In particular, the invention relates to a system for quick press-fit connection between structure long elements (rods) and the interconnection elements (connectors).

DESCRIPTION OF THE PRIOR ART Light load-bearing structures for construction of temporary or permanent scaffoldings, furniture elements, modular toys, shelves or others, used up to now mainly include structures equipped with two different types of connection modes between different elements.

A first type includes structures formed by main long elements, usually arranged vertical or horizontal, fastened by joints obtained by external fixing elements, or by particular conformations of the main elements.

Another type includes structures formed by multidirectional connectors and connecting rods, joined together by fastening screws, magnetic devices or interference fit.

All above described connection systems feature some drawbacks.

Typically, the most common drawback results from insufficient connection functionality and fastening rapidity, due to the use of the necessary fastening

elements, such as screws, bolts with nuts, washers and others.

Another drawback, featured mainly by interference fit fastening systems, derives from the fact that the force which must be applied to obtain a correct connection, is not constant, as it can depend on the tolerances of the elements to be coupled.

It can be difficult to separate the coupled elements afterwards, or the connection can be not stable enough.

A further drawback of the above described connection systems lies in the connection devices short life and in the not perfect repeatability of assembling and disassembling operations.

OBJECTS OF THE INVENTION The main object of the present invention is to propose a connection system for light load-bearing modular structures, including rods and multi-directional connectors, which outweighs the above described drawbacks.

Another object of the present invention is to propose a connection system which works without need of additional elements and which connects rods and multidirectional connectors in an immediate, stable and easily reversible way.

A further object of the present invention is to propose a connection system, which is cheap, simple to manufacture and very reliable.

SUMMARY OF THE INVENTION

The above mentioned objects are obtained, in accordance with the contents of the claims, by a new connection system, which includes connectors having a group of connector arms extending in predetermined directions.

Each connector arm is aimed at being introduced in a corresponding recess made in a rod to be connected.

A connector arm includes a body and a head. The head has a lateral aperture opening outwards.

The body features a longitudinal cavity, communicating with the lateral aperture, and a group of lateral through holes, communicating with the longitudinal cavity.

Corresponding gudgeons slide inside the through holes, between a non-working position and a working position.

When in the working position, the gudgeons protrude from the connector arm, so as to engage with the recess inner walls.

A shaped shaft, situated inside the cavity, is operated by the above described aperture, so as to bring the gudgeons from the non-working position to the working position and vice-versa.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristic features of the invention will be pointed out in the following detailed description with reference to the enclosed drawings, in which: -Figure 1 is a perspective view of the basic elements of a structure made in accordance with the present invention; -Figure 2 is a perspective view of a connector arm shown in Figure 1;

-Figure 3 is a perspective view of an inner element of the connector arm shown in Figure 2; -Figure 4 is plan view of the connector shown in Figure 1; -Figure 5 is a side view of the connector arm shown in Figure 3; -Figure 6 is a different side, partially sectional view of the connector arm shown in Figure 3; -Figure 7 is a front view of the connector arm shown in Figure 3; -Figure 8 is a section view taken along VIII-VIII in Figure 5; -Figure 9 is a section view taken along IX-IX in Figure 5.

DESCRIPTION OF PREFERRED EMBODIMENTS With reference to the above described figures and to one embodiment, reference numeral 1 indicates a multidirectional connector, which is a basic element of a modular load-bearing structure.

The structure, which can include a plurality of the above mentioned connectors 1, includes also a plurality of rods 2, each of which is aimed at being connected with at least two different multidirectional connectors 1, so as to form the modular structure.

The connector 1 is obtained by assembling a plurality of straight and substantially square section connector arms 10, oriented in predetermined directions.

In particular, according to the illustrated embodiment, the connector arms 10 are oriented along the orthogonal

axes.

In particular, the illustrated connector 1 is equipped with six connector arms 10, which extend on both sides of the connector 3 along three orthogonal axes.

It is obvious that both connector 1 and rod 2 can have different shapes, according to their actual use, and still remain within the protective scope of the present invention.

First of all, the number of arms 10 in a connector 1, as well as the arms orientation, can be different from the shown one, according to the structure conformation to be obtained and to the position that the connector 10 must assume inside the structure.

The rod 2 can have a different conformation, other than straight, as shown in Figure 1.

Moreover, the section of the connector arms 10 and of the relative recess 20 of the rods 2 can be different from a substantially square one, as shown in the above mentioned figures, e. g. they can be circular, polygonal, ovoid- like, helical or other.

The section of the rod 2 does not necessarily have to be identical as the section of the relative recess 20, e. g. the structure can have a rod 2 with circular section and recesses 20 having square section.

Each connector arm 10 (see also Figure 2) includes a body 11 and a head 12, situated at the end of the body 11.

The body 11 has a substantially cylindrical, longitudinal cavity 13, which extends along the whole length thereof.

The head 12 features a lateral aperture 14, opening outside and communicating with the longitudinal cavity 13.

The lateral aperture 14 is countersunk, so as to allow the introduction of a suitable tool, not shown, whose function will be explained later.

A plurality of through holes 15, communicating with the longitudinal cavity 13, are made in the lateral walls of the body 11 in predetermined positions.

According to the shown embodiment, the through holes 15 are made in the corners of the body 11.

A pair of the through holes 15, aligned with each other, are made on the opposite corners, near the head 12, while another pair of through holes 15, aligned with each other, are made on the remaining opposite corners near the opposite end of the body 11.

The holes section is rectangular, but it can be different, e. g. circular or polygonal.

The connection system includes also, for each connector arm 10, a shaft 30 (Figure 3), situated inside the longitudinal cavity 13, so that it can rotate thereinside.

The section of the shaft 30 is polygonal with rounded corners and its maximum dimension is slightly smaller than the dimension of the longitudinal cavity 13 of the body 11.

The length of the shaft 30 is such that it extends along the whole longitudinal cavity 13 and innermost portion of the lateral aperture 14 of the head 12 (Figures from 4 to 9).

A notch 33 of a predetermined depth is made at one end of the shaft 30.

According to another embodiment, the shaft 30 has a perimeter profile 32 including four cams having gradually

increasing radius.

The structure has one gudgeon 16 for each through hole 15 (Figures 2,8).

The shape of the gudgeon 16 allows it to be housed in the hole 15. The external end 16a of the gudgeon 16 is wedge- like shaped.

The gudgeon 16 features, made along its side, a step 17, which abuts against a corresponding stop 18 made in the through hole 15, so as to prevent the gudgeon 16 from leaving the hole.

The stop 18 is also aimed at blocking the gudgeon in the working position (Figure 8), in which the wedge-like end 16a of the gudgeon slightly protrudes from the body 11.

When the gudgeon is in the working position, the corners of the shaft 30, having the maximum diameter, touch the base of the gudgeons 16.

When the gudgeon is in the non-working position, not shown for sake of simplicity, but easily deduced, i. e. when the gudgeon is wholly contained in the body 11, the perimetral regions of the shaft 30 having minimum diameter touch the base of the gudgeons 16.

Finally, the connection system includes a closing element 19 (Figure 2), made of metal, gum or other suitable material, which tightly closes the longitudinal cavity 13.

Operation of the connection system will be described in the following, beginning from the condition, in which the rod 2 is not fastened to the connector 1 and the perimetral regions of the shaft 30 having the minimum diameter touch the base of the gudgeons 16, i. e. non- working position of the latter.

The notch 33 of the shaft 30 is aligned with the mouth of the lateral aperture 14.

In this situation, a connector arm 10 can be introduced into the recess 20 of a rod 2 (Figure 4), so that the end of the rod abuts against the head 14.

Then, a suitable tool, long and narrow, e. g. a common screw-driver, is introduced into the aperture 14, until its tip engages with the notch 33.

Then, the long and narrow tool rotates the shaft 30 by about 90°, so that the shaft corners having maximum diameter touches the base of the gudgeons 16.

Thus, the shaft moves the gudgeons toward their working position and brings their wedge-like ends 16a to press- touch the walls of the rod 2 recess 20.

Thus, a friction coupling between the connector 1 and the rod 2 is obtained, which is made particularly stable because of the number and positioning of the gudgeons 16.

Obviously, in order to disengage the rod 2 from the connector 1, it is enough to rotate the shaft 30 by about 90° in the opposite direction, so as to bring the gudgeons 16 back to their non-working position.

The main advantages of the present invention derive mainly from the use simplicity of the above described connection system.

Actually, no additional outer elements have to be assembled in order to fasten the rod 2 to the connector 1, as it is enough to act on elements which the system is already equipped with.

Moreover, the connection system according to the present invention, allows to obtain a particularly stable coupling, which is immediately reversible and

indefinitely repeatable.

Another advantage of the present invention derives from the fact that the elements necessary to obtain the structure connectors and rods are simple to manufacture.

It is understood that what above, has been described as a pure, not limitative example, therefore, possible variants of the invention remain within the protective scope of the present technical solution, as described above and claimed hereinafter.