The invention relates to a support structure for a piece of furniture with four or more legs, whereby the support structure comprises means which prevent wobbling of the piece of furniture when it is place on an uneven surface.

Wobbling of furniture with four or more legs, particularly tables and chairs, is a common problem that causes quite some annoyance. The best known examples are the tables on terraces. It is almost inherent to a terrace that the surface is uneven. The floor of terraces are often made of bricks or patio tiles that are laid in sand. There may be various reasons for unevenness of terraces, including for example the subsidence of parts of a terrace due to localized compaction of the sand on which the terrace is laid, differences in the dimensions of bricks or patio tiles and sloppy paving work. Whatever the cause may be, the consequential wobbling of tables and chairs is always experienced as undesirable.

Of course it is an option to use a table with only three legs that will always be stable. However, particularly when a bigger table is required, a table with only three legs has disadvantages in terms of stability. For example, the exertion of a downwardly directed force close to a corner of a bigger three legged table may easily result in tilting of the table.

The patent application WO 2007/041725 Al describes a table with pairwise rotatable legs which provides a partial solution. That solution relies on a friction element that impedes rotation of the leg pairs once they rest on a surface, however, it does not exclude this from happening.

The present invention provides a solution which ensures that a piece of furniture with four or more legs, for example a table or a chair, always stands stable on an uneven surface. For the sake of simplicity the examples in this description will be limited to a table. However, the invention explicitly also applies to other pieces of furniture including chairs and other seating furniture. The invention will now be clarified on the basis of six drawings, wherein:

- fig. 1 shows a schematic perspective view of an embodiment of a table

according to the invention;

- fig. 2 shows a schematic perspective view of the support structure of the table shown in fig. 1;

- fig. 3 shows a schematic exploded view of the support structure shown in fig. 2;

- fig. 4a shows a schematic detail of an embodiment of the engagement means of the legs of the table according to the invention;

- fig. 4b shows a schematic detail of an embodiment of the engagement means of the legs of the table according to the invention;

fig. 5 shows a variant of the detail shown in fig. 4a;

- fig. 6 shows a schematic view of the engagement principle of the legs of the table.

In this description and in the drawings identical or functionally similar parts have the same reference numbers.

Fig. 1 shows a schematic perspective view of an embodiment of a table according to the invention, whereby the table comprises four legs.

Fig. 2 shows a schematic perspective view of the support structure of the embodiment of the table shown in fig. 1. The two legs on the right side la and lb shown in fig. 1 have been integrated and constitute a first set of legs and the two left side legs, respectively 2a and 2b, shown in fig. 1 have been integrated and constitute a second set of legs.

Furthermore, this embodiment of the table comprises one central support element 3 of which only a part is shown in fig. 2. In this embodiment the support element comprises a round tube of which the lower end is connected to a curved plate-like element. In the exploded view shown in fig. 3, the curved plate-like element, hereinafter referred to as curved element 4, is shown clearly. In order to connect the sets of legs to the support element 3 the sets of legs comprise engagement means which can engage the curved element 4.

As shown by fig. 4 the engagement means in this embodiment comprise three engagement claws, 5b and 6. For the sake of completeness it has to be mentioned that in this embodiment of the table each set of legs comprises such claws and that a reference to claws with the reference numbers 5a, 5b and 6 is not confined to the claws of one specific set of legs.

The engagement claws 5a and 5b engage the curved element 4 on its top side and the engagement claw 6 engages the curved element 4 on its bottom side.

In the embodiment of the curved element 4 shown in fig. 4 this element is at least substantially smooth, meaning that the curved element 4 does not comprise any protrusions on or recesses in its surface that have been created intentionally.

However, the present invention also includes embodiments of the curved element with raised edges, recesses or grooves, which provide a better engagement between the engagement claws and the curved element.

Fig. 5 shows an embodiment of the curved element 4 wherein the curved element 4 has a raised edge 7 on the top side and whereby this raised edge is meant to partially lock up the claws 5a and 5b that engage the curved element on the top side.

The function of the raised edge 7 will now be clarified further through on fig. 6.

Fig. 6 is a schematic representation of the principle of engagement of the set of legs of the table. For the sake of simplicity the engagement between respectively the claws 5a, 5b and 6 and the curved element 4 is shown partially as a schematic cross section and the claw engaging the top side of the curved element has been given the reference number 5.

In the situation depicted schematically by fig. 6 the set of legs on the left side is positioned on the ground, or at least a force with an upwardly directed component is exerted on the bottom end of the legs, resulting in a clockwise moment that is exerted on the combination of claws, also referred to as claw set, on the left side. Due to the shape and length of respectively the engagement claws which engage the curved element on the top side and the engagement claws which engage the curved element on the bottom side, this claw set will clamp the curved element when a clockwise moment is exerted on it.

In this embodiment the engagement claws 5 on the top side of the curved element are longer than the engagement claw 6 on the bottom side of the curved element. The engagement claws belonging to the claw set of the set of legs on the right side will clamp the curved element when a counterclockwise moment is exerted on them. The of the engaging claws on the right side as schematically depicted in fig. 6, corresponds with the situation that occurs when the legs on the right side are hanging free.

In this situation the set of legs on the right side of the table can rotate in a plane that is essentially perpendicular to the plane of the paper on which the figure is printed since the claws can be moved (slide) along the edge of the curved element without any significant resistance.

When a table with a design that corresponds with the embodiment shown in the figures is lifted, both the set of legs on the left side and the set of legs on the right side will hang free and will hence be able to rotate since the engagement claws can move along the curved element. If subsequently the table is placed on a surface, at some point in time the ends of both legs of a first set of legs will be the first to stand on the surface simultaneously. Consequently the engagement claws of that set of legs will clamp onto the curved element. At that point in time the second set of legs will not yet have the full load on it and will therefore still be able to rotate until both ends of the legs of that second set will also stand on the ground and the engagement claws of that second set of legs will also be clamping onto the curved element. When this happens the four legs of the table will form a rigidly connected set and the table will be stable, standing on four legs on the (uneven) surface.

If the table is lifted up again both sets of legs will assume the free hanging position. Upon subsequent positioning of the table on a surface with a different profile the sets of legs will rotate until the ends of all four legs stand on the surface. Through tilting of the sets of legs the engagement claws will clamp onto the curved element and stability of the table is obtained. Contrary to a few systems according to the prior art that are aimed at preventing wobbling of tables that are placed on an uneven surface, the stability of the table according to the invention does not rely on unpredictable friction forces between components of the table. Nevertheless, the invention includes the option that the engagement surface 8 of the engagement claw 6 and/or at least a strip 9 of the bottom surface of the curved element 4, which make contact with each other when a table is placed on a surface, comprise measures to provide extra friction against rotation of the legs of the table. These measures, hereinafter also referred to as friction augmentation measures, may for example comprise raised edges, serrations or grooves that are created on or in the surface 8 or 9.

In embodiments of the table according to the invention with four legs as discussed so far, the table comprises two sets of legs each set consisting of two legs whereby the sets are connected with each other through engagement claws and a curved element. Apart from ensuring that all four legs can stand on an uneven surface simultaneously, these embodiments also make it possible to ensure that the table top, which usually is mounted perpendicularly to the longitudinal axis of the central support element 3, can be placed in a position of choice, for example an essentially horizontal position.

However, in another embodiment, the table or other piece of furniture according to the invention comprises only one set of legs that is movably connected to the support element of the piece of furniture through engagement claws and a curved element. The other two legs of the four legged table are directly or indirectly rigidly connected to the support element of the table. The set of two movable legs enables stable positioning of this embodiment of the table with all four legs simultaneously on an uneven surface. However, with this embodiment it is not possible to ensure that for example a table top that is rigidly connected with the support element can be placed in a position of choice, for example the horizontal position.

It can be deduced from fig. 6 that when a curved element 4 is applied that does not have a raised edge, a recess or a groove the engagement claws of the respective sets of legs can be slid from the curved element 4 in the longitudinal direction of the curved element, i.e. a horizontal direction coinciding with the plane of the paper on which the figure is printed. By using a curved element 4 with a raised edge such as for example the raised edge 7 shown in fig. 5 this can be prevented. A comparable effect can also be obtained by the application of grooves in the curved element which can engage one or more claws.

In an embodiment the claw set of a set of legs, as shown schematically in fig. 3, fig. 4a and fig. 5 comprises a combination of two engagement claws which engage the curved element on its top side and one engagement claw that engages the curved element on its bottom side. Hence, this configuration involves a three-point engagement, which in principle results in a stable engagement. However, the invention also provides that any other configuration, in terms of the quantity, shape, size and positioning of claws, that is desired or deemed useful can be applied.

Therefore, in the claims a reference to engagement claws 5a, 5b and 6 cannot be construed as a limitation of the number of engagement claws to per se three units. Fig. 4b shows an embodiment in which the engagement means comprise one arcuate engagement claw 5 instead of two engagement claws 5a and 5b.

The invention also includes embodiments in which the engagement claws 5, 5a or 5b on the top side and the engagement claw 6 on the bottom side have been integrated into one component.

It shall be clear from the foregoing that the function of the curved element 4 does not necessarily require a plate-like curved element but can also be fulfilled by any type of curved element with a shape at one or both ends that enables the engagement of a set of claws of a set of legs. Even a piece of curved rod material can in principle be used for this purpose. Therefore, it should explicitly be stated that wherever the term curved element is used in this description and in the claims this is meant to also include curved elements that are able to perform the intended function and that are not made from plate-like material. The support structure of the table according to the invention or parts of the support structure can be made of a wide variety of materials, including polymers, aluminium, steel and stainless steel, such as for example austenitic stainless steel type 304 or 316 In case of metallic versions of the table according to the invention a wide variety of production methods can be selected, including casting.

This description and the figures only highlighted embodiments of the table according to the invention with four legs. However, the table according to the present invention may also comprise more tnan tour legs.

The support structure according to the invention may also be used for pieces of furniture other than tables, such as for example chairs, sofas and other seating furniture. In the above description and in the claims the term table shall be construed to also include any other piece of furniture with four or more legs. All examples given in this descriptive section are intended to be non-limiting, and are provided in order to help in conveying the scope of the invention.