[0001] The present invention relates to a combined laundry washing and drying machine.
[0002] In particular, the invention relates to an electric household appliance of the front-loading
type comprising a tub in which a drum adapted to contain the laundry during the washing
cycle as well as during the drying cycle is mounted for rotation about a horizontal
axis.
[0003] Already known are combined laundry washing and drying machines in which the laundry
is washed by being immersed into the washing liquid and/or by being sprayed with reduced
amounts of the washing liquid recirculated through the tub, and in which the laundry
is subsequently dried with the aid of heated air.
[0004] The drying process may be carried out with a closed air flow path in which a forced
air flow is circulated through a heating device, the drum containing the laundry,
and a dehumidifying device, as described for instance in Italian Patent Application
No. 45718, filed on April 9, l986 by the present applicant, or with an open air flow
circuit in which ambient air is aspirated, heated, brought into contact with the laundry,
and discharged from the machine in a moist and hot state, as described in IT-PS No.
1,045,582.
[0005] In combined machines of this type, the heated drying air is brought into contact
with the laundry only through the front opening of the drum, as described for instance
in German Patent Application No. l,585,675, or is directed through a single opening
formed in the tub so as to pass through the cylindrical outer wall of the drum in
a radial direction, as decribed for instance in German Patent Application No. 2,306,873.
[0006] These two systems for the introduction of the hot drying air present considerable
problems as regards the construction of the machine and the homogenous distribution
of the hot drying air within the drum.
[0007] In particular, the introduction of the hot drying air through the front opening of
the drum has resulted in a complicated construction of the machine, as it requires
the provision of hermetically sealed conduit means for conveying the heated drying
air from the heating device to the opening of the drum, as described for instance
in Italian Patent Application No. 68887 A/78.
[0008] Another disadvantageous aspect of this solution is due to the fact that the thorough
drying of the laundry at locations farther away from the opening of the drum results
in the laundry more closely adjacent the air entrance opening being excessively dried
and in danger of being damaged thereby.
[0009] As regards the second-named system for the introduction of the heated air, in which
the air solely impinges on the peripheral wall of the drum, the result is a very slow
and thus expensive drying process, since the drying effect is mainly obtained by the
migration of the moisture from the center towards the peripheral layers of the laundry,
and only to a very small degree by direct contact of the laundry with the drying air
flow.
[0010] For obtaining a good result of the drying process it is indispensable, however, that
the hot air flow sweeps the greatest possible surface area of the moist laundry, and
that the water vapour is mainly carried away by the movement of the hot air.
[0011] It is also to be noted that in certain laundry washing and drying machines, particularly
ones in which the laundry is washed by being sprayed with reduced amounts of a recirculated
washing liquid, the washing program provides one or more spin-drying steps in the
course of the washing process.
[0012] These spin-drying steps result in the formation of substantial amounts of foam which
may then enter and thereby obturate the drying air supply conduit.
[0013] This shortcoming may be remedied by the provision of electronic components for interrupting
the energization of the motor as soon as the drum attains the required rotational
speed, or by the provision of non-return valve means for preventing the escape of
fluids from the laundering tub. Such additional provisions however result in complicating
the control circuitry of the machine.
[0014] It is thus a main object of the invention to provide a laundry washing and drying
machine in which the disadvantages regarding the distribution of the hot air within
the drum as described above are eliminated to thereby optimize the drying process
and simplify the construction of the machine.
[0015] A further object of the invention is to prevent in a simple and efficient manner
the obturation of the hot drying air supply conduit by the foam formed during the
washing process.
[0016] These objects are attained in a combined laundry washing and drying machine, particularly
of the front-loading type and for domestic use, comprising a tub in which a drum adapted
to contain the laundry during the washing cycle as well as during the drying cycle
is mounted for rotation about a horizontal axis, a drying air flow circuit including
a fan for directing dried and heated air into contact with the laundry via conduit
means provided with heater elements and opening through a top wall of the tub adjacent
a front wall of the drum, the heated and moist air being discharged from the tub through
a further opening thereof, wherein the hot air flow exiting from the opening in the
top wall of the tub is directed into the interior of the tub by deflector means effective
to devide the major part of the air flow into a first flow directed towards through-openings
formed in the front wall of the drum, and a second flow directed towards the upper
boundary of the front-loading opening of the drum, the remaining part of the hot
air flow being permitted to diffuse between the tub and the drum.
[0017] The objects and characteristics of the invention will become more clearly evident
from the following description, given by way of example with reference to the accompanying
drawings, wherein:
fig. 1 shows a diagrammatical illustration of a preferred embodiment of the machine
according to the invention, and
fig. 2 shows an enlarged detail of a front portion of the machine shown in fig. 1.
[0018] A combined laundry washing and drying machine according to the invention has an outer
housing 3 enclosing a tub 4 provided with a counterweight 5 and having a front opening
6 aligned with a front opening 7 of housing 3 and connected thereto by a bellows-type
seal 8.
[0019] Mounted in tub 4 for rotation about a horizontal axis is a drum 9 having a cylindrical
outer wall 10 formed with through-openings 13, a front wall 11 and a rear wall 12,
as well as per se known and therefore not described ledge elements for entraining
the laundry.
[0020] Drum 9 is adapted to be rotated by an electric motor and a per se known and therefore
not shown belt transmission, and is formed with a front loading opening 14 aligned
with front openings 6 and 7 of tub 4 and housing 3, respectively.
[0021] Front opening 7 of housing 3 is provided with a door 15 made of a transparent material
such as glass or plastics and hinged to housing 3.
[0022] Laundering tub 4 has a bottom opening 16 connected via a conduit 17 and a filtering
device 18 to a discharge pump 19 and a conduit 20 for discharging the washing liquid
from the machine at the end of the washing and rinsing cycles. The machine according
to the invention is adapted to carry out in a per se known manner a laundering process
by immersion of the laundry, or a washing process by spraying the laundry with a reduced
amount of a continuously recirculated washing liquid.
[0023] To this purpose filtering device 18 is connected via a conduit 21, a collecting receptacle
22 and a recirculation pump 23 to a conduit 24 extending through a top wall of tub
4 for spraying the laundry contained in drum 9 with jets of the washing liquid.
[0024] The machine according to the invention also includes a forced air-flow drying system
in which heated air is caused to flow through drum 9 with the moist laundry contained
therein, the air being subsequently dehumidified and recirculated.
[0025] To this purpose there is provided a fan 25 having its intake connected to a rear
opening 26 of tub 4 via a water-cooled condenser device 27, the outlet side of fan
25 being connected to a top opening 28 of tub 4 via a conduit 29 containing electric
resistance heater elements 30.
[0026] Condenser device 27 is of a known type and connected via a conduit 31 and a solenoid
valve 32 to the water supply mains for supplying the water required for cooling condenser
device 27 via conduit 31 and an associated spray nozzle 33.
[0027] The heated drying air exiting from top opening 28 of tub 4 is subsequently directed
towards drum 9 for entraining the moisture from the laundry contained therein.
[0028] According to the invention, the flow path of the heated drying air exiting from opening
28 is not defined as in known machines by hermetically sealed conduit means, but is
advantageously established by a suitable design of already existing components immediately
required for the operation of the machine.
[0029] As shown in fig. 2, a first deflector lip 34 of adequate rigidity is integrally formed
with a seal 35 disposed between conduit 29 and tub 4 so as to deflect the hot air
flow towards the front wall 36 of tub 4 as indicated by arrows.
[0030] At this location front wall 36 of tub 4 is formed with a recess 37 adapted to receive
the hot air provenient from deflector lip 34 and to direct a first hot air flow towards
front wall 11 of drum 9 suitably formed with through-openings 38.
[0031] The hot drying air bypassing openings 38 approaches the upper boundary of front opening
14 of drum 9 and is deflected into drum 9 by a second deflector lip 39 of adequate
rigidity integrally formed with the upper half of bellows-type seal 8.
[0032] Second deflector lip 39 thus directs a second hot air flow towards the center of
the laundry charge contained in drum 9.
[0033] The advantages arising from the shape and positioning of second deflector lip 39
are mainly due to the fact that the hot air flow deflected thereby is capable of diffusing
in the interior of drum 9 so as to sweep the greatest possible surface area of the
laundry, and not only a small proportion thereof.
[0034] Second deflector lip 39 has the further advantageous effect of protecting bellows-type
seal 8 and door 15 from direct contact with the hot air, so that specifically door
15 is prevented from becoming heated to a temperature at which the laundry might be
singed or the user might sustain burns on contact therewith.
[0035] Deflector lips 34 and 39 may of course be formed in a different manner, for instance
by extending and suitably shaping the top wall and front wall 36 of tub 4, or even
by the employ of separate components.
[0036] In the course of laboratory tests it has been found that the provision of deflector
means 34, 37 and 39 and the elimination of hermetically sealed hot air conduit means
permit the overall efficiency of the machine during the drying process to be optimized.
[0037] As a matter of fact, not all of the hot air exiting from opening 28 is received by
recess 37 and second deflector lip 39, part of it being permitted to diffuse between
tub 4 and drum 9 to thereby establish a unifoem temperature within tub 4 and thus
within the laundry charge.
[0038] The hot air flows deflected by recess 37 and deflector lip 39 are directly received
by the moist laundry charge to result in a successive movement of the hot and moist
air from the interior to the exterior of drum 9.
[0039] In the machine according to the invention, the indispensable conditions are thus
established for obtaining a good result of the drying process, by ensuring that the
hot air sweeps the greatest possible surface area of the laundry and the hot and moist
air is caused to move from the interior to the exterior of drum 9.
[0040] It is to be noted that the program of laundry washing and drying machines operating
on the recirculation principle including spraying the laundry with the washing liquid
provides for the execution of one or more spin-drying steps during the washing cycle.
This may lead to the formation of substantial amounts of foam capable of entering
and thereby obturating the drying air supply conduit.
[0041] A further advantageous aspect of the machine according to the invention is therefore
the provision of an anti-foam feature obtained by suitable subdividing the output
of recirculation conduit 24 (fig. 1).
[0042] In particular, recirculation conduit 24 is provided with a first and a second soray
nozzle 40 and 41, respectively, for spraying the washing liquid onto cylindrical wall
10 of drum 9 and towards hot air entrance opening 28, respectively.
[0043] First nozzle 40 is effective in a per se known manner to spray the washing liquid
onto the laundry through perforations 13 of drum 9, while second nozzle 41 acts to
abate the foam formed during the spin-drying steps for maintaining the hot air supply
passage between drum 9 and tub 4 free of obturation.
[0044] The described laundry washing and drying machine may of course be provided with any
of the operating and control elements (program control unit, thermostats, pressure
switches etc.) usually employed in machines of this type and therefore not requiring
any specific description. The machine according to the invention may also be modified,
be it with regard to the arrangement of its functional elements, such as fan 25 or
condenser 27, or with regard to the construction of the drying circuit, which may
be of the condenser-equipped closed type or of the ambient-air open type, without
thereby leaving the scope of protection of the characteristics described and claimed.
1. A combined laundry washing and drying machine, particularly of the front-loading
type and for domestic use, comprising a tub in which a drum adapted to contain the
laundry during the washing cycle as well as during the drying cycle is mounted for
rotation about a horizontal axis, a drying air flow circuit including a fan for directing
dried and heated air into contact with the laundry via conduit means provided with
heater elements and opening through a top wall of said tub adjacent the front wall
of said drum, the heated and moist air being discharged from said tub through a further
opening thereof, characterized in that the hot drying air flow exiting from said opening
(28) in said top wall of said tub (4) is directed into the interior of said tub (4)
by deflector means (34, 37, 39) effective to devide the major part of said air flow
into a first flow directed towards through-openings (38) formed in said front wall
(11) of said drum (9), and a second flow directed towards the upper boundary of the
front-loading opening (14) of said drum (9), the remaining part of said hot air being
permitted to diffuse between said tub (4) and said drum (9).
2. A machine according to claim 1, characterized in that said deflector means (34,37,39)
comprise a first deflector lip (34) disposed adjacent said opening (28) in said top
wall of said tub (4) and adapted to deflect said hot air flow towards the front wall
(36) of said tub (4), a recess (37) formed in said front wall (36) of said tub (4)
and adapted to receive the hot air provenient from said first deflector lip (34) and
to direct said first air flow towards said front wall (11) of said drum (9) provided
with said through-openings (38), and a second deflector lip (39) formed adjacent the
top half of a bellows-type loading opening seal (8) and adapted to receive the hot
air bypassing said openings (38) of said drum (9) for directing said second hot air
flow towards said upper boundary of said front opening (14) of said drum (9).
3. A machine according to claims 1 and 2, comprising a recirculation system for recirculating
the washing liquid from a lower portion of said tub to a top portion thereof to thereby
spray the laundry with a reduced amount of said washing liquid, characterized in that
a conduit (24) for the recirculation of said washing liquid towards the top portion
of said tub (4) branches into a first and a second branch provided respectively with
a first spray nozzle (40) directed onto the cylindrical outer wall (10) of said drum
(9), and a second spray nozzle (41) directed towards said hot air entrance opening
(28) for maintaining the hot drying air flow path between said entrance opening (28)
and said front opening (14) of said drum (9) in an unobstructed state.