DESCRIPTION
[0001] The present invention relates to a household appliance for treating soft goods according
to the preamble of claim 1.
[0002] In particular, the invention relates to household laundry washing machines.
[0003] The term "laundry washing machine" is used herein to designate a machine suited to
carrying out at least one wash treatment on soft goods. A laundry washing machine
may be a so-called "washing machine" (intended for washing only) or a so-called "washing/drying
machine", which can also carry out a drying treatment on soft goods (in particular
by means of hot air blown into the wash tub by a blower assembly).
[0004] Known household appliances for treating soft goods include a swinging assembly into
which the items to be treated are loaded. The swinging assembly is elastically constrained
to a frame by means of a suspension system.
[0005] In laundry washing machines, the swinging assembly comprises a tub in which soft
goods are washed.
[0006] Soft goods can be loaded from the front side, through an opening obtained in the
front wall of the machine, or from the top, through an opening obtained in the top
wall of the machine.
[0007] Several typologies of sensing devices are available for the household appliances
currently available on the market to measure the relative displacement of the swinging
assembly with respect to the appliance frame, in order to detect, for example, the
mass or weight of the laundry being present inside the appliance and/or the value
of any load imbalance during the operation of the appliance and/or the quantity of
wash water supplied into the tub.
[0008] Said sensing devices are often built in one of the mechanical components of the household
appliance.
[0009] If the household appliance is a laundry washing machine, the sensing devices used
for measuring the relative displacement of the swinging assembly with respect to the
appliance frame may suitably be mounted to one of the dampers comprised in the suspension
system of the appliance. In such a case, the relative displacement between the piston
and the cylinder of the damper is used to detect the relative displacement of the
swinging assembly with respect to the frame. It should be reminded that the commonly
used terms "cylinder" and "piston" respectively refer to the outer and inner elements
of a damper, which are adapted to move telescopically.
[0010] Patent
DE4319614 describes a front-loading laundry washing machine with a swinging assembly suspended
on two springs and connected to the frame through two dampers. In one of the two dampers,
a Hall-effect sensing device is installed on the piston and a permanent magnet is
installed on the cylinder. The relative displacement between the cylinder and the
piston thus translates into a corresponding relative displacement between the magnet
and the Hall sensor, so that the output of the latter is a voltage value which is
proportional to said relative displacement.
[0011] This solution suffers from the drawback that an accurate displacement reading requires
the use of very expensive permanent magnets (rare-earth type). Also, such sensors
do not allow to obtain a very accurate detection, since small relative movements between
piston and cylinder translate into imperceptible variations in the amplitude of the
voltage signal. The detection of such movements would require very expensive electronics,
which is seldom available in household appliances for treating soft goods.
[0012] Patents
EP1220961 and
EP1094239 disclose a damper for a laundry washing machine wherein a coil is applied to one
of the two movable elements (cylinder and piston), while a ferromagnetic element is
applied to the other element which can affect the inductance value of the coil depending
on its position in the latter. When applying alternating current having a predetermined
amplitude to the coil, the voltage amplitude across the latter is proportional to
the relative displacement between the cylinder and the piston of the damper. By reading
the voltage amplitude across the coil it is therefore possible to obtain the relative
displacement value.
[0013] Though to a lesser extent than the solution using a Hall sensor, this solution also
has some limitations affecting the displacement detection, which are related to the
capability of the electronics to detect small voltage variations.
[0014] According to both of the above-described solutions, in fact, the measurement of the
relative displacement between the piston and the cylinder of the damper is translated
into a direct voltage obtained by processing, through a suitable electronic circuit,
the signal generated by the associated sensor, the latter being a Hall-effect sensor
or a coil, respectively.
[0015] The worst drawback of such an approach is that the electronic circuit used for processing
the signal generated by the displacement sensor is of the analog type, and thus it
is characterized by the typical limitations of that technology, which derive both
from the tolerances and thermal drifts of its components and from a low immunity to
electric noise. Consequently, this solution turns out to be very costly, in that it
implies that it is necessary to use higher quality components characterized by very
strict tolerances and low thermal drift.
[0016] The solutions known in the art, wherein an analog signal is transmitted, also require
the presence of appropriate electromagnetic shielding systems in order to prevent
the readings from being affected by electromagnetic noise.
[0017] An analog electric circuit which can be used for processing the signal generated
by a displacement sensor based on a coil and a ferromagnetic element, respectively
located on two movable elements of a damper for a laundry washing machine, is described,
for example, in patent
EP654140.
[0018] Document
JP 6-246087 discloses a washing machine wherein an outer tub is suspended from a machine frame
through a plurality of suspension rods provided with weight sensors consisting of
cores and coils.
[0019] It is the object of the present invention to overcome the above-mentioned limitations
of the prior art.
[0020] In particular, it is an object of the present invention to provide a solution, preferably
a low-cost one, for accurately measuring the relative displacement between two telescopically
coupled elements (in particular the cylinder and the piston of a damper) of a suspension
system of a household appliance for treating soft goods.
[0021] These and other objects of the present invention are achieved through a household
appliance incorporating the features set out in the appended claims, which are intended
as an integral part of the present description.
[0022] The invention is based on the general idea of providing an electronic module comprising
an oscillator circuit, the oscillation frequency of which depends on the impedance
of a coil located on one of the two telescopically coupled elements.
[0023] The relative displacement between the two elements (coinciding with the relative
displacement between the swinging assembly and the appliance frame) is thus determined
by an electronic detection module as a function of the oscillation frequency of said
oscillator circuit, which is measured, for example, by a microcontroller included
in said electronic module. The relative displacement S is therefore measured by exploiting
the fact that the value of the inductance L of the coil depends on the axial penetration
x of one of the two elements within the volume of the coil itself. As a result, the
frequency value f of the signal, preferably a square-wave signal, generated by the
oscillator circuit (which incorporates the coil) depends on said inductance value
L, and is therefore related to said relative displacement S.
[0024] In addition to measuring the relative displacement S of the two movable elements,
the present invention also provides for assessing one or more quantities associated
with said relative displacement S (such as, for example, the weight of the soft goods
contained in the drum of the washing machine and/or the quantity of water supplied
into the tub and/or the imbalance of the laundry load) by measuring a value of frequency
instead of a value of voltage amplitude as in the prior art.
[0025] A microcontroller included in the electronic module according to the present invention
processes locally the signal output by the oscillator circuit in order to obtain,
based on its frequency f, the value of the relative displacement S between the two
elements and/or of any other physical quantities associated with said relative displacement
S (such as the weight of the laundry placed in the drum of the washing or washing/drying
machine). Advantageously, the microcontroller sends the result of said processing
to the electronic control system of the household appliance over a suitable digital
communication line. According to an advantageous embodiment of the present invention,
which is aimed at ensuring higher measurement accuracy and reliability over time,
said local processing may take into account one or more external interference factors
adversely affecting the quality of the relative displacement reading S.
[0026] The household appliance according to the present invention will become apparent,
together with its further advantages, from the following detailed description and
from the annexed drawings, which are supplied by way of non-limiting example, wherein:
Fig. 1 is a sectional view of a damper of a household appliance according to a first
embodiment of the present invention;
Fig. 2a is a block diagram of an electronic detection module known in the art, used
for detecting the relative displacement between the cylinder and the piston of a damper
for a laundry washing machine by measuring the voltage amplitude variation across
a coil located on the damper cylinder;
Fig. 2b is a block diagram of an electronic detection module according to the invention,
which is adapted to detect the relative displacement between the cylinder and the
piston of a damper for a laundry washing machine through frequency measurements;
Fig. 3 is a global view of a damper, an electronic detection module and an electronic
control system of a household appliance according to the present invention;
Fig. 4 is a sectional view of a damper of a household appliance according to a second
embodiment of the present invention.
[0027] In the following description, reference will be made to a laundry washing machine
as a preferred but non-limiting example of application of the present invention.
[0028] Fig. 1 shows a damper 1 included in the suspension system of a laundry washing machine
according to the present invention.
[0029] Said laundry washing machine, which may be a washing or washing/drying machine, comprises
a frame and a swinging assembly, the latter comprising in turn a drum adapted to house
soft goods to be treated and to be rotated about its axis by means of a motor device,
and a tub adapted to contain water and/or wash liquid used for performing the treatment.
A suspension system connects the swinging assembly to the frame while keeping it elastically
suspended. Said household appliance also comprises an electronic control system with
a central controller, and possibly an interface device adapted to provide information
to the user of the household appliance. Said interface device may be a luminous device,
e.g. an electronic display or a LED array, or else an acoustic device, e.g. a buzzer
or a voice synthesizer.
[0030] In order to improve the operation of the laundry washing machine, it is useful to
measure the relative displacement between the swinging assembly and the frame. In
fact, said measurement allows, in static conditions, to know certain characteristics
of the load being present in the household appliance, whereas in dynamic conditions
it allows to quantify the imbalance of the load inside the drum and/or the vibration
of the swinging assembly, or to determine the maximum admissible spin speed. Particularly
interesting is the possibility of using the relative displacement of the swinging
assembly with respect to the frame in static conditions to obtain the mass or weight
of the laundry contained in the drum, preferably the mass or weight of the laundry
loaded in the drum by the user before starting a wash treatment.
[0031] A laundry washing machine, which is the subject of the present invention, comprises,
in its suspension system, dampers connected to the swinging assembly (i.e. to the
tub assembly) through an upper fixing and to the frame through a bottom fixing hinged
to a pin. The dampers provide the very important function of damping the oscillations
of the swinging assembly, mostly during the spin phases. Said dampers comprise a cylinder,
i.e. a cylindrical tubular element, within which a piston, which typically is also
a cylindrical tubular element, slides and is braked by a braking element capable of
generating adequate friction between the outer surface of the piston and the inner
surface of the cylinder.
[0032] The damper 1 shown in Fig. 1, which is adapted to be installed in a household appliance
according to the present invention, comprises two elements (piston 4 and cylinder
3) telescopically coupled together through two ends. Said elements are adapted to
move reciprocally, in particular the first element being adapted to slide relative
to the second element in an essentially straight direction. Both the piston 4 and
the cylinder 3 have preferably an axially symmetrical shape, in particular a cylindrical
shape, and are both preferably hollow.
[0033] A braking element 5, preferably made of a material having a high friction coefficient,
is constrained to one of the two elements of the damper 1 (e.g. the cylinder 3), so
as to come into contact with the other element (e.g. the piston 4), thus countering
the relative sliding motion between the two elements.
[0034] Seats 10A and 10B are obtained at the ends of the damper 1 for the top and bottom
fixings of the damper 1.
[0035] A coil 9, consisting of a wire made of an electrically conductive material, is wound
coaxially around the cylinder 3 for a length P, so that one end of the piston 4, at
least partly made of ferromagnetic material and sliding axially within the cylinder
3 under the effect, for example, of the weight of the laundry loaded in the drum of
the washing machine, alters the flow of the magnetic field generated by the coil 9
when alternating current flows therethrough, thus changing the inductance value L
of the coil 9 as a function of the penetration x of the piston 4 in the cylinder 3,
the correlation between inductance L and penetration x being expressed by a linear
or non-linear mathematical expression.
[0036] An electronic detection module 6, electrically connected to the coil 9 by means of
the wiring 8, is constrained to the cylinder 3 through a header 13 fixed on the cylinder
3 with screws 7A and 7B. The electronic detection module 6 is electrically connected
to the central controller of the household appliance by means of the wiring 14 (which
may also act as a digital communication line). In the preferred embodiment, the electronic
detection module is powered through the central controller. The wiring 14 may have
its wires welded to the electronic module 6 or else, according to a technically equivalent
solution, it may use a suitable connector on the electronic module 6, which allows
to connect the electric wires that connect the electronic module 6 to the central
controller. Fig. 2a shows a schematic diagram of an analog electric circuit, known
in the art because described in detail, for example, in patent
EP654140, through which it is possible to obtain the value of the relative displacement between
the two movable elements (cylinder and piston) of a damper of a laundry washing machine,
by appropriately processing the voltage signal detected across the impedance coil
Z3, the inductance L of which depends on the relative displacement between cylinder
and piston. For this purpose, the coil is supplied, by means of a generator G, with
a sinusoidal alternating voltage Vac having fixed frequency f
0 through two impedances Z1 and Z2 in series, which for simplicity are supposed herein
to be purely of the resistive type, so that current Iac=Vac/(Z1+Z2+Z3) flows through
the coil. As the inductance value L of the coil changes, the impedance Z3 thereof
changes as well in accordance with the known relationship Z3=R+jω
0L (where ω
0=2πf
0), and so does the voltage drop V3 across its terminals. The sinusoidal signal V3,
having fixed frequency f
0, is read by a special analog detection module AM which, through suitable analog AC-DC
conversion, filtering and scaling steps performed on the output signal, transforms
the latter into a direct signal Vdc, the value of which is dependent on the coil inductance
value L and therefore also on the relative position of the two movable elements of
the damper, on which said inductance L depends. In summary, the known method usually
adopted for measuring variations in the coil inductance L is characterized by the
following three steps:
application of a sinusoidal voltage Vac, having known amplitude and frequency f0, to an electric circuit consisting of a series of impedances, among which the impedance
Z3 of the coil with inductance L, which changes depending on the relative displacement
of the two movable elements of the damper;
measurement of the voltage drop V3 across the coil terminals;
analog processing of the sinusoidal signal V3 and generation of the direct-voltage
output signal Vdc, which is representative of the relative displacement of said two
movable elements of the damper.
Fig. 2b shows a schematic diagram of an electric circuit according to the present
invention, through which it is possible to obtain the value of the relative displacement
S between the cylinder 3 and the piston 4 of the damper 1 for a laundry washing machine.
[0037] The circuit diagram of Fig. 2b is based on a new method for detecting the displacement
S provided as an alternative to the one known in the art and characterized by the
following steps:
use of an oscillator circuit, preferably of the square-wave type (e.g. a "non stable
multivibrator"), the oscillation frequency f of which depends on the coil inductance
value L;
determination of the oscillation frequency of said oscillator circuit;
determination of the relative displacement S of the two movable elements as a function
of said oscillation frequency.
[0038] By using a non stable multivibrator or an equivalent oscillator circuit, the determination
of the displacement takes place in a fully digital manner through the following steps:
digital measurement of the frequency f of the square-wave signal generated by said
oscillator circuit, carried out by means of a suitable input CNT of a microcontroller
MC;
digital processing of the frequency value f read by the microcontroller MC, and
generation of a digital datum being representative of the relative displacement S
of the two movable elements of the damper.
[0039] Of course, the measurement of the oscillation frequency also allows to determine
any other physical quantity related to the relative displacement S.
[0040] In the method known in the art (Fig. 2a), a sinusoidal signal having constant frequency
f
0 is forced through the voltage generator G and the voltage drop V3 is measured across
the coil terminals; the method according to the invention (Fig. 2b), on the contrary,
does not employ a voltage generator with fixed-frequency, but a non stable oscillator
OSC with square-wave signal and variable frequency f, the frequency f being dependent
on the coil inductance value L, and the frequency f is measured digitally.
[0041] It follows that these two methods, although referring to the same damper architecture
intended for use in a washing or washing/drying machine, such as the one shown in
Fig. 1, detect the value of the relative displacement between the two movable elements
of the damper by measuring two completely different quantities: a sinusoidal voltage
V3 in the former case and a frequency f in the latter case.
[0042] Moreover, if we take into consideration the preferred embodiment of the present invention,
which uses a non stable multivibrator, the measured quantity is processed in a purely
analog manner in the former case, whereas it its processed in a fully digital manner
in the latter case. The use of digital processing techniques allows to cut down the
cost of the solution according to the invention: all measurement, calibration and
data processing operations can be carried out by using a low-cost microcontroller
MC (e.g. an 8-pin commercial microcontroller, typically costing around $0.4-0.5).
[0043] A further advantage of the solution according to the present invention is that the
electronic detection module 6 can provide the central controller of the household
appliance, directly and in digital format (e.g. over a serial channel), with the value
of the quantity (e.g. the weight of the laundry loaded in the drum of the washing
machine) associated with the relative displacement S of the two movable elements of
the damper. Instead, the datum output by the analog detection module AM in known solutions
(Fig. 2a) cannot be used directly by the microcontroller: the output variable, consisting
of the direct voltage Vdc, must be subsequently converted into digital format and
processed by the control system of the appliance for the purpose of obtaining the
value of the desired quantity (e.g. the weight of the laundry loaded in the drum of
the appliance).
[0044] A more detailed analysis of the invention will now be provided with reference to
Fig. 3, which diagrammatically shows the following:
a possible embodiment of the electronic detection module 6 according to the present
invention,
the coil 9, located in the damper 1 of the household appliance and used for measuring
the relative displacement S between the cylinder 3 and the piston 4 of the damper
1, and the serial connection, schematically represented by the wiring 14, to the electronic
control system, in particular to the central controller 17 of the household appliance.
[0045] The piston 4 is drawn with a continuous line in a first position and with a dotted
line in a second position, said first position being the position of the piston 4
before a relative displacement S occurs with respect to the cylinder 3 (and therefore
with respect to the coil 9, which is integral with the cylinder 3), and said second
position being the position of the piston 4 after a relative displacement S has occurred.
[0046] The value of the relative displacement S between the piston 4 and the cylinder 3
is given by the difference between the initial value x
0 of the axial penetration of the piston 4 in the inner volume of the coil 9 and the
final value x
1 of the axial penetration of the piston 4 in the inner volume of the coil 9. x
s and x
i designate the upper and lower filling limits, respectively, of the inner volume of
the coil 9, where x
s-x
i=P.
[0047] As shown in Fig. 3, the coil 9 is electrically connected (by means of the wiring
8) to an oscillator circuit 12 and determines, based on its inductance value L, the
oscillation frequency f of the alternating signal generated by said oscillator circuit
12. The value of said frequency f can therefore be expressed by means of a mathematical
function such as f=F(L), wherein the inductance L is an independent variable. In the
example of Fig. 3, the alternating signal generated by the oscillator circuit 12 consists
of a square wave having a voltage swinging between a low voltage level (associated
with logic level 0) and a high voltage level (associated with logic level 1). The
signal generated by the oscillator circuit is sent to a digital input of the microcontroller
16 which, through a suitable digital counter CNT, measures the number of oscillations
per second of the signal, i.e. it determines the oscillation frequency f of the oscillator
circuit 12. Based on the reading of the frequency value f, the microcontroller 16
calculates the relative displacement S of the piston 4 with respect to the cylinder
3 of the damper 1, and thus also, for example, the weight of the contents of the drum
of the washing machine. The relationship between the oscillator frequency value and
the weight of the laundry being present in the drum of the washing machine is determined
experimentally and can be expressed through a mathematical algorithm or data tables
managed by the control program of the microcontroller 16.
[0048] The household appliance for treating soft goods, in particular the laundry washing
machine, according to the present invention, is of the electronically controlled type
and includes a central controller 17 adapted to control the household appliance by
adjusting and controlling the various laundry treatment phases based on instructions
received from the user and on data detected by sensor means, among which the data
supplied by the electronic detection module 6.
[0049] As previously mentioned, the household appliance comprises a frame and a swinging
assembly. The swinging assembly is connected to the frame by means of a suspension
system, which comprises a pair of elements telescopically coupled to each other through
two respective ends, wherein a first of said two ends comprises ferromagnetic material
and a second of said two ends comprises a coil 9.
[0050] According to the invention, the household appliance comprises an electronic detection
module 6 adapted to detect a relative displacement S of said two ends. Said electronic
detection module 6 comprises an oscillator circuit 12 having an oscillation frequency
f which depends on the impedance L of the coil 9, and processing means, operationally
connected to said oscillator 12 and adapted to detect said oscillation frequency f
and to determine, as a function of said oscillation frequency f, at least one piece
of information which can be associated with the relative displacement S. Said piece
of information may also be associated, in particular in static conditions, wherein
no relative displacement S has occurred between the cylinder 3 and the piston 4, with
the absolute position of the swinging assembly with respect to the frame, which can
be deduced from the absolute value of the axial penetration x of the end of the piston
4, made of ferromagnetic material, in the inner volume of the coil 9.
[0051] According to the embodiment of Fig. 1, the coil 9 is located on the cylinder 3 of
the damper, whereas the piston 4 includes at least a portion made of ferromagnetic
material which travels in the cylinder 3, thereby changing the inductance of the coil
9.
[0052] Said embodiment can be modified, without departing from the scope of the present
invention, according to a fully technically equivalent alternative configuration,
by associating the coil 9 with the piston 4 and by manufacturing the cylinder 3 from
ferromagnetic material, as shown in Fig. 4.
[0053] Fig. 4 uses the same reference number as Fig. 1 to designate means which are identical
or equivalent to those already shown in Fig. 1.
[0054] According to this embodiment, the piston 4 has one end 41 telescopically coupled
to one end of the cylinder 3. The end 41 is hollow and is wound with a coil 9 connected
to the electronic detection module 6 by means of a wiring 8.
[0055] In its turn, the cylinder 3 has one end 31 at least partly made of ferromagnetic
material, which is inserted telescopically in the cavity of the end 41 of the piston
4.
[0056] The relative displacement of the end 31 with respect to the end 41 causes a variation
in the inductance of the coil 9. This variation, as described previously, determines
a variation in the oscillation frequency f of an oscillator 12 comprised in the electronic
detection module 6.
[0057] Said electronic detection module 6 comprises a microcontroller 16 which, being fitted
with a suitable counter CNT, measures the oscillation frequency f of the oscillator
circuit 12 and determines the relative displacement between the cylinder 3 and the
piston 4. The counter CNT is operationally connected to the oscillator circuit 12
and is adapted to count the phase transitions of the output signal generated by the
oscillator circuit 12. According to the present invention, the microcontroller 16
is adapted to transmit to the central controller 17, over a digital communication
line, a piece of information which can be associated with the relative displacement
S of the swinging assembly with respect to the frame.
[0058] The digital communication line between the microcontroller 16 and the central controller
17 includes appropriate transmission means, typically of the electric type, and the
transmission of suitable digital signals is managed through appropriate communication
protocols.
[0059] Based on said piece of information which can be associated with the relative displacement
S, the central controller 17 can therefore exert at least one control action on the
household appliance.
[0060] In particular, said information may be a measurement of the mass or weight of the
contents of the swinging assembly or of a portion of the contents of the swinging
assembly.
[0061] More in particular, said piece of information is the value of the mass or weight
of the soft goods loaded in the swinging assembly before a wash treatment is started:
the central controller 17 can use this measurement of the mass or weight of the soft
goods loaded in the swinging assembly for calculating at least one parameter related
to a subsequent wash treatment, said parameter being preferably the appropriate quantity
of water or the appropriate quantity of washing agents. As an alternative, said piece
of information which can be associated with the relative displacement S of the swinging
assembly with respect to the frame may be the measurement of the mass or weight of
the water or wash liquid in the swinging assembly during the operation of the household
appliance.
[0062] According to a preferred embodiment, the microcontroller 16 is a slave unit of the
central controller 17, whereto it is connected by means of the wiring 14, and the
microcontroller 16 can receive instructions from the central controller 17.
[0063] It is apparent that the microcontroller 16 may be positioned without distinction
either on the same PCB board housing the oscillator circuit or at a distance from
said circuit.
[0064] In the preferred embodiment, the entire electronic module 6 is located near the coil
9 in order to minimize the length of the connections between microcontroller 16, oscillator
circuit 12 and coil 9, thus ensuring the utmost immunity to electromagnetic noise.
Advantageously, a calibration step may be performed, e.g. during the final testing
of the household appliance, for making the microcontroller 16 capable of associating
any possible reading of the frequency f of the square-wave signal generated by the
oscillator 12 with a digital signal which is interpreted by the central controller
17 as being representative of a particular value of the relative displacement of the
swinging assembly with respect to the frame and/or of a particular value of one or
more physical quantities related to said relative displacement (such as the mass or
weight of the soft goods contained in the drum).
[0065] The microcontroller 16 transmits a digital signal to the central controller 17 over
the communication line consisting of the wiring 14.
[0066] It should be underlined that the digital transmission from the microcontroller 16
to the central controller 17 is much more robust than a simple analog connection between
the analog module AM (shown in Fig. 2a) and the central controller 17, since it is
essentially immune from noise and does not require any special shielding for the wiring
14 connecting the electronic module 6 to the central controller 17. This ensures high
reliability and accuracy of the measurements carried out by using the value of the
frequency f of the square-wave signal generated by the oscillator 12, corresponding
to the measurement of the relative displacement of the swinging assembly with respect
to the frame and to the measurements of the mass or weight of the contents of the
swinging assembly.
[0067] The microcontroller 16, which is adapted to generate, through the measurement of
the frequency f of the alternating voltage signal generated by the oscillator circuit
12, a digital signal being representative of the relative displacement S of the swinging
assembly with respect to the frame and/or of any other physical quantities related
to said relative displacement S (among which, for example, the mass or weight of the
soft goods contained in the drum), is also adapted to process the measured value of
the frequency f of the square-wave voltage signal generated by the oscillator circuit
12 in order to compensate for any errors caused by external interference. For instance,
the microcontroller 16 subjects the measured value of the frequency f to a digital
processing step in order to compensate for any errors due to external environmental
factors (e.g. temperature) or to wear of mechanical components of the suspension system
of the household appliance.
[0068] Said compensation may take place on the basis of signals sent by sensor means adapted
to detect operating parameters of the appliance (e.g. according to the output signal
of a temperature sensor 18 located on the header 13 for detecting the temperature
near the damper 1, said header being suitably secured thereto), or else on the basis
of algorithms taking into account the variation over time of the elasticity and/or
damping characteristics of the suspension system of the household appliance. More
in detail, said algorithms consist of software code portions created on the basis
of data acquired experimentally and adapted to counter the loss of accuracy and reliability
over time of both the measurement of the relative displacement of the swinging assembly
with respect to the appliance frame and the measurement of any other physical quantity
which can be obtained from said relative displacement.
[0069] According to a particularly advantageous embodiment of the present invention, the
laundry washing machine comprises sensor means operationally connected to the microcontroller
16 and adapted to detect operating parameters of the household appliance, wherein
at least one of said sensor means may be incorporated into the electronic module 6.
The electronic module 6 shown in Fig. 3 also comprises a temperature sensor 18, which
is preferably an NTC type sensor, used for determining the value of the temperature
in the area of the header 13. The temperature sensor 18 may be suitably interfaced
with an analog channel of the microcontroller 16 or incorporated into the microcontroller
16 (since low-cost microcontrollers having a built-in temperature sensor are currently
available on the market). During the operation of the household appliance, said area
is in fact subject to the action of the nearby braking element 5, which dissipates
a portion of the kinetic energy of the swinging assembly as heat: in particular, said
action of the braking element 5 of the damper 1 is perceived as a temperature value
being higher than room temperature, which may cause drifts altering the measurement
of the relative displacement of the swinging assembly with respect to the appliance
frame.
[0070] Moreover, this temperature variation can affect the friction in the damper, thus
changing the laws that regulate the relationship between displacement and other associated
quantities, such as the weight of the soft goods loaded in a washing machine.
[0071] The temperature sensor 18 generates an auxiliary electric signal being representative
of the temperature in the area of the header 13, and then sends it to the microcontroller
16. The microcontroller 16 takes into account the auxiliary electric signal received
from the temperature sensor 18 for generating the information to be sent to the central
controller 17 over a digital communication line.
[0072] The microcontroller 16 compensates the measured value of the relative displacement
of the swinging assembly with respect to the appliance frame (or of any other physical
quantity related to said displacement) based on the temperature value detected by
the temperature sensor 18, considering how the electric characteristics of the coil
9 and of the oscillator circuit 12 change as a function of temperature.
[0073] In the example of Fig. 3, the temperature sensor 18 is included in the architecture
of the electronic module 6.
[0074] Advantageously, different sensor means may be conveniently associated with the electronic
module 6 in order to detect different physical quantities: for example, a (relative
or absolute) humidity sensor adapted to detect the humidity in the air surrounding
the electronic module 6 and to prevent said electronic module 6 from suffering any
damage due to excessive humidity, or a microphone adapted to detect the noise produced
by the laundry washing machine in order to provide a warning in the event that there
is a risk of impending failure of the damper 1 or of any other components of the laundry
washing machine according to the present invention. Preferably, the microcontroller
16 may also be adapted to counter the effects caused by wear of the household appliance,
which translates into variations over time in the elasticity and damping characteristics
of the suspension system of the laundry washing machine and therefore in the frequency
of the signal generated by the oscillator 12.
[0075] Said variations in the elasticity and/or damping characteristics are detected as
the number of operation cycles of the appliance increases, and are due to wear occurring
over time. For example, if the electronic module 6 according to the present invention
is to be used for detecting the mass or weight of the contents of the swinging assembly
of the laundry washing machine, it should be taken into consideration that, as time
goes by, a different relative displacement of the swinging assembly may occur, the
mass or weight of the contents of the swinging assembly being equal.
[0076] In this case, the microcontroller 16 may be made capable of compensating for the
effect exerted by variations over time in the elasticity and/or damping characteristics
of the suspension system of the laundry washing machine on the detection of the mass
or weight of the contents of the swinging assembly. To this end, the microcontroller
16 may, by way of non-limiting example, count the number of operation cycles carried
out by the machine and then, based on said number, associate the value of the frequency
f of the signal generated by the oscillator 12 with one of several experimentally
obtained corrective factors, stored in the internal memory of the microcontroller
16. Thus, the microcontroller 16 performs a compensation action which allows to obtain
a sufficiently accurate and reliable measurement of the mass or weight of the contents
of the swinging assembly over time.
[0077] More preferably, the information relating to the treatment cycles carried out by
the household appliance, just like any other information pertaining to the wear suffered
by the household appliance, can be transmitted to the microcontroller 16 by the central
controller 17.
[0078] In comparison with the measurement system according to the prior art, the present
invention offers the additional advantage of significantly reducing the workload of
the electronic control system of the household appliance, in particular of the central
controller 17.
[0079] In fact, the information sent by the microcontroller 16 of the electronic module
6 can be used by the central controller 17 directly, without requiring any further
processing, since said processing has already been carried out upstream of the central
controller 17. The latter simply has to decode the digital signal sent by the microcontroller
16 to have the information contained therein available for controlling the household
appliance.
[0080] The transmission of the above information from the microcontroller 16 to the central
controller 17 may be provided by using well-known communication techniques.
[0081] The communication between the microcontroller 16 and the central controller 17 by
means of the wiring 14 may be a unidirectional communication (e.g. according to the
PWM technique, wherein the information is coded by acting on the duty cycle of the
digital signal, which therefore consists of a series of pulses having constant amplitude
and frequency and variable width), or preferably a bidirectional communication (by
way of non-limiting example, one may use a UART-type asynchronous serial bidirectional
communication).
[0082] Over the transmission line T, the microcontroller 16 transmits to the central controller
17, in the form of a digital signal, a piece of information which can be associated
with the relative displacement of the swinging assembly with respect to the appliance
frame (i.e. the relative displacement reading o any other physical quantity related
to said relative displacement) and which is suitably compensated for temperature and
wear of the mechanical components of the appliance.
[0083] Over the reception line R, the microcontroller 16 receives from the central controller
17 data which is useful for the microcontroller 16. For example, the central controller
17 may transmit to the microcontroller 16 the value of the rotational speed of the
drum of the laundry washing machine, so that the microcontroller 16 can take it into
account when assessing the variation over time in the elasticity and/or damping characteristics
of the suspension system. Or, still by way of example, the central controller 17 may
send to the microcontroller 16 information relating to the dynamic state of the system,
so that the microcontroller 16 can more easily discern whether the ongoing measurement
is a static measurement (such as a measurement of the mass or weight of the laundry
contained in the drum before the wash treatment is started) or a dynamic measurement
(such as a measurement of load imbalance during the operation of the household appliance).
[0084] The information indicating the value of the mass or weight of the laundry may be
used by the machine for treating soft goods for the purpose of both providing useful
information to the user through its own interface device (e.g. the laundry washing
machine may warn the user when the maximum laundry load which can be treated by the
household appliance has been reached, depending on the type of fabric, or it may suggest
the appropriate quantity of washing agents to be used for a certain quantity of laundry
loaded in the drum, or it may give advice as to the most appropriate wash program)
and of automatically adapting the characteristic parameters of the treatment, in particular
of the wash treatment, to the quantity of laundry loaded in the drum by the user,
so as to optimize the consumption of the household appliance (if the laundry washing
machine is fitted with a high-capacity washing agent dispensing device, knowing the
value of the mass or weight of the laundry loaded in the drum will allow for an optimal
metering of the washing agents).
[0085] In order to allow the electronic detection module 6 according to the present invention
to carry out accurate and reliable measurements of the mass or weight of the contents
of the swinging assembly or of a portion thereof, the central controller 17 transmits
to the microcontroller 16 (assuming the existence of a bidirectional communication
line between the two) at least one datum which can be used by the microcontroller
16 as a synchronism signal.
[0086] If the measurement concerns the mass or weight of the laundry loaded in the drum
of the laundry washing machine, it is useful to adopt a synchronism signal indicating
an empty condition inside the swinging assembly of the household appliance, which
allows the microcontroller 16 to associate the offset detected when receiving the
synchronism signal with the tare value.
[0087] Said synchronism signal transforms the measurements of the mass or weight of the
contents of the swinging assembly of the laundry washing machine into differential
measurements, the value of the mass or weight of the laundry loaded in the drum being
therefore calculated by the microcontroller 16 as a difference between the mass or
weight value corresponding to the frequency value instantaneously associated with
the square-wave signal generated by the oscillator circuit 12 and the mass or weight
value corresponding to the frequency value associated with the square-wave signal
generated when the synchronism signal is sent.
[0088] In the most advantageous embodiment of the present invention, wherein the communication
between the central controller 17 and the microcontroller 16 is bidirectional, the
synchronism signal may be provided by the signal indicating that the door of the laundry
washing machine has been opened, which is sent to the microcontroller 16 by the central
controller 17 after having received it from the door locking device.
[0089] As an alternative, a dedicated calibration push-button may be provided inside the
interface device, i.e. a push-button available to the user to notify the empty condition
inside the swinging assembly to the central controller 17: in this case, the synchronism
signal may be provided by a signal indicating that said push-button has been pressed.
By performing differential measurements, the electronic detection module 6 according
to the present invention can also operate as a water or wash liquid quantity sensor.
In fact, by using the start signal of the laundry washing machine as a synchronism
signal once the laundry has been loaded in the drum, it is possible to measure the
mass or weight of the water or wash liquid inside the swinging assembly. In fact,
the mass and weight of the water or wash liquid can be calculated by the microcontroller
16 as a difference between the mass or weight value obtained instantaneously during
the operation of the laundry washing machine and the mass or weight value obtained
when the synchronism signal is sent, i.e. when the laundry washing machine is started.
[0090] By working as a water or wash liquid quantity sensor, the electronic detection module
6 allows the central controller 17 to control the water intake and/or drain means
of the laundry washing machine (determining the opening and closing times thereof)
solely as a function of the information relating to the mass or weight of the water
or wash liquid being present inside the swinging assembly.
[0091] If the household appliance according to the present invention is a washing/drying
machine, the electronic detection module 6 may also be used for controlling the drying
treatment.
[0092] During the drying treatment, the microcontroller 16 can transmit to the central controller
17, instant by instant, the information relating to the mass or weight of the swinging
assembly, and the central controller 17 can use said information to control the drying
treatment. Likewise, the microcontroller 16 can determine the quantity of water progressively
removed from the laundry by calculating it based on the reduction in the mass or weight
of the contents of the swinging assembly, and the central controller 17 can stop the
drying treatment when the quantity of water removed from the laundry reaches a predetermined
percentage of the quantity of water contained inside the swinging assembly at the
end of the wash treatment.
[0093] It is apparent from the present description that the household appliance according
to the present invention, besides overcoming the above-mentioned inherent drawbacks
of the prior art, also offers the additional advantage of allowing to use the electronic
module 6 for controlling many operational phases of the household appliance without
increasing the workload of the central controller 17.
[0094] The present invention has been described with particular reference to some specific
embodiment examples, but it is clear that many changes may be made thereto by those
skilled in the art without departing from the scope defined by the appended claims.
[0095] For example, the detection of the relative displacement of the swinging assembly
with respect to the frame may be provided by using a pair of telescopically coupled
elements not necessarily consisting of the piston and cylinder of a damper. These
two elements may be a pair of elements specifically conceived for said detection,
but nonetheless having no function as a damper.
1. Household appliance for treating soft goods, in particular a laundry washing machine,
comprising:
- a swinging assembly elastically constrained to a frame by means of a suspension
system comprising a pair of elements (3, 4) telescopically coupled to each other through
two respective ends, wherein a first of said two ends comprises ferromagnetic material
and a second of said two ends comprises a coil (9), and
- an electronic detection module (6) adapted to detect a relative displacement of
said two ends,
characterized in that said electronic module (6) is located on one of said two elements (3, 4) and comprises
an oscillator circuit (12), the oscillation frequency of which depends on the impedance
of said coil (9), and processing means operationally connected to said oscillator
and adapted to measure said oscillation frequency and to determine, as a function
of said oscillation frequency, at least one piece of information which can be associated
with said relative displacement, said information being the measurement of the mass
or weight of the soft goods loaded in said swinging assembly before said soft goods
are subjected to a treatment, in particular a wash treatment.
2. Household appliance according to any of the preceding claims, characterized in that said oscillator circuit (12) is adapted to generate a square-wave signal.
3. Household appliance according to any of the preceding claims, characterized in that said oscillator is a non stable multivibrator.
4. Household appliance according to any of the preceding claims, characterized by comprising sensor means operationally connected to said microcontroller (16) and
adapted to detect operating parameters of said household appliance.
5. Household appliance according to claim 4, characterized in that said sensor means comprise a temperature sensor (18), preferably an NTC-type sensor.
6. Household appliance according to any of the preceding claims, characterized by comprising an interface device through which said household appliance communicates
said information to a user.
7. Household appliance according to any of the preceding claims, characterized in that said coil (9) is located on one end of the cylinder (3) of a damper (1).
8. Household appliance according to claim 7, characterized in that said end comprising ferromagnetic material is one end of a piston (4) of said damper
(1).
9. Household appliance according to any of claims 1 to 6, characterized in that said coil (9) is located on one end (41) of the piston (4) of a damper (1).
10. Household appliance according to claim 9, characterized in that said end (31) comprising ferromagnetic material is one end of a cylinder of said
damper (1).
11. Method for measuring the mass or weight of soft goods loaded in a swinging assembly
of a washing machine before said soft goods are subjected to a treatment by the washing
machine, comprising the following steps:
- detecting a relative displacement between two elements of the swinging system, wherein
said two elements (3, 4) are telescopically coupled together through two ends, a first
of said two ends comprising ferromagnetic material and a second of said two ends comprising
a coil (9), characterized in that: an electronic detection module (6) adapted to detect the relative displacement of
the ends of said elements (3, 4) is located on one of said two elements and comprises
an oscillation circuit (12),
- an oscillation frequency of an oscillator circuit (12) is detected, which oscillation
frequency depends on the impedance of said coil (9) located on one of said two elements,
- said relative displacement is determined as a function of said oscillation frequency.
12. Method according to claim 11, characterized in that said relative displacement is determined on the basis of information, measured by
sensor means, relating to operating parameters of said household appliance.
13. Method according to claim 11 or 12, characterized in that said relative displacement is determined on the basis of information, transmitted
by a central controller of said household appliance, pertaining to the wear of said
household appliance.
14. Method according to any of claims 11 to 13, characterized by comprising a calibration step, carried out when said swinging assembly is idle, for
the purpose of detecting an idle oscillation frequency of said oscillator circuit
(12).
1. Haushaltsgerät zum Behandeln von weichen Gegenständen, insbesondere Wäschewaschmaschine,
umfassend:
- eine Schwinganordnung, die an einem Rahmen mittels eines Aufhängungssystems elastisch
eingespannt ist, das ein Paar von Elementen (3, 4) aufweist, die durch zwei jeweilige
Enden teleskopisch miteinander gekoppelt sind, wobei ein erstes der zwei Enden ferromagnetisches
Material aufweist und ein zweites der zwei Enden eine Wicklung (9) aufweist, und
- ein elektronisches Erfassungsmodul (6), das dazu ausgelegt ist, eine relative Verlagerung
der zwei Enden zu erfassen,
dadurch gekennzeichnet, dass das elektronische Modul (6) an einem der zwei Elemente (3, 4) angeordnet ist und
eine Oszillatorschaltung (12) aufweist, deren Oszillationsfrequenz von der Impedanz
der Wicklung (9) abhängig ist, und Prozessormittel, die mit dem Oszillator betriebsmäßig
verbunden und dazu ausgelegt sind, die Oszillationsfrequenz zu messen und, als Funktion
der Oszillationsfrequenz, zumindest ein Informationsstück zu bestimmen, das der relativen
Verlagerung zugeordnet werden kann, wobei die Information die Messung der Masse oder
des Gewichts der weichen Gegenstände ist, die in die Schwinganordnung geladen sind,
bevor die weichen Gegenstände einer Behandlung unterzogen werden, insbesondere einer
Waschbehandlung.
2. Haushaltsgerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Oszillatorschaltung (12) dazu ausgelegt ist, ein Rechteckwellensignal zu erzeugen.
3. Haushaltsgerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Oszillator ein nicht-stabiler Multivibrator ist.
4. Haushaltsgerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass es Sensormittel aufweist, die mit dem Microcontroller (16) verbunden und dazu ausgelegt
sind, Betriebsparameter des Haushaltsgeräts zu erfassen.
5. Haushaltsgerät nach Anspruch 4, dadurch gekennzeichnet, dass die Sensormittel einen Temperatursensor (18) aufweisen, bevorzugt einen NTC-Sensor.
6. Haushaltsgerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass es eine Schnittstellenvorrichtung aufweist, durch die das Haushaltsgerät die Information
einem Benutzer kommuniziert.
7. Haushaltsgerät nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Wicklung (9) am einen Ende des Zylinders (9) eines Dämpfers (1) angeordnet ist.
8. Haushaltsgerät nach Anspruch 7, dadurch gekennzeichnet, dass das ferromagnetisches Material aufweisende Ende ein Ende eines Kolbens (4) des Dämpfers
(1) ist.
9. Haushaltsgerät nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Wicklung (9) am einen Ende (41) des Kolbens (4) eines Dämpfers (1) angeordnet
ist.
10. Haushaltsgerät nach Anspruch 9, dadurch gekennzeichnet, dass das ferromagnetisches Material aufweisende Ende (31) ein Ende eines Zylinders des
Dämpfers (1) ist.
11. Verfahren zum Messen der Masse oder des Gewichts von weichen Gegenständen, die in
eine Schwinganordnung einer Waschmaschine geladen sind, bevor die weichen Gegenstände
einer Behandlung durch die Waschmaschine unterzogen werden, welches die folgenden
Schritte aufweist:
- Erfassen einer relativen Verlagerung zwischen zwei Elementen des Schwingsystems,
wobei die zwei Elemente (3, 4) durch zwei Enden teleskopisch miteinander gekoppelt
sind, wobei ein erstes der zwei Enden ferromagnetisches Material aufweist und ein
zweites der zwei Enden eine Wicklung (9) aufweist, dadurch gekennzeichnet, dass
- ein elektronisches Modul (6), das zum Erfassen der relativen Verlagerung der Enden
der Elemente (3, 4) ausgelegt ist, am einen der zwei Elemente angeordnet ist und eine
Oszillationsschaltung (12) aufweist,
- eine Oszillationsfrequenz einer Oszillatorschaltung (12) erfasst wird, wobei die
Oszillationsfrequenz von der Impedanz der Wicklung (9) abhängig ist, welche an einem
der zwei Elemente angeordnet ist,
- wobei die relative Verlagerung als Funktion der Oszillationsfrequenz bestimmt wird.
12. Verfahren nach Anspruch 11, dadurch gekennzeichnet, dass die relative Verlagerung auf der Basis von Information, gemessen von Sensormitteln,
in Bezug auf Betriebsparameter des Haushaltsgeräts bestimmt wird.
13. Verfahren nach Anspruch 11 oder 12, dadurch gekennzeichnet, dass relative Verlagerung auf der Basis von Information, die von einem zentralen Controller
des Haushaltsgeräts übertragen wird, in Bezug auf den Verschleiß des Haushaltsgeräts
bestimmt wird.
14. Verfahren nach einem der Ansprüche 11 bis 13, dadurch gekennzeichnet, dass es einen Kalibrierschritt aufweist, der ausgeführt wird, wenn die Schwinganordnung
leerläuft, zu dem Zweck, eine Leerlaufoszillationsfrequenz der Oszillatorschaltung
(12) zu erfassen.
1. Appareil électroménager permettant de traiter des matières textiles, en particulier,
machine à laver le linge, comportant :
- un ensemble à mouvement oscillant retenu, de façon élastique, à une structure au
moyen d'un système de suspension comprenant une paire d'éléments (3,4) couplés l'un
à l'autre de façon télescopique par leurs deux extrémités respectives, dans lequel
une première desdites deux extrémités comporte un matériau ferromagnétique et une
seconde des deux dites extrémités comporte une bobine (9), et
- un module de détection électronique (6) conçu pour détecter un déplacement relatif
des deux dites extrémités,
caractérisé en ce que ledit module électronique (6) est placé sur l'un des deux dits éléments (3,4) et
comporte un circuit d'oscillateur (12), dont la fréquence d'oscillation est fonction
de l'impédance de ladite bobine (9), et des moyens de traitement connectés fonctionnellement
au dit oscillateur et conçus pour mesurer ladite fréquence d'oscillation et pour déterminer,
en fonction de ladite fréquence d'oscillation, au moins une partie de l'information
qui peut être associée au dit déplacement relatif, ladite information étant la mesure
du volume ou du poids des matières textiles chargées dans ledit ensemble à mouvement
oscillant avant que lesdites matières textiles soient soumises à un traitement, en
particulier à un traitement de lavage.
2. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé en ce que ledit circuit d'oscillateur (12) est conçu pour générer un signal carré.
3. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé en ce que ledit oscillateur est un multivibrateur non stable.
4. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comporte des moyens de capteur connectés fonctionnellement au dit microcontrôleur
(16) et conçus pour détecter des paramètres de fonctionnement dudit appareil électroménager.
5. Appareil électroménager selon la revendication 4, caractérisé en ce que lesdits moyens de capteur comprennent un capteur de température (18), de préférence
un capteur du type NTC.
6. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il comporte un dispositif d'interface à travers lequel ledit appareil électroménager
communique ladite information à un utilisateur.
7. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé
en ce ladite bobine (9) est placée sur une extrémité du cylindre (3) d'un amortisseur
(1).
8. Appareil électroménager selon la revendication 7, caractérisé en ce que ladite extrémité comportant un matériau ferromagnétique est une extrémité d'un piston
(4) dudit amortisseur (1).
9. Appareil électroménager selon l'une quelconque des revendications précédentes, caractérisé
en ce ladite bobine (9) est placée sur une extrémité (41) du piston (4) d'un amortisseur
(1).
10. Appareil électroménager selon la revendication 9, caractérisé en ce que ladite extrémité (31) comportant un matériau ferromagnétique est une extrémité d'un
cylindre dudit amortisseur (1).
11. Procédé permettant de mesurer le volume ou le poids de matières textiles chargées
dans un ensemble à mouvement oscillant d'une machine à laver avant que lesdites matières
textiles ne soient soumises à un traitement par la machine à laver, comprenant les
étapes suivantes :
- détecter un déplacement relatif entre deux éléments du système à mouvement oscillant,
dans lequel lesdits deux éléments (3, 4) sont couplés ensemble de façon télescopique
par leurs deux extrémités, une première des deux dites extrémités comportant un matériau
ferromagnétique et la seconde des deux dites extrémités comportant une bobine (9),
caractérisé en ce qu'un module de détection électronique (6) conçu pour détecter le déplacement relatif
des extrémités desdits éléments (3, 4) est placé sur l'un des deux dits éléments et
comporte un circuit d'oscillateur (12),
- une fréquence d'oscillation d'un circuit d'oscillateur (12) est détectée, laquelle
fréquence d'oscillation est fonction de l'impédance de ladite bobine (9) placée sur
l'un des deux dits éléments,
- ledit déplacement relatif est déterminé en fonction de ladite fréquence d'oscillation.
12. Procédé selon la revendication 11, caractérisé en c que ledit déplacement relatif
est déterminé sur la base d'une information, mesurée par les moyens de capteur, se
rapportant à des paramètres de fonctionnement dudit appareil électroménager.
13. Procédé selon la revendication 11 ou 12, caractérisé en ce que ledit déplacement relatif est déterminé sur la base de l'information, transmise par
un contrôleur central dudit appareil électroménager, concernant l'usure dudit appareil
électroménager.
14. Procédé selon l'une quelconque des revendications 11 à 13, caractérisé par le fait de comporter une étape de calibrage, réalisée lorsque ledit ensemble à mouvement
oscillant est au repos, dans le but de détecter une fréquence d'oscillation au repos
dudit circuit d'oscillateur (12).