[0001] The present invention relates to a method to control a laundry apparatus.
[0002] Commonly, a washing machine includes a tub where water is introduced, a drum which
is rotatably mounted inside the tub to receive laundry, such as clothes, shoes, accessories
etc., and a motor which generates a drive force to rotate the drum, thereby allowing
washing to be performed via tumbling of laundry in the drum. For example, the laundry
is tumbled along an inner wall of the drum during rotation of the drum.
[0003] Further, in such washing machines, a plurality of washing programs or drying programs
are generally available. Commonly, washing programs or cycles include a washing step
to eliminate stains on laundry using water and preferably also a detergent, and a
rinsing step to rinse the laundry.
[0004] The weight of the load which is introduced in a washing machine, that is, the weight
of the laundry introduced in a drum of a washing machine, is a relevant parameter
for the correct operations of the washing machine in a washing program. The weight
of the laundry indeed may determine the correct amount of water and/or detergent which
needs to be introduced inside the tub or drum during a washing step or the speed at
which the drum should be rotated in order to wash the laundry properly or not to create
imbalances and noises. Further, it may influence the overall duration time of the
washing program.
[0005] On the other side, weighting the laundry with a weighting scale or the like is not
a feasible step to be achieved in a washing machine, due to its construction and the
presence of water. Further, the weighting of the laundry should not increase the costs
of production of the washing machine in such a way that it may change the overall
apparatus cost noticeably.
[0006] There is a need of a method to control a washing machine, and a washing machine in
which the weight determination is rather easy, realized in a relatively quick way
and performed only when needed.
[0007] For this purpose, some methods have been developed by the same Applicant, where,
in order to determine the load at the beginning of the washing program, some initial
tumbling or spinning of the drum is required for a limited amount of time. In some
particular conditions, such as when the washing machine has been fully loaded, and/or
the laundry has not been optimally loaded, etc., during the execution of the tumbling/spinning
sporadic cases of motor alarms or hits between the drum or tub or components attached
to any of those and the cabinet might happen.
[0008] It is therefore desired to avoid such situations, in particular to avoid or minimize
motor alarms (due to too high torque requested to the motor), hits between the washing
group and the cabinet (due for example by a laundry ball "trapped" between the bellows
and the glass porthole) or excessive rubbing of the laundry.
[0009] EP 2 684 990 discloses a laundry treating appliance for treating a laundry load according to at
least one cycle of operation and a method of operating a laundry treating appliance
to determine an amount of imbalance of the laundry load in the drum based on a determined
average peak-to-peak value and taking corrective action when the determined amount
of imbalance does not satisfy a threshold.
[0010] According to an aspect, the invention relates to a method for operation of a laundry
apparatus, said laundry apparatus including a drum which is rotatably mounted in a
casing, the method including:
∘ selecting a washing or drying program among a plurality of washing or drying programs;
∘ rotating the drum for a given first time interval and given first speed before beginning
of said selected washing or drying program;
∘ calculating a value associated with a torque and/or an unbalance of the drum during
the rotation at the first speed;
∘ comparing the value with a first and/or second threshold;
∘ if said value associated with a torque and/or an unbalance is above the first and/or
second threshold, then the method further includes:
- emitting a command to change a parameter of said selected washing or drying program;
or
∘ if said value associated with a torque and/or an unbalance is below or equal to
the first and/or second threshold, then the method further includes:
- calculating a first weight of laundry present in the drum before beginning of said
selected washing or drying program.
[0011] In the present context, a laundry apparatus includes both washing machine and laundry
dryers. A washing machine may indicate a "simple" washing machine where the washing
of laundry is performed, or a combined washer dryer, where, in addition to the washing,
drying of the laundry is performed.
[0012] The laundry apparatus includes a drum where laundry is located, which can rotate
around an axis by means of a motor. The axis of rotation of the drum can be horizontal,
that is, substantially parallel to a surface where the appliance is located or slightly
tilted to it, or vertical. Therefore, the laundry apparatus might be a front loading
laundry apparatus or a top loading laundry apparatus as well.
[0013] The laundry apparatus further preferably comprises a casing, preferably but not necessarily
parallelepiped-shaped, on which a door is advantageously hinged to access and close
the drum in order to load or unload the laundry to be washed and/or dried. The door
is preferably hinged on a front wall of the casing in case of a front loading laundry
apparatus, while it is hinged on a top wall of the casing in case of a top loading
laundry apparatus.
[0014] Further, in case the laundry apparatus is a washing machine, the latter is connected
to a water supply, for example to the water mains, by means of suitable pipes which
can be opened or closed, for example by a valve, in order to introduce water to the
drum. One or more discharge pipes can be present as well in order to discharge water
from the drum.
[0015] A drawer or other container is also preferably present and fluidly connected to the
drum in order to introduce detergent into the drum itself, if needed during the laundry
washing.
[0016] A condensate canister may be present as well to collect the water condensed during
drying.
[0017] The laundry apparatus may further include a control panel, for example located in
an upper portion of the casing, where inputs or commands can be selected by an user,
and/or information about the status of the laundry apparatus can be displayed, for
example by means of a display or one or more light indicators.
[0018] In operation, a laundry apparatus include a plurality of washing or drying programs.
In case of a washing program, each washing program preferably includes a washing step
where the laundry is washed, such as tumbled, and a rinsing step, where the laundry
is rinsed. The washing program may also include a spinning step where the drum is
rotated at relatively high velocity. Further steps may be present as well, for example
a pre-washing or others. In case of washing and drying program, a drying step is added
at the end of the spinning. In case of purely drying programs, different steps at
different drying temperatures might be present, dividing the laundry program in different
time intervals, where the speed of the drum might also be varied.
[0019] The various washing or drying programs may differ one from the others for the duration
of the same, for the number or rinsing steps, for the temperature of the washing water,
for the amount of detergent, the drying temperature, the rotational speed of the drum
and so on.
[0020] The washing or drying programs are preferably designed to treat laundry made of a
specific textile type or composition or type of dirt or stain. For example, in a washing
machine, a cotton program at high temperature is generally present, as well as a delicate
program for delicate textiles (e.g. silk) at lower temperatures. The same applies
to a drying machine, where the drying temperature for cotton is different from the
drying temperature for synthetic textiles.
[0021] According to the invention, a washing or drying program is set. The washing program
or drying program is generally set either by a user operating on the control panel,
for example by means of a switch, button, knobs and the like, or automatically, that
is, a predefined washing program is stored on a memory of the laundry apparatus and
automatically selected when the appliance is switched on. Alternatively, the laundry
apparatus may "auto-select" the washing program among the available ones, for example
all stored in a memory, depending on one or more characteristics of the laundry inserted
in the drum, which are automatically detected.
[0022] The setting of a washing or drying program predefines one or more of a plurality
of parameters, that is, given the washing or drying program, for example the duration
of the same may be defined, as well as the type and quantity of detergent to be used,
the temperature of the water, the amount of water to be used in washing, the amount
of water to be used in rinsing, the revolution per minute of the drum, the maximum
allowed weight of the laundry, and others.
[0023] In addition, for some or all washing or drying programs, some constraints on the
program may be present. For example, in case a synthetic program has been selected,
it is not allowed to select a high washing temperature (for example a temperature
above 60°C). If a delicate program has been selected, a load above a certain threshold
cannot be selected at the same time. Those constraints are imposed to avoid a poor
performance of the selected washing or drying program. However, the user may be allowed
to override some of those constraints, for example inputting specific commands on
the control panel.
[0024] According to the invention, before the beginning of the washing or drying program
which has been set, a check is performed on the loading of the drum. In other words,
the drum is rotated for a given first time interval and at a given first speed. This
rotation is performed before the beginning of any washing or drying program, for example,
in case of a washing program, before water is introduced in said drum. This rotation
for a limited time interval can be performed at a rather "high" speed, such as 80
rpm.
[0025] During this rotation at the first speed, a value associated with a torque and/or
an unbalance of the drum is calculated. For example, this value can be the mean torque
or the mean unbalance of the drum during a certain time interval. For example, the
mean torque or the mean unbalance during the whole first time interval can be calculated.
[0026] Preferably, the apparatus includes a motor control unit, which senses signals from
or characteristics of the functioning of motor. The torque can be for example calculated
by the motor control unit which senses characteristics of the electric current absorbed
by the motor. The torque calculated by the motor control unit can be for example an
average torque calculated over two complete rotations of the drum around its axis.
[0027] The unbalance is also calculated preferably by the motor control unit. The clauclation
can be performed sensing characteristics of the electrical current absorbed by the
motor over two complete rotations of the drum around its axis.
[0028] Further, preferably, the value of torque and/or unbalance calculated or obtained
by the motor control unit, is sent to a main control unit of the apparatus to be possibly
further elaborated.
[0029] Rotating unbalance is the uneven distribution of mass around an axis of rotation.
A rotating mass, such as the rotating drum of the apparatus, is said to be out of
balance when its center of mass (inertia axis) is out of alignment with the center
of rotation (geometric axis). Unbalance causes a moment which gives the drum a wobbling
movement characteristic of vibration of rotating structures.
[0030] This calculation is performed to detect whether the load is correctly placed within
the drum, whether there are unbalances present, whether there is an overload of the
drum, etc. This step is preferably performed before starting any other process in
the apparatus, because detecting an excessive torque or an excessive unbalance at
the beginning of the apparatus functioning avoids or minimizes triggering any alarm
response.
[0031] In order to determine whether the value representing the torque and/or the unbalance
is indicating a potentially problematic condition, this value is compared with a first
and/or a second threshold. For example a torque threshold T1 and an unbalance threshold
T1' are set. According to the invention, two values might be calculated, i.e. a value
representing the torque and a value representing the unbalance, or only one of these.
Further, both or only one of these values can be compared with a threshold, T1 and/or
T1'.
[0032] The result of the above mentioned comparison triggers a different response. If said
value associated with a torque and/or an unbalance is above the first and/or second
threshold, that is if the first value relative to the torque is > T1 and/or if the
value relative to the unbalance is > T1', then the method further includes a step
of emitting a command to change a parameter of said washing program.
[0033] If the torque and/or unbalance is "high", it means that there is either excessive
load in the drum or the laundry is not correctly positioned within the drum. Therefore,
in order to perform a correct washing or drying program, a command is sent - for example
by the main control circuit of the apparatus - which forces the selected washing or
drying program to consider this situation. The situation is considered forcing the
change of a parameter of the selected washing or drying program.
[0034] Depending on the apparatus, it might be enough that only one value is above T1 or
T1' or it is needed that both values (related to torque and unbalance) are above their
respective threshold. Further, there is no need that both values are compared with
their respective threshold. A single comparison may be enough.
[0035] For example, the command might include "set the load equal to the maximum load accepted
by the apparatus". In this case, the apparatus during the washing or drying program
considers that the drum has been loaded with the maximum possible weight of laundry.
[0036] The maximum load may depend on the type of laundry apparatus, because not all laundry
apparatuses have the same maximum load. Commonly, laundry apparatuses having a maximum
load of 5 kg, 8 kg or 4 kg are known for household uses.
[0037] It has to be understood that not all washing or drying programs allow this change:
there are programs where, for the correct execution of the program itself, it is not
possible to select as the load the maximum load accepted by the laundry apparatus.
[0038] Further, it is possible that the maximum load has been already selected by the user.
In this case, the command does not change any parameter in the washing or drying program,
because this parameter is already set as required by the circumstances.
[0039] Therefore, in these examples, the command to change the parameter is sent, but it
does not have any "visible" consequence.
[0040] Preferably, if the torque and/or unbalance is "high" (as defined above), then there
is no calculation of the weight of the laundry before the beginning of the selected
washing or drying program.
[0041] If said value associated with a torque and/or an unbalance is "low", that is, if
this value is below or equal to the first and/or second threshold T1, T1', then a
"standard" situation is present and the method further includes the step of calculating
a first weight of said laundry before beginning said selected washing or drying program.
[0042] Therefore, when the situation is not "problematic", because the value related to
the torque and/or the value related to the unbalance are below their respective threshold
T1 and T1', then a weight of the laundry is calculated before the selected washing
or drying program starts.
[0043] Depending on the apparatus, it might be enough that only one value is below T1 or
T1' or it is needed that both values (related to torque and unbalance) are below their
respective threshold. Further, there is no need that both values are compared with
their respective threshold. A single comparison may be enough.
[0044] Thus, in case of "low" torque or unbalance, the calculation of a first weight of
the laundry introduced into the drum is performed. Such calculation takes place in
any known manner, by means of a first weight sensor.
[0045] For example, the first weight sensor may be a mechanical sensor of the weight of
the laundry, but it may also be a predictive algorithm calculating the first weight
by statistical methods. This first weight calculation determines a certain value of
the weight of the laundry introduced in the drum. This first weight may be compared
with a first weight threshold.
[0046] Preferably, the calculation of the first weight is relatively "rough", that is, with
a relatively low precision, and performed in a rather fast manner.
[0047] According to the invention, therefore, a first weight calculation is performed only
when the risk of triggering an alarm due to a too high torque or unbalance is relatively
low. In case a high unbalance or torque, the selected washing or drying program is
"adjusted" to take the situation into consideration, altering a parameter of the same,
such as the load.
[0048] According to the aforementioned aspect, the invention may include one or more of
the following characteristics.
[0049] Preferably, calculating a first weight of said laundry before the beginning of said
selected washing program includes calculating a weight of said laundry before water
is introduced in said drum.
[0050] In case of a washing machine, the measurement of the first weight of the laundry,
in case of a low torque or unbalance, is performed before the beginning of the selected
washing program, which means before the introduction of water into the drum or the
tub. The first calculation is preferably a fast calculation.
[0051] Preferably, emitting a command to change a parameter of said selected washing or
drying program includes changing a load setting of the washing program equal to a
maximum load accepted by the laundry apparatus.
[0052] In order to take into account the fact that there is a high torque or unbalance in
the drum, the load is set to the maximum possible one. The selected washing or drying
program is therefore performed as if in the drum there is the maximum acceptable load
for the apparatus (regardless of the real load present). The maximum load value depends
on the type of apparatus, e.g. it can be for example 5 or 8 kilos in case of household
apparatuses.
[0053] Preferably, emitting a command to change a parameter of said selected washing or
drying program includes emitting a warning signal. More preferably, emitting said
warning signal includes emitting said warning signal if said parameter change is not
allowed by the selected washing or drying program. Even more preferably, emitting
said warning signal includes emitting said warning signal if said selected washing
or drying program does not allow a load setting equal to the maximum load accepted
by the laundry apparatus.
[0054] As mentioned, washing or drying programs may have constraints in the range of parameters
which can be set. These constraints are present in order to perform the washing or
drying programs correctly and obtain a proper result, without damaging the laundry
introduced in the drum. For this reason, it is not always possible to fulfil the command
request, that is, although a command signal has been sent to change a parameter of
the selected washing or drying program, the selected program does not allow such a
change. For example, if the requested change via the command is to put load = "maximum
load of the apparatus" in a delicate program, the program itself via a control unit
will refuse to perform such a change because a delicate program does not allow to
have a heavy load. In this case, therefore, a warning signal is emitted, to warn the
user of this problem. As an example an "overload" indication can be emitted.
[0055] Preferably, in this case where a warning signal is emitted, the program is forced
to set the load equal to the maximum load possible for that specific program (which
- as said - can be different from the maximum load accepted by the apparatus).
[0056] Preferably, the method includes calculating a second weight of said laundry after
beginning of said selected washing or drying program. More preferably, calculating
a second weight of said laundry after beginning of said selected washing program includes
calculating a second weight of said laundry during/after water has been introduced
in said drum.
[0057] This second weight is calculated after the selected washing or drying program has
started, for example after water has been introduced into the tub and/or drum, or
during the introduction of the water itself. This second weigh calculation is "the
second one" only if the first weight calculation has been performed, that is, preferably
only if the torque and/or balance have been found "low".
[0058] In this second calculation, the weight of the laundry is calculated again, for example
preferably in a longer and/or more precise manner. This second weight calculation
can be used to vary other parameters of the selected washing or drying program, for
example its time to end.
[0059] Preferably, the method includes calculating a time to end of said selected washing
or drying program before the step of calculating the value associated with a torque
and/or an unbalance.
[0060] It is known that a user prefers to receive information about the status of the washing
program. One of these desired information is the duration of the washing program.
So, a first estimate of the time to end is visualized to the user, for example by
means of a display, on the basis of the selected washing or drying program only.
[0061] Preferably, the method includes updating said time to end after emitting a command
to change a parameter of said selected washing or drying program or after calculating
said first weight before the beginning of said selected washing or drying program.
[0062] The time to end depends on the parameters of the selected washing or drying program.
Due to the fact that the command modifies a parameter of the washing program, the
time to end may be affected as well and therefore an update is preferred.
[0063] Further, the time to end may be affected by the weight of the laundry in the drum.
Therefore, after the first weight calculation, the time to end may need to be updated
as well.
[0064] Preferably, the step of calculating the weight of said laundry before the beginning
of said selected washing or drying program includes rotating and stopping the rotation
of said drum a plurality of times.
[0065] The first weight calculation may include a plurality, e.g. in the number of four,
of "bursts" of rotation of the drum. Preferably, in these rotation, the drum is rotated
for a short time at a given speed (e.g. between 30 rpm and 80 rpm) and then stopped.
The given speed may be preferably equal to the first speed.
[0066] In these bursts, parameters of the motor and/or the drum are calculated in order
to obtain a weight calculation.
[0067] Preferably, said apparatus includes a motor driving the drum in rotation and calculating
a first weight of the laundry in the drum before the beginning of the selected washing
or drying program includes:
o calculating the first weight by detecting one or more parameters of the motor while
the drum is rotating.
[0068] The drum is rotated by means of a motor, which may also control the drum velocity
and the reversal of rotations, if needed. In order to calculate the first weight,
which is calculated without the introduction of water into the drum, preferably parameters
of the motor while it rotates the drum are calculated, for example sensed or detected
by suitable sensor(s) which are commonly present in a washing machine for other purposes.
One of these parameters can be for example the torque of the motor. However, one or
more of the following can be used as well:
- Parameters indicative of the operating conditions of the motor driving the drum in
rotation, such as a motor torque value and/or a power absorbed by the motor and/or
a current absorbed by the motor;
- Speed or acceleration of the drum or number of times in which the drum reverses its
rotation direction;
- Speed or acceleration of an agitator located in the drum to move the laundry located
therein;
- Humidity of the laundry and variations thereof;
- Time from the beginning of the selected program and/or phase of the program which
is taking place;
- Parameters indicative of operating conditions of mechanical elements of the appliance,
like the opening or closing of valves, the activations of alarms and so on;
- Etc.
[0069] Preferably, said apparatus includes a motor driving the drum in rotation and calculating
a first weight of the laundry in the drum before beginning of the selected washing
or drying program includes:
- Sensing a plurality of parameters concerning operating conditions of the washing machine;
and
- Predicting a weight of the laundry present within the washing machine based on said
plurality of parameters by means of a data-driven soft sensor.
[0070] The weight of the laundry in a laundry treatment appliance is a quantity that is
either unmeasurable or costly/time-consuming to obtain. Therefore, in the present
invention a statistical model-based technology addressed to industrial environments
that provide an estimate of such quantity is used. The primary purpose of sensors
is to deliver data for process monitoring and control. In the context of process industry,
predictive models are called Soft Sensors: term is a combination of the words "software",
because the models are usually - but not necessarily - computer programs, and "sensors",
because the models are delivering similar information as their hardware counterparts.
Other common terms for predictive sensors in the process industry are inferential
sensors, virtual sensor or on- line analyser and observer-based sensors.
[0071] Two different classes of Soft Sensors, namely model-driven and data-driven, can be
distinguished.
[0072] Model-driven models are also called white-box models because they have full phenomenological
knowledge about the process background. In contrast to this purely, data-driven models
are called black-box techniques because the model itself has no knowledge about the
process and is based on empirical observations of the process. In between the two
extremes there are many combinations of these two major types of models possible.
A typical example of such a combination is a model-driven Soft Sensor making use of
data- driven method for the modelling of fractions which can not be modelled easily
in terms of phenomenological models.
[0073] The present invention preferably uses a data driven model, being based on empirical
data. Therefore a data-driven soft sensor is an inferential statistical model developed
from process observations.
[0074] The soft sensor, which normally operates using a software, might be embedded in the
control unit of the appliance. The same control unit - as already stated - preferably
controls also the appliance during its functioning, that is, during the execution
of the selected laundry program, for example sending command signals to the motor
of the drum and to the other components participating in the correct functioning of
the appliance. For example, in a heat pump dryer, the control unit sends command signals
to the heat pump.
[0075] In this way, making use of values from sensors which are already available in the
appliance for other purposes, and the same processor already used to control the proper
functioning of the appliance, the weight of the laundry introduced inside the washing
machine is predicted. This prediction is obtained by means of a statistical method
by means of a soft sensor which is data driven. The operation of "training" the soft
sensor is preferably performed in the production site. Without adding further elements
(such as a new sensor) to the appliance, a prediction of the weight of the laundry
is obtained.
[0076] Preferably, said step of predicting a first weight of the laundry by means of a data
driven soft sensor includes a step of predicting a first weight of the laundry by
means of a supervised learning prediction.
[0077] In supervised learning, from input data (in this case the values of the operating
conditions of the appliance) are used to predict an output value (in this case the
weight of the laundry).
[0078] In supervised learning, input data is called training data. A model is prepared through
a training process where it is required to make predictions and is corrected when
those predictions are wrong. The training process continues until the model achieves
a desired level of accuracy on the training data. Preferably, the soft sensor of the
invention uses a supervised learning method, that is a learning task of inferring
a function from labelled training data. The training data consist of a set of training
examples. In supervised learning, each example is a pair consisting of an input object
(typically a vector) and a desired output value (also called the supervisory signal).
A supervised learning algorithm analyses the training data and produces an inferred
function, which can be used for mapping new examples.
[0079] In the present invention therefore, preferably the soft sensor uses the operating
conditions of the appliance during the selected program and the output value includes
the weight of the laundry present in the drum of the laundry treatment appliance.
This is done after the algorithm had been properly trained by the training examples
which are data collected in field tests of the appliance.
[0080] Preferably, the method includes performing said selected washing or drying program
after said first weight calculation and/or after emission of said command.
[0081] The washing or drying program then can start, either modified by the command or as
selected by the user.
[0082] Preferably, said laundry apparatus includes a display and/or a light indicator and
said step of emitting a warning signal includes displaying a warning message on the
display or switching on the light indicator.
[0083] It is known that a user prefers to receive information about the status of the washing
or drying program. In addition, if a possible problematic situation may arise during
the washing or drying program, it is preferred to inform the user, so that he/she
can take action. Thus, such information as the warning signal is visualized to the
user, for example by means of a display or any light indicator (e.g. LED on the control
panel).
[0084] Preferably, the method includes waiting for or requesting an external input after
emitting a command or calculating said first weight before beginning of said selected
washing or drying program.
[0085] As seen, after emitting said command, a warning signal might be present. Alternatively,
an indication that the load has been changed into the maximum load allowed by the
apparatus may be emitted as well. It is preferred that the user is informed of the
status of the apparatus (e.g. torque and/or unbalance above a threshold), and that
he/she is allowed to modify the status of the apparatus itself, for example by removing
some laundry from the drum, by reshuffling of the laundry in the drum or even by changing
the selected washing or drying program. For this purpose, preferably a waiting time
is allotted. During this waiting time, the user may open the door of the apparatus
and operate in the drum.
[0086] Alternatively, there is no information given by the apparatus of the request for
input. That is to say, the method of the invention might provide for a time interval
during which the apparatus allows the user to modify some of its settings, such as
the amount of load in the drum or its distribution, without warning or requesting
it visibly.
[0087] Further, also at the end of the calculation of the first weight, information for
the user can be displayed, for example in case of a too high or too low weight of
the laundry present in the drum. Therefore, there should be preferably the possibility
for the user to alter the status and change for example the amount of load present
in the drum, adding or removing laundry or redistributing the content of the drum.
[0088] Preferably, the method includes:
o comparing said first weight with a third threshold; and
o requesting an external input if said first weight is above or below said third threshold.
[0089] When the first weight is calculated, which happens when the torque or the unbalance
is "low", then the first weight can be compared to a third threshold, such as value
T2, so that it is checked whether a different problematic condition may arise. For
example, in case the weight of the laundry is too high or too low for the selected
washing or drying program, the selected washing or drying program may not give the
expected results. To avoid this, the user may change the condition of the drum, adding
or removing laundry for example, in the same waiting time interval which is available
after the calculation of the first weight.
[0090] Preferably, the method includes, in case said external input is received, rotating
said drum for a given second speed.
[0091] In case the external input is received, that is, the user has opened the door of
the apparatus and made some adjustments to the laundry contained in the drum (removing
laundry, adding laundry, reshuffling the same, etc.), some movements to disentangle
the laundry are performed, Preferably the rotational speed of the drum in these movements
is lower than the first speed, that is, second speed < first speed.
[0092] Preferably, the method includes, after receiving said external input, rotating the
drum for a given first time interval and given first speed before beginning of said
selected washing or drying program; and calculating a value associated with a torque
and/or an unbalance of the drum during the rotation at the first speed.
[0093] The method may include a step in which some untangling movements of the drum are
provided for. During this untangling movements, preferably at a second speed lower
than the first speed (e.g. at a second speed of about 40 rpm for 2 seconds), the laundry
is shuffled around in the drum. After the untangling movements, the calculation of
the torque and/or the unbalance is performed again and its evaluation (i.e. the comparison
with the corresponding threshold) is made. The method is repeated from the beginning.
These untangling movements are performed preferably only if an external input is received,
e.g. if the user opens the door of the apparatus.
[0094] Alternatively, there are no untangling movements and, after the input of the user,
the method of the invention starts again, calculating the value associated with the
torque and/or the unbalance and repeating the comparison with the thresholds.
[0095] Preferably, the method comprises, in case said external input is not received, starting
said selected washing or drying program.
[0096] In case nothing happens, that is, in case no input is received from the user, the
program which has been selected can start.
[0097] Preferably, the step to calculate a value associated with an unbalance includes calculating
a value associated with a static unbalance of the drum.
[0098] A static unbalance is defined as a single mass placed in the center of the drum (center
of gravity). Rotating the drum, the static unbalance generates a centrifugal force
that causes an undesired translational movement (cylindrical) of the washing group
and high level of vibrations. An excessive static unbalance can cause mechanical damages.
[0099] A static unbalance occurs when the inertial axis of a rotating mass is displaced
from and parallel to the axis of rotation. It is calculated as:

where U = Unbalance, m = mass, r = distance between unbalance and the centre of the
object.
[0100] Preferably, said first weight calculation lasts less than 1 minute.
[0101] The first weigh calculation is preferably "rough" but very fast in order to start
the washing or drying program without delay.
[0102] Preferably, calculating the second weight includes:
∘ checking a level of water inside the drum; and
∘ calculating a second weight of the laundry present into the drum on the basis of
the amount of water needed to maintain a pre-set level of water in the drum.
[0103] The second weight calculation is preferably an accurate calculation, that is, preferably
more accurate than the first calculation, and also it may last longer than the first
calculation in order to obtain the second weight value. The second calculation is
performed after the water has been allowed into the drum, for example via an inlet
pipe, and it uses the amount of water introduced as an indicator of the weight of
the laundry. The level of the water in the drum is thus checked as a measure of the
amount of water in it and of the amount of water absorbed by the laundry. The variations
of the water level due to the absorbance of the water introduced in the drum by the
laundry are monitored and when these variations remain below a certain value, that
is, when these variations are "small", then the second weight is calculated.
[0104] Preferably, calculating the second weight includes:
∘ introducing in the drum a pre-determined amount of water;
∘ waiting a predetermined time interval;
∘ stopping water introduction if after said predetermined time interval a water level
variation within said predetermined time interval is below or equal to a third threshold;
∘ calculating a second weight of the laundry present into the drum on the basis of
the amount of water added in the drum up to the stopping of water introduction.
[0105] In order to calculate the second weight, preferably a predefined amount of water
is introduced in the drum. This amount is predefined and preferably depends on the
set washing program. After the water introduction, the water level in the drum is
checked, it is waited for a given time interval and after this time interval has elapsed,
the level of water in the drum is checked again. A variation of the water level can
be thus calculated, subtracting from the initial water level the end water level.
If the laundry has absorbed so much water that the variation of the water level is
above a third threshold, more water is introduced, again in a pre-defined amount,
and the steps above are repeated, to check whether the water level variations are
still "big", i.e. above the third threshold limit. As above, the water level may be
monitored with or without drum rotations.
[0106] The time interval is set so that generally the laundry has absorbed all the water
it can absorb within it, so that the level of water into the drum cannot get lower
than a given value even if more time than the pre-set one elapses. In this way, the
second weight can be determined on the basis of the amount of water absorbed by the
laundry.
[0107] Preferably, calculating a first weight of laundry present in the drum before beginning
of said selected washing or drying program includes:
∘ determining a first duration of said selected washing program on the basis of said
first weight;
∘ displaying said first duration on a display.
[0108] Preferably, the first duration is updated on the basis of the second weight. Updating
said parameter on the basis of said second weight includes:
∘ determining a second duration of said set washing program on the basis of said second
weight;
∘ updating said display displaying said second duration.
[0109] Due to the fact that the first weight calculation is performed rather fast, while
the second weight calculation is relatively slow, in order to give immediately some
feedback to the user, some parameters of the washing program are already calculated
just after the first weight calculation and for example displayed. One of such parameters
could be for example the duration of the washing program. When the more accurate weight
calculation is obtained so that the value of the second weight is available, then
the parameter is updated so that the user can see the correct parameter and rely on
it.
[0110] The update could also result in keeping the parameter equal to what it had been determined
using the first weight. For example, the duration calculated using the first weight
could be identical to the duration calculated using the second weight.
[0111] The present invention will now be described with reference to the accompanying drawings
that illustrate non-limiting embodiments thereof, wherein:
- Fig. 1 is a isometric view of the washing machine of the invention;
- Fig. 2 is a further isometric view of the washing machine of figure 1 with the casing
made transparent in order to show its inner components;
- Fig. 3 is an isometric view of the washing machine of figure 2;
- Fig. 4 is a flow chart of the various steps of the method of the invention; and
- Fig. 5 is a graph of several values relevant in the method of the invention.
[0112] The following description refers to an advantageous embodiment of the invention in
which the washing machine 1 is a "standard washing machine" with no drying functionality
(i.e. a washing machine which can only wash and rinse the laundry).
[0113] However it is clear that the invention can be applied as well to washer - dryers
(i.e. a washing machine which can also dry the laundry), not illustrated. Further,
although this preferred embodiment is limited to washing machine, the invention applies
to laundry dryers as well.
[0114] The washing machine 1 according to the invention which is schematically illustrated
in the enclosed Figures is advantageously of the front-loading type; it is however
clear that the invention is applicable, substantially without any crucial modification,
to a top-loading washing machine.
[0115] With reference to Figures 1 to 3, the washing machine 1 comprises an external casing
2 in which frontal wall 2a an access opening 3 is obtained, provided with a loading/unloading
door 4, which allows the access to a washing tub 5 contained in the external casing
2; the washing tub 5 contains a rotatable perforated drum 6 in which the laundry to
be washed, not depicted in the drawings, can be loaded and unloaded. In this advantageous
embodiment the drum 6 embodies, therefore, a treating chamber in which one or more
items (pieces of laundry in this advantageous embodiment) can be loaded and treated
with water and one or more additives (washing/rinsing products in this advantageous
embodiment). The rotational axis of the drum 6 is substantially horizontal.
[0116] The washing tub 5 is connected to the external casing 2 preferably via a flexible
bellows, not represented, connected between the frontal, opened, surface of the washing
tub 5 facing the access opening 3, and the border of the latter.
[0117] In the example illustrated, the washing tub 5 is advantageously elastically supported
by the external casing 2 via a suitable resilient support system, comprising, for
example, springs 8; preferably the oscillations of the washing tub 5 are damped by
suitable shock-absorbing devices or dampers 9, interposed between the washing tub
5 and the bottom of the casing 2.
[0118] Clearly, the washing tub 5 may be associated to the casing 2 in any other suitable
way.
[0119] Advantageously, the washing machine 1 comprises a water inlet circuit, not visible
in the figures, adapted for feeding water and washing/rinsing products, into the washing
tub 5; the water inlet circuit comprises, for example, a removable drawer 19, adapted
to be filled with washing and/or rinsing products, e.g. liquid or concentrate or gel
detergent, or powder detergent, or softener, an inlet duct, also not represented,
connectable to water delivery means present outside the washing machine 1 and adapted
to deliver fresh water to the drawer 19 and/or to the tub, and an outlet duct, fluidly
connecting the drawer 19 and the washing tub 5 and adapted to deliver water and washing/rinsing
products into the washing tub 5.
[0120] The washing machine 1 also advantageously comprise a draining circuit, fluidly connected
to the bottom of the washing tub 5 and adapted to drain the washing/rinsing liquid
from the washing tub 5; in a further embodiment, not illustrated, the draining circuit
may be also provided with a recirculation circuit, adapted to drain the washing/rinsing
liquid from the bottom of the washing tub 5, and to re-admit such liquid into an upper
region of the washing tub 5, for improving the wetting of the laundry.
[0121] Water inlet circuit and draining circuit are considered standard and known in the
art and therefore not further discussed.
[0122] The washing machine 1 also comprises some electric and/or electronic components,
adapted for performing some specific functions; for example the washing machine comprises
an electric motor 11 for rotating the rotatable drum 6, a valve (not shown) adapted
to deliver the washing/rinsing liquid into the washing tub 5, an electric pump (not
shown) adapted to drain and/or to recirculate the washing/rinsing liquid from the
washing tub 5, an electric heater (also not shown) adapted to heat the washing/rinsing
liquid, etc.
[0123] The drum 6 is advantageously rotated by the electric motor 11 which preferably transmits
the rotating motion from a motor shaft 24 to the drum 6, advantageously by means of
a belt/pulley system 29. In a different embodiment of the invention, the motor 11
can be directly associated with the shaft 24 of the drum 6.
[0124] The washing machine 1 advantageously comprises a logic unit (for example an electronic
board, a microcontroller, a microprocessor, or any other similar electronic control
unit/device), schematically indicated in Figure 1 with the block numbered 12, configured
to control the electric and/or electronic components of the washing machine 1, so
as to make the washing machine 1 to perform a washing program, advantageously comprising
one or more phases; for example the washing program may comprise a prewash phase,
a soaking phase, a main washing phase (comprising, for example, the adduction into
the washing tub 5 of water mixed with detergent and the rotation of the drum 6, so
as to apply a mechanical action on the laundry), a steam supplying phase, a rinsing
phase, a spinning phase, etc. The washing program may comprise one or more of the
above mentioned phases (or also other phases well known in the art) adapted to apply
to the laundry to be washed a specific chemical and/or physical action. A phase of
the washing program may be performed, during a single washing program, only once or
also two or more times. Clearly the duration of the overall washing program depends
on the kind, on the number, and on the duration of its phases.
[0125] Each washing program is defined by a plurality of parameters, which are for example
stored in a memory of the control unit 12. These parameters may include the duration
of the program, the water temperature during the main washing phase, the number of
rinsing phases, the maximum load for that specific program, and so on. Thus, when
a program among the plurality is set, a plurality of parameters is set as well.
[0126] Further, the washing machine 1 has a pre-defined maximum allowed load which can be
inserted in the drum. The maximum load depends on the model of washing machine. Some
programs may have as acceptable maximum load the maximum load of the washing machine,
other programs may have as maximum acceptable load a load lower than the maximum load
of the machine.
[0127] The washing machine 1 is also provided with a first weight sensor, schematically
represented in Figure 1 with the block numbered 13, which is configured to detect/measure
the weight of the laundry loaded in the rotatable drum 6. For example, the weight
sensor 13 may comprise one or more transducers, operatively connected to the logic
unit 12; the transducers may comprise, for example, a load cell or a strain gauge
and can be associated with the resilient support system 8, 9 supporting the washing
tub 5, as for example depicted in figure 2. More preferably, the first weight sensor
13 is a soft sensor measuring the weight of the laundry by means of an algorithm.
Most preferably, it is part of the control unit 12.
[0128] However, it is underlined that the use of a particular first weight sensor 13 is
not critical for the invention, and therefore substantially any device adapted to
measure the weight of the laundry loaded into the rotatable drum 6 may be used. In
all cases, the first weight sensor 13 is apt to measure a weight of the laundry when
the laundry is in a dry state, that is, before water is introduced inside the drum
6.
[0129] The washing machine 1 comprises a control panel or user interface 14, which is operatively
connected to the logic unit 12 and is configured to allow the user to manually set
a washing program to be performed. Alternatively, the washing program can be set automatically.
[0130] User interface 14 may comprise, for example, a touch screen display, adapted to display
information and to receive inputs from the user, and or it may comprise a one or more
buttons, and/or switches, and/or knobs, and/or displays, etc. allowing the user to
receive information and to input instructions/commands directed to the logic unit
12.
[0131] The user, by means of the user interface 14, may program the washing machine 1 with
one or more parameters indicating his/her "wish values" for them. That is, when the
washing program or program is set, the user may change some of the pre-memorized values
of these parameters by inputting its wished value from the user interface 14. These
user's inputs overrule the standard memorized values for the parameters.
[0132] User interface 14 may be further configured to display user information; this information
may comprise the name of a particular washing program, an indication of the weight
of the loaded laundry, the duration of the washing program, the temperature of the
washing/rinsing liquid, the rotating speed of the spinning, etc. More in general the
user interface 14 is designed to present information related to the washing program
and/or the status of the washing machine 1 and even more preferably it is designed
to display the duration of the washing program.
[0133] In the embodiment illustrated in the enclosed Figures, the user interface 14 advantageously
comprises a display device, preferably a LCD or a LED display, designed to present
user information, and a separated input device, not illustrated, comprising for example
a keyboard, and/or a set of keys or knobs, and/or one or more touch-sensitive input
devices, etc., adapted for setting a washing program and washing-product information.
[0134] In another embodiment, not illustrated, the logic unit 12 may be advantageously integrated
in the user interface 14.
[0135] Further, the washing machine includes a second weight sensor 16 apt to measure a
weight of the laundry in the wet state. As for the first weight sensor, this second
weight sensor 16 can be any as long as is apt to measure the weight of the laundry
when it is wet. This second weight sensor 16 can also be a soft sensor, that is, an
algorithm, and can be part of the logic unit 12, as depicted in figure 2.
[0136] A method of controlling the washing machine 1 will be described in more detail as
follows, with reference to figure 4. First, a washing program or program among the
stored plurality is set in the washing machine in step 1F. Such program or program
may be inputted by the user. Given the set washing program, a plurality of parameters
of the same is set, the values of which may be changed according to the method of
the invention. The user may also indicate a value of one or more of these parameters
of the washing program. For example, the user may push a button indicating that the
load of the laundry is the maximum load of the machine 1. Parameters relative to the
set washing program may be displayed on the display of the control panel 14, such
as for example the duration of the set washing program. The value displayed is either
the "standard" value, that is, the value as stored in the memory and considered to
be the default value for the set washing program, or the value of the parameter as
modified by the user. In case the parameter displayed is the duration of the program,
from this moment for example the countdown of the visualized value begins so at any
point in time the user is aware of the remaining duration of the washing program watching
the display of the user interface 14.
[0137] In step 2F, the drum 6 is rotated to a first speed for a first time interval. The
rotation of the drum at a first speed is depicted in the graph of Figure 5 (in this
graph, the units of the coordinate axes are arbitrary) as a curve indicated with v
representing the velocity of the drum (angular velocity or rpm).
[0138] Further, in step 3F, the unbalance and the torque as an average value of the torque
and unbalance during the first time interval are calculated. The resulting average
torque AT and average unbalance AU are also depicted in the graph of figure 5.
[0139] In step 4F, the average torque and/or the average unbalance are compared with their
respective thresholds, T1 and T1'. If any or both of the values of average torque/unbalance
is below the given threshold T1, T1', then the situation is "normal" and a "standard"
process starts.
[0140] Further, the weight of laundry is detected, before the water is introduced into the
drum, by means of the first weight sensor 13 in step 5F. For example, the first weight
value can be calculated driving the motor 11 to accelerate the drum 6 accommodating
laundry to a certain speed and then measuring the torque and using a predictive algorithm.
Therefore, from the measurement of the torque and/or imbalance at a first speed, the
speed of the drum is changed, for example lowered (see figure 5) and then accelerated
in order to perform the "burst". The drum is accelerated in bursts 100 as depicted
in figure 5. Parameters of these bursts are used to obtain a value of the first weight
of the laundry inside the drum.
[0141] The value of the first weight is used to calculate a parameter of the washing program,
for example the parameter visualized in the display of the user interface 14, for
example the duration of the washing program. In case the first weight calculation
gives a result which is already indicating that the parameter which has been visualized
after the selection of the washing program in phase 1F needs to be modified by the
new value calculated on the basis of the first weight, the value on the display can
be updated in phase 6F. The visualized parameter(s) therefore may have a "sudden jump"
from one value to the other, that is, from the pre-set memorized value that the set
program refers to in a memory of the washing machine, to a new value which is based
on the first weight value.
[0142] The first weight calculated in this step 5F may trigger also the display of alarms.
For example, the first weight could be above a given threshold and therefore a "overload"
indication may be displayed, or it might be too low.
[0143] Then, a waiting time interval is reached in step 7F. In this waiting time interval,
user intervention may take place, for example as a response of the warning message.
[0144] If in step 4F, any or both of the values of average torque/unbalance is above the
given threshold T1, T1', then the situation is "potentially nonstandard" and different
steps of the method of the invention take place. In this case, at the end of the calculation
of the torque and/or of the unbalance, the drum is stopped.
[0145] There is no measurement of the weight of the laundry in the drum before the beginning
of the selected washing program. The logic unit 12 sends a command to change the setting
of parameters of the selected washing program, for example changing the load therein
indicated with "maximum load allowed by the washing machine" in step 8F. If the washing
machine is for example an 8 kg washing machine, then the load to be considered in
the execution of the selected washing program is 8 kg. However, not all selected programs
allow having the load set equal to the maximum available load for the washing machine.
In the latter case, the logic unit 12 triggers the visualization or the production
of an alarm or warning signal, for example acoustic or displayed in control panel
14.
[0146] After the command (either to change the program's setting or - additionally - to
emit a warning signal), waiting time step 7F is reached.
[0147] If during the waiting time 7F, which may for example lasts 30 seconds, there is no
user input, that is, if the user does not react (step 9F), then the selected washing
program starts in step 11F.
[0148] The washing process begins, main water supply is executed to supply water into the
drum 6 (wash water) until a target water amount for washing set according to the set
washing program. The amount of water is preferably big enough that the laundry is
in contact to the water. A first level of water inside the drum is reached and it
is measured. However, this first water level is lowered as laundry absorbs water in
the drum 6. If after a pre-determined time interval, the laundry has absorbed so much
water that the difference between the new - second - water level at the end of the
predetermined time interval and the first water level is above a given value considered
as a threshold, water supply to additionally supply water is executed accordingly.
The water is not supplied any more if after the pre-determined time interval the difference
between the first level and the second level water is below the selected threshold.
The water amount which is introduced in the laundry at the beginning preferably depends
on the set washing program or program.
[0149] After the introduction of the water loading, the washing and/or rinsing process can
proceed. The parameter displayed may slowly change as the washing process proceed,
for example in case of a display of the duration of the program, the remaining time
till the end of the program is continuously updated in a countdown manner.
[0150] In certain conditions, a more accurate evaluation of the weight of the laundry is
performed by means of the second weight sensor 16 is step 12F. To perform this calculation,
a pre-defined amount of water is preferably introduced into the drum 6. The water
level is lowered as laundry absorbs water. If after a pre-determined time interval,
the laundry has absorbed so much water that the difference between a first water level
at the beginning of the predetermined time interval and a second water level at the
end of the predetermined time interval is above a given value considered as a threshold,
water supply to additionally supply water is executed accordingly. The water is not
supplied any more if after the pre-determined time interval the difference between
the first and second level is below the threshold.
[0151] Since weight of laundry is proportional to an amount of absorbing water from laundry,
the second weight of laundry may be determined according to the number of water resupplies,
in each of which a known amount of water is introduced in the drum. That is, since
the number of water resupplies varies according to weight of laundry, the second weight
of the laundry can be calculated in a more precise manner. Alternatively, not only
the number of water resupplies is used to calculate the load of the laundry, but also
the time the water takes to maintain the desired water level.
[0152] The same parameter which has been determined using the first weight is then recalculated,
for example the duration of the washing program. The display is updated with the new
value of the parameter, which is optimized for washing programs in which there is
a heavy load. For example, the display may show a new time duration of the program,
and the visualized value may perform a noncontinuous "jump" from the previously displayed
value obtained on the basis of the first weight to a new value obtained on the basis
of the second weight.
[0153] At the end of the washing program, the machine stops.
[0154] Alternatively, in case there is a user input in step 9F, untangling movements are
performed (step 10F). Drum 6 is rotated at a second speed, preferably lower than the
first speed, to re-distribute the laundry inside the drum. The amount of laundry has
possibly been modified by the user. After the untangling movements, the method of
the invention re-starts from step 2F, where rotation of the drum at the first speed
is performed (see figure 5) and a calculation of the torque and/or unbalance is made.