Improved closing system in plastic tank for washing machine

Abstract: Improved closing system in plastic tank for washing machine, being of the kind of the plastic tanks that are made up of two halves that are obtained from a mould, staying open the union base in both halves, while the other base of one of the halves coincides with the frontal part of the tank that is relative to the washing machine door and the other one defines the closed back part with the central axial hole for the pass of the drum spindle, so that the two halves (1) and (2) define the washing machine tank by means of their union and they have a plurality of radial lungs that are backed among them. Thus, the lungs of one of the halves have the respective projections while the backed lungs have the respective passing holes, so that the projections, that are like a right angle to the radial lungs (3) of one of the tank halves (1), are defined by the respective studs (7) which are endowed of an axial central hole.

Description: SUBJECT MATTER OF INVENTION The invention relates to an improved closure system for a washing-machine plastic tub of the type made out of two moulded halves, the face to be joined remaining open for both halves while for one of the halves the other face corresponds to the front of the tub in relation to the washing-machine door, and for the other half, the other face forms the closed rear side with a central, axial opening allowing the drum spindle to pass, so that the two halves can be separated in the event of any malfunction by servicing personnel, to allow access to its interior for repairing such malfunction. By means of the closure system disclosed in this description, joining the two halves of the tub is facilitated by this very easy and fast operation, lowering the costs for the material used in the joining and providing substantial economic savings. Moreover, the closure system permits, if necessary, servicing personnel to separate the two halves easily and rapidly so that, once the malfunction has been repaired, the two halves of the tub can be reassembled conventionally by means of screws and corresponding nuts. Of course plastic tubs consisting of two shells are known from EP 0 103 418 A1, EP 0 152 745 and from EP 0 497 109 A1. In EP 0 103 418 A1 the shells can not be separated afterware since they are welded together and the shells of EP 0 497 109 A1 and EP 0 152 745 are assembled by screw fastening. Thus, the aim is to obtain a completely reliable closure of the two halves of the plastic tub as well as to allow their separation by servicing personnel and their subsequent reassembly. Starting from these engineering requirements, this description discloses two practical uses of the invention, both of which are characterized by fast and economic implementation and assembly while, if need, the two halves of the tub can be disassembled and reassembled for normal functioning. The petitioner hereunder is likewise holder of patent no. ES P 96 00 222 (EP 0 789 104), which discloses a closure system for a washing-machine plastic tub pursuing the same objectives of being able to provide a rapid and economic closure system, which can be both disassembled and reassembled. FIELD OF APPLICATION The closure system disclosed in the description set forth below applies to the joining of two halves of a washing-machine plastic tub, both of which halves are made by moulding. For the manufacture of these halves there is no need to make the mould more complicated since the elements constituting the joint, likewise obtained by moulding, do not render either the mould or the product as such more expensive. Thus, the two halves of the tub determine its configuration upon their joining along their central periphery subsequent to introducing the corresponding seal for watertightness, while one of the faces of one of said halves has an opening with respect to the door of the washing machine and a face of the other half forms the closed rear member and has a central, axial opening to allow for the drum spindle to pass. BACKGROUND OF THE INVENTION Plastic tubs of washing machines are conventionally moulded as two halves which, once joined, form the tub of the washing machine that houses the drum so that the body of the tub itself is made in a way to form the attachments required to fasten it and to join it to other items as well as to be able to join the two halves with each other in order to form a watertight housing. Thus, the two halves forming the tub of the washing machine are joined peripherally along their central outline in a way to leave one of the halves open with respect to the front door of the washing machine while the other half forms the rear part of the tub and has a central, axial opening allowing the drum spindle to pass through and be held by the tub. In order to realize the joining of the two halves of the tub around their open faces, some radial lugs are formed and provided with openings to allow for tightening the corresponding screws used to materialise the closure. At the same time, the corresponding annular seal is placed between the two members to be joined to guarantee a water-tight closure. Thus, the joining of the two halves is done by a number of screws fastening the two members together so that one or several operators have to tighten the screws, which takes much time assuming that joining the two halves will require approximately 17 screws. With this configuration we have to consider that assembling the tub will make it necessary to use the number of screws indicated, entailing the relevant costs as well requiring much time used to tighten them all, resulting finally in high costs due to value added by the screws used and the work required to carry out the closing operation. Thus, the washing-machine tub so configured can be disassembled if necessary for technical purposes by separating the two halves upon removing all fastening screws while, later on, it can be reassembled once the two halves forming the tub have been attached to each other again by means of said fastening screws. Moreover, as has already been stated, the applicant hereunder is the holder of patent no. ES P 96 00 222 which discloses a closure system for the plastic tub of a washing machine which basically consists in providing one of the halves of the tub with a multiplicity of projections having the shape of a harpoon tip that, during assembly of the two halves, are placed against corresponding recesses on the other half of the tub, junction being achieved by lodging the projections having the form of a harpoon tip in said recesses. This embodiment allows the two halves to be separated if required by breaking the fastening elements so that both halves can be rejoined again by means of the corresponding lugs having openings for positioning the relevant fastening screws. DESCRIPTION OF THE INVENTION In this description, an improved closure system for the plastic tub of a washing machine is described, which tub is of the type made out of two halves obtained by moulding, the faces to be joined of such halves remaining open while in one of the halves the other face corresponds to the front of the tub relative to the washing-machine door, and for the other half, the other face forms the closed rear part having a central, axial opening to allow the spindle of the drum to pass so that the two halves, when joined, form the tub of the washing machine and have a multiplicity of radial lugs abutting on each other. Thus, the right-angle projections attached to the outside face of the radial lugs of one of the tub halves are formed by corresponding studs having a central, axial hole made relative to the point of its origin on the corresponding lug. The studs moulded solid with the lugs on one half of the tub have a central, axial blind hole so that when held within, and protruding from, the openings of the lugs attached to the other half, heat is applied to the free protruding ends of the studs which will melt and form a thickening in the form of a spherical cap having a diameter superior to the opening of the lug in which the stud is held so that, upon solidifying and cooling, they are fastened on to each other. Moreover, the studs moulded solid with the lugs of one half of the tub can be provided with a central, axial through hole so that when held within, and protruding from, the openings of the lugs attached to the other half as heat is applied onto any protruding end it will melt and form a thickening having the form of a peripheral ring of semicircular cross-section with a diameter superior to the opening of the lug holding it so that, upon solidifying and cooling, a fastening as by rivets is materialised. So as to ensure that, during the joining process by melting the free ends of the studs the two halves of the tub will remain perfectly aligned while the melted material solidifies and cools, both halves are placed under constant pressure preventing the pressure generated by the annular joint from displacing the two halves relative to each other. In a second practical embodiment of the invention, the right-angle projections on the radial lugs around one of the tub halves are formed by a tubular member each while the lugs on the other half of the tub have an opening with a chamfered border on the side opposite the abutting face and with respect to which there is, moreover a pair of reinforcements supporting a truncated cone, all of it made during the same moulding process as used for the above-mentioned tub half. The tubular member are provided at their free ends with a pair of radial slots diametrically opposed to each other, while through hole is located centrally. The joining of the halves forming the tub is realized, once the tubular members moulded solid with the corresponding lugs on the other half of the tub have been inserted, and by pressing the truncated cones supported by the pair of reinforcements into the tubular members aligned with them, the ends of said tubular members opening along the chamfered border of the opening where they lodge. To complement the following description and in order to facilitate the understanding of its characteristics, a set of drawings is added to this description. The figures show, only by way of illustration and not of limitation, the most significant details of the invention described herein. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a detailed perspective view of a junction point of the two halves of a washing-machine plastic tub displaying a stud moulded solid with one of the lugs and provided with an opening related to its point of origin and a hexagonal recess. The lug on the opposite half of the tub is provided with a seating orifice for the stud. Fig. 2 shows a radial section view of a junction point between the two tub halves where the stud is seated in, and passing through, the opening of the abutting lug on the other half of the tub, the stud having a central, axial blind hole. Fig. 3 shows a radial section view of a junction point of the two tub halves relating to the preceding figure upon application of heat to the free end of the stud to provoke its melting and the anchoring of both halves by creating a thickening shaped like a spherical cap having a diameter superior to the opening, which constitutes the junction once the material has solidified and cooled. Fig. 4 shows a radial section view of a junction point between the two halves of the tub where the stud is held by, and passing through, the opening of the abutting lug, on the other half of the tub, the stud having a central, axial through hole. Fig. 5 shows a radial section view of a junction point of the two halves of the tub corresponding to the preceding figure subsequent to applying heat to the free end of the -stud in order to provoke its melting and the anchoring of the two halves upon forming a thickening in the shape of a peripheral ring, similar to a rivet, having a semicircular section with a diameter superior to the opening, which constitutes the junction once the material has solidified and cooled. Fig. 6 shows a detailed perspective view of another practical embodiment of the invention in which a radial lug on one of the tub halves has a right-angle projection in which, at its free end, a pair of diametrically opposed radial slots have been made, while the abutting lug on the other half of the tub has an opening which, on the side opposite to the abutting face has a chamfered border, and in respect to said face a truncated cone moulded solid with a pair of reinforcements made during the injection moulding of the tub body itself. Fig. 7 shows a radial section view of a junction point of the two tub halves, relating to the previous figure, in which the tubular member on one lug of the tub halves is held within, and passing through, the opening of the abutting lug on the other tub half, said truncated cone being arranged so that one press stroke will insert it under pressure into the tubular member, thus materialising the junction between the two halves of the tub. DESCRIPTION OF A PREFERRED EMBODIMENT In view of the figures commented upon, and in compliance with the numbering adopted, it is to be seen that the two halves 1 and 2 made by moulding and forming, upon being joined, the plastic tub of the washing machine, have a multiplicity of lugs 3 and 4 respectively arranged around the periphery of the open, abutting face so that lugs 3 on one half of the tub have at their outer faces appropriate projections, while lugs 4 on the other corresponding half of the tub have through holes to lodge the projections mentioned. Otherwise, the closed face of one of the halves forming the tub constitutes said closed face having a central, axial opening allowing the spindle of the drum to pass, while the other face on the opposite half contains an opening arranged relating to the door of the washing machine. Moreover, as regards, the periphery of the faces of the two halves 1 and 2 to be joined to form the tub of the washing machine, one of them has a recess 5 in which a corresponding annular seal is lodged on which lip 6 on the opposite half to be joined will rest. Conventionally the two halves of the tub to be joined have a multiplicity of lugs provided with corresponding through holes which, during the assembly of the two halves, are abutted against each other so as to form the junction by means of screws and corresponding nuts, said junction being implemented by means of approximately 17 screws, which increase expenses both by the cost of the screws themselves and by the time required to screw them down. So as to provide a solution for this drawback, patent no. ES P 96 00 222 already discloses a junction system for two halves of a tub by means of a number of projections having the shape of a harpoon tip that are inserted and retained in corresponding recesses so that a junction is achieved by a simple press stroke. This form of anchoring makes it necessary to rupture, whenever the tub is disassembled, said anchoring means so as to free the two halves. Subsequently, they have to be reunited by conventional means, upon joining the two halves of the tub, via the corresponding lugs having appropriate through holes to allow for placing the fastening screws. The present invention discloses an anchoring system constituted by two practical embodiments that both can be disassembled to allow for servicing the tub in the case of malfunction. Both embodiments are very simple and thus very economic. In one practical embodiment of the invention, the lugs 3 on one of the halves 1 constituting the tub have, relative to their internal faces various studs 7 with a central, axial hole while on their opposite face, said lugs 3 have a hexagonal recess 9 and the other half 2 of the tub bears corresponding lugs 4 having appropriate openings 8. Thus, in joining the two halves 1 and 2 constituting the tub, studs 7 having a central, axial blind hole 10 with respect to their point of origin are passed through the relative openings 8 so as to protrude from the holding lugs. While maintaining constant pressure on both halves, heat can be applied to the free ends of the protruding studs so that they will melt and form a spherical cap with a diameter superior to the opening which, subsequent cooling will produce a perfect closure between both halves. Moreover, studs 7 can be provided with a central, axial through hole so that, whenever heat is applied to them, their ends will melt and form a peripheral ring 13 having a semicircular section like a rivet, which likewise results in a perfect closure between the two halves subsequent to cooling. The pressure exerted upon the two halves of the tub while the free ends of said studs 7 are being melt will be maintained until the melt material has solidified and cooled in order to produce a perfect closure between the two halves. In fact, a perfect junction is obtained by spot welding the two halves of the tub together, which is a quick and economic process having the advantage that, if the tub has to be serviced, the two halves 1 and 2 can be separated easily by a drill to rebore the spot welds to free them. This operation is preferably done through the holes in studs 7 that will guide the drill bit and leave all holes in lugs 3 and 4 entirely clean, already having the diameter required for screwing the tub together later on. In a second practical embodiment of the invention, lugs 3 on half 1 of the two halves constituting the tub show on their external faces various tubular members 14 provided at their free ends with a pair of radial slots 15 so that said tubular members 14 are held in the corresponding openings 16 of lugs 4 on the opposite half of the tub but projecting beyond it. During the moulding of half 2 of the tub, opening 16 has a chamfered border 17 formed on its inside as well as reinforcements 18 supporting a truncated-cone member 19 in alignment with opening 16 of the corresponding lug 4. Based on this configuration, the truncated-cone members 19 will be pressued in said tubular members 14 held within the corresponding openings 16 and projecting beyond them in a manner so that the two limbs formed on their tips by slots 15 adapt to the chamfered border 17 of opening 16. Even though the described junction will be perfectly anchored, the tubular member 14 may be provided, in order to secure members 19, on its inside with counter-projections 20 ensuring the positioning of said truncated-cone member 19. Once the two halves 1 and 2 of the tub are joined they can be released again, as in the case described above, by using a drill on the points of junction, for which lugs 3 have axially central holes in the tubular member 14, making it possible to guide the drill bit while, on their inside faces, they have a hexagonal recess to seat the head of the corresponding fastening screw used subsequently to join both halves. In conclusion, a rapid and secure joining is obtained that makes it possible for servicing personnel to disassemble it whenever this might be necessary and allows reassembly of the two halves by means of conventional screws and corresponding nuts positioned relative to the appropriate holes in lugs 3 and 4.

Claims: Improved closure system for a washing-machine plastic tub of the type made out of two moulded halves (1, 2), the face to be joined remaining open for both halves while for one of the halves the other face corresponds to the front of the tub in relation to the washing-machine door, and for the other half, the other face forms the closed rear side with a central, axial opening allowing the drum spindle to pass, characterised in that the two halves (1, 2) which, upon joining, constitute the tub of the washing machine, have a multiplicity of radial lugs (3, 4) near the joining face abutting against each other, all the lugs (3) on one (1) of the halves disposing of projections in the form of right-angle studs (7) while the lugs (4) on the other half (2) abutting them having corresponding openings (8). Closure system according to claim 1, characterised in that the right-angle studs (7) are provided with an axial, central hole (10,12). Closure system according to one of the preceding claims, characterised in that the studs (7) moulded solid with the lugs (3) on one (1) of the halves of the tub have a central, axial blind hole (10), said studs are held within, and protrude from the openings (8) and on the free ends said studs have been heated in order to form a thickening in the shape of a spherical cap (11) with a diameter superior to the one of openings (8), so that, upon solidification and cooling, they materialise the junction. Closure system according to claims 1 or 2, characterised in that the studs (7) moulded solid with lugs (3) on one (1) of the halves of the tub have a central, axial through hole (12), said studs are held within, and protrude from, the openings (8), and on the free ends said studs have been heated in order to form a thickening in the shape of a peripheral ring (13) of semi-circular cross-section with a diameter superior to the one of openings (8) so that, upon solidification and cooling, they materialise the junction. Closure system according to claims 3 or 4, characterised in that during the heating process of the free ends of the studs (7) and upon solidification and cooling of said thickenings (11,13), constant pressure is applied to both halves, allowing for perfect junction and forming of the tub. Closure system according to claim 1, characterised in that the right-angle studs (7) on the radial lugs (3) on one (1) of the halves of the tub are formed by tubular members (14) while the lugs (4) on the other half (2) of the tub have an opening (16) with a chamfered border (17) on the side opposite the abutting face to which there is likewise moulded integrally a pair of supports (18) holding an outside truncated-cone member (19). Closure system according to claim 6, characterised in that the tubular members (14) are provided on their free ends with a pair of radial slots (15) while a through hole constitutes their central part. Closure system according to claim 7, characterised in that the junction of the two halves (1, 2) is materialised, once tubular members (14) have been inserted into the relevant openings (16) and the outside truncated-cone members (19) have been pressued into the tubular members (14), their free ends spreading along the chamfered border of opening (16), in which they lodge.

Inventors: BOVED ISMAEL GRACIA, BOVED, ISMAEL GRACIA
Applicants: BSH BALAY SA, BSH BALAY, S.A.
Application year: 1998
Main classification: D06F37
IPC codes: D06F37