Technical Field

For invention relates to a releasable structural bond in particular for establishing nodal points of lattice struc¬ tures including a negative receiving element provided with an aperture as well as an interconnecting positive piece for introducing thereto.

Background art

Several solutions have been known for interconnecting elements with .a rod character or to some anchoring body, optionally to elements of nodal point/s/ of lattice struc¬ ture. So, for example these kinds of solution are specified in the HU-PS 183 462 and 183 674, with which interconnec¬ tion of rod-elements in differential spatial directions, nodal connections used to be solved by means of spatially diviated bores and accessory nodal elements with clamping means. In addition to the generally known so-called bayonet locks for releasable connections without using accessory tools or auxiliary means a solution is known from the HU-PS 167 547, according to which forcelocking releasable connection between two structural elements - mainly with a road-like character - tolerating a pre-determined teπsional stress can be established by truπing by 90 the inter¬ connection element having been provided with elastic dis¬ tance pieces, e.g. rubber blocks on its mantle, to be in- troduced into a receiving element with rectangular cross- -section. This solution suffers from the disadvantage, in so far as establishing and releasing of the connection as well, require turns having been superimposed on the motion in direction of the rod, furtheron no self-locking connec- tion can be established either, it cannot be dimensioned mechanically with the proper reliability.

HU-PS 186 313 specifies an interconnecting structure, containing a connecting element having been provided with extensions made of some synthetic material whibh is able turn articulated on the mantle /simultaneously resulting in an increased dia ater of the mantle in course of turning/, which can be introduced into a sleeve¬ like receiving element with an internal cavity being accurate to dimension, with a relatively low expenditure on force. When it is intended to pull out i.e. to re¬ lease, said extensions intend to turn upon the effect of wall-friction, accordingly, some self-locking connection will be established between the connecting element and the receiving element. This connection, however, cannot be released by no means, and if, by destruction. The situation is the same, with pipe threads or any other discs for screw fixing. The aim of the invention is to provide an interconnection being free of the aforementioned disadvantages and de¬ ficiencies, which can be established resp. released without any auxiliary means and quickly, if possible, with a flick of the hand and low expenditure on force, at the same time considerable loadability is required, simultaneously assuring a self-locking so-called momentary bond between two rigid structural elements, which can be dimensioned for tension stress with the proper reliability in respect to strength.

Disclosure of Invention

The aim set can be achieved by means of a releasable structural bond, with which - in accordance with the invention - the aperture in the receiving element is a slit of the shape of an at least three-pointed star formed in the diaphragm-like sheet surface made of

an essentially elastic structural material, while the sur ace-ranges between the branches of slits form springy diaphragm-parts with a defined unloaded basic position; the interconnecting element in itself can be any rigid structural element, in particular forming the end-range of a tubular element or led therein movably, with cross- sectional profile of the shape of an at least three- -poiπted star in compliance with the split in the re¬ ceiving element, formed as a positive element with connecting fins to be introduced into the branches of the split; simultaneously the structural bond comprises an opening element led in a movable way in respect to the interconnecting element, arranged in the ranges between the connecting fins, provided with extensions bearing up agains the springy diaphragm parts of the receiving element by using an external force. To achieve a self-closing connection being reliable and suitable for taking up tensile forces, it seems to be preferable, if the split of the receiving element is formed with branches of split narrowing in a V-forma- tion towards the centre of the star and in the unloaded basic position of the diaphragm-parts the smallest width of the split branches is less, than the thickness of the connecting fins of the interconnecting element. According to a feature promoting increased and reliable self-locking and promoting oriented easy introduction of the interconnecting element it is considered as advantageous, if the split of the receiving element- is concave - viewed from the direction of introduction of the connecting element -, not to be spread in the plane, e.g. prior to cutting the split it is formed in the range of the deep-drawn resp. presseπd sheet surface. In particular, when using it a nodal element for latti¬ ce structures, for connecting structural elements of

rod-like character and having been provided - one by one - on both ends with interconnecting elements, in particular for the connection of tubular elements from pre-determi- ned spatial directions, we found it advantageous to form receiving elements, which have at least two splits. With these interconnecting elements receiving splits are arranged favourably on the mantle-surface of a hollow receiving element, having an essentially regular cavity, in particular tetrahedron /for four rods/, octahedron /for eight rods/, hexahedron /for six rods/ or spherical /for spherical nodal points/.

To facilitate ^' introduction it is considered as advanta¬ geous, if the interconnecting element is formed with bevelled connecting ribs converging in a common peak of tne interconnecting element. It becomes possible to con¬ nect rod-elements of given length between consistent, rigidly fixed receiving elements, without the necessity of displacing in direction of rod, by using the releas- able structural interconnections according to the in¬ vention, having an operating element, preferably a connecting element connected to a thrust ring, led in the end of a tubular element, kept in the basic still- stand position whithin the tubular element by means of a spring, while said operating element is arranged out¬ side the tubular element and introducing external force.

At last, an embodiment of the structural bond according to the invention is considered as advantageous, with. which there is an opening element arranged between the connecting ribs of the connecting elements, provided with extensions, led with a degree of freedom of dis¬ placement simultaneously in respect to the connecting element and the structural element of rod-character as well, in particular in respect to a tubular element,

while said opening element is kept in its basic still- stand pύbition within the tabular element by spring force and via the radial ribs led out on the mantle grooves of the tubular element it is connected to a force-introducing carrier ring arranged outside the tubular element.

Without aiming at completeness, releasable structural bonds according to the invention can be most advanta¬ geously used for connecting lattice structures, per¬ manent and provisional frames, formation of construc¬ tions with consoles, rod junctions, connection of con¬ structive and logical toys and several other purposes,.

Brief Description of Drawing

Essential features of the structural bond according to the invention will be detailed by means of a preferred embodiment, with reference to the accompanying drawings in which: Fig. 1 is a schematic view of the receiving element and interconnecting element of the releasable structural bond according to the invention;

Fig illustrates another possible embodiment of the invention, showing a perspectivic view of the receiving element for establishing the nodal point of a spatial lattice structure; Fig. 3 illustrates a connecting resp. opening element of the releasable structural bond according to the invention, as well as a perspectivic broken sectional view showing the possible arrangement in the end .of some tubular element, while Fig. 4 to 7 show the mode of operation of the struc¬ tural bond according to the invention, show- ing schematically the characteristic phases

of connecting and releasing, respectively.

Best Mode of Carrying out the Invention

The embodiment according to the invention, as shown in Fig. 1 illustrates schematically the receiving element 1 and the connecting element 2 of the structural bond, wherein the receiving element 1 is made of some elastic structural material, seen from above according to the drawing it has a concave shape, not developable, that means it cannot be spread in plane, i.e. a sheet sur¬ face approaching the mantle-sur ace of a pyramid with a square base, wherein, in said sheet-surface a slit 10 is cut, having the shape of a four-pointed star. As it becomes obvious from the Fig. 1, the split 10 is formed with branches 101, 102, 103 and 104 narrowing towards the centre coinciding with the vertex of the pyramid, whereas the essentially triangular surface ranges between the branches 102, 101, 103, 104 are defined as springy diaphragm-parts 105, 106, 107 and 108 with an unloaded basic positon. The connecting element 2 may form the end-range of some structural element with a rod-like character /not illustrated here/ and has a profile being in compliance with the split 10 of the receiving element 1, i.e. with the shape of a four-pointed star; the receiving element 1 has connecting ribs 21, 22, 23 and 24 which can be introduced into the branches 101, 102, 103, 104 of the split, ends of said ribs are be¬ velled so, as to converge in a common vertex for faci¬ litating introduction.

Wall-thickness of the connecting ribs 21, 22, 23 and 24 as well as dimension of the /V-shaped/ openings of the branches 101, 102, 103 and 104 of the split have

been selected so, that the smallest width of the aperture should be less, than the thickness of the rib, while width of the aperture is increasing start- ing from the centre, reaches the thickness of the rib, the more, it even exceeds it to a trifle extent. In case, is the connecting element 2 is displaced, as shown by the arrow in Fig. 1, with a slight ex¬ penditure on force we may lead the connecting element into the split 10 of the receiving element 1, between the branches 101, 102, 103 and 104 diaphragma-parts

105, 106, 107 and 108 will be elastically deformed in comparison to their unloaded basic state and exert a defined clamping force onto the connecting ribs 21, 22, 23 and 24 of the connecting element 2. Additionally, the clamping connection thus established shows a self-locking character, since the connecting element is of opposite sense, as a consequence, if it is dis¬ placed in sense of pulling, clamping force will in- crease. Release of clamping connection becomes possib¬ le only, if a co pressive force is exerted, deforming further elastically the springy membrane-parts 105,

106, 107 and 108, as well as influencing the size of the aperture of branches 101, 102, 103 and 104 of split in an increasing sense and as long as the connecting element 2 is removed by pulling from the receiving element. The third element of the releas¬ able structural bond with a well defined function,, the opening element, serves just for this purpose, this will be discussed later.

It becomes obvious that, if the receiving -element 1 and connecting element 2 are arranged e.g. on the proper end of a structural element each with a rod- -like character, by the aid thereof, by a flick of

the hand, with a slight expenditure on force /as re¬ sistance occuring in course of introduction may be rather low/, a bond resp. connection can be established between said structural elements with a rod-like character, being well resistant to compressive and tensile stresses acting in the direction of the rod. Shape of cross-section is quite neutral from the point 0 of view of connection, accordingly cross-section of the rod may be a circular profile or any other one, so e.g. rectangular or polygonal. For establishing nodal con¬ nections of planar, or even spatial lattic structure receiving elements 1 may be formed, with which the l ^~ splits 10 receiving the connecting element 2 having been arranged at the end of the lattice rods form essentially a regular body, so - in a way as shown in Fig. 2 - on the mantle surface of a hollow cube, most advantageously, when viewed from outwards, in the 20 surfacial ranges with concave indentations, e.g. in case of a cube, they are formed in a mutual perpendi¬ cular direction. It is easy to see that the receiving element may have a spherical surface or that of a calotte, so it needs not be confined necessarily by 2 planar faces. Split/s/ 10 must have at least three points to achieve satisfactory holding in direction of the rod by the aid of the connection. It goes without saying that splits 10 with four points, or optionally with a plurality of points can be formed, while the 30 connecting elements with the connecting ribs are arranged in compliance therewith. As already mentioned before, in order to be able to establish a releasable structural bond, a functionally proper opening element is indispensable. Additionally, in practice it becomes 35* often necessary that between two consistently installed

receiving elements 1 - that means arranged in mutually determined distance - /without the necessity and possi- bility of the displacement in direction of rod/ a ^* structural element with a proper lenght - based on the principle of the invention - with a rod-like character could be inserted. Fig. 3 gives an example for solving said task, while Fig. 4 to 7 show the operation of the releasable structural bond in accor¬ dance with the invention. Fig. 3 illustrates structural solution - serving here merely as an example - of the connecting element 2 and the opening element 3, shown in a partial sectional broken view. From Fig. 3 it becomes obvious that at the end of a tubular element 4 /of optional length and with a circular cross-section in the given case/ there is a connecting element 2 led so, as to be displaced in direction of the rod, in an arrangement of a four- -pointed star, provided with the connecting ribs 21, 22 (in Fig. 3 but two are illustrated). The connect¬ ing element 2 is kept in its basic position in the tubular element 4 - as to be seen in Fig. 3 - by means of a slightly pre-stressed compressive spring 27, bearing up against the annular lower supporting shoulder 44 having been built-in consistently in the tubular element 4, partly on the radial ribs 25 led in the mantle-grooves 41 of the tubular element 4. Outer ends of the ribs 25 are coupled to a circular pressure ring 26 fitting loosely to the outer mantle-surface of the tubular element 4. By displacing the pressure ring 26 downwards /in sense of Fig. 3/ and by simul¬ taneous compression of the compressive spring 27 the connecting element 2 can be pushed out from the tubu-

lar element 4. After having relieved the pressure ring 26, the compressive spring 27 returns the connecting element 2 in its basic position, as to be seen in Fig. 3.

With a similar solution the four-pointed opening ele¬ ment 3 having been provided with the extensions 30 between the connecting elements 21, 22 (and further two, not illustrated here) is led with a degree of freedom of displacement in the tubular element 4. Basic still-stand position of the opening element 3 in the tubular element 4 will be maintained by the compressive spring 33, being slightly pre-stressed and which is bearing up partly against the annular supporting shoulder 43 having been fixed in the tubu¬ lar element 3, partly against the ribs 31 of the open¬ ing element 3 led in the mantle-grooves 42 of the tubular element 4. Basic position within the tubular element 4 is defined by the flange 45. Similarly to the pressure ring 26 of the connecting element 2, ends of the ribs 31 are coupled to the carrier ring 32 fitted loosely to the outer mantlesurface of the tubular element 4. By displacing the carrier ring 32 in direction of the end of the tubular element the opening element 3 can be pushed out from the tubular element 4, meanwhile the compressive spring will be compressed. Now, if we release the carrier ring 32, the compressive spring 33 returns the opening element 3 into the basic still-stand position, as to be seen in Fig. 3-

The structural solution can be essentially characteri¬ zed in that the connecting element 2 and the opening element 3 can be pushed out separately, however, simultaneously too, from the inner space of the

tubular element 4, in an unloaded state /without any external force exterted thereon/ both will return into the basic stillstand position, in this position they do not reach beyond the end of the tubular element 4, thus the length is not increased.

Mode of operation of the embodiment of the releasable structural bond - as illustrated in Fig. 3 - will be detailed by referring to Figs. ^' 4 to 7.

For the sake of better understanding in Figs. 4 to 7 merely those structural elements are provided with re¬ ference numbers, which are important from the point of view of specifying mode of operation. Fig. 4 illustrates the releasable structural bond in its basic stillstand position, both the connecting element 2 and the opening element 3 are lying in the inside of the tubular element 4. Tubular element 4 is in a positioned state prepared for being connected to the receiving element 1 of the tubular element. In Fig. 5 the position is illustrated, in which the connecting element 2 is led into the receiving element 1 by means of the force exerted on the pressure ring 26 /indicated with an arrow in Fig. 5/ with the simul- taneous compression of the cor.pressive spring 27. By virtue of the aforementioned self-locking character, the connecting element 2 will be coupled permanently to the receiving element (that means even after having released the pressure ring 2 ", a stable, mechanically loadable connection is established, establishment does not require displacement of the tubular element 4. As it becomes obvious from Fig. 6, for releasing the connection resp. bond the carrier ring 32 is dis¬ placed in direction of the receiving element 1 - as indicated with the ^" arrow - up n the effect of an external force. In such a anr.er the extensions 30 of

the opening element 3 deform elastically the diaphragm- -parts of the receiving element 1, which provide for receipt and self-locking, by widening the branches of the split, as a consequence, selflocking connection with the connecting ribs 21, 22 (and with the other two, not illustrated here) will be relieved, and as it is indicated by the dotted arrow in Fig. 7, connect¬ ing element 2 will be returned to the basic stillstand position /meanwhile continuous external force is exer¬ ted on the carrier ring 32/. Thereafter we release the carrier ring 32 which returns to its basic stillstand position /upon the effect of the compressive spring 32/, bond resp. connection does not couple anymore, re¬ leased starting state according to Fig. 4 appears. Unambiguously the releasable structural bond can be established with different constructional solutions differing from the embodiment discribed above, how¬ ever, being analogous in respect to principal function. The main advantage of the releasable structural bond according to the invention lies in that neither con¬ nection, nor releasing require the use of separate accessory elements or auxiliary tools. The bond thus formed is well suitable for taking up force-effect acting in direction of rods, the bond is stable and can be dimensioned in respect to strength. It can be excellently used for nodal points of lattice struc- tures, in particular for lattice structures formed by trigonometric plotting, wherein in the nodal points no bending stresses arise. A further, most important advantage lies in, that establishing of connection

/that means, introduction of the connecting element into the receiving element/ occurs with a slight expenditure of forces only, without rotating the element with a rod-like character, in case of a

satisfactory formation of the construction displace¬ ment cf the rod in direction of the rod becomes super¬ fluous. Such a structural bond can be advantageously used for nodal points of spatial lattice structures, while time requirement for assembly and disassembly is utmost low. By forming and using connecting elements with several points spatial elements with different geometry can be interconnected, in the same way. The structural bond according to the invention is well suitable for coupling different spatial logical toys.