GB2300240A - Constructional system - Google Patents

Abstract

A constructional system comprises a framework made up of struts (3) and nodal connectors (1), the end of each strut (3) being formed with a universal joint comprising a ball (5) received in a socket (6), which as it is screwed into a tapering recess (11) in the connector (1), clamps the position of the universal joint. The struts (3) may be telescopically adjustable in length, and clamped by means of a wedge ring (not shown) within a locking collar. The struts (3) may be compressed or extended by means of springs or pneumatics. The system can be used as a toy or for modelling, or for constructing exhibition stands or temporary buildings.

Description

IMPROVEMENTS RELATING TO CONSTRUCTION 8Y8TEMS Field of the Invention: The present invention concerns improvements relating to construction systems and has particular, though not exclusive application to construction toys and modelling systems.

Backaround of the Invention: Construction toys and modelling systems are long time favourites with children and provide both recreational and educational opportunities. Firm favourite systems that have endured the test of time are the well known MECCANO and LEGOw systems, and the LEGO TECHNIKz system has added technological capabilities to the original LEGOw interlocking brick system.

A new construction toy system known as K'NEXw is gaining in popularity. The K'NEXw system is described in US-A-5 061 219, US-A-5 137 486, US-A- 5 199 919, US-A-5 238 438, US-A-5 346 420, US-A-5 350 331, US-A-5 358 514 and in corresponding patents and patent applications in other countries. The K'NEXz system comprises connector elements of different shapes which are provided with one or more gripping sockets, and rod-like struts of a variety of different lengths which have end portions configured to be received in the gripping sockets. The gripping sockets are defined by pairs of gripping arms formed of deflectable plastics material. Outer portions of the gripping arms have concave grooves for lateral, snapin assembly of struts having complementary cylinder connector portions near their ends.The gripping arms also have locking projections for interlocking with annular recesses near the ends of the struts, nearer to the ends than the cylinder connector portions. End flanges provided on the struts are received in a cavity at the closed end of the gripping socket.

When the end of a rod-like strut is received in a gripping socket the strut is held firm in the socket and, whilst it can be rotated in the socket about its axis, the strut otherwise has no freedom of movement.

The K'NEXz system includes connector elements having gripping sockets facing in different directions all in the same plane (see Fig.1 of US-A-5 061 219) and further includes connector elements which can be coupled together to provide a multi-directional socket facility in two perpendicular planes (see Fig.l of US A-5 317 486). By this means, the K'NEXw system provides for strut connections to a connector node from a plurality of predetermined directions in each of two perpendicular planes, but otherwise the range of directions from which a strut can be connected to a connector node is severely limited.

Obiects and Summarv of the Invention: It is a principal object of the present invention to overcome or at least substantially reduce the abovementioned problem of the K'NEXz system.

According to the present invention, in one of its aspects, the abovementioned object is achieved by a constructional system in which gripping sockets and the co-operating ends of rod-like struts engage with each other by means of universal joints which provide for a substantial degree of freedom of movement of the struts relative to the gripping sockets, and locking means are provided for locking the universal joints in any desired relative position of the gripping sockets and the struts.

In a preferred embodiment of the abovementioned aspect of the invention the universal joints are balland-socket joints. The strut ends are formed with a ball which is received within a complementary recess formed in a generally frusto-conical locking member.

The external surface of the locking member is formed with a screw thread and is adapted to be received within a complementarily shaped gripping socket provided with a complementary screw thread. The locking member is formed to be compressible, for example by having a slit cut in its side wall or by being formed of a compressible material, so that with the locking member engaged in the socket a small degree of turning movement of the locking member is such as to secure the locking member in the socket and at the same time tighten the locking member about the ball at the end of the strut so as to fix the strut in a set angular orientation relative to the socket.

The gripping sockets can be formed in or on connector elements of different shapes and configurations. A generally hub-shaped connector element could have gripping sockets arranged around its periphery, similarly to the arrangement of Fig.l of US-A-5 238 438 aforementioned. Whereas the corresponding K'NEXz element provides only for connection of struts to such an element with the struts extending radially and all in the same plane, the arrangement of the present invention provides much greater directional freedom in regard to strut orientation by virtue of the universal joint connecting the strut to the connector element.Even greater possibilities as regards the directions in which struts can connect to the connector element can be achieved by forming the connector element as a three-dimensional structure (as compared to the essentially two-dimensional structure of the K'NEXz element shown in Fig.l of US-A-5 238 438) and providing gripping sockets in or on the connector element which extend or face in a plurality of different directions which are not all coplanar. Such a three-dimensional connector element might be generally spherical or hemispherical for example.

As with the connector elements of the K'NEXw system which provide for the struts to be engaged transversely with the gripping sockets in addition to being endwise or axially engageable therewith, in the system of the present invention provision may likewise be made for the struts to engage generally transversely with the connector elements. In a generally two-dimensional connector element in accordance with the present invention, for example, in addition to the gripping sockets which are adapted to connect with the strut ends via universal joint means there might be provided additional gripping sockets adapted for sideways or transverse engagement with the struts and/or apertures adapted to receive the struts to the same or similar effect.

In accordance with another aspect of the present invention adjustable length struts are provided so as further to enhance the versatility of the system.

Preferably the struts are telescopic and incorporate locking means enabling them to be locked at an adjusted length. In a preferred embodiment which will be described in detail hereinafter, the outer one of two telescopic strut elements carries at its inner end (the end remote from the end adapted for engagement with the gripping sockets) a locking ring which is screw-threadedly engaged with the inner end of the respective strut element and is arranged so that when it is tightened the two telescopic strut elements are locked together. This might be achieved simply by provision of a wedge or ramp formation on one of the parts which, when the locking ring is tightened, serves to clamp on the inner strut element. For example, the locking ring might be arranged to act on the end of the inner end of the outer strut element, which might be inherently resilient or might be split so as to impart resilience. Alternatively a wedge ring might be incorporated into the locking ring, somewhat similarly to the sealing ring or so-called "olive" that is commonly provided in compression type plumbing fittings.

In addition to having adjustable length struts as aforesaid, it is considered that for some applications it would be advantageous if the struts were capable of elastic compression and/or extension about a set length. One way of achieving this would be to utilize compression and/or tension springs with a telescopic strut construction, but this is not preferred. More preferable, in accordance with the present invention, is the use of pneumatics to provide the necessary elasticity. Just as the compression of air in a bicycle pump provides a spring force which must be overcome in order to inflate the tyre, so a compression spring force can be developed in a telescopic strut by pneumatic means. Similarly, a tension spring force can be developed by having an expanding telescopic strut work against a vacuum pressure.

According to yet another aspect of the present invention therefore adjustable length struts are provided which can be set to a desired length and then can be adjusted further, in compression and/or extension, against the action of a spring force, the spring force preferably, though not essentially, being achieved by pneumatic means. In a preferred embodiment of this aspect of the invention, a pneumatic component is provided which is adapted for use with telescopically adjustable struts and comprises inner and outer cylindrical parts which are received one within the other and can move axially in relation to one another.The inner cylindrical part is adapted to be secured to the end of the outer telescopic element of the strut, and the outer cylindrical part is adapted to be secured to the inner telescopic element of the strut, for example by means of a locking means substantially as aforedescribed for locking the adjustable struts to a set length, once the strut length has been adjusted to a set length. Between them, the inner and outer cylindrical parts define at least one chamber which is delimited by seals which permit the axial extent of the chamber to vary, as the inner and outer parts are moved relatively, thereby compressing or expanding the air in the chamber whilst maintaining the integrity of the seals.By virtue of such an arrangement, the nominally adjusted strut length is variable in compression and/or extension against the action of the air in the chamber which has correspondingly to be compressed and/or expanded. Such a pneumatic component could also be utilized with struts of nominally fixed length, namely without any length adjusting means.

The above and further aspects and features of the present invention are set forth with particularity in the appended claims and, together with the advantages thereof, will best be appreciated from consideration of the following detailed description given with reference to the accompanying drawings.

Description of the Drawings: Figures 1A and 1B are a schematic showing of an exemplary generally spherical connector element embodying the present invention; Figures 2A and 2B are schematic showings of an exemplary ball-and-socket type universal joint arrangement constituted by a ball formed on the end of a strut, and a locking member configured internally to receive the strut ball end and externally to be received in a gripping socket formed in a connector element such as that shown in Figures 1A and lB; Figure 3 is a cross-sectional view showing how the ball-and-socket universal joint arrangement of Figures 2A and 2B interfaces with the gripping sockets of a connector element such as that shown in Figures 1A and lB; Figure 4 shows a cross-sectional view of an exemplary arrangement whereby strut lengths can be adjusted and set;; Figures 5A and 5B are perspective views of a wedge ring that is used in the arrangement of Figure 4, Figure 5A showing the wedge ring in its free state and Figure 5B showing it when compressed in use about an inner element of a telescopic strut; Figure 6 is a perspective view of a locking collar that is used in the arrangement of Figure 4; and Figures 7A and 7B show, respectively, a crosssectional view of an exemplary pneumatic component whereby telescopic struts are elastically compressible or extensible, and a plan view of a port seal that is used in the pneumatic component of Figure 7A.

Detailed Descrintion of the Embodiments: Referring first to Figures 1A and 1B of the accompanying drawings, shown therein is an exemplary connector element which can be used as a universal node in a constructional system, for example a constructional toy or modelling system, in accordance with the present invention. The connector element is generally spherical with planar sites 2 provided for the attachment to the element 1 of ball-and-socket type universal joint arrangements, as shown in Figures 2A and 2B, generally in the manner shown in Figure 3.

It is understood that not all of the fixing positions 2 are shown in Figures 1A and 1B and that screwthreaded details of the fixing positions also are not shown. The connector element 1 is based upon a socalled Fullerine having a surface composed of hexagonal and pentagonal facets, 20 hexagonal and 12 pentagonal, and each facet could be provided with an attachment site 2 so that a maximum of 32 struts could be attached. Such a connector element could have utility even if the attachment sites 2 were formed so that a strut could be fixed thereto only in a direction perpendicular to the respective facet, but the universal joint arrangement that is preferred in accordance with the present invention for fixing the struts to the connector elements vastly enhances the application possibilities.

Figures 2A and 2B show the presently preferred ball-and-socket type universal joint arrangement which the present invention proposes for coupling struts to the connector element 1. Figure 2A shows the end of a strut 3 being formed with a frusto-conical taper 4 and a spherical ball 5 (see also Figure 3). A locking member 6, which is shown in its free state in Figure 2B, is generally frusto-conical with an internal recess 7, a portion 8 of which is shaped complementarily to the ball 5 at the end of the strut (see Figure 3). The external frusto-conical surface of the locking member 6 is screw-threaded at 9 and a mating, complementary screw-thread 10 is provided as shown in Figure 3 within a frusto-conical recess 11 that is provided at each of the fixing sites 2 that are provided on the connector element 1.

As shown, the locking member 6 has a split 12 through its wall thickness which enables it to be snapped over the ball 5 on the end of the strut and retained by the ball ready for use. Alternatively, the locking member 6 could be made of a less rigid plastics material than the strut, thereby enabling the ball 5 to be forced into its accommodating recess 8.

In either case, as the locking member 6 is screwed into one of the fixing sites 2 on the connector element 1, so it is tightened about the ball 5 as it moves towards the vertex of the conical bore until no further compression is possible. Because the bore of the recess 11 at the respective fixing site 2 is conical, the locking member 6 can be placed deeply into it so that little further rotation is required to screw it fully home. For example, about half a turn of the locking member 6 might suffice to retain the locking member 6 in the fixing site 2 but with the strut end ball 5 held loosely such that it can readily be pivoted, and a further quarter of a turn would then lock the ball tight. The screw threads that are formed on the locking member 6 and within the fixing sites 2 can be formed with a bias to maximise the ability to retain a strut under tension, as is shown in Figure 3 for example, and the conical shapes of the locking member 6 and the recesses 11 readily sustain compression.

The locking member 6 is formed with a generally castellated crown 13 which provides a finger grip to enable the locking member to be easily screwed into one of the fixing sites 2 on the connector element 1 and also provides minimum restriction to articulation of the ball-and-socket joint. This is further facilitated by the wide angled conical inlet portion 14 of the internal recess 7 of the locking member.

The shape of the crown 13 as shown in Figures 2A and 2B is exemplary only and instead of, or additional to, the castellations, the crown of the locking member could be textured to provide a finger grip and/or could be shaped to accept a locking spanner.

Alternatively, or additionally, the ball-and-socket joint constituted by the strut end ball 5 and the accommodating complementary recess portion 8 could be provided with a stud and mating groove to constrain the rotation of the ball in the plane of the socket so that rotation of the strut about its axis will cause the socket to be rotated, namely will cause the locking member 6 to be rotated. If the stud is provided on the ball then the groove should run perpendicular to the plane of the socket, and if the stud is on the equator of the socket then the groove should run longitudinally along the ball.

Before moving on to consider a different aspect of the present invention, namely the adjustability of the strut lengths, it is to be appreciated that curved lines and surfaces in Figures 1A and 1B, and more particularly in Figures 2A and 2B, have been shown not as smoothly curved, but rather as a series of straight lines or planar surfaces. The same is the case for Figures 5A and 5B and Figure 6. This results from limitations of the computer program used to prepare the drawings, and the correct situation will readily be understood by the skilled reader.

Referring now to Figure 4, and to Figures 5A, 5B and 6, there will now be described an exemplary arrangement in accordance with the present invention whereby the strut lengths may be adjusted and locked at a set length. In the arrangement shown, each strut comprises an outer strut member 15 and an inner strut member 16, the two members being arranged to telescope with the inner strut member 16 fitting into a bore 17 of the outer strut member 15. Figure 4 shows the axially inner ends of the two strut members 15, 16 and it will be understood that at their axially outer ends the members 15, 16 are each formed with a conical part 4 and a ball 5 as hereinbefore described with reference to Figure 2A.A locking ring or collar 18 is screw-threadedly attached to the inner end of the strut member 15 and a wedge ring 19 is interposed, within the locking collar 18, between an inclined wedging surface 20 provided on the collar 18 and an oppositely-inclined wedging surface 21 provided at the end of the strut member 15. The wedge ring 19 is split at 22 as shown in Figure 5A, and the action of screwing the locking collar 18 onto the end of the outer strut member 15 serves to close the wedge ring 19 around the inner strut member 16 and lock the inner strut member 16 in adjusted position within the outer strut member 15.As shown, the outer surface of the inner strut member 16 is textured to provide the wedge ring 19 with a good grip, the texturing in the arrangement shown comprising a fine lead low profile screw-thread, and a complementary thread or other texturing is preferably provided on the gripping surface of the wedge ring 19.

With the arrangement shown in Figure 4, as the locking collar 18 is tightened onto the end of the outer strut member 15 so the wedge ring 19 closes up and fits its conforming screw thread into that provided on the end of the inner strut member 16. As the collar 18 is completely tightened, the wedge ring 19 grips the inner strut member 16 firmly and is itself held firmly between the locking collar 18 and the inclined end face of the outer strut member 15.

By virtue of the wedging surfaces provided within the locking collar 18, on the end of the outer strut member 15 and on the wedge ring 19, it is ensured that any compression or tension applied to the locked strut can only serve to force the wedging ring 19 even tighter against the inner strut member 16 thereby increasing the locking force. The locking collar 18 need only be unscrewed slightly, possibly as little as half a turn, and the wedge ring 19 will be enabled to expand its diameter by virtue of its resilience and so release the inner strut member 16.Coarse adjustment of the strut length is achieved simply by slackening the locking collar 18 and either pushing the inner strut member 16 into the outer strut member 15 or pulling it out, and fine adjustment can be achieved by partially tightening the locking collar 18 so as to engage the screw threads of the wedge ring 19 with those on the inner strut member 16, and then screwing the inner strut member 16 into or out of the outer strut member 15. If this latter facility is to be relied upon, then the wedging ring 19 may be shaped externally so that it keys into the locking collar 18 in a manner such that it cannot rotate within the locking collar.

The wedging ring 19 formed of a resilient rigid plastics material could alternatively be formed of a softer, deformable material, such as an elastomeric material for example. The described arrangement is preferred, however, inter alia on account of its fine adjustment facility.

Adjustable struts as described in the foregoing way advantageously be made available in a series of length options such that the largest extension of the smaller strut is always greater than the smallest length of the next largest strut size. By this means all possible strut lengths can be achieved ranging from the minimum adjusted length of the shortest strut to the maximum length of the longest.

Reference should now be made to Figures 7A and 7B of the accompanying drawings which show a pneumatic means providing for extension and/or compression of an adjusted strut length against the action of a spring force. Such a facility may be useful in some modelling applications for example, and also enables the distribution of forces throughout a modelled structure subjected to loading to be determined. As shown in Figure 7A, a telescopically adjustable strut comprises an outer strut member 15 and an inner strut member 16 as aforedescribed with reference to Figure 4, and a pneumatic device 25 as aforementioned is operatively associated with the two strut members 15, 16.The device 25 comprises an inner cylindrical bore component 26 dimensioned to fit closely around the outer strut member 15 and having an internal screw thread 27 at its inner end (namely its lower end as viewed in Figure 7A) which is adapted to be threadedly engaged with the screw thread that is provided externally of the inner (lower) end of strut member 15, and an outer cylindrical bore component 28 which is coupled to an extension 29 which in turn is coupled to a clamping or locking arrangement 30 which is substantially as hereinbefore described with reference to Figure 4 and comprises a clamping collar 31 adapted to screw threadedly engage a reduced diameter end portion of the extension 29 and a wedge ring 32.

Affixed to the lower end of inner cylindrical bore component 26 is a ring element 33 which, on its radially inner side, serves as a stop to limit the travel of the end of the outer strut member 15 into the component 26 when the two are being screwed together and, on its radially outer side, serves as a key to engage with axial slots 34 that are provided in the inner cylindrical surface of extension piece 29, such engagement ensuring that the inner bore component 26 cannot rotate with respect to the extension piece 29 so that the component 26, which is relatively inaccessible, can be screwed onto the end of the outer strut member 15 by rotation of the extension piece 29 and its attached outer bore component 28.

At the upper end of the outer bore component 28 there is provided a radial seal 35 which is directed inwardly into sealing contact with the smooth external surface of the inner bore component 26. A similar radial seal 36 is provided at the lower end of the component 28 where it is affixed to the extension piece 29. The two radial seals 35 and 36 define between them, and between the outer cylindrical surface of the inner bore component 26 and the inner cylindrical surface of the outer bore component 28, a pneumatic chamber 37 which is divided into two parts 37' and 37'' by a further radial seal 38 that is mounted on a central flange 39 provided on the inner bore component 26.The inner bore component 26 is furthermore formed with an axial slot 40 in its inner surface which extends from its outer (upper) end to just past the location of the flange 39, and an elastomeric pad seal 41 which is shown in plan view in Figure 7B is received at the closed end of this slot 40. The wall of the inner bore component 26 is pierced on either side of the flange 39 so as to define ports 42 and 43 which provide communication to the chamber parts 37' and 37'' respectively, and the pad seal 41 seals these ports with respect to the surface of the outer strut member 15, except as described hereinafter in connection with the through hole 44 and the depression 45 that are provided in the strut member 15.

To assemble the pneumatic device 25, the three radial seals 35, 36 and 38 and the pad seal 41 are first located and fixed in position, for example by use of a suitable adhesive. The ring component 33 is then firmly attached to the inner (bottom) end of the inner bore component 26 and, taking care to align the key parts of the ring component 33 with the slots 34, the inner bore component 26 can then be carefully inserted into the extension part 29. The outer bore component 28 can then be assembled and secured at its lower end to the extension part 29. A flexible pleated boot 46 may then be secured between the inner bore component 26 and the outer bore component 28 to protect the seals against ingress of dust and dirt.

With the device 25 thus assembled, it can be screwed onto the lower end of the outer strut component 15, and the clamping arrangement 30 can be clamped to the surface of an inner telescopic strut member 16 as hereinbefore described with reference to Figure 4, only in the present arrangement the inner strut member 16 is clamped to the extension piece 29 of the device 25 and not to the outer strut member 15.

While the device 25, assembled as described, is not attached to the outer strut member 15, the double acting piston constituted by the flange 39 acting within the chamber 37 can be displaced in either direction without affecting the air pressure in either of chambers 37', 37'' because the ports 42, 43 will be open. However, when the device is slid onto the end of the outer strut member 15, the surface of the member 15 acts against the pad seal 41 surrounding the ports 42, 43 and effectively closes them off, both individually from each other and as a pair from the outside world. Before the device becomes tight on the outer strut end thread, the port seals 41 pass over a moulded-in depression 45 in the outer strut 15. While in this location, air can pass from one side of the chamber 37 to the other, without being able to escape completely.Once the device 25 is further tightened (rotated away from the depression), the seals 41 will prevent air moving between the two compartments 37' and 37'' of the chamber 37. If the device is arranged with the flange 39 positioned centrally along the cylinder bore, then the device will act equally in compression and tension. If the device is extended to its maximum length before the air is trapped, namely before it is assembled to strut element 15, it will act in compression over its whole length of travel.

If the device is compressed to its shortest length before the air is trapped then it will act in tension over its whole length of travel.

Because the cylinder is double acting, there will always be air in compression where it can resist displacement forces on an exponential force scale. If it relied on vacuum to pull the cylinder closed, the force would be limited by atmospheric pressure, which over an area of 1 sq.cm would only provide a force of approximately 1keg. Before reaching the radial position of the depression 45, one side of the port seal 41 passes over the hole 44 in the outer strut member 15. This feature allows the unit to be pressurised, thereby stiffening the suspension response.In order to increase the amount of air (pressure) in the two chambers 37' and 37'' the following procedure is followed: - First with both ports 42 and 43 located over the depression 45, extend the device 25 so as to cause all of the air to flow into the chamber 37''; - Move the ports so that the port 42 is over the hole 44 by unscrewing the device slightly around the strut 15.Then compress the chamber 37'' by closing the two parts of the device together and at the same time cause new air to flow into the chamber 37' though hole 44 and port 42; - Move the ports 42 and 43 back to the depression 45 and either repeat the process to increase the pressure still further, or - Establish the required mode (variable from all tension to all compression) by setting the relative sizes of the chambers 37' and 37'' about the divider 39 and then lock by screwing the device tight on the strut member 15.

Each cycle through the abovedescribed loop delivers diminishing returns because the amount of new air sucked in by enlargement of chamber 37' is limited by inability to compress the increasing volume in chamber 37''. If the air is compressed to 8 Bar (about 8kgf on a 1 cm square) by user applied force, after the first cycle the pressure in both cylinders will be 1.8 Bar, after the second cycle 2.44 Bar, the third cycle 2.95 Bar etc. up to a theoretical maximum for a perfect system after infinite cycles of 8 Bar in the whole cylinder. This cannot be reached because there will always be some air left in the port channels and other seal spaces (and infinity tries ones patience). Practical pressures that can be achieved manually range up to about 4 Bar. This has the effect of increasing the spring stiffness by a factor of 4.

A force scale could advantageously be marked on the outside of a transparent or translucent cylinder bore part 28 which can be read off against the centre line of the seal 41 on the divider 39. This would apply to the device operating at standard pressure.

Additional guide marks could be provided to quantify the degree of pressurisation for a small number of cycles, enabling further pressure scales to be read at these known pressure preloads. Similarly, the telescoping inner strut member 16 may carry a length scale, for example in the form of a series of indented marks with appropriate numerals in a column along the strut axis, the numerals adding in the fixed length of the outer strut member 15 and thus enabling the basic strut length, absent of spring compression or extension, to be read off where the markings intersect with the locking collar. This latter possibility is, of course, also applicable to the arrangement of Figure 4.Furthermore, each connection site of a connection element may be provided with a unique marking, numerical, alphabetical or otherwise, for facilitating the following of instructions for replicating previously designed structures.

Having thus described the invention by reference to specific embodiments, it is to be well understood that the described embodiments are exemplary only and that modifications and variations are possible without departure from the spirit and scope of the present invention in its various aspects. For example, whereas the connector element of Figures 1A and 1B provides a generally spherical node for connection to struts accessing the node virtually from any direction, other connector elements can be made with fewer fixation sites providing restricted strut access. For example an eight fixture node would be useful for rectangular lattice modelling for example.

The advantage in any given application is a smaller connector element providing ideal fixture axis vectors. Nodes can also be produced for easy fixing to other surfaces; for example, a hemispherical node might have a flange for accepting screw fixings and/or might have a smooth surface for use with a double sided adhesive pad. Furthermore, whereas the invention has been described in the foregoing by reference to struts connecting via universal joint means to the connector elements (nodes), the invention also contemplates the provision of fittings other than struts which can be fitted to the node fixation sites either in the same manner as a strut end and including the universal joint means, or simply by provision of a rigid conforming screw plug without any universal joint means and with any realizable form or device attached. Non-pivotable struts could be provided in this manner.

As mentioned hereinbefore, over the years there have been many different construction sets offering various ways of assembling a framework, whether for toy, education or modelling applications. All of these products have been limited in the lengths and angles which can be supported. Some products have offered universal angles, but only by compromising stiffness with flexible struts and linkages. They have thus all been limited in their ability to model free form structures. The present invention avoids these disadvantages by providing a system which, inter alia, is capable of linking struts of variable lengths to nodes at any angle and with substantial rigidity.

It can be implemented in small, low cost plastic parts. With this versatility, any framework can be modelled, including geodesic, truss spaceframe, complex curved surface, etc. Furthermore, the system of the present invention provides an add-on component that provides for elastic suspension of the strut members, enabling sprung constructions where forces can be measured.

The system of the invention enables the development of a compatible computer software product that enables structures to be designed and modelled.

The software could offer a simple graphical user interface that enables frameworks to be accurately assembled from library items and new constructions.

The frameworks could then be stretched and otherwise modified. A set of build instructions relating to the real construction set can then be output. A software upgrade can be offered consistent with the suspension unit hardware upgrade enabling structures to be pinned and loaded, with force propagation throughout the structure predicted in terms of loads and individual suspension unit displacements. In this way structures can be designed and tested in a PC simulation environment, and the results compared to actual constructions under test thereby providing an important educational link. Also expansive creative structures become achievable at low effort.

Whilst the invention has been described by reference to toys and modelling, the system could be scaled-up and made in different materials to build larger scale structures and exhibition displays.

Furthermore, in the toy and modelling field, component parts of the system according to the present invention could be configured so as to be interconnectable with components of other available systems, such as the LEGOz and K'NEXw systems aforementioned, thereby enhancing the versatility of other available systems.

Claims (45)

CLAIMS:

1. A constructional system comprising gripping sockets adapted to engage with the ends of elongate struts by means of universal joints providing for a substantial degree of freedom of movement of the struts relative to the gripping sockets, and wherein locking means are provided for locking the universal joints.

2. A constructional system as claimed in claim 1 wherein said universal joints comprise ball-andsocket joints.

3. A constructional system as claimed in claim 2 wherein the balls of the ball-and-socket joints are provided at the strut ends and are each adapted to be received in an accommodating complementary recess in a locking member, such recess defining the socket of the ball-and-socket joint, and the locking member is adapted to be received in a gripping socket.

4. A constructional system as claimed in claim 3 wherein the locking members are adapted to be screwthreadedly received in the gripping sockets.

5. A constructional system as claimed in claim 3 or 4 wherein the insertion of the locking member into the gripping socket is arranged to tighten the socketdefining recess of the locking member about the ball end of a strut.

6. A constructional system as claimed in claim 3 or 4 or 5 wherein the gripping socket is generally conical and the locking member has a generally conical external shape complementary to the conical shape of the gripping socket.

7. A constructional system as claimed in any of the preceding claims wherein the gripping sockets are provided in or on connector elements of the system.

8. A constructional system as claimed in claim 7 wherein said connector elements include means engageable transversely with one or more of said struts.

9. A constructional system as claimed in any of the preceding claims wherein said elongate struts are of adjustable length.

10. A constructional system as claimed in claim 9 wherein said elongate struts are telescopically adjustable.

11. A constructional system as claimed in claim 10 wherein the adjustable length struts include locking means enabling them to be locked at an adjusted length.

12. A constructional system as claimed in claim 11 wherein a locking collar is screw-threadedly engaged with the end of the outer one of two elongate telescopic members constituting the strut, tightening of the locking collar being arranged to lock the two telescopic members.

13. A constructional system as claimed in claim 12 wherein a wedge ring is provided within the locking collar, tightening of the locking collar being arranged to urge the wedge ring radially inwards into locking engagement with the inner one of the two telescopic members.

14. A constructional system as claimed in claim 13 wherein the inner one of the two telescopic members is externally screw-threaded and a complementary screw thread is provided on a facing surface of the wedge ring.

15. A constructional system as claimed in any of the preceding claims wherein said elongate struts include means enabling them to be elastically compressed and/or extended about a set length.

16. A constructional system as claimed in claim 15 wherein said means enabling struts to be elastically compressed and/or extended comprises compression and/or tension springs associated with relatively movable strut parts.

17. A constructional system as claimed in claim 15 wherein said means enabling struts to be elastically compressed and/or extended comprises pneumatic means associated with relatively movable strut parts.

18. A constructional system as claimed in claim 17 wherein said pneumatic means comprises a pneumatic component having first and second parts defining between them a sealed chamber, one of said parts being adapted for connection to a first strut part and the other being adapted for connection to a second strut part, the arrangement enabling relative lengthwise movement of said first and second strut parts with pneumatic compression and/or expansion of said chamber.

19. A constructional system as claimed in claim 18 wherein said first and second parts of said pneumatic component comprise inner and outer cylindrical parts received one within the other and movable axially relative to each other, said inner and outer cylindrical parts defining between them at least one said chamber which is delimited by seals which permit the axial extent of the chamber to be varied with pneumatic compression and/or expansion of the at least one chamber.

20. A constructional system as claimed in claim 19 wherein said inner and outer cylindrical parts define first and second chambers which are sealed from each other in the axial direction, the arrangement being such that relative axial movement of said inner and outer cylindrical parts serves to compress one of said chambers and expand the other.

21. A constructional system as claimed in claim 20 wherein first and second ports are provided which access said first and second chambers, and means are provided which enable the open/closed condition of said ports to be selectively determined.

22. A constructional system as claimed in claim 21 wherein said means enabling the open/closed condition of said ports to be selectively determined comprises a member whose rotational condition relative to the pneumatic component is adjustable, said member having formations co-operating with said ports to determine their open/closed condition.

23. A constructional system as claimed in claim 22 wherein said member comprises part of an elongate strut of the system.

24. A constructional system as claimed in claim 21 or 22 or 23 wherein the arrangement of said ports and of said means enabling the condition of said ports to be selectively determined is such as to enable the pressure in one and/or the other of said pneumatic chambers to be pumped.

25. A constructional system as claimed in any of claims 19 to 24 wherein said inner and outer cylindrical parts of said pneumatic component are connected to or adapted to be connected to respective parts of a telescopic strut.

26. A constructional system as claimed in claim 25 and wherein the connection of one of said inner and outer cylindrical parts to the respective part of a telescopic strut is an adjustable connection enabling the nominal strut length to be adjusted.

27. A constructional system as claimed in claim 26 wherein said adjustable connection comprises a locking collar screw-threadedly engaged with one of said inner and outer cylindrical parts and extending around one part of the telescopic strut, tightening of said locking collar serving to grip said one telescopic strut part.

28. A constructional system as claimed in claim 27 wherein a wedge ring is provided within the locking collar, tightening of the locking collar being arranged to urge the wedge ring radially inwards into locking engagement with said one telescopic strut part.

29. A constructional system as claimed in claim 28 wherein the external surface of said one telescopic strut part is screw-threaded and the facing surface of the wedge ring is complementarily screw-threaded.

30. A constructional system as claimed in any of the preceding claims and wherein the gripping sockets, the elongate struts, the universal joints and the locking means are substantially as hereinbefore described with reference to Figures 1A, 1B, 2A, 2B and 3 of the accompanying drawings.

31. A constructional system as claimed in any of the preceding claims wherein the struts are of adjustable length and are substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.

32. A constructional system as claimed in any of the preceding claims wherein the struts have associated therewith pneumatic means substantially as hereinbefore described with reference to Figure 7 of the accompanying drawings.

33. A constructional system as claimed in any of the preceding claims further comprising one or more fittings, other than struts, which can be fitted to said gripping sockets either with or without universal joints acting between the fittings and the gripping sockets.

34. A connector element for a constructional system as claimed in any of the preceding claims, said connector element incorporating one or more of said gripping sockets.

35. An elongate, fixed length strut for a construction system as claimed in any of claims 1 to 33.

36. An elongate, adjustable length strut for a connection system as claimed in any of claims 1 to 33.

37. A pneumatic component for a connection system as claimed in any of claims 17 to 29.

38. An elongate, adjustable-length strut comprising first and second telescopic members, a locking collar screw-threadedly engaged with one end of the outer telescopic member and a wedge ring within the locking collar, the arrangement being such that tightening of said locking collar onto said one end of the outer telescopic member causes said wedge ring to be urged inwardly so as to grip the inner telescopic strut member.

39. A strut as claimed in claim 38 wherein the outer surface of the inner telescopic strut member and the facing inner surface of the wedge ring are provided with complementary screw threads.

40. A strut as claimed in claim 38 or 39 wherein the wedge ring is circumferentially split so that it can close around the inner telescopic strut member when the locking collar is tightened.

41. A construction system as claimed in any of claims 1 to 33 configured as a child's toy, or component parts for such a system.

42. A construction system as claimed in any of claims 1 to 33 configured as a modelling system, or component parts for such a system.

43. A construction system as claimed in any of claims 1 to 33 configured for the construction of exhibition display stands and other temporary building constructions.

44. A constructional system as claimed in any of claims 1 to 33, or component parts for such a system, wherein component parts of the system are adapted to be interconnectable with component parts of other, different constructional systems.

45. A constructional system substantially as herein described with reference to the accompanying drawings.