U.S. patent application number 12/883800 was filed with the patent office on 2011-04-07 for laundry machine.
Invention is credited to Kyung Seop Hong, Seong Hyeon Kim, Kyu Yeol Koak, Seung Chul PARK.
Application Number | 20110079053 12/883800 |
Document ID | / |
Family ID | 43822135 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110079053 |
Kind Code |
A1 |
PARK; Seung Chul ; et
al. |
April 7, 2011 |
LAUNDRY MACHINE
Abstract
A laundry machine includes a cabinet and a tub is provided in
the cabinet for holding washing water. A drum is rotatably provided
in the tub, and a motor is provided at a rear of a tub for rotating
the drum, where the motor includes a stator provided at a rear wall
of the tub and a rotor. A transfer preventive unit provided at
least at one of the stator and the tub to change a vibration/noise
transfer function between the stator and the tub.
Inventors: |
PARK; Seung Chul; (Seoul,
KR) ; Hong; Kyung Seop; (Seoul, KR) ; Kim;
Seong Hyeon; (Seoul, KR) ; Koak; Kyu Yeol;
(Seoul, KR) |
Family ID: |
43822135 |
Appl. No.: |
12/883800 |
Filed: |
September 16, 2010 |
Current U.S.
Class: |
68/139 |
Current CPC
Class: |
D06F 37/206
20130101 |
Class at
Publication: |
68/139 |
International
Class: |
D06F 25/00 20060101
D06F025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2009 |
KR |
10-2009-0093810 |
Claims
1. A laundry machine comprising: a cabinet; a tub provided in the
cabinet for holding washing water; a drum rotatably provided in the
tub; a motor provided at a rear of a tub for rotating the drum,
wherein the motor comprises a stator provided at a rear wall of the
tub and a rotor; and a transfer preventive unit provided at least
at one of the stator and the tub to change a vibration/noise
transfer function between the stator and the tub.
2. The laundry machine as claimed in claim 1, wherein the
vibration/noise transfer function of the stator is changed by
preventing the vibration of the stator from transmitting to the tub
or changing factors of the transfer function of the stator.
3. The laundry machine as claimed in claim 1, wherein the transfer
preventive unit includes a plurality of tub fastening portions and
a plurality of deformation portions, and wherein each deformation
portion is arranged between tub fastening portions for connecting
the tub fastening portions and deformable for attenuating the
vibration.
4. The laundry machine as claimed in claim 3, wherein the transfer
preventive unit further includes a connection portion extended from
the tub fastening portion in opposite directions and connected to
an adjacent deformation portion.
5. The laundry machine as claimed in claim 4, wherein the
connection portion and the adjacent deformation portion are
arranged in the same plane.
6. The laundry machine as claimed in claim 4, wherein the
connection portion is connected to at least one of the deformation
portion and the tub fastening portion at an angle.
7. The laundry machine as claimed in claim 6, wherein the
connection portion comprises at least one introducing portion
connecting to at least one of the deformation portion and the tub
fastening portion at an angle.
8. The laundry machine as claimed in claim 6, wherein the
connection portion comprises a plurality of introducing portions,
wherein one introducing portion is formed to have an angle with
another introducing portion.
9. The laundry machine as claimed in claim 4, wherein the stator
further includes an insulator, and the transfer prevention unit is
arranged in a plane different from a plane of the insulator.
10. The laundry machine as claimed in claim 9, wherein the
connection portion comprises a plurality of introducing portions,
wherein the plurality of introducing portions form a stair-like
structure such that the connection portion is arranged in a plane
lower than the tub fastening portion.
11. The laundry machine as claimed in claim 9, wherein a tub
fastening portion of the transfer prevention unit is arranged on a
plane different from the plane of the insulator, and a connection
portion and a deformation portion of the transfer prevention unit
extends at planes different from each other.
12. The laundry machine as claimed in claim 2, wherein at least one
of a natural frequency and a critical frequency of the stator is
changed, and the critical frequency is defined as a frequency at
which vibration of the rotor is transferred to a tub through the
stator without being amplified and attenuated.
13. The laundry machine as claimed in claim 12, wherein the
critical frequency is adjusted to be smaller than a maximum
frequency range of the rotor.
14. The laundry machine as claimed in claim 12, wherein the
critical frequency is adjusted to be lower than a maximum vibration
frequency of the rotor.
15. The laundry machine as claimed in claim 14, wherein the
critical frequency is adjusted by reducing the natural frequency of
the stator.
16. The laundry machine as claimed in claim 15, wherein the natural
frequency is reduced by changing an elastic modulus of the
stator.
17. The laundry machine as claimed in claim 16, further comprising
a supporting member on an underside of the stator, and the
supporting member connects the stator to the tub.
18. The laundry machine as claimed in claim 17, wherein at least
one of a thickness and a length of the supporting member is
adjusted such that a critical frequency of the stator is set below
a maximum vibration frequency of the rotor.
19. The laundry machine as claimed in claim 1, wherein the transfer
prevention unit is made of an elastic material.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of the Patent Korean
Application No. 10-2009-0093810, filed on Oct. 1, 2009, which is
hereby incorporated by reference as if fully set forth herein.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] The present disclosure relates to laundry machines, and,
more particularly, to a laundry machine which may reduce vibration
and/or noise.
[0004] 2. Discussion of the Related Art
[0005] The laundry machine, used for treating laundry, performs
washing, rinsing, spinning and/or drying, and so on. In the
meantime, the laundry machine generates vibration and/or noise due
to rotation of a drum provided therein, and particularly, generates
much vibration and/or noise while performing spinning.
SUMMARY
[0006] Accordingly, the present disclosure is directed to a laundry
machine.
[0007] An object of the present disclosure is to provide a laundry
machine which may reduce vibration and/or noise.
[0008] Additional advantages, objects, and features of the
disclosure will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0009] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a laundry machine includes a motor with a
rotor and a stator, wherein at least a vibration/noise transfer
function between the stator and a tub is changed.
[0010] It is to be understood that both the foregoing general
description and the following detailed description of the present
disclosure are exemplary and explanatory and should not be
construed as limiting the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The accompanying drawings, which are included to provide a
further understanding of the disclosure and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the disclosure and together with the description serve to explain
the principle of the disclosure. In the drawings:
[0012] FIG. 1 illustrates a perspective view of an exterior of a
laundry machine;
[0013] FIG. 2 illustrates a side sectional view of rear portions of
a tub and a drum of the laundry machine in FIG. 1;
[0014] FIG. 3 illustrates a graph showing frequency vs. vibration
and/or noise of a rotor in a related art laundry machine;
[0015] FIG. 4 illustrates a graph showing frequency vs. vibration
and/or noise of a stator in a related art laundry machine;
[0016] FIG. 5 illustrates a graph showing frequency vs. vibration
and/or noise of a related art laundry machine;
[0017] FIG. 6 illustrates a graph showing frequency vs. vibration
and/or noise of a rotor in a laundry machine in accordance with a
preferred embodiment of the present invention;
[0018] FIG. 7 illustrates a front view of a stator in accordance
with a preferred embodiment of the present invention;
[0019] FIG. 8 illustrates a front view of a stator in accordance
with another preferred embodiment of the present invention;
[0020] FIG. 9 illustrates a front view of a stator in accordance
with another preferred embodiment of the present invention;
[0021] FIG. 10 illustrates a front view of a stator in accordance
with another preferred embodiment of the present invention;
[0022] FIG. 11 illustrates a graph showing frequency vs. vibration
and/or noise of a stator in a laundry machine in accordance with
another preferred embodiment of the present invention;
[0023] FIG. 12 illustrates a graph showing frequency vs. vibration
and/or noise of a laundry machine in a laundry machine in
accordance with another preferred embodiment of the present
invention; and
[0024] FIG. 13 illustrates a partial side sectional view showing a
structure for changing a factor of a vibration transfer function of
a stator.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0025] Reference will now be made in detail to the specific
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers will be used throughout the drawings to
refer to the same or like parts.
[0026] FIG. 1 illustrates a perspective view of an exterior of a
laundry machine.
[0027] Referring to FIG. 1, the laundry machine 100 includes a
cabinet 10 which forms an exterior of the laundry machine 100, a
tub 20 (see FIG. 2) provided in the cabinet 10 for holding washing
water and a drum 30 rotatably provided in the tub 20 for holding
washing objects.
[0028] The cabinet 10 forms an exterior of the laundry machine 100,
and has various elements of the laundry machine 100 mounted
therein. The cabinet 10 has an opening 14 at a front side and a
door 12 for selectively opening/closing the opening 14. According
to this, the user can open the door 12, and introduce washing
objects into the drum 30 in the cabinet 10 through the opening
14.
[0029] The tub 20 is provided in the cabinet 10 for holding washing
water, and the drum 30 is rotatably provided in the tub 20 for
holding the washing objects. In this configuration, on an inner
surface of the drum 30, there may be a plurality of lifters 32 for
lifting and dropping the washing objects when the drum 30
rotates.
[0030] In the meantime, the tub 20 is suspended by springs (not
shown) on an upper side thereof and dampers (not shown) on a lower
side thereof. The tub 20 also has a motor 40 (See FIG. 2) at a rear
of the tub 20 for rotating the drum 30.
[0031] FIG. 2 illustrates a side sectional view of rear portions of
the tub 20 and the drum 30 of the laundry machine in FIG. 1.
[0032] Referring to FIG. 2, the motor 40 has a rotor 42 and a
stator 44 and is mounted to a rear wall 22 of the tub 20. The rotor
42 is connected to the drum 30 through a rotation shaft 34, and the
stator 44 is mounted to the rear wall 22 of the tub with a gap
between the stator 44 and the rotor 42. Accordingly, when the rotor
42 rotates owing to interaction between the rotor 42 and the stator
44, the drum 30 rotates owing to the rotation of the rotation shaft
34.
[0033] In the meantime, when the drum 30 is rotated by the motor
40, the laundry machine 100 generates vibration and/or noise with
the rotation of the drum 30. Particularly, in the case where the
drum 30 rotates for extracting water from the washing objects and
is running at a comparatively high speed, the vibration and/or
noise of the laundry machine 100 is intense.
[0034] The vibration and/or noise are transmitted from the rotor 42
to the tub 20 through the stator 44. The generation of the
vibration and/or noise at the motor will first be reviewed, and
then, the laundry machine in accordance with different embodiments
of the present invention for preventing the vibration and/or noise
will be described.
[0035] FIGS. 3, 4 and 5 illustrate graphs showing frequency vs.
vibration of the rotor, the stator and the laundry machine of a
related art laundry machine, respectively. For reference, the
graphs of frequency vs. noise of the rotor, the stator and the
laundry machine of the related art laundry machine are similar to
the graphs of frequency vs. vibration of the rotor, the stator and
the laundry machine, and thus the graphs of frequency vs. noise are
not additionally shown.
[0036] Referring to FIG. 3, if the rotor 42 of the motor 40
rotates, the rotor 42 vibrates. Furthermore, following an increase
in rotation RPM of the rotor 42, the vibration is distinctive at
frequencies corresponding to multiples of the rotation RPM. With
reference to FIG. 3, it shows that the vibration of the rotor 42 is
distinctive at frequencies corresponding to multiples of the
rotation RPM.
[0037] Moreover, FIG. 3 shows frequency ranges A and B in which the
vibration of the rotor 42 become heavier distinctively at regular
intervals. The frequency ranges A and B in which the vibration of
the rotor 42 become heavier distinctively are caused by
characteristics of the rotor 42.
[0038] In detail, the frequency ranges A and B ranges in which the
vibration of the rotor 42 become heavier correspond to frequencies
corresponding to multiples of a greatest common divisor of numbers
of slots and poles of the motor 40. For example, the frequency
range A range may correspond to the frequency corresponding to a
multiple of unity of a greatest common divisor of numbers of slots
and poles of the motor 40, and the frequency range B range may
correspond to the frequency corresponding to a multiple of two of
the greatest common divisor of numbers of slots and poles of the
motor 40. In the end, the vibration of the rotor 42 becomes heavier
at frequencies corresponding to a multiple of the rotation RPM, and
particularly, becomes heavier distinctively at maximum vibration
frequencies corresponding to a multiple of a greatest common
divisor of numbers of slots and poles.
[0039] In the meantime, FIG. 4 illustrates a graph showing a
vibration transfer function of the stator 44. In FIG. 4, an
abscissa represents the rotation RPM of the rotor (frequency), and
an ordinate represents a vibration transfer rate. That is, with
reference to FIG. 4, if a vibration transfer function curve is
greater then unity, the stator 44 transmits the vibration from the
rotor 42 to the tub 20 after amplifying the vibration generated at
the rotor 42. If a vibration transfer function curve is smaller
then unity, the stator 44 transmits the vibration from the rotor 42
to the tub 20 after attenuating the vibration generated at the
rotor 42.
[0040] Referring to FIG. 4, the stator 44 has a transfer rate which
becomes greater than unity as the rotation RPM of the rotor 42
increases, and becomes the maximum at a certain frequency.
According to tests of the inventor, the frequency at which the
transfer rate becomes the maximum corresponds to a natural
frequency fn of the stator 44, substantially.
[0041] In the end, if the rotation RPM of the rotor 42 coincides
with the natural frequency fn of the stator 44 substantially, the
transfer rate becomes the maximum to amplify the vibration
generated at the rotor 42 to the maximum, which is transmitted to
the tub 20 through the stator 44. In the meantime, even though
varying with different kinds of laundry machines, the natural
frequency of the stator 44 falls on a RPM range in which the drum
30 rotates in a spinning course of the laundry machine. Therefore,
if the drum 30 is spun for water extraction, the vibration transfer
rate of the stator 44 becomes the maximum if the rotation RPM of
the rotor coincides with the natural frequency of the stator 44
substantially, and the maximum vibration is transmitted to the tub
20.
[0042] Referring to FIG. 4, if the rotation RPM of the rotor 42
passes the natural frequency fn of the stator 44, the transfer rate
is reduced, and if the rotation RPM passes a certain frequency, the
transfer rate becomes smaller than unity. A frequency when the
transfer rate is at unity is called critical frequency fc, at which
the vibration transmitted to the tub 20 through the stator 44 is
without amplification or attenuation. If the rotation RPM passes
the critical frequency fc, the transfer rate becomes smaller than
unity, thereby transmitting the vibration to the tub 20 through the
stator 44, after attenuating the vibration generated at the rotor
42.
[0043] In the meantime, FIG. 5 illustrates a graph showing
frequency vs. vibration of the laundry machine 100 compounded by
the graphs of FIGS. 3 and 4.
[0044] Referring to FIG. 5, the vibration of the laundry machine
100 increases as the rotation RPM of the rotor 42 increases. As
described before, this is because the vibration of the rotor 42
becomes heavier at a multiple of the rotation RPM, and such
vibration is transmitted through the stator 44. Particularly, the
vibration of the laundry machine 100 becomes distinctively heavier
in an .alpha. range.
[0045] In detail, the .alpha. range is a range which includes the
maximum vibration frequency at which the vibration of the rotor 42
becomes the heaviest, and corresponds to a range which includes the
natural frequency fn at which the vibration transfer rate of the
stator 44 is at maximum.
[0046] That is, the heaviest vibration B (See FIG. 3) is generated
at the rotor 42 in the .alpha. range, and the vibration is
amplified to the maximum (at the natural frequency fn) at the
stator 44 and transmitted to the tub 20. Therefore, the vibration
of the laundry machine 100 becomes the heaviest in the .alpha.
range.
[0047] If the rotation RPM of the rotor passes the a range, the
vibration is reduced slowly. This is because of the reduction of
the transfer rate of the transfer function of the stator 44 until
the transfer rate of the transfer function becomes smaller than
unity when the rotation RPM of the rotor passes the critical
frequency fc of the stator 44.
[0048] Accordingly, in order to reduce the vibration of the laundry
machine, vibration characteristics of the rotor 42 may be changed,
or the transfer function of the stator 44 may be changed, which
will be described.
[0049] In order to change vibration characteristics of the rotor
42, a voltage (power) to the motor 40 may be reduced. By doing
this, amplitude of the vibration generated at the rotor 42 may be
reduced.
[0050] FIG. 6 illustrates a graph showing changes in vibration if
vibration characteristic of the rotor 4 is changed. As shown in
FIG. 6, it can be noted that the amplitude of the vibration is
reduced in comparison to the graph of FIG. 3. That is, by reducing
magnitude of the vibration generated at the rotor 42, the vibration
generated at the laundry machine may be reduced.
[0051] On the other hand, by changing the vibration transfer
function of the stator 44, the transmission of the vibration from
the stator 44 to the tub 20 may be reduced or prevented. Changing
the factors of the transfer function, for example, the natural
frequency and/or the critical frequency, will now be described.
[0052] An embodiment will be described, in which the factors of the
transfer function, for example, the natural frequency and/or the
critical frequency, is changed to lower the vibration transfer rate
in order to reduce or prevent the transmission of the vibration
from the stator 44 to the tub 20.
[0053] FIG. 7 illustrates a front view of the stator 44 having a
structure for preventing the vibration from transmitting from the
stator 44 to the tub 20.
[0054] Referring to FIG. 7, the stator 44 has a coil unit 445 for
forming electromagnetic force, and an insulator 450 for mounting
the coil unit 445 thereto. For convenience's sake, the drawing
shows no coil at the coil unit 445, but only teeth 446 on which the
coil is wound thereon.
[0055] In detail, the stator 44 has a stator core (not shown)
having a stack of thin conductive plates, or a long conductive band
wound into a helix, and an insulator 450 attached to an upper
surface and a lower surface of the stator core to enclose the
stator core. The insulator has a plurality of teeth 446 projected
from a circumference thereof. As the coil is wound around the
tooth, the coil unit 445 is formed. Moreover, the rotor 42 is
arranged spaced a distance away from the stator 44, so that the
rotor 42 can rotate owing to interaction between the magnets of the
rotor 42 and the coil of the stator 44.
[0056] In the meantime, if the rotor 42 rotates owing to
interaction between the rotor 42 and the stator 44, vibration takes
place at the stator 44. If the vibration of the stator transmits to
the tub 20 along fastening portion of the stator 44 and the tub 20,
the vibration of the tub 20 increases. Accordingly, in the
embodiment, transfer preventive unit is provided for preventing
transfer of the vibration from the stator 44 to the tub 20.
[0057] According to one embodiment, the transfer preventive unit
includes a plurality of tub fastening portions 193 and a plurality
of deformation portions 191 each arranged between tub fastening
portions 193 for connecting the tub fastening portions 193 and
deformable for attenuating the vibration.
[0058] The transfer preventive unit also includes a connection
portion 192 extended from the tub fastening portion 193 in opposite
directions and connected to an adjacent deformation portion 191.
The connection portion 192 is also bent and extended from the tub
fastening portion 193, and bent from the deformation portion
191.
[0059] The plurality of deformation portions 191 and the plurality
of tub fastening portions 193 are spaced at regular intervals. The
tub fastening portions 193, the connection portions 192 and
deformation portions 191 can be arranged on the same plane.
Therefore, the vibration generated at the stator 44 is attenuated
by the connection portion 192. Since the vibration is attenuated
and thus, is not easy to transmit to the tub 20, the noise caused
by the vibration of the tub 20 may be reduced.
[0060] Other embodiments are possible. For instance, in another
embodiment, the connection portions 192 may be connected to the
deformation portions 191 or the tub fastening portions 193
respectively at an angle. Moreover, the angle can be a right angle,
substantially. The angle is not limited to the right angle, but
includes all of the angles that can attenuate the vibration from
the stator.
[0061] The transfer preventive unit may be formed on a plane
different from a plane of the insulator 450. That is, the transfer
preventive unit may be formed, lower than the insulator 450, or
higher than the insulator 450. According to this, since the
transfer preventive unit is arranged on a plane different from the
insulator 450, the vibration may be effectively attenuated.
Moreover, the tub fastening portion 193 of the transfer preventive
unit may be arranged on a plane different from the plane of the
insulator 450. If the tub fastening portion 193 is arranged on a
plane different from the plane of the insulator 450, the bends of
the connection portions 192 and the deformation portions 191 may be
formed to be extended to planes different from each other.
[0062] Effects of the transfer preventive unit will now be
described.
[0063] When the laundry machine 100 operates, the motor 40 is
driven. While the motor 40 is driven, a current is applied to the
coil portion 445 of the stator 44. The stator 44 generates an
electromagnetic force owing to the current applied and thus, the
electromagnetic force generated at the stator 44 interacts with a
magnet portion of the rotor 42 to rotate the rotor, which in turn,
rotates the rotation shaft 34 of the drum 30. The rotation of the
rotation shaft 34 rotates the drum 30.
[0064] In the meantime, when the motor is driven, vibration takes
place due to a repulsive force of the stator 44. The vibration is
transmitted to the stator 44, making the stator 44 vibrate. The
embodiment provides a transfer preventive unit for preventing the
vibration from transmitting to the tub 20. If the vibration takes
place at the stator 44, deformation takes place at the deformation
portion 191 of the transfer preventive unit, to absorb the
vibration. Accordingly, since the vibration does not transmit from
the stator 44 to the tub fastening portion 193, the vibration is
not transferred from the stator 44 to the tub 20.
[0065] FIG. 8 illustrates an embodiment different from FIG. 7. The
embodiment will be described focused on differences from FIG.
7.
[0066] Referring to FIG. 8, the transfer preventive unit includes a
plurality of tub fastening portions 293 each fastened to the tub 20
for securing the stator 44, a plurality of connection portions 292
each arranged between the tub fastening portions 293 for
attenuating the vibration as the connection portion 292 is bent,
and a plurality of deformation portions 291 extended from the
plurality of connection portions 292, respectively.
[0067] That is, the connection portion 292 formed bent from the
deformation portion 291 extends the deformation portion 291 to the
tub fastening portion 293. In the meantime, the connection portions
292 are respectively connected to the deformation portions at an
angle. The angle may be a right angle, substantially.
[0068] In the meantime, the connection portion 292 may also include
at least one introducing portion 294 or a projection (not shown).
The at least one introducing portion 294 may be provided to the tub
fastening portion 293, or the deformation portion 291. Moreover,
the at least one introducing portion 294 may have a bend. Moreover,
if there is a plurality of the introducing portions 294, one
introducing portion 294 may be formed to have an angle to the other
introducing portion (not shown). In this case, the vibration being
transferred to the connection portions 292 is attenuated as the
vibration passes through the introducing portions 294 step by step.
Accordingly, the vibration can be reduced effectively and quickly,
permitting the reduction of vibration from being transferred to the
tub.
[0069] In the meantime, the tub fastening portion 293 is arranged
on a same plane as the insulator 450. Accordingly, the introducing
portion 294 may be arranged on the same plane with the tub
fastening portion 293. The tub fastening portion 293 can be
arranged on a plane different from a plane of the insulator 450.
For example, at least one introducing portion 294 may be formed in
a stair fashion so as to be arranged on lower planes gradually, and
the connection portions 292 may be arranged on a plane lower than
the tub fastening portions 293. In the embodiment where the
connection portion includes at least one introducing portion 294,
the at least one introducing portion 294 may be arranged on a plane
lower than the tub fastening portions 293. The connection portions
292 may be arranged on a plane lower than the at least one
introducing portion 294. Accordingly, the connection portions 292
may be arranged on a same plane as the tub fastening portions 293.
The above description is applicable to the embodiment where the at
least one introducing portion 294 is formed in the stair fashion so
as to be arranged on higher planes, gradually.
[0070] FIG. 9 illustrates another embodiment different from FIG. 7.
The embodiment will be described focused on differences from FIG.
7.
[0071] Referring to FIG. 9, a transfer preventive unit includes a
fixed portion 393 fastened to the tub 20 for preventing deformation
caused by a load, and a free portion 391 formed as one body with
the fixed portion 393 for deforming which is caused by the
vibration of the stator to attenuate the vibration from the stator
to the tub 20. In this instance, since the free portion 391 is
connected to the insulator 450 to form a curve therewith, the free
portion 391 may reduce the vibration from the stator.
[0072] FIG. 10 illustrates another embodiment for preventing the
vibration from transferring from the stator 44 to the tub 20.
[0073] Referring to FIG. 10, the embodiment is provided with a
transfer preventive member 50 for preventing the transfer of
vibration when the stator 44 is fixed to the tub 20.
[0074] The transfer preventive member 50 is provided to the tub
fastening portion 193 and is connected to a fastening member, such
as a bolt, that fastens the tub fastening portion 193 to the tub 20
for preventing the vibration from transferring from the stator 44
to the tub 20.
[0075] That is, the transfer preventive member 50 is formed of an
elastic material, such as rubber, for preventing the vibration from
transferring from the stator 44 to the tub 20 through the bolt.
[0076] In the meantime, the vibration prevention units of the
embodiments in FIGS. 7 to 10, not only prevent the transfer of
vibration simply, but also serve to change a factor of the
vibration transfer function of the stator.
[0077] FIG. 11 illustrates a graph showing changes of the vibration
after the factor of the vibration transfer function of the stator
44, i.e., the natural frequency and/or the critical frequency is
changed.
[0078] In detail, if characteristics of the vibration transfer
function of the stator 44 is changed, the natural frequency fn and
the critical frequency fc of the transfer function drops. Owing to
this, overlap of a range .delta. with a range .beta. may be
prevented. Here, the vibration transfer rate of the stator 44 is
the maximum in the range .delta., and the maximum vibration
frequency in which the vibration of the rotor 42 becomes the
maximum falls in the range .beta..
[0079] Eventually, as shown in FIG. 12, the vibration of the
laundry machine 100 can be reduced distinctively. Actually, the
graph in FIG. 12 can be compared to the graph in FIG. 5, to find
that a range in FIG. 5 in which the vibration of the laundry
machine 100 becomes the maximum does not appear in FIG. 12.
[0080] In order to obtain the foregoing effects, it is required to
change the characteristic of the vibration transfer function of the
stator 44. By changing at least one of the natural frequency fn of
the stator 44 and the critical frequency fc of the transfer
function, the characteristic of the transfer function may be
changed.
[0081] In detail, in order to reduce the vibration of the laundry
machine 100, it is preferable not to make the range .beta. of the
rotor 42 to overlap with the range .delta. of the stator 44. To do
this, the critical frequency fc of the transfer function of the
stator 44 may be set smaller than the frequency of the range .beta.
of the rotor 42. Preferably, the critical frequency fc of the
transfer function of the stator 44 may be adjusted to be lower than
the maximum vibration frequency of the rotor 42.
[0082] In the meantime, for adjusting the critical frequency fc, it
is preferable to adjust the natural frequency fn of the stator 44.
That is, the transfer functions in FIGS. 4 and 11 are determined
according to the characteristic of the stator 44. In addition,
correlation between the natural frequency fn and the critical
frequency fc is fixed and according to the transfer function.
Accordingly, it is preferable that, by adjusting the natural
frequency fn of the stator according to the correlation between the
natural frequency fn and the critical frequency fc, the critical
frequency fc of the stator is adjusted to be lower than the maximum
vibration frequency of the rotor.
[0083] In parameters which influence the natural frequency fn of
the stator 44, there are mass m and elastic modulus k of the stator
44. Generally, the natural frequency fn is proportional to a square
root of a value corresponding to the elastic modulus divided by the
mass (fn .quadrature. (k/m)). Since the mass m of the stator 44 is
fixed according to a capacity of the motor and the like, in most of
cases, it is difficult for the mass m to be changed. Therefore, for
adjusting the natural frequency fn of the stator 44, it is
preferable that the elastic modulus of the stator 44 is changed. It
is preferable that the elastic modulus of the stator 44 is reduced
to reduce the natural frequency fn.
[0084] The elastic modulus of the stator 44 may be reduced by
different methods. For an example, a material of the stator may be
changed, or a structural change, such as an extension or an incised
portion, may be introduced to a part of the stator for changing the
elastic modulus of the stator 44. The embodiments described with
reference to FIGS. 7 to 10 not only prevent the vibration of the
stator 44 from transmission, but also change factors of the
vibration transfer function of the stator 44 by means of the
vibration transfer preventive unit.
[0085] In the meantime, FIG. 13 illustrates a structure according
to one embodiment for changing the natural frequency and/or the
critical frequency of the vibration transfer function of the stator
44, for example, to change the elastic modulus of the stator
44.
[0086] As shown, FIG. 13 illustrates a partial side sectional view
showing a structure the insulator 450 of the stator 44. In
particular, FIG. 13 illustrates the rear wall 22 of the tub 20
together with the insulator 450 of the stator 44.
[0087] Referring to FIG. 13, the insulator 450 of the stator 44 may
include an upper insulator 452 and a lower insulator 454, and the
stator core is provided in a space between the upper insulator 452
and the lower insulator 454.
[0088] The insulator 450 of the stator 44 is mounted to the rear
wall 22 of the tub 20. Therefore, the stator 44 is mounted to the
rear wall 22 of the tub 20, vertically. In the meantime, the rear
wall 22 of the tub 20 may not be formed flat, but curved for
reinforcement and mounting other elements thereto.
[0089] Accordingly, in an embodiment where the stator 44 is mounted
centered on a central portion of the rear wall 22 of the tub 20, an
underside surface is not in close contact with the rear wall 22 of
the tub 20 completely, but forms a gap with the rear wall 22.
Therefore, in the embodiment where the stator 44 is mounted to the
rear wall of the tub 20 vertically, if the gap is formed between
the underside surface of the stator 44 and the tub 20, the rear
wall 22 fails to fully support the stator 44, and in a case the
vibration takes place at the stator 44 due to driving of the motor
40, the vibration can be amplified. Particularly, in an embodiment
where only a central portion of the stator 44 is fixed to the rear
wall 22 of the tub 20, and a periphery of the stator 44, i.e., a
teeth portion 446 is not fixed, the vibration may be heavy.
[0090] Therefore, those embodiments may be provided with a
supporting member 460 on an underside of the insulator 450 of the
stator 44. The supporting member 460 connects the underside of the
insulator 450 to the rear wall 22 of the tub 20, to support the
stator 44. The supporting member 460 may be formed as one unit with
the insulator 450, or may be formed as an individual member and
mounted to the insulator 450.
[0091] In the meantime, if the supporting member 460 is provided, a
shape change of the insulator of the stator 44 may take place,
which may change the elastic modulus of the stator 44. Moreover, by
changing a thickness, a length and a number of the supporting
member, the natural frequency fn of the stator may be adjusted,
such that the critical frequency fc of the stator may be set to be
below the maximum vibration frequency of the rotor.
[0092] As has been described, the laundry machine according to
various embodiments may reduce noise and/or vibration without
requiring any additional element.
[0093] It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the inventions. Thus, it is intended that the
claims covers those modifications.
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