The present invention concerns a piece of furniture.

In particular, the invention concerns a chair, a table, a desk or the like.

It is known for chairs to be built according to a modular system whereby the frame and the seat can be selected independently by a user and can be connected to one another .

It is customary thereby to provide openings in the frame and to provide a plate on the bottom side of the seat or to integrate a plate in said bottom side, such that the frame and the plate can be connected by means of screws.

A disadvantage is that the screws may come off after a while, which is detrimental to the stability of the chair and more generally of the piece of furniture.

Another disadvantage is that during the transport of pieces of furniture, it may be necessary to detach frames, seats, tabletops and the like from one another.

Thus, all parts and all frames which are identical in shape can be stacked onto one another, thus reducing the volume to be transported to a minimum. A disadvantage is that unscrewing pieces of furniture and subsequently screwing the pieces of furniture together again is a labour-intensive operation.

Another disadvantage is that the screws are loose elements and consequently can get lost easily, for example during a removal or during transport.

The use of such pieces of furniture that are screwed together in a school environment or in pieces of furniture designed for children has even more disadvantages, however, and hence is less appropriate.

For it is known that children like to fumble with things, including the bottom sides of their chairs or tables, or that children, by way of a joke, may partly dismount pieces of furniture.

A disadvantage is that conventional screws are easy to loosen, such that the piece of furniture is made less stable, which of course is potentially hazardous for the children.

A disadvantage related thereto is that the piece of furniture is temporarily useless and needs to be screwed together again.

Another disadvantage is that the children may harm themselves when fumbling with the screws.

There is also the risk that a child may entirely loosen one or several screws. A disadvantage is that the piece of furniture may entirely collapse, whereby the child may get hurt.

Another additional disadvantage is that, especially with little children, there is a risk that the child may swallow the loosened screw or screws.

The present invention aims to remedy one or several of the above-mentioned and/or other disadvantages by providing a piece of furniture having a part such as a table top or a seat, whereby the part is fixed to the tube of a frame, whereby the part concerned is provided with a groove with which the part can be provided over the tube and whereby the groove has a slanting, continuous wall on one side of the tube with a guiding groove in it, and a shorter wall on the other side of the tube confined by a cam with an undercut directed towards the tube, whereby the part is fixed to the tube concerned by means of at least one clamping block which fits over the tube, whereby the clamping block is provided with a guiding block on one far end which is held in a sliding manner in the above- mentioned guiding groove and whereby the clamping block is provided with a profile on the other far end which works in conjunction with the above-mentioned undercut so as to clamp said clamping block by shifting it axially over the tube up to the cam.

An advantage is that the part and the frame can be easily fixed to one another, such that the piece of furniture is easy to realise and can also be easily dismounted. An additional advantage is that no special tools are required for the mounting or dismounting.

The frame is preferably fixed to the part without any screws being required.

An advantage is that all the disadvantages related to the use of screws are avoided. Thus, it is excluded that children may hurt themselves to the screws, or that screws may get lost, or that children swallow any screws or the like.

In a first embodiment of the invention, the part and the frame are connected in such a way that the part and the frame can be easily detached from one another.

To this end, one only has to shift the clamping block in the axial direction of the tube, but in the opposite sense as when fixing the parts.

An advantage of this embodiment is that the piece of furniture can be easily dismounted during transport, in view of a removal or the like.

Yet another advantage is that the frame can be re-used with another part.

Thus, when the piece of furniture concerns a chair for example, the seat will wear faster, get soiled faster or will have to be replaced sooner than the frame. The invention also gives the user the opportunity for example to transform a stool into a chair by replacing the part .

The invention is also particularly safe for children.

Indeed, the risk for children to hurt themselves to the clamping block is very small, given the design and finish of the clamping block.

The clamping block also has larger dimensions than a screw, so that there is practically no risk of the clamping block being swallowed.

Although these modular possibilities naturally offer many advantages, applications may be conceived whereby said easy dismounting is less desirable. In this case, means may be provided which prevent an unwanted shift of the clamping block.

In a practical embodiment of the invention, said means consists of an opening in the tube of the frame on the one hand, and a flexible lip with a cam on the clamping block on the other hand, such that when the clamping block is shifted in the axial direction of the tube, the cam automatically snaps in the opening and thus prevents any shifting in the opposite direction.

This offers the advantage that a child cannot accidentally dismount the piece of furniture, so that any risks related thereto are excluded.

Another advantage is that no specific tools are required.

In order to better explain the characteristics of the invention, the following preferred embodiment of a piece of furniture according to the invention is described by way of example only, without being limitative in any way, with reference to the accompanying drawings, in which: figure 1 schematically represents a piece of furniture according to the invention;

figure 2 schematically represents an exploded view of the piece of furniture from figure 1, seen in perspect ive ;

figure 3 shows the detail indicated by F3 in figure 2 larger scale;

figure 4 shows a view according to arrow F4 in figure

2;

figure 5 schematically represents a clamping block seen in perspective;

figure 6 is a side elevation of the clamping block from figure 5;

figure 7 shows the piece of furniture from figure 1 in perspective, whereby the clamping blocks are omitted; figure 8 shows a detail F8 from figure 7, after the clamping blocks have been applied. Figure 1 schematically shows a piece of furniture 1 in the shape of a chair with a frame 2 and a part 3 in the shape of a seat shell or seat.

The frame 2 as represented is thereby of the type formed of four legs 4 which are connected by means of tubes.

In particular, the frame 2 as represented thereby comprises a tubular system in the shape of a rectangular support 5, built of three parallel, practically equally long tubes 6-8 which are connected at their far ends by means of two connecting tubes 9, as is illustrated in figure 2.

In the given example of figure 2, the above-mentioned tubes 6-8 have different diameters, and more specifically the inner tube 7 is made thinner than the two outmost tubes 6- 8.

Although the given figures show tubes 6-8 with a circular section, this is not strictly required according to the invention, and the tubes 6-8 can be made as hollow or full rods.

Figure 2 also shows the side of the part 3 which is fixed to the frame 2. In the case of the chair, this regards the bottom side of the seat or seat shell, either or not made of a synthetic material .

According to the invention, part 3 is provided with at least one groove 10, as is shown in more detail in figures 3 and 4. In the given embodiment, said groove 10 is confined by a wall 11 on one side extending over a length A on the bottom side of the seat 3.

Said wall 11 is directed somewhat slantingly, but this is not strictly necessary according to the invention.

In said slanting wall 11 is provided a guiding groove 12 extending over a length B, whereby the length B is somewhat smaller than the length A of the slanting wall 11, such that the guiding groove 12 is confined by two end walls 13.

Opposite said slanting wall 11 and on the other side of the groove 10 are provided two cams 14 in the given embodiment in the shape of two shorter walls 14, situated at the far ends of the guiding groove 12.

In the given example, the groove 10 is limited by the slanting wall 11 on one side and by the cams 14 on the other side, situated at a distance C from one another, such that a free space 15 is created between the two cams 14.

According to the invention, the groove 10 can be limited by a single cam 14, formed of a shorter wall, whose width D is smaller than the length A of the slanting wall 11.

Naturally, it is not excluded to provide more than two cams 14.

The above-mentioned cams 14 are preferably made somewhat block-shaped .

In the most preferred embodiment, the guiding groove 12 is positioned in such a manner in the slanting wall 11 that it is not only situated opposite the cam 14 or cams 14, but such that it also continues on at least one side past the width D of the cam 14.

In the most preferred embodiment, the width D of the cams 14 is smaller than half the length A of the slanting wall 11 and even smaller than or equal to one third of said length .

In the wall 16 of the cam 14 which is directed towards the groove is provided an undercut 17 according to the invention, as indicated in figure 3.

Said undercut 17 preferably has such a shape that it connects to the shape of the tube 6.

In the given example, the cam 14 has an undercut 17 in the shape of a bow segment having a certain length, whereby the radius of the bow segment is equal to or somewhat larger than the radius of a tube 6 of the frame 2.

In a practical embodiment of the invention, the seat of the chair is realised by means of a blowing mould, and the part 3 with the cam 14, the wall 11 and the groove 10 form an integrated whole, and they are made as a single structure out of a synthetic material. In the given example, the seat is supported by two additional tubes 7-8 being held in corresponding additional grooves 18-19, running parallel to the first-mentioned groove 10.

Said additional grooves 18-19 have such a shape that the tubes 7-8 concerned are being held in a close-fitting manner in said additional grooves 18-19, and such that the grooves 18-19 are confined on one side by a lip 20 whose profile corresponds to the undercut 17 of the above- mentioned cams 14, and whereby said grooves 18-19 are directed slantingly in relation to the bearing face 5 of the frame 2 in this manner. Naturally, it is possible to provide some extra grooves in the frame 2 for fixing additional tubes.

By putting several tubes 6-8 in grooves 10,18,19 and by selecting the shape of the grooves 10,18,19 and tubes 6-8 such that they fit closely to one another, this offers the advantage that there is no play between the frame 2 and the seat 3.

Moreover, such a multiple fastening with close-fitting elements results in a piece of furniture 1 which can resist large forces, since the forces are distributed over a large surface and the pressure exerted remains acceptable.

Figure 5 schematically shows a clamping block 21 seen in perspective. According to the invention, the clamping block 21 is provided with a guiding block 23 on one far end 22 which can be held in a sliding manner in the above-mentioned guiding groove 12 and which is provided with a profile 25 on the other far end 24 working in conjunction with the above-mentioned undercut 17 in the cam 14.

In the given example, the clamping block 21 has a somewhat rectangular base surface 26, and one far end 24 of the block 21 is provided with a bent wall 27 which is adjacent to one of the sides of said base surface 26.

The outer contour of said bent wall 27 has a shape which practically coincides with the undercut 17 in the cam 14, such that the wall 16 of the cam 14 and said bent wall 27 of the clamping block 21 are complementary.

The two sides of the base surface 26 which are adjacent to said bent wall 27 are each provided with a straight wall 28 in which is provided a recess 29 whose shape is preferably selected such that a tube 6 of the frame 2 can be provided in a close-fitting manner in said recess 29.

From what precedes, it is clear that the clamping block 21 described by way of example has a hook-shaped profile with a locking section 27 on the outside whose shape corresponds to the shape of the undercut 17, and a locking section 29 on the inside whose shape corresponds to the tube 6. In the given example, the guiding block 23 is provided on a slanting side 30 of the clamping block 21 and said slanting side 30 can co-operate in a shifting manner with the slanting wall 11 of the groove 10 in the part 3.

The hook-shaped part of the clamping block 21 is preferably such that, if the clamping block 21 is provided in the guiding groove 12 with the guiding block 23, the clamping block 21 can be snapped on the tube 6.

In the given example, the width E of the clamping block 21 is practically equal to the width D of the cam 14, and the width E is preferably selected smaller than the distance C between the cams 14; in particular, in the given example, the distance C is about twice the length E of the clamping block 21.

In the most preferred embodiment of the invention, additional means 31 are provided which have to prevent the clamping block 21 from shifting in the axial direction in an unwanted manner.

In the given example of figure 6, a flexible lip 32 is provided to that end on the inside of the bent wall 27, whereby said lip 32 is provided with a cam or a thickened end 33 on its far end, and whereby a recess 34 is further provided in a tube 6 of the frame 2.

It will be clear to the professional that the dimensions, the position and the shape of the cam 33 on the lip 32, as well as the recess 34 in the tube 6 should be selected more or less in relation to one another. The method for fixing the part 3 on the frame 2 by means of one or several clamping blocks 21 is very simple and as follows . In a first stage, represented in figure 7, the frame 2 is put against the bottom side of the seat 3 with tubes 6-8.

One or several tubes 6-8 are hereby put in the grooves 10,18-19 provided to that end on the bottom side of the seat 3.

The shape of the grooves 10,18-19 and the circumference of the tubes 6-8 thereby make it possible to guarantee that the tubes 6-8 fit in the grooves 10,18-19.

In a following stage, a first clamping block 21 can be provided .

The clamping block 21 is hereby provided over the tube 6 in such a manner that the guiding block 23 of the clamping block 21 is situated in the guiding groove 12 of the seat 3.

It is clear that the clamping block 21 can only be snapped on the tube 6 in places 15 where the groove 10 is merely confined by the slanting wall 11.

In the given example, this means that the clamping block 21 cannot be provided at one of the cams 14, but that it should be placed in the free space 15 between the two cams In that condition, the inside of the clamping block 21 will be clamped in a close-fitting manner round the tube 6. Next, the clamping block 21 can be shifted axially according to the direction of the tube 6, in particular in the direction of one of the cams 14.

During said movement, the guiding block 23 shifts in the guiding groove 12 of the seat 3 and the inside of the clamping block 21 shifts over the outer perimeter of the tube 6.

After a certain displacement, the clamping block 21 ends up at the cam 14, whereby the profile of the clamping block 21 makes sure that the far end 22 fits tightly or in a practically clamping or fitting manner in the space between the tube 6 and the undercut 17 in the cam 14, so that, as a consequence, some resistance may be felt during any further displacement.

In the given example, the clamping block 21 can be shifted into an end position in which the transversal walls 35 of the cam 14 and the walls 28 of the clamping block 21 are situated in each other's extension.

The position and size of the guiding block 23 and the length B of the guiding groove 12 are preferably selected such that, in this end position, the guiding block 23 ends up to the end wall 13 of the guiding groove 12. Thus, said end wall 13 forms a stop to the guiding block 23 and any further axial shifting of the clamping block 21 will be prevented. Preferably, after a first clamping block 21 has been provided, a second clamping block 21 is provided in a similar manner and it is shifted up to opposite the second cam 14, as illustrated in figure 8. From what precedes it is clear that the use of a clamping block 21 makes it possible to realise the connection between the frame 2 and the seat, or more generally the part 3, without any screws being required. It is clear that, after said fastening, the clamping block 21 will be directed with its flat side 26 to the frame 2, and that it will not form an additional protruding element on the bottom side of the part 3. In a preferred embodiment whereby the clamping block 21 is provided with a flexible lip 32, the fastening is done in a similar manner, but when the clamping block 21 is placed over the tube 6, the lip 32 will be pushed away by the tube 6 towards the inside of the bent wall 27, or in other words in the cavity of the clamping block 21 which is enclosed by the bent wall 27.

When the clamping block 21 is then axially shifted, the lip 32 will shift with its cam 33 over the outer perimeter of the tube 6. At the opening 34 in the tube 6, thanks to the spring force of the lip 32, the cam 33 will snap in the opening 34 of the tube 6 and thus provide for a permanent fastening of the frame 2 and the part 3.

Naturally, the opening 34 in the tube 6 is selected such that the cam 33 meshes in the opening 34 when the clamping block 21 is situated in the end position, whereby the walls 28 of the clamping block 21 and the cam 14 are situated in one another's prolongation.

Also other means to prevent any unwanted axial shifting of the clamping block 21 can be provided on the piece of furniture 1.

Although, in the given figures, the frame 2 and the part 3 are always fastened by means of two clamping blocks 21, it is clear that the invention is not restricted thereto. Although, in the given figures, a chair is always represented as an embodiment, the invention can also be used for other seating furniture or other pieces of furniture such as tables or the like, whereby a part 3, such as a tabletop, a seat shell or the like, is fixed on a frame 2.

It is also possible to use several clamping blocks 21 to fix several parts 3 on one common frame 2 so as to form a bench, for example, with seat shells situated next to one another. The figures always show a frame 2 of the type with four legs, but it is also possible to use a frame 2 with a single leg according to the invention, or a frame in the shape of a leg with wheels.

The present invention is by no means restricted to the embodiments described by way of example and represented in the accompanying drawings; on the contrary, such a piece of furniture according to the invention can be made in all sorts of shapes and dimensions while still remaining within the scope of the invention.