A BASE STRUCTURE FOR ORTHOPAEDIC BEDS OR TEE LIRE DESCRIPTION The invention proposes a base structure for orthopaedic beds or the like, comprising a series of bars made from a material that is rigid or has limited flexibility, the ends of which rest upon yielding supports which allow said bars to follow the conformation of the body.

In particular, the bed base structure according to the invention comprises a series of bars made from wood or a similar material the ends of which rest on two supports which yield in an elastic manner, these supports consisting of two tubes made from flexible material and filled with a fluid of a suitable density, for example, water with substances added in order to regulate the viscosity, so that under the weight of the user, these supports will yield locally where the bars are subjected to the greatest stress and rise where there is no load on the bars, in such a way as to allow the bars to be at different heights, depending on the load to which they are subjected.

In this manner, we obtain an adaptation to the shape of the body and practically equal pressure on all bars.

At present, supports for mattresses, and orthopae- dic mattresses in particular, consist of a series of wooden slats, the ends of which rest on a rigid frame or are attached to same by means of elastic joints.

These slats are made of flexible wood and often are bowed so that under the weight of the user they tend to

flex and bend in the opposite direction.

In these known structures, the pliability is due to the deformation of the loaded slats, which is always limited, and thus during sleep, depending on the position of the sleeper, certain parts of the body are subjected to most of the weight and others are almost completely unloaded.

For this reason, despite the high cost, the results offered by these known structures or"bed bases"are far from optimum.

The present invention now appears in this field, proposing a bed base structure for orthopaedic beds wherein the bed base comprises a plurality of rigid or only slightly flexible bars, the ends of which rest on flexibly yielding supports which consist of tubes made of an elastic material filled with a fluid, so that the body weight is evenly distributed over all the bars which arrange themselves at different heights, following the conformation of the body.

The present invention will now be described in a detailed but not limitative embodiment thereof, with reference to the enclosed drawings, wherein: -figure 1 is a diagrammatically perspective view of a bed base for orthopaedic beds according to the invention; -figure 2 is a cross-section of the end of one bar at the point where it rests upon a respective tube; figures 2a and 2b diagrammatically show the tube of figure 2 in its extended and compressed configurations, respectively; -figure 3 is a cross-section, at the point of

contact with the bar, of a different type of tube which may be used in a bed base according to the invention.

-figure 4 is a cross section, at the point of contact with the bar, of a further different type of tube which may be used in a bed base according to the invention.

With reference to figure 1, the bed base according to the invention, comprises a plurality of bars 1, made of a rigid or only slightly flexible material, which are parallel to one another and the ends of which rest on respective pairs of supports which consist of tubes 2 <BR> <BR> <BR> <BR> <BR> made of deformable material, which may be filled with a fluid of an appropriate viscosity.

The tubes may be made of extruded plastic, stiffened as necessary where required, as will be better illustrated below.

These tubes can be observed more clearly in figures 2 and 3 where they are illustrated in cross-section on a plane orthogonal to the axis.

In particular, the tubes comprise a pair of upper and lower walls 3 and 4 connected by vertical walls which have two inwardly sloped portions 5 and 6, connected to the walls 3 and 4 by two outer curved portions 7 and connected to one another by a final inner curved portion 8.

Essentially, the tube in cross-section is x-shaped.

This configuration is particularly advantageous since it allows the tube to vary in height from a configuration of minimum height, wherein the two sloped wall portions 5 and 6 are almost parallel to the upper

and lower portions 3 and 4, to a configuration of maximum extension wherein the wall portions 5 and 6 come close to an essentially vertical configuration.

These two configurations are illustrated with cross-hatching in figures 2A and 2B, respectively.

When a greater vertical extension is required, the section may consist of two or more"x"shapes one on top of the other, as illustrated in figure 3, with an intermediary horizontal wall 9.

This makes significant upward displacement possible even when dealing with tubes of limited width (in fact vertical extension depends on the length of the portions 5 and 6 of the lateral wall).

The tubes may be filled with an appropriate fluid, such as water possibly with an added substance able to vary its viscosity, so that the liquid acts as a control mechanism, preventing excessive movement of the bars when the sleeper moves.

Numerous experiments carried out have made it possible to check the opportuneness of stiffening the sloping wall portions 5 and 6, for example by coextruding strips of material with limited flexibility, in order to prevent the side walls from deforming and coming out at the sides as a result of internal pressure when the tube expands upward.

The straight portions of the wall should therefore preferably be more rigid than the curved portions 7 and 8.

In use, the bars which are initially subjected to the greatest load will fall together with the respective portion of the support, while the bars which are subject

to the lightest load will rise since the tube in that area will expand upward because of pressure from the internal fluid.

It may also be possible to make tubes with different elasticity at the points which are generally subject to a lighter load.

In fact, most of the body weight is exerted at the thorax, while the weight is considerably less in the area of the lower limbs.

For this reason, to prevent the bars in this area from rising excessively, tubes of different elasticity may be provided, for example, by applying elements which increase the rigidity of the structure at the curved connectors 7 and 8 as well.

The embodiment of fig. 4 differs form that of fig.

3 in that each support comprises a plurality of superimposed closed chambers or tubes 2G separated by horizontal walls 9'.

Within the scope of the present invention, different embodiments may be conceived, and, in the same way, both the dimensions and materials employed may vary according to the requirements in use.