Ballasted tub for washing machines

Abstract: Ballasted tub for washing machines, particularly clothes washing machines or combined clothes washing and drying machines, comprising two circular shells (9, 10) of plastic material which are adapted to be fitted and connected with each other along their periphery and are shaped in such a way as to be adapted to accomodate a plurality of ballast blocks (8) made of concrete or other suitable heavy material. Said ballast blocks (8) are pre-formed and applied against the corresponding front and rear surfaces of the shells (9, 10) by means of removable fixing means (22,23,24,25,27,31,32) of a per sè known type, thereby implementing a ballasted tub with a modular structure, wherein both the disposition and the combination of the ballast blocks (8) can be varied at will in view of the ability of balancing differently shaped and sized tubs therewith.

Description: The invention relates to a ballasted tub for washing machines, in particular clothes washing machines or combined clothes washing and drying machines, said tub being designed in a structurally rigid way and being provided with a quick and simple system for fastening the various ballast masses in position. Washing machines provided with ballast masses applied to the wash tub in different manners are known from the prior art. According to one of these prior-art embodiments, the ballast is formed by a previously prepared concrete block or masses of heavy material of any suitable kind, which are fixed on to the front wall of the tub of the respective washing machine by means of removable fastening means such as screws, bolts, nuts, washers and the like. FR-A-2 359 924 discloses a ballasted tub for washing machines, onto the front wall of which ballast masses of heavy material are applied by means of a locking ring, a water-tight seal and fastening means. Said technical solution does not allow the machine to operate at high spinning speeds, due to possible loosening of this assembling. In all these cases, however, the presence of several fastening means of various kind makes such a ballast provision complicated in its design and construction and leads to difficulties and unconveniences in assembling the tub. Furthermore, according to a further prior-art embodiment, the ballast comprises a moulded plastic flange forming the front wall of the tub and being in the shape of a continuous grooved ring having a U-shaped cross-section profile, which is adapted to accomodate a concrete mass, said flange being further provided with a plurality of radial ribs formed on in correspondence of the open front surface of the same flange, so as to retain in its seat the concrete mass that is poured into the cavities resulting between said continuous ring and the respective radial ribs. The flange with the thereby applied concrete ballast is subsequently applied against the curved edge of the cylindrical mantle of the tub by means of a clamping ring which is fitted into the corresponding perimetral groove of said flange upon interposing a sealing gasket therebetween. In practice, this type of tub design has the drawback of being constructively complicated, owing to the need of first manufacturing the plastic flange and then casting the concrete in the cavities of the same flange, which fact further prevents the ballast from being possibly given a modular design so as to generate the possibility of adapting the same ballast to balancing applications in connection with differently shaped and sized washing machine tubs, which can be installed in different types of washing machines. Furthermore, such concrete masses can undesirably become loose and come off their seats in said moulded plastic flange, so that these masses will fall outside the flange itself, owing to the effect of both the vibrations generated during the operation of the washing machine and the shrinkage of the concrete inside said seats. It is therefore the purpose of the present invention to eliminate all of the afore cited drawbacks by providing a washing machine with a ballasted tub that is made in such a way so as to ensure an effective, reliable support to the concrete ballast mass, which can also be made to a modular design concept for adaptation to differently shaped and sized tubs, as well as to ensure a quick and simple assembly of said ballast on to the front wall of the tub. Such a ballasted tub is embodied with the design and construction characteristics as essentially described and defined with particular reference to the appended claims. The invention will be further decribed by way of non-limiting example with reference to the accompanying drawings in which: Figure 1 is a perspective view of the front portion of a ballasted washing machine tub according to the invention; Figure 2 is a perspective view of the rear portion of the ballasted washing machine tub as in Figure 1; Figure 3 is the view of a construction detail of the rear side of the ballasted washing machine tub as in Figure 2; Figures 4 and 5 are the views of two further construction details of the ballasted washing machine tub according to the invention; Figure 6 is a side cross-sectional view of a portion of the ballasted washing machine tub as in Figure 1. Referring now to the Figures 1 and 2, both of them show the ballasted washing machine tub 7 according to the invention, which is adapted to hold and support ballast masses 8 against its front and rear walls in the hereinafter described way, and which is also adapted to be mounted inside the cabinet (not shown) of a clothes washing machine or a combined clothes washing and drying machine. Furthermore, as it appears from the above cited Figures 1 and 2, the tub 7 is made of plastic material and is formed by two shells 9 and 10 which are mutually adaptable and connectable along their respective circumferential surfaces, where the seats for both the upper suspension springs 11 of the tub-and-drum assembly and the lower shock absorbers (not shown) are also provided, by means of per sè known fastening means such as threaded bolts 12, screws and the like. The ballast masses 8 are in turn formed by a plurality of pre-formed blocks of heavy material, such as concrete or the like, which are preferably made in the form of sectors of a circle having similar thickness and height, and so shaped as to be capable of being fitted and fixed in a mutually adjoining, side-by-side arrangement against the respective, mutually opposing front and rear walls 9 and 10 of the tub 7. In particular, in this example of an embodiment of the tub according to the invention, the front-side ballast appears as being formed by three pre-formed blocks 11, 12 and 13, ie. an upper block 11 in the shape of a sector of a circle and two lower blocks 12 and 13 that are symmetrical to each other and are provided with a portion in the shape of a sector of a circle 14, 15 and an enlarged portion of a downwards tapered shape 16, 17, respectively. The rear-side ballast appears in turn as being formed by a single upper block 18 (see Fig. 2) in the shape of a sector of a circle. Furthermore, as it quite clearly emerges in particular from Figure 4, where a ballast block in the shape of a sector of a circle is illustrated, each block of this kind is provided with two grooves 19 and 20 running along the full height of said block in a transverse direction with respect to the same block, so as to enable it to be fastened in position in the hereinafter described way. Referring now to the Figures 1, 5 and 6, it can be seen how these illustrate the way in which the blocks forming the front-side ballast are applied and fixed in position. From the above cited Figures it can be seen that, to this purpose, the front shell 9 of the tub 7 is provided with three portions protruding frontally from said tub (only the portion 21 is shown in Figure 1) in correspondence of the terminal zones of each ballast block, each one of said protruding portions being capable of accomodating two square-shaped metal plates 22 and 23, through the threaded hole of which a respective bolt 24, 25 can be inserted for fixing the various ballast blocks. Each ballast block is furthermore sized so as to perfectly adapt and fit against the front wall 9 of the tub 7 in a position lying underneath the respective protruding portion of the same tub, and presents its transversally running grooves 19 and 20 in such a position that, when said block is applied in its seat, they fall in a line with the respective bolt 24, 25 so as to enable it to pass through. In practice, each one of the above described fixing bolts is inserted through its respective square plate and transverse groove, as well as through a corresponding slot-shaped hole 26 provided in a circular metal band 27 (see Figs. 5 and 6), which is applied all around the front opening 28 of the tub 7, against the outer surface of the respective ballast block, said metal band being provided at its ends with respective slots 29 and 30 coinciding with each other so as to enable said band ends to be mutually connected by means of per sè known fastening means (not shown), in such a way that said metal band will be capable of being adapted on to ballast blocks having differing diameters. The free threaded end of each bolt is then inserted through a washer 31 or similar means, and on the same washer or similar means is finally screwed a corresponding lock nut 32, thereby causing each single ballast block to be firmly applied and fastened in position, without any possibility of becoming later displaced with respect to the other ballast blocks fixed in the same way. The block forming the rear ballast is in turn housed in a seat which is obtained between an upper circular portion 33 and a lower circular portion 34, both protruding from the rear wall of the tub 7, while said ballast block is then secured to the tub assembly by having resort, as in the preceding case, to square metal plates arranged on said upper and lower portions, as well as to the described bolt and lock-nut system, wherein each bolt is inserted through a respective transversal groove in the same block. By looking now at the Figure 3, it can be finally seen that the above cited ballasted tub is further provided on the outer surface of its rear wall 10 with a plurality of radial ribs 35, which are identical and distributed regularly along a circular direction, as well as at least one circular rib 36 having a greater radius than the hub 37 (ensuring the passage of the drum driving shaft, not shown), said circular rib blending into said radial ribs so as to give the tub a rigid structure with a high mechanical strength to adequately withstand the stresses imposed by the drum rotating at its regular wash and spin-extraction speeds. The ballasted tub provided in this way according to the invention ensures an effective and reliable supporting means for the various ballast masses and, owing to the modular concept according to which said masses are designed, it is possible to vary their arrangement and set-up according to the particular type of tubs being handled, so as to be able to balance differently sized and shaped, separately manufactured wash tubs by just using different combinations of the same ballast masses.

Claims: Ballasted tub for washing machines, comprising two shells made of plastic material which are reciprocally adaptable and connectable, and onto the respective front and rear wall of which ballast masses of concrete or similar heavy materials can be applied by means of fastening means, characterized in that each ballast mass (8) comprises at least two grooves (19,20) extending transversally over the full height thereof, fastening means (22,23,24,25,27,31,32) being associated to said grooves in order to fasten said ballast masses on said tub. Ballasted tub according to claim 1, characterized in that said fastening means comprise at least a metal plate (22, 23), a threaded bolt (24, 25), a metal band (27) adaptable against said ballast masses (8), a washer (31) or the like and a lock nut (32), said threaded bolt (24, 25) being insertable through corresponding holes in said metal plate (22, 23) and in said metal band (27) as well as through a corresponding transversal groove (19, 20). Ballasted tub according to claim 1, characterized in that it comprises on its rear wall (10) a plurality of radial ribs (35), which are identical to each other and regularly distributed in a circle, and at least a circular rib (36) blending into said radial ribs (35) so as to stiffen the structure of the tub and increase its ability to withstand shocks, vibrations and mechanical stresses.

Inventors: VALENT LUCIO, VALENT, LUCIO
Applicants: ZANUSSI ELETTRODOMESTICI, ZANUSSI ELETTRODOMESTICI S.P.A.
Application year: 1992
Main classification: D06F37
IPC codes: D06F37