"DOUBLE-STRUCTURE STAIR"

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FIELD OF THE INVENTION

The present invention concerns a double-structure fixed stair, provided with a plurality of steps and generally assembled inside closed environments, such as for example domestic environments, public or private offices, or other, to connect two stories together. In particular, the stair according to the present invention is of the modular type, that is, formed by a plurality of modules assembled together, in which each module substantially consists of two structural support elements connected to each other by a relative step.

BACKGROUND OF THE INVENTION

Double-structure fixed stairs are known, in which the steps rest on and are supported from below by two lateral supporting structures, which also function as a bearing element for the stair once it has been fixed to the walls. Double-structure fixed stairs are also known which are formed by a plurality of modules, in which each of the modules comprises at least:

- a first supporting plate;

- a second supporting plate specular to the first and disposed substantially parallel to it; - one or more transverse connection elements between the first supporting plate and the second supporting plate; and

- a step disposed resting, and fixed with screws, on the two supporting plates.

In known modular double-structure stairs, the bearing structure therefore consists of the two plates and by one or more transverse connection elements, whereas the steps are only functional for a user to go up or down the stair.

In particular, both the first and the second supporting plate are made by shearing, pressing, laser cutting or plasma cutting, or other cutting techniques for metal material of reduced thickness, such as metal sheet or suchlike.

The two supporting plates of known stairs are substantially L-shaped rotated by 90° to the left, that is, in the assembled condition, they each have a first substantially horizontal segment, or tread segment, and a second substantially vertical segment, or riser segment, extending upwards from an upper edge of the tread segment.

The first and second supporting plate are also provided with a supporting fin for the step. The fin is made in one piece and is co-planar along the upper edge of the tread segment in a position near the riser segment; it is then bent mechanically with respect to the tread segment along the upper edge, to define the supporting plane of the step.

However, the conformation of the supporting plates, with the fin near the riser segment, generates various disadvantages during the bending steps of the latter, since accidental bends or breaks of the riser segment can occur, both direct, that is, due to a wrong positioning of the bender, and also indirect, that is, due to the elastic deformation proper of the material.

This disadvantage normally entails a high number of discarded plates after bending, entailing a consequent increase in the production costs of the stair.

Furthermore, in known double-structure modular stairs, the bearing structure needs at least a transverse connection element between the two supporting plates, to the detriment, however, of the number of components that make up the stair, and therefore its production costs, and also the complexity and times required for assembly.

Another disadvantage of known double-structure modular stairs is that, due to the mechanical conformation of their components, a possible L-shaped or U- shaped curve is achieved by means of one or more intermediate landings.

However, this solution entails an increase in the height of the tread or, possibly, an increase in the number of individual steps.

In both known solutions, the stairs made with the landing are inconvenient and difficult to climb, especially for elderly people or those with slight problems of movement.

Purpose of the present invention is therefore to achieve a double-structure modular stair which is simple and economical to make, is easy and quick to assemble, which has a reduced number of components, and which does not need landings to make curves or other changes in direction. The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

A double-structure modular stair according to the present invention comprises a plurality of modules assembled together so as to define the flight or flights of which the stair consists.

In accordance with the above purpose, each module comprises at least a step that defines the width of the stair, a first support element and a second support element associated laterally and on opposite sides to a lower surface of the relative step.

In a preferential embodiment, the two support elements are substantially specular, with respect to the median axis of the step.

The reciprocal attachment of the two support elements to the lateral parts of the lower surface of the step defines in itself a bearing structure, without needing other connection and/or reinforcement elements.

In this way, the stair according to the present invention is simplified, both with regard to production, and also with regard to assembly, with consequent reductions in the overall times and costs.

According to a characteristic feature of the present invention, both the first support element and the second support element are made starting from metal sheet, and, at least one of the two is substantially L-shaped rotated by 90° to the right. In particular, in the assembled condition, the L-shaped support element comprises a first segment, or tread segment, substantially horizontal, and a second segment, or riser segment, substantially vertical and extending downwards from a lower edge of the tread segment.

The L-shaped support element thus configured is also provided with at least a fin to attach it to the step, which is made in a single piece and co-planar to the relative support element along an upper edge of the tread segment.

With the present invention, therefore, we have the support element conformed with the riser segment extending downward, so that the upper edge of the tread segment is free, and any bending operations of the fin can be carried out with no risk of accidental direct or indirect deformations of the riser segment.

With the present invention, therefore, we have a simplification of the

operations to make the support elements, with a consequent reduction in the working discards, and in the production times and costs.

In a preferential form of embodiment, in which the stair according to the invention has a rectilinear development, both the first support element and the second support element are conformed as an L according to the characteristic of the invention, and have the respective fins bent in a specular manner, one with respect to the other.

According to another preferential form of embodiment of the invention, when the stair has at least one curve, the modules that define the curve each have an external L-shaped support element according to the above characteristics and also having more than one fin on its upper edge, and an internal element substantially consisting only of the riser segment and also having on its upper edge a fin to attach it to the step.

In this form of embodiment, thanks to the conformation of the support elements, instead of providing a single landing, various steps can be provided, two or three, each one having a substantially triangular shape. This solution allows to keep the height of the riser of the stair substantially constant and relatively small, simplifying assembly and reducing fatigue for the user.

According to another form of embodiment of the present invention, each support element, irrespective of its shape, comprises attachment means that allows to reciprocally attach the various adjacent modules in pre-determined reciprocal assembly positions.

According to a variant, the attachment means is of the multiple type, so as to allow a plurality of selective assembly positions of the stair according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some preferential forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein: - fig. 1 is a three-dimensional view from above of a double-structure stair according to the present invention;

- fig. 2 is an enlarged front view of one module of the stair in fig. 1;

- fig. 3 is a lateral view of a component of the stair in fig. 1, in a first working

step;

- fig. 4 is a three-dimensional view of the component in fig. 3, in a second working step;

- fig. 5 is a three-dimensional view from above of a second form of embodiment of a double-structure stair according to the present invention;

- fig. 6 is an enlarged detail of the stair in fig. 5.

DETAILED DESCRIPTION OF SOME PREFERENTIAL FORMS OF

EMBODIMENT

With reference to the attached drawings, a double-structure stair 10 according to the present invention consists of a plurality of modules 11, or 11a, each of which substantially consists of a step 12, or 12a, and two supporting plates 13, 15 or 16, constrained laterally to the lower surface of the relative step 12, or 12a, so that each module 11, or 1 Ia, autonomously defines a bearing structure.

In this case, the stair 10 comprises two rectilinear flights, each consisting of a relative plurality of rectilinear modules 11 with steps 12 of a substantially rectangular shape, and a 90° curve consisting of three triangular, modules 11a with steps 12a having a substantially triangular or quadrangular shape.

In particular, apart from the step 12, each rectilinear module 11 substantially consists of two supporting plates, respectively first 13 and second 15, shown on the left and right in fig. 2.

The two supporting plates 13 and 15 are substantially specular with respect to each other, and both are made by means of plasma cutting or laser cutting, starting from metal sheet.

Both the first supporting plate 13 and the second supporting plate 15 comprise a tread segment 17, disposed substantially horizontal during use, and a riser segment 19 extending downwards from a lower edge 17a of the tread segment 17.

Each supporting plate 13, 15 also comprises a respective attachment fin 20, which allows to attach the supporting plate 13, 15 to the lower surface of the relative step 12.

The attachment fin 20 is made in a single piece during the cutting step directly along an upper edge 17b of the tread segment 17 (fig. 3), and is then bent mechanically by about 90° onto one side or the other with respect to the tread

segment 17 (fig. 4), according to whether the first supporting plate 13 or the second supporting plate 15 is to be made.

The attachment fins 20 thus bent define the positioning plane of the step 12.

On the attachment fins 20, and also on the tread segment 17 and the riser segment 19, respective pairs of through holes 21 are made (figs. 1, 2, 3 and 4); which allow, in cooperation with screws and/or other ironwork elements of a known type and not shown here, to couple the various adjacent modules 11 with each other, in pre-defined reciprocal assembly positions and thus to form the stair 10. As can be seen in fig. 1, the original rectilinear module 11, that is, the one resting on the ground, has two supporting plates 13 and 15, having a riser segment 19 smaller than that of the supporting plates 13, 15 of the other modules 11 ; this is to allow a better support on the ground and to keep the height of the riser unchanged from the first to the last step of the stair 10. Each triangular module l la substantially consists, apart from the relative shaped step 12a, of a first supporting plate 13, substantially equivalent to those of the straight modules 11 and attached below on the external side of the step 12a, and a straight supporting plate 16 fixed below on the internal side of the step 12a.

In particular, the first and the last module l la of the curve have a first supporting plate 13 having a larger tread segment 17 and on the upper edge 17a of which two fins 20 are made.

The straight supporting plates 16 of each module l la substantially consist only of the tread segment 19 and comprise, on a relative upper edge 19a, a respective attachment fin 20, identical to those provided in the supporting plates 13 and 15. In these straight supporting plates 16 too, the attachment fin 20 is made in a single piece during the cutting step, directly along the upper edge 19a, and is then bent mechanically by about 90° onto one side or the other.

The attachment fins 20 of the straight supporting plates 16 thus bent define, in cooperation with the fins 20 of the first supporting plates 13, the positioning plane of the step 12.

In order to consolidate the reciprocal attachment of the triangular modules l la, and to ensure a greater support for the shaped steps 12a, the stair 10 according to the present invention also comprises an external connection plate

22, which allows to reciprocally connect the first supporting plates 13, an attachment L-bar 23, internal, and two attachment blades 25, also disposed on the internal part of the curve and able to reciprocally connect the straight plates 16.

As shown schematically in figs. 5 and 6, each supporting plate 13, 15 or 16 comprises various series of through holes 21, which allow different and selective reciprocal assembly positions between adjacent modules 11, 11a.

In this way, it is possible to obtain a great flexibility of assembly of the stair 10, possibly adapting selectively the heights of the riser and tread of the individual steps 12, 12a, according to possible structural errors of the walls and/or particular installation conditions of the stair itself.

Furthermore, since it can regulate as desired the riser and tread of the individual steps 12, 12a, this solution allows the possibility of making a single size type of modules 11, 11a, in order to make up stairs 10 of different sizes and therefore suitable for installation in premises that are different in size and with specific and personalized assembly requirements.

In this solution, in the triangular modules 11a, the first supporting plates 13 can be associated with extension elements 26, to allow a further adaptation to the specific assembly conditions of the stair 10.

It is clear, however, that modifications and/or additions of parts may be made to the stair 10 as described heretofore, without departing from the field and scope of the present invention.

For example, it comes within the field of the present invention to provide staples, pressure joints or other systems of reciprocal mechanical attachment of a known type instead of the through holes 21. It also comes within the field of the present invention to provide shaped eyelets instead of the series of through holes 21.

According to another variant, the straight supporting plate 16 also includes a tread segment.

According to another variant, the attachment L-bar 23 and the attachment blade 25 are integrated into the relative straight plates 16.

It is also clear that, although the present invention has been described with reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of double-structure stair, having the

characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.