Note: Descriptions are shown in the official language in which they were submitted.
CA 02484406 2004-10-08
TITLE: METHOD AND APPARATUS FOR SPINNING FABRICS
BACKGROUND OF THE INDENTION
S The present invention relates to the method and apparatus for spinning
fabrics.
Presently existing horizontal axis washing machines include a stationary tub
which
is mounted within a cabinet structure. Extending between the tub and an access
opening
within the cabinet is a flexible boot seal which is attached to both the
cabinet and the
stationary tub. Within the stationary tub is a washing basket that is mounted
for rotation.
The washing basket includes holes therein for permitting washing fluid to pass
from the
washing basket in an outward radial direction into the tub which surrounds it.
The rotational axis of the washing basket is at an angle slightly elevated
above
horizontal. This results in the washing fluid within the basket residing in
the lower rear
portion of the washing basket. The washing basket includes a rim surrounding
an access
opening which is positioned closely adjacent to the flexible boot seal.
During the washing cycle the washing basket reciprocates back and forth in a
rotational direction, and the clothing is tumbled within the washing basket to
become
washed by the fluid.
After the washing cycle is complete the washing fluid is drained from the
washing
basket and the washing basket begins a spin cycle wherein the washing basket
rotates at a
spin speed on the order of 1000 rpm. During the spin cycle, centrifugal force
causes the
fabrics within the washing basket to be pressed in an outward radial direction
against the
walls of the washing basket. This phenomenon is sometimes referred to as
plastering. The
rotation of the washing basket causes the washing fluid to pass through the
plastered
fabrics and outwardly through the holes in the walls of the washing basket.
On occasion some of the fabrics extend outwardly beyond the outer rim of the
washing basket and fractionally engage the boot seal. If these fabrics are
permitted to stay
in this position during the spin cycle they will create friction against the
stationary flexible
boot seal and ultimately cause damage to the boot seal.
Therefore a primary object of the present invention is the provision of an
improved
method and apparatus for spinning fabrics.
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A further object of the present invention is the provision of an improved
method
and apparatus for spinning fabrics which, when the fabrics engage the boot
seal, detects
engagement and terminates the spinning cycle.
A further object of the present invention is the provision of an improved
method
wherein the washing fluid is not drained while the washing basket rotates
before the spin
cycle, the washing fluid contributing to the redistribution of the fabrics
within the basket.
A further object of the present invention is the provision of a method and
apparatus
for spinning fabrics which is economical, durable in use, and efficient in
operation.
BRIEF SUMMARY OF THE INVENTION
The foregoing objects may be achieved by a method for operating a washing
machine having a washing basket mounted for rotation within a stationary tub.
The
washing basket includes an open rim and a basket wall containing a plurality
of holes
therein. A quantity of washing fluid is within the washing basket and one or
more fabrics
are also within the washing basket. A flexible stationary boot seal is
positioned closely
adjacent the rim of the washing basket.
The method comprises rotating the washing basket within a stationary tub
relative
to the boot seal at a first rotational speed insufficient to plaster the
fabrics against the
basket wall in response to centrifugal force. The rotational speed of the
washing basket is
gradually increased to a second rotational speed which is sufficient to cause
the fabrics to
be plastered against the basket walls in response to centrifugal force. The
rotational speed
of the washing basket is increased further to a third rotational speed higher
than the second
rotational speed, and then is reduced back to the second rotational speed. The
washing
fluid is then drained from the washing basket and a spin cycle is begun.
During the spin
cycle the basket is rotated at a fourth rotational speed greater than the
first, second and
third rotational speeds and sufficient to cause washing fluid to be extracted
from the fabrics
and to move outwardly through the holes in the washing basket walls in
response to
centrifugal force.
A further feature of the present invention is the step of checking for an
imbalance
condition of the fabrics within the basket while the basket is rotating at the
second
rotational speed after the draining step.
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According to a further feature of the present invention the rotation of the
basket is
stopped when an imbalance condition is sensed. The rotational speed is then
returned to
the second rotational speed.
According to another feature of the present invention the step of checking for
an
imbalance condition comprises sensing whether or not there is a torque change
or a
rotational speed change of the basket while rotating at the third rotational
speed.
According to a further feature of the present invention the first rotational
speed is
approximately 50 rpm.
According to another feature of the present invention the second rotational
speed is
approximately 85 rpm.
According to another feature of the present invention the third rotational
speed is
approximately 100 rpm.
According to another feature of the present invention the basket is rotated at
a
tumble speed insufficient to cause the fabrics to become plastered against the
basket wall in
response to centrifugal force but instead to tumble within the basket during
rotation. The
washing fluid is maintained within the washing basket. The rotational speed of
the basket
is increased to a plaster speed sufficient to cause the fabrics to become
plastered against the
basket wall in response to centrifugal force. The washing fluid is then
drained from the
washing basket. A sensor senses whether or not the fabrics create an imbalance
condition
during the rotation of the basket at the plaster speed. The plaster speed is
then reduced for
a predetermined time interval to the tumble speed in response to sensing an
imbalance
condition during the rotation of the basket at the plaster speed. This causes
the fabrics to
cease being plastered against the basket wall and instead causes them to
tumble within and
be redistributed within the washing basket. The plaster speed is then resumed
after the
predetermined time interval and the rotational speed is then increased to a
spin speed
sufficient to cause the washing fluid within the fabrics to be extracted and
pass out of the
washing basket through the holes in the wall of the washing basket.
According to another feature of the present invention during the spin cycle a
sensor
senses for increased torque or reduced rotational speed of the washing basket.
In response
to sensing increased torque or reduced rotational speed, the washing basket is
slowed to a
tumble speed insufficient to cause the fabrics to become plastered against the
wall of the
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washing basket in response to centrifugal force but instead to cause the
fabrics to tumble
and be redistributed in the washing basket. The washing basket is then
returned to the spin
speed.
The apparatus of the present invention comprises a stationary outer tub, an
inner
washing basket having a basket wall, holes within the basket wall and an
annular basket
rim defining an open end to the washing basket. The inner washing basket is
mounted for
rotation within the stationary outer tub. A wasMng fluid is within the washing
basket and a
boot seal is attached to the outer tub. The boot seal is positioned closely
adjacent the
annular rim of the washing basket. A motor is adapted to rotate the washing
basket at a
tumble speed wherein the fabrics within the washing basket are tumbled but do
not become
plastered against the washing basket wall, at a plaster speed wherein the
fabrics within the
washing baskets are plastered against the washing basket walls, and at a spin
speed wherein
the washing fluid within the fabrics is extracted from the fabrics and exits
the holes in the
washing basket in response to centrifugal force. A sensor senses the
combination of high
1 S torque of the washing basket and the lower than desired rotational speed
of the washing
basket caused by fabrics frictionally engaging the boot seal while the washing
basket is
spinning at the spin speed. A controller connected to the sensor and the motor
causes the
motor to terminate the spinning of the washing basket.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a washing machine of the present invention.
Figure 2 is a schematic view showing the washing basket, the tub, the flexible
boot
seal and a portion of the cabinet, together with block diagrams showing
various
components in the system.
Figure 3 is a flow diagram showing the steps in the method of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, the numeral 10 generally designates a washing
machine
made according to the present invention. Washing machine 10 includes a cabinet
12
having a front door 14. The front door 14 includes a nose 16 which projects
inwardly
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when the door is closed. The door is hinged to close over an access opening 18
having a
boot seal 20 surrounding the access opening 18.
A detergent dispenser 22 is provided in the top of the washing machine 10 for
introducing detergents and the like to the interior of the washing machine 10.
Washing
machine 10 also includes a control panel 24 having selector buttons 26, 28,
30, and 32.
The control panel 24 also includes a control knob 34.
Mounted for rotation within the cabinet 12 is a wash basket 36 having holes 38
in
its peripheral wall. Wash basket 36 also includes a plurality of fins or
blades 40 protruding
inwardly from its peripheral wall for tumbling the fabrics within the washing
basket 36
during the time that the washing basket 36 is rotating.
Surrounding the washing basket 36 is a stationary tub 42 (Figure 2) which is
mounted within the cabinet 12. The stationary tub 42 includes an open upper
end 43 to
which is attached the boot seal 20. Boot seal 20 includes an inner end 46
which is attached
to the open upper end 43 of tub 42. Also boot seal 20 includes an outer end 48
attached to
cabinet 12 and a fold 50 between inner end 46 and outer end 48.
Washing basket 36 includes an annular rim 52 which is positioned adjacent the
open upper end 43 of the tub 42. This annular rim 52 forms a basket opening
54. Within
basket 36 is a washing fluid 56 which contains a plurality of fabrics 58.
A motor 60 is connected to the transmission 62 for rotating the washing basket
36.
A speed sensor or tachometer 64 is connected to the motor 60 for sensing the
rotational
speed at which motor 60 is operating. Speed sensor 64 is also connected to a
controller 66.
The controller 66 is also connected to a drive controller 67 which in turn is
connected to
motor 60. A drive torque sensor 65 senses the torque on motor 60 and provides
feedback
from the drive controller 67 to the controller 66. The purpose of drive torque
sensor 65 and
speed sensor 64 is to detect an unbalance condition or frictional engagement
of fabrics on
boot seal 20 in the manner described below as to Figure 3.
A drain pump 68 is connected by conduit to the lower most region of tub 42 for
draining washing fluid 56 out of the washing basket 36 and the tub 42. The
fluid 56
communicates from within the washing basket 36 to the tub 42 through the holes
38
(Figure 1 ). A drain sensox 70 of the pressure sensitive type commonly used in
washing
machines is designated by the numeral 70 and is connected to the drain conduit
leading to
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the drain pump 68. All of the drive controller 67, the torque sensor 65, speed
sensor 64,
the drain pump 68, and the drain sensor 70 are connected to the controller 66.
Refernng now to Figure 3, a flow diagram shows the transition from the washing
cycle through the spin cycle. To begin the transition the washing basket is
rotated in one
direction at a tumble speed or first speed of approximately 50 rpm. The
rotational speed
may vary without detracting from the invention, but the rotational speed
should be a
"tumble speed". The term "tumble speed'" refers to a rotational speed which
causes the
fabrics to tumble within the washing basket 36 without being plastered against
the side
walls of the washing basket 36 by centrifugal force.
In preparing for the spin cycle the rotational speed is increased from 50 rpm
to
approximately 85 rpm as designated by the box numbered 72. At 85 rpm the
fabrics are
plastered to the wall of the washing basket 36. Thus the rotational speed is
increased from
the tumble speed or first speed to a plaster speed or second speed sufficient
to plaster the
fabrics against the walls of the washing basket 36. It is to be noted that the
washing fluid
56 remains in the basket during this step.
The box 74 reflects the next step of the process. The washing fluid still
remains in
the washing basket 36, and the rotational speed is increased to a higher
plaster speed or a
third speed of approximately 100 rpm. This higher plaster speed is maintained
for
approximately 30 seconds. The speed of the higher plaster speed and the time
period for
maintaining this higher plaster speed may vary without detracting from the
invention.
Next, the drain pump 68 is turned on to drain the washing fluid 56 from the
washing basket 36 and the outer tub 42. The rotational speed of the washing
basket 36 is
reduced to the lower plaster speed or second speed which is approximately 85
rpm. The
turning on of the drain pump 68 is designated by box 76 and the reduction in
speed to 85
rpm is designated by the box 78.
Throughout this process the controller 66 controls the operation of the motor
60,
the drive controller 67 and the drain pump 68.
The box 84 shows a testing of the drain time. If the drain time equals or
exceeds 60
seconds the process moves on to box 80. The box 80 reflects a sensing
operation that is
conducted by drain sensor 70 to determine whether or not the drain is
complete. If the
drain sensor senses that the drain is not complete, the drain time is extended
as reflected by
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box 82. Box 84 reflects a determination of whether or not the drain time
equals or exceeds
four minutes. If it does, the controller 66 shuts the machine down as
reflected in box 110.
Otherwise the draining continues until complete and the controller 66 moves to
the next
step of the process.
This next step is reflected by box 86 and involves checking whether or not the
basket is in an unbalanced condition. Such unbalanced conditions occur when
fabrics
within the washing basket 36 are unevenly distributed within the washing
basket 36. It
should be noted that the rotational speed of the washing basket remains at
approximately
85 rpm or at the first plaster speed.
The controller 66 detects an unbalance condition through both the drive torque
sensor 65 and the speed sensor 64. Controller 66 sends an electrical signal to
the drive
controller 67 which responds by driving motor 60 at the desired speed which is
85 rpm.
The drive torque sensor senses the current necessary to keep motor 60
operating at the 85
rpm, and feeds this information back to the controller 66. The current needed
to drive
1 S motor 60 is related to the torque on motor 60. If an unbalance condition
occurs the basket
exhibits a high torque while lifting the unbalanced load and a reduced torque
when the load
drops. The drive torque sensor 65 senses this fluctuation in the
current/torque and feeds
that information back to the controller. In addition, the speed sensor 64
detects fluctuations
in speed of the rotation of motor 60.
If the torque or speed sensor 64 senses an unbalanced condition, the
controller 66
stops the rotation of the washing basket as reflected by the box 88. After the
rotation has
been stopped it is again increased to the tumble speed of SO rpm as designated
by the
numeral 90. The rotational speed is then gradually increased to 85 rpm as
indicated by box
91. The box 92 reflects the addition of a number to a counter. The box 94
reflects
checking for the counter to determine whether ar not the counter has exceeded
a
predetermined number indicated as "X". This feature prevents the washing
machine from
continuing indefinitely in this cycle if the imbalance condition persists. If
the number in
the counter exceeds "X" the machine is shut down as shown by box 96. Otherwise
the
method continues back to box 86.
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In most situations the stopping of the rotation and the renewed increasing of
the
rotation to the first plaster speed will cause the fabrics to redistribute
within the basket 36
and will eliminate the unbalance condition.
If no unbalance condition is sensed, or if it is corrected by the process
described
above, the controller causes the washing basket to move into the high spin
speed process as
indicated at box 98. During the spinning operation, the spin speed or fourth
speed of the
washing basket is sufficient to cause the fabrics not only to be plastered
against the walls of
basket 36 but also causes the extraction of the liquid from the fabrics
through holes in
washing basket 36. The preferred ultimate or maximum spin speed for the
washing basket
36 is approximately 1000 rpm, but this may be varied without detracting from
the
invention. During the spinning process the washing basket 36 may be rotated at
numerous
spin speeds for periods of time.
During the spin cycle, even though there may not be an unbalance condition, it
is
possible that the fabrics 58 may extend outwardly beyond the rim 52 of the
washing basket
36 and may engage the boot seal 20. High speed rotation of the washing basket
36 causes
these fabrics to wear against the boot seal 20 and thus cause damage to the
boot seal 20.
This condition is shown schematically in Figure 2 by the fabric 58 which
contacts the boot
seal 20.
If fabrics 58 frictionally engage boot seal 20 then speed sensor 64 detects a
reduction (box 100) in rotational velocity of washing basket 36 and torque
sensor 65 senses
(box 102) an increase in torque caused by the friction. Drive torque sensor 65
senses
whether or not the torque has increased above a threshold level as represented
by box 104.
Then the controller determines if the time of increased torque above the
threshold has
existed for more than thirty seconds (box 106). If so the machine shuts down
as indicated
by box 108, but if not the high speed spin continues. If there is no
frictional engagement
between the boot seal 20 and the fabrics 58, the spin cycle continues until it
is over as
indicated at box 110, and the machine shuts down as shown in box I 12. Testing
of the
completion of the spin cycle is usually done by a timer which times the length
of the spin
cycle.
While the rotational speeds of 50 rpm, 85 rpm, 100 rpm, and 1000 rpm are the
preferred rotational speeds for the tumble speed or first speed, the lower
plaster speed or
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second speed, the higher plaster speed or third speed, and the spin speed or
fourth speed,
these various rotational speeds may be varied without detracting from the
invention. The
tumble speed refers to a speed which causes rotation of the basket 36 but
causes the fabrics
to tumble rather than to plaster against the walls of the washing basket 36.
The lower and
higher plaster speeds refer to rotational speeds which cause the fabrics to be
plastered
against the walls of the washing basket 36. The spin speed refers to a
rotational speed
sufficient to cause not only the plastering of the fabrics against the walls
of the washing
basket 36, but also to cause the washing fluid to be extracted outwardly from
the fabrics
through the holes in the washing basket 36 and through the drain provided by
drain pump
68. The desired maximum spin speed is 1000 rpm. However, the testing for the
fabrics 58
rubbing the boot seal 20 designated by boxes 100, 102 and 104, occurs at
approximately
675-800 rpm.
In the drawings and specification there has been set forth a preferred
embodiment
of the invention, and although specific terms are employed, these are used in
a generic and
descriptive sense only and not for purposes of limitation. Changes in the form
and the
proportion of parts as well as in the substitution of equivalents are
contemplated as
circumstance may suggest or render expedient without departing from the spirit
or scope of
the invention as further defined in the following claims.
