EP0132805B1

EP0132805B1 - Stainless steel tub for a laundry washing machine

Info

Publication number: EP0132805B1
Application number: EP84108623A
Authority: EP
Inventors: Dino Piai
Original assignee: Industrie Zanussi SpA
Current assignee: OFFERTA DI LICENZA AL PUBBLICO
Priority date: 1983-07-29
Filing date: 1984-07-20
Publication date: 1989-04-26
Also published as: DE3477944D1; ES280392Y; IT8345721A0; EP0132805A2; EP0132805A3; ATE42588T1; ES280392U; IT1174950B; IT8345721A1

Abstract

A stainless steel tub (10) for a domestic laundry washing machine (8) of the top-loading type comprises a cylindrical peripheral wall (14), two lateral end walls (15, 16), support means (23, 28, 38, 25, 41) for the tub-drum assembly (10, 11), suspension elements (12, 13), and equilibration counterweights (31, 32). On one side of the tub (10), said support means are secured to a stiffener ring (20) itself secured to the peripheral wall and a respective end wall (16), while on the other side of the tub, they are secured to edge portions of the peripheral wall (14) and the other end wall (15) by means of bolts (26) clamping said edge portions together with a sealing gasket (27) interposed therebetween.

Description

The present invention relates to a stainless steel washing tub for a domestic laundry washing machine of the top loading type.
The type of laundry washing machines defined above is normally provided with a metal tub substantially composed of a cylindrical peripheral wall adapted to surround a rotating drum and formed with an opening for access to the drum, and a pair of circular end closure walls welded or mechanically secured to the edges of the peripheral wall.
Welded to the outer periphery of a tub of this type are metal lugs adapted to be engaged by elements employed in the suspension and equilibration of the tub and for dampening the oscillations thereof during operation of the machine. In this manner the tub of this type performs not only the functions of a container, but also the functions of a structural member for engagement with the named elements.
This implies that all of the components of the washing tub have to be formed with a considerable wall thickness so as to be able to absorb the considerable mechanical loads to which the washing tub is subjected during shipping and operation of the laundry washing machine.
On the other hand, it is evident that the described construction is rather expensive due to the considerable amounts of stainless steel required for assembling the tub.
In addition, the above described construction of the washing tub involves the formation of numerous weld seams which may give rise to the occurrence of corrosion and thus to a progressive degradation of the material of the tub and its components, resulting in a reduction of their mechanical strength.
From FR-A-1 215 057 a tub for a washing machine is known having a U-shaped peripheral wall and two end closure walls which are semicircular in their lower portions and rectangular in their upper portions. The document discloses two basic embodiments of interconnections of the peripheral wall and the end closure walls. In both of the basic embodiments the end closure walls and the peripheral wall comprise extensions directed either parallelly to the axis of a drum to be housed in the tub or parallelly to the end closure walls. A sealing gasket is interposed between said extensions. According to the first embodiment the interconnection between the respective walls is effected by crimp seaming, according to the second embodiment the interconnection is effected by means of bolts. In either case, the location of interconnection is separated from the cavity defined by the tub by means of said sealing gasket.
From DE-A-2 719 336 a washing machine of the front loading type is known having a tub in which the peripheral wall and one end wall comprise axially extending annular extensions which are welded together at the end portions thereof. The peripheral wall comprises a peripheral, inwardly projecting bead which contacts the apex between the axially and radially extending portions of the end wall. A space is defined between the peripheral wall the end wall in the portion between the bead and the weld seam which space is filled with a sealing material so that the weld seam is insulated from the washing liquid in order to avoid corrosion. To the extended portion of the peripheral wall and of the end wall a spider is secured by means of bolts which spider is adapted to mount the drum within the tub.
From DE-A-2 633 604 a tub for a washing machine of the front loading type is known in which a peripheral wall and an end wall are interconnected with each other by means of a resilient filling gasket. A mounting ring is mounted to said assembly by means of a clamping ring of u-shaped cross-section which engages a projecting annular portion of the peripheral wall and a respective counter portion of the mounting ring, said portions sandwiching the sealing gaskets therebetween. A spider for mounting a washing drum is secured to afore-mentioned mounting ring.
The present invention has for its object to provide a stainless steel washing tub for a laundry washing machine of the top-loading type constructed so as to relieve the peripheral wall and the end walls of the tub of any functions as a carrying structure for the elements used in the suspension and equilibration of the tub and for dampening the oscillations of the components participating in the laundering process, and to thus enable the peripheral wall and the two end walls to be dimensioned for solely carrying out a function as a container for the washing drum and the washing liquid.
According to the invention, these and other objects are attained by a stainless steel washing tub for a domestic washing machine of the top-loading type, comprising a cylindrical peripheral wall formed with an opening for access to a rotatable washing drum, and a pair of end closure walls secured to respective lateral ends of said peripheral wall, as set forth in claim 1. Preferred embodiment of the invention are subject matter of the dependent claims.
The tub comprises support means adapted to connect the tub to upper and lower suspension elements within the machine and for mounting the drum and the counterweights for dynamic equilibration. First support means are secured to one side of the tub by means of a stiffener ring projecting outwards of the tub and secured thereto adjacent the junction between the peripheral wall and one of the end closure walls. Second support means are secured at the other side of the tub to bent edge portions of the peripheral wall and the other end closure wall, with the interposition of a sealing gasket therebetween. Third support means are secured to both sides of the tub in combination with the said first and second support means.
According to the invention, the elements used in the suspension, for equilibration and for dampening oscillations of the tub are connected to two metallic plate members secured respectively to the sides of the tub for absorbing the mechanical loads exerted during transport and operation of the laundry washing machine.
The construction of a tub of this type does not require any welding operations for securing connection lugs or similar elements as is the case in the presently employed manufacturing methods.
As a result, the tub according to the invention may advantageously be formed of stainless steel components having considerably reduced wall thickness, offering at the same time the advantages of improved resistance against corrosion and improved operational reliability.
The characteristics of the invention will become more clearly evident from the following description, given by way of a non-limiting example with reference to the accompanying drawings, wherein:

fig. 1 shows a longitudinally sectioned view of a tub according to the invention as mounted in a laundry washing machine,
figs. 2 and 3 show enlarged longitudinal sectional views of respective structural details of the tub shown in fig. 1, and
figs. 4, 5 and 6 show elevational front side views of three different embodiments of the tub according to the invention.

With reference to fig. 1, there is shown a domestic laundry washing machine 8 of the top-loading type, comprising a housing 9, a washing tub 10 and a washing drum 11 rotatably mounted within tub 10, the latter being mounted within housing 9 by means of resilient upper suspension elements 12 and lower vibration dampener elements 13. At this particular instance, tub 10 is formed of stainless steel sheet of reduced wall thickness and comprises a cylindrical peripheral wall 14 and a pair of lateral end closure walls 15 and 16 secured to peripheral wall 14 and formed with a central opening 17 and 18, respectively, for passage therethrough of the end portions of a shaft 19 carrying drum 11.
Shown in figs. 2 and 3 on an enlarged scale are details of the junction between peripheral wall 14 and a respective one of end closure walls 15 and 16. As evident from fig. 3, end wall 16 is secured to peripheral wall 14 together with a circular stiffener ring 20 formed of a base metal and having a greater wall thickness than peripheral wall 14 and end closure walls 15 and 16, as specified above.
In particular, stiffener ring 20 is formed to present a cross-sectional shape including a planar portion 21 projecting outwards of tub 10 and a bent portion 22 crimped onto the similarly crimped edge portions of peripheral wall 14 and end wall 16, with suitable sealing elements (not shown) interposed therebetween. Adjacent the other side of tub 10, the edge pcrtions of end wall 15 and peripheral wall 14 are in contact with one another, with a sealing gasket 27 interposed therebetween, and clampingly retained between an edge portion of a metal support plate member 23 (figs. 1 and 2) and a bar 25 provided for connecting the tub, and thus the drum contained therein, to the lower vibration dampening elements 13. The above named members are each provided with openings for the passage of fastener elements 26. In particular, the peripheral edge portion of end wall 15 projects outwards of the tub and is of L-shaped cross-sectional ccnfig- uration adapted to accommodate the above mentioned sealing gasket 27, itself of triangular cross-sectional shape, while the edge portion of peripheral wall 14 is of a complementary cross-sectional shape including an outermost portion extending parallel to that of end wall 15 and an inwards adjacent inclined portion cooperating with an inwards directed angle of the edge portion of end wall 15 to enclose and compress sealing gasket 27 retained therebetween.
This sealing gasket has a substantially triangular cross-sectional shape adapted to substantially fill the interstice between the edge portions of peripheral wall 14 and end wall 15 when compressed therebetween by the action of the inclined portion of peripheral wall 14 and the tightening of fastener element 26.
Analogously to stiffener ring 20, support plate member 23 is made of a base metal and is substantially flat, with a central reentrant portion provided with a circular opening being formed opposite central opening 17 of end wall 15. A further metal support plate member 28 similar to plate member 23 is bolted to the stiffener ring 20, with another leg 24 of bar member 25 interposed therebetween, stiffener ring 20 itself being secured to peripheral.wall 14 and end wall 16 of tub 10, as explained above. The portions of support plate member 28 engaging stiffener ring 20 are formed with an outwards offset profile 30 having an end portion adapted to contact planar portion 21 of stiffener ring 20 and to be secured thereto by means of fastener elements 29 such as rivets, bolts or the like.
Support plate members 23 and 28 are preferably of triangular shape as shown in fig. 4, and dimensioned so as to be able to effectively support the tub-drum assembly and/or respective counterweights 31, 32 formed for instance of a cement compound and provided for the dynamic equilibration of the assembly. Crimped to the inwardly bent rim portion 33 of the central opening of each plate member 23 and 28, with the interposition of suitable sealing elements (not shown), is the corresponding inner edge portion of the respective end wall 15 or 16, so as to ensure hermetic sealing of the tub 10. At the location of the central reentrant portion of each plate member, a support collar 34, 35 is bolted to the outer side of the respective plate member for accommodating a respective bearing of the shaft 19 carrying drum 11. Adjacent its upper end each triangular plate member 23, 28 is formed with a throughopening 36 (fig. 4) for connection thereto of a respective one of the above mentioned upper suspension elements 12, while the intermediate portions of each plate member between the apices thereof and the central opening are formed with three openings 37 permitting the dynamic equilibration counterweights 31, 32 to be secured thereto. As an alternative to the triangular shape of the plate members shown in fig. 4, the plate members, which may for instance be made of aluminum, may be of a three-armed star-shaped configuration as shown in fig. 5, and integrally formed with the bearing support collars described above. In another embodiment shown in fig. 6, the plate members may be formed of cast iron, in which case they may assume the additional function of dynamic equilibration elements.
Diagrammatically shown in figs. 3 and 4 is also the lower part of the tub according to the invention, whereat a forward bar 38 and a rearward bar 25 are secured on one side of the tub.10, to the planar portion 21 of stiffener ring 20 and, on the other side of the tub 10, to the edge portion of peripheral wall 14 by means of bolts or the like for connecting the tub-drum assembly to the vibration dampener elements 13. The forward bar 38 additionally cooperates with the support of a motor 40 driving drum 11, together with a lug 41 located adjacent rearward bar 25 and permitting the tension of a transmission belt to be adjusted.
Projecting in a downward direction towards the lowermost part of the laundry washing machine from the central portion of each bar 28 and 23 is a lug 42 adapted to cooperate with the respective vibration dampener element 13 secured to the bottom of the machine for dampening the vibrations of the tub-drum assembly.
Also shown in fig. 1 is a belt drive connection between a pulley 46 of motor 40 and a pulley 48 releasably secured to shaft 19 for rotating drum 11. The end portion of tub 10 facing towards the described drive connection, i.e. the end portion thereof formed of plate member 23 and end wall 15, is capable of being disassembled by releasing the respective bolted connections between the various components for giving access to the interior of the tub-drum assembly.
From the above description it is evident that the tub 10 according to the invention permits considerable savings of stainless steel to be achieved thanks to the fact that the function of structural carrying members is taken over by the stiffener ring 20 and the support plate members 23 and 28. In addition, the assembly of the entire tub-drum assembly does not require any welding operations to be carried out, the assembly being accomplished by simple crimping operations and by means of fastener elements in the form of bolts and nuts or the like. As a result, the invention eliminates the danger of corrosion of the tub 10 and permits the assemby thereof to be carried out by largely automatized manufacturing procedures.
In addition, the tub according to the invention facilitates the inspection of the interior of the tub and the replacement of any parts found to be defective on such inspection.
It is finally to be noted that the method for assembling the tub 10 according to the invention may be readily employed, with the requisite modifications, for the assembly of washing tubs of other types of laundry washing machines or laundry dryers currently assembled by traditonal methods.

Claims

1. A stainlees steel tub for a domestic laundry washing machine of the top-loading type, comprising a cylindrical peripheral wall (14) formed with an opening for access to a rotatable drum (11,), and two end closure walls (15,16) secured to lateral edges of said peripheral wall (14), first and second support means (28, 23) being provided for connecting the tub (10) to upper and lower suspension elements (12, 13) of the machine (8) and for supporting the drum (11) and at least one dynamic equilibration counterweight (31, 32), said peripheral wall (14) and said end closure walls (15, 16) having extension at the edge portions thereof extending to the outside of said tub (10) and essentially parallel to the rotational axis of said drum (11) and being fixedly connected to each other, wherein said first support means (28) is secured to one side of said tub (10) by means of a separately prepared stiffener ring (20) projecting outwards of said tub (10) and being fixedly connected thereto by including it into the interconnection of said peripheral wall (14) with a respective end closure wall (16), and said second support means (23) is secured to the other side of said tub (10) adjacent bent edge portions of said peripheral wall (14) and the other end closure wall (15), a sealing gasket (27) being interposed between said peripheral wall (14) and said other end closure wall (15), and wherein third support means (25, 38) are secured to said stiffener ring (20) together with said first support means (28) and to the interconnected edge portions of said peripheral (14) and said other end closure wall (15) together with said second support means (23), said third support means (25, 38) being adapted to be connected to vibration damper elements (13).

2. A tub according to claim 1, characterized in that said stiffener ring (20) comprises an angularly bent portion (22) crimped onto correspondingly crimped edge portions of said peripheral wall (14) and said end wall (16), and a planar portion (21) projecting outwards of said tub (10) for permitting said second and third support means (25, 38) to be secured thereto.

3. A tub according to claim 1 or 2, characterized in that the edge portion of said other end wall (15) is formed with an L-shaped profile projecting outwards of the tub, and that the adjacent edge portion of said peripheral wall (14) is likewise formed with a substantially, L-shaped profile having an inclined portion cooperating with an inner angle of the edge portion of said other end closure wall (15) for enclosing and compressing said sealing gasket (27) disposed therebetween with the aid of a system of bolts (26) fixedly interconnecting said second support means (23), said other end closure wall (15) and said cylindrical peripheral wall (14).