[0001] The present invention relates to an electric household appliance.
[0002] More specifically, the present invention relates to an electric household appliance
corresponding to a home washing machine with a laundry drying device, or to a home
laundry tumble drier, to which the following description refers purely by way of example.
[0003] As is known, home tumble driers substantially comprise a parallelepiped-shaped casing;
a cylindrical laundry drying tub or chamber fixed horizontally inside the casing,
directly facing a laundry loading/unloading opening formed in the front face of the
casing; a door hinged to the front face of the casing to rotate to and from a work
position closing the opening in the front face to seal the drying tub; a cylindrical,
perforated-wall laundry drum housed to rotate axially inside the drying tub; and an
electric motor for rotating the laundry drum about its longitudinal axis inside the
drying tub.
[0004] Tumble driers of the above type also comprise a hot-air generator designed to circulate
inside the drying tub a stream of hot, low-moisture air, which, as it flows through
the laundry drum, flows over and rapidly dries the laundry inside the drum. More specifically,
the drier comprises a hot-air generator, in turn comprising a drying circuit connected
to the drying tub; a heating element, normally defined by a single electric resistor
located along the drying circuit to heat the air before it is fed into the drying
tub; and a ventilation device, comprising an intake fan rotated by the electric motor
to circulate the air inside the drying circuit.
[0005] As is known, users also need to be able to operate the drier at night, to take advantage
of lower nighttime energy rates, which obviously calls for a considerable reduction
in the noise level of the drier.
[0006] Patent Application
EP1564324A1, filed by the present Applicant, describes a drier featuring a memory containing
various "normal" user-selectable drying programs, each of which controls the motor
to rotate the fan and the drum at sufficiently high predetermined drying speeds; and
a user-selectable "night drying program", which operates the fan and the drum at "low"
rotation speed, i.e. lower than the "normal" drying program drying speeds, to reduce
the noise level of the fan and drum.
[0007] Though effective in terms of noise reduction, the drier in Patent Application
EP1564324A1 has various drawbacks. Reducing the rotation speed of the drum with respect to the
normal drying program drying speeds, in fact, results in poor distribution of the
laundry inside the drum, which tends to form into a ball, thus resulting, on the one
hand, in uneven drying of the laundry on the inside, and, on the other, in overheating
of the laundry on the outside.
[0008] DE 3820815 discloses a drum dryer in which laundry circulates due to a rotation of the washing
drum which is operated conjointly with a process air blower and through which hot
process air flows, the laundry may be circulated in a first drying section in alternate
directions or alternatively only in one direction in which the blower operates at
full load and be subjected to a flow of very hot process air in that one direction.
As a consequence, the operator has the choice if large laundry articles are to be
dried to prevent entanglement of the wash by alternating the direction of rotation
of the drum while on the other hand, if small laundry articles are to be dried, to
reduce the drying time and the energy consumption by using only one direction of rotation
of the drum.
[0009] It is an object of the present invention to provide an electric household appliance,
in particular a home laundry drier, which, on the one hand, implements a speed- and
noise-reducing "night drying program", and, on the other, provides for more efficient
drying of the laundry to eliminate the aforementioned drawbacks.
[0010] According to the present invention, there is provided an electric household appliance
as claimed in Claim 1 and, preferably, though not necessarily, in any one of the Claims
depending directly or indirectly on Claim 1.
[0011] A non-limiting embodiment of the present invention will be described by way of example
with reference to the accompanying drawings, in which:
Figure 1 shows a schematic side view of a tumble drier in accordance with the teachings
of the present invention;
Figure 2 shows a block diagram of the control circuit of the Figure 1 drier.
[0012] Number 1 in Figure 1 indicates as a whole an electric household appliance preferably
corresponding to a home laundry drier, which substantially comprises a preferably,
though not necessarily, parallelepiped-shaped casing 2; a laundry drum 3, which houses
the laundry for drying, and is housed in axially rotating manner inside casing 2,
in a preferably, though not necessarily horizontal position, directly facing a laundry
loading/unloading opening 2a formed in the front face of casing 2; a door 4 hinged
to the front face of casing 2 to rotate to and from a work position closing opening
2a in the front face to seal laundry drum 3; and a preferably, though not necessarily,
open-circuit hot-air generator 5 housed inside casing 2 and designed to circulate
inside laundry drum 3 a stream of hot, low-moisture air, which flows over and rapidly
dries the laundry inside the drum.
[0013] Drier 1 also comprises at least an electric motor 7 preferably a variable velocity
rotation motor or similar for rotating laundry drum 3 about its longitudinal axis
L, preferably, though not necessarily, inside a drying tub 6 housed inside casing
2. In the Figure 1 example, longitudinal axis L coincides with the longitudinal axis
L of drying tub 6.
[0014] With reference to Figure 1, hot-air generator 5 gradually draws air in from outside
laundry drum 3; heats the intake air to a predetermined temperature; and draws the
moisture-laden air out of laundry drum 3.
[0015] In other words, hot-air generator 5 continuously draws in, heats, and feeds outside
air into laundry drum 3 to rapidly dry the laundry inside the drum, and exhausts the
moisture-laden air from laundry drum 3 to the outside.
[0016] In the Figure 1 example, hot-air generator 5 comprises an air intake manifold 8 having
a first end connected to the rear wall of laundry drum 3, and a second end connected
to an air intake 9 formed preferably, though not necessarily, in casing 2; an electric
heating device 10 located preferably, though not necessarily, along intake manifold
8 to heat the airflow through intake 9; an exhaust manifold 11 connecting laundry
drum 3 to an exhaust outlet 12 in a wall of casing 2; and a centrifugal fan 13 located
preferably, though not necessarily, along exhaust manifold 11 to produce, inside intake
manifold 8 and exhaust manifold 11, a stream of air which flows through laundry drum
3 and over the laundry inside the drum, and is then exhausted to the outside.
[0017] Centrifugal fan 13 is connected by a transmission mechanism (shown by the dash line)
to electric motor 7, which rotates both fan 13 and laundry drum 3 about their respective
axes of rotation.
[0018] Casing 2, drying tub 6, laundry drum 3, and electric motor 7 are all parts commonly
used in the industry, and are therefore not described in detail.
[0019] With reference to Figures 1 and 2, heating device 10 comprises two or more passive
electric components 15, which dissipate electric power by Joule effect to heat the
air supply to laundry drum 3; and a control module 16 for controlling passive electric
components 15 to regulate the energy dissipated by passive electric components 15
in the form of heat by Joule effect.
[0020] More specifically, control module 16 controls electric motor 7 to rotate laundry
drum 3 in a first rotation direction D1 or a second rotation direction D2 opposite
first rotation direction D1, and controls passive electric components 15 to regulate
the electric power P
E dissipated by passive electric components 15 in the form of heat, so that the temperature
t of the air heated by passive electric components 15 assumes a first value t
1 when laundry drum 3 is rotated in the first rotation direction D1, or a second value
t
2, different from first value t
1, when laundry drum 3 is rotated in the second rotation direction D2.
[0021] More specifically, passive electric components 15 of heating device 10 comprise resistors
15 series- or parallel-connected to one another between two electric power lines 18
at respective reference voltages; and control module 16 comprises a number of switching
devices 19, each interposed between one of the two power lines 18 and a respective
resistor 15.
[0022] More specifically, in the Figure 2 example, heating device 10 comprises two resistors
15, each connected to a power line 18 via a respective switching device 19. More specifically,
the two resistors 15 may have different resistances, e.g. one of the two resistors
15 may have a higher resistance than the other.
[0023] Drier 1 also comprises an electronic control unit 20, which controls electric motor
7 to vary the rotation speed v and/or the rotation direction D of the drive shaft
7a of the motor, and controls control module 16 to regulate the energy dissipated
by resistors 15 and so vary the heat produced and, hence, the temperature t of the
air supply to drum 3.
[0024] More specifically, electronic control unit 20 comprises a memory unit 21 containing
a number of user-selectable drying programs, each comprising information indicating:
total drying cycle time DT; the rotation speed/s v of drum 3 during the drying cycle;
and the electric power supply P
E to resistors 15.
[0025] More specifically, the drying programs comprise at least one "low-noise drying program"
containing the following parameters : total drying program time DT; rotation time/s
of motor 7 in a first rotation direction D1; rotation time/s of motor 7 in a second
rotation direction D2 opposite to said first rotation direction D1; rotation speed
v1 of motor 7 in the first rotation direction D1; and rotation speed v2 of motor 7
in the second rotation direction D2.
[0026] Drier 1 also comprises an interface unit 22, which allows the user to select the
low-noise drying program from the various memorized drying programs, and so transmit
a signal to electronic control unit 20 to commence drying the laundry in accordance
with the low-noise program.
[0027] Drier 1 operates as follows. Following user selection of the low-noise drying program,
electronic control unit 20 sets switching devices 19 to a first configuration to dissipate
in heat a first electric power P
E=P
E1, and, at the same time, controls electric motor 7 to rotate drive shaft 7a of the
motor in first rotation direction D1 at a first slow rotation speed v=v1. More specifically,
the first rotation speed v1 of drive shaft 7a of electric motor 7 may be approximately
2000 rpm, and the first rotation direction of drive shaft 7a of electric motor 7 may
rotate laundry drum 3 clockwise (in Figure 2).
[0028] After a predetermined time ΔT1, e.g. about 60 seconds, electronic control unit 20
sets switching devices 19 to a second configuration to dissipate a second electric
power P
E2, lower than P
E1, and so lower the temperature t2<t1 of the air supply to drum 3, and, at the same
time, controls electric motor 7 to rotate drive shaft 7a of the motor in second rotation
direction D2 at a second slow rotation speed v2<=v1. More specifically, less than
2000 rpm, and the second rotation direction D2 of drive shaft 7a of electric motor
7 may rotate laundry drum 3 anticlockwise (in Figure 2).
[0029] More specifically, the first configuration of switching devices 19 activated by control
unit 20 may comprise closing a first switching device 19 to power a first resistor
15, and opening a second switching device 19 to zero heat generation by the second
resistor 15; and the second configuration of switching devices 19 may comprise closing
the second switching device 19 to power the second resistor 15, and opening the first
switching device 19 to zero Joule heat generation by the first resistor 15.
[0030] It should be pointed out that the change in the rotation direction of drum 3 in the
low-noise drying program conveniently prevents balling of the laundry, by distributing
it on the inner wall of drum 3 and so enabling uniform drying; while the reduction
in Joule heat generated as the drum rotates in second rotation direction D2, i.e.
after the laundry is distributed on the inner wall of laundry drum 3, reduces the
air temperature t2<t1, and so greatly reduces the risk of overheating the laundry
inside drum 3.
[0031] After a predetermined time ΔT2, the low-noise drying cycle may either terminate the
drying cycle or repeat the above steps, i.e. alternate rotation directions D1 and
D2 and/or relative rotation speeds v1 and v2 of motor 7 for predetermined times ΔTi.
[0032] The drier as described above is extremely advantageous, by not only ensuring a low
noise level, but also preventing balling and, at the same time, overheating and possible
damage, of the laundry.
[0033] Clearly, changes may be made to electric household appliance 1 as described herein
without, however, departing from the scope of the present invention as defined in
the accompanying Claims.
1. An electric household appliance (1) comprising a casing (2); a revolving laundry drum
(3), which houses laundry for drying, and is mounted for rotation about its longitudinal
axis (L) inside said casing (2); hot-air generating means (5) for circulating a stream
of hot air inside the laundry drum (3); electric drive means (7) for rotating said
laundry drum (3) about said longitudinal axis (L); electric heating means (10) for
dissipating in the form of heat a given electric power (PE) to heat the air supply
to the laundry drum (3) to a given temperature (t); electronic control means (20),
which control said electric drive means (7) to rotate said laundry drum (3) in a first
rotation direction (D1) or a second rotation direction (D2) opposite said first rotation
direction (D1), and control said electric heating means (10) to regulate the electric
power (PE) dissipated in heat by the electric heating means, so that the temperature
(t) of the air heated by said electric heating means (10) assumes a first value (t1)
when said laundry drum (3) rotates in said first rotation direction (D1), or a second
value (t2), lower than the first value (t1),
when the laundry drum (3) rotates in said second rotation direction (D2), characterized in that the electronic control means (20) control said electric drive means (7) to rotate
said laundry drum (3) in said first rotation direction (D1) at a predetermined first
rotation speed (v1), or in said second rotation direction (D2), opposite said first
rotation direction (D1), at a predetermined second rotation speed (v2) lower than
the first rotation speed (v1).
2. An electric household appliance as claimed in Claim 1, wherein said electric heating
means (10) comprise at least two resistors (15).
3. An electric household appliance as claimed in Claim 2, wherein one of the two resistors
(15) has a different resistance from the other resistor (15).
4. An electric household appliance as claimed in Claim 2 or 3, wherein said electric
heating means (10) comprise at least two switching devices (19), each connected between
a respective resistor (15) and an electric power line (18).
5. An electric household appliance as claimed in Claim 1, wherein said electronic control
means (20) selectively close/open said switching devices (19) to activate/deactivate
the corresponding resistors (15).
6. An electric household appliance as claimed in any one of the foregoing Claims, wherein
said electric drive means is an electric motor (7).
7. An electric household appliance as claimed in Claim 6, wherein said electric motor
(7) is a variable velocity rotation motor.
1. Elektrisches Haushaltsgerät (1), das Folgendes umfasst: ein Gehäuse (2); eine drehende
Wäschetrommel (3), die Wäsche zum Trocknen aufnimmt und die innerhalb des Gehäuses
(2) zum Drehen um ihre Längsachse (L) montiert ist; Heißluft erzeugende Mittel (5),
zum Zirkulieren eines Stroms heißer Luft innerhalb der Wäschetrommel (3); elektrische
Antriebsmittel (7) zum Drehen der Wäschetrommel (3) um die Längsachse (L); elektrische
Heizmittel (10) zum Umsetzen einer gegebenen elektrischen Leistung (PE) in Form von
Wärme, um die Luftzufuhr zu der Wäschetrommel (3) auf eine gegebene Temperatur (t)
zu heizen; elektronische Steuerungsmittel (20), die die elektrischen Antriebsmittel
(7) steuern, die Wäschetrommel (3) in einer ersten Drehrichtung (D1) oder einer zweiten,
der ersten Drehrichtung (D1) entgegengesetzten Drehrichtung (D2) zu drehen, und die
elektrischen Heizmittel (10) zu steuern, die von den elektrischen Heizmitteln in Wärme
umgesetzte elektrische Leistung (PE) so zu steuern, dass die Temperatur (t) der von
den elektrischen Heizmitteln (10) geheizten Luft einen ersten Wert (t1), wenn sich
die Wäschetrommel (3) in der ersten Drehrichtung (D1) dreht, oder einen zweiten Wert
(t2), der kleiner als der erste Wert (t1) ist, annimmt, wenn sich die Wäschetrommel
(3) in der zweiten Drehrichtung (D2) dreht, dadurch gekennzeichnet, dass die elektronischen Steuerungsmittel (20) die elektrischen Antriebsmittel (7) steuern,
die Wäschetrommel (3) in der ersten Drehrichtung (D1) mit einer vorbestimmten ersten
zweiten Drehgeschwindigkeit (v1) oder in der zweiten, der ersten Drehrichtung (D1)
entgegengesetzten Drehrichtung (D2) mit einer vorbestimmten zweiten Drehgeschwindigkeit
(v2), die kleiner als die erste Drehgeschwindigkeit (v1) ist, zu drehen.
2. Elektrisches Haushaltsgerät nach Anspruch 1, wobei die elektrischen Heizmittel (10)
mindestens zwei Widerstände (15) umfassen.
3. Elektrisches Haushaltsgerät nach Anspruch 2, wobei einer der zwei Widerstände (15)
einen anderen Widerstandswert aufweist als der zweite Widerstand (15).
4. Elektrisches Haushaltsgerät nach Anspruch 2 oder 3, wobei die elektrischen Heizmittel
(10) mindestens zwei Schaltvorrichtungen (19) umfassen, wobei jede zwischen einen
jeweiligen Widerstand (15) und eine elektrische Stromleitung (18) geschaltet ist.
5. Elektrisches Haushaltsgerät nach Anspruch 1, wobei die elektronischen Steuerungsmittel
(20) die Schaltvorrichtungen (19) selektiv schließen/öffnen, um die jeweiligen Widerstände
(15) zu aktivieren/deaktivieren.
6. Elektrisches Haushaltsgerät nach einem der vorhergehenden Ansprüche, wobei die elektrischen
Antriebsmittel ein Elektromotor (7) sind.
7. Elektrisches Haushaltsgerät nach Anspruch 6, wobei der Elektromotor (7) ein Motor
mit variabler Drehgeschwindigkeit ist.
1. Appareil ménager électrique (1) comprenant une enceinte (2) ; un tambour à linge rotatif
(3), qui reçoit du linge à sécher, et est installé en vue de sa rotation autour de
son axe longitudinal (L) à l'intérieur de ladite enceinte (2) ; des moyens de génération
d'air chaud (5) servant à faire circuler un courant d'air chaud à l'intérieur du tambour
à linge (3) ; des moyens d'entraînement électriques (7) servant à faire tourner ledit
tambour à linge (3) autour dudit axe longitudinal (L) ; des moyens de chauffage électriques
(10) servant à dissiper sous forme de chaleur une puissance électrique (PE) donnée
afin de chauffer l'alimentation en air du tambour à linge (3) jusqu'à une température
(t) donnée ; des moyens de commande électroniques (20), qui commandent lesdits moyens
d'entraînement électriques (7) de façon à ce qu'ils fassent tourner ledit tambour
à linge (3) dans une première direction de rotation (D1) ou une seconde direction
de rotation (D2) opposée à ladite première direction de rotation (D1), et commandent
lesdits moyens de chauffage électriques (10) de façon à ce qu'ils régulent la puissance
électrique (PE) dissipée en chaleur par lesdits moyens de chauffage électriques, de
telle sorte que la température (t) de l'air chauffé par lesdits moyens de chauffage
électriques (10) prenne une première valeur (t1) lorsque ledit tambour à linge (3)
tourne dans ladite première direction de rotation (D1), ou une seconde valeur (t2),
inférieure à la première valeur (t1), lorsque le tambour à linge (3) tourne dans ladite
seconde direction de rotation (D2), caractérisé en ce que les moyens de commande électroniques (20) commandent lesdits moyens d'entraînement
électriques (7) de façon à ce qu'ils fassent tourner ledit tambour à linge (3) dans
ladite première direction de rotation (D1) à une première vitesse de rotation (v1)
prédéterminée, ou dans ladite seconde direction de rotation (D2), opposée à ladite
première direction de rotation (D1), à une seconde vitesse de rotation (v2) prédéterminée
inférieure à la première vitesse de rotation (v1).
2. Appareil ménager électrique selon la revendication 1, dans lequel lesdits moyens de
chauffage électriques (10) comprennent au moins deux résistances (15).
3. Appareil ménager électrique selon la revendication 2, dans lequel l'une des deux résistances
(15) présente une résistance différente de celle de l'autre résistance (15).
4. Appareil ménager électrique selon la revendication 2 ou 3, dans lequel lesdits moyens
de chauffage électriques (10) comprennent au moins deux appareils de connexion (19),
chacun connectés entre une résistance (15) respective et une ligne électrique (18).
5. Appareil ménager électrique selon la revendication 1, dans lequel lesdits moyens de
commande électroniques (20) ferment/ouvrent, de manière sélective, lesdits appareils
de connexion (19) de façon à activer/désactiver les résistances (15) correspondantes.
6. Appareil ménager électrique selon l'une quelconque des revendications précédentes,
dans lequel lesdits moyens d'entraînement électriques sont un moteur électrique (7).
7. Appareil ménager électrique selon la revendication 6, dans lequel ledit moteur électrique
(7) est un moteur de rotation à vitesse variable.