COMBINED LAUNDRY WASHING AND DRYING MACHINE

Abstract: A laundry washing and drying machine of the front-loading type for domestic use, comprising a tub (4) rotatably mounting a drum (9) adapted to contain the laundry during the washing and drying operations. The drying section of the machine comprises a fan (25) for directing hot air into contact with the laundry through an opening (28) in the top wall of the tub, and deflector means (34, 37, 39) for deviding the major part of the hot air flow into a first and second flow, directed respect­ ively towards openings (38) formed in the front wall (11) of the drum and towards the loading opening (14) of the drum, a remaining part of the hot air being permitted to diffuse in a homo­ genuous manner between the drum and the tub. The machine is also provided with means (40, 41) for maintaining a passage for the supply of the hot air to the tub in an unobturated state.

Description: The present invention relates to a combined laundry washing and drying machine. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Second deflector lip 39 thus directs a second hot air flow towards the center of the laundry charge contained in drum 9. 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. 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. 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. 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. 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. 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. 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. 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. 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). 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. 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. 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.

Claims: 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). 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). 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.

Inventors: REGAZZO, OLINDO
Applicants: INDUSTRIE ZANUSSI S.P.A.
Application year: 1987
Main classification: D06F25
IPC codes: D06F39, D06F25, D06F58