U.S. patent application number 14/173240 was filed with the patent office on 2014-08-07 for methods of operating washing machines and washing machines using the same.
This patent application is currently assigned to WHIRLPOOL CORPORATION. The applicant listed for this patent is WHIRLPOOL CORPORATION. Invention is credited to MASSIMO PAGLIA, GAETANO PAVIGLIANITI, MATTIA VAGO.
Application Number | 20140215725 14/173240 |
Document ID | / |
Family ID | 47681769 |
Filed Date | 2014-08-07 |
United States Patent
Application |
20140215725 |
Kind Code |
A1 |
PAGLIA; MASSIMO ; et
al. |
August 7, 2014 |
METHODS OF OPERATING WASHING MACHINES AND WASHING MACHINES USING
THE SAME
Abstract
Example methods of determining the degree of satellization of
laundry articles against an inner wall of a drum of a laundry
treating appliance are disclosed. An example method of operating a
laundry treating appliance having a rotatable drum defining a
treating chamber for receiving laundry for treatment, and a motor
rotating the drum includes increasing the rotational speed of the
drum by increasing the rotational speed of the motor, and detecting
when a parameter signal representing the rotation of the drum
reaches substantially a minimum to determine the speed at which
substantially all of the laundry is satellized.
Inventors: |
PAGLIA; MASSIMO; (Travedona
Monate, IT) ; PAVIGLIANITI; GAETANO; (Varese, IT)
; VAGO; MATTIA; (Busto Arsizio, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WHIRLPOOL CORPORATION |
Benton Harbor |
MI |
US |
|
|
Assignee: |
WHIRLPOOL CORPORATION
Benton Harbor
MI
|
Family ID: |
47681769 |
Appl. No.: |
14/173240 |
Filed: |
February 5, 2014 |
Current U.S.
Class: |
8/137 ;
68/12.02 |
Current CPC
Class: |
D06F 2222/00 20130101;
D06F 35/007 20130101; D06F 37/203 20130101; D06F 33/00 20130101;
D06F 2202/12 20130101 |
Class at
Publication: |
8/137 ;
68/12.02 |
International
Class: |
D06F 33/02 20060101
D06F033/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2013 |
EP |
13154334.0 |
Claims
1-11. (canceled)
12. A method of operating a laundry treating appliance having a
rotatable drum defining a treating chamber for receiving laundry
for treatment, and a motor rotating the drum, the method
comprising: increasing the rotational speed of the drum by
increasing the rotational speed of the motor; and detecting when a
parameter signal representing the rotation of the drum reaches
substantially a minimum to determine the speed at which
substantially all of the laundry is satellized.
13. A method as defined in claim 12, wherein the parameter signal
represents the energy of the motor.
14. A method as defined in claim 13, wherein the parameter signal
represents at least one of a motor torque and/or a motor power.
15. A method as defined in claim 12, wherein detecting when the
parameter signal reaches substantially the minimum comprises
monitoring a low frequency component of the parameter signal.
16. A method as defined in claim 12, further comprising filtering
the parameter signal to substantially remove a high frequency
component.
17. A method as defined in claim 12, further comprising after the
minimum is detected, waiting a predetermined time, and detecting
whether another minimum is found after detecting a maximum.
18. A laundry treating appliance comprising: a rotatable drum
defining a treating chamber for receiving laundry for treatment; a
motor rotating the drum; and a control unit programmed to, at
least, increase the rotational speed of the drum by increasing the
rotational speed of the motor, and detect when a parameter signal
representing the rotation of the drum reaches substantially a
minimum to determine the speed at which substantially all of the
laundry is satellized.
19. A laundry treating appliance as defined in claim 18, wherein
the parameter signal represents the energy of the motor.
20. A laundry treating appliance as defined in claim 19, wherein
the parameter signal represents at least one of a motor torque
and/or a motor power.
21. A laundry treating appliance as defined in claim 18, wherein
the control unit is programmed to detect when the parameter signal
reaches substantially the minimum by monitoring a low frequency
component of the parameter signal.
22. A laundry treating appliance as defined in claim 18, wherein
the control unit is programmed to filter the parameter signal to
substantially remove a high frequency component.
23. A laundry treating appliance as defined in claim 18, wherein
the control unit is programmed to, after the minimum is detected,
wait a predetermined time, and detect whether another minimum is
found after detecting a maximum.
Description
RELATED APPLICATION
[0001] This application claims priority from European Patent
Application No. 13154334.0 filed on Feb. 7, 2013, the entirety of
which is incorporated herein.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates generally to washing machines and,
more particularly, to determining the degree of satellization of
laundry articles against an inner wall of a drum.
BACKGROUND
[0003] A known method is described in EP 2379786, where the
measured parameter (e.g., a measurement variable or a control
variable) has a harmonic oscillation produced by an imbalance. This
known method requires a complex comparison between a theoretical
sinusoidal oscillation of the parameter and the actual oscillation,
so as to determine the degree of the satellization of the laundry
articles against the inner wall of the drum on the basis of the
correlation. This known method requires a complex algorithm capable
of carrying out such a correlation. Moreover, the degree of the
satellization of the laundry articles against the inner wall of the
drum, i.e., the percentage of load retained in a substantially
fixed position relative to the drum by centrifugal force, may be
considered too rich of information for the actual purpose of washer
control, because what matters is only the speed at which all
clothes in the drum of the washing machine are stuck to the side
wall of the drum by means of the centrifugal force effect. At this
speed, or at a speed incremented by a predetermined value with
reference to this speed, the unbalance determination can be safely
and quickly carried out without the need of reaching a fixed
predetermined value as in prior-art washing machines (i.e. saving
cycle time and energy). Moreover, carrying out imbalance detection
at a speed identical or very close to the actual speed at which
laundry is retained in a fixed position relative to the drum by
centrifugal force has advantages also in view of the accuracy and
robustness of unbalance detection.
SUMMARY
[0004] In view of the above, this disclosure provides simple,
reliable and inexpensive methods to detect the speed at which
laundry is retained in a substantially fixed position relative to
the drum by centrifugal force, so that substantially no portion of
load is allowed to tumble.
[0005] According to this disclosure, the above objects are reached
thanks to the features listed in the appended claims.
[0006] In this disclosure, any signal related to the energy of the
motor system, particularly torque or power thereof, is monitored
during an acceleration phase and the speed at which laundry
articles are satellized against the side wall of the drum due to
centrifugal force is detected when said signal reaches
substantially a minimum.
[0007] One advantage of the methods disclosed herein is that
complexity is dramatically reduced. Moreover, because the disclosed
methods are based on the physical behavior of the laundry inside
the drum (mechanical energy balance), the disclosed methods are
calibration free with respect to machine type/model variation. That
is, no additional effort is required to calibrate algorithm
parameters.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Further advantages and features of this disclosure will
become clear from the following detailed description, with
reference to the attached drawings, in which:
[0009] FIG. 1 is a diagram showing an example acceleration of a
drum used by the disclosed methods;
[0010] FIG. 2 shows an example distribution of laundry inside the
drum during the three specific phases identified in FIG. 1;
[0011] FIG. 3 shows an example balance of torque in the first phase
of FIGS. 1 and 2;
[0012] FIGS. 4-5 are similar to FIG. 3 and show example balances of
torque in the second and third phase of drum acceleration shown in
FIGS. 1 and 2;
[0013] FIG. 6 shows an example torque behavior during a
distribution profile with laundry;
[0014] FIG. 7 shows an example power signal behavior during a
distribution profile with laundry;
[0015] FIG. 8 is a block diagram of an example disclosed method;
and
[0016] FIG. 9 shows the example method of FIG. 8 in detail.
DETAILED DESCRIPTION
[0017] This disclosure relates to methods of operating laundry
treating appliances having a rotatable drum defining a treating
chamber for receiving laundry for treatment, and a motor rotating
the drum. More specifically, the disclosed methods comprise
increasing the rotational speed of the drum by increasing the
rotational speed of the motor, and measuring at least one parameter
representing the rotation of the drum/motor in order to determine
the degree of the satellization of the laundry articles against the
inner wall of the drum.
[0018] While the disclosed methods may be mainly used for washing
machines, they can be used also for, among other things, tumble
dryers and washer-dryers.
[0019] FIGS. 1 and 2, show an example acceleration speed profile
having three phases (I, II, III in FIGS. 1 and 2). During the first
two phases I and II the laundry inside the drum is tumbling. The
amount of laundry stuck on the side of the drum increases as the
speed increases, while the amount of tumbling laundry decreases.
This condition holds until the drum reaches the speed at which
substantially all laundry is stuck to the side of the drum (phase
III). This speed is known as "satellization speed".
[0020] This phenomenon is due to the increasing centrifugal force
as drum rotational speed increases. The mechanical torque that the
motor delivers during the distribution phases shown in FIGS. 1 and
2 will change according to the following findings, considering the
drum rotating counterclockwise.
[0021] Phase I (FIG. 3):
[0022] Laundry is tumbling. The motor torque must be enough to lift
up the amount of laundry inside the drum. An example mechanical
equation for phase I can be expressed as:
T.sub.mot.sub.I=T.sub.laundryI+b.sub.frict.omega..sub.IJ.sub.0{dot
over (.omega.)}
[0023] where T.sub.mot.sub.I is the motor torque, b.sub.frict is
the viscous friction coefficient, .omega. is the rotational speed
of the drum, J.sub.0 is the inertia momentum of the machine with
empty drum, and T.sub.laundry.sub.I is the torque due to the
gravity acceleration acting on non-satellized laundry and to the
inertia momentum of the laundry. This last term can be considered
as an additive friction torque amount that the motor need
overcome.
[0024] Phase II (FIG. 4):
[0025] As the speed increases, the centrifugal force increases and
laundry starts sticking on the drum side wall. The amount of
laundry when rotating in the left side of the drum starts to "help"
motor deliver the torque needed. So, the motor torque required
(T.sub.mot.sub.II) decreases.
T.sub.mot.sub.II+T.sub.laundry.sub.+=T.sub.laundry.sub.-+b.sub.frict.ome-
ga..sub.II+J.sub.0{dot over (.omega.)}
T.sub.mot.sub.II=(T.sub.laundry.sub.--T.sub.laundry.sub.+)+b.sub.frict.o-
mega..sub.II+J.sub.0{dot over (.omega.)}
T.sub.mot.sub.II=.DELTA.T.sub.laundry+b.sub.frict.omega..sub.II+J.sub.0{-
dot over (.omega.)}
where
T.sub.laundry.sub.->T.sub.laundry.sub.+T.sub.mot.sub.II<T.sub.mot.-
sub.I
Note Well:
[0026] T.sub.laundry.sub.I>>b.sub.frict.omega..sub.I
.DELTA.T.sub.laundry>>b.sub.frict.omega..sub.II
[0027] Phase III (FIG. 5):
[0028] Motor torque continues to decrease until the time at which
substantially all of the laundry is "plastered," "satellized," or
otherwise fixedly retained against the drum. The motor torque
reaches substantially its minimum at the satellization speed due to
the fact that when the laundry is completely stuck, the motor need
only lift up approximately half of the laundry amount (right side)
while the other half (left side) "helps" the motor to deliver
needed torque.
T.sub.mot.sub.III+T.sub.laundry.sub.2+=T.sub.laundry.sub.-+b.sub.frict.o-
mega..sub.sat+J.sub.sat{dot over (.omega.)}
T.sub.mot.sub.III=(T.sub.laundry.sub.2--T.sub.laundry.sub.2+)+b.sub.fric-
t.omega..sub.sat+J.sub.sat{dot over (.omega.)}
T.sub.mot.sub.III=b.sub.frict.omega..sub.sat+J.sub.sat{dot over
(.omega.)}+T.sub.frict
where
T.sub.laundry.sub.2-.apprxeq.T.sub.laundry.sub.2+T.sub.mot.sub.III<T.-
sub.mot.sub.II'
J.sub.sat=J.sub.0+J.sub.laundry.sub.--.sub.sat,
because when laundry is retained in a substantially fixed position
relative to the drum, geometry is substantially fixed as well and
remains approximately constant. T.sub.frict is a constant friction
torque.
[0029] Just after the laundry is retained in a substantially fixed
position relative to the drum by centrifugal force, the motor
torque (T.sub.mot) low frequency component increases linearly
because the viscous friction term increases with rotational
speed.
[0030] The mechanical equation can be expressed as follows:
T.sub.mot=b.sub.frict.omega.+J.sub.sat{dot over
(.omega.)}+T.sub.frict
[0031] FIG. 6 shows the substantially minimum reached by the low
frequency component of the torque when the "satellization speed" is
reached. The applicants observed that after "satellization speed"
the motor torque signal increases linearly due to the viscous term
of the above mechanical equation.
[0032] Disclosed example methods are the consequence of the above
findings to detect the "satellization speed" in a simple and
reliable way.
[0033] In some disclosed examples, during a speed acceleration
profile the torque low frequency component (or the average torque)
is processed and, when the substantially minimum is found, the
corresponding reached speed is the "satellization speed".
[0034] In some disclosed examples, the signal processed to detect
the "satellization speed" is a mechanical/electrical power signal
relative to the energy of the motor, where the mechanical power is,
for example the signal shown in FIG. 7.
[0035] Because the power is the torque multiplied by the speed, the
position of substantially the minimum is highlighted in FIG. 7.
That's because power (P.sub.mot) shows a parabolic behavior:
P.sub.motT.sub.mot.omega.=(b.sub.frict.omega.+J.sub.sat{dot over
(.omega.)}+T.sub.frict).omega.=b.sub.frict.omega..sup.2+J.sub.sat{dot
over (.omega.)}T.sub.frict.omega.
[0036] On the other hand, the robustness of the disclosed methods
with respect to the friction term (b.sub.frict.omega..sup.2)
decreases.
[0037] As mentioned above, the main signal processed by the
disclosed methods is preferably the low frequency component of the
real signal. Accordingly, the disclosed methods find substantially
the minimum by processing the real signal filtered with a low pass
filter, with a "sliding moving average," or with any other method
which eliminates the high frequency components.
[0038] With reference to FIG. 8, an example method includes
monitoring the input main signal (torque/power etc.), waiting until
substantially the minimum occurs, and, when the minimum occurs,
getting the actual speed value and setting it as the "satellization
speed".
[0039] As disclosed above, a solution to detect substantially the
minimum is to process the torque (or power) signal with a suitable
digital filter (e.g., a "robust noise differentiator" technique)
and compare values to get minima and maxima.
[0040] However, FIG. 7 shows that the low frequency component of
the power (or torque) signal could present a local minima due to
the laundry tumbling and inertia geometry variation during
distribution. To avoid misclassifying minima, disclosed methods
wait preferably a predefined time (machine model dependent) and
monitor if a new maximum is found (i.e., due to the physical
behavior of the laundry inside the drum, if a maximum happens a new
minimum will come).
[0041] FIG. 9 shows such a variant of the minimum search algorithm
in the details.
[0042] Experiments carried out by the applicants on a washer
machine have shown that the disclosed methods are very reliable,
and that the effect of variation of the viscous friction
coefficient is negligible.
* * * * *