rotation speed (input
voltage V3) at the second period. When the temperature of the
evaporator 40 is approximately 3.degree. C. that is the third
setting temperature D3, the supply of voltage to the compressor 10
stops at time t6 and the operation of the compressor 10 stops.
[0118] In summary, the voltage input to the compressor 10 is
increased from the first Vo to V3 during the low-temperature
defrost operation and the rotation speed of the compressor 10
maintains the highest rotation speed V3 for a predetermined
time.
[0119] When the ending condition of the low-temperature defrost
operation is satisfied, that is, the temperature of the evaporator
40 reaches the third setting temperature (third setting temperature
or more), the voltage supplied to the compressor 10 is turned-off
and the operation of the compressor 10 stops.
[0120] As described above, the operation of the blower fan 11 is
controlled according to the temperature value of the open air of
the refrigerator, such that the freezing cycle can be efficiently
operated.
[0121] In addition, the high-temperature defrost operation and the
low-temperature defrost operation can be selectively performed
according the temperature value of the open air, such that the
defrost of the evaporator 40 can be efficiently performed.
[0122] Further, the defrost heater 80 and the hot-gas defrost
operation can be simultaneously performed according to the
temperature value of the evaporator 40, such that the defrost
efficiency can be increased.
INDUSTRIAL APPLICABILITY
[0123] With the control method of a refrigerator according to the
embodiment as constituted above, a compressor is operated
immediately before the defrost operation and the blower fan cooling
the compressor stops, such that the high-temperature hot gas can be
supplied to the evaporator, thereby increasing the defrost
efficiency. Therefore, its industrial applicability is
noticeable.
* * * * *