COMPOSITE STRUCTURE TUB FOR A WASHING MACHINE OF THE RADIAL-LOADING TYPE

Abstract: A tub for a washing machine comprises a circumferen­ tial metal wall (1) formed with a loading opening (13) and sealingly cooperating with opposite disc-shaped end walls (2,3) made of a plastic material. The end walls incorporate respective support bearings (4,5) for a drum (7) mounted for rotation about a horizontal axis (6). One end wall (3) is preferably circumferentially welted to the rim of the circumferential wall (1).

Description: Composite Structure Tub for a Washing Machine of the Radial-Loading Type Description The present invention relates to a tub for a laundry washing machine with a drum mounted for rotation about a horizontal axis and adpted to be loaded from above, that is, through the circumferential walls of the drum and the tub. Already known are tubs for washing machines of a composite structure consisting of metal and plastic components to thereby combine the advantages of the mechanical strength of the metal components with the advantages of the sealing capability and resistance to corrosion typical for plastic components. In practice, however, tubs of this type are usually of an undesirably complicated construction. A composite tub having a relatively simple structure is described for instance nr. 5-PS i,#55,7'46. Basically this tub is formed of a circumferential wall of a plastic material sealingly cooperating with two disc-shaped end walls made of metal. The various components are secured to one another by means of tension bolts extending between the two end walls. This solution also presents a number of shortcomings. In the conventional manner, the heater elements for heating the washing liquid are disposed in proximity to the circumferential wall of the tub, that is, close to a plastic component which should be protected against overheating. This entails the necessity of providing the machine with suitable electric circuits or similar safety components for ensuring adequate protection of the tub against overheating. As a result, the overall construction of the machine becomes undesirably complicated. Moreover, the reliable assembly of the circumferential wall with the end walls requires the employ of separate fastener means, specifically, tension bolts, the elimination of which would result in a desirable simplification of the construction. It is thus an object of the present invention to provide a tub for a washing machine of the radial-loading type having a composite structure including components of different materials, to result in a particularly rational and reliable construction and notably simplified assembly. This object is attained according to the invention by a tub for a washing machine having a circumferential wall formed with a loading opening and sealingly connected to a pair of opposite substantially disc-shaped end walls incorporating respectibe support bearings for a drum mounted for rotation about a substantially horizontal axis. This tub is basically characterized in that the circumferential wall is made of metal while the two end walls are made of a plastic material. Preferably at least one of the end walls is circumferentially welted to the respective rim of the circumferential wall. The characteristics and advantages 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 an axial sectional view of the tub according to the invent#-#n, in combination with-various operating components of a washing machine, figs. 2 and 3 show cn an enlarged scale respective details of the tub of fig. 1 in a preferred embodiment. With reference to fig. 1, a tub is substantially composed of a circumferential wall 1 made of a metal, preferably stainless steel, the opposite rims of which sealingly cooperate with respective disc-shaped end walls 2 and 3 made of a plastic material and incorporating bearings 4 and 5, respectively, for rotatably supporting a horizontal shaft 6 of a washing drum 7. In a per se known manner, the top portion of circumferential wall 1 is provided with a loading opening 13 giving access to the interior of drum 7 after opening a loading hatch 14. Drum 7 is adapted to be rotated by a driving motor 15 secured to end walls 2 and 3 by means of a support bracket 19. The driving power of motor 15 is transmitted by a belt 16 cooperating with a pulley 17 fixedly secured to shaft 6 at the side of the tub corresponding to end wall 2. In particular, #and also with reference to fig. 2, end wall 2 is foremd with an offset rim portion 8 which is secured to the respective rim of circumferential wall 1 by means of bolts 9 or the like, with the interposition of a sealing gasket 10. With reference to fig. 3, end wall 3 is preferably formed with a rim portion 11 of increased wall thickness along which it is welted to the respective rim of circumferential wall 1, with a sealing gasket 12 interposed therebetween. In this context it is to be noted that the welt is executed with a relatively great radius to thereby minimize the stress occurring in circumferential wall 1 at the location of the welt connection. Sealing gasket 12 is accommodated in a groove 20 of rim portion 11 and is eslatically compressed in the radial direction by an annular bead 21 formed in circumferential wall 1 adjacent the respective rim. Bead 21 is pr#ferably formed simultaneously with the welting of circumferential wall 1 onto end wall 3. The elastic compression of sealing gasket 12 by annular bead 21 ensures a liquid-tight seal between the metallic circumferential wall 1 and plastic end wall 3 irrespective of the different thermal expansion coefficient of the two components, even when the tub is subjected to relatively high thermal loads. In addition, the elastic compression of sealing gasket 20 compensates any tolerances and/or imperfections of the contact surfaces between circumferential wall 1 and end wall 3. Similar to the bolted end wall 2, the welt-connected end wall 3 is preferably likewise provided with an integrally formed annular outer rim portion 22. Annular rim portion 22 projects radially outwards and is formed with seats 23 or the like adapetd to receive fastener means 24 for securing operating components of the machine. The annular outer rim portion 22 may thus be used for instance for sec uring thereto bracket 19 for supporting motor 15, brackets for the suspension of the tub by means of resilient elements, friction shock dampener plates and the like. Annular rim portion 22 may additionally be used for securing thereto a per se known device for tensioning transmission belt 16. The tub according to the invention offers various advantages deriving from the above explained characteristics. In particular, the incorporation of bearings 4, 5 in the plastic end walls 2 and 3, respectively, results in a structural continuity between the bearings and circumferential wall 1. The latter has the only function of containing the washing liquid and is not subjected to any substantial mechanical stress, so that it can be made of stainless steel sheet of minimum thickness. On the other hand, circumferential wall 1, being made of metal, does not present any overheating problems otherwise resulting from the operation and the conventional positioning of the heater elements (not shown for the sake of clarity). At the same time, the metallic circumferential wall 1 acts as the only support element for end walls 2 and 3, without the necessity of tension bolts or the like. On the other hand, the end walls, being made of a plastic material, are particularly suited for incorporating in a per se known manner various functional elements such as means for anchoring the suspension springs of the laundering assembly, pressure sensing outlets for pressure switches, support means for equilibre Son weights 18, and the like. The descibed washing tub may obviously undergo numerous modifications. Pulley 17 may thus be disposed adjacent end wall 3, so that the opposite end wall 2 can be readily dismounted for giving access to the interior of the tub. Likewise, the bolts 9 securing end wall 2 to circumferential wall 1 may be replaced by an annular channel-section clamping member.

Claims: Composite Structure Tub for a Washing Machine of theRadial-Loading Type P#atent Claims: 1. A tub for a washing machine having a circumferential wall formed with a loading opening and sealingly connected to a pair of substantially disc-shaped er walls incorporating respective support bearings for a drum mounted for rotation about a substantially horizontal axis, characterized in that said circumferential wall (1) is made of metal while the two end walls (2, 3) are made of a plastic material. 2. A tub according to claim 1, characterized in that said circumferential wall (1) is formed with at least one annular bead (21) adjacent its end for resiliently compressing a sealing gasket (12) interposed between said circumferential wall and a respective end wall (3) connected thereto as by welting. 3. A tub according to claim 1, characterized in that said welt-connected end wall (3) comprises an integrally formed substantially annular rim portion (22) projecting radially therefrom and formed with seat means (23) adapted to receive fastener means (24) for securing operating components (25, 26) of the machine. 4. Atub according to claim 1, characterized in that at least one of said end walls (2, 3) is circumferentially welted to the rim of said circumferential wall (1). 5. A tub according to claim 1, characterized in that each of said support bearings (4, 5) is incorporated in a respective one of said plastic end walls (2, 3). 6. A tub according to claim 1, characterized in that said weltconnected end wall (3) comprises an enlarged rim portion adapted to cooperate with the rim of said metallic circumferential wall (1).

Inventors: PIAI, DINO
Applicants: INDUSTRIE ZANUSSI S.P.A.
Application year: 1986
Main classification: D06F37
IPC codes: D06F37