U.S. patent application number 11/605978 was filed with the patent office on 2008-05-29 for cloth bunching detection and adjustment for an automatic washer.
Invention is credited to Farhad Ashrafzadeh, Flavio Bernardino, Kalyanakrishnan Vadakkeveedu, Raveendran Vaidhyanathan, Mary Ellen Zeitler.
Application Number | 20080120789 11/605978 |
Document ID | / |
Family ID | 39462205 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080120789 |
Kind Code |
A1 |
Ashrafzadeh; Farhad ; et
al. |
May 29, 2008 |
Cloth bunching detection and adjustment for an automatic washer
Abstract
A method and apparatus for determining the bunching of fabric
items during a wash process.
Inventors: |
Ashrafzadeh; Farhad;
(Stevensville, MI) ; Vadakkeveedu; Kalyanakrishnan;
(College Station, TX) ; Vaidhyanathan; Raveendran;
(St. Joseph, MI) ; Zeitler; Mary Ellen; (St.
Joseph, MI) ; Bernardino; Flavio; (St. Joseph,
MI) |
Correspondence
Address: |
WHIRLPOOL PATENTS COMPANY - MD 0750
Suite 102, 500 Renaissance Drive
St. Joseph
MI
49085
US
|
Family ID: |
39462205 |
Appl. No.: |
11/605978 |
Filed: |
November 29, 2006 |
Current U.S.
Class: |
8/159 ;
68/12.02 |
Current CPC
Class: |
D06F 23/00 20130101;
D06F 34/18 20200201 |
Class at
Publication: |
8/159 ;
68/12.02 |
International
Class: |
D06F 37/30 20060101
D06F037/30; D06F 21/00 20060101 D06F021/00 |
Claims
1. A method for determining the degree of bunching of fabric
articles in an automatic washer comprising a wash tub in which is
disposed a wash basket defining a wash chamber configured to
receive the fabric articles and an article mover located within the
wash chamber and reciprocally driven by a motor between a forward
stroke and backward stroke to impart mechanical energy to the
fabric articles, the method comprising: determining a
characteristic of a waveform for at least one of the motor speed
and motor current for each of the forward and backward strokes; and
determining the degree of bunching by comparing the determined
characteristic for each of the forward and backward strokes.
2. The method according to claim 1 wherein determining the
characteristic comprises determining an amplitude of the waveform
for each of the forward and backward strokes.
3. The method according to claim 2 wherein the comparing of the
amplitudes comprises determining the difference between the
amplitudes of the motor current waveform.
4. The method according to claim 3 wherein the difference is
compared to a threshold value to determine the degree of
bunching.
5. The method according to claim 3 wherein the comparing of the
amplitudes comprises determining the mean square of the difference
between the amplitudes.
6. The method according to claim 3 wherein the difference between
the amplitudes is determined for multiple pairs of the forward and
backward strokes.
7. The method according to claim 6 wherein the comparing of the
amplitudes comprises determining the mean square of the differences
for the multiple pairs of forward and backward strokes.
8. The method according to claim 6 wherein the multiple differences
are averaged.
9. The method according to claim 8 wherein the average is compared
to a threshold value to determine the degree of bunching.
10. The method according to claim 3 wherein the determining the
difference of the amplitudes comprises at least one of determining
a difference between a current wave form for each of the forward
and backward strokes and determining a difference between a point
of each of the waveforms for the forward and backward strokes.
11. The method according to claim 2 wherein the determining of the
amplitudes comprises determining amplitudes at the same relative
time for each of the forward and backward strokes.
12. The method according to claim 11 wherein the comparing of the
amplitudes comprises determining the difference between the
amplitudes.
13. The method according to claim 12 wherein the difference is
compared to a threshold value to determine the degree of
bunching.
14. The method according to claim 12 wherein the comparing of the
amplitudes comprises determining the mean square of the difference
between the amplitudes.
15. The method according to claim 12 wherein the difference between
the amplitudes is determined for multiple pairs of the forward and
backward strokes.
16. The method according to claim 15 wherein the comparing of the
amplitudes comprises determining the mean square of the differences
for the multiple pairs of forward and backward strokes.
17. The method according to claim 15 wherein the multiple
differences are averaged.
18. The method according to claim 17 wherein the average is
compared to a threshold value to determine the degree of
bunching.
19. The method according to claim 1 wherein determining the
characteristic comprises determining a frequency of the waveform
for each of the forward and backward strokes.
20. The method according to claim 19 wherein the comparing of the
frequencies comprises determining the difference between the
frequencies.
21. The method according to claim 20 wherein the difference is
compared to a pre-determined value.
22. The method according to claim 19 and further comprising
repeating the determination of the frequencies for multiple forward
strokes and backward strokes.
23. The method according to claim 22 and further comprising
determining an average frequency for the forward strokes and an
average frequency for the backward strokes.
24. The method according to claim 23 wherein the comparing the
determined frequencies comprises comparing the average
frequencies.
25. The method according to claim 24 wherein the comparing of the
frequencies comprises determining the difference between the
average frequencies.
26. The method according to claim 25 wherein the difference is
compared to a pre-determined value.
27. The method according to claim 22 wherein the determining of the
frequency comprises determining an average frequency for the
forward strokes and an average frequency for the backward
strokes.
28. The method according to claim 27 wherein the comparing the
determined frequencies comprises comparing the average
frequencies.
29. The method according to claim 28 wherein the comparing of the
frequencies comprises determining the difference between the
average frequencies.
30. A method for controlling the operation of an automatic washer
comprising a wash tub in which is disposed a wash basket defining a
wash chamber configured to receive fabric articles and an article
mover located within the wash chamber and reciprocally driven by a
motor between a forward stroke and backward stroke to impart
mechanical energy to the fabric articles, the method comprising:
determining a characteristic of a waveform for at least one of the
speed and current for the motor for each of the forward and
backward strokes; determining the bunching of the fabric articles
from the determined characteristics; and controlling an operating
cycle of the automatic washer based on the determined
characteristics.
31. The method according to claim 30 wherein the determining of the
bunching comprises comparing the characteristics.
32. The method according to claim 31 wherein the determining a
characteristic comprises determining an amplitude of the motor
current waveform for each of the forward and backward strokes.
33. The method according to claim 32 wherein the comparing of the
characteristics comprises comparing the amplitudes by determining
the difference between the amplitudes.
34. The method according to claim 33 wherein the difference is
compared to a threshold value to determine the degree of
bunching.
35. The method according to claim 33 wherein the comparing of the
amplitudes comprises determining the mean square of the difference
between the amplitudes.
36. The method according to claim 33 wherein the difference between
the amplitudes is determined for multiple pairs of the forward and
backward strokes.
37. The method according to claim 36 wherein the comparing of the
amplitudes comprises determining the mean square of the differences
for the multiple pairs of forward and backward strokes.
38. The method according to claim 36 wherein the multiple
differences are averaged.
39. The method according to claim 36 wherein the average is
compared to a threshold value to determine the degree of
bunching.
40. The method according to claim 36 wherein the determining the
difference of the amplitudes comprises at least one of determining
a difference between a current wave form for each of the forward
and backward strokes and determining a difference between a point
of each of the waveforms for the forward and backward strokes.
41. The method according to claim 32 wherein the determining of the
amplitudes comprises determining an amplitude at the same relative
time for each of the forward and backward strokes.
42. The method according to claim 41 wherein the comparing of the
amplitudes comprises determining the difference between the
amplitudes.
43. The method according to claim 42 wherein the difference is
compared to a threshold value to determine the degree of
bunching.
44. The method according to claim 42 wherein the comparing of the
amplitudes comprises determining the mean square of the difference
between the amplitudes.
45. The method according to claim 42 wherein the difference between
the amplitudes is determined for multiple pairs of the forward and
backward strokes.
46. The method according to claim 45 wherein the comparing of the
amplitudes comprises determining the mean square of the differences
for the multiple pairs of forward and backward strokes.
47. The method according to claim 45 wherein the multiple
differences are averaged.
48. The method according to claim 47 wherein the average is
compared to a threshold value to determine the degree of
bunching.
49. The method according to claim 30 wherein the controlling of the
operating cycle comprises adjusting at least one of the impeller
stroke and water level in the wash chamber.
50. The method according to claim 49 and further comprises
adjusting of the operating cycle after at least one pair of strokes
and after many multiple pairs of strokes.
51. The method according to claim 49 and further comprises
immediate adjustment of the operating cycle when the bunching is
determined to be very high.
52. The method according to claim 51 wherein the adjustment of the
operating cycle comprises stopping the cycle.
53. The method according to claim 49 wherein the adjusting of the
impeller stroke comprises at least one of increasing the speed and
shortening the length of the impeller stroke
54. The method according to claim 49 wherein the adjusting of the
water level in the wash chamber comprises increasing the water
level in at least one of the wash chamber and wash basket.
55. The method according to claim 31 wherein determining the
characteristic comprises determining a frequency for each of the
forward and backward strokes.
56. The method according to claim 55 and further comprising
repeating the determination of the frequencies for multiple forward
strokes and backward strokes.
57. The method according to claim 56 and further comprising
determining an average frequency for the forward strokes and an
average frequency for the backward strokes.
58. The method according to claim 57 wherein the comparing the
determined frequencies comprises comparing the average
frequencies.
59. The method according to claim 58 wherein the comparing of the
frequencies comprises determining the difference between the
average frequencies.
60. The method according to claim 55 wherein the determining of a
frequency comprises determining an average frequency for each of
the forward and backward strokes.
61. The method according to claim 60 wherein the determining of the
bunching comprises comparing the determined average
frequencies.
62. The method according to claim 61 wherein the comparing of the
frequencies comprises determining the difference between the
average frequencies.
63. The method according to claim 62 wherein the difference is
compared to a pre-determined value.
64. An automatic clothes washer comprising: a wash chamber for
receiving fabric items; a clothes mover located within the wash
chamber; a motor operably coupled to the clothes mover to move the
clothes mover relative to the wash chamber; and a sensor configured
to determine the degree of bunching of the fabric items in the wash
chamber.
65. The automatic clothes washer according to claim 64, wherein the
sensor is a real-time sensor.
66. The automatic clothes washer according to claim 65, wherein the
real-time sensor comprises at least one of a motor speed sensor and
motor current sensor.
67. The automatic clothes washer according to claim 66, wherein the
real-time sensor further comprises a controller configured to
receive an output from one of the motor speed sensor and the motor
current sensor.
68. The automatic clothes washer according to claim 67, wherein the
controller is configured to determine the degree of bunching from
the output.
69. The automatic clothes washer according to claim 70, wherein the
output is a determined characteristic of a waveform for at least
one of the motor speed and motor current for each of the forward
and backward strokes.
70. The method according to claim 69 wherein determining the
characteristic comprises determining the amplitude from the motor
current sensor.
71. The method according to claim 69 wherein determining the
characteristic comprises determining the frequency from at least
one of the motor current sensor or the motor speed sensor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method for detecting the degree
of bunching of articles in an automatic clothes washer. The
inventions further relates to methods of adjustment to reduce the
degree of bunching.
[0003] 2. Description of the Related Art
[0004] Automatic clothes washers are ubiquitous. Such appliances
clean fabric items effectively, enabling the homeowner to complete
other tasks or engage in more satisfying activities while doing the
laundry. Modern clothes washers provide a multitude of options for
matching a selected cleaning operation to the type of fabric
comprising the laundry load and the degree of soiling of the
laundry load. This includes setting a liquid level appropriate to
the size and fabric type of the laundry load. Modern clothes
washers also include sophisticated controllers that are programmed
to maximize cleaning efficiency while minimizing water and power
consumption. However, despite the capabilities of the modern
clothes washer, the appliance remains limited in its ability to
detect bunching and then adjust the wash cycle based on real-time
information relating to the fabric items being washed.
[0005] One type of conventional automatic clothes washer may be
provided with a drive motor, generally electrically powered, which
may be used to drive a cylindrical perforate basket during a spin
cycle, and a clothes mover during wash and rinse cycles for
agitating the laundry load within the basket.
[0006] In a conventional automatic clothes washer, cleaning of the
fabric items may be primarily attributable to three factors:
chemical energy, thermal energy, and mechanical energy. These three
factors may be varied within the limits of a particular automatic
clothes washer to obtain the desired degree of cleaning.
[0007] The chemical energy relates to the types of wash aids, e.g.
detergent and bleach, applied to the fabric items. All other things
being equal, the more wash aid used, the greater will be the
cleaning effect.
[0008] The thermal energy relates to the temperature of the fabric
items. The temperature of the wash liquid typically constitutes the
source of the thermal energy. However, other heating sources may be
used. For example, one known way uses steam to heat the fabric
items. All things being equal, the greater the thermal energy, the
greater will be the cleaning effect.
[0009] The mechanical energy may be attributed to the contact
between the clothes mover and the fabric items, the contact between
the fabric items themselves, and the passing of the washing liquid
through the fabric items. In washing machines with a fabric mover,
the fabric mover tends to cause the fabric items to contact
themselves, and for the wash liquid to pass through the fabric
items. All things being equal, the greater the amount of mechanical
energy, the greater will be the cleaning effect.
[0010] These three factors may be adjusted to obtain the desired
cleaning effect. For example, while the direct contact between the
clothes mover and the fabric items may be beneficial for
laundering, it does cause greater physical wearing of the fabric
items than the other two factors. Thus, for example, for more
delicate clothing, it may be desired to reduce the direct contact.
However with contemporary washing machines, it has not yet been
possible to determine the mechanical energy imparted to the fabric
items during the washing process. Thus, contemporary solutions are
based on estimates or empirical data, both of which are typically
determined based on a set of standard test conditions.
Unfortunately, these standard test conditions are not guaranteed to
be repeated when the consumer uses the clothes washer, resulting in
a compromised cleaning result. It would be advantageous to the
overall cleaning performance if the mechanical energy imparted to
the fabric items could be determined during the washing
process.
SUMMARY OF THE INVENTION
[0011] A method and apparatus for determining the degree of
bunching of fabric items during a wash process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In the drawings:
[0013] FIG. 1 is a partially cut away elevational view of an
automatic clothes washer according to the invention illustrating
relevant internal components thereof, including a clothes basket,
and a clothes mover.
[0014] FIG. 2 is a partially cut away perspective view of the
clothes basket and clothes mover illustrated in FIG. 1.
[0015] FIG. 3 is a partially cut away enlarged view of the clothes
basket and clothes mover illustrated in FIG. 2 showing an article
of clothing in a first configuration relative to the clothes
mover.
[0016] FIG. 4 is a view of the clothes basket and clothes mover
illustrated in FIG. 3 showing the article of clothing in a second
configuration relative to the clothes mover.
[0017] FIG. 5 is a view of the clothes basket and clothes mover
illustrated in FIG. 3 showing the article of clothing in a third
configuration relative to the clothes mover.
[0018] FIG. 6 is a schematic representation of fabric items in an
un-bunched state in the cloths basket.
[0019] FIG. 7 is a schematic representation of fabric items in a
bunched state in the cloths basket.
[0020] FIG. 8 is a first graphical representation of motor speed
and motor current for the automatic clothes washer illustrated in
FIG. 1 containing only liquid during a single cycle of the clothes
mover consisting of a forward rotational stroke followed by a
backward rotational stroke.
[0021] FIG. 9 graphically represents the motor speed and motor
current for the automatic clothes washer illustrated in FIG. 1
containing liquid and a laundry load without bunching during a
single cycle of the clothes mover consisting of a forward
rotational stroke followed by a backward rotational stroke.
[0022] FIG. 10 graphically represents the motor speed and motor
current for the automatic clothes washer illustrated in FIG. 1
containing liquid and a laundry load with bunching during a single
cycle of the clothes mover consisting of a forward rotational
stroke followed by a backward rotational stroke.
DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
[0023] The invention relates to a method of determining the degree
of bunching of articles in a clothes washer based upon the
mechanical energy imparted to the fabric items by the engagement of
a clothes mover with fabric items in a laundry load. The invention
may also include a method for adjusting the wash cycle based on the
determined bunching. The method utilizes operational
characteristics of a drive motor, such as current and speed, to
determine the degree of bunching of the clothes articles. The
degree of bunching of the clothes articles may be compared with
pre-determined threshold for the degree of bunching to control the
operating cycle by introduction of liquid to the clothes washer, by
setting the agitator stroke, or by stopping the cycle.
[0024] Conventional automatic clothes washers enable a user to
select one of several laundering options based upon the type of
laundry load being placed in the clothes washer. For example,
selectable options may include "normal," "delicates," "woolens,"
and the like. These are typically referred to as "cycles." As
utilized herein, "laundering cycle" will refer to a specific cycle,
such as "normal," extending from the beginning of the cycle to its
completion. A laundering cycle will generally consist of at least a
wash cycle, a rinse cycle, and a spin cycle. The wash cycle, the
rinse cycle, and the spin cycle may consist of several steps, such
as a fill step, a drain step, a pause step, an agitation step, and
the like. The invention may be used with any cycle regardless of
the types and combination of steps.
[0025] FIG. 1 illustrates an embodiment of the invention consisting
of a vertical axis automatic clothes washer 10 comprising a cabinet
12 having a control panel 14, and enclosing a liquid-tight tub 16
defining a wash chamber in which may be located a perforate basket
18. Thus, fabric items placed in the basket 18 are placed in the
wash chamber. A clothes mover 20 adapted for imparting movement to
a laundry load contained within the basket 18 may be disposed in
the bottom of the basket 18. The clothes mover 20 illustrated has a
low profile vertical axis impeller. However, the clothes mover 20
may also be a vertical axis agitator, with or without an auger, or
a basket adapted with peripheral vanes. The clothes mover 20 and
basket 18 may be coaxially aligned with respect to a vertically
oriented oscillation axis 22.
[0026] While the invention will be illustrated with respect to a
low profile impeller, other clothes movers may be utilized without
departing from the scope of the invention. For example, it has been
contemplated that the invention has applicability to horizontal
axis washers as well as to the vertical axis washers. For purposes
of this application, horizontal axis washer refers to those types
of washers that move the fabric items primarily by lifting the
fabric items and letting them fall by gravity, regardless of
whether the axis of rotation remains primarily horizontal, and
vertical axis washer refers to those types of washers that move
fabric items by a clothes mover, regardless of whether the axis of
rotation remains primarily vertical.
[0027] The clothes mover 20 may be operably coupled with a drive
motor 28 through an optional transmission 26 and drive belt 30. One
or more well-known sensors 31 for monitoring angular velocity,
current, voltage, and the like, may be operably coupled with the
motor 28. Outputs from the sensors 31 may be delivered to a machine
controller 32 in the control panel 14. In many applications, the
sensors 31 form part of a motor controller coupled with the machine
controller 32. The machine controller 32 may be adapted to send and
receive signals for controlling the operation of the clothes washer
10, receiving data from the sensors 31, processing the data,
displaying information of interest to a user, and the like.
[0028] The clothes washer 10 may also be coupled with a source of
water 34 which may be delivered to the tub 16 through a nozzle 36
controlled by a valve 38 operably coupled with the machine
controller 32. The valve 38 and the machine controller 32 may
enable a precise volume of water to be delivered to the tub 16 for
washing and rinsing.
[0029] FIG. 2 illustrates an embodiment of the invention with the
clothes basket 18 and the clothes mover 20 in coaxial alignment
with the oscillation axis 22. The clothes mover 20 may be a
somewhat circular, plate like body having a plurality of radially
disposed vanes 40 extending upwardly therefrom. The vanes 40 may be
adapted to contact and interact with fabric items and liquid in the
basket 18 for agitating the fabric items and the liquid. During a
wash cycle and a rinse cycle, the clothes mover 20 may be driven by
the drive motor 28 for movement within the wash chamber. The basket
18 may be braked to remain stationary during the movement of the
clothes mover 20, or the basket 18 may freely rotate during the
movement of the clothes mover 20.
[0030] The drive motor 28 may drive the clothes mover 20 in an
oscillating manner, first in a forward direction, referred to
herein as a forward stroke, then in a backward direction, referred
to herein as a backward stroke. The clothes mover 20 may move in a
forward direction through a pre-selected angular displacement, for
example ranging from 180.degree. to 720.degree.. The clothes mover
20 may move in a backward direction through a similar pre-selected
angular displacement. A complete forward stroke and backward stroke
are referred to herein as an oscillation cycle.
[0031] For clothes movers that move rotationally, the forward and
backward strokes are often referred to as the clockwise and
counterclockwise strokes. While typically the forward stroke
constitutes the clockwise stroke and the backward stroke
constitutes the counterclockwise stroke, these relationships may
easily be reversed.
[0032] In a typical wash cycle, multiple fabric items, which
collectively form a laundry load, are placed in the basket on top
of the clothes mover 20. Some of the fabric items will be in direct
contact with the clothes mover 20 and some will not. As the clothes
mover 20 moves, the individual fabric items will be moved directly
or indirectly by the clothes mover 20 to impart mechanical energy
to the items, which will move the fabric items about the interior
of the wash chamber.
[0033] In FIG. 3, an embodiment of the invention shows a single
fabric item 50 in a lower portion of a laundry load will be in
contact with the clothes mover 20. The illustration does not
include liquid for clarity; however, it should be understood that
liquid exists and it may be at any level from just wetting the
fabric items to fully submerging the fabric items. The fabric item
50 may be represented by a downwardly directed weight factor 52.
The vanes 40 terminate in an upper vane edge 54. All or part of the
vane 40 may contact the fabric item 50 during the forward and
backward strokes of the clothes mover 20. As the clothes mover 20
rotates in a forward stroke, represented by the motion vector 42, a
vane 40 may be brought into contact with the fabric item 50.
[0034] FIG. 4 shows an embodiment where the contacting of the vane
40 with the single fabric item 50 tends to move the fabric item 50
in the direction of rotation of the clothes mover 20, represented
by the pull vector 56. The illustration does not include liquid for
clarity; however, it should be understood that liquid exists and it
may be at any level from just wetting the fabric items to fully
submerging the fabric items. Because of the weight of the fabric
item 50, the weight of overlying fabric items, the frictional
relationship between the fabric item 50 and the vane edge 54, the
degree of wetting of the fabric item 50, and other factors, there
may be intermittent grabbing and slipping by the vane 40 relative
to the fabric item 50 which will be reflected in movement of the
fabric item 50 that may not be the same rotational distance as the
clothes mover 20, resulting in relative movement between the fabric
item 50 and the clothes mover 20. As illustrated in FIG. 5, if
sufficient slippage exists, at some point during the forward stroke
the vane 40 may separate from the fabric item 50.
[0035] The intermittent grabbing and slipping of the vane 40 with
respect to the clothes mover 20 results in an intermittent
application of the weight of the fabric item 50 to the clothes
mover 20, which amounts to a loading and unloading of the clothes
mover 20. The loading and unloading present themselves as a change
in speed of the clothes mover 20, this may be sensed by the sensors
31. In response, the controller 32, which typically tries to move
the motor 28 at a predetermined set speed for the given cycle, will
increase or decrease the current to the motor 28 to attempt to
maintain the set speed.
[0036] The magnitude and frequency of grabbing and slipping may be
impacted by several factors, only some of which will now be
described. The greater the size laundry load, the greater will be
the weight of other fabric items bearing on the fabric item in
direct contact with the clothes mover 20. The increased volume of
the greater laundry load will also tend to inhibit the free
movement of the fabric items within the wash chamber.
[0037] Wet fabric items tend to create greater frictional
resistance with the clothes mover than dry fabric items. However,
as liquid level increases in the wash chamber to the point where
the fabric items are fully submerged, the additional liquid brings
into effect the buoyancy of the fabric items, which has an opposite
effect than the weight force of the fabric items. In some
instances, the liquid may be sufficiently deep and the clothes
mover may sufficiently agitate the liquid that some or all of the
fabric items are suspended in the liquid above the clothes mover
20, which will greatly reduce the loading of the clothes mover 20
by the fabric items. Thus, all things being equal, the deeper the
liquid, the greater the degree of loading and unloading will be
minimized.
[0038] Additional wash liquid also tends to interfere with the
clothes mover's 20 ability to reverse the direction of the fabric
items when the clothes mover 20 switches direction between the
forward and backward strokes. For example, when the clothes mover
20 moves in a forward stroke, it causes not only the fabric items
to move in the forward stroke direction, but also the liquid in the
wash chamber to move in a forward stroke direction. Upon reversing
to the backward stroke, fabric items in direct contact with the
clothes mover 20 will tend to follow the reverse stroke direction
of the clothes mover 20. However, the liquid, especially the liquid
above the clothes mover 20, will tend to maintain movement in the
forward stroke direction because of its momentum. Thus, the
reversal of the clothes mover 20 does not necessarily result in all
of the fabric items and liquid in the washer chamber reversing
direction in time with the clothes mover 20.
[0039] FIG. 6 constitutes a schematic representation of a fabric
load comprising fabric items 2 shown in an un-bunched state. Fabric
items 2 are considered not bunched where they are relatively
uniformly distributed in the wash liquid 4 in the wash basket 18.
Uniform distribution may be desired for optimum efficiency and
effective cleaning. The uniform distribution allows the cloth mover
20 to move forwards and backwards and allows for blooming of the
fabric items. Blooming is the turning over of the fabric items in
the wash load and is desired as it promotes uniform cleaning of the
fabric items. A common form of blooming occurs when the fabric
items move between the bottom of the basket to the top of the
liquid. This movement can also include the fabric items moving
radially inward and outward from the center of the basket to the
peripheral wall of the basket.
[0040] In FIG. 7, fabric items 2 may become bunched during the wash
cycle. During the wash cycle the bunched fabric items 3 become
bunched to one side and are no longer uniformly distributed within
the wash basket 18. Bunching may be thought of as several of the
fabrics items operably coupled such that they effectively behave as
a single mass. This may cause asymmetrical loading on the clothes
mover. The operable coupling may arise for one or more reasons,
examples include: the fabric items may be in an overlapped
condition and their weight and/or frictional resistance tends to
maintain the overlapped condition; the fabric items may be
intertwined or wrapped around each other; and the fabric items may
be twisted together.
[0041] Bunching of the fabric items in the wash basket 18 may have
several different disadvantageous effects in the clothes washer 10.
For example, one common disadvantage may be that the mechanical
energy imparted to the fabric items by the clothes mover 20 may be
focused primarily on the outside of the bunched fabric articles,
which minimizes the cleaning effect to the interior fabric
articles. The cleaning effect may be reduced because the wash
liquid 4 may not pass through the bunched fabric items 3 as easily
as if the clothes were more uniformly distributed. The cleaning
effect may also be reduced because the bunched fabric items 3 are
not able to move relative to each other and impart mechanical
energy to each other.
[0042] The bunched clothes may also move asymmetrically within the
wash basket even though the clothes mover typically rotates the
same distance for both the forward and backward strokes. The
phenomena of asymmetrically moving clothes occurs because the
bunched clothes load has a greater inertia than an evenly
distributed load and may be less likely to change direction of
rotation along with the clothes mover. The phenomena may more
easily occur as the liquid fill level increases in the wash chamber
because the increase in the buoyancy force decreases the weight of
the bunched clothes acting on the clothes mover, which makes it
easier for the bunched clothes to separate from the clothes mover.
The increased liquid further increases the likelihood of
asymmetrical clothes movement because as the liquid rises farther
above the clothes mover, the liquid may be less responsive to the
movement of the clothes mover. For example, the liquid immediately
adjacent the clothes mover may be very responsive to the movement
of the clothes mover and tends to follow its direction. The further
the liquid may be from the clothes mover, the less responsive it
may be as the intervening liquid must transfer the forces from the
clothes mover. The liquid also has its own inertia. Thus, once set
in motion by the clothes mover the liquid as it gets farther away
from the clothes mover will not be as greatly affected by the
change of direction of the clothes mover. While either the bunched
clothes or deeper fill may cause an asymmetrical movement of the
clothes, the combined effect of bunched clothing in deeper fill
wash cycles makes it more likely the bunched clothes will not
follow the movement of the clothes mover. In some cases, the effect
may be great enough that the bunched clothes generally move in only
one direction in the wash tub. When the bunched clothing does not
respond to the clothes mover, the cleaning of the bunched clothes
may be reduced as there may be less mechanical energy imparted to
the bunched clothes from the impeller, from reduced liquid flow
through the clothes, and from less clothes-to-clothes contact.
[0043] Bunching may be further disadvantageous in that during
either washing operations, where the clothes mover reciprocates, or
spinning operations, where the wash basket rotates, but especially
during the spinning operations, the bunched clothing may cause an
out of balanced condition great enough for the wash basket to
bottom out its suspension and/or contact a portion of the cabinet
12, which may be very undesirable.
[0044] Bunching may also slow the motor as the impeller blades of
the clothes mover contacts the bunched fabric items. In response,
the controller 32, which typically tries to move the motor 28 at a
predetermined set speed for the given cycle, will increase the
current to the motor 28 to attempt to increase the torque and
maintain the set speed. The additional motor current results in
increased costs to the consumer.
[0045] FIG. 8 graphically illustrates a waveform of the motor speed
70 and the motor current 72 during one oscillation cycle of the
clothes mover 20 through a forward stroke, represented by a forward
direction region 74, followed by movement in a backward stroke,
represented by a backward direction region 76. The waveforms of
FIG. 8 are generated by sampling the motor speed 70 and motor speed
current 72 at a predetermined interval or sampling rate, which in
this case constitutes 20 milliseconds.
[0046] As illustrated, in the forward direction region 74 the
clothes mover 20 may be quickly accelerated to a predetermined set
speed 74a, maintained at the predetermined set speed 74b, and then
quickly decelerated 74c, which may include braking, prior to
reversing. Region 74b may often be referred to as the plateau. The
backward direction region 76 may be similarly divided into an
acceleration step 76a, a plateau 76b, and a deceleration step 76c.
Thus, when the clothes mover 20 transitions from the forward stroke
to the backward stroke, the motor current 72 decreases to a zero
value 94, and the motor speed 70 responsively decreases to a zero
or nearly zero value 96. While the decrease in speed may not be
shown going to zero in FIG. 8, this results from the sampling rate
for the data points--the zero speed was not sampled--not an
indication that the speed does not go to zero. In reality, whenever
the clothes mover changes direction, there must be necessarily a
point, which might be instantaneous, where the speed equals
zero.
[0047] During the forward and backward strokes as illustrated in
FIG. 8, the controller controls the speed of the motor in an
attempt to maintain the motor speed at a predetermined set speed,
which for the example in FIG. 8 constitutes 110 rpm. Thus, the
speed of the clothes mover 20 remains essentially constant at
approximately the 110 RPM set speed in the plateau 74b, 76b of the
curve 70. There are nominal variations or ripples in the magnitude
of the motor current and motor speed in the plateaus 74b, 76b due
to the nominal loading and unloading of the liquid on the clothes
mover 20 associated with the engagement of the clothes mover 20
with the liquid as the clothes mover 20 moves through the liquid.
This loading and unloading transmits through the clothes mover 20
and the transmission 26 to the drive motor 28 where it may be
sensed by the speed sensor 31. The loading and unloading causes
temporary changes in the speed of the clothes mover 20 relative to
the set speed. In response, the controller 32 adjusts the current
to the motor 28 in an attempt to maintain the set speed, which
results in the motor current leading the speed as may be easily
seen in FIG. 8.
[0048] FIG. 9 graphically illustrates the waveforms for the motor
current 72 and motor speed 70 signals attributable to the loading
and unloading of the clothes mover 20 when there exists a load of
generally well distributed fabric items 50 in the wash chamber for
one oscillation cycle of the clothes mover 20. FIG. 9 illustrates
the waveforms of the motor speed 70 and motor current 72 where the
motor speed set point constitutes 120 rpm and the sampling rate
equals 20 milliseconds. The intermittent grabbing and slipping of
the fabric items 50 with the vanes of the clothes mover 20
transmits through the clothes mover 20 and the transmission 26 to
the drive motor 28, where it manifests as ripples in the waveforms
of both the motor speed and motor current. These ripples define a
waveform having multiple peaks. The peaks have greater magnitude
than those ripples in FIG. 8 because of the greater force
associated with the laundry load as compared to the liquid alone. A
peak in the waveform is an indication of the engagement between the
clothes and the impeller and does not illustrate bunching.
[0049] Looking more closely at the ripples of the motor speed
waveform in a fairly well distributed load, the ripples may be
separated into peaks comprising both positive peaks 82a-d, 86a-d
and negative peaks 84a-d, 88a-d. The amplitude or magnitude of the
ripples may be determined by comparing the peaks to the motor speed
set point. For example, the difference between the positive speed
amplitude 82 and the target rotation speed may be a first amplitude
value. Similarly, the difference between the negative speed
amplitude 84 and the target rotation speed, expressed as an
absolute value, may be a second amplitude value. The average
frequency of the ripples may be determined by counting the number
of positive/negative peaks for a given time period or by taking the
speed of the wave and dividing by its wavelength. The motor speed
and motor current waveforms have a quasi sinusoidal waveform for
which a frequency may be determined using the positive/negative
peaks for the time of the plateau 74b, 76b.
[0050] The motor current waveform in a fairly well distributed load
shows a similar waveform to the motor speed with the current
tending to lead the speed. The leading of the current relative to
the motor speed results from the controller attempting to maintain
the motor speed at the set speed. Because the magnitude of the
current depends on the controller trying to maintain the set speed,
the motor current does not have a corresponding set point in the
way that the motor speed has a set point.
[0051] The amplitude values and frequency values for either or both
of the motor speed and motor current may be stored by the machine
controller 32 as individual data values as well as a cumulative
value. The amplitude values may be averaged and, more preferably, a
running average of the amplitude values may be determined and
stored by the machine controller 32. The frequency values may also
be averaged and, more preferably, a moving average of the frequency
values may be determined and stored by the machine controller 32.
The averages may be calculated over a set or variable time or a set
or variable amount of movement of the clothes mover. The averages
may be temporary averages or cumulative averages.
[0052] FIG. 10 shows an example of the current and speed waveforms
that are indicative of bunching. Looking more closely at the
ripples of the motor current waveform of FIG. 10, the forward
stroke 74 has four positive peak points 92a-d while the backward
stroke 76 has eight positive peak points 95a-h. It has been
determined that the inconsistency between the number of peaks
indicates bunching exists. This is because in the forward stroke
the load is pushed in a forward or clockwise motion by the clothes
mover 20. However, when the clothes mover 20 is in the backward
stroke the bunched clothing may not be effectively pushed by the
backward stroke. Instead, the clothes mover 20 skips underneath the
bunched fabric items 3 and the bunched fabric items 3 do not
immediately follow the clothes mover and may continue in the
forward direction. This asymmetry in the clothes and basket motion
manifests as asymmetry in the motor current waveforms between the
forward and backward strokes.
[0053] More specifically, it is believed that the increased
frequency of the backward stroke may be caused because the bunched
fabric items are not traveling with the clothes mover to the same
extent as on the forward stroke, resulting in a greater number of
separations and contacts between the bunched clothes and the blades
of the clothes mover, which correspondingly loads/unloads the
clothes mover at a greater frequency, causing the motor to respond
by increasing/decreasing current/speed in an attempt to maintain
the set speed. In this way, the clothes mover can be thought of as
skipping beneath the bunched fabric items, with the skipping
resulting in an increased number of peaks in the backward stroke of
the motor current and motor speed waveforms as well as a reduction
in the magnitude of the peaks.
[0054] While the increased frequency in the backward stroke
relative to the forward stroke indicates bunching, it has been
determined that the frequency information can be used to quantify
the degree of bunching in addition to the existence of bunching.
The degree of bunching of the fabric items may be determined from
the motor current data in real-time. In this way, the use of the
data amounts to a real-time sensor placed in the wash chamber for
determining the degree of bunching. Such a sensor has never before
been available.
[0055] Applicants have also determined that the amplitude of the
motor current may provide an accurate estimate of the degree of
bunching of the fabric items, thereby enabling corrective action to
be taken. The degree of bunching of the fabric items in a laundry
load may be determined from the sample data of the waveforms of the
forward and backward strokes, more specifically by comparing the
determined amplitudes of the forward and backward strokes. For
example, the sample data may be compared essentially on a point by
point basis between corresponding points for the forward and
backward strokes. The corresponding points may be thought of as
paired points. The comparison may be done by determining the
difference in amplitude between the corresponding paired points for
the forward and backward strokes. This difference may be determined
for all of the paired points or some of the paired points. The
difference may be determined over one or multiple oscillation
cycles. The difference may be tracked as a single difference, a
running total that may be weighted or not, or as a trapped maximum
difference. The difference of the amplitude may then be compared to
a predetermined threshold and the degree of bunching may then be
determined. The predetermined threshold may be a range of values or
a single value. In most cases, it will be a single value that
represents the threshold between acceptable and unacceptable
bunching for the given washer.
[0056] Applicants have also determined that one type of difference
which may accurately determine the degree of bunching is the
asymmetry between the forward and backward strokes of the motor
current waveform. This asymmetry can be computed from sample data
of the waveforms from both the forward and backward strokes. This
can be done using the entire waveform for the stroke or a part of
the waveform. The asymmetry may be tracked as a single value, a
running total that may be weighted or not, or as a trapped maximum
value. The asymmetry can provide an estimate of the degree of
bunching of the fabric items, thereby enabling corrective action to
be taken. The more asymmetrical the waveforms are the greater the
degree of bunching estimated.
[0057] A more detailed look at one implementation of determining
the difference using the paired points should be helpful in further
understanding the invention. It should be noted that the following
implementation has been based on a mean squared difference method,
which has been found to provide the desired resolution for
determining the degree of bunching for the contemplated washer;
however, it may be contemplated that other mathematical methods may
also be used.
[0058] Looking to FIG. 10 as an example, the sample data of the
clothes mover motor current for the forward stroke at the
twenty-fifth sample is depicted as A. The sample data of the
clothes mover motor current for the backward stroke at the
twenty-fifth sample is depicted as B. Points A and B represent a
set of paired points in the motor current waveform as each
corresponds to the twenty-fifth sample during its respective
stroke. In this manner the magnitude of each point on the forward
stroke of the waveform may be compared to its counterpart on the
backward stroke. In FIG. 10 the sampling rate results in there
being fifty sets of paired points. The mean square difference may
be taken between such paired points.
MSD.sub.--I=1/N.SIGMA..sub.n=1.sup.n=N{I(CW,n)-I(CCW,n)}.sup.2
(1)
where:
[0059] I is the current signal;
[0060] MSD_I is the mean squared difference for the current
signal;
[0061] CW is a clockwise stroke of the clothes mover;
[0062] CCW is the counterclockwise stroke of the clothes mover;
[0063] "N" is the total number of paired data points; and
[0064] "n" is the paired data points of interest in the total
number N of paired data points.
[0065] The number of paired points N may be across one complete
oscillation cycle. Alternatively it may be across more than one
cycle or less than one cycle. The MSD_I value may then be compared
to a threshold T to determine the degree of bunching. The formulas
below represent the comparison made between MSD_I and the threshold
value.
MSD.sub.--I>=T=Clothes are bunched (2)
MSD.sub.--I<T=Clothes are not bunched (3)
[0066] The threshold value T will typically be empirically
determined for different clothes washers, and established based
upon factors such as fabric type, laundry load size, laundering
cycle, clothes mover configuration, motor type, transmission type,
and the like. An MSD_I greater than or equal to the threshold value
T indicates the clothes are bunched. An MSD_I less than the
threshold value T indicates the clothes are not bunched.
[0067] Another implementation takes the average of the mean squared
difference determined by formula (1) for a number of mean squared
difference determinations, which may be represented by the
formula:
MSD.sub.--IA=1/M.SIGMA..sub.m=1.sup.m=MMSD.sub.--I(m) (4)
where:
[0068] M represents the number of mean squared difference
determinations used to compute the average; and
[0069] m is the current mean squared difference determination.
[0070] It is currently contemplated that M will represent the
number of oscillation cycles and the mean squared difference MSD_I
will be calculated for paired points corresponding to a complete
oscillation cycle. In that way, the MSD_IA will be an average of
the mean squared difference for multiple oscillation cycles.
However, as the MSD_I determination need not be on an oscillation
cycle bases, the MSD_IA also need not be on an oscillation cycle
basis.
[0071] This MSD_IA value may then be compared to its own threshold
TA to determine the degree of bunching. The formulas below
represent the comparison made between MSD IA and the threshold
value.
MSD.sub.--IA>=TA=Clothes are bunched (5)
MSD.sub.--IA<TA=Clothes are not bunched (6)
[0072] An MSD_IA greater than or equal to the threshold value TA
indicates the clothes are bunched. An MSD_IA less than the
threshold value TA indicates the clothes are not bunched.
[0073] The methods represented by formulas (1) and (4) may also be
implemented as a moving average over a predetermined set of values,
sets of paired points or mean squared difference determinations as
the case may be. For example, a moving average using formula (1)
could be continuously calculated using the most recent specified
number of paired points such as the most recent 5 points, 50
points, 500 points, or whatever number is chosen. The number of
paired points would likely be based on the number of paired points
required by a particular washing machine platform to provide the
degree of bunching at a resolution needed for the operation of the
particular washing machine platform. For formula (4), a moving
average calculation could also be implemented by picking a
predetermined number and sequence of the mean squared difference
determinations from formula (1) such as the last 5, 10, or 15 mean
squared difference determination. The number of mean squared
difference determinations will likely be based on the number
required by a particular washing machine platform to provide the
degree of bunching at a resolution needed for the operation of the
particular washing machine platform.
[0074] An illustrative example of the use of the bunch detection
during the operation of the washing machine should be helpful in
understanding the bunch detection within the washing operation.
During a fill step in a wash cycle, the clothes mover 20 may be
rotated through a pre-selected number of preliminary oscillation
cycles, for example five, while water is added to the wash chamber,
or after an initial filling of the clothes washer 10. Thus, the
clothes mover 20 rotates through five forward strokes and five
backward strokes while the machine controller 32 keeps track of the
degree of bunching using the previously described method. This may
be accomplished by the machine controller receiving data samples of
the motor current from the sensor 31, storing the values of the
magnitude at the same specific sampling time for each of the
forward and backward strokes in the oscillation cycle, determining
the mean square difference between the two points and maintaining
an average of the mean squared differences. At the end of one
cycle, the mean squared difference average, MSD_I, may be compared
to a pre-selected threshold value, T. Alternatively or
additionally, a comparison may also be made at the end of multiple
cycles, where the value may be either a moving average or not. The
machine controller 32 uses the determination of the degree of
bunching to control the operation of the clothes washer.
Specifically the machine controller 32 will take corrective action
to separate the bunched clothing if the mean squared difference
equals or exceeds than the threshold.
[0075] It should be noted that other types of threshold comparisons
may exist. As described, the mean squared difference determined
value is compared on a greater than or equal to basis. However, the
threshold could be picked in such a way that the comparison may be
done on a greater than basis, less than basis, or less than or
equal to basis. The type of comparator may normally be controlled
by how the threshold number is quantified. The predetermined
threshold value may represent an optimal uniform distribution level
reflecting an optimal combination of cleaning effort and cleaning
efficiency. An optimal level has been reached when the mean squared
difference or average of mean squared difference reaches the
pre-selected threshold value.
[0076] Another way in which the current and motor speed information
can be used to determine the degree of bunching is by using the
ripple frequency of the current and motor speed waveforms. One
manner of using the frequency is to use an average frequency, which
may include determining the average frequency for each of the
forward and backward strokes and then comparing the determined
average frequencies of the forward and backward strokes. For
example, the average frequency may be compared between
corresponding samples for the forward and backward strokes. The
corresponding samples may be thought of as paired sections of each
stroke. The comparison may be done by determining the difference in
the average ripple frequency between the forward and backward
strokes. This difference may be determined for any useful time
segment or operation segment, such as: multiple oscillation cycles,
all of an oscillation cycle, or a portion of an oscillation cycle.
The difference may be tracked as a single difference, a running
total that may be weighted or not, or as a trapped maximum
difference. The difference of the frequencies may then be compared
to a predetermined threshold and the degree of bunching may then be
determined. The predetermined threshold may be a range of values or
a single value. In most cases, it will be a single value that
represents the threshold between acceptable and unacceptable
bunching for the given washer.
[0077] A more detailed look at an implementation of determining the
difference using frequency data should be helpful in further
understanding the invention. It should be noted that the following
implementation has been based on an average ripple frequency
difference method, which has been found to provide the desired
resolution for determining the degree of bunching for the
contemplated washer; however, it may be contemplated that other
mathematical methods may also be used.
[0078] Using the data of FIG. 10 for the example, the frequency
data of the clothes mover motor speed for the forward stroke is
depicted as 74. Motor current may also be used to determine the
degree of bunching but this explanation will use only motor speed.
The frequency data of the clothes mover motor speed for the
backward stroke is depicted as 76. The larger wavelengths in the
forward stroke 74 correlates to the forward stroke 74 having a
smaller frequency then the backward stroke 76 which has a much
larger frequency and much shorter wavelengths. In this manner the
average frequency for those samples may be determined from the
waveform and may be compared to its counterpart on the forward or
backward stroke.
[0079] Using the data of FIG. 10 for the example, the average may
be calculated on a per stroke basis and then compared by taking the
difference between the average frequencies for forward and backward
stroke. In FIG. 10, the sampling rate was approximately fifty data
points per stroke, resulting in fifty pairs of corresponding data
points for the forward and backward strokes. The difference in the
average frequency difference may be taken between such paired
values using the formula:
delta.sub.--F={Avg.sub.--F(W(CW, n))-Avg.sub.--F(W(CCW, n)} (1)
where:
[0080] W is either the speed or current signal;
[0081] Delta_F is the difference between the average frequencies of
the signal;
[0082] CW is a clockwise stroke of the clothes mover;
[0083] CCW is the counterclockwise stroke of the clothes mover;
[0084] "n" is the number of samples used to determine the average
frequency in each of the clockwise and counterclockwise strokes;
and
[0085] Avg_F is the average frequency of one of the forward or
backward strokes for the "n" samples taken.
[0086] The delta_F value may then be compared to a threshold T to
determine the degree of bunching. The formulas below represent the
comparison made between delta_F and the threshold value.
delta.sub.--F>=T=Clothes are bunched (2)
delta.sub.--F<T=Clothes are not bunched (3)
[0087] The threshold value T will typically be empirically
determined for different clothes washers, and established based
upon factors such as fabric type, laundry load size, laundering
cycle, clothes mover configuration, motor type, transmission type,
and the like. A delta_F greater than or equal to the threshold
value T indicates the clothes are bunched. A delta_F less than the
threshold value T indicates the clothes are not bunched.
[0088] Another implementation takes the average of the frequency
difference determined by formula (1) for a number of frequency
difference determinations, which may be represented by the
formula:
delta.sub.--FA=1/M.SIGMA..sub.m=1.sup.m=Mdelta.sub.--F(m) (4)
where:
[0089] M represents the number of frequency difference
determinations used to compute the average; and
[0090] m is the speed or current frequency difference
determination.
[0091] It is currently contemplated that M will represent the
number of oscillation cycles and the frequency difference delta_F
will be calculated for a sample corresponding to a complete
oscillation cycle. In that way, the delta_FA will be an average of
the frequency difference for multiple oscillation cycles. However,
as the delta_F determination need not be on an oscillation cycle
bases, the delta_FA also need not be on an oscillation cycle
basis.
[0092] This delta_FA value may then be compared to its own
threshold TA to determine the degree of bunching. The formulas
below represent the comparison made between delta_FA and the
threshold value.
delta.sub.--FA>=TA=Clothes are bunched (5)
delta.sub.--FA<TA=Clothes are not bunched (6)
A delta_FA greater than or equal to the threshold value TA
indicates the clothes are bunched. A delta_FA less than the
threshold value TA indicates the clothes are not bunched.
[0093] This implementation has two tunable parameters including M
which represents the number of frequency difference determinations
used to compute the average and may be varied to include a larger
or smaller number of determinations. A larger amount of
determinations would show the bunching over a greater period of
time while a smaller number would be an average for a shorter time
period. Furthermore, TA the threshold level may be tuned to allow
bunching to be determined be the invention at lower or greater
amounts.
[0094] By tuning these parameters the best performance can be
extorted using this algorithm. The tunable parameter values may
also differ between the speed based and current based algorithms.
But irrespective of the signal used, the underlying algorithm
metric and concept are the same. The main reason for choosing a
moving average as a way to filter the data is to minimize embedded
software implementation costs (i.e. memory/CPU usage); otherwise, a
more expensive filter may be used to improve detection
accuracy.
[0095] The methods represented by formulas (1) and (4) may also be
implemented as a moving average over a predetermined set of
samples, either parts of an oscillation cycle or multiple
oscillation cycles as the case may be. For example, a moving
average using formula (1) could be continuously calculated using
the most recent specified number of samples for each of the forward
and backward strokes such as the most recent 5 samples, 50 samples,
500 samples, or whatever number is chosen, of each of the forward
and backward strokes. The number of samples would likely be based
on the number of samples required by a particular washing machine
platform to provide the degree of bunching at a resolution needed
for the operation of the particular washing machine platform. For
formula (4), a moving average calculation could also be implemented
by picking a predetermined number and sequence of the frequency
difference determinations from formula (1), such as the last 5, 10,
or 15 frequency difference determinations. The number of frequency
difference determinations will likely be based on the number
required by a particular washing machine platform to provide the
degree of bunching at a resolution needed for the operation of the
particular washing machine platform.
[0096] An illustrative example of the use of the bunch detection
during the operation of the washing machine should be helpful in
understanding the bunch detection within the washing operation.
During a fill step in a wash cycle, the clothes mover 20 may be
rotated through a pre-selected number of preliminary oscillation
cycles, for example five, while an addition of water to the wash
chamber takes place, or after an initial filling of the clothes
washer 10. Thus, the clothes mover 20 rotates through five forward
strokes and five backward strokes while the machine controller 32
keeps track of the degree of bunching using the previously
described method. This may be accomplished by the machine
controller receiving data samples of the motor speed or motor
current from the sensor 31, storing the values of the average
frequency for each of the forward and backward strokes in the
oscillation cycle, determining the difference between the two
average frequencies and maintaining the differences of the average
frequencies. At the end of one cycle, the frequency difference,
delta_F, may be compared to a pre-selected threshold value, T.
Alternatively or additionally, a comparison may also be made at the
end of multiple cycles, where the value may be either a moving
average or not. The machine controller 32 uses the determination of
the degree of bunching to control the operation of the clothes
washer. Specifically the machine controller 32 will take corrective
action to separate the bunched clothing if the frequency difference
equals or exceeds than the threshold.
[0097] It should be noted that other types of threshold comparisons
may exist. As described, the frequency difference determined value
may be compared on a greater than or equal to basis. However, the
threshold could be picked in such a way that the comparison may be
done on a greater than basis, less than basis, or less than or
equal to basis. The type of comparator may normally be controlled
by how the threshold number may be quantified. The predetermined
threshold value may represent an optimal uniform distribution level
reflecting an optimal combination of cleaning effort and cleaning
efficiency. An optimal level has been reached when the difference
between the average frequencies or average of the difference
between the average frequencies reaches the pre-selected threshold
value.
[0098] The ability to determine or sense the degree of bunching
benefits the improvement of the wash performance as actions may be
taken to reduce the bunching. Once one has the ability to determine
the degree of bunching, one may then manipulate the wash cycle
accordingly to control the degree of bunching. Controlling the
liquid level in the clothes washer constitutes one way in which the
degree of bunching may be controlled. As the liquid level increases
in the wash chamber the fabric items may become more submerged.
Even if the articles are not fully submerged the additional liquid
adds to the buoyancy effect of the fabric items. This has an
opposite effect than the weight force of the fabric items. In some
instances, the liquid may be sufficiently deep and the clothes
mover may sufficiently agitate the liquid that some or all of the
fabric items become unbunched which will greatly reduce the loading
of the clothes mover 20 by the fabric items. This in turn allows
the clothes mover to move freely and increase its speed in
comparison to when the fabric items were bunched. This allows the
controller to reduce the motor current. Thus, the determined degree
of bunching may be used to adjust the liquid level and thereby
control the degree of bunching.
[0099] Another way of controlling the degree of bunching
constitutes changing the length and speed of the forward or
backward stroke of the clothes mover in the clothes washer. First,
the speed of the cloth mover may be controlled. Additionally, the
clothes mover may be controlled to increase or decrease the length
of the forward or backward stroke. Shorter faster strokes of the
cloth mover may more easily break up the bunched fabric articles.
Once the fabric articles are more separated they may then continue
to be more uniformly dispersed in the wash chamber by the forward
and backward strokes of the cloth mover. Shorter strokes may also
be used in combination with increased liquid levels in the wash
chamber to reduce the amount of bunching of the fabric articles.
Thus, the determined degree of bunching may be used to adjust the
length and speed of the cloth mover stroke and thereby control the
degree of bunching.
[0100] Furthermore, the machine may also be stopped if the degree
of bunching happens to be high enough for safety reasons and so
damage will not be done to the machine. Moreover, if the mean
squared difference value or the moving average mean squared
difference value become less than the threshold the current
addition of liquid to the wash chamber will be stopped. Or if the
mean squared difference value or the moving average mean squared
difference value becomes less than the threshold the strokes may be
lengthened and slowed as necessary.
[0101] The liquid level and stroke length and speed adjustments may
be conducted at any time during the wash cycle. For example, it may
be part of the filling step or it may be part of the wash or rinse
steps. In this way, the fabric items may be unbunched as soon as
bunch detection occurs. This also acts as a safety step if fabric
items are irreparably bunched immediately upon a user loading the
clothing into the washing machine. The machine may be immediately
stopped before damage occurs to the machine.
[0102] The invention described herein provides an optimized
laundering cycle by setting a liquid level, stroke length and
stroke speed that are sufficient for satisfactorily cleaning a
laundry load, thereby reducing the bunching of fabric items in the
load. Thus, the items being laundered are cleaned more efficiently
and cleaned better thereby saving the consumer costs related to
cleaning and recleaning. Finally, the utilization of motor current
in determining an optimal liquid level and stroke length and speed
requires no additional instrumentation, thereby minimizing
additional cost. The invention simply utilizes readily available
information in a new manner to control an operation in order to
optimize the laundering performance of a clothes washer.
[0103] While the invention has been specifically described in
connection with certain specific embodiments thereof, understand
that this constitutes an illustration and not a limitation.
Reasonable variation and modification are possible within the scope
of the forgoing disclosure and drawings without departing from the
spirit of the invention defined in the appended claims.
* * * * *