U.S. patent application number 12/992931 was filed with the patent office on 2011-08-04 for spray rinsing method intended for washing machines.
This patent application is currently assigned to GIRBAU, S.A.. Invention is credited to Ramon Sans Rovira.
Application Number | 20110185515 12/992931 |
Document ID | / |
Family ID | 41318383 |
Filed Date | 2011-08-04 |
United States Patent
Application |
20110185515 |
Kind Code |
A1 |
Sans Rovira; Ramon |
August 4, 2011 |
SPRAY RINSING METHOD INTENDED FOR WASHING MACHINES
Abstract
The machine has a drum with a perforated wall capable of
receiving a load of clothes, a motor for rotating the drum at
variable speeds, and a spraying device capable of introducing
liquid into the drum. The method includes performing an
impregnation with an amount of liquid by several spraying steps for
spraying the liquid on the load of clothes while the drum rotates
at a medium rotational speed sufficient to keep the load of clothes
stationary with respect to the rotating drum but insufficient to
extract liquid out of the load of clothes by the centrifugal force
generated, and performing, between every two of the spraying steps,
a tumbling step for tumbling the load of clothes at a low
rotational speed less than 1 G. After the impregnation, a
centrifugation at a high rotational speed is performed.
Inventors: |
Sans Rovira; Ramon;
(Barcelona, ES) |
Assignee: |
GIRBAU, S.A.
Vic (Barcelona)
ES
|
Family ID: |
41318383 |
Appl. No.: |
12/992931 |
Filed: |
November 28, 2008 |
PCT Filed: |
November 28, 2008 |
PCT NO: |
PCT/ES2008/000745 |
371 Date: |
April 26, 2011 |
Current U.S.
Class: |
8/137 |
Current CPC
Class: |
D06F 35/006 20130101;
D06F 2204/086 20130101; D06F 2204/065 20130101 |
Class at
Publication: |
8/137 |
International
Class: |
D06L 1/20 20060101
D06L001/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 16, 2008 |
ES |
P200801419 |
Claims
1. A spray rinsing method applicable to a clothes washing machine
having a drum with a perforated wall capable of receiving a load of
clothes therein, a controlled motor for rotating said drum about a
substantially horizontal axis in any of the two directions at
variable speeds, and a spraying device capable of introducing
rinsing liquid into the drum, the method comprising the stages of:
rotating the drum at a medium rotational speed greater than 1 G
sufficient to keep the load of clothes stationary with respect to
the rotating drum but insufficient to cause an extraction of liquid
out of the load of clothes by the centrifugal force generated;
impregnating the load of clothes by spraying an amount of said
liquid into the drum and on the load of clothes by means of said
spraying device while the drum rotates at said medium rotational
speed; and increasing the drum rotational speed to a high
rotational speed sufficient to extract a significant proportion of
the liquid out of the load of clothes by the centrifugal force
generated, performing said impregnation with said amount of liquid
by means of a plurality of spraying steps for spraying the liquid
on the load of clothes while the drum rotates at said medium
rotational speed; and performing, between every two of said
spraying steps, a tumbling step for tumbling the load of clothes
with the interruption of the spraying, each tumbling step
comprising reducing the drum rotational speed to a low rotational
speed less than 1 G suitable for performing a tumbling of the load
of clothes inside the drum, such that by means of said combined
spraying and tumbling steps a substantially complete and
homogeneous impregnation of the load of clothes with the amount of
the liquid is obtained before increasing the drum rotational speed
to said high rotational speed.
2. The method according to claim 1, further comprising performing
each tumbling step at said low rotational speed including at least
one reversal in the rotational direction of the drum.
3. The method according to claim 1, wherein said amount of liquid
is a predetermined amount, and in that a fraction of liquid is used
in each spraying step, the sum of said fractions of liquid used in
all the spraying steps being equal to said predetermined amount of
liquid sprayed in the impregnation stage.
4. The method according to claim 3, further comprising using water
as said liquid and adding at least one additive to the water in at
least one of the fractions of liquid.
5. The method according to claim 4, further comprising maintaining
the drum stopped or rotating at one or more rotational speeds
comprised between zero and said medium rotational speed for a time
period for allowing the action of said additive after the
application of at least one of the fractions of water with additive
and before increasing the drum rotational speed to said high
rotational speed.
6. The method according to claim 5, wherein during said time period
for allowing the action of the additive the drum is rotated at one
or more rotational speeds comprised between zero and the low
rotational speed including at least one reversal in the rotational
direction of the drum.
7. The method according to claim 2, wherein during said time period
for allowing the action of the additive the drum is rotated at one
or more rotational speeds comprised between zero and the low
rotational speed including at least one reversal in the rotational
direction of the drum, and further comprising spraying the
predetermined amount of liquid using from 2 to 6 spraying steps for
spraying fractions of liquid in each impregnation stage.
8. The method according to claim 7, further comprising using a
fixed amount of liquid for each of the fractions of liquid and
adapting the predetermined amount of liquid to the type and/or
amount of clothes in the load of clothes by varying the number of
fractions of liquid sprayed in each impregnation stage.
9. The method according to claim 8, further comprising performing a
detachment operation between every two spraying and centrifugation
cycles by rotating the drum at the low rotational speed in
combination with a supply of liquid into the drum by means of the
spraying device.
10. The method according to claim 1, further comprising repeating
said spraying steps and tumbling steps in each impregnation stage
until a detector detects the presence of an amount of the liquid
supplied by spraying at the bottom of a tub inside which the drum
rotates.
11. The method according to claim 2, wherein said amount of liquid
is a predetermined amount, and in that a fraction of liquid is used
in each spraying step, the sum of said fractions of liquid used in
all the spraying steps being equal to said predetermined amount of
liquid sprayed in the impregnation stage.
12. The method according to claim 2, further comprising repeating
said spraying steps and tumbling steps in each impregnation stage
until a detector detects the presence of an amount of the liquid
supplied by spraying at the bottom of a tub inside which the drum
rotates.
Description
TECHNICAL FIELD
[0001] The present invention relates to a spray rinsing method
applicable to a washing process in a washing machine having a
rotating drum, preferably with a horizontal axis and an axial
loading/unloading opening, although it is also applicable to
washing machines with a vertical axis rotating drum. The rinsing
method of the invention is aimed at providing a significant saving
in water, power consumption and additives, preserving the lifetime
of the motor.
[0002] In some cases throughout the present specification, the drum
rotational speeds are expressed by means of G units, where 1 G is
equivalent to the acceleration of gravity, i.e., the rotational
speed which, according to the radius of the drum, causes a
centrifugal acceleration equivalent to the acceleration of gravity
at the level of the cylindrical wall of the drum.
BACKGROUND OF THE INVENTION
[0003] Washings machines of a type provided with a washing tub
capable of containing an amount of liquid, inside which a rotating
drum provided with a perforated wall is assembled, are well known.
The drum is assembled such that it can rotate with respect to a
horizontal or vertical axis and is provided with an axial
loading/unloading opening. An electric motor is arranged to
selectively rotate the drum in any of the two directions at
variable speeds. The tub has a liquid inlet provided with
controlled valve means for introducing an amount of liquid into the
tub and a liquid outlet provided with controlled valve means for
allowing a drainage of the tub.
[0004] Traditionally, in washing machines of this type, after one
or more washing cycles several rinsing cycles are carried out, each
one consisting of a tumbling stage for tumbling the load of clothes
by means of rotations of the drum in alternate directions at a
speed less than 1 G with the tub partially full of a rinsing liquid
followed by a drainage and centrifugation stage. This method has
the drawback of causing a high consumption of rinsing liquid, which
is basically clean water, optionally with additives. In fact, most
of the total amount of water consumed in a washing process is used
in the rinsing cycles. In relation to the additives, they can vary
in each of the several rinsing cycles. For example, in a first
rinsing cycle a bleaching agent could be added to the rinsing
water, in one or more intermediate rinsing cycles, if any, only
water could be used, and in a final rinsing cycle a softening agent
could be added to the rinsing water.
[0005] U.S. Pat. No. 3,811,300, to Unimac, proposes reducing the
number of rinsing cycles by means of a washing machine with a
washing tub, a horizontal axis rotating drum with an axial
loading/unloading opening, and spray nozzles installed in a door of
the loading/unloading opening and directed for the purpose of
spraying clean water on the load of clothes located on the inner
wall of the drum. The operation is as follows. After one or more
washing cycles, a rinsing cycle is performed which consists of
rotating the drum at a relatively high speed so that the load of
clothes remains stationary with respect to the wall of the drum and
continuously spraying clean water on the load of clothes rotating
inside the drum. The centrifugal force generated by the rotation of
the drum makes the rinsing water pass through the clothes and the
perforated wall of the drum. This operation continues for a time
considered to be sufficient for the load of clothes to be
completely rinsed. However, the saving in water by using this
single spray rinsing or "dynamic rinsing" cycle is not effective
because when the drum rotates at a rotational speed sufficient to
assure the extraction of the water by the centrifugal force
generated, the load of clothes is so compacted against the inner
wall of the drum that its capacity to absorb or let water pass
therethrough is highly reduced and it is therefore necessary to
spray a large amount of water to achieve an acceptable rinsing of
the load of clothes.
[0006] Patent DE-A-4013450, to Licentia Patent-Verwaltungs-GmbH,
discloses a rinsing process applied to a rotating drum washing
machine, provided with a device for spraying water into the drum
and controlled by a program. The process corresponds to the stages
depicted in the graph of FIG. 5, where "Vg" is the drum rotational
speed in rpm, "Sa" is the rinsing liquid supply and "t" is the
time. After a washing cycle I, the program proceeds to a rinsing
phase II, during which the drum is rotated at a speed of
approximately 80 rpm (slightly greater than 1 G), such that the
clothes contained in the drum adhere to the inner surface thereof,
forming a ring, and the rinsing water is continuously sprayed on
the clothes from the center of said ring. This spraying phase at
the speed of 80 rpm is interrupted for periods in which the drum is
rotated at a high speed, clearly greater than the washing
rotational speed, to expel the water from the clothes by
centrifugation. This high speed can alternate periods at a speed of
1000 to 1400 rpm with periods at a speed of 200 to 600 rpm. When,
in correspondence with the drum rotational speed, the clothes are
saturated due to having reached the limit in their capacity to
absorb water, the excess water falls in the form of a bath into the
tub. The water in the tub can be detected and used as a signal for
a subsequent development of the program, for example, to interrupt
the spraying of water and perform a tumbling of the clothes at 50
rpm to redistribute the clothes in the drum.
[0007] A drawback of this process of the cited patent DE-A-4013450
is that the tumbling of the clothes at 50 rpm is performed when it
is considered that such clothes are already saturated with water.
In other words, after tumbling the clothes at 50 rpm, no more water
is added and the process passes directly to the centrifugation
phase at speeds ranging from 200 to 1400 rpm. But the fact that the
clothes adhered to the wall of the drum do not absorb more water
and the water supplied by spraying starts to fall to the bottom of
the tub does not assure that all the clothes are uniformly and
homogeneously impregnated, since in those places of the inner
surface of the drum where the clothes are more accumulated the
water will probably not have reached the deepest layers of fabric
whereas in other places where there are not many clothes
accumulated, the layers of fabric will already be saturated and the
water sprayed thereon will fall to the bottom of the tub, leading
the program to interpret that all the clothes are saturated.
Consequently, the rinsing will be defective. Furthermore, the lack
of uniformity and homogeneity in the impregnation of the clothes
would involve a risk of causing negative effects on the clothes if
the process were used to apply additives, such as bleaching agents
and softening agents, with the rinsing water.
[0008] Patent DE-A-4115776, to Licentia Patent-Verwaltungs-GmbH,
describes a rinsing and centrifugation method applicable to a
washing machine with a washing tub, a horizontal axis rotating drum
with an axial loading/unloading opening, and a spraying device for
spraying rinsing liquid into the drum. The Licentia method
comprises, as shown in the graph of FIG. 6 (where "Vg" is the drum
rotational speed in rpm, "Sa" is the rinsing liquid supply and "t"
is the time), after the washing process I, performing an
impregnation and centrifugation process II consisting, first of
all, in draining the washing liquid from the tub and performing a
centrifugation of the load of clothes at a speed of approximately
1000 rpm. The speed is then reduced to approximately 100 rpm
(greater than 1 G) and, when the drum has reached this speed, a
certain amount of water is sprayed into the drum and on the load of
clothes which remains stationary with respect to the wall of the
drum. The drum is then taken to a centrifugation speed of
approximately 800 to 1000 rpm to extract the water by the
centrifugal force generated. After several of such impregnation and
centrifugation operations, a redistribution operation III for
redistributing the load of clothes is performed, reducing the speed
of the drum to a tumbling speed and then spraying a larger amount
of water to detach the load of clothes which has remained adhered
to the inner wall of the drum due to the effect of the centrifugal
force. After the redistribution operation, the speed of the drum is
again increased to approximately 800 to 1000 rpm and then
additional impregnation and centrifugation operations are performed
in the same manner.
[0009] The method described in the cited patent DE-A-4115776 has
some drawbacks. Firstly, the centrifugation at high speed performed
before each spraying operation at medium speed causes an intense
compression of the load of clothes against the inner wall of the
drum and hinders the subsequent penetration of the water in the
clothes, so a part of the sprayed water will be lost without having
performed the rinsing function, and the absorbed water will
impregnate the load of clothes in a non-uniform manner due to the
existence, in the load of clothes applied against the inner wall of
the drum, of areas with different degrees of accumulation and
compression which will not vary substantially during the
consecutive impregnation and centrifugation operations. Therefore,
several consecutive spraying and centrifugation operations without
an intermediate redistribution of the load of clothes mean a
considerable loss of water. Secondly, the rinsing process according
to this method does not allow an efficient application of additives
with the rinsing water due to the fact that a complete and uniform
absorption of the rinsing liquid in the load of clothes cannot be
assured. Thirdly, the large number of centrifugation cycles
required for a complete rinsing involves a high energy cost and,
furthermore, it is detrimental to the lifetime of the driving motor
of the drum.
[0010] Patent EP-A-1254283, to Dyson, describes a method for
rinsing a load of clothes in a washing machine having a perforated
drum rotating about an axis and capable of receiving the load of
clothes therein, and a spraying device capable of spraying water
into the rotating drum. The Dyson method, as shown in FIG. 7 (where
"Vg" is the drum rotational speed, "Sa" is the rinsing liquid
supply and "t" is the time), comprises the following stages.
Firstly, the drum is rotated at a first rotational speed V2
sufficient to keep the load of clothes stationary with respect to
the rotating drum. Then, a volume A of rinsing water is introduced
into the rotating drum through the spraying device, such that the
rinsing water is sprayed on the load of clothes, and then the drum
rotational speed is increased to a second rotational speed V3
sufficient to centrifuge a significant proportion of the rinsing
water out of the load of clothes. The impregnation and
centrifugation cycle C is preferably repeated several times.
[0011] The Dyson method has the drawback of not assuring a complete
and homogeneous impregnation of the load of clothes during the
first impregnation and centrifugation cycle C, because once the
drum has reached the medium rotational speed V2 and the load of
clothes has been stationarily applied to the inner wall of the
drum, the distribution of the load of clothes will substantially
not change, maintaining areas with a higher degree of accumulation
and areas with a lower degree of accumulation on the inner wall of
the drum until the speed of the drum reaches a value less than 1 G
again, which is not expected until the end of the entire rinsing
process made up of the several repeated impregnation and
centrifugation cycles C. The areas having different degrees of
accumulation of the load of clothes on the inner wall of the drum
generally cause a non-homogeneous absorption of the rinsing liquid.
After the second impregnation and centrifugation cycle C, the Dyson
method is very similar to the one discussed above in relation to
the cited Licentia patent DE-A-4115776, and has the same drawback
referring to the low water absorption capacity of the load of
clothes after it has been subjected to an intense compression
against the wall of the drum during the previous centrifugation
operation at high speed, added to the non-homogeneous impregnation
due to the irregular distribution of the load of clothes.
Furthermore, the Dyson method is also unsuitable for performing an
application of additives with the rinsing water due to the
incapacity to assure the complete and homogeneous impregnation of
the load of clothes.
[0012] The cited Dyson patent also claims that the volume A of
rinsing water introduced in the spraying stage is smaller than the
volume required to saturate the load of clothes, such that
substantially all the rinsing water is absorbed inside the load of
clothes. However, it is obvious for any person having ordinary
skill in the art that a load of clothes receiving an amount of
water above the volume required to saturate it will drip, and the
subsequent excess water will be lost water which is useless for the
rinsing function. If, on the contrary, the amount of water sprayed
on the load of clothes is much smaller than the volume required to
saturate it, this will involve the need for a larger number of
spraying and centrifugation cycles to perform the rinsing, with an
increase in the time required, a higher energy consumption and a
greater wear of the motor. The precise volume of water required to
saturate a load of clothes will depend, among other factors, on the
amount of clothes and on the type of fabric. Despite the difficulty
involved in determining it with precision, this "precise" volume is
well known to the persons skilled in washing and rinsing processes
so most manufacturers offer in their washing machines for
industrial use control devices which are pre-programmed to supply
suitable amounts of water to a variety of fabrics and loading
levels during the washing and rinsing cycles, or which can be
programmed by the user to adjust the amounts of water supplied in
each phase of the washing and rinsing operations to each type of
fabric and loading level.
[0013] In view of the cited background documents, the problem to be
solved is how to assure that this "precise" volume of water
required to saturate a load of clothes and which is supplied by
spraying on the load of clothes during an impregnation stage in a
rinsing cycle is effectively absorbed completely and in a uniform
and homogeneous manner by the load of clothes before proceeding to
a centrifugation stage.
DISCLOSURE OF THE INVENTION
[0014] The present invention contributes to solving the previous
problem by providing a spray rinsing method applicable to a clothes
washing machine provided with a drum having a perforated wall
capable of receiving a load of clothes therein, a controlled motor
for rotating said drum about an axis in any of the two directions
at variable speeds, and a spraying device capable of introducing
rinsing liquid into the drum. The method generally comprises, after
a washing and drainage cycle, rotating the drum at a medium
rotational speed (greater than 1 G) sufficient to keep the load of
clothes stationary with respect to the rotating drum but
insufficient to cause an extraction of liquid out of the load of
clothes by the centrifugal force generated, impregnating the load
of clothes by spraying an amount of said liquid into the drum and
on the load of clothes by means of said spraying device while the
drum rotates at said medium rotational speed, and then increasing
the drum rotational speed to a high rotational speed sufficient to
extract a significant proportion of the liquid out of the load of
clothes by the centrifugal force generated. The method of the
present invention is characterized in that it comprises performing
said impregnation of the load of clothes with said amount of liquid
by means of a plurality of spraying steps for spraying the liquid
on the load of clothes while the drum rotates at said medium
rotational speed, and carrying out, between every two of said
spraying steps, a tumbling step for tumbling the load of clothes
with the interruption of the spraying, wherein each tumbling step
comprises reducing the drum rotational speed to a low rotational
speed (less than 1 G) suitable for performing a tumbling of the
load of clothes inside the drum. Thus, by means of the mentioned
combined spraying and tumbling steps, a substantially complete and
homogeneous impregnation of the load of clothes with the amount of
the liquid is obtained before increasing the drum rotational speed
to said high rotational speed.
[0015] In a preferred embodiment, the amount of liquid sprayed is a
predetermined amount which is established according to the amount
and type of clothes to be treated, and said predetermined amount of
liquid is supplied in successive fractions of liquid in the
spraying steps alternated with tumbling steps until reaching a
highly uniform and homogeneous impregnation. Although it is not
essential, it is preferred to not reach the degree of saturation of
the clothes before proceeding to the centrifugation stage for a
better saving in rinsing liquid. Alternatively, the rinsing liquid
can be supplied in successive doses in the spraying steps until it
is considered that the total amount provided is sufficient for a
rinsing stage, for example when the state of saturation of the
clothes has been reached, which can be detected by the presence of
spraying liquid at the bottom of the tub according to a procedure
of the state of the art.
[0016] The method of the present invention further allows an
efficient application of additives together with the rinsing
liquid, which is generally water, as a result of the fact that it
is assured that the rinsing liquid will completely and
homogeneously impregnate the load of clothes. Preferably, after the
application of one or more fractions of water with additive and
before increasing the drum rotational speed to the high rotational
speed for performing the centrifugation, the drum is maintained
stopped or rotating at any rotational speed equal to or less than
the medium rotational speed for a time period considered suitable
for allowing the action of said additive. For example, during said
time period for allowing the action of the additive, the drum can
be rotated at a very low rotational speed, preferably comprised
between zero and the low rotational speed, including one or more
reversals in the rotational direction of the drum to tumble the
load of clothes. These tumbling stages at the very low rotational
speed can be alternated or combined with one or more rotation
stages at the medium rotational speed and/or with one or more
stopping stages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The previous and other features and advantages will be more
fully understood from the following detailed description of
exemplary embodiments with reference to the attached drawings, in
which:
[0018] FIG. 1 is a graph of drum rotational speeds and rinsing
liquid supplies with respect to time in a clothes washing machine
as per a spray rinsing method according to an embodiment of the
present invention;
[0019] FIG. 2 is a schematic depiction of the arrangement of a load
of clothes inside the drum when the latter rotates at a low speed
less than 1 G;
[0020] FIG. 3 is a schematic depiction of the arrangement of a load
of clothes inside the drum when the latter rotates at a medium
speed greater than 1 G;
[0021] FIG. 4 is a graph of drum rotational speeds and rinsing
liquid supplies with respect to time in a clothes washing machine
as per a spray rinsing method according to another alternative
embodiment of the present invention;
[0022] FIG. 5 is a graph of drum rotational speeds and rinsing
liquid supplies with respect to time as per a spray rinsing method
according to a first comparative example of the state of the art
described in the cited patent DE-A-4013450;
[0023] FIG. 6 is a graph of drum rotational speeds and rinsing
liquid supplies with respect to time as per a spray rinsing method
according to a second comparative example of the state of the art
described in the cited patent DE-A-4115776; and
[0024] FIG. 7 is a graph of drum rotational speeds and rinsing
liquid supplies with respect to time as per a spray rinsing method
according to a third comparative example of the state of the art
described in the cited patent EP-A-254283.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0025] Referring first to FIG. 1, the spray rinsing method
according to an embodiment of the present invention is described
below, which method is applicable to a clothes washing machine of a
known type (not shown), having a drum 10 (FIGS. 2 and 3) with a
perforated wall capable of receiving a load of clothes 12 therein,
a controlled motor for rotating said drum 10 about an axis in any
of the two directions at variable speeds, and a spraying device
capable of introducing rinsing liquid into the drum. The drum 10
preferably has a substantially horizontal axis of rotation and an
axial loading/unloading opening, and said spraying device includes
one ore more spraying nozzles installed, for example, in a door of
the mentioned loading/unloading opening and directed towards the
inner wall of the drum. The rotational speeds and directions of the
drum as well as the supplies of water or rinsing liquid through the
spraying device are generally controlled with respect to time by a
pre-programmed or programmable control device.
[0026] As shown in the graph of FIG. 1 (where "Vg" is the drum
rotational speed, "Sa" is the rinsing liquid supply and "t" is the
time), the method of the present invention comprises, first of all
and generally after a washing operation, impregnating a load of
clothes 12 contained in the drum 10 by spraying a predetermined
amount of said liquid A into the drum 10 and on the load of clothes
12 by means of the spraying device while the drum rotates at a
medium rotational speed V2 (greater than 1 G and generally less
than 20 G) (see also FIG. 3) sufficient to keep the load of clothes
12 stationary with respect to the rotating drum 10 but insufficient
to cause an extraction of liquid out of the load of clothes by the
centrifugal force generated by the rotation, and then increasing
the drum rotational speed to a high rotational speed V3 (generally
greater than 50 G and up to 300 G or more) sufficient to extract a
significant proportion of the liquid out of the load of clothes by
the centrifugal force generated. The mentioned predetermined amount
A of liquid will preferably be an amount of liquid equal to or
slightly less than the amount of liquid which is considered
hypothetically necessary to saturate the load of clothes. The
impregnation stage M for impregnating the load of clothes 12 with
the predetermined amount A of liquid and the subsequent
centrifugation stage N together constitute an impregnation and
centrifugation cycle C which can be repeated a number of times
until achieving a satisfactory rinsing.
[0027] It will be observed that, according to the method of the
present invention, the predetermined amount A of liquid for
impregnating the load of clothes 12 is not provided all at once,
but rather it is divided into fractions A1, A2, . . . An of liquid
which are supplied by means of respective spraying steps for
spraying on the load of clothes 12 while the drum rotates at said
medium rotational speed V2, and between every two of said spraying
steps a tumbling step for tumbling the load of clothes is carried
out for a time period in which the spraying is interrupted. Each
tumbling step comprises reducing the drum rotational speed to a low
rotational speed V1 (less than 1 G) (see also FIG. 2) suitable for
performing a tumbling of the load of clothes inside the drum and
maintaining this low rotational speed V1 for a predetermined
period. Each tumbling step at said low rotational speed V1
preferably includes one or more reversals in the rotational
direction of the drum indicated in the graph of FIG. 1 as +V1 and
-V1. Optionally, an additional tumbling step can be performed after
spraying the last fraction of liquid An and before the
corresponding centrifugation stage N. It will be understood that
although the medium rotational speed V2 and high rotational speed
V3 have all been indicated in the graph in the positive direction,
the rotations at these speeds can also be performed in the reverse
direction or alternately in opposite directions in the different
steps or cycles without departing from the scope of the present
invention.
[0028] As shown in FIG. 3, during the spraying steps of the
fractions A1, A2, . . . An of liquid, when the load of clothes 12
is arranged in a stationary manner with respect to the wall of the
drum 10 due to the effect of the centrifugal force greater than 1 G
(and generally less than 20 G) generated by the rotation of the
drum 10 at the medium rotational speed V2, the load of clothes 12
is irregularly distributed, with areas with a higher degree of
accumulation and areas with a lower degree of accumulation, on the
inner wall of the drum 10, which can cause an irregular absorption
of the liquid in the clothes. During the tumbling steps, as shown
in FIG. 2, given that the low rotational speed V1 causes a
centrifugal force less than 1 G, the clothes are detached due to
the effect of gravity from the inner wall of the drum 10 at the
upper part and fall on the clothes at the lower part of the drum
10, such that the tumbling of the load of clothes 12 causes a
loosing and a change of position of the clothes and a mechanical
work facilitating the absorption and homogenization of the
fractions A1, A2, . . . An of liquid which are sprayed in the
successive spraying steps. Thus, by means of the alternate
combination of spraying steps and tumbling steps according to the
present invention a substantially complete and homogeneous
impregnation of the load of clothes 12 with the predetermined
amount A of the liquid can be obtained before increasing the drum
rotational speed to the high rotational speed V3 to perform the
centrifugation and make the liquid pass through the clothes and
through the perforated wall of the drum in order to perform the
rinsing, according to the process disclosed by the cited patent
U.S. Pat. No. 3,811,300, to Unimac.
[0029] As has been stated above, the impregnation and
centrifugation cycle C can be repeated a number of times until
achieving a satisfactory rinsing. One embodiment contemplates
performing from 2 to 6complete spraying and centrifugation cycles C
for a rinsing, depending on the amount and type of clothes in the
load of clothes, the quality of the water, the detergent used in
the previous washing operations, etc. Between every two of said
impregnation and centrifugation cycles C the method comprises
performing a detachment operation D consisting of a supply of
liquid Ad into the drum 10 by means of the spraying device while
the drum is rotated at the low rotational speed V1. This supply of
liquid Ad increases the weight of the clothes and contributes to
the latter being detached from the inner wall of the drum 10 after
the centrifugation. Optionally, the amount of liquid Ad sprayed
during the detachment operation D and which will be absorbed by the
load of clothes can be considered as one of the fractions of liquid
to be deducted from the fractions A1, A2, . . . An of the following
impregnation stage M.
[0030] The sum of all the fractions A1, A2, . . . An of liquid used
in the different spraying steps of an impregnation and
centrifugation cycle C is equal to the predetermined amount A of
liquid sprayed in the impregnation stage M. The liquid used can be
water alone or water with additives. The fact of supplying the
predetermined amount A of liquid in fractions A1, A2, . . . An
allows, for example, adding one or more additives to the water in
one or more of the fractions A1, A2, . . . An of liquid selected.
For example, in one or more of the spraying steps of the first
impregnation stage M a bleaching agent could be added to the water
of the corresponding fractions A1, A2, . . . An, and in one or more
of the spraying steps of the last impregnation stage M a
neutralizing or softening agent could be added to the water of the
corresponding fractions A1, A2, . . . An. The complete and
homogeneous impregnation of the load of clothes with the
predetermined amount A of rinsing liquid including the additives,
achieved by means of the alternate spraying and tumbling steps,
allows a more precise metering and a better exploitation of the
additives, which translates into a saving in additives and into
clean clothes without excess additives.
[0031] Alternatively, the total amount of liquid to be sprayed in
the impregnation stage M is not known beforehand and is determined
during the cycle when it is detected that the load of clothes is
saturated. The state of saturation of the load of clothes can be
detected, for example, when after several spraying and tumbling
steps a detector detects the presence of an amount of the liquid
from the spraying at the bottom of a tub inside which the drum
rotates, which indicates that the load of clothes is incapable of
absorbing more liquid because it is saturated, and the excess
liquid falls to the bottom of the tub.
[0032] The graph of FIG. 4 (where "Vg" is the drum rotational
speed, "Sa" is the rinsing liquid supply and "t" is the time) is a
variant of the graph of FIG. 1 including a first rinsing cycle C
with an impregnation stage M including the application of
additives, during which a predetermined amount A of liquid
composed, for example, of water with one or more additives, is
supplied. As in the example described above, in the first cycle C
of FIG. 4, the predetermined amount A of liquid is supplied by
means of several spraying steps for spraying fractions A1, A2, . .
. An of liquid while the drum rotates at the medium rotational
speed V2. Between every two spraying steps for spraying the
fractions A1, A2, . . . An of liquid, a tumbling step comprising
alternate rotations of the drum in both directions at the low
rotational speed +V1, -V1 is performed. Thus, at the end of the
spraying step for spraying the last fraction An of liquid, the load
of clothes will be completely and homogeneously impregnated with
the predetermined amount A of water and additives. Then, this
variant of the method comprises maintaining the drum stopped or
rotating at one or more rotational speeds comprised between zero
and the medium rotational speed V2 for a time period T considered
sufficient or suitable for allowing the action of the additive or
the additives impregnating the load of clothes together with the
water. The cycle C ends with a centrifugation stage N in which the
liquid is substantially extracted from the load of clothes by the
centrifugal force generated by the rotation of the drum at the high
rotational speed V3.
[0033] In the graph of FIG. 4, the mentioned period T comprises
first of all a tumbling of the impregnated load of clothes inside
the drum at a very low rotational speed, less than the low
rotational speed V1, including one or more reversals in the
rotational direction of the drum to perform a light-duty mechanical
work, followed by a rest period during which the rotation of the
drum is stopped, and by a period of rotation at the medium
rotational speed V2 during which the load of clothes remains
stationary with respect to the wall of the drum, before the
centrifugation stage N. However, the example of FIG. 4 is merely
illustrative, and variations with respect to the modes of rotation
of the drum to be performed during the time period T for allowing
the action of the additive or additives depending on the type of
fabric and the class of additives will readily occur to a person
skilled in the art. For example, during the entire time period T
the drum could remain stopped or could remain rotating at a
constant rotational speed less than the low rotational speed V1 or
comprised between the low rotational speed V1 and the medium
rotational speed V2, or alternatively it could remain rotating at a
rotational speed less than the low rotational speed V1 including
reversals in the rotational direction. Likewise, two or more of the
modes of rotation shown in the period T of FIG. 4 could be combined
in a different order.
[0034] Generally, whichever the embodiment, the number of spraying
steps for spraying fractions A1, A2, . . . An of liquid in each
impregnation stage M will be determined by different factors, such
as the type of fiber and/or fabric from which the load of clothes
is formed, or the hardness of the water, and will generally be from
2 to 6, although it is not ruled out that it can be more than six.
To adapt the predetermined amount A of liquid used in each
impregnation stage M to the type and/or amount of clothes forming
the load of clothes arranged inside the drum 10, the amount of
liquid of the several fractions A1, A2, . . . An can be varied, or,
alternatively, a fixed amount of liquid can be sued for each of the
fractions A1, A2, . . . An of liquid and varying the number of
fractions A1, A2, . . . An of liquid sprayed in each impregnation
stage M.
[0035] It must be taken into account that in FIGS. 1 and 4, for the
sake of greater clarity of the drawing, the heights in the speed
axes and the distances in the time axes are altered and
disproportionate with respect to their respective actual scales and
must not be interpreted literally.
[0036] A person skilled in the art will be capable of performing
modifications and variations based on the embodiments shown and
described without departing from the scope of the present
invention.
[0037] FIGS. 5, 6 and 7 show comparative graphs corresponding to
spray rinsing methods known in the state of the art. The graph of
FIG. 5 corresponds to the cited patent DE-A-4013450 to Licentia,
the graph of FIG. 6 corresponds to the cited patent D -A-4115776 to
Licentia, and the graph of FIG. 7 corresponds to the cited patent
EP-A-254283 to Dyson, as they have been discussed above in relation
to the background of the invention. It will be observed that, in
the methods of the state of the art illustrated in FIGS. 5, 6 and
7, the amount of rinsing liquid necessary for each impregnation
stage is supplied by continuously spraying while the drum rotates
at a medium speed V2 (slightly greater than 1 G) before each
centrifugation stage at a high speed V3. On the contrary, in the
method of the present invention illustrated in FIGS. 1 and 4, the
amount of rinsing liquid A necessary for each impregnation stage is
supplied distributed into different fractions A1, A2, . . . An
while the drum rotates at a medium speed V2 (slightly greater than
1 G), alternated with tumbling steps, in which the spraying is
interrupted and the drum rotates at a low speed V1 (less than 1 G),
before each centrifugation stage at a high speed V3.
[0038] The scope of the present invention is defined in the
attached claims.
* * * * *