U.S. patent application number 11/140393 was filed with the patent office on 2005-12-29 for household laundry washing machine with improved spinning phase.
This patent application is currently assigned to Electrolux Home Products Corporation N.V.. Invention is credited to Altinier, Fabio, Galassi, Stefano, Giovagnoni, Marco.
Application Number | 20050284192 11/140393 |
Document ID | / |
Family ID | 34929243 |
Filed Date | 2005-12-29 |
United States Patent
Application |
20050284192 |
Kind Code |
A1 |
Altinier, Fabio ; et
al. |
December 29, 2005 |
Household laundry washing machine with improved spinning phase
Abstract
Washing machine comprising a rotating drum, an electric motor
apt to put the drum into rotation, measurement means of the drum
rotational speed, means able to detect the torque provided by said
motor, computing and control means able to determine and control
the instantaneous speed of the drum, wherein, before of the
spinning phase, said computing and control means activates the
machine into rotation at a predefined speed (Wmain) with the
laundry retained on the drum inner wall, compute the static
unbalance (m) and the elevation moment (Mel), check if both the
following conditions are met: the static unbalance mass (m) is less
than a pre-determined value and the absolute value of the elevation
moment is less of a predetermined value; if at least one of the
unbalancing mass values, or one of the values of said elevation
momentum (Mel) are higher than a predetermined respective values,
said computing means calculate the difference between the value of
said unbalancing mass and the respective said predetermined maximum
value, and if said difference is higher than a predetermined limit,
said computing and control means will command a predermined speed
increase; if not, they command a predetermined speed reduction.
Inventors: |
Altinier, Fabio; (Porcia,
IT) ; Galassi, Stefano; (Porcia, IT) ;
Giovagnoni, Marco; (Udine, IT) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
Electrolux Home Products
Corporation N.V.
Zaventem
BE
|
Family ID: |
34929243 |
Appl. No.: |
11/140393 |
Filed: |
May 27, 2005 |
Current U.S.
Class: |
68/12.06 ;
68/23R |
Current CPC
Class: |
D06F 35/007 20130101;
D06F 2103/26 20200201; D06F 33/48 20200201; D06F 2103/24 20200201;
D06F 37/203 20130101; D06F 2105/54 20200201; D06F 33/40
20200201 |
Class at
Publication: |
068/012.06 ;
068/023.00R |
International
Class: |
D06F 033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2004 |
EP |
04 102 927.3 |
Claims
1. Washing or washing-drying machine comprising: a rotating drum,
an electric motor apt to put the drum into rotation, measurement
means of the drum rotational speed, means able to detect the torque
provided by said motor, computing and control means able to
determine and control the instantaneous speed, characterized in
that, before of beginning the spinning phase, said computing and
control means: do make the measurement of the total drum inertia
(J.sub.TOTAL), activate the machine into rotation at a predefined
speed .OMEGA..sub.MAIN (2) corresponding to a complete laundry
distribution retained on the drum inner cylindrical surface,
compute the static unbalance mass (m) and the elevation torque
(T.sub.ELEVATION).
2. Washing machine according to claim 1, characterized in that,
after having performed the operation of claim 1, said computing and
control means determine a working mode according to which they
activate the spinning phase if both of the following conditions are
met: the static unbalance mass (m) is less than a pre-determined
value (S) (6), and the absolute value of the elevation torque is
less than a predetermined value (T.sub.ELEVATION.sup.MAX) (7), said
unbalance mass and said elevation torque being calculated according
to the drum total inertia, and said conditions being checked also
in times not successive to said calculations.
3. Machine according to claim 2, characterized in that, is at least
one of the unbalance mass values (m), on or more of the absolute
values of the elevation torque (T.sub.ELEVATION) are higher than
the respective predetermined values, (S, T.sub.ELEVATION), said
computing means calculate the difference between the value of said
unbalance mass (m) and the respective said predetermined maximum
Value (S), and if said difference is less than a predetermined
limit (.beta..multidot..vertline.- T.sub.ELEVATION.vertline.) (9),
said computing and control means will command a predetermined speed
increase (10).
4. Machine according to claim 2, characterized in that, if at least
one of the values of said unbalance mass (m) or of said absolute
value of the elevation torque (T.sub.ELEVATION) are higher of a
respective pre-defined value, said computing means calculate the
difference between the value of said unbalance mass (m) and the
respective said maximum predetermined limit (S), and if said
difference is higher than a predetermined limit
(.beta..multidot..vertline.T.sub.ELEVATION.vertline.) said
computing and control means will command to the drum a
predetermined speed reduction (12).
5. Machine according to claim 3 or 4, characterized in that, after
having achieved said predetermined speed increase or decrease, said
computing means check whether the resulting speed is comprised into
a pre-defined interval (.OMEGA..sub.MINd.div..OMEGA..sub.MAZd (27,
28) and if such condition is positively met, a further comparison
is made (29) whether the working time from the beginning of the
operation as per claim 1 is less than a predefined maximum time
interval t.sub.M, and if such condition is met the machine
operation is brought to the beginning of claim 2 (5).
6. Machine according to claim 3 or 4, characterized in that of the
resulting speed is outside of a predefined speed interval
(.OMEGA..sub.MINd.div..OMEGA..sub.MAZd), said computing and control
mans activate the drum to rotate at a predefined speed
(.OMEGA..sub.MINd or .OMEGA..sub.MAZd) (27B, 28B) and after that a
further comparison is made (29) whether the working time from the
beginning of the operation as per claim 1 is less than a predefined
maximum time interval (t.sub.M), and if such condition is met the
machine operation is brought to the beginning of claim 2.
7. Machine according to claim 1, characterized in that said
computing and control means are able to perform the following
operation: before of commanding the spinning phase, they command
the drum speed (21) to the predetermined speed (.OMEGA..sub.MAIN)
as in claim 1, and then the machine operation is brought to the
beginning of claim 2.
8. 8. Machine according to claim 7, characterized in that, after
having determined the drum speed, it is able of check that: the
drum speed is the same of said predetermined speed
(.OMEGA..sub.MAIN, 23), and said unbalance mass (m) is less of a
predetermined value (S; 24), and if said check gives a positive
result, it increments the number of said operations in a specific
adding register (25), and if the actual number in said register is
the same of a predetermined number (N, 26), then said computing and
control means command the spinning phase.--
Description
[0001] The present invention relates to a laundry washing or to a
laundry washing-dryer machine provided with means able to detect
the unbalance mass and to balance the laundry load before the
spinning phase. It is well known during an operating program of
laundry washing/drying machine to have one or more spinning phases,
i.e. drum rotation phases at much higher speed than normally
foreseen during the actual washing phases.--
[0002] A basic element concerning said spinning phases is the risk
of having an unbalanced laundry load with the clothes arranged
unevenly inside the machine drum, i.e. accumulated in some definite
areas and not available in other areas, so that during high speed
rotation of the drum this unbalanced load condition may in fact
cause remarkable oscillations or even the risk of a mechanical
failure.--
[0003] To this purpose the presently available washing machines (or
washing-dryer machine) are provided with special control systems
and methods to check whether the laundry load is evenly distributed
or balanced inside the drum before the execution of the spinning
phase, whereas in case of an unbalanced load the control system
will remove the unbalance condition and provide for a new
distribution phase or at least bring its amount back to acceptable
limits to the machine structure.--
[0004] The techniques to achieve this goal are mainly based on
measuring the variation of the drum speed during the starting time
of the spinning phase, and on correlating said speed variation to
the unbalance level.--
[0005] Indeed in a drum with an unbalanced load, moving at a
constant rotation speed, the presence of an unbalanced load causes
an increase in the drum speed in the time interval when the load is
in the descending phase, and causes it to slow down when it is in
the ascending phase.
[0006] As a result the drum speed takes an oscillatory behaviour
around an average speed, well known to the man skilled in the art,
and that for the sake of brevity is no further described.
[0007] According to the prior art, as in the exemplary patents EP
1342826, EP 0335790B1 and FR 2577949, such an oscillatory speed
behaviour is then detected, processed and used in order to generate
some procedures of drum rotation aimed to avoid or reduce the
detected unbalance mass.--
[0008] However said solution shows some drawbacks mainly based on
the fact that the inertia moment of the loaded drum is not detected
and then not considered in the processing and balancing
procedure.--
[0009] The inertia moment is however most important as it is well
known that it directly affects the drum oscillation during the
spinning phase; indeed in a drum having an unbalanced load, if the
overall drum inertia is increased, i.e. if the laundry load is
increased, the resulting oscillation during the spinning phase is
reduced accordingly.--
[0010] And on the contrary, if the inertia moment is reduced, that
is if the laundry load is partly removed from the drum, maintaining
the initial unbalance mass, then the speed oscillation
increases.--
[0011] Therefore some specific conditions can come true, wherein
during the spinning phase the drum is subjected to an excessive
oscillations that are prejudicial to the machine safety, even if an
acceptable unbalance mass still exists.--
[0012] A further method to control the unbalance mass is to
directly measure the same unbalance mass, i.e. to measure the
vibrations of the washing group by using one o more
accelerometers.--
[0013] Based on the measured values, a procedure is started which
is aimed to redistribute the load according to known methods.--
[0014] However this solution requires a not negligible computing
power, expensive additional sensors, and moreover the unbalance
mass evaluation can be done, with adequate confidence, only when
the drum speed is so high that the laundry load is retained on the
drum inner surface.--
[0015] Largely known in the art is a different technique of
controlling within proper limits the drum unbalance mass, and
consisting in directly counterbalancing said unbalance mass; said
technique is implemented by using adequate and generally circular
conduits placed solidly with the drum and that are coaxial with it,
and that contain some rotating or floating masses, typically water,
or oil, or rollers or spheres; said masses are made to rotate by
the drum rotation and soon they tend to distribute themselves in
their own accord in a respective position able to at least
partially balance the unbalance mass of the laundry load contained
in the drum.
[0016] Said solutions are exemplified in the European patent appl.
n. 96114328.6, in WO 93/23687 and also in the patents therein
cited.
[0017] Said solutions of automatic re-balancing have shown
effective from a functional point of view, but also burdensome and
complicated in the construction, and furthermore they are also
degrading the performances as the annular chambers, containing the
balancing masses, take up a room that otherwise could have be taken
by the laundry articles.
[0018] It would therefore be desirable, and is actually a main
purpose of the present invention, to provide a clothes washing or
washing-drying machine that will eliminate, or at least reduce the
drawback of the unbalance mass produced by the uneven laundry
distribution inside the drum during the spinning phases at high
speed, considering also the actual inertia of the arm containing
the laundry load.--
[0019] According to a further purpose of the present invention this
clothes washing machine (or washing-dryer machine) shall be able to
be easy manufactured by using existing, ready available materials
and techniques, and be competitive in its construction without
suffering any alteration or reduction in the performance and
reliability thereof.
[0020] These aims are reached in a washing machine (or in a
washing-dryer machine) incorporating the characteristics as recited
in the appended claims and including such operating modes as
described below by mere way of non-limiting example with reference
to the accompanying figures, in which:
[0021] FIG. 1 is a simplified flow-chart of the basic operations
and logical checks in a washing machine (or washing-dryer machine)
according to the invention.
[0022] FIG. 2 is a complete flow-chart of the basic operations and
logical checks in a washing machine (or washing-dryer machine)
according to the invention.
[0023] FIG. 3 is a diagram of a number of electrical signals
representing various parameters in a washing machine (or
washing-dryer machine) working according to the flow chart of FIG.
2.--
GENERAL PRINCIPLES
[0024] The requirements of the distribution strategy according to
the instant invention are now generally described, and the
description of the operating modes and of the computations, aimed
to define the needed parameters, are deferred further on.--
[0025] In order to obtain a good balance of the laundry load it is
needed:
[0026] to measure its unbalance mass, and,
[0027] to find out the best distribution strategy.--
[0028] As well known, the unbalance mass can be calculated from the
static laundry unbalance mass; said static unbalance mass can be
measured by making an energy balance on an integer number of drum
turns.--
[0029] Therefore an initial measurement of the inertia moment of
the total drum (comprising drum, the whole laundry load and the
motor), and the continuous measurements (i.e. lasting for the whole
time interval of the distribution process) of the angular drum
speed and of the motor torque have to be carried out.
[0030] In order to obtain a good balance of the laundry load it is
needed to find out the best distribution strategy according to the
unbalance mass, which of course can be varying during the spinning
starting phase; moreover the said distribution strategy has to be
able of automatically changing itself according to the changing of
the unbalance mass.--
[0031] The laundry movement inside the drum is random, not
foreseeable and in the facts not controllable from the outside;
then, if a favourable situation takes place, it is advisable to try
to freeze it as quick as possible, by increasing the rotation
speed.--
[0032] From this point of view it is then useful to drive the drum
at a suitably high speed, so that the laundry load is fully
retained on the drum inner surface.--
[0033] On the other side, with the increase of the rotation speed,
the portion of the laundry load not yet retained against the drum
inner surface tends to decrease, and that may prevent the reduction
of the unbalance mass in excess with respect to the maximum allowed
value for the unbalance mass.--
[0034] As a conclusion, the speed control during the laundry
distribution process has to duly take into account said two clashed
elements; practically speaking, the rotational speed must be
controlled in such a way to be the highest possibly, having taken
into account that the possibility of eliminating the unbalance mass
in excess (with respect to the maximum acceptable unbalance degree)
shall not be excluded.--
[0035] The requirements of the distribution strategy according to
the instant invention are now explained.
[0036] Definitions
[0037] The general equilibrium equation with reference to the
rotational speed of the drum with the laundry load is: 1 J TOTAL t
= - mgR cos ( t ) + T MOTOR + T FRICTION + T ELEVATION
[0038] wherein the various terms show the respective following
meanings:
[0039] J.sub.TOTAL is the total inertia of the rotating masses,
comprising the laundry load, the drum and the electric motor,
respect to the drum axis.
[0040] .omega. is the drum angular speed.
[0041] m is the static unbalance mass.
[0042] d.omega./dt is the drum angular acceleration.
[0043] g is the gravity acceleration.
[0044] R is the drum radius.
[0045] mgR.multidot.cos(.omega.t) is the resistant moment due to
the static unbalance mass m (it is an oscillatory value).
[0046] T.sub.MOTOR is the torque provided by the electric motor and
measured on the drum axis.
[0047] T.sub.FRICTION is the friction torque measured on the drum
axis.
[0048] T.sub.ELEVATION is the torque, measured on the drum axis,
needed to raise the portion of the laundry load that is not yet
retained on the drum inner surface, without the friction effect and
of the inertial effect.
[0049] The overall inertia on the drum axis (J.sub.TOTAL) must be
measured once and for all at the beginning of the laundry
distribution process, as it is a value that is stable, when the
laundry humidity is constant.
[0050] The friction torque on the drum axis (T.sub.FRICTION) takes
into account all the frictions developed by the machine, comprising
both the ball bearings and the gear friction, and those related to
the laundry rubbing.--
[0051] The elevation torque on the drum axis (T.sub.ELEVATION) is
the resistant torque due to the laundry not yet retained by the
centrifugal force on the drum inner surface; indeed in its
downwards motion the not yet retained laundry doesn't make any
resisting torque, as it doesn't drags the drum with it, while it
makes a restraining torque in its upwards motion.
[0052] The energy supplied by the motor to raise the laundry is
then dispersed by friction in the warping motion of the laundry
load (falling impact and rubbing due to the relative motion among
the laundry articles). The elevation torque is then a negative
moment, as the friction torque is.
[0053] The parameters used in the distributing procedure are the
static unbalance mass (m) and the elevation torque
(T.sub.ELEVATION).--
[0054] They can be obtained by using the given general equation to
calculate an energy balance over an integer number of drum turns.
Therefore an integration of the same equation between an initial
angle .theta..sub.1 and a final angle
.theta..sub.2=.theta..sub.1+2.pi.N, has to be calculated, N being
an integer number.--
[0055] As the resistant torque generated by the static unbalance
mass -mgR.multidot.cos(.omega.t) shows a sinusoidal behaviour with
respect to the drum rotation angle, then the unbalance mass amount
can be estimated by the following equation, valid for any initial
angle .theta..sub.1: 2 1 1 + 2 - mgR cos = 4 mgR
[0056] In order to use the main equation that allows the
instantaneous determination of the amount of the unbalance mass (m)
and of the elevation torque (T.sub.ELEVATION), it is requested to
measure two parameters: the drum angular speed (.omega.), and the
motor torque (T.sub.MOTOR).--
[0057] However here it is intended that the relevant amounts are
well known, as they can be easily detectable with known means and
procedures; for instance by using a tachometer generator and
measuring the current taken up by the motor, with respect to its
phase; therefore their measurements and processing are no further
discussed.--
[0058] Distribution Strategy of the Laundry Load
[0059] The elevation torque (T.sub.ELEVATION) can be referred as
the parameter of the percentage of the laundry load not retained to
the inner wall of the drum; if said moment is zero, the laundry
articles are fully retained on the drum inner surface, while as
much this parameter increases in its absolute amount (being it a
negative amount) as the laundry load is allowed to move
itself.--
[0060] By using the correlation between the elevation torque and
the mobility degree of the laundry load, it is possible to define
an advantageous and effective strategy for the distribution
process.--
[0061] According to the above considerations, the procedure for
starting the spinning phase without suffering an excessive
unbalance mass will have to consider the following
observations:
[0062] The laundry motion inside the drum is a random and not
foreseeable movement, and in fact not controllable from the
outside.
[0063] The only thing that can be done is to wait that a condition
of low unbalance mass takes place.
[0064] If a favourable condition takes place, it is requested to
freeze it as quick as possible, by increasing the rotation
speed.
[0065] The higher is the rotation speed, the easier is the freezing
of a favourable condition when it takes place.
[0066] The lower is the rotation speed, the higher is the laundry
mobility degree, i.e. the load percentage not retained in a
substantially fixed position related to the drum.
[0067] In order that a favourable condition can take place, it is
requested that the laundry can be moved with a basically high
mobility degree, so that the possibility of eliminating the
unbalance mass in excess (with respect to the maximum accepted
unbalance degree) is not preliminarily excluded.--
[0068] If all these facts are taken into account, it is concluded
that the best distribution strategy consists in the adoption of a
rotating drum speed during the whole distribution phase that be the
maximum possible speed, however compatible with a laundry mobility
degree good enough to allow the possibility of eliminating the
unbalance mass in excess measured each time.--
[0069] In order to implement such strategy and in order to control
properly the target speed during the distribution process, the
following condition must be implemented:
m-S<.beta..multidot..vertline.T.sub.ELEVATION.vertline.
[0070] In it, m represents the static unbalance mass measured at
the actual time, while S gives the threshold, i.e. the maximum
allowed limit for the unbalance mass; therefore m-S represents the
unbalance mass in excess that is requested to compensate.
[0071] .beta. is a suitably selected constant value.
[0072] If the check of the above given condition is positive (the
condition is true), that means that the laundry articles have not
been fully distributed on the drum wall, but a part of them are
still "flying" inside it, due to the fact that the drum speed is
too low. Therefore a limited increase of the drum speed is
activated.--
[0073] If the check of the above condition is negative, (the
condition is not true), that means that the unbalance mass is too
high, independently of the fact that the laundry articles are or
not retained on the drum inner wall. Then a small decrease in the
drum speed is activated, in order to separate a further portion of
the laundry load from the drum inner wall and to reposition it in a
more balanced way.--
[0074] The optimum condition, that permits to start the spinning
phase with a well balanced load, is implemented when the unbalance
mass is low enough and, in the same time, the elevation torque is
close enough to zero, (i.e. when the laundry load appears to be
well distributed in the drum and with a left-over mobility close to
zero).--
[0075] That means that the following two conditions have to come
true: 3 { m S T ELEVATION T ELEVATION MAX
[0076] where T.sub.ELEVATION.sup.MAX is the maximum allowable
amount for the absolute value of the elevation torque.
[0077] As a matter of facts, the distribution strategy must consist
in that the spinning phase is allowed only after two basic
conditions are implemented, i.e.:
[0078] COND 1: the unbalance mass must be less than a maximum
pre-determined value, and it has to be measured just before of
starting the spinning phase, i.e. when:
[0079] COND 2: the whole laundry load is almost fully distributed
on the drum inner wall, that is the elevation torque is less than a
maximum predefined amount.--
[0080] Such strategy can be effectively understood, in the actual
case of a washing machine (or a washing-dryer machine) just before
the spinning phase, considering the logical flow-chart of FIG. 1,
representing in a simplified form the operating sequence of the
various logical and control operations in a washing machine (or in
a washing-dryer machine) according to the invention.--
[0081] In order to simplify and to make easier the understanding of
the invention, said logical flow-chart shows only the working modes
of a logical and working kind that are essential to implement the
invention; in the real situation however of a washing machine (or a
washing-dryer machine) that actually implements the invention, it
is needed and useful to introduce some further operations and
logical functions; these are described in FIG. 2 which represents
all working operations and functions in a washing machine for
actual use.
[0082] In the flow-chart of FIG. 1 each block is identified by a
specific number, that is used in the following description in order
to describe the operation modes of the respective blocks:
[0083] Block 1. The spinning phase is started; in said phase the
motor is activated so that it speeds-up the drum speed till to a
pre-determined speed.
[0084] Block 2. Said pre-determined speed .omega..sub.MAIN is
reached; said speed is the minimum speed when the laundry load is
wholly distributed on the drum inner surface; usually said speed is
around 110 rpm.
[0085] Block 3. The measurement of the inertia moment J.sub.TOTAL
of the drum, comprised of the laundry load, is done; the
measurement of said value can be easily calculated with known means
and procedures, for instance by the detection of the torque and of
the drum angular acceleration; as these operations are well known
in the prior art, they are not further explained.--
[0086] Block 4. The average friction torque on one turn
(T.sub.FRICTION) in the condition where the laundry load is
retained on the drum inner surface is measured; it corresponds (but
the sign) to the average torque supplied by the motor and needed to
exceed the friction in condition of stable target speed, the
laundry being retained by the drum.
[0087] Block 5. The unbalance mass m and the elevation torque
T.sub.ELEVATION are calculated; the two parameters are now
calculated at the actual speed that usually is different from the
speed in the previous block 4, as the latter speed has been
modified by the loop comprising the block 11 described further on,
wherein the actual speed has been accelerated or decelerated by a
limited amount.--
[0088] Block 6. In this block the test is done whether the
unbalance mass m is less than a predefined value S; if such test is
confirmed, the operation goes on to the following step in the block
7; said first check is a basic step, as it implements the first of
the two conditions seen above (COND 1).
[0089] Block 7. In this logical block the test is done whether the
module of the elevation torque T.sub.ELEVATION is less than a
maximum specified value T.sub.ELEVATION.sup.MAX; this second test
implements the second condition given above (COND 2).--
[0090] Block 8. If said second condition too is confirmed, the
spinning phase is started without further tests, measures and/or
calculations, as the two conditions required of a small and
acceptable unbalance mass, combined with a fairly even distribution
of the laundry load on the drum inner surface, are
accomplished.
[0091] Block 9. If, on the contrary, in the logical block 6 the
unbalance mass m is not less than the specified limit value S, or
if at the logical block 7 the elevation torque T.sub.ELEVATION is
not less than the respective specified maximum value, that means
that at least one of the two main conditions (COND 1, or COND 2)
are not met; therefore it is needed to work out the logical
operation of checking whether
m-S<.beta..multidot..vertline.T.sub.ELEVATION.vertline., wherein
.beta. is a properly defined constant. If such test is met, it
means that the laundry is not completely distributed on the drum
inner surface, but is still "flying" into it, obviously due to the
fact that the drum speed is too low. In order to overcome such
problem the operation goes on to the following block 10.
[0092] Block 10. In said block a small step-up of a predetermined
amount is actuated on the drum speed, of course in order to make
the laundry to better adhere to the drum inner surface.
[0093] Block 11. After the drum speed variations, the routine of
the calculations and of the related tests, previously described in
the logical block 5 on, is initiated until the condition in block 7
is met, so that it is now possible to start the spinning phase.
[0094] Block 12. If in the previous block 9 the given condition is
not met, that means that the unbalance mass is excessive,
independently of the fact that the laundry load is or not adhering
to the drum inner surface; in order to overcome such constraint, a
reduction of a predetermined amount is activated on the drum speed,
to allow that the load into the drum is separated and is
re-distributed in a more even way; of course that can be not
obtained in the first attempt, but this result can be easily
attained with a sequence of different attempts at progressively
lower speeds, as activated by the logical loop going from the block
11 towards the block 5.--
[0095] The flow-chart of FIG. 1 is effective to illustrate the
logical and functional ground of the invention; however in an
actual washing machine (or washing-dryer machine), intended for a
real household use, it is needed to introduce in the working
process a number of further checks in order to make it safer and
that in any case determine some limit values, beyond which the
washing cycle is stopped in any case.--
[0096] With reference to FIG. 2, a second flow chart is showed
which comprises the flow chart of FIG. 1, but it introduces some
new logical and operating blocks.--
[0097] The blocks of FIG. 2 having the same functions of the blocks
of FIG. 1 are here numbered with the same numbers from 1 to 11; the
new blocks are here numbered from 21 to 29 (however some numbers
are missing).--
[0098] Moreover the new blocks are easily recognized as their
external perimeter is highlighted with a double line.--
[0099] Now the meanings of the main blocks that have been added is
explained shortly, as the reasons of their presence and the related
working modes is easily guessed and understood by the man skilled
in the art.--
[0100] Block 21. After the checks in the previous blocks 6 and 7,
this operation assures the restoring of the speed condition that is
the same as in the block 2, i.e. wherein the laundry load is fully
distributed on the inner drum wall; it is a mandatory condition for
the spinning phase.--
[0101] Block 29. t<t.sub.M: it means that each time the
recalculation loop addresses back to block 5, a check of the
operating mode is done to verify that the total execution of the
program is not longer than a maximum pre-defined time interval; as
a matter of fact it can happen that, observing FIG. 1, the washing
machine (or washing-dryer machine) is never launched into spinning
but it goes on working endless according to the closed loop
5-6-9-10, or 12-11-5.--
[0102] Block 27 and 27A. .omega..ltoreq..omega..sub.MINd: it means
that, should the speed attained by the foreseen deceleration be
lower than a minimum pre-defined limit, then the reestablishment to
said minimum speed .omega..sub.MINd is determined.--
[0103] Block 28 and 28A. .omega..ltoreq..omega..sub.MAXd: it means
that, should the speed attained by the foreseen deceleration be
higher than a maximum pre-defined limit, then the reestablishment
to said maximum speed .omega..sub.MAXd is determined.--
[0104] Block 23. It is checked whether the drum speed is the same
drum speed .omega..sub.MAIN in block 2; it is used as a preparatory
phase of the spanning phase, and in this phase the drum speed must
be such to allow the complete distribution of the laundry load on
the inner drum wall.--
[0105] Block 24. This block too is a check phase before spinning;
it is verified that in the preliminary phase the unbalance mass be
low enough. It can be considered a repetition of the verification
of block 6, but as a matter of facts the latter is an absolutely
needed check to implement the instant invention, as the check in
block 24 is an operation intended to increase the confidence for a
correct operation. There is no need to check here that the amount
of the elevation torque be low enough as, at the present speed, the
laundry load is practically retained by the drum wall.
[0106] Block 25. It is a counting register; it counts number of
times the check in block 24 has given a consent for spinning. As to
the sampling frequency of the measurements, and so of the checks
done, it may advantageously be around 50 times/sec. If said checks
are performed for instance N=10 times as represented, it turns out
that only 0.2 seconds are requested to verify, with a reliable
number of times, that all the given conditions, i.e. the load
balance, the laundry distribution and the drum speed are suitable
to start the drum into spinning.--
[0107] With reference to FIG. 3, the behaviour of the various
parameters measured and calculated in an actual working cycle can
be observed; it has to be precisely noticed that the drum actual
speed follows very closely the target speed, that to its turn shows
a saw-tooth profile, being the speed determined by the cited
iterative process of acceleration/deceleration that is continuously
implemented and updated (within maximum time limits that have been
already explained), according to what determined in the blocks 10
and 12.--
[0108] It is then apparent that the instantaneous speed basically
follows the progress of said target speed, as it is the latter
which controls the time by time motor working.
[0109] Moreover it is to be noticed that at a certain time, T in
the diagram, the actual speed tends to increase beyond its previous
average amounts; in the facts at this time the spinning phase is
started, as the two conditions 1 and 2, previously described, have
been met.
[0110] It can be immediately verified that, at that time, the
unbalance mass m takes its minimum amount and, in the same time,
the elevation torque takes its minimum amount, in its absolute
value.--
* * * * *