GB2294952A - Washing machine structure - Google Patents

Abstract

A clothes washing machine has a washing tub 1, a drum which rotates within said tub and which is capable of containing the articles to be washed, a motor 2 for rotating the drum at different speeds, a counterweight 8, 9 fixed to said tub, said motor being fixed exclusively to said counterweight. Preferably said counterweight is formed by an external shell of plastics material filled internally by high-density material, and is preferably produced in one piece with the tub. Alternatively the counterweight is composed at least partially of material originating from recycled solid urban wastes (SUW). <IMAGE>

Description

WASHING NACHINE WITH IMPROVED STRUCTURE The present invention concerns the construction of machines for washing laundry, which is provided with economical and silent structural elements and the constituent material of which is particularly suited to being recycled and reused after dismantling of the machine on which they are originally installed.

As is known washing machines normally comprise, in the interior of a casing, a series of operative members which undesirably generate noise. Clothes washing machines in particular have a washing unit which is associated with at least one motor-driven discharge pump is suspended resiliently in the interior of the casing and comprise a drum for the laundry, which is adapted to be driven in rotation by means of an electric motor. In addition, for the purposes of limiting unbalance phenomena of the washing unit during rotation of the drum, the washing unit is provided with suitable ballasting means which are generally formed by a mass of cast iron and/or concrete.

Conventionally the housing also accommodates a series of further operative members such as a motor-driven discharge pump, electrically operated valves etc, all of which undesirably generate noise during operation of the machine. In particular it is known that the drive motor generally produces noise involving components at relatively low frequency (of the order of around 200-300 Hz) which are particularly disturbing in a domestic environment and which are difficult to eliminate with the conventional sound insulating systems, in particular since the motor is normally mounted to the washing tub and therefore the vibrations generated in the motor are transmitted directly to the tub which acts as a sound box and thus tends to amplify the noise produced by the vibration.

There is however the known requirement for limiting the noise produced by such machines, in particular the noise produced by the motor for actuating the drum or the circulation pump, which is particularly disturbing in the frequent situation in which the machine is used during the night.

To remedy that disadvantage, some designs have been produced which incorporate various devices for reducing the emission of noise, such as for example silenced motors, tubs of plastics material etc.

Even if those constructions have turned out to be sufficiently effective, they do however require a radical redesign of the clothes washing machine, and that is often not possible for economic or industrial reasons.

To reduce noise therefore attempts have been made to improve the hydraulic circuits, the electrical components and the mechanical members of the washing machines, but with unsatisfactory results. In addition the use of special sound-absorbent or sound-insulating panels undesirably complicates the structure and manufacture of the machine which generally does not involve in the interior thereof sufficient space for suitably accommodating such additional components.

In any one case, it has been found by experience that such constructions are capable of reducing the noise components at a relatively high frequency, but they are substantially ineffective in dealing with the noise components at a relatively low frequency, which are those which are more disturbing in a domestic environment.

Clothes washing machines are also known which are produced in conventional fashion by cladding the internal functional parts with an external metal casing; that design configuration is universally adopted for producing casings for such simple and economic clothes washing machines which are normally formed by a sheet or plate facing which encloses the machines at the sides and in front, and a rear panel member which is produced separately and which can also be fitted or removed separately to permit access from the back to the main functional members.

However, even if that type of construction is sound and economical, it does not permit a significant reduction in the noise which is generated from the interior of the machine and which is thus freely propagated to the exterior, since the metal walls also often constitute a sound box in relation to said noises.

It would thus be desirable, and this is the aim of the present invention, to be able to provide a clothes washing machine capable of substantially reducing the amount of noise originating from the tub and the casing and induced by the vibrations transmitted from the motor, in a very simple and reliable fashion, with the insertion of inexpensive components and using current technologies.

According to the present invention, there is provided a clothes washing machine provided with a washing tub, a drum which rotates within said tub and which is capable of containing the articles to be washed, a motor for rotating said drum at different speeds, and a plurality of counterweights which are connected to said tub, wherein said motor is fixed exclusively to at least one of said counterweights.

The invention will be better appreciated from the following description given solely by way of non-limiting example an d with reference to the accompanying drawings in which: - Figure 1 is a diagrammatic view of the various components involved with the invention in a clothes washing machine; and Figure 2 is a simplified perspective view of a washing unit of a clothes washing machine according to the invention.

Referring to Figure 1 which shows a preferred embodiment, illustrated therein is a solution according to the invention and the operating principle thereof.

The clothes washing machine described has a washing tub 1, a drum which rotates within the washing tub and which is capable of containing thee articles to be washed, a motor 2 which is normally an electric motor and which is connected to said drum and which is capable of rotating it at variable speeds by means of two pulleys 3 and 4 which are respectively fixed to the shafts of the motor and the drum, and a belt 5 which connects the pulleys.

Even if they are not shown, all the other elements which are known in the state of the art and which contribute to governing the conditions for correct operation of the machine are also to be deemed present.

The machine also has one or more external counterweights 8,9 fitted to the tub by per se known means.

The invention is based on the adoption of two particular innovative solutions relating to different techniques of use and mounting of the materials in a clothes washing machine: - The first solution concerns the method of mounting the motor for driving the drum; as already stated, in accordance with a universally adopted technology, the motor is mounted directly to the tub to achieve some structural advantages which are known to the man skilled in the art. In accordance with the present invention on the other hand the motor is applied and fixed exclusively to one of the counterweights 8 which is rigidly fitted to the tub.

This first solution achieves an initial result of separating the motor from the tub, whereby the vibrations of the motor have to be transmitted by way of the counterweight to reach the tub.

That solution, although useful, however would be of somewhat limited effectiveness from the point of view of noise transmission if the arrangement uses absolutely rigid ballast members which are composed of materials which strongly conduct vibration and noise such as metal, in particular cast iron, or concrete, which are often used for that purpose.

If however it were possible to use materials with characteristics of improved insulation with respect to vibration while however being substantially rigid and easy to work, the desired aim would then be achieved.

It therefore is considered that such a material may be a thermoplastic-base material, provided that it is sufficiently robust, of high density and with good vibrationattenuating characteristics. The fact then that thermoplastic material is used ensures excellent workability.

Numerous plastic materials which as a general rule could serve for the purpose can be easily identified; however such materials suffer from disadvantages which make the described use thereof less advantageous; for example if the arrangement uses counterweights which are completely of virgin plastics material, they suffer from costs which are markedly higher than the conventional counterweights; if the arrangement uses plastics materials which are sufficiently yielding or soft to attenuate the vibrations, they are normally also of low density so that to produce counterweights of the desired weight, it would be necessary to increase the volume thereof, but that encounters the limitation of available space; if finally consideration were given to producing counterweights of differentiated densities, such as for example counterweights with a rigid but heavy core which are completed by a light but soundinsulating surface covering, that would have major repercussions on the associated costs.

- The second solution therefore concerns producing counterweights substantially of plastics material but without suffering from the above-mentioned disadvantages.

That is based on the alternative of using counterweights whose external zone is composed of thermoplastic material while the interior is of high-density material, said counterweights being produced in one piece with the tub which is obviously made of thermoplastic material, and the use of counterweights of in particular recycled thermoplastic material of high density and involving low cost, to be used on any type of tub as conventional counterweights.

In relation to the first alternative it is known for example from Italian Utility Model Patent (application) No PN92 U 000009 to produce counterweights formed by an external shell of thermoplastic material and an internal mass of high-density sound-absorbent material, especially barium sulphate: The invention involves producing a tub of plastics material in one piece with said external shell of the counterweight, using one of the many embodiments known in the state of the art, filling the cavity delimited by said external shell with a high-density sound-absorbent material of the type described.

The motor is then fitted to the zone of the external shell of the counterweight, by virtue of the flexibility in terms of processing of the thermoplastic material which makes it possible to provide means for coupling and fixing the motor.

That first alternative therefore economically permits the motor to be fitted to a counterweight which is produced in an economical fashion and affords elevated characteristics in respect of insulation relative to the vibration transmitted from the motor.

The above-mentioned second alternative is based on the use of counterweights which are obtained by the use of suitably selected and pre-treated materials deriving from the collection of solid urban wastes (SUW) which are recompacted by means of compressing prior to extrusion with possible additions of binding elements, or mixtures and compounds of various origins, in particular deriving from waste from industrial processing operations or chemical processes, having physio-chemical and mechanical characteristics similar to those of the SUW.

Procedures are indeed known for the extrusion at low temperature of thermoplastic materials of various natures and characteristics, in particular materials which melt at low temperature, together with materials which, melting at high temperatures, are simply incorporated without being melted and thus without producing toxic or noxious derivatives; such procedures are capable of permitting recycling and re-use of SUW which have been previously filtered and treated and which possibly have binding substances added thereto, with prevailing plastics components which are also incompatible and with widely varying melting characteristics for the production of articles of thermoplastic-based material involving limited technical requirements, without having to involve and bear the disadvantages and limitations of expensive differentiated collection; in addition the wide range of low-cost mixtures which can be used make it possible to produce articles of high specific weight, without substantially limiting the sound-insulating capacity. The use of such procedures of reproduction of the counterweights which are made from materials which are derived at least partly from the SUW affords an opportunity to solve in a different fashion the problem of economic, compact and sound-insulating counterweights; indeed the counterweights produced in that way are of very low cost which is certainly below that of the counterweights produced using virgin material, while the feared limitations in respect of use, that is to say the limited technical characteristics, are not at all a limit in regard to use of the counterweights which are used precisely like ballast.

In addition, the present invention makes it possible to produce counterweights which can be easily worked and moulded, which makes it possible to design types of counterweights which are provided with means to which it is possible easily to fit other components of the machine by means of completely automatic working operations, which is not permitted with counterweights of concrete.

In addition the elimination of concrete from the new counterweights makes it possible to over the disadvantages linked thereto, such as crumbling, fracturing, electrical defectiveness and mechanical jams due to the concrete powder which infiltrates into the associated mechanisms.

It will be apparent that the man skilled in the art can identify other technical solutions and optimisations in terms of use of the present teaching by having recourse to the normal procedures and knowledge of the art; although therefore the invention has been described using generally known technology, it is not considered limited by the examples given.

Claims (6)

1. A clothes washing machine provided with a washing tub, a drum which rotates within said tub and which is capable of containing the articles to be washed, a motor for rotating said drum at different speeds, and a plurality of counterweights which are connected to said tub, wherein said motor is fixed exclusively to at least one of said counterweights.

2. A machine according to claim 1 wherein said counterweight is formed by a homogeneous mass of thermoplastic-base material.

3. A machine according to claim 1 wherein said counterweight is formed by an external shell of plastics material and an internal mass of high-density sound-absorbent material, preferably barium sulphate.

4. A machine according to claim 3 wherein said tub is of plastics material and is formed in one piece with said external shell of said counterweight.

5. A machine according to claim 1 wherein said counterweight is composed at least in part of material originating from recycled SUW which is recompacted by means of extrusion at low temperature, preferably with the addition of binding substances.

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