The present invention relates to a vibration damping device for the oscillation occurring in an oscillating element, which is particularly adequate to be utilized in the washing tub of a washing or drying machine.

Document ES 2387205 B1 shows a vibration damping device for the oscillation in a washing machine. This device allows to damp the oscillation generated by the drum of the washing machine by means of a system comprising a supporting element, an articulating piece and a rotating articulation. This configuration aims at achieving a way to damp the oscillations by means of a rotating damping system. Nevertheless, this configuration is dependent on the mechanical and thermal properties of the pieces it is composed of. Furthermore, this configuration requires voluminous articulating pieces for its operation.

The present invention provides a solution to overcome this technical problem by a damping device and a washing or drying device according to the respective independent claim attached. Preferred embodiments of the invention derive from the dependent claims, from the subsequent description and from the figures of the drawing attached.

A first inventive aspect of the invention relates to a vibration damping device for a washing tub of a washing or drying machine also comprising a housing. This device comprises:

a first articulating piece, with a first end and a second end, the first end of the first articulating piece being provided to be connected to the washing tub in an articulated manner by means of a first articulation that allows rotation around a first rotation axis,

a second articulating piece, with a first end and a second end, the first end of the second articulating piece being connected to the second end of the first articulating piece in an articulated manner by means of a second articulation that allows rotation around a second rotation axis, and the second end of the second articulating piece being provided to be con- nected to the housing by means of a third articulation that allows rotation around a third rotation axis,

in which the first articulation, the second articulation and/or the third articulation is an articulation that provides frictional resistance to rotation, and

in which the first articulating piece and/or the second articulating piece are made of a metallic material. This device gives the advantage of providing an articulating piece with improved mechanical properties, enabling the device to resist higher loads and to reduce the volume of elements that configure the device. The utilization of this damping system in a washing or drying machine leaves free space inside the same, which can be used for different purposes.

In a radial damping device, an articulation that provides frictional resistance to rotation or a friction articulation is to be understood as an articulation in which the friction values during a rotation of the same exceed 10 N, the values ranging preferably from 20 N to 120 N and, more preferably, from 30 N to 60 N.

In a facultative embodiment, the articulation providing frictional resistance to rotation comprises a bushing which is crossable in the rotation axis by a bolt connectable to at least one lug, so that a friction element can be arranged being trapped between the bushing and the at least one lug. In a preferred manner, the bolt is connected to two lugs preferably arranged in a U-shaped configuration, each on one side of the bushing, what makes the structure of the articulation more rigid. Both lugs can clamp the bushing strongly and have a friction element between the bushing and the same. The bushing can be arranged at an end of one of the articulating pieces and, then, the lugs can be arranged at an end of the other articulating piece and/or in the washing tub and/or in the housing, or the bushing can be arranged in the washing tub and/or in the housing and the lugs can be arranged at an end of one of the articulating pieces. With this, the articulation providing resistance to rotation can be arranged in any of the three, i.e. first, second and third articulation, and the disc-shaped friction element can be easily mounted between the lugs and the sides of the bushing.

In a particular case of the preceding embodiment with just one lug at the end of any of the articulating pieces and/or in the washing tub and/or in the housing, the bolt may contain a stop at its protruding end and, between the stop and the bushing, a friction element trapped between them, the friction surface being thereby increased.

In another facultative embodiment, the articulation providing frictional resistance to rotation comprises a bushing which is crossable in the rotation axis by a bolt fixedly arranged at at least one lug, so that a friction element can be arranged being trapped between the bushing and the bolt. In a preferred manner, the bolt is fixedly connected to two lugs preferably arranged in a U-shaped configuration, each on one side of the bushing, what makes the structure of the articulation more rigid. The bushing can be arranged at an end of one of the articulating pieces and, then, the lugs can be arranged at an end of the other articulating piece and/or in the washing tub and/or in the housing, or the bushing can be arranged in the washing tub and/or in the housing and the lugs can be arranged at an end of one of the articulating pieces. With this, the articulation providing resistance to rotation can be arranged in any of the three, i.e. first, second and third articulation, and a bigger contact surface of the friction element with the bushing and the bolt is thereby achieved. Preferably, the friction element is made of a high-compression material, in particular an expanded polyurethane sponge, e.g. from Cellasto ®.

In a further facultative embodiment, the articulating piece made of a metallic material com- prises the bushing integrated therein and/or the at least one lug, forming thereby an articulating piece in just one piece with the consequent advantage when manufacturing.

In yet another facultative embodiment, the articulating piece made of a metallic material is a bent sheet, e.g. of steel, aluminium, stainless steel or the like.

In yet a further facultative embodiment, the articulating piece made of a metallic material is composed of two or more pieces connected to one another. The two pieces can be identical or not. In still another facultative embodiment, the articulating piece made of a metallic material is a shaped wire.

In still a further facultative embodiment, each of the ends of the articulating piece made of a metallic material is wound in the form of a plurality of windings.

In again another facultative embodiment, the second articulating piece is made in one piece of a metal sheet bent on itself, wherein ribs and limiting parts are pre-cut. The sheet is closed on itself with a closure at its ends, in such a manner that the wall thickness of the end of the articulating piece does not increase. These facultative embodiments provide the advantage of an improved series manufacturing, since their manufacturing implies operations easily assumable in an assembly line, such as stamping and bending of metal sheets. A second inventive aspect of the invention relates to a washing or drying machine comprising at least one vibration damping device according to the first inventive aspect.

All features and/or steps of methods described in this specification (including the patent claims, the description and the drawings) can be combined in any combination, except for those mutually excluding combinations of such features.

These and further features and advantages of the invention are now described in greater detail by means of the following detailed description of a preferred embodiment. This embodiment is to be understood as an illustrative and non-limiting example, with reference to the figures of the attached drawing. In particular,

Figures 1 a and 1 b show a particular embodiment of a vibration damping;

Figure 2 shows an alternative embodiment of an articulation of a vibration damping device;

Figures 2a and 2b show an alternative embodiment of an articulation of a vibration damping device;

Figures 3a and 3b show an alternative embodiment of an articulation of a vibration damping device;

Figure 4a shows a first particular configuration of an articulating piece of a damp- ing device;

Figure 4b shows a second particular configuration of an articulating piece of a damping device;

Figure 5 shows a third particular configuration of an articulating piece of a damping device;

Figure 6 shows a fourth particular configuration of an articulating piece of a damping device;

Figure 7 shows a fifth particular configuration of an articulating piece of a damping device;

Figure 8 shows a side and front view of the articulating piece in figure 7; Figure 9 shows the unbent sheet with which the articulating piece in figures 7 and 8 is shaped as well as a side view of the bending process of the sheet to form it; and

Figure 10 shows a feasible configuration of a washing or drying machine contain- ing the vibration damping device.

Figure 1 a shows a particular embodiment of a vibration damping device 1 in a situation of use, installed in a washing or drying machine. In this figure, the following elements can be observed, which form part of this vibration damping device 1 :

- A first articulating piece 2, with a first end 21 and a second end 22. The first end

21 of the first articulating piece 2 is connected to the washing tub 10 in an articulated manner by means of a first articulation 4 that allows rotation around a first rotation axis,

- A second articulating piece 3, with a first end 31 and a second end 32. The first end 31 of the second articulating piece 3 is connected to the second end 22 of the first articulating piece 2 in an articulated manner by means of a second articulation 5 that allows rotation around a second rotation axis, and the second end 32 of the second articulating piece 3 is connected to the housing 1 1 by means of a third articulation 6 that allows rotation around a third rotation axis.

In this particular example of the damping device 1 , the second articulation 5 is an articulation providing frictional resistance to rotation. Furthermore, the first articulating piece 2 and the second articulating piece 3 are made of a metallic material. In other embodiments, only one from the first articulating piece 2 and the second articulating piece 3 is a metal piece.

In this particular example, both the connection between the first end 21 of the first articulating piece 2 and the tub 10 and the connection between the second end 32 of the second articulating piece 3 and the housing 1 1 are articulations provided by corresponding plastic pieces extending through orifices comprised at the ends of the pieces to be connected, said plastic pieces having stops at their ends destined to avoid that the plastic pieces slip out of the orifices.

In a particular embodiment, the metallic piece is the first articulating piece 2. In a further particular embodiment, the metallic piece is the second articulating piece 3. Figure 1 b shows an enlarged illustration of the second articulation 5, in which a lug 12 of the second end 22 of the first articulating piece 2 has been cut out, so that the second articulation 5 can be observed in a greater detail. In this figure, it can be seen how the second articulation 5 is an articulation that provides frictional resistance to rotation. This articulation 5 comprises a bushing 7, which is crossed in the rotation axis by a bolt 8 fixedly arranged at the lugs 12, so that a friction element 9 is arranged being trapped between the bushing 7 and the bolt 8. In this particular case, the friction element 9 is a friction foam, which counteracts rotation between said elements. The friction element 9 needs to be fixedly arranged either at the bushing 7, so that the friction is exerted upon the bolt 8, or at the bolt 8, so that the fric- tion is exerted upon the bushing 7. In this case, the bolt 8 has to be fixedly arranged at the lug 12.

In figure 2, a variant of the particular embodiment illustrated in figure 1 a is shown, in which a detail of the third articulation 6 can be observed, which is an articulation providing frictional resistance to rotation. In this case, this third articulation 6 comprises several lugs 12 fixed to the housing 11 and a bushing 7 corresponding to the second end 32 of the second articulating piece 3, which is crossed in the rotation axis by a bolt 8 connected to the lugs 12, so that a friction element 9 is arranged being trapped between the bushing 7 and the lugs 12. This is an alternative configuration to the configuration shown in the preceding figure, the general functioning of the system being the same in both cases, except for the fact that the resistance to rotation is provided between the bushing 7 and the lug 12 and not between the bushing 7 and the bolt 8. To make friction increase, it is provided that the friction elements 9 can be arranged at the same time between bushing 7 and bolt 8 and between bushing 7 and lug 12. In this case, the friction elements 9 can be made in one piece.

In figure 2a, a variant of the second articulation 5 is shown, which is an articulation providing frictional resistance to rotation. In this case, this second articulation 5 comprises a bushing 7 corresponding to the first end 31 of the second articulating piece 3, which is crossed in the rotation axis by a bolt 8 connected to the lugs 12 placed at the second end 22 of the first articulating piece 2, so that a friction element 9 is arranged being trapped between the bushing 7 and the lugs 12.

Figure 2b shows an enlarged illustration of the second articulation 5, in which one of the lugs 12 arranged at the second end 22 of the first articulating piece 2 has been cut out, so that the second articulation 5 can be observed in a greater detail. In this figure, it can be seen that the second articulation 5 comprises a bushina 7 corresponding to the first end 31 of the second articulating piece 3, which is crossed in the rotation axis by a bolt 8 connected to the lugs 12 arranged at the second end 22 of the first articulating piece 2, so that a friction element 9 is arranged being trapped between the bushing 7 and the lugs 12. Figure 3a shows a variant of an articulation, in this case, the second articulation 5, which is an articulation providing frictional resistance to rotation. In this case, this second articulation 5 comprises a bushing 7 corresponding to the first end 31 of the second articulating piece 3, which is crossed in the rotation axis by a bolt 8 connected to the lug 12 placed at the second end 22 of the first articulating piece 2, so that a friction element 9 is arranged being trapped between the bushing 7 and the lug 12. The own bolt 8 may also have a stop 13 at its protruding end to give more rigidity to the second articulation 5. A friction element 9 is arranged being trapped between the bushing 7 and this stop 13.

Figure 3b shows an enlarged illustration of the second articulation 5, in which the stop 13 is not present and the bolt 8 with the friction element 9 can be seen. In this figure, it can be seen that this second articulation 5 comprises a bushing 7 corresponding to the first end 31 of the second articulating piece 3, which is crossed in the rotation axis by a bolt 8 connected to the lug 12 arranged at the second end 22 of the first articulating piece 2, so that a friction element 9 is arranged being trapped between the bushing 7 and the lug 12.

In figures 4 to 6, several configurations of first articulating pieces 2 made of a metallic material are shown, which could also work as the second articulating piece 3 in any vibration damping device 1. Figure 4a shows a first particular configuration of a second articulating piece 3 comprising an integrated bushing 7. This second articulating piece 3, made of a metallic material by moulding with the bushing 7 integrated therein, allows its coupling to a vibration damping device 1 in a much easier way, since the coupling of the bushing 7 is not required once the piece is manufactured.

Figure 4b shows a second particular configuration of a first articulating piece 2, which is a shaped wire. In this particular configuration, each of the ends of the articulating piece 2 is wound in the form of a plurality of windings 14. However, other configurations are equally feasible in other particular embodiments. This embodiment gives the advantage to allow its manufacturing from an easily achievable material. Furthermore, the length of the articulating piece 2 can be easily varied by coiling the windinas Figure 5 shows a third particular configuration of a first articulating piece 2, which is a bent sheet and gives the advantage consisting in an improved traction and compression behaviour, buckling being thereby avoided. In this configuration, the first end 21 of the first articu- lating piece 2 defines a throughout orifice adequate to form part of an articulation, and the second end 22 of the first articulating piece 2 comprises two lugs 12, one of them containing a screw hole 81 to facilitate the connection to the bolt 8. Furthermore, this piece is achievable by a relatively simple manufacturing method. In a particular configuration of this articulating piece 2, the lugs 12 could clamp the friction elements 9 against the bushing 7.

Figure 6 shows a fourth particular configuration of a first articulating piece 2, which is composed of two parts connected to one another. In this particular example, both parts are symmetrical, although the parts are not completely symmetrical in other particular examples, since it may happen that certain details exist only in one of both halves. These parts can be manufactured by stamping and can be joined together by press fit. In this configuration, the first end 21 of the first articulating piece 2 defines a throughout orifice adequate to form part of an articulation, and the second end 22 of the first articulating piece 2 comprises two lugs 12. In a particular configuration of this articulating piece 2, the lugs 12 could clamp the friction elements 9 against the bushing 7.

Figures 7 to 9 show a particular embodiment of a second articulating piece 3. This articulating piece 3 is made in one piece of a metal sheet bent on itself, as it is shown in figure 9, wherein ribs 35 and limiting parts 36 are pre-cut. The sheet is closed on itself with a closure 34 at its ends, in such a manner that the wall thickness of the end 31 of the articulating piece 3 and the length of the articulating piece 3 do not increase. In figure 7, the ends of the closure 34 can be seen being inserted into one another, but the same closure 34 can be realized as it is shown in figure 8, wherein the closure 34 is bent inwards at the end 31 acting at the same time as a limiting part for the friction element 9 (not shown). As it can be seen in figures 7 and 8, once the sheet has been bent, the ribs 35 are shaped in such a manner that they give structural resistance to the articulating piece 3, so that it does not bend between its ends 31 and 32. The limiting parts 36 bend inwards of the second end 32 to limit the displacement of the friction element 9, so that it remains fixedly placed inside the end 32. To secure the total closure of the sheet, rivets 33 centrally connecting the articulating piece 3 in a non-detachably manner are provided. Such an articulating piece 3 has the advantage with respect to a plastic articulating piece consisting in that it is more resistant having a smaller material thickness and, thereby, its mounting in reduced spaces in the washing machine is facilitated, in particular when it has to be placed very close to the side walls of the machine.

Figure 10 shows a feasible configuration of a washing or drying machine containing at least one vibration damping device 1. In this particular example, a washing tub 10 is shown, which comprises a drum 28 actuated by a motor 25 that transmits the movement to the drum 28 by means of a pulley mechanism 29 fixedly arranged at the drum 28 and connected to the actuating element 25 by a belt 27. Said washing tub 10 is connected to the housing 1 1 by means of suspension elements 17 and two vibration damping devices 1. As figure 10 shows, the vibration damping devices 1 are fixed to the sides of the housing 11 but they could be fixed to the lower part of the housing 1 1 or in parallel to the suspension elements 17 in the upper or lower part of the washing tub 10. A preferred embodiment comprises three damping devices 1 , two of them being preferably arranged at a side of the washing tub 10 and the third of them being arranged at the other side of said washing tub 10. It is also possible to arrange four damping devices 1 , two of them being preferably arranged on each side of the washing tub 10. In figure 10, the advantage of the invention can be clearly observed, since said vibration damping devices 1 according to the invention occupy much less space, what gives additional space to be utilized by the manufacturer or the own user of the washing or drying machine.