U.S. patent application number 13/392582 was filed with the patent office on 2012-06-21 for control method of laundry machine.
This patent application is currently assigned to LG ELECTRONICS INC.. Invention is credited to Jae Hyuk Jang, Bon Kwon Koo.
Application Number | 20120151685 13/392582 |
Document ID | / |
Family ID | 43628194 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120151685 |
Kind Code |
A1 |
Jang; Jae Hyuk ; et
al. |
June 21, 2012 |
CONTROL METHOD OF LAUNDRY MACHINE
Abstract
The patent application discloses a control method of a laundry
machine provided with a balancer. The method includes a balancing
step of at least one time for rotating a drum (30) at a constant
speed for a predetermined time by decelerating the drum (30) if the
drum (30) is accelerated at a predetermined RPM or more. The
balancing step is performed after a rotation speed of the drum (30)
passes through a transient region of the laundry machine (100).
Inventors: |
Jang; Jae Hyuk; (Seoul,
KR) ; Koo; Bon Kwon; (Seoul, KR) |
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
43628194 |
Appl. No.: |
13/392582 |
Filed: |
August 27, 2010 |
PCT Filed: |
August 27, 2010 |
PCT NO: |
PCT/KR2010/005817 |
371 Date: |
February 27, 2012 |
Current U.S.
Class: |
8/137 |
Current CPC
Class: |
D06F 37/203 20130101;
D06F 37/245 20130101; D06F 37/225 20130101; D06F 35/007
20130101 |
Class at
Publication: |
8/137 |
International
Class: |
D06L 1/20 20060101
D06L001/20 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 27, 2009 |
KR |
10-2009-0079912 |
Aug 27, 2009 |
KR |
10-2009-0079923 |
Aug 27, 2009 |
KR |
10-2009-0080120 |
Claims
1. A control method of a laundry machine provided with a balancer,
the control method comprising: a balancing step of at least one
time for rotating a drum at a constant speed for a predetermined
time by decelerating the drum if the drum is accelerated at a
predetermined RPM or more, the balancing step performed after a
rotation speed of the drum passes through a transient region of the
laundry machine.
2. The control method as claimed in claim 1, wherein accelerating
step includes a first accelerating step for accelerating the drum
to reach a first target RPM, a balancing step for carrying out
balancing by decelerating the drum, and a second accelerating step
for accelerating the drum to reach a second target RPM.
3. The control method as claimed in claim 2, wherein the first
target RPM is set equally to the second target RPM.
4. The control method as claimed in claim 3, wherein first target
RPM duration of the first accelerating step is shorter than second
target RPM duration of the second accelerating step.
5. The control method as claimed in claim 3, wherein the balancing
step is carried out by decelerating the drum immediately after the
drum reaches the first target RPM at the first accelerating
step.
6. The control method as claimed in claim 3, wherein, after the
first accelerating step is carried out, the first target RPM and
its duration are determined such that a water content becomes 40%
to 60% or less of a weight of laundry loaded into the drum.
7. The control method as claimed in claim 3, wherein the first
target RPM and its duration are determined such that water
discharge at the first accelerating step is greater than that at
the second accelerating step.
8. The control method as claimed in claim 3, wherein the first
target RPM and its duration are determined such that water
discharge at the first accelerating step is substantially equal to
that at the second accelerating step.
9. The control method as claimed in claim 3, wherein maximum noise
at the first accelerating step is greater than that at the second
accelerating step.
10. The control method as claimed in claim 3, wherein average noise
at the second accelerating step is substantially 55 DB or less.
11. The control method as claimed in claim 2, wherein the first
target RPM is different from the second target RPM.
12. The control method as claimed in claim 11, wherein the first
target RPM is lower than the second target RPM.
13. The control method as claimed in claim 12, wherein, after the
first accelerating step is carried out, the first target RPM and
its duration are determined such that a water content becomes 40%
to 60% or less of a weight of laundry loaded into the drum.
14. The control method as claimed in claim 12, wherein the first
target RPM and its duration are determined such that water
discharge at the first accelerating step is greater than that at
the second accelerating step.
15. The control method as claimed in claim 12, wherein the first
target RPM and its duration are determined such that water
discharge at the first accelerating step is substantially equal to
that at the second accelerating step.
16. The control method as claimed in claim 12, wherein maximum
noise at the first accelerating step is greater than that at the
second accelerating step.
17. The control method as claimed in claim 12, wherein average
noise at the second accelerating step is substantially 55 DB or
less.
18. The control method as claimed in claim 2, wherein water
discharge at the first accelerating step is greater than that at
the second accelerating step.
19. The control method as claimed in claim 2, wherein maximum noise
at the first accelerating step is greater than that at the second
accelerating step.
20. The control method as claimed in claim 2, wherein average noise
at the second accelerating step is substantially 55 DB or less.
21. The control method as claimed in claim 1, wherein the balancing
step is carried out to compensate for variation in eccentricity due
to water discharge of laundry at the accelerating step.
22. The control method as claimed in claim 1, wherein the laundry
machine comprises a driving unit comprising a shaft connected to a
drum, a bearing housing to rotatably support the shaft, and a motor
to rotate the shaft, and a suspension assembly is connected to the
driving unit.
23. The control method as claimed in claim 1, wherein the laundry
machine comprises a rear gasket for sealing to prevent washing
water from leaking from a space between a driving unit and a tub,
and enabling the driving unit movable relative to the tub.
24. The control method as claimed in claim 1, wherein a tub is
supported rigidly more than a drum being supported by a suspension
assembly.
Description
TECHNICAL FIELD
[0001] The present invention relates to a control method of a
laundry machine.
BACKGROUND ART
[0002] In general, a laundry machine may include washing, rinsing
and spinning cycles. Here, the spinning cycle includes a rotating
step of rotating a drum provided in such a laundry machine at the
highest RPM. Because of the step, the spinning cycle would generate
noise and vibration quite a lot, which is required to be solved in
the art the prevent invention pertains to.
DISCLOSURE OF INVENTION
Technical Problem
[0003] Accordingly, the present invention is directed to a control
method of a laundry machine.
[0004] An object of the present invention is to provide a control
method of a laundry machine which can solve the above problem.
Solution to Problem
[0005] To solve the problems, an object of the present invention is
to provide a control method of a laundry machine provided with a
balancer includes a balancing step of at least one time for
rotating a drum at a constant speed for a predetermined time by
decelerating the drum if the drum is accelerated at a predetermined
RPM or more, the balancing step performed after a rotation speed of
the drum passes through a transient region of the laundry
machine.
Advantageous Effects of Invention
[0006] According to the control method of the present invention,
noise of the laundry machine can be reduced remarkably when the
spinning cycle is carried out.
BRIEF DESCRIPTION OF DRAWINGS
[0007] The accompanying drawings, which are included to provide
further understanding of the disclosure and are incorporated in and
constitute a part of this application, illustrate embodiments of
the disclosure and together with the description serve to explain
the principle of the disclosure.
[0008] In the drawings:
[0009] FIG. 1 is a schematic view illustrating a laundry machine to
which a control method according to the first embodiment of the
present invention is applied;
[0010] FIG. 2 is an exploded perspective view illustrating a
laundry machine to which a control method according to the second
embodiment of the present invention is applied;
[0011] FIG. 3 is a coupled sectional view of FIG. 2;
[0012] FIG. 4 is a graph illustrating variation in rotation speed
of a drum in a control method of a spinning cycle of a laundry
machine according to the first embodiment of the present
invention;
[0013] FIG. 5 is a graph illustrating variation in rotation speed
of a drum in a control method of a spinning cycle of a laundry
machine according to the second embodiment of the present
invention;
[0014] FIG. 6 is a graph showing a relation of mass vs. a natural
frequency; and
[0015] FIG. 7 is a graph illustrating vibration characteristics of
the laundry machine of FIG. 3.
BEST MODE FOR CARRYING OUT THE INVENTION
[0016] As follows, an exemplary embodiment of the present invention
will be described in reference to the accompanying drawings. First
of all, a laundry machine a control method according to an
embodiment of the present invention can be applied to will be
described and the control method according to an embodiment of the
present invention will be described after that.
[0017] In reference to FIG. 1, a laundry machine 100 includes a
cabinet 10 configured to define an exterior appearance thereof, a
tub 20 mounted in the cabinet 10 to hold wash water therein and a
drum 30 rotatably provided in the tub 20.
[0018] The cabinet 10 defines the exterior appearance of the
laundry machine 100 and configuration elements which will be
described later may be mounted in the cabinet 10. A door 11 is
coupled to a front of the cabinet 10 and a user may open the door
11 to load laundry items including clothes, beddings, cloth items
and the like (hereinafter, `laundry`) into the cabinet 10.
[0019] The tub 20 configured to hold wash water therein may be
provided in the cabinet 10 and the drum configured to receive the
laundry therein may be rotatale within the tub 20. In this case, a
plurality of lifters 31 may be provided in the drum 30 to lift and
drop the laundry during the rotation of the drum 30.
[0020] The tub 20 may be supported by a spring 50 provided above
the tub 20. Here, a motor 40 is mounted to a rear surface of the
tub 20 to rotate the drum 30. That is, the motor 40 is provided in
a rear wall of the tub 20 and it rotates the drum 30. When
vibration is generated in the drum 30 rotated by the motor 40, the
tub 20 provided in the laundry machine according to this embodiment
may be vibrated in communication with the drum 30. When the drum 30
is rotated, the vibration generated in the drum 30 and the tub 20
may be absorbed by a damper 60 provided below the tub 20.
[0021] As shown in FIG. 1, the tub 20 and the drum 30 may be
provided in parallel to a base of the cabinet 10 or tilted downward
although not shown in the drawing. As the user loads the laundry
into the drum 30, it is advantageous that the front portions of the
tub 20 and the drum 30 should be tilted upward.
[0022] To suppress the vibration of the drum in a spinning cycle
that the drum is rotated, specially, at a high speed, a balancer 70
is provided in a front surface and/or rear surface to balance the
drum and the balancer 70 will be described in detail later.
[0023] According to a laundry machine according to an embodiment,
the tub may be fixedly supported to the cabinet or it may be
supplied to the cabinet by a flexible supporting structure such as
a suspension unit which will be described later. Also, the
supporting of the tub may be between the supporting of the
suspension unit and the completely fixed supporting.
[0024] That is, the tub may be flexibly supported by the suspension
unit which will be described later or it may be complete-fixedly
supported to be movable more rigidly. Although not shown in the
drawings, the cabinet may not be provided unlike embodiments which
will be described later. For example, in case of a built-in type
laundry machine, a predetermined space in which the built-in type
laundry machine will be installed may be formed by a wall structure
and the like, instead of the cabinet. In other words, the built-in
type laundry machine may not include a cabinet configured to define
an exterior appearance thereof independently.
[0025] In reference to FIGS. 2 and 3, a tub 12 provided in the
laundry machine is fixedly supported to a cabinet. The tub 12
includes a tub front 100 configured to define a front part of the
tub and a tub rear 120 configured to define a rear part of the tub.
The tub front 100 and the tub rear 120 are assembled to each other
by screws, to form a predetermined space big enough to accommodate
the drum. The tub rear 120 has an opening formed in a rear portion
thereof and an inner circumference of the rear portion composing
the tub rear 120 is connected with an outer circumference of a rear
gasket 250. The tub back 130 has a through-hole formed in a center
thereof to pass a shaft to pass there through. The rear gasket 250
is made of a flexible material not to transmit the vibration of the
tub back 130 to the tub rear 120.
[0026] The tub rear 120 has a rear surface 128 and the rear surface
128, the tub back 130 and the rear gasket 250 may define a rear
wall of the tub. The rear gasket 250 is connectedly sealed with the
tub back 130 and the tub rear 120, such that the wash water held in
the tub may not leak. The tub back 130 is vibrated together with
the drum during the rotation of the drum. At this time, the tub
back 130 is distant from the tub rear 120 enough not to interfere
with the tub rear. Since the rear gasket 250 is made of the
flexible material, the tub back 130 is allowed to relative-move,
without interference of the tub rear 120. The rear gasket 250 may
include a corrugated portion 252 extendible to a predetermined
length to allow the relative-motion of the tub back 130.
[0027] A foreign substance preventing member 200 configured to
prevent foreign substances from drawn between the tub and the drum
may be connected to a front portion of the tub front 100. The
foreign substance preventing member 200 is made of a flexible
material and it is fixed to the tub front 100. Here, the foreign
substance preventing member 200 may be made of the flexible
material identical to the material composing the rear gasket 250.
Hereinafter, the foreign substance preventing member 200 will be
referenced to as `front gasket`.
[0028] The drum 32 includes a drum front 300, a drum center and a
drum back 340. Balancers 310 and 330 may be installed in front and
rear parts of the drum, respectively. The drum back 340 is
connected with a spider 350 and the spider 350 is connected with
the shaft 351. The drum 32 is rotated in the tub 12 by a torque
transmitted via the shaft 351.
[0029] The shaft 351 is directly connected with a motor 170,
passing through the tub back 130. Specifically, a rotor 174
composing the motor 170 is directly connected with the shaft 351. a
bearing housing 400 is secured to a rear portion of the tub back
130 and the bearing housing 400 rotatably supports the shaft,
located between the motor 170 and the tub back 130.
[0030] A stator 172 composing the motor 170 is secured to the
bearing housing 400 and the rotor 174 is located surrounding the
stator 172. As mentioned above, the rotor 174 is directly connected
with the shaft 351. Here, the motor 170 is an outer rotor type
motor and it is directly connected with the shaft 351.
[0031] The bearing housing 400 is supported via a suspension unit
with respect to a cabinet base 600. The suspension unit 180
includes three perpendicular supporters and two oblique supporters
configured to support the bearing housing 400 obliquely with
respect to a forward and rearward direction.
[0032] The suspension unit 180 may includes a first cylinder spring
520, a second cylinder spring 510, a third cylinder spring 500, a
first cylinder damper 540 and a second cylinder damper 530.
[0033] The first cylinder spring 520 is connected between a first
suspension bracket 450 and the cabinet base 600. The second
cylinder spring 510 is connected between a suspension bracket 440
and the cabinet base 600.
[0034] The third cylinder spring 500 is directly connected between
the bearing housing 400 and the cabinet base 600.
[0035] The first cylinder damper 540 is inclinedly installed
between the first suspension bracket 450 and a rear portion of the
cabinet base. The second cylinder damper 530 is inclinedly
installed between the second suspension bracket 440 and a rear
portion of the cabinet base 600.
[0036] The cylinder springs 520, 510 and 500 of the suspension unit
180 may be elastically connected to the cabinet base 600 enough to
allow a forward/rearward and rightward/leftward movement of the
drum, not connected to the cabinet base 600 fixedly. That is, they
are elastically supported by the base 600 to allow the drum to be
rotated to a predetermined angle in forward/rearward and
rightward/leftward directions with respect to the connected
portion.
[0037] The perpendicular ones of the suspension unit may be
configured to suspend the vibration of the drum elastically and the
oblique ones may be configured to dampen the vibration. That is, in
a vibration system including a spring and damping means, the
perpendicular ones are employed as spring and the oblique ones are
employed as damping means.
[0038] The tub front 100 and the tub rear 120 are fixedly secured
to the cabinet 110 and the vibration of the drum 32 is suspendedly
supported by the suspension unit 180. The supporting structure of
the tub 12 and the drum 32 may be called `separated` substantially,
such that the tub 12 may not be vibrated even when the drum 32 is
vibrated.
[0039] The bearing housing 400 and the suspension brackets may be
connected with each other by first and second weights 431 and
430.
[0040] In case the drum 30 and 32 is rotated after the laundry 1 is
loaded in the drum 30 and 32 of the laundry machine according to
the above embodiments, quite severe noise and vibration may be
generated according to the position of the laundry 1. For example,
when the drum 30 and 32 is rotated in a state of the laundry not
distributed in the drum 30 and 32 uniformly (hereinafter,
`unbalanced rotation`), much noise and vibration may be generated.
Especially, if the drum 30 and 32 is rotated at a high speed to
spin the laundry, the noise and vibration may be problematic.
[0041] Because of that, the laundry machine may include balancer
70, 310 and 330 to prevent the noise and vibration generated by the
unbalanced rotation of the drum 30 and 32. The balancer 70, 310 and
330 may be provided in a front or rear portion, or in both of the
portions of the drum 30 and 32.
[0042] The balancer 70, 310 and 330 is mounted to the drum 30 and
32 to reduce the unbalance. Because of that, the balancer 70, 310
and 330 may have a movable gravity center. The balancers are
mounted to the drum 30 and 32 to reduce the unbalance. Because of
that, the balancer may have a movable gravity center. For example,
the balancer may include movable bodies having a predetermined
weight located therein and a passage the movable bodies move along.
If the balancers may be ball balancers, the balancer 70, 310 and
330 may include balls 72, 312 and 332 having a predetermined weight
located therein and a passage the ball moves along. That is, the
balancer 70, 310 and 330 includes balls 72, 312 and 332 having a
predetermined weight located therein and a passage the ball moves
along.
[0043] More specifically, the balls are rotated by the friction
generated during the rotation of the drum 30 and 32 and they are
not kept unmovable in the drum when the drum is rotated. Because of
that, the balls are rotated at a different speed from the rotation
speed of the drum. Here, the laundry which generates the unbalance
may be rotated at the almost same speed as the speed of the drum
because of the friction generated by the close contact with an
inner circumferential surface of the drum and the lifters provided
in the inner circumferential surface. As a result, the rotation
speed of the laundry is different from that of the balls. The
rotation speed of the laundry is higher than that of the balls
during an initial rotation stage in which the drum is rotated at a
relatively low speed, specifically, a rotation angle speed of the
laundry is higher. In addition, a phase difference between the
balls and the laundry, which is a phase difference with respect to
a rotation center of the drum, may changes continuously.
[0044] Hence, when the rotation speed of the drum is getting
higher, the balls may be in close contact with an outer
circumferential surface of the passage by the centrifugal force. At
the same time, the balls are aligned at a predetermined position
having approximately 90.degree. to 180.degree. of the phase
difference with respect to the laundry. If the rotation speed of
the drum is a predetermined value or more, the centrifugal force is
getting larger and the friction generated between the outer
circumferential surface and the balls is a predetermined value or
more and the balls may be rotated at the same speed as the drum. at
this time, the balls are rotated at the same speed as the drum,
with maintaining the position having the 90.degree. to 180.degree.,
preferably, approximately 180.degree. of the phase difference with
respect to the laundry. In this specification of the present
invention, the rotation of the balls at the predetermined positions
as mentioned above may be expressed as `unbalance corresponding
position` or `balancing`.
[0045] As a result, in case load is concentrated on a predetermined
portion of the drum inside by the laundry, the ball located in the
balancer 70, 310 and 330 may move to an unbalance corresponding
position to reduce the unbalance.
[0046] Hereinafter, control methods of the aforementioned laundry
machines will be described. The laundry machine generally includes
a washing cycle, a rinsing cycle, and a spinning cycle. In the
control method according to the present invention, the spinning
cycle will mainly be described with reference to the accompanying
drawings.
[0047] FIG. 4 is a graph illustrating variation in RPM of the drum
based on the passage of time in the control method of the spinning
cycle according to the present invention. In FIG. 4, a horizontal
axis represents time, and a vertical axis represents variation of
the rotation speed of the drum 30, 32, i.e., revolutions per minute
(RPM).
[0048] Referring to FIG. 4, the control method of the spinning
cycle according to the present invention includes a laundry
distributing step S100 and a spinning step S200.
[0049] The laundry distributing step S100 serves to rotate the drum
at a relatively low speed and uniformly distribute the laundry
inside the drum. The spinning step S200 serves to remove water of
the laundry by rotating the drum at a relatively high speed.
However, it is to be understood that the laundry distributing step
and the spinning step are classified based on their main functions
and are not limited to their main functions. For example, even in
the laundry distributing step, water may be removed from the
laundry by rotation of the drum.
[0050] In this control method, the laundry distributing step S100
includes a wet laundry sensing step S110, a laundry disentangling
step S130, and an eccentricity sensing step S150. The spinning step
S200 includes a transient region passing step S210 and an
accelerating step S230. Hereinafter, each step will be described in
detail.
[0051] If the rinsing cycle ends, the laundry inside the drum 30,
32 is wetted by water. The control part initially senses the amount
of laundry inside the drum 30, 32, i.e., the amount of wet laundry
if the spinning cycle starts (5110).
[0052] The reason why that the control part senses the amount of
wet laundry is that weight of laundry containing water is different
from that of dry laundry even though the control part initially
senses the amount of laundry, which is not wet, i.e., the amount of
dry laundry. The sensed amount of wet laundry may be used as a
factor that determines an allowable condition for accelerating the
drum 30, 32 at the transient region passing step S210, which will
be described later, or determines to again carry out the laundry
distributing step by decelerating the drum 30, 32 through an
eccentricity condition at the transient region passing step
S210.
[0053] In this control method, the amount of wet laundry inside the
drum 30, 32 is sensed when the drum 30, 32 is rotated at a constant
speed for a predetermined time and then decelerated after being
accelerated at a first rotation speed RPM 1, for example, 100 RPM
to 110 RPM. When the drum 30, 32 is decelerated, braking power is
used. Specifically, the amount of wet laundry is sensed using a
rotation rate for an acceleration period when driving motors 40 and
170 rotating the drum 30, 32 are accelerated, a rotation rate for a
deceleration period when the driving motors 40 and 170 are
decelerated, a DC power of the applied motor, etc.
[0054] In the mean time, after sensing the amount of wet laundry,
the control part carries out the laundry disentangling step to
distribute the laundry inside the drum 30, 32 (S130).
[0055] The laundry disentangling step is to uniformly distribute
the laundry inside the drum 30, 32, thereby preventing an
eccentricity rate of the drum 30, 32 from being increased by
concentration of the laundry on a specific region inside the drum
30, 32. This is because that noise and vibration may be increased
when RPM of the drum 32 is increased if the eccentricity rate is
increased. The laundry disentangling step is carried out until the
drum 32 is accelerated in one direction with a predetermined
inclination to reach the rotation speed of the eccentricity sensing
step, which will be described later.
[0056] Subsequently, the control part senses eccentricity of the
drum (S150).
[0057] If the laundry inside the drum 30, 32 is not distributed
uniformly but concentrated on a predetermined region, the
eccentricity rate is increased, whereby noise and vibration may be
caused when the RPM of the drum 30, 32 is increased. Accordingly,
the control part determines whether to accelerate the drum by
sensing the eccentricity rate of the drum.
[0058] Eccentricity sensing is carried out using the difference in
acceleration when the drum is rotated. Namely, when the drum is
rotated, the difference in acceleration between the case where the
drum is rotated downwardly along gravity and the case where the
drum is rotated upwardly contrary to gravity occurs depending on an
eccentricity level. The control part measures this difference in
acceleration by using a speed sensor such as a hole sensor provided
in the driving motors 40 and 170, thereby sensing the eccentricity
rate. Accordingly, if the eccentricity rate is sensed, the laundry
inside the drum sticks to an inner wall of the drum without
dropping even though the drum is rotated. In this case, the drum is
rotated in the range of 100 RPM to 110 RPM, approximately.
[0059] When the sensed eccentricity rate of the drum from a
predetermined amount of wet laundry is more than a reference
eccentricity rate, vibration and noise of the drum may be increased
remarkably if the drum is accelerated at high speed. For this
reason, it may be difficult to accelerate the drum. Accordingly,
the control part can store data having a reference eccentricity
rate previously determined to allow acceleration depending on the
amount of wet laundry, in the form of table. As a result, the
control part can determine whether to accelerate the drum by
applying the sensed amount of wet laundry and the sensed
eccentricity rate to the table. In other words, if the eccentricity
rate depending on the sensed amount of wet laundry is more than the
reference eccentricity rate, the eccentricity rate is too great,
whereby the drum cannot be accelerated. Accordingly, the wet
laundry sensing step, the laundry disentangling step, and the
eccentricity sensing step, as described above, are repeated.
[0060] In the mean time, the wet laundry sensing step, the laundry
disentangling step, and the eccentricity sensing step can be
repeated until the sensed eccentricity rate satisfies a value of
the reference eccentricity rate or less. However, if something is
wrong with the laundry machine, or if the laundry inside the drum
is entangled extremely, the sensed eccentricity rate does not
satisfy the value of the reference eccentricity rate or less,
whereby the wet laundry sensing step, the laundry disentangling
step, and the eccentricity sensing step can be repeated
continuously. Accordingly, it is preferable that the control part
stops rotation of the drum and reports to the user that the
spinning cycle has not ended normally if the drum is not
accelerated for a predetermined time, for example, 20 minutes to 30
minutes, after the spinning cycle starts.
[0061] If the eccentricity rate depending on the sensed amount of
wet laundry is the reference eccentricity rate or less, it
satisfies the condition for allowing acceleration. Accordingly, the
transient region passing step S210 is carried out.
[0062] In this case, the transient region can be defined as a
predetermined RPM band that includes one or more resonant
frequencies. In the transient region, resonance occurs depending on
the system of the laundry machine. If the system of the laundry
machine is determined, the transient region has natural vibration
characteristics generated depending on the determined system of the
laundry machine. The transient region is varied depending on the
system of the laundry machine, and, for example, is in the range of
200 rpm to 270 rpm in the laundry machine according to the first
embodiment and in the range of 200 rpm to 350 rpm in the laundry
machine according to the second embodiment.
[0063] FIG. 6 illustrates a graph showing a relation of mass vs. a
natural frequency. It is assumed that, in vibration systems of two
laundry machines, the two laundry machines have mass of m0 and m1
respectively and maximum holding laundry amounts are .DELTA.m,
respectively. Then, the transition regions of the two laundry
machines can be determined taking .DELTA.nf0 and .DELTA.nf1 into
account, respectively. In this instance, amounts of water contained
in the laundry will not be taken into account, for the time
being.
[0064] In the meantime, referring to FIG. 6, the laundry machine
with smaller mass m1 has a range of the transition region greater
than the laundry machine with greater mass m0. That is, the range
of the transition region having variation of the laundry amount
taken into account becomes the greater as the mass of the vibration
system becomes the smaller.
[0065] The ranges of the transition regions will be reviewed on the
related art laundry machine and the laundry machine of the
embodiment.
[0066] The related art laundry machine has a structure in which
vibration is transmitted from the drum to the tub as it is, causing
the tub to vibrate. Therefore, in taking the vibration of the
related art laundry machine into account, the tub is indispensible.
However, in general, the tub has, not only a weight of its own, but
also substantial weights at a front, a rear or a circumferential
surface thereof for balancing. Accordingly, the related art laundry
machine has great mass of the vibration system.
[0067] Opposite to this, in the laundry machine of the embodiment,
since the tub, not only has no weight, but also is separated from
the drum in view of a supporting structure, the tub may not be put
into account in consideration of the vibration of the drum.
Therefore, the laundry machine of the embodiment may have
relatively small mass of the vibration system.
[0068] Then, referring to FIG. 6, the related art laundry machine
has mass m0 and the laundry machine of the embodiment has mass m1,
leading the laundry machine of the embodiment to have a greater
transition region, at the end.
[0069] Moreover, if the amounts of water contained in the laundry
are taken into account simply, .DELTA.m in FIG. 6 will become
greater, making a range difference of the transition regions even
greater. And, since, in the related art laundry machine, the water
drops into the tub from the drum even if the water escapes from the
laundry as the drum rotates, an amount of water mass reduction come
from the spinning is small. Since the laundry machine of the
embodiment has the tub and the drum separated from each other in
view of vibration, the water escaped from the drum influences the
vibration of the drum, instantly. That is, the influence of a mass
change of the water in the laundry is greater in the laundry
machine of the embodiment than the related art laundry machine.
[0070] Under above reason, though the related art laundry machine
has the transition region of about 200.about.270 rpm, A start RPM
of the transient region of the laundry machine according to this
embodiment may be similar to a start RPM of the transient region of
the conventional laundry machine. An end RPM of the transient
region of the laundry machine according to this embodiment may
increase more than a RPM calculated by adding a value of
approximately 30% of the start RPM to the start RPM. For example,
the transient region finishes at an RPM calculated by adding a
value of approximately 80% of the start RPM to the start RPM.
According to this embodiment, the transient region may include a
RPM band of approximately 200 to 350 rpm.
[0071] In the meantime, by reducing intensity of the vibration of
the drum, unbalance may be reduced. For this, even laundry
spreading is performed for spreading the laundry in the drum as far
as possible before the rotation speed of the drum enters into the
transition region.
[0072] In a case, a balancer is used, a method may be put into
account, in which the rotation speed of the drum passes through the
transition region while movable bodies provided in the balancer are
positioned on an opposite side of an unbalance of the laundry. In
this instance, it is preferable that the movable bodies are
positioned at exact opposite of the unbalance in middle of the
transition region.
[0073] However, as described above, the transient region of the
laundry machine according to this embodiment is relatively wide in
comparison to that of the conventional laundry machine. Because of
that, even if the laundry even-spreading step or ball balancing is
implemented in a RPM band lower than the transient region, the
laundry might be in disorder or balancing might be failed with the
drum speed passing the transient region.
[0074] As a result, balancing may be implemented at least one time
in the laundry machine according to this embodiment before and
while the drum speed passing the transient region. Here, the
balancing may be defined as rotation of the drum at a
constant-speed for a predetermined time period. Such the balancing
allows the movable body of the balancer to the opposite positions
of the laundry, only to reduce the unbalance amount. By extension,
the effect of the laundry even-spreading. Eventually, the balancing
is implemented while the drum speed passing the transient region
and the noise and vibration generated by the expansion of the
transient region may be prevented.
[0075] Here, when the balancing is implemented before the drum
speed passing the transient region, the balancing may be
implemented in a different RPM band from the RPM of the
conventional laundry machine. For example, if the transient region
starts at 200 RPM, the balancing is implemented in the RPM band
lower than approximately 150 RPM. Since the conventional laundry
machine has a relatively less wide transient region, it is not so
difficult for the drum speed to pass the transient region even with
the balancing implemented at the RPM lower than approximately 150
RPM. However, the laundry machine according to this embodiment has
the relatively wide expanded transient region as described above.
if the balancing is implemented at the such the low RPM like in the
conventional laundry machine, the positions of the movable bodies
might be in disorder by the balancing implemented with the drum
speed passing the transient region. Because of that, the laundry
machine according to this embodiment may increase the balancing RPM
in comparison to the conventional balancing RPM, when the balancing
is implemented before the drum speed enters the transient region.
That is, if the start RPM of the transient region is determined,
the balancing is implemented in a RPM band higher than a RPM
calculated by subtracting a value of approximately 25% of the start
RPM from the start RPM. For example, the start RPM of the transient
region is approximately 200 RPM, the balancing may be implemented
in a RPM band higher than 150 RPm lower than 200 RPM.
[0076] Moreover, the unbalance amount may be measured during the
balancing. That is, the control method may further include a step
to measure the unbalance amount during the balancing and to compare
the measured unbalance amount with an allowable unbalance amount
allowing the acceleration of the drum speed. If the measured
unbalance amount is less than the allowable unbalance amount, the
drum speed is accelerated after the balancing to be out of the
transient region. In contrast, if the measured unbalance amount is
the allowable unbalance amount or more, the laundry even-spreading
step may be re-implemented. in this case, the allowable unbalance
amount may be different from an allowable unbalance amount allowing
the initial accelerating.
[0077] In other words, when the rotation speed of the drum 30, 32
passes through the transient region, resonance occurs in the
laundry machine, whereby noise and vibration of the laundry machine
may be increased remarkably. Noise and vibration in the laundry
machine may cause the user to feel displeasure. Moreover, such
noise and vibration may disturb acceleration of the drum.
Preferably, when the rotation speed of the drum passes through the
transient region, if the drum 32 is accelerated by appropriately
controlling an acceleration inclination, noise and vibration should
be maintained within a minimum range.
[0078] In the mean time, the eccentricity rate of the drum 30, 32
may be increased either as the drum 30, 32 is accelerated while the
rotation speed of the drum is passing through the transient region,
or by unexpected impact, which is externally caused. If the
eccentricity rate of the drum 30, 32 becomes greater than a
predetermined value, noise is increased remarkably, whereby it is
difficult to accelerate the drum continuously. Accordingly, when
the rotation speed of the drum passes through the transient region,
the control part needs to continuously sense the eccentricity rate
of the drum 30, 32.
[0079] Also, a vibration sensor may be provided in the drum of the
laundry machine, so that the control part may sense vibration of
the drum when the rotation speed of the drum passes through the
transient region. In particular, in the aforementioned laundry
machine where the tub is separated from vibration of the drum,
since the tub is fixed and the drum is only vibrated, it is
necessary to sense vibration of the drum to prevent the drum being
in contact with the tub. If the vibration and/or eccentricity rate
of the drum 30, 32 as sensed at the transient region passing step
becomes greater than the predetermined value, the control part
repeats the wet laundry sensing step, the laundry disentangling
step and the eccentricity sensing step by decelerating the drum 30,
32.
[0080] Subsequently to the transient region passing step, the
control part carries out the accelerating step S230.
[0081] In this embodiment, the accelerating step S230 includes a
first accelerating step S236 for accelerating the drum 30, 32 to
reach a first target RPM, a balancing step S237 for carrying out
balancing by decelerating the drum to reach a predetermined RPM,
and a second accelerating step S238 for accelerating the drum 30,
32 to reach a second target RPM.
[0082] The control part removes water by increasing the rotation
speed of the drum 30, 32 to reach the first target RPM (S236). In
this case, the first target RPM is set equally to the second target
RPM of the second accelerating step but its duration is set to be
shorter than that of the second target RPM.
[0083] In more detail, at the accelerating step, the drum is
accelerated at a relatively high speed to reach a desired RPM,
whereby water is removed from the laundry. If the drum is
accelerated, water is removed from the laundry by a centrifugal
force. Moreover, a water discharge level is varied depending on
kinds of the laundry. In other words, water is easily removed from
soft clothes such as knit, whereas water is not easily removed from
clothes such as jean. Accordingly, as a water discharge level is
varied depending on the laundry, variation in eccentricity occurs.
In particular, since water is almost removed from clothes such as
knit at the first accelerating step, variation in eccentricity
becomes greater than that of the second accelerating step, which
will be described later.
[0084] However, the balls of the balancer are moved more actively
at a lower speed than a higher speed, especially are moved at a
constant speed more actively than at acceleration. Accordingly, as
the drum is accelerated at a relatively high speed at the
accelerating step, if there is any change in eccentricity due to
water discharge, the balls of the balancer fail to actively move to
the eccentricity corresponding position. For this reason, the drum
30, 32 is rotated at a high speed in a state that the balls of the
balancer are not moved to the eccentricity corresponding position,
whereby noise due to eccentricity is increased remarkably. As a
result, since variation in eccentricity due to water discharge is
not compensated appropriately at the first accelerating step, noise
may be increased. Accordingly, it is preferable that the first
target RPM duration at the first accelerating step is shorter than
the second target RPM duration at the second accelerating step.
Moreover, as shown in FIG. 4, at the first accelerating step S236,
the drum is decelerated directly after reaching the first target
RPM, whereby the balancing step S237 can be carried out.
[0085] In this case, the first target RPM and/or its duration are
determined as follows.
[0086] The first target RPM and/or its duration at the first
accelerating step can be set to reach a noise reference level which
is previously set at the second accelerating step subsequently to
the first accelerating step. In other words, the noise reference
level of the laundry machine can be set based on the spinning cycle
where the drum is spun at a maximum speed. In the control method
according to this embodiment, the noise reference level of the
laundry machine is set based on the noise of the second target RPM
at the second accelerating step.
[0087] It is supposed that the amount of washing water
(hereinafter, referred to as `water content`) remaining in the
laundry is more than a predetermined value when the drum is
accelerated to reach the second target RPM at the second
accelerating step. In this case, if the drum is rotated by the
water content, noise may occur in the range that exceeds the noise
reference level which is previously set. Accordingly, at the first
accelerating step, water contained in the laundry should be reduced
to reach a predetermined value or more. In other words, in order to
reduce noise occurring at the second accelerating step to reach a
value of the noise reference level or less, water should be removed
from the laundry at the first accelerating step.
[0088] Finally, at the first accelerating step, a value of the
first target RPM and/or constant speed rotation duration of the
first target RPM can be varied to control the water content (or
water discharge) at the first accelerating step.
[0089] The water content that can reduce the noise occurring at the
second accelerating step to reach the value of the noise reference
level or less can be controlled appropriately depending on capacity
of the drum and the tub in the laundry machine, the amount of
laundry, and the amount of washing water. For example, in this
embodiment, after the first accelerating step is carried out, the
first target RPM and/or its constant speed rotation duration can be
determined such that the water content becomes 40% to 60% or less
of weight of the laundry loaded into the drum. Alternatively, the
first target RPM and/or its constant speed rotation duration can be
determined such that the water discharge level at the first
accelerating step is equal to or greater than that at the second
accelerating step. For example, in this embodiment, the first
target RPM can be set in the range of 1100 RPM to 1300 RPM,
approximately, and can be maintained for 80 seconds to 100 seconds,
approximately. Preferably, the first target RPM can be maintained
in the range of 1200 RPM for 90 seconds. In this way, if the water
content or water discharge level at the first accelerating step is
set, average noise at the second accelerating step can be reduced
to reach a predetermined value or less, for example, 55 DB or less
when the second accelerating step is carried out by balancing.
[0090] Subsequently, the control part carries out the balancing
step S237 by decelerating the drum to reach the second rotation
speed RPM 2. In this case, the second rotation speed is set to be
greater than the transient region of the laundry machine. The lower
the RPM of the drum 30, 32 is, the better balancing is carried out.
However, if the RPM of the drum 30, 32 is lowered than the
transient region for balancing, noise and vibration may be
generated by resonance. Accordingly, the balancing is preferably
carried out at RPM more than the transient region. Accordingly, in
this control method, the second rotation speed can be set in the
range of 350RPM to 400 RPM.
[0091] At the first accelerating step S236, variation in
eccentricity due to water discharge can be compensated by the
balancing step S237. In other words, since the balls are located to
correspond to the varied eccentricity at the balancing step, noise
can be reduced when the drum is accelerated at the second
accelerating step. In particular, since water is almost removed
from the laundry, which is made of a material to easily remove
water therefrom, at the first accelerating step, the laundry, which
is made of a material to be relatively difficult to remove water
therefrom, remain at the second accelerating step. Accordingly,
variation in eccentricity due to water discharge at the second
accelerating step may not be greater than that at the first
accelerating step. Finally, when the drum is accelerated at a
constant rotation speed at the second accelerating step by the
balancer subjected to balancing at the balancing step, noise can be
minimized.
[0092] In the mean time, FIG. 5 is a graph illustrating a control
method of a spinning cycle of a laundry machine according to the
second embodiment of the present invention. In this embodiment, the
first target RPM is different from the second target RPM.
Hereinafter, the control method will be described based on the
difference between the first target RPM and the second target
RPM.
[0093] Referring to FIG. 5, the first target RPM at the first
accelerating step S236 is different from the second target RPM at
the second accelerating step S268. Moreover, the first target RPM
at the first accelerating step S236 may be smaller than the second
target RPM at the second accelerating step S268. In the
aforementioned embodiment of FIG. 4, since the first target RPM is
set equally to the second target RPM, noise due to variation in
eccentricity at the first accelerating step may be increased to
reach a predetermined value or more. Since such a noise during the
spinning cycle may cause the user to feel displeasure, it is
necessary to reduce noise at the first accelerating step. In order
to reduce noise at the first accelerating step, the first target
RPM is set differently from the second target RPM. Preferably, the
first target RPM is set to be lower than the second target RPM. As
the first target RPM is set to be lower than the second target RPM,
noise at the spinning step can be reduced.
[0094] In the mean time, the first target RPM of the first
accelerating step can be set to reach a noise reference level which
is previously set at the second accelerating step subsequently to
the first accelerating step. In other words, the noise reference
level of the laundry machine can be set based on the spinning cycle
where the drum is spun at a maximum speed. In the control method
according to this embodiment, the noise reference level of the
laundry machine is set based on the noise of the second target RPM
at the second accelerating step.
[0095] It is supposed that the water content remaining in the
laundry is more than a predetermined value when the drum is
accelerated to reach the second target RPM at the second
accelerating step. In this case, if the drum is rotated by the
water content, noise may occur in the range that exceeds the noise
reference level which is previously set. Accordingly, at the first
accelerating step, water contained in the laundry should be reduced
to reach a predetermined value or more. In other words, in order to
reduce noise occurring at the second accelerating step to reach a
value of the noise reference level or less, water should be removed
from the laundry at the first accelerating step.
[0096] Finally, at the first accelerating step, a value of the
first target RPM and/or constant speed rotation duration of the
first target RPM can be varied to control the water content (or
water discharge) at the first accelerating step.
[0097] The water content that can reduce the noise occurring at the
second accelerating step to reach the value of the noise reference
level or less can be controlled appropriately depending on capacity
of the drum and the tub in the laundry machine, the amount of
laundry, and the amount of washing water. For example, in this
embodiment, after the first accelerating step is carried out, the
first target RPM and/or its constant speed rotation duration can be
determined such that the water content becomes 40% to 60% or less
of weight of the laundry loaded into the drum. Alternatively, the
first target RPM and/or its constant speed rotation duration can be
determined such that the water discharge level at the first
accelerating step is equal to or greater than that at the second
accelerating step. In this way, if the water content or water
discharge level is set, average noise at the second accelerating
step can be reduced to reach a predetermined value or less, for
example, 55 DB or less when the second accelerating step is carried
out by balancing.
[0098] Subsequently to the balancing step S237, the control part
carries out water discharge by accelerating the drum to reach the
second target RPM (S238). In this case, the second target RPM may
be set previously by the control part, or may be carried out by
input of the user.
[0099] In the mean time, the balancing step S237 at the first and
second accelerating steps can be carried out depending on the value
of the second target RPM. In other words, if the value of the
second target RPM set previously by the control part or set by
input of the user is greater than a predetermined value, the
balancing step is carried out. If the value of the second target
RPM set previously by the control part or set by input of the user
is a predetermined value or less, the balancing step may not be
carried out. The predetermined value is variable, and for example,
is set in the range of 1200 RPM, approximately, in this
embodiment.
[0100] In the mean time, the control method of the laundry machine
according to this embodiment may further include a balancing step
S232 before the first accelerating step S236. The balancing step
serves to move the balls of the balancer to move to the
eccentricity corresponding position before the drum is accelerated
at a relatively high speed at the first accelerating step.
Accordingly, noise that may occur at the first accelerating step
can be reduced in a predetermined range.
[0101] In the mean time, a control method of a laundry machine
according to the related art includes an `intermediate spinning`
step for removing water by accelerating the drum at RPM lower than
the target RPM several times, before the accelerating step. If
water is contained between the drum and the tub, it may cause noise
and vibration when the drum is accelerated, especially it may
disturb rotation of the drum when the drum is rotated at a high
speed at the accelerating step. In this respect, in the control
method of the laundry machine according to the related art, the
intermediate spinning step has been required necessarily.
[0102] However, in the laundry machine according the second
embodiment of the present invention, since it is important to
prevent the tub from being in contact with the drum, the distance
between the tub and the drum becomes greater than that according to
the related art. As a result, in the laundry machine according to
the second embodiment of the present invention, as the distance
between the tub and the drum becomes greater than that according to
the related art, noise due to water contained the tub may be
reduced when the drum is rotated. Moreover, water contained in the
tub does not disturb rotation of the drum. Accordingly, the control
method of the laundry machine according to the second embodiment of
the present invention may omit the intermediate spinning step,
whereby the time required for the spinning cycle can be
reduced.
[0103] First, vibration characteristics of the laundry machine
according to the embodiment of the present invention will now be
described with reference to FIG. 7.
[0104] As the rotation speed of the drum is increased, a region
(hereinafter, referred to as"transient vibration region") where
irregular transient vibration with high amplitude occurs is
generated. The transient vibration region irregularly occurs with
high amplitude before vibration is transited to a steady-state
vibration region (hereinafter, referred to as "steady-state
region"), and has vibration characteristics determined if a
vibration system (laundry machine) is designed. Though the
transient vibration region is different according to the type of
the laundry machine, transient vibration occurs approximately in
the range of 200 rpm to 270 rpm. It is regarded that transient
vibration is caused by resonance. Accordingly, it is necessary to
design the balancer by considering effective balancing at the
transient vibration region.
[0105] In the mean time, as described above, in the laundry machine
according to the embodiment of the present invention, the vibration
source, i.e., the motor and the drum connected with the motor are
connected with the tub 12 through the rear gasket 250. Accordingly,
vibration occurring in the drum is little forwarded to the tub, and
the drum is supported by a damping means and the suspension unit
180 via a bearing housing 400. As a result, the tub 12 can directly
be fixed to a cabinet 110 without any damping means.
[0106] As a result of studies of the inventor of the present
invention, vibration characteristics not observed generally have
been found in the laundry machine according to the present
invention. According to the general laundry machine, vibration
(displacement) becomes steady after passing through the transient
vibration region. However, in the laundry machine according to the
embodiment of the present invention, a region (hereinafter,
referred to as"irregular vibration") where vibration becomes steady
after passing through the transient vibration region and again
becomes great may be generated. For example, if the maximum drum
displacement or more generated in an RPM band lower than the
transient region or the maximum drum displacement or more of steady
state step in a RPM band higher than the transient region is
generated, it is determined that irregular vibration is generated.
Alternatively, if an average drum displacement in the transient
region, +20% to -20% of the average drum displacement in the
transient region or 1/3 or more of the maximum drum displacement in
the natural frequency of the transient region are generated, it may
be determined that the irregular vibration is generated.
[0107] However, as a result of the studies, irregular vibration has
occurred in a RPM band higher than the transient region, for
example has occurred at a region (hereinafter, referred to
as"irregular vibration region") in the range of 350 rpm to 1000
rpm, approximately. Irregular vibration may be generated due to use
of the balancer, the damping system, and the rear gasket.
Accordingly, in this laundry machine, it is necessary to design the
balancer by considering the irregular vibration region as well as
the transient vibration region.
[0108] For example, the balancer is provide with a ball balancer,
it is preferable that the structure of the balancer, i.e., the size
of the ball, the number of balls, a shape of the race, viscosity of
oil, and a filling level of oil are selected by considering the
irregular vibration region as well as the transient vibration
region. When considering the transient vibration region and/or the
irregular vibration region, especially considering the irregular
vibration region, the ball balancer has a greater diameter of 255.8
mm and a smaller diameter of 249.2. A space of the race, in which
the ball is contained, has a sectional area of 411.93 mm.sup.2. The
number of balls is 14 at the front and the rear, respectively, and
the ball has a size of 19.05 mm. Silicon based oil such as Poly
Dimethylsiloxane (PDMS) is used as the oil. Preferably, oil has
viscosity of 300 CS at a room temperature, and has a filling level
of 350 cc.
[0109] In addition to the structure of the balancer, in view of
control, it is preferable that the irregular vibration region as
well as the transient vibration region is considered. For example,
to prevent the irregular vibration, if the irregular vibration
region is determined, the balancing may be implemented at least one
time before, while and after the drum speed passes the irregular
vibration region. Here, if the rotation speed of the drum is
relatively high, the balancing of the balancer may not be
implemented properly and the balancing may be implemented with
decreasing the rotation speed of the drum. however, if the rotation
speed of the drum is decreased to be lower than the transient
region to implement the balancing, it has to pass the transient
region again. In decreasing the rotation speed of the drum to
implement the balancing, the decreased rotation speed may be higher
than the transient region.
[0110] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
INDUSTRIAL APPLICABILITY
[0111] According to the aforementioned control method of the
present invention, noise of the laundry machine can be reduced
remarkably when the spinning cycle is carried out.
* * * * *