The invention concerns a building block system, in particular a toy building block system, comprising a plurality of inter-connectable building blocks, whereby each building block comprises on at least one lateral surface an undercut trough-shaped groove into which a connection bar with a cylindrical part can inserted.
Building blocks exist for the construction of static objects, whereby these building blocks are merely set on top of or alongside each other without any connection means. The static objects erected with such building blocks lack cohesion, so that they can collapse in the event of vibration.
Building block systems are known in many different embodiments. The building blocks in such building block systems are of differing geometrical forms and are usually connected with each other and assembled into building units by means of tip-stretched coupling members. In addition, toy building blocks are known which are generally combined in large numbers in toy building block systems, or toy building block sets to permit users to combine the toy building blocks into any desired structures and forms. These building blocks are generally made of plastic and often also of metal, wood, stone or the like. In particular if the building blocks are made of plastic they can be assembled into virtually any desired form.
Particularly plastic plug building blocks for playing purposes were until now connected with each other by providing tip-stretched connector elements on the building blocks themselves for plugging and connecting the building blocks to each other. For example, a plug building block is known from the EP-0 492 067 B1 as part of a toy building set in which tip-stretched spring-elastic clamp bars are arranged on the lateral surfaces of the building block. On at least one other lateral surface the building blocks comprise protruding spring plates which can be brought into spring engagement with the clamp bars of another plug building block.
The AU-B 12329/76 discloses a building block system whereby each building block comprises a plurality of protruding nubs on its surface. On its rear, each building block has a plurality of recesses into which the protruding nubs of another building block can be inserted. Many other similar plug building block systems are known.
From the DE-AS-14 78 380 a rectangular toy building block of square diameter is known which comprises one connection groove each on every lateral surface, whereby said groove extends in longitudinal direction and comprises an undercut connecting groove on one end surface and an undercut connecting bar on the other end surface. The undercut grooves are formed as tubular expanding slits into which the connection bar of another building block can be inserted. The connection bar of one building block must thereby be pressed into the connection groove of the other building block with great force because the undercut edges on the connection groove must be slightly widened since the space between the undercut edges of the connection groove is smaller than the width of the connection bar. In particular in plastic building blocks the connection bar or the undercut edges of the connection groove are thereby compressed and deformed. This limits repeated use of the connection elements. If the space between the opposite undercut edges of the connection groove is widened, the connection overall becomes unstable. In addition, the connection bar of one toy building block can be inserted into the undercut groove of another toy building block from the open end of the same. But inserting the connection bar in the groove requires a certain amount of dexterity.
Until now most developments focussed on different forms of building blocks connected by the same tip-stretched coupling members. Depending on the intended use, building blocks of different forms for walls, roofs, vehicles and the like are always connected to each other by the same tip-stretched connection elements to obtain a variety of combination options.
The problem of the present invention is to provide a building block system of the type described above which can be used for a variety of purposes, is easy to handle and permits a multiplicity of form-locking connection options of two or more building blocks, including of building blocks of differing geometrical form.
According to the invention, this problem is solved in that the connection bar is fitted with a hammer head-shaped boundary body on at least one end of the cylindrical part, whereby said hammer head-shaped body can be inserted into a corresponding recess on the end of the groove in the building block in form-lock with the lateral surface of the same when the connection bar snaps into the groove of the building block. Building blocks of uniform shape, e.g. square blocks, can thereby be connected with each other by separate connection elements of different forms. In addition, building blocks of differing geometrical form, e.g. squares, cubes, semi-cubes, equilateral triangles or cylindrical or wheel-shaped building blocks can be connected with each other. Figures of virtually any desired form, e.g. model vehicles, houses and the like, can thereby be built. The building block system according to the invention is suited preferably for toy building blocks, in particular for children. The building block system can, moreover, be used in furniture construction, fair construction, shop construction and steel construction, and in interior construction as well as for windows, doors, circuit casings etc., without this list being in any sense restrictive. Principally any kind of static object can be built with this building block system. The hammer head-shaped boundary bodies on the ends of the cylindrical part of the connection bar ensure that, during connection of the building blocks by insertion of the connection bar in the building blocks to be connected, a form-locking smooth surface of the connected building blocks is generated, because the hammer head-shaped boundary bodies come into engagement with the corresponding recesses on the ends of the grooves in the building blocks when the connection bar snaps into the grooves of the building blocks, without the hammer head-shaped boundary bodies protruding in any way from the lateral surfaces of the building blocks.
Depending on the intended use of the building block system determined by the static object to be created, the connection bar may comprise at least one cylindrical part or two cylindrical parts arranged in parallel or at least two cylindrical parts arranged at right angles with each other. Building blocks of differing geometrical form can thereby be assembled into different static objects.
According to a preferred embodiment of the invention, the undercut trough-shaped groove consists of two clamp-like grip walls lying opposite each other for receiving the cylindrical part of the connection bar, whereby said grip walls form an essentially tulip shape and are spring-elastic. Tulip shape according to the invention refers to the cross-section of the undercut trough-shaped groove which is substantially circular in form, whereby the two juxtaposed clamp-like grip walls extend beyond the nominal diameter of the circle cross-section and leave an aperture on top. Since the nominal diameter of the trough-shaped groove is therefore not entirely enclosed by the two grip walls, the cross-section presents a tulip-shaped groove. As a result, the grip walls are also spring-elastic. The cylindrical part of the connection bar abuts by its cylinder surface on the elastic contact surfaces of the clamp-like grip walls of the trough-shaped groove when two building blocks are connected to each other. This causes a certain surface pressure between the grip walls of the groove and the connection bar and low wear and tear during connection and disconnection of the building blocks. As a result of the large contact surfaces between the clamp-like grip walls of the trough-shaped groove and the corresponding cylindrical connection bar, sufficient cohesion forces are generated between the connected building blocks despite the low surface compression. A further advantage is that the building block system according to the invention permits easy connection of building blocks in radial direction between the groove and the connection bar. Due to the closed cylindrical form of the connection bars and the lateral surface of the building blocks, the connection is, moreover, very stable.
The undercut trough-shaped groove is advantageously arranged in a channel formed in the lateral surface of the building block, whereby the recesses for receiving the hammer head-shaped boundary bodies which flush-close with the lateral surface of the building block in assembled state of the connection bar are formed on the free ends of the clamp-like grip walls of the groove. The trough-shaped groove defined by the clamp-like grip walls is therefore enclosed in the building block and protected against external damage. In addition, the spring-elastic clamp-like grip walls are permitted to move sufficiently in radial direction in relation to their longitudinal axis during insertion of the cylindrical connection bar. The undercut trough-shaped groove is advantageously formed in one piece with the channel formed in the lateral surface of the building block. This combination of the groove with the channel is particularly easy to realize in the case of plastic profile bars or plastic building blocks due to the good forming properties of plastic.
To prevent violent over-extension or breaking of the clamp-like grip walls of the trough-shaped groove, the channel formed in the lateral surface of the building block is provided with two juxtaposed stops to limit the spring path of the clamp-like grip walls of the groove. This limits the spring action of the grip walls during insertion of the connection bar.
The tulip shape of the undercut trough-shaped groove particularly also derives from the fact that an integrated bar connects the groove to the channel formed in the lateral surface of the building block. This measure provides the trough-shaped groove with a further spring option in the form of the bar.
To increase the stability and clamp effect of the grip walls, the grip walls of the undercut trough-shaped groove are respectively partly thickened.
It is evident that the features described above and to be commented in detail below can be used not only in the combination respectively specified, but also in other combinations or on their own, without going beyond the scope of the present invention.