EP0250870A2

EP0250870A2 - Combined machine for washing and drying laundry

Info

Publication number: EP0250870A2
Application number: EP87107688A
Authority: EP
Inventors: Luigi Arreghini; Piero Durazzani
Original assignee: Industrie Zanussi SpA
Current assignee: Industrie Zanussi SpA
Priority date: 1986-06-26
Filing date: 1987-05-26
Publication date: 1988-01-07
Also published as: IT8645732A0; EP0250870A3; IT1192085B

Abstract

Combined machine of the domestic type comprising a tub (5) housing a rotatable drum (8) for containing laundry to be washed and dried. The drying section of the machine comprises a closed circuit including a blower (20) for circulating heated air through the laundry, and a condenser (22) provided with an open water flow circuit (27,28,29) for condensing the moisture extracted from the laundry.

The condenser (22) additionally cooperates with an open air-cooling circuit (30,31,32,33) for increasing the efficiency of the drying operation.

Description

The present invention relates to a combined machine of the domestic type for washing and drying laundry, and is directed in particular to a laundry washing and drying machine of the front-loading type comprising a tub and a drum rotatably mounted therein for containing the laundry during the washing and drying operations.
Machines of this type are already generally known and usually include a closed circuit for the drying air, in which the air is heated and recirculaetd through the laundry so as to entrain the moisture remaining therein at the end of the washing operation. The air thus entraining the moisture is caused to pass through a condenser, in which the air is cooled for precipitating the moisture therefrom, whereupon the air continues its circulation.
For enabling it to condense the moisture entrained by the drying air, the condenser is connecetd to an outlet of the water mains. The condensate is discharged via the discharge conduit of the machine with the aid of the discharge pump. Machines of this type are described for instance in German Patents 2,529,577, 2,806,873, and 2,852,449.
The main problem encountered with machines of this type derives from the low efficiency of the drying operation and from the demand for excessive amounts of water for increasing the efficiency of the condenser with a view to reducing the duration of a full operating cycle of the machine. The overall result is a considerable consumütion of energy which is in contrast to the official attitude in many countries to encourage the designers of electric household appliances to reduce the overall energy consumption of their products.
German Patent Application No. 30 09 954 proposes an improved machine of the above type permitting part of the thermal energy to be recuperated by the use of two countercurrent heat exchangers through which the drying air is successively directed.
The shortcomings of this solution are represented by the highly complicated construction of the machine and by its increased manufacturing costs, which are not compensated by the limited energy saving to be obtaiend thereby.
It is an object of the present invention to provide a combined machine for washing and drying laundry, including a drying section combining increased efficiency with a simplified construction as required for appliances for domestic use.
This object is attained in a combined machine of the domestic type for washing and drying laundry, comprising a tub with a rotatable drum mounted therein for containing the laundry during the washing and drying operations, a first liquid flow circuit including a discharge pump for discharging the washing liquid from the tub, and a closed drying circuit including a blower for circulating heated air through the laundry and a surface condenser of the air-to-water type supplied via a second liquid flow circuit connected on the one hand to the water mains and on the other, to said discharge pump, the machine being characterized in that said condenser is additionally connected to an open air-cooling circuit comprising a further blower.
Further 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 diagrammatic illustration of a machine according to the invention, and
fig. 2 shows an enlarged illustration of the front part of the machine shown in fig. 1.

A combined machine for washing and drying laundry according to the invention substantially comprises a housing 1 having a planar top cover 2, an instrument panel 3 carrying various control elements, and a door 4 closing the front wall of the housing.
Contained within housing 1 is a tub 5 provided with a counterweight 6 and connected to housing 1 by a bellows-type seal 7.
Mounted within tub 5 is a drum 8 having a perforate cylindrical peripheral wall internally provided with ribs 9 for entraining the laundry.
Drum 8 has a front access opening 10 in alignment with a similar opening 11 of tub 5. Openings 10 and 11 are closed by a bulleye-type door 12 hinged on housing 1.
Drum 8 is adapted to be rotated within tub 5 by the action of an electric motor 13 via a belt transmission 14.
Tub 5 is formed with a lower opening 15 connected via a conduit 16 to a discharge pump 17 and a discharge conduit 18 for discharging the washing and rinsing liquids at the end of the washing and rinsing operations, respectively. These operations are carried out in the fully conventional manner and, as far as described above with reference to the drawings, the machine does not represent any novelty over prior art as far as the construction and operation of its washing section is concerned.
The combined machine according to the invention further includes a drying section operable to circulate a current of heated air through the laundry contained in drum 8, so that the moisture contained in the laundry is extracted therefrom and subsequently condensed, the condensate being finally discharged from the machine.
To this purpose the machine is provided with a blower 20, electric heater elements 21, and a condenser 22 included in a closed circuit comprising an output conduit 23 from blower 20 to tub 5 and a return conduit 24 from condenser 22 to blower 20.
The air containing the moisture extracted from the laundry exits from drum 8 through a plurality of openings 25 formed in the lower portion of door 12. Openings 25 are connected to condenser 22 via a conduit 26.
Condenser 22 is a surface condenser of the air-to-water countercurrent type connected to the water supply mains via a conduit 27 provided with a solenoid valve 28, and on its discharge side to discharge pump 17 through a conduit 29
According to the invention, for increasing the efficiency of condenser 22 there is provided a second air circuit comprising an intake conduit 30 for the intake of ambient air, a blower 31 for directing the air towards condenser 22 via a further conduit 32, and a discharge conduit 33 for discharging the air to atmosphere.
According to a preferred embodiment as shown in fig. 2, condenser 22 is substantially formed of a circular helical winding of the drying air conduit 26 in surface contact with the cooling air conduit 32. The entry points of the two conduits 26 and 32 are disposed at opposite ends of the winding, so that the drying air, as represented by dotted arrows, flows through conduit 26 in a direction opposite to that of the cooling air flow through conduit 32 as represented by solid arrows.
The drying air conduit 26 has its lower portion suitably provided with ports 36 permitting the condensing water to escape towards conduit 29 (fig. 2).
The water supply conduit 27 directs a spray jet of cooling water into an end portion of the ascending section of conduit 26 so as to precipitate residual steam from the drying air before the latter enters the return conduit 24 towards blower 20. The cooling water subsequently descends by gravity along the walls of conduit 26 towards the lower portion of condenser 22 from where it escapes through conduit 29 towards discharge pump 17.
In the embodiment described, condenser 22 is disposed, by way of non-limitative example, on the inner face of the front wall of the housing of the machine, it being evident, however, that it may also occupy other positions within the machine in a modified embodiment of the invention.
The condenser may thus be positioned in the rear part of the machine, in which case drying air conduit 26 may pass below tub 5.
The section of the machine for carrying out the drying operation is thus formed as a closed circuit comprising blower 20 and condenser 22. The condensation of the moisture within condenser 22 is brought about by means of an open water flow circuit 27 - 29 and an open cooling air circuit 30 - 33.
Blowers 20 and 31 are advantageously driven by a single motor 34 to thereby simplify and rationalize the construction of the machine.
The motor 34 for driving the two blowers 20 and 31 is suitably connected to per se known and therefore not described devices for measuring the residual moisture of the laundry to thereby optimize the condensation of the moist air in the course of the drying operation and minimize the operating costs of the machine without resorting to increasing the supply of cooling water or to increasing the output of the heater element.
The connection of motor 34 to the devices for measuring the residual moisture of the laundry permits the rotational speed of blowers 20 and 31 to be varied in such a manner that in a range between predetermined maximum and minimum values of the residual moisture they are rotated at a speed which is inversely proportional to the degree of residual moisture of the laundry as determined in the course of the drying operation. This provision permits the operation of condenser 22 to be maintained at its highest level for the entire duration of the drying operation.
A further advantageous characteristic of the machine according to the invention is the provision of a stiffening collar 35 (fig. 2) inserted into bellows-type seal 7 at the side thereof facing towards tub 5. Collar 35 serves the purpose of ensuring the correct positioning of seal 7 adjacent front opening 10 of the drum.
Without the provision of this collar, seal 7 would be free to shift, permitting the drying air to escape and possibly resulting in undesirable frictional contact between seal 7 and the edge of opening 10 of drum 8.
The described laundry washing and drying machine is of course provided with all of the operating and control elements , such as a program control unit, thermostats, pressure switches and the like, conventionally employed in machines of this type and therefore not shown and described in detail.
The machine according to the invention may of course also be modified regarding for example the arrangement of its functional elements for adaptation to housings of different constructions, without thereby leaving the scope of protection of the described and claimed characteristics.

Claims

1. A combined machine of the domestic type for washing and drying laundry, comprising a tub housing a rotatable drum for containing the laundry during the washing and drying operations, a first liquid flow circuit including a discharge pump for discharging the washing liquid from said tub, and a closed drying circuit including a blower for circulating heated air through the laundry and a surface condenser of the air-to-water type supplied via a second liquid flow circuit connected on the one hand to the water supply mains and on the other, to said discharge pump, characterized in that said condenser (22) is additionally connected to an open air-cooling circuit (30,31,32,33) including a further blower (31).

2. A machine according to claim 1, in which the washing tub has a front wall provided with an opening for access to said drum, said opening being adapted to be closed by a bulleye-type door, characterized in that said condenser (22) is mounted on the inner side of said front wall of the machine (1), and connected via a conduit (26) to ports (25) formed in said door (12) for the passage of the drying air entraining moisture extracted from the laundry.

3. A machine according to claim 2, characterized in that said condenser (22) is mounted in the rear portion of the machine (1) in the space between the washing tub (5) and the outer housing (1) of the machine.

4. A machine according to claim 2, characterized in that said condenser (22) is formed of a cylindrical helical winding of said drying air conduit (26) in contact with a cooling air conduit (32), and in that the drying air flows through said condenser (22) in a direction opposite to that of the cooling air flow.

5. A machine according to claim 2, characterized in that said ports (25) formed in said door (25) are disposed circumferentially in the lower half of said door.

6. A machine according to claim 1, characterized in that said blower (20) of said closed drying air circuit and said further blower (31) of said open cooling air circuit are driven by a single electric motor (34).

7. A machine according to claim 1 and provided with known devices for measuring the residual moisture of the laundry, characterized in that said electric motor (34) for actuating said two blowers (20 and 31) is connected to said devices for measuring the residual moisture of the laundry for varying the rotational speed of said two blowers (20, 31) within a range between predetermined maximum and minimum values of the residual moisture at an inversely proportional rate to the measured residual moisture of the laundry.