U.S. patent application number 12/453565 was filed with the patent office on 2009-12-17 for washing machine.
This patent application is currently assigned to Le Electronics Inc.. Invention is credited to Jae Hyuk Jang, Deok Kyu Kim, Young Suk Kim, Bon Kwon Koo, Bo Sung Seo, Hyun Seok Seo.
Application Number | 20090308110 12/453565 |
Document ID | / |
Family ID | 40872488 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090308110 |
Kind Code |
A1 |
Koo; Bon Kwon ; et
al. |
December 17, 2009 |
Washing machine
Abstract
A washing machine is provided. The washing machine controls a
dehydration rotation speed by detecting a phase difference between
a ball balancer and the laundry. Further, the washing machine
controls a dehydration rotation speed at a dehydration segment
based on a dehydration rotation speed of a driving device. Thereby,
the washing machine minimizes energy using in a dehydration process
by accelerating the dehydration rotation speed at a point at which
a phase difference between the ball balancer and the laundry is a
maximum. Further, by accelerating the dehydration rotation speed at
a point at which the phase difference is a maximum, a vibration of
the washing machine is remarkably reduced.
Inventors: |
Koo; Bon Kwon; (Seoul,
KR) ; Kim; Deok Kyu; (Seoul, KR) ; Jang; Jae
Hyuk; (Seoul, KR) ; Seo; Bo Sung; (Seoul,
KR) ; Seo; Hyun Seok; (Seoul, KR) ; Kim; Young
Suk; (Seoul, KR) |
Correspondence
Address: |
MCKENNA LONG & ALDRIDGE LLP
1900 K STREET, NW
WASHINGTON
DC
20006
US
|
Assignee: |
Le Electronics Inc.
Yeoungdeungpo-Gu
KR
|
Family ID: |
40872488 |
Appl. No.: |
12/453565 |
Filed: |
May 14, 2009 |
Current U.S.
Class: |
68/23.2 |
Current CPC
Class: |
D06F 37/225
20130101 |
Class at
Publication: |
68/23.2 |
International
Class: |
D06F 35/00 20060101
D06F035/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2008 |
KR |
10-2008-0045676 |
Claims
1. A washing machine comprising: a drum to receive laundry to be
washed; a driving device to deliver a rotational driving force to
the drum; a ball balancer coupled to the drum to rotate in the same
direction as the drum to reduce eccentricity of the drum; a phase
difference detection device disposed at the driving device to
detect a phase difference between the ball balancer and the laundry
as the drum rotates; and a controller to control a dehydration
rotation speed of the drum to dehydrate the laundry based on a
phase difference detected in the phase difference detection
device.
2. The washing machine of claim 1, wherein the controller controls
the dehydration rotation speed that includes: a first dehydration
rotation speed in which the driving device maintains a constant
rotational speed to detect the phase difference; and a second
dehydration rotation speed in which the driving device increases
the constant rotational speed to dehydrate the laundry if the phase
difference detected in the first dehydration rotation speed is
within a setting range.
3. The washing machine of claim 2, wherein the setting range is a
period in which the phase difference increases from a first phase
difference, which is a minimum, to a second phase difference, which
is a maximum.
4. The washing machine of claim 2, wherein if the phase difference
is within the setting range, increasing from a minimum phase
difference to a maximum phase difference, the controller gradually
accelerates the driving device from the second dehydration rotation
speed to a third dehydration rotation speed.
5. The washing machine of claim 2, wherein if the phase difference
is within the setting range, increasing from a minimum phase
difference to a maximum phase difference, the controller
accelerates the driving device from the second dehydration rotation
speed to a third dehydration rotation speed at a predetermined
slope.
6. The washing machine of claim 1, wherein if the phase difference
is within a setting range as an average rotation speed is
accelerated at a predetermined slope, the controller increases a
dehydration rotation speed in order to reduce vibrations produced
by the drum.
7. The washing machine of claim 6, wherein the setting range is a
period in which the phase difference increases from a first phase
difference, which is a minimum, to a second phase difference, which
is a maximum.
8. A washing machine comprising: a drum to receive laundry to be
washed; a driving device to deliver a rotational driving force to
the drum; a ball balancer coupled to the drum to rotate in the same
direction as the drum to reduce eccentricity of the drum; a
rotation speed detection device disposed at the driving device to
detect a dehydration rotation speed of the driving device as the
driving device rotates; and a controller to control the dehydration
rotation speed during a dehydration segment of the laundry based on
the dehydration rotation speed.
9. The washing machine of claim 8, wherein the dehydration segment
comprises: a first dehydration segment during which the driving
device constantly maintains the dehydration rotation speed at an
average rotation speed, and the rotation speed detection device
detects a change of the dehydration rotation speed, and determines
if the dehydration rotation speed is within a setting range; and a
second dehydration segment, following the first dehydration segment
once the dehydration rotation speed is determined to be within a
setting range, where the driving device accelerates the dehydration
rotation speed.
10. The washing machine of claim 9, wherein the setting range is a
period in which an instantaneous rotation speed of the dehydration
rotation speed decreases from a first instantaneous rotation speed,
which is a maximum, to a second instantaneous rotation speed, which
is a minimum.
11. The washing machine of claim 8, wherein if an instantaneous
rotation speed of the dehydration rotation speed is within a
setting range increasing from a first instantaneous rotation speed,
which is a maximum, to a second instantaneous rotation speed, which
is a minimum, the controller gradually accelerates the dehydration
rotation speed of the driving device from a first dehydration
rotation speed to a second dehydration rotation speed.
12. The washing machine of claim 8, wherein if an instantaneous
rotation speed of the dehydration rotation speed is within a
setting range increasing from a first instantaneous rotation speed,
which is a maximum, to a second instantaneous rotation speed, which
is a minimum, the controller controls the driving device to
accelerate the dehydration rotation speed from a first dehydration
rotation speed to a second dehydration rotation speed at a
predetermined slope.
13. The washing machine of claim 8, wherein the controller controls
the driving device to accelerate the dehydration rotation speed at
a first predetermined slope, and if the dehydration rotation speed
is less than an average of an instantaneous dehydration rotation
speed, the controller increases the dehydration rotation speed of
the driving device at a second predetermined slope in order to
reduce a vibration of the drum.
14. A washing machine comprising: a drum for washing the laundry; a
driving device for delivering a driving force to the drum; a ball
balancer coupled to the drum to reduce eccentricity of the drum;
and a controller for controlling a rotational position of the ball
balancer such that a center of gravity of the ball bouncer is
opposite the center of gravity of the laundry during a dehydration
cycle.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from Korean Patent
Application No. 10-2008-0045676 filed on May 16, 2008 in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a washing machine, and more
particularly, to a washing machine for controlling a rotation speed
for a dehydration process by detecting a phase difference between
the laundry and a ball balancer, or a dehydration rotation speed of
a driving device.
[0004] 2. Discussion of the Related Art
[0005] A conventional washing machine generally performs a
dehydration process by constantly sustaining and accelerating a
dehydration rotation speed of a drum. If a ball balancer is used,
however, a drum vibrates due to a phase difference between the
laundry and the ball balancer. Further, a significant amount of
noise may occur in a drum due to the vibration, which can be
bothersome to the user. Conventional washing machines cannot detect
this phase difference and thus are unable to control a dehydration
rotation speed according to the phase difference, when performing a
dehydration process. As a result, conventional washing machines
tend to waste energy due to the effects of the eccentricity of the
rotating drum.
SUMMARY OF THE INVENTION
[0006] The present invention has been made in an effort to solve
the above problems, and the present invention provides a washing
machine that can rapidly perform dehydration by controlling a
dehydration rotation speed and reduce noise due to a vibration of a
drum.
[0007] According to an aspect of the present invention, there is
provided a washing machine including: a drum for washing the
laundry; a driving device for delivering a driving force to the
drum; a ball balancer coupled to the drum to reduce eccentricity of
the drum; a phase difference detection device disposed at the
driving device to detect a phase difference between the ball
balancer and the laundry when dehydrating the laundry; and a
controller for controlling a dehydration rotation speed dehydrating
the laundry based on a phase difference detected in the phase
difference detection device.
[0008] According to another aspect of the present invention, there
is provided a washing machine including: a drum for washing the
laundry; a driving device for delivering a driving force to the
drum; a ball balancer coupled to the drum to reduce eccentricity of
the drum; a rotation speed detection device disposed at the driving
device to detect a dehydration rotation speed of the driving device
when dehydrating the laundry; and a controller for controlling the
dehydration rotation speed at a dehydration segment of the laundry
based on the dehydration rotation speed.
[0009] According to another aspect of the present invention, there
is provided a washing machine including: a drum for washing the
laundry; a driving device for delivering a driving force to the
drum; a ball balancer coupled to the drum to reduce eccentricity of
the drum; and a controller for controlling to position the center
of gravity of the ball balancer in an opposite direction of the
center of gravity of the laundry when dehydrating the laundry.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will become more fully understood from
the detailed description given herein below and the accompanying
drawings, which are given by illustration only, and thus are not
limitative of the present invention, and wherein:
[0011] FIG. 1 is a perspective view illustrating a washing machine
according to an exemplary embodiment of the present invention;
[0012] FIG. 2 is a block diagram illustrating an example of control
flow of the washing machine of FIG. 1;
[0013] FIG. 3 is a conceptual diagram illustrating a phase
difference between the laundry and a plurality of balls;
[0014] FIG. 4 is a graph illustrating a relationship between a
phase difference and a dehydration rotation speed of a motor of
FIG. 2;
[0015] FIG. 5 is a graph illustrating a modified example of the
graph of FIG. 4;
[0016] FIG. 6 is a graph illustrating another modified example of
the graph of FIG. 4;
[0017] FIG. 7 is a graph illustrating another modified example of
the graph of FIG. 4;
[0018] FIG. 8 is a block diagram illustrating another example of
control flow of the washing machine of FIG. 1;
[0019] FIG. 9 is a graph illustrating an example of a dehydration
rotation speed of a motor of FIG. 8;
[0020] FIG. 10 is a graph illustrating a modified example of the
graph of FIG. 9; and
[0021] FIG. 11 is a graph illustrating another modified example of
the graph of FIG. 9.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0022] Hereinafter, exemplary embodiments according to the present
invention will be described in detail with reference to the
accompanying drawings.
[0023] FIG. 1 is a perspective view illustrating a washing machine
100 according to an exemplary embodiment of the present invention.
FIG. 2 is a block diagram illustrating an example of control flow
of the washing machine 100 of FIG. 1.
[0024] Referring to FIG. 1, the washing machine 100 includes a
cabinet 110, having a drum 122 disposed within the cabinet 110 for
washing laundry therein, a washing water supply device (not shown)
for injecting washing water to the drum, and a drainage device (not
shown) for discharging the washing water to the outside after a
washing cycle is terminated in the drum 122. A tub (not shown) may
be disposed within the cabinet 110, which surrounds the drum
122.
[0025] A driving device (not shown) may also be included for
delivering the rotary power to the drum 122 wash, rinse and
dehydrate the laundry. The driving device may include all devices
for delivering a driving force to the drum 122, and hereinafter, a
motor 180 is described as an example of the driving device.
Finally, A ball balancer (not shown) may also be included to reduce
eccentricity of the drum 122 caused by the weight distribution of
the laundry inserted into the drum 122.
[0026] Referring to FIGS. 1 and 2, the washing machine 100 includes
the ball balancer (not shown) coupled to the drum 122 to rotate in
the same direction as the drum 122 to reduce eccentricity of the
drum 122. A phase difference detection device 160 may be disposed
at the driving device to detect a phase difference between the ball
balancer and the laundry is rotating during the dehydrating cycle.
A controller 170 may be provided to control a dehydration rotation
speed of the laundry based on the phase difference detected in the
phase difference detection device 160.
[0027] When the dehydration cycle is performed, the motor 180
delivers a driving force to the drum 122 to rotate the drum at a
high RPM. Accordingly, when drum 122 rotates the laundry within the
drum 122 is also rotated by friction force with an inner side
surface of the drum 122. As the drum 122 accelerates and rotates
rapidly, the laundry becomes compressed at the inner side surface
of the drum 122. The weight distribution in the drum 122 may become
eccentric due to the placement of the compressed laundry and
vibrate due to the eccentricity. The drum 122 also generates noise
due to the vibration. Furthermore, the eccentricity disturbs the
rotation of the drum 122, thus disturbing the dehydration process
and causing potential damage to the washing machine.
[0028] The ball balancer may include a fluid and a plurality of
balls and rotates in accordance with a rotation of the drum 122. As
the ball balancer includes the fluid and the plurality of balls,
when the drum 122 rotates, the fluid and the plurality of balls
also rotate. The ball balancer is not limited thereto and can
include various members for rotating according to a rotation of the
drum 122 and reducing eccentricity by the laundry. Hereinafter, a
case where the ball balancer includes a plurality of balls rotating
according to a rotation of the drum 122 is described as an
example.
[0029] As the drum rotates, the plurality of balls partially
separate and rotate in the same direction as the drum 122. When the
motor 180 reaches a constant average rotation speed, the plurality
of balls gather at one side and rotate. While the plurality of
balls rotate the plurality of balls form a phase difference with
the laundry. At this point, a phase difference detection device 160
measures the phase difference between the laundry and the plurality
of balls.
[0030] Once the phase difference is measured, the phase difference
detection device 160 transmits the measured phase difference to the
controller 170. The controller 170 then calculates the positions of
the laundry and the plurality of balls based on the phase
difference. The controller 170 controls a dehydration rotation
speed of the laundry based on the calculated phase difference. A
method in which the controller 170 controls the dehydration
rotation speed will be described in detail hereinafter.
[0031] FIG. 3 is a conceptual diagram illustrating a phase
difference .theta. between the laundry L and a plurality of balls
U. FIG. 4 is a graph illustrating a relationship between a phase
difference .theta. and a dehydration rotation speed of the motor
180 of FIG. 2.
[0032] Referring to FIGS. 3 and 4, when the drum 122 rotates, the
plurality of balls U rotate. The plurality of rotating balls U form
a phase difference .theta. with the laundry L. The phase difference
detection device 160 detects the formed phase difference .theta.
and transmits the phase difference .theta. to the controller 170.
The transmitted phase difference .theta. is processed in the
controller 170 in a graph form shown in FIG. 3.
[0033] In an exemplary embodiment of the invention, during rotation
the controller 170 constantly sustains an average rotation speed of
the motor 180. Once the average rotation speed is constant, the
plurality of balls U rotate in the same direction as the drum 122.
While the plurality of balls U move according to a rotation of the
drum 122, the plurality of balls U form a phase difference .theta.
with the laundry L. As the motor 180 continues to rotate, the
plurality of balls U instantaneously approach the laundry L, and
the phase difference .theta. between the plurality of balls U and
the laundry L is reduced, as illustrated in state (A) of FIG.
3.
[0034] The phase difference .theta. is then reduced and when the
plurality of balls U overlap with the laundry L, the phase
difference .theta. equals 0.degree. as illustrated in state (B) of
FIG. 3. When the phase difference .theta. equals 0.degree., the
laundry L and the plurality of balls U have the same phase. That
is, the center of gravity of the ball balancer corresponds and
overlaps with the center of gravity of the laundry. When the phase
difference .theta. between the laundry L and the plurality of balls
U overlap as in (B), the eccentricity of the drum 122 is aggravated
by the laundry L and the plurality of balls U. When eccentricity is
aggravated, if the drum 122 rotates, a vibration of the drum 122 is
amplified, thus producing noise. In order for the laundry L to
advance to a dehydration process, however, the eccentricity should
be minimized. Accordingly, if the vibration of the drum is
amplified the laundry cannot advance to a dehydration process.
[0035] As the drum 122 continues to rotate, the plurality of balls
U recede from the laundry L after advancing through state (B) of
FIG. 3. That is, the phase difference .theta. between the plurality
of balls U and the laundry L increases in a direction of rotation
of the drum 122, as shown in state (C) of FIG. 3. As the drum 122
continues to rotate, the phase difference .theta. between the
plurality of balls U and the laundry L becomes 180.degree., as
illustrated in state (D) of FIG. 3. That is, the phase difference
.theta. between the plurality of balls U and the laundry L
increases until whereby the plurality of balls U move to an
opposite side of the laundry L and the plurality of balls U and the
laundry L become balanced.
[0036] Further as illustrated in state (D) of FIG. 3, when the
plurality of balls U and the laundry L are balanced, the center of
gravity of the laundry L and the center of gravity of the ball
balancer are disposed in an opposite positions. Thus, the
eccentricity phenomenon in the drum 122 due to the laundry L is
reduced by the plurality of balls U. More specifically, when the
drum 122 rotates, the laundry L is compressed at an inner side
surface of the drum 122 and dehydration is performed. The drum 122
may be inclined eccentrically to one side about a rotation axis
because of the weight distribution of the laundry L causing the
vibration. As the plurality of balls U move to a 180.degree.
position with respect to the laundry L, the plurality of balls acts
to cause the drum 122 to incline to an opposite side. Thus the
plurality of balls counter and substantially cancel out the
eccentricity caused by the laundry L.
[0037] Accordingly, the eccentricity of the drum 122 may be
partially alleviated, and the drum 122 may be in a state similar to
a state where the laundry L does not exist. With the assistance of
the plurality of balls U in this 180.degree. position, the drum 122
may rotates as if the laundry L did not exist.
[0038] In a conventional washing machine, when dehydration of the
laundry is performed, the motor 180 sustains rotational velocity at
a predetermined speed and is then accelerated again. The controller
170 according to an exemplary embodiment of the invention, however,
repeatedly detects the phase difference .theta. while constantly
sustaining an average rotation speed of the motor 180. In this
case, the dehydration rotation speed includes a first dehydration
rotation speed and a second dehydration rotation speed. The first
dehydration rotation speed is maintained during a phase difference
detection period. Once the phase difference is detected within a
setting range, the drum may then be rotated at a second dehydration
rotation speed and accelerated from there in order to dehydrate the
laundry.
[0039] More specifically, as discussed above, the plurality of
balls U rotate according to a rotation of the motor 180 and form a
phase difference .theta. with the laundry L. Due to movement of the
plurality of balls U, the phase difference .theta. continues to
change. The phase difference detection device 160 detects the phase
difference .theta. and transmits the phase difference .theta. to
the controller 170.
[0040] The controller 170 then obtains a graph of FIG. 4 using the
phase difference .theta.. The controller 170 controls the motor 180
to constantly sustain an average rotation speed of the motor 180
during a detection segment of the phase difference .theta.. If the
phase difference .theta. is within a setting range during the
constant rotation segment, the controller 170 controls an increase
of the average rotation speed in order to dehydrate the laundry L
inside the drum 122. In this case, the dehydration rotation speed
of the drum 122 becomes the second dehydration rotation speed and
the dehydration rotation speed of the drum 122 is gradually
increased from the second dehydration rotation speed.
[0041] The setting range is a period in which the phase difference
.theta. increases from a first phase difference in which the phase
difference .theta. is a minimum to a second phase difference in
which the phase difference .theta. is a maximum. That is, in the
first phase difference, the phase difference .theta. equals
0.degree., and in the second phase difference, the phase difference
.theta. equals 180.degree.. Therefore, the motor 180 is accelerated
to a point at which the phase difference .theta. changes from the
first phase difference to the second phase difference.
[0042] As the motor 180 is accelerated to a point between the first
phase difference and the second phase difference, the drum 122 may
rapidly reach the second phase difference. In the second phase
difference, because the phase difference between the laundry L and
the plurality of balls U equals 180.degree., the drum 122 rotates
in a state where eccentricity is reduced. That is, the controller
170 controls the center of gravity of the ball balancer and the
center of gravity of the laundry to be disposed at an opposite
sides. Once the setting range period is complete the dehydration
rotation speed of the drum 122 may be accelerated to properly
dehydrate the laundry L, thus reducing vibration noise
[0043] FIG. 5 is a graph illustrating a modified example of the
graph of FIG. 4. In FIG. 5, elements similar to or corresponding to
those of the previously described exemplary embodiment are denoted
by the same reference numerals and therefore a detailed description
thereof is omitted, and only dissimilar elements will be described
in detail.
[0044] Referring to FIG. 5, if the phase difference is within a
setting range (i.e. increasing from a first phase difference in
which the phase difference is a minimum to a second phase
difference in which the phase difference is a maximum), the
controller 170 gradually accelerates a dehydration rotation speed
of the motor 180 from the second dehydration rotation speed to a
third dehydration rotation speed.
[0045] More specifically, the phase difference detection device 160
measures the phase difference and transmits the phase difference to
the controller 170. The controller 170 determines whether the phase
difference detected in the phase difference detection device 160 is
within the setting range. If the phase difference is within the
setting range, the controller 170 gradually increases the
dehydration rotation speed from the second dehydration rotation
speed. The controller 170 increases and sustains the dehydration
rotation speed for a predetermined time period, and then
accelerates again. The controller 170 can accelerate the
dehydration rotation speed up to the third dehydration rotation
speed by repeatedly performing the above-described process.
[0046] FIG. 6 is a graph illustrating another modified example of
the graph of FIG. 4. In FIG. 6, elements similar to or
corresponding to those of the previously described exemplary
embodiment are denoted by the same reference numerals and therefore
a detailed description thereof is omitted, and only dissimilar
elements will be described in detail.
[0047] Referring to FIG. 6, if the phase difference is within a
setting range (i.e. increasing from a first phase difference in
which the phase difference is a minimum to a second phase
difference in which the phase difference is a maximum), the
controller 170 accelerates a dehydration rotation speed of the
motor 180 at a predetermined slope, i.e. a constant acceleration.
That is, when a phase difference measured by the phase difference
detection device 160 is transmitted to the controller 170, the
controller 170 determines whether the phase difference is within
the setting range. If the phase difference is within the setting
range, the controller 170 accelerates the dehydration rotation
speed at a constant, predetermined slope. Thus, the dehydration
rotation speed is accelerated from the second dehydration rotation
speed to the third dehydration rotation speed. An acceleration
slope can be set at different values.
[0048] If the phase difference is not within the setting range, the
controller 170 continues to maintain the constant average rotation
speed. In this manner, the controller 170 controls the dehydration
rotation speed in order to reduce eccentricity of the drum 122 by
using a phase difference between the laundry and the plurality of
balls. The washing machine 100 is then able to dehydrate the
laundry in a short time by controlling the dehydration rotation
speed.
[0049] FIG. 7 is a graph illustrating another modified example of
the graph of FIG. 4. In FIG. 7, elements similar to or
corresponding to those of the previously described exemplary
embodiment are denoted by the same reference numerals and therefore
a detailed description thereof is omitted, and only dissimilar
elements will be described in detail.
[0050] Referring to FIG. 7, if the phase difference is within a
setting range (i.e. increasing from a first phase difference in
which the phase difference is a minimum to a second phase
difference in which the phase difference is a maximum) while
accelerating the average rotation speed with a predetermined slope,
the controller 170 controls to increase a dehydration rotation
speed of the motor 180 in order to reduce vibration of the drum
122.
[0051] More specifically, the controller 170 gradually increases an
average rotation speed of the motor 180. As the average rotation
speed is increased, the phase difference detection device 160
measures a phase difference between the laundry and the plurality
of balls and transmits the phase difference to the controller 170.
The controller 170 determines whether the phase difference is
within a setting range, and at the same time accelerates the
average rotation speed at a predetermined slope based on the
measured phase difference.
[0052] If the phase difference is within a setting range, the
controller 170 increases a dehydration rotation speed of the motor
180. If the phase difference is not within a setting range, the
phase difference detection device continues to measure the phase
difference while the controller 170 accelerates an average rotation
speed of the motor 180 at a predetermined slope. In this manner,
the washing machine 100 reduces a vibration and noise of the drum
122 during a dehydration cycle.
[0053] FIG. 8 is a block diagram illustrating another example of
control flow of the washing machine 100 of FIG. 1. In FIG. 8,
elements similar to or corresponding to those of the previously
described exemplary embodiments are denoted by the same reference
numerals and therefore a detailed description thereof is omitted,
and only dissimilar elements will be described in detail.
[0054] Referring to FIG. 8, the washing machine 100 includes a drum
(not shown) for washing the laundry, a driving device 280 for
delivering a driving force to the drum, a ball balancer (not shown)
coupled to the drum to rotate in the same direction as the drum and
to reduce eccentricity of the drum, a rotation speed detection
device 260 disposed at the driving device 280 to detect a
dehydration rotation speed of the driving device 280 when
dehydrating the laundry, and a controller 270 for controlling the
dehydration rotation speed to dehydrate the laundry based on the
dehydration rotation speed of the driving device 280. Other
elements of the washing machine 100 are formed similarly to those
of FIG. 1. The driving device 280 may be any device capable of
delivering a driving force to the drum 122. For illustration
purposes a motor 280 is described as an example of the driving
device 280.
[0055] During a dehydration cycle, the motor 280 delivers a
rotational driving force to rotate the drum 122. Accordingly, the
laundry in the drum 122 also rotate by friction force with an inner
side surface of the drum 122. As the drum 122 rapidly rotates, the
laundry is compressed at the inner side surface of the drum 122.
The drum 122 becomes eccentrically loaded by the weight of the
compressed laundry, thus causing the drum 122 to vibrate. The drum
122 also generates noise due to the vibration. Furthermore, the
eccentricity disturbs the rotation of the drum 122, thus disturbing
the dehydration process and causing potential damage to the washing
machine.
[0056] The ball balancer rotates according to a rotation of the
drum 122. The ball balancer may include a fluid and a plurality of
balls rotating in the same direction as the drum 122, thus, when
the drum 122 rotates, the fluid and the plurality of balls also
rotate. The ball balancer is not limited thereto and may include
various members for rotating according to a rotation of the drum
122 and reducing eccentricity caused by the laundry. For
illustrative purposes, a ball balancer including a plurality of
balls rotating according to a rotation of the drum 122 is described
hereinafter.
[0057] The plurality of balls each rotate in accordance with a
rotation of the drum 122 and partially separate as they rotate.
When an average rotation speed of the motor 280 is constant, the
plurality of balls are gather to one side as they rotate. The
weight of the plurality of balls then form a phase difference with
the weight of the laundry while rotating, and the dehydration
rotation speed changes based on the phase difference.
[0058] The rotation speed detection device 260 measures a
dehydration rotation speed of the motor 280 when the plurality of
balls are gathered to one side. When the rotation speed detection
device 260 measures the dehydration rotation speed and then
transmits the measured dehydration rotation speed to the controller
170. When the dehydration rotation speed is transmitted, the
controller 170 calculates positions of the laundry and the
plurality of balls based on the dehydration rotation speed. The
controller 170 controls the dehydration rotation speed of the
laundry based on the calculated dehydration rotation speed. A
method in which the controller 170 controls the dehydration
rotation speed will be described hereinafter in detail.
[0059] FIG. 9 is a graph illustrating an example of a dehydration
rotation speed of the motor 280 of FIG. 8.
[0060] As illustrated in FIG. 9, when the drum 122 rotates, the
plurality of balls will rotate. The plurality of balls tend to
change the dehydration rotation speed while rotating within the
drum 122. The rotation speed detection device 260 may detect the
dehydration rotation speed. The rotation speed detection device 260
then may transmit the dehydration rotation speed to the controller
270. The transmitted dehydration rotation speed may be processed by
the controller 270 in a graph form as illustrated in FIG. 9.
[0061] The controller 270 constantly sustains an average rotation
speed of the motor 280. The plurality of balls move according to a
rotation of the drum 122 and form a phase difference with the
laundry when an average rotation speed of the motor 280 is
constantly maintained. Once the phase difference is formed, the
dehydration rotation speed continues to change. When the laundry
and the plurality of balls have the same phase, a dehydration
rotation speed of the drum 122 reaches a maximum, eccentricity of
the drum 122 is aggravated by the laundry and the plurality of
balls. When the drum 122 rotates in a state in which eccentricity
is aggravated, a vibration of the drum 122 is amplified and noise
results.
[0062] When the laundry and the plurality of balls are positioned
opposite sides from one another, i.e. 180.degree., the laundry and
the plurality of balls become balanced. Furthermore, the
eccentricity phenomenon due to the weight distribution of the
laundry in the drum is reduced by this positioning of the plurality
of balls.
[0063] More specifically, when the drum 122 rotates to perform a
dehydration cycle, the laundry may be compressed at an inner side
surface of the drum 122. The drum 122 may then be inclined to one
side about a rotation axis due to the weight distribution of the
laundry. As a result the drum 122 may vibrates due to the
eccentricity caused by the laundry. As the plurality of balls move
to a side opposite that of the laundry, the drum 122 may be
inclined to another side by the weight of the plurality of balls.
Thus the plurality of balls counter and substantially cancel out
the eccentricity caused by the laundry. Accordingly, the
eccentricity of the drum 122 is alleviated, and the drum 122 may be
in a state similar to a state where the laundry does not exist. The
drum 122 may then rotate similarly to a case where the laundry does
not exist.
[0064] In a conventional washing machine, during the dehydration
cycle the motor 280 maintains a constant average rotation speed by
accelerating a dehydration rotation speed to a predetermined speed
and then accelerating again. However, the controller 270 of the
washing machine 100 according to an exemplary embodiment of the
present invention detects a dehydration rotation speed of the motor
280 while constantly sustaining an average rotation speed of the
motor 280. More specifically, the plurality of balls rotate
according to a rotation of the motor 280. When the plurality of
balls rotate, the plurality of balls and the laundry form a phase
difference. When the plurality of balls and the laundry form a
phase difference, a dehydration rotation speed of the motor 280
changes. If the phase difference is within a setting range, the
controller 170 controls to increase the average rotation speed in
order to dehydrate the laundry of an internal space of the drum
122.
[0065] The setting range is a period in which an instantaneous
rotation speed of the dehydration rotation speed decreases from a
first instantaneous rotation speed in which an instantaneous
rotation speed of the dehydration rotation speed is a maximum to a
second instantaneous rotation speed in which an instantaneous
rotation speed of the dehydration rotation speed is a minimum.
Therefore, the motor 280 may be accelerated at a point at which the
instantaneous rotation speed changes from the first instantaneous
rotation speed to the second instantaneous rotation speed. If the
motor 280 is accelerated at a point between the first instantaneous
rotation speed and the second instantaneous rotation speed,
eccentricity of the drum 122 is minimized. In the second
instantaneous rotation speed, because the laundry and the plurality
of balls are disposed in an opposite direction, the drum 122
rotates in a state where eccentricity is reduced. Therefore, by
accelerating the dehydration rotation speed of the drum 122,
dehydration of the laundry can be performed. Further, by reducing a
vibration generated when dehydrating the laundry, noise can be
reduced.
[0066] FIG. 10 is a graph illustrating a modified example of the
graph of FIG. 9. In FIG. 10, elements similar to or corresponding
to those of the previously described exemplary embodiment are
denoted by the same reference numerals and therefore a detailed
description thereof is omitted, and only dissimilar elements are
described here in detail.
[0067] Referring to FIG. 10, if an instantaneous rotation speed of
the dehydration rotation speed is within a setting range decreasing
from a first instantaneous rotation speed in which an instantaneous
rotation speed of the dehydration rotation speed is a maximum to a
second instantaneous rotation speed in which an instantaneous
rotation speed of the dehydration rotation speed is a minimum, the
controller 270 repeatedly accelerates the dehydration rotation
speed of the motor 280 and stops the acceleration as it increases
from the first dehydration rotation speed to the second dehydration
rotation speed.
[0068] That is, the rotation speed detection device 260 measures
the dehydration rotation speed and transmits the dehydration
rotation speed to the controller 270. The controller 270 determines
whether the dehydration rotation speed detected in the rotation
speed detection device 260 is within the setting range. If the
dehydration rotation speed is within the setting range, the
controller 270 increases the dehydration rotation speed from the
first dehydration rotation speed. After the controller 270
increases the first dehydration rotation speed it then interrupts
acceleration to maintaining the increased first dehydration speed
for a predetermined period of time. The controller 270 then may
again accelerate and interrupt the dehydration rotation speed. The
controller 270 may continue this pattern to accelerate the first
dehydration rotation speed up to the second dehydration rotation
speed to dehydrate the laundry.
[0069] Further, if a rotation speed of the dehydration rotation
speed is within a setting range decreasing from a first
instantaneous rotation speed in which an instantaneous rotation
speed of the dehydration rotation speed is a maximum to a second
instantaneous rotation speed in which an instantaneous rotation
speed of the dehydration rotation speed is a minimum, the
controller 270 controls acceleration of a dehydration rotation
speed of the motor 280 from the first dehydration rotation speed to
the second dehydration rotation speed at a predetermined slope.
[0070] More specifically, when the measured rotation speed is
transmitted to the controller 270, the controller 270 may determine
whether the dehydration rotation speed is within the setting range.
If the dehydration rotation speed is within the setting range, the
controller 270 then may accelerate the dehydration rotation speed
in which an average rotation speed is accelerated at a
predetermined slope from the first dehydration rotation speed to
the second dehydration rotation speed. If the dehydration rotation
speed is not within the setting range, the controller 270 maintains
the average rotation speed. In this manner the controller 270
controls the dehydration rotation speed in order to reduce
eccentricity of the drum 122 when performing dehydration of the
laundry. Further, the washing machine 100 can dehydrate the laundry
in a short time by controlling the dehydration rotation speed.
[0071] FIG. 11 is a graph illustrating another modified example of
the graph of FIG. 9. In FIG. 11, elements similar to or
corresponding to those of the previously described exemplary
embodiment are denoted by the same reference numerals and therefore
a detailed description thereof is omitted, and only dissimilar
elements are described here in detail.
[0072] Referring to FIG. 11, when the dehydration rotation speed is
accelerated at a predetermined slope, if the dehydration rotation
speed is less than an average rotation speed of the dehydration
rotation speed, the controller 270 controls an increase of the
dehydration rotation speed via the motor 280 in order to reduce
vibrations of the drum 122.
[0073] More specifically, while constantly accelerating a
dehydration rotation speed of the motor 280 at a predetermined
slope the controller 270 may detect a change in the dehydration
rotation speed measured in the rotation speed detection device 260.
The measured dehydration rotation speed is transmitted from the
rotation speed detection device 260 to the controller 270. The
transmitted dehydration rotation speed is compared with an average
rotation speed of the dehydration rotation speed by the controller
270. If the dehydration rotation speed is less than the average
rotation speed, the controller 270 controls to increase the
dehydration rotation speed of the motor 280. Therefore, the washing
machine 100 may reduce vibrations of the drum 122 during the
dehydrating process. As a result of the vibration reduction, noise
is reduced, thereby providing product reliability to consumers.
[0074] A washing machine according to the exemplary embodiments of
the present invention may detect a phase difference between a ball
balancer and the laundry and control a dehydration rotation speed
based on the phase difference. Further, the washing machine may
control a dehydration rotation speed at a dehydration segment based
on a dehydration rotation speed of a driving device. The washing
machine can thus rapidly advance, when to a dehydration process by
controlling a dehydration rotation speed based on the phase
difference or the dehydration rotation speed. Therefore, energy
used by the washing machine may be conserved and used efficiently
using when performing a dehydration process. Furthermore, noise can
be reduced because eccentricity due to a phase difference between
the ball balancer and the laundry can be minimized.
[0075] The embodiments of the invention being thus described, it
will be obvious that the same may be varied in many ways. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be
obvious to one skilled in the art are intended to be included
within the scope of the following claims.
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