U.S. patent application number 12/659118 was filed with the patent office on 2010-11-04 for washing machine and method for controlling the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Myung Sun Kang, Jae Hong Kim, Sung Jin Kim, Hong Seok Ko, Sang Up Lee, Sang Yeon Pyo.
Application Number | 20100275381 12/659118 |
Document ID | / |
Family ID | 43018806 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100275381 |
Kind Code |
A1 |
Ko; Hong Seok ; et
al. |
November 4, 2010 |
Washing machine and method for controlling the same
Abstract
A washing machine and a method of controlling the same are
disclosed. If two washing tubs simultaneously perform the
dehydration, unbalanced positions of the first and second washing
tubs are checked. The method controls dehydration rotation speed or
dehydration rotation direction of each washing tub to adjust a
difference in unbalanced position angle between two washing tubs,
thereby reducing vibration. If dehydration is performed in one
washing tub, the method prevents the other washing tub performing
no dehydration process from entering the dehydration process.
Inventors: |
Ko; Hong Seok; (Yongin-si,
KR) ; Kim; Jae Hong; (Suwon-si, KR) ; Kang;
Myung Sun; (Suwon-si, KR) ; Pyo; Sang Yeon;
(Suwon-si, KR) ; Lee; Sang Up; (Yongin-si, KR)
; Kim; Sung Jin; (Seongnam-si, KR) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700, 1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
43018806 |
Appl. No.: |
12/659118 |
Filed: |
February 25, 2010 |
Current U.S.
Class: |
8/137 ;
68/23.1 |
Current CPC
Class: |
D06F 33/00 20130101;
D06F 35/005 20130101; D06F 31/00 20130101; D06F 35/007
20130101 |
Class at
Publication: |
8/137 ;
68/23.1 |
International
Class: |
D06F 35/00 20060101
D06F035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 29, 2009 |
KR |
10-2009-37412 |
Claims
1. A method of controlling a washing machine having a first washing
tub and a second washing tub, the method comprising: determining
whether a dehydration operation is performed in the first and
second washing tubs; and reducing vibration of the washing machine
comprising adjusting the dehydration operation of the first or
second washing tub.
2. The method according to claim 1, wherein the determining whether
the dehydration operation is performed in the first and second
washing tubs includes: determining, when one of the first and
second washing tubs is in the dehydration process, whether the
other of the first and second washing tubs performing no
dehydration operation begins a dehydration operation.
3. The method according to claim 2, further comprising:
controlling, if the other of the first and second washing tubs
having no dehydration operation beings the dehydration operation,
the dehydration operation of the other of the first and second
washing tubs comprising performing a dehydration rotation in a
direction opposite to a dehydration rotation direction of the one
of the first and second washing tubs in which the dehydration
operation is performed.
4. The method according to claim 2, further comprising:
controlling, if the other of the first and second washing tubs
having no dehydration operation begins the dehydration operation, a
dehydration operation of the other of the first and second washing
tubs to prevent the other of the first and second washing tubs from
entering the dehydration operation until the washing tub performing
the dehydration operation stops the dehydration operation.
5. The method according to claim 1, wherein the determining whether
the dehydration process is performed in the first and second
washing tubs includes: determining whether the first and second
washing tubs simultaneously begin the dehydration operation.
6. The method according to claim 5, further comprising: setting, if
the first and second washing tubs simultaneously begin the
dehydration operation, different dehydration rotation directions,
so that the dehydration operations of the first and second washing
tubs are performed in different directions.
7. The method according to claim 5, further comprising: adjusting,
if the first and second washing tubs simultaneously begin the
dehydration operation, a dehydration operation of the washing tub
in such a manner that the dehydration operation is performed only
in one of the first and second washing tubs.
8. The method according to claim 7, further comprising: adjusting a
dehydration operation of the washing tub having no dehydration
operation in such a manner that the washing tub having no
dehydrating operation begins the dehydration operation when the
dehydration operation of the washing tub having the dehydration
operation is completed.
9. The method according to claim 1, wherein the determining whether
the dehydration process is performed in the first and second
washing tubs includes: determining whether the first and second
washing tubs simultaneously perform the dehydration operation.
10. The method according to claim 9, further comprising: checking
an unbalanced position of each of the first and second washing tubs
when the first and second washing tubs simultaneously perform the
dehydration operation.
11. The method according to claim 10, wherein: a first drum is
rotatably installed in the first washing tub, and a second drum is
rotatably installed in the second washing tub, and the checking of
the unbalanced position comprises detecting a rotation speed of the
first or second drum.
12. The method according to claim 11, wherein the checking of the
unbalanced position by detecting the rotation speed of the first or
second drum includes: checking a position at which a rotational
acceleration of the first or second drum becomes zero.
13. The method according to claim 12, wherein the checking of the
unbalanced position by detecting the rotation speed of the first or
second drum further includes: determining that the unbalanced
position is at a highest point of the first or second drum at a
time at which the rotational acceleration becomes zero in response
to an increasing and decreasing of the rotation speed of the first
or second drum.
14. The method according to claim 13, wherein the checking of the
unbalanced position by detecting the rotation speed of the first or
second drum further includes: determining that the unbalanced
position is at a lowest point of the first or second drum at a time
at which the rotation acceleration becomes zero in response to the
increasing and decreasing of the rotation speed of the first or
second drum.
15. The method according to claim 10, further comprising:
adjusting, if the unbalanced position of the first or second
washing tub is checked, an unbalanced position of the first or
second washing tub, and reducing the vibration of the washing
machine.
16. The method according to claim 15, wherein the adjusting of the
unbalanced position of the first or second washing tub includes:
controlling a difference between a first position angle of an
unbalance of the first washing tub and a second position angle of
an unbalance of the second washing tub to be equal to or larger
than a reference angle.
17. The method according to claim 15, wherein the adjusting of the
unbalanced position of the first or second washing tub includes:
adjusting the unbalanced position comprising adjusting a
dehydration rotation speed of the first or second washing tub.
18. The method according to claim 9, further comprising: setting,
if the dehydration operation is simultaneously performed in the
first and second washing tubs, different dehydration rotation
directions to the first and second washing tubs, and adjusting the
dehydration operations of each of the washing tubs.
19. The method according to claim 18, further comprising: checking
dehydration rotation speeds of the first and second washing tubs;
and changing the rotation direction of the washing tub having a
relatively slow dehydration rotation speed from among the first and
second washing tubs to another rotation direction, and adjusting
the dehydration operation of the washing tub in the changed
rotation direction.
20. A washing machine comprising: a plurality of washing tubs; and
a controller which checks whether a dehydration operation is
performed in each of the washing tubs, adjusts the dehydration
operation of each of the washing tubs when the dehydration
operation is performed in each of the washing tubs, and reduces a
vibration of the washing machine.
21. The washing machine according to claim 20, further comprising a
first drum and a second drum wherein: the plurality of washing tubs
include a first washing tub in which the first drum is rotatably
installed and a second washing tub in which the second drum is
rotatably installed, and the controller reduces vibration of the
washing machine by adjusting rotation operations of the first and
second drums.
22. The washing machine according to claim 21, further comprising:
a speed detector to detect a speed of the first or second drum.
23. The washing machine according to claim 22, wherein the
controller checks an unbalanced position of the first or second
washing tub according to a speed of the first or second drum.
24. The washing machine according to claim 23, wherein the
controller reduces vibration of the washing machine by adjusting
the unbalanced position of the first or second washing tub.
25. The washing machine according to claim 24, wherein the
controller adjusts a difference in the unbalanced position between
the first washing tub and the second washing tub to be equal to or
larger than a reference angle.
26. The washing machine according to claim 21, wherein the
controller reduces the vibration of the washing machine by
controlling the first and second drums to have different
dehydration rotation directions opposite to each other.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 2009-0037412, filed on Apr. 29, 2009 in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] Embodiments of the present invention relate to a washing
machine having a plurality of washing tubs to clean laundry in
different ways based on capacity and types of clothing, and a
method of controlling the same.
[0004] 2. Description of the Related Art
[0005] Generally, a washing machine (for example, a drum washing
machine) includes a single washing tub, and separates pollutants or
contaminants from dirty laundry using water and detergent. The
washing machine washes or cleans the dirty laundry using a series
of processes, i.e., a washing process to separate a pollutant or
contaminant from laundry with water containing a detergent, a
rinsing process to rinse bubbles or residual detergent out of the
laundry with clean water (specifically, rinsing water), and a
dehydration process to dehydrate the laundry at high speed.
[0006] In recent times, a drying function has been added to the
washing machine, so that the washing machine can perform a drying
process to dry dehydrated laundry. However, because clothing
generally has different kinds and different material qualities, the
washing machine may have difficulty in simultaneously cleaning all
the laundry contained in one washing tub using one washing course.
The washing machine including one washing tub separates some
clothing, which cannot be simultaneously cleaned, from other
clothing capable of being simultaneously cleaned. Thus, the
separated clothing requires additional washing. In this case, a
user suffers substantial inconvenience when using the washing
machine because a separate washing operation is needed for some
clothing, and the user has to drive the washing machine several
times (e.g., twice), so that time and energy may be excessively
consumed. Although the user wants to wash or clean only a small
amount of clothing, if a washing tub is a large-capacity washing
tub, the small amount of clothing must be washed or cleaned in the
large-capacity washing tub, resulting in unnecessary power
consumption.
SUMMARY
[0007] Therefore, it is an aspect of the present invention to
provide a method of reducing vibration of a washing machine by
adjusting unbalanced positions of two washing tubs contained in the
washing machine operating in a dehydration process.
[0008] It is another aspect of the present invention to provide a
method of controlling a dehydration rotation direction and a
dehydration-process entry or non-entry status during a dehydration
process of the washing machine having two washing tubs, thereby
reducing vibration of the washing machine.
[0009] Additional aspects of the invention will be set forth in
part in the description which follows and, in part, will be
apparent from the description, or may be learned by practice of the
invention.
[0010] The foregoing and/or other aspects of the present invention
may be achieved by providing a method of controlling a washing
machine having a first washing tub and a second washing tub, the
method including determining whether a dehydration operation is
performed in the first and second washing tubs; and reducing
vibration of the washing machine comprising adjusting the
dehydration operation of the first or second washing tub.
[0011] The determining whether the dehydration operation is
performed in the first and second washing tubs may include:
determining, when one of the first and second washing tubs is in a
dehydration process, whether the other washing tub having no
dehydration status reaches a dehydration process.
[0012] The method may further include: controlling, if the other
washing tub having no dehydration status reaches the dehydration
process, a dehydration operation of the other washing tub in such a
manner that a dehydration rotation is performed in an opposite
direction to another dehydration rotation of the one washing tub in
which the dehydration process was performed earlier than that of
the other washing tub.
[0013] The method may further include: controlling, if the other
washing tub having no dehydration status reaches the dehydration
process, a dehydration operation of the other washing tub to
prevent the other washing tub from entering the dehydration process
until the one washing tub performing the dehydration operation
stops the dehydration operation.
[0014] The determining whether the dehydration process is performed
in the first and second washing tubs may include: determining
whether the first and second washing tubs simultaneously reach the
dehydration process.
[0015] The method may further include: setting, if the first and
second washing tubs simultaneously reach the dehydration process,
different dehydration rotation directions to the first and second
washing tubs, so that dehydration operations of the first and
second washing tubs are performed in different directions.
[0016] The method may further include: adjusting, if the first and
second washing tubs simultaneously reach the dehydration process, a
dehydration operation of the washing tub in such a manner that the
dehydration operation is performed only in one of the first and
second washing tubs.
[0017] The method may further include: adjusting a dehydration
operation of a washing tub having no dehydration status in such a
manner that the washing tub performs the dehydration operation when
the dehydration operation of the other washing tub is
completed.
[0018] The determining whether the dehydration process is performed
in the first and second washing tubs may include: determining
whether the first and second washing tubs simultaneously perform
the dehydration process.
[0019] The method may further include: checking an unbalanced
position of each of the first and second washing tubs when the
first and second washing tubs simultaneously perform the
dehydration process.
[0020] A first drum may be rotatably installed in the first washing
tub, and a second drum may be rotatably installed in the second
washing tub. The unbalanced position may be checked by detecting a
rotation speed of the first or second drum.
[0021] The checking of the unbalanced position by detecting the
rotation speed of the first or second drum may include: checking a
position at which rotational acceleration of the first or second
drum becomes zero.
[0022] The checking of the unbalanced position by detecting the
rotation speed of the first or second drum may include: determining
that the unbalanced position exists in the highest point of the
first or second drum at a time point at which the rotational
acceleration becomes zero in response to the increasing and
decreasing of the rotation speed of the first or second drum.
[0023] The checking of the unbalanced position by detecting the
rotation speed of the first or second drum may include: determining
that the unbalanced position exists in the lowest point of the
first or second drum at a time point at which the rotation
acceleration becomes zero in response to the increasing and
decreasing of the rotation speed of the first or second drum.
[0024] The method may further include: adjusting, if the unbalanced
position of the first or second washing tub is checked, an
unbalanced position of the first or second washing tub, and
reducing vibration of the washing machine.
[0025] The adjusting of the unbalanced position of the first or
second washing tub may include: controlling a difference between a
first position angle of an unbalance of the first washing tub and a
second position angle of an unbalance of the second washing tub to
be equal to or larger than a reference angle, thus adjusting the
unbalanced position.
[0026] The adjusting of the unbalanced position of the first or
second washing tub may include: adjusting the unbalanced position
by adjusting a dehydration rotation speed of the first or second
washing tub.
[0027] The method may further include: setting, if the dehydration
process is simultaneously performed in the first and second washing
tubs, different dehydration rotation directions to the first and
second washing tubs, and adjusting dehydration operations of each
of the washing tubs.
[0028] The method may further include: checking a dehydration
rotation speed of the first and second washing tub; and changing a
rotation direction of one washing tub having a relatively slow
dehydration rotation speed from among the first and second washing
tubs to another rotation direction, and adjusting the dehydration
operation of the washing tub.
[0029] In accordance with another aspect of the present invention,
a washing machine includes: a plurality of washing tubs; and a
controller which checks whether a dehydration operation is
performed in each of the washing tubs, adjusts the dehydration
operation of each of the washing tubs when the dehydration
operation is performed in each of the washing tubs, and reduces
vibration of the washing machine.
[0030] The plurality of washing tubs may include a first washing
tub in which a first drum is rotatably installed and a second
washing tub in which a second drum is rotatably installed. The
controller may reduce vibration of the washing machine by adjusting
rotation operations of the first and second drums.
[0031] The washing machine may further include a speed detector to
detect a speed of the first or second drum.
[0032] The controller may check an unbalanced position of the first
or second washing tub according to a speed of the first or second
drum.
[0033] The controller may reduce vibration of the washing machine
by adjusting an unbalanced position of the first or second washing
tub.
[0034] The controller may adjust a difference in an unbalanced
position between the first washing tub and the second washing tub
to be equal to or larger than a reference angle.
[0035] The controller may reduce vibration of the washing machine
by controlling the first and second drums to have different
dehydration rotation directions opposite to each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] These and/or other aspects of the invention will become
apparent and more readily appreciated from the following
description of the embodiments, taken in conjunction with the
accompanying drawings of which:
[0037] FIG. 1 is a perspective view illustrating the appearance of
a washing machine according to an exemplary embodiment of the
present invention.
[0038] FIG. 2 is a cross-sectional view illustrating a
configuration of a washing machine according to the exemplary
embodiment of the present invention.
[0039] FIG. 3 is a control block diagram illustrating a washing
machine according to an exemplary embodiment of the present
invention.
[0040] FIGS. 4A and 4B illustrate unbalanced positions caused by
laundry contained in a washing machine according to an exemplary
embodiment of the present invention.
[0041] FIG. 4C is a graph illustrating a variation of dehydration
speed under an unbalanced status of a washing machine according to
an exemplary embodiment of the present invention.
[0042] FIGS. 5A and 5B are conceptual diagrams illustrating
positions of unbalance occurring in a dehydration rotation
operation of a washing machine according to an exemplary embodiment
of the present invention.
[0043] FIG. 6A is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to an exemplary embodiment of the present invention.
[0044] FIG. 6B is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0045] FIG. 6C is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0046] FIG. 6D is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0047] FIG. 7 is a flow chart illustrating a method for controlling
an unbalanced position of a washing machine according to an
exemplary embodiment of the present invention.
DETAILED DESCRIPTION
[0048] Reference will now be made in detail to the embodiments,
examples of which are illustrated in the accompanying drawings,
wherein like reference numerals refer to the like elements
throughout. The embodiments are described below to explain the
present invention by referring to the figures.
[0049] FIG. 1 is a perspective view illustrating the appearance of
a washing machine according to an exemplary embodiment of the
present invention.
[0050] Referring to FIG. 1, the washing machine 100 includes a main
body 301 forming an external appearance, an input unit 203, a
display unit 204 display a washing course and an operation status
of the washing machine 100, a first door 201 provided at the front
upper part of the main body 301 to enter a small amount of laundry
in a washing tub, and a second door 202 provided at the front lower
end of the main body 301 to enter a large amount of laundry in a
washing tub. The input unit 203 is provided at the center of the
main body 301, includes a course and function button to select a
washing course of each washing tub and a washing function, and
enters user commands associated with washing courses and operations
of the washing machine 100.
[0051] FIG. 2 is a cross-sectional view illustrating a
configuration of a washing machine according to an exemplary
embodiment of the present invention.
[0052] Referring to FIG. 2, the washing machine 100 includes a
plurality of washing tubs 302 and 303 to classify clothing
according to the amount and type of the clothing and wash the
classified clothing, and includes a first washing tub 302 to wash a
small amount of laundry at an upper end and a second washing tub
303 to wash a large amount of laundry. In this case, the
installation positions of the first and second washing tubs 302 and
303 may be changed to other positions. If necessary, the first and
second washing tubs 302 and 303 may be composed of the washing tubs
having the same capacity. The washing tubs may be classified into a
large-capacity washing tub and a small-capacity washing tub
according to characteristics of the washing machine 100 having
several washing tubs. As described above, if a user desires to wash
a small amount of laundry, the first washing tub 302 having the
small capacity is driven only to prevent unnecessary power
consumption. Meanwhile, a basic configuration of the first washing
tub 302 is equal to that of the second washing tub 303. A first
cylindrical drum 304 having a plurality of holes is provided in the
first washing tub 302 and a second cylindrical drum 305 having a
plurality of holes is provided in the second washing tub 303.
[0053] Two water-supply valves 306a and 306b and a water-supply
hose 307 are provided at one side of the main body 301 of the
washing machine. The water-supply hose 307 is divided into two
parts, one of the two parts is connected to the first washing tub
302 through the water-supply valve 306a, and the other part is
connected to the second washing tub 303 through the water-supply
valve 306b, such that the first water-supply valve 306a or the
second water-supply valve 306b may be selectively opened by a user
command from the input unit 203, or the first and second
water-supply valves 306a and 306b may be automatically opened to
provide the first and second washing tubs 302 and 303 with
water.
[0054] The first motor 310a used as a driver rotating a first
rotation shaft connected to the first drum 304 to perform washing,
rinsing, and dehydration processes is installed at the exterior of
the rear part of the first washing tub 302, and the second motor
310b used as a driver for rotating a second rotation shaft
connected to the second drum 305 is installed at the exterior of
the rear part of the second washing tub 303.
[0055] The first motor 310a is connected to a rotation wheel 311a,
connected to the first drum 304 by a shaft, through a belt.
Likewise, the second motor 310b is connected to a rotation wheel
311b, connected to the second drum 305 by a shaft, through a
belt.
[0056] Meanwhile, a drainage pipe 308a draining dirty water is
provided at one side of the first washing tub 302 and a drainage
pipe 308b is provided at one side of the second washing tub 303.
The first and second drainage pipes 308a and 308b connected to each
other at a lower part of the washing machine 100 have one outlet
309.
[0057] Although the washing machine 100 has exemplarily divided the
first washing tub 302 and the second washing tub 303 in a vertical
direction, the scope of an exemplary embodiment of the present
invention is not limited thereto. The same purpose and effects of
the embodiment of the present invention can be achieved even when
the first and second washing tubs are installed in a horizontal
direction.
[0058] FIG. 3 is a control block diagram illustrating a washing
machine according to an exemplary embodiment.
[0059] Referring to FIG. 3, the washing machine 100 includes an
input unit 203 entering a user's operation command including a
dehydration process setup command, a controller 400 controlling
overall operations (e.g., washing, rinsing, and dehydration
processes) of the washing machine 100, a motor driver 410 driving a
first motor 310a and a second motor 310b according to a control
signal of the controller 400, and a speed detector 420 transmitting
rotation speed signals of the motors 310a and 310b corresponding to
rotation speeds of the drums 304 and 305 inside of the washing tubs
302 and 303 to the controller 400.
[0060] The input unit 203 may allow a user to select a washing
course and a washing function for individual washing tubs 302 and
303, and may allow each washing tub 302 or 303 to enter a
dehydration process according to a user's command.
[0061] The controller 400 adjusts an unbalanced position to reduce
vibration generated by a dehydration operation of the washing
machine 100. In more detail, the controller 400 determines whether
a dehydration process is performed in the first washing tub 302 and
the second washing tub 303. In still more detail, if a dehydration
process is simultaneously performed in both of the washing tubs 302
and 303, the controller 400 detects an unbalanced position of each
of the washing tubs 302 and 303, adjusts a dehydration rotation
speed in the first or second washing tub 302 or 303, and thus
controls a difference in unbalanced phase between the first tub 302
and the second tub 303 to be equal to or higher than a reference
angle.
[0062] When the dehydration process is operating in only one of the
first washing tub 302 and the second washing tub 303 of the washing
machine 100, the controller 400 prevents the other washing tub from
entering the dehydration process, resulting in reduced
vibration.
[0063] When the dehydration process is operating in only one of the
first washing tub 302 and the second washing tub 303 of the washing
machine 100, and the other washing tub 302 or 303 enters the
dehydration process, a dehydration rotation direction of the first
or second washing tub 302 or 303 is changed to an opposite
dehydration rotation direction, and the dehydration process having
the opposite dehydration rotation direction is performed in the
first or second washing tub 302 or 303, thereby reducing vibration
of the washing machine 100. Meanwhile, if the dehydration rotation
directions of two washing tubs 302 and 303 are opposite to each
other, unbalanced rotation directions of the washing tubs 302 and
303 are also opposite to each other, so that vibration of the
washing machine 100 may be reduced as compared to the case in which
the washing tubs 302 and 303 have the same dehydration rotation
direction.
[0064] The motor driver 410 outputs a drive signal, such as a PWM
signal, to the first motor 310a and the second motor 310b upon
receiving a control signal from the controller 400, thereby
adjusting speeds of the first and second motors 310a and 310b.
[0065] The speed detector 420 may be implemented by a hall sensor
or an encoder, and transmits a motor speed signal corresponding to
the number of rotations of each of the first motor 310a and the
second motor 310b to the controller 400.
[0066] FIGS. 4A and 4B illustrate unbalanced positions caused by
laundry contained in the washing machine 100. FIG. 4C is a graph
illustrating a variation of dehydration speed under an unbalanced
status of the washing machine 100.
[0067] Referring to FIG. 4A, if the position of an unbalance 500
generated when the drums 304 and 305 of the washing tubs 302 and
303 rotate in a dehydration process moves upward, a rotation speed
of each of the drums 304 and 305 is reduced. Referring to FIG. 4B,
if the unbalanced position 500 moves downward, a rotation speed of
each drum 304 or 305 is accelerated. The speed variation is
generated when gravity is applied to the unbalance, and the speed
variation of the drum 304 or 305 is denoted by a graph shown in
FIG. 4C. In this case, a difference (p) between a maximum value and
a minimum value in the graph is a variable according to the weight
of unbalance 500 caused by laundry, and this difference (p) may
have a tendency to be proportional to the unbalance 500.
[0068] Herein, considering the gravity effect caused by mass of the
unbalance 500, it can be recognized that the position of the
unbalance 500 may be located at the lowest point A of each drum 304
or 305 at a specific time when the drum 304 or 305 reaches the
highest speed. In contrast, it can be recognized that the position
of the unbalance 500 may be located at the highest point B of each
drum 304 or 305 at a specific time when the drum 304 or 305 reaches
the lowest speed.
[0069] Meanwhile, when the unbalance 500 arrives at the lowest
point A and the highest point B of the drum 304 or 305, the
rotation acceleration of the drum 304 or 305 becomes zero (i.e., a
slope of 0 on a time-speed graph). In more detail, when the
rotation acceleration becomes zero while the rotation speed of the
first or second drum 304 or 305 increases and then decreases, the
unbalance 500 is located at the highest point of the first or
second drum 304 or 305. In contrast, when the rotation acceleration
becomes zero while the rotation speed of the first or second drum
304 or 305 decreases and then increases, the unbalance 500 is
located at the lowest point of the first or second drum 304 or
305.
[0070] FIGS. 5A and 5B are conceptual diagrams illustrating
positions of unbalance occurring in a dehydration rotation
operation of a washing machine 100 having a plurality of washing
tubs according to an exemplary embodiment.
[0071] Referring to FIG. 5A, when the unbalance 510 of the first
washing tub 302 is located at the right side, if the unbalance 520
of the second washing tub 303 is also located at the right side, a
centrifugal force caused by a dehydration rotation of the first and
second washing tubs 302 and 303 is equal to the resultant force
(F=F'+F''), resulting in the occurrence of large variation. In
other words, if positions of the unbalances 510 and 520 of two
washing tubs 302 and 303 have the same phase, two forces F and F''
generating vibration by the dehydration rotation are summed up
(F=F'+F''), so that total vibration of the washing machine 100
increases.
[0072] Referring to FIG. 5B, when the unbalance 510 of the first
washing tub 302 is located at the left side, if the unbalance 520
of the second washing tub 303 is located at the opposite phase of
the unbalance 510 of the first washing tub 302, a centrifugal force
caused by rotation of each washing tub 302 or 303 is compensated
(F=F''-F'), resulting in reduction of vibration.
[0073] In this case, according to one aspect of the present
invention, the controller 400 controls the unbalanced positions of
the first and second washing tubs 302 and 303 to have opposite
phases (180 degrees) therebetween, and therefore the washing
machine 100's vibration caused by the dehydration rotation can be
reduced.
[0074] FIG. 6A is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to an exemplary embodiment of the present invention.
[0075] Referring to FIG. 6A, if a control operation for reducing
vibration of the washing machine 100 begins, the controller 400
determines whether a dehydration process is operating in the first
washing tub 302 and the second washing tub 303 at operation
S10.
[0076] The controller 400 determines whether the dehydration
process is simultaneously operating in two washing tubs 302 and
303. If the dehydration process is simultaneously operating in the
washing tubs 302 and 303 at operation S11, dehydration rotation
directions of the first and second washing tubs 302 and 303 are
opposite to each other at operation S13. In other words, if the
first and second washing tubs 302 and 303 have the same dehydration
rotation directions, any one of the dehydration rotation directions
of the first and second washing tubs 302 and 303 is changed to an
opposite dehydration rotation direction, and then a dehydration
process is performed in the opposite dehydration rotation
direction. If the dehydration rotation directions of the first and
second washing tubs 302 and 303 are opposite to each other, a
conventional rotation direction is maintained, such that a
dehydration process is performed in the conventional dehydration
rotation direction. In this case, a dehydration rotation direction
of one washing tub 302 or 303, having a relatively low dehydration
rotation speed, between the first washing tub 302 and the second
washing tub 303 can be changed at operations S11 and S13.
[0077] Next, the controller 400 performs an unbalanced position
control at operation S16. In this unbalanced position control, the
controller 400 confirms unbalanced positions of the first and
second washing tubs 302 and 303, and reduces vibration of each
washing tub by adjusting the confirmed unbalanced positions. A
detailed description thereof will be described with reference to
FIG. 7.
[0078] In the meantime, when a dehydration process is operating in
only one (i.e., hereinafter referred to as a first washing tub) of
the washing tubs 302 and 303 at operation S12, the controller 400
determines whether the other washing tub (i.e., hereinafter
referred to as a second washing tub) performing no dehydration
process reaches a dehydration process at operation S14.
[0079] If the second washing tub 302 or 303 performing no
dehydration process reaches the dehydration process, the controller
400 performs a dehydration rotation operation in another
dehydration rotation direction different from that of the first
washing tub 302 or 303 which performs the dehydration operation
earlier than the second washing tub 302 or 303, at operation
S15.
[0080] In this case, the second washing tub 302 or 303 performs a
dehydration process in a dehydration rotation direction opposite to
that of the first washing tub 302 or 303 which performs the
dehydration process earlier than the second washing tub 302 or 303,
resulting in reduction of vibration of the washing machine 100.
[0081] FIG. 6B is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0082] The method of FIG. 6B is different from that of FIG. 6A,
because the method of FIG. 6B, when a dehydration process is
operating in only one of the first and second washing tubs 302 and
303 of the washing machine 100, prevents the other washing tub 302
or 303 performing no dehydration process from entering the
dehydration process.
[0083] Referring to FIG. 6B, if the vibration reduction control
operation of the washing machine 100 begins, the controller 400
determines whether the dehydration process is operating in the
first and second washing tubs 302 and 303 at operation S20.
[0084] Next, the controller 400 determines whether the dehydration
process is simultaneously operating in two washing tubs 302 and 303
at operation S21. If the dehydration process is simultaneously
operating in two washing tubs 302 and 303, dehydration rotation
directions of the first and second washing tubs 302 and 303 are
opposite to each other at operation S23.
[0085] Next, the controller 400 confirms unbalanced positions of
the first and second washing tubs 302 and 303. The controller 400
performs an unbalanced position control operation that reduces
vibration of the washing machine by adjusting the confirmed
unbalanced positions at operation S26.
[0086] Meanwhile, when a dehydration process is operating in one
washing tub 302 or 303 at operation S22, the controller 400
determines whether the other washing tub 302 or 303 performing no
dehydration process enters a dehydration process at operation
S24.
[0087] If it is determined that the washing tub 302 or 303
performing no dehydration process reaches the dehydration process,
the controller 400 prevents the washing tub 302 or 303 reaching the
dehydration process from entering the dehydration process at
operation S25.
[0088] The controller 400 determines whether the washing tub 302 or
303 performing the dehydration operation finishes the dehydration
operation at operation S27. If it is determined that the
dehydration process is completed at operation S27, the controller
400 performs a dehydration operation of the washing tub 302 or 303
reaching the dehydration process at operation S28.
[0089] FIG. 6C is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0090] The method of FIG. 6C is different from that of FIG. 6A,
because the method of FIG. 6C does not control dehydration rotation
directions of the first and second washing tubs 302 and 303 to be
opposite to each other, when a dehydration process is
simultaneously operating in two washing tubs 302 and 303.
[0091] Referring to FIG. 6C, if the vibration reduction control
operation of the washing machine 100 begins, the controller 400
determines whether a dehydration process is operating in the first
and second washing tubs 302 and 303 at operation S30.
[0092] Next, the controller 400 determines whether the dehydration
process is simultaneously operating in two washing tubs 302 and 303
at operation S31. If the dehydration process is simultaneously
operating in two washing tubs 302 and 303 at operation S31, the
controller 400 confirms unbalanced positions of the first and
second washing tubs 302 and 303, and performs an unbalanced
position control reducing vibration of the washing machine by
adjusting the confirmed unbalanced positions at operation S35.
[0093] Meanwhile, when the dehydration process is operating in only
one washing tub 302 or 303 at operation S32, the controller 400
determines whether another washing tub 302 or 303 performing no
dehydration process enters the dehydration process at operation
S33.
[0094] If the washing tub 302 or 303 performing no dehydration
process enters the dehydration process at operation S33, the
controller 400 performs a dehydration rotation operation in another
dehydration rotation direction different from that of the other
washing tub 302 or 303 which performs the dehydration operation
earlier than the above washing tub, at operation S34.
[0095] Next, the controller 400 performs an unbalanced position
control operation reducing vibration of the washing machine 100 by
adjusting unbalanced positions.
[0096] FIG. 6D is a flow chart illustrating a method of reducing
vibration in a dehydration process of a washing machine according
to another exemplary embodiment of the present invention.
[0097] The method of FIG. 6D is different from that of FIG. 6B,
because the method of FIG. 6D does not control dehydration rotation
directions of the first and second washing tubs 302 and 303 to be
opposite to each other when a dehydration process is simultaneously
operating in two washing tubs 302 and 303.
[0098] Referring to FIG. 6D, if the vibration reduction control
operation of the washing machine 100 begins, the controller 400
determines whether the dehydration process is operating in the
first and second washing tubs 302 and 303 at operation S40.
[0099] Next, the controller 400 determines whether the dehydration
process is simultaneously operating in two washing tubs 302 and 303
at operation S41. If it is determined that the dehydration process
is simultaneously operating in two washing tubs 302 and 303 at
operation S41, the controller 400 confirms unbalanced positions of
the first and second washing tubs 302 and 303, and performs an
unbalanced position control operation to reduce vibration of the
washing machine by adjusting the confirmed unbalanced positions at
operation S45.
[0100] If the dehydration process is operating in only one washing
tub 302 or 303 at operation S42, the controller 400 determines
whether the other washing tub 302 or 303 performing no dehydration
process reaches the dehydration process at operation S43.
[0101] If the washing tub 302 or 303 performing no dehydration
process reaches the dehydration process, the controller 400
prevents the washing tub 302 or 303 reaching the dehydration
process from entering the dehydration process at operation S44.
[0102] The controller 400 determines whether the dehydration
operation is completed in the washing tub 302 or 303 performing the
conventional dehydration operation at operation S46. If it is
determined that the dehydration operation is completed at operation
S46, the controller 400 performs the dehydration operation of the
washing tub 302 or 303 having reached the dehydration process at
operation S47.
[0103] FIG. 7 is a flow chart illustrating a method of controlling
an unbalanced position of a washing machine 100 according to an
exemplary embodiment of the present invention.
[0104] Referring to FIG. 7, when a dehydration process is operating
in the first and second drums 304 and 305 rotatably installed in
the first and second washing tubs 302 and 303, the controller 400
determines whether a rotation speed of each of the first and second
drums 304 and 305 reaches a steady state at operation S51. In this
case, the rotation speeds of the first and second drums 304 and 305
are respectively equal to those of the first motor 310a and the
second motor 310b at operation S50.
[0105] Next, if the rotation speeds of the first and second drums
304 and 305 reach a steady state at operation S51, the controller
400 detects unbalanced positions of the drums 304 and 305 at
operation S52. In more detail, at operations S51 and S52, the
controller 400 receives information about rotation speeds of the
first and second drums 304 and 305 from the speed detector 420,
checks that the speed of each drum 304 or 305 is changed at
intervals of a predetermined time, recognizes a time point, where
the speed of the drum 304 or 305 increases and then decreases, as
the lowest unbalanced position A of the washing tub, and recognizes
another time point, where the speed of the drum 304 or 305
decreases and then increases, as the highest unbalanced position B
of the washing tub.
[0106] The controller 400 controls a dehydration rotation speed
(S52) when the unbalanced position is detected. In other words, the
controller 400 adjusts the speed of any one or both of the first
drum 304 and the second drum 305, to control an unbalanced position
difference angle (i.e., a phase difference) between the first drum
304 and the second drum 305 to reach a reference angle. Herein, the
reference angle may be optionally set by a designer, and may be
ideally set to 180.degree.. For example, when the unbalanced
position of the first washing tub 302 is located at the lowest
point of the first washing tub 302 and the unbalanced position of
the second washing tub 303 is located at the highest point of the
second washing tub 303, an unbalanced position difference angle
between the first washing tub 302 and the second washing tub 303 is
180.degree. at operation S53.
[0107] In the meantime, the unbalance position difference angle
represents a phase difference angle between unbalanced positions of
individual washing tubs 302 and 303. The unbalanced position
control method of FIG. 7 prevents a centrifugal force F caused by a
dehydration rotation of two drums 304 and 305 from increasing in
response to the increasing position difference angle.
[0108] As is apparent from the above description, the washing
machine and a method of controlling the same according to
embodiments of the present invention can reduce vibration of the
washing machine by adjusting unbalanced positions of two washing
tubs in a dehydration process of the washing machine having the two
washing tubs.
[0109] In accordance with another aspect of the present invention,
two dehydration rotation directions are adjusted to be opposite to
each other in a dehydration process of a washing machine having two
washing tubs. In addition, when one of the two washing tubs is in a
dehydration process, the control method prevents the other washing
tub from entering a dehydration process, thus reducing vibration of
the washing machine.
[0110] Although a few embodiments of the present invention have
been shown and described, it would be appreciated by those skilled
in the art that changes may be made in these embodiments without
departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
* * * * *