GB2294697A

GB2294697A - Clothes washing-drying machine with anti-foam phase

Info

Publication number: GB2294697A
Application number: GB9521678A
Authority: GB
Inventors: Silvano Cimetta
Original assignee: Electrolux Zanussi Elettrodomestici SpA
Current assignee: Electrolux Zanussi Elettrodomestici SpA
Priority date: 1994-09-19
Filing date: 1995-10-23
Publication date: 1996-05-08
Anticipated expiration: 2015-10-23
Also published as: FR2726583B1; GB2294697B; WO1996009260A1; JPH08206385A; ES2149642A1; ES2149642B1; AU1386395A; GB2294697A8; IT1267593B1; DE29516998U1; GB9521678D0; ITPN940065A0; ITPN940065A1; FR2726583A1

Abstract

A clothes washing-drying machine provided with a washing tub (1), a drum (2) which rotates within the tub and which is capable of containing the articles to be washed and rotating at different speeds including the spin speed, a discharge conduit (5) disposed below said tub, a circuit for circulating the drying air which is made up at least by a first conduit (6) for drawing in moist air from the interior of the tub, an impeller (7) for circulation of said drying air, a heating element (8) for said drying air and a conduit (9) for re-introducing said air into said tub wherein after the washing phase and before the rinsing phase said impeller (7) for circulating the hot air is activated automatically for a predetermined period of time (T). <IMAGE>

Description

CLOTHE8 WASHING-DRYING MACHINE WITH ANTI-FOAM PHASE The invention relates to a combined machine for washing and drying laundry which is provided with improved means for automatically eliminating possible accumulations of foam which have overflowed into the circuit for circulation of the drying air.

Combined machines for washing and drying laundry are known which involve their mode of operation being controlled by means for programming the operating cycle, which normally comprises, at the end of the washing phase, one or more laundry rinsing phases.

It has been found that, under particular conditions of operation, for example when the load of detergent substances is excessive but in particular with the use of detergent substances which produce particularly large amounts of foam, excessive foam production occurs within the tub, and, due to the alternative effect of the drum, the foam produced tends to penetrate into all the accessible cavities in the tub. Particularly in combined machines for washing and drying, the excess of foam tends to penetrate into the circuit for recirculation of the hot moistened air, in both the openings with which said recirculation circuit is connected to the interior of the tub and, in more serious cases, it clogs that circuit with a substantial amount of foam which naturally also includes bits of dirt which are removed from the laundry.

That circumstance gives rise to two types of problems which are described hereinafter: the first problem arises out of the fact that the excess foam, by blocking off all the openings, in fact makes the tub into a sealed container; in that way, when, after the washing phase, the rinsing phases are performed, thus using the appropriate respective amount of water, the tub is slightly pressurised since the amount of water introduced is not compensated by an equivalent volume of air expelled, not even by way of the conduit for the intake of water since the upper layer of foam which floats on the water rises with the level of the latter and thus very quickly blocks off the actual water intake conduit, permitting the intake of water but preventing the expulsion of air.

That means that the pressure sensor signals a pressure higher than that corresponding to the actual level of rinsing water introduced and consequently prematurely shuts off the intake flow of water, with easily imaginable disadvantages.

That problem has been overcome in the machines which are operable only for washing but not for drying by disposing suitable large vent conduit between the top of the tub and the water distribution means disposed thereabove; however that solution cannot be applied to a clothes washing-drying machine of the type described since during the drying operation that conduit would behave like a path for escape to the exterior of the hot air which is introduced by force into the tub.

In washing-drying machines therefore the problem has been confronted by providing a conduit for venting the seat of the impeller directly into said water distribution means, that conduit permitting venting but, because of its length, never becoming completely filled with foam which can overflow to the exterior.

However that design does not avoid the problem of pressurisation of the tub if the foam clogs the conduit for drawing in the drying air.

The second of the two problems involved is that, in the successive rinsing and spin phases, when the recirculation circuit is not functionally involved, the foam remains in that circuit even after the final spin of the laundry and before the drying phase.

It thus happens that, in the subsequent drying phase, when the flow of drying air passes through the circuit for recirculation and heating of air whose humidity is condensed, the foam present in the air recirculation circuit is retransported from the circuit into the tub again and irreversibly contaminates the laundry since the dirt and other substances present in the foam can no longer be removed from the laundry.

It would thus be desirable, and this is the aim of the present patent, to be able to provide a combined machine for washing and drying laundry, which is capable of eliminating the problems described by freeing the air circulation circuit from the foam which is possibly present, using simpler and more reliable methods, employing components which are already present and involving available technologies.

According to the present invention, there is provided a combined machine for washing and drying laundry, provided with a washing tub, a drum which, in use, rotates within said tub and which is capable of containing the articles to be washed and which is capable of rotating at different speeds including the spin speed, a discharge conduit disposed below said tub, and a circuit for circulation of the drying air which is made up at least by a first conduit for drawing in moist air from the interior of the tub, an impeller for circulation of said drying air, a heating element for said drying air and a conduit for re-introducing said air into said tub, said machine being capable of performing at least one washing cycle comprising at least one rinsing phase subsequent to the washing phase, wherein the machine is arranged to operate such that after said washing phase and before said rinsing phase said impeller for circulating the hot air is activated for a predetermined period of time.

The invention will be better appreciated from the following description given solely by way of non-limiting example and with reference to the accompanying drawing which is a diagrammatic view of the various components involved in the invention in a combined machine for washing and drying the laundry.

Referring to the single Figure showing a preferred embodiment, illustrated therein is a solution according to the invention and the operating principle thereof.

In the course of the subsequent description the term "water" will be used without discrimination also to denote rinsing water or washing solution, but that simplification will not compromise the clarity of the description, having regard to the context in which such terms are used, as will be readily apparent to the man skilled in the art.

The combined machine described has a washing tub 1, a drum 2 which rotates within the washing tub and which is capable of containing the articles 3 to be washed and a motor (not shown) which is connected to said drum and which is capable of causing it to rotate at variable preselectable speeds.

Even if they are not shown, consideration is also to be given to all the other elements which are known in the state of the art, which contribute to determining the conditions for correct operation of the machine.

Disposed below the tub is a discharge conduit 5 which is arranged substantially vertically and which communicates at the top with the interior of the tub, and with a discharge pump (not shown) at its lower end.

The machine is also provided with a circuit for circulating the drying air which, in the illustrated example, consists of at least one first conduit 6 for drawing in moist air from the interior of the tub, an impeller 7 for circulation of said drying air, a heating element 8 for said drying air and a conduit 9 for reintroducing said air into said tub.

In the example described the chamber of the impeller 7 is connected by means of a conduit 10 to said means 11 for distributing the water, which can be freely vented to the exterior.

That machine is capable of performing at least one washing cycle comprising at least one rinsing phase subsequent to the washing phase; during the washing phase the foam generated in the interior of the tub can penetrate deeply into the circuit for recirculation of the drying air from both the openings corresponding to the intake conduit 6 and to the conduit 9 for re-introduction of the air, due to the effect of the alternating movement of the drum, as well as the excessive production of foam, and remains there even after the rinsing phases, with the above-mentioned disadvantages.

To avoid that phenomenon the invention teaches using immediately after the end of the washing operation and for a brief period of time the impeller 7 for circulation of the air in the drying conduit, in such a way that the flow of air is established within the conduit, pulling away the foam by re-introducing it into the tub, thus completely removing any traces of foam from that circuit.

It has been observed in experiment that the passage of foam within that circuit for a brief period of time does not give rise to any problems in regard to the components which are to be found therein, such as the condenser, the impeller and the heating element 8.

That operation therefore, by freeing the intake conduit 6 and the re-introduction conduit 9, provides that, even when foam is present, the tub is freely vented, permitting the loading of the proper amount of water; in addition removing foam from the conduits ensures that the subsequent drying phase takes place in the total absence of foam.

Preferably such activation of the impeller 7 should be effected at least after a first emptying of water from the tub, in such a way as to limit the presence in the tub of foam which could be caused to circulate, together with the air which has been drawn in and blown within said circuit.

It has finally been found that the period of activation of the impeller should be maintained in domestic machines in a range of between 2 and 5 minutes; this is for the purpose of ensuring effective cleaning of the circuit without penalising the cycle with an excessive increase in duration.

Claims

1. A combined machine for washing and drying laundry, provided with a washing tub, a drum which, in use, rotates within said tub and which is capable of containing the articles to be washed and which is capable of rotating at different speeds including the spin speed, a discharge conduit disposed below said tub, and a circuit for circulation of the drying air which is made up at least by a first conduit for drawing in moist air from the interior of the tub, an impeller for circulation of said drying air, a heating element for said drying air and a conduit for re-introducing said air into said tub, said machine being capable of performing at least one washing cycle comprising at least one rinsing phase subsequent to the washing phase, wherein the machine is arranged to operate such that after said washing phase and before said rinsing phase said impeller for circulating the hot air is activated for a predetermined period of time.

2. A machine according to claim 1 wherein activation of said impeller is automatically determined by suitable control means disposed within said machine.

3. A machine according to claim 1 or claim 2 wherein before said phase of operation of the impeller is activated the tub is emptied.

4. A machine according to any one of the preceding claims wherein said impeller is activated after each phase of emptying the tub.

5. A machine according to any one of the preceding claims and comprising a conduit for communicating the chamber of the impeller with means for distribution of the water, which can be freely vented to the exterior.

6. A machine constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.