Background Art Assembly kits comprising wood and/or plastic building blocks, from which by means of plug-type, ribbed pin-type or threaded coupling members various dimensional formations and toy structures can be constructed are known in a large variety. For a number of the well-known assembly kits, it is necessary to apply a certain tool, generally a single purpose tool (screwdriver, pliers, hammer or other pushing or pulling means) for disassembling the constructed formations. For example, the published German patent application DE 33 05 518 describes a pin-type coupling member for which a special tool is applied for dismounting. Hungarian patent specification No. 181 256 introduces a tubular coupling member split along its generatrix, whereby the coupling member is allowed to certain flexible compressibility. In a direction normal to the longitudinal split the coupling member is provided with several incisions, and one of these incisions can be associated with a plug element having a retaining rib when inserted into a located crosswise to the bore receiving the coupling member. This known coupling member design has the disadvantage that on the one hand it is requires the use of a separate tool, while its design and thus, its handling are quite complicated on the other.

A further assembly kit for constructing figural bodies and especially toy figures is described in Hungarian patent specification No. 186 437. The coupling members of this assembly kit are threaded pins that can be handled even without the use of an additional tool. The coupling members are associated with correspondingly threaded disk-like nuts.

Especially for smaller children, however, the use of such multi-component coupling members causes difficulties and a frequent feeling of failure.

Hungarian patent specification No. 186 437 refers in its paragraphs in which the background art is dealt with to the possibility of using wooden pins as coupling members that are provided with longitudinal slots. In said reference to slotted wooden pins however, the necessary use of additional tools, primarily hammer and pliers for their handling is also included.

US patent No. 3 803 754 discloses an assembly kit comprising a plurality of prismatic building blocks with non-circular slits and flat connectors. For the purpose of combining non-circular and circular portions for connecting rotatable parts such as wheels and levers, other connecting elements having a connecting portion of generally circular cross-sectional configuration adapted to be inserted into a generally cylindrical socket in a rotary component such as a wheel or the like are also described. The US patent also refers to the connecting portion of said other connecting elements comprising two widened spreaders separated by a longitudinal slot.

Disclosure of the Invention The main object of the present invention is to create an assembly kit, which is suitable even from the age of four on to develop children's spatial vision and manual skills, without the necessity for complicated coupling members of difficult and clumsy handling that would make an adverse effect on these skills.

This and other objects of the invention are fully met by the provision and the use of an assembly kit comprising a plurality of building blocks of generally rectilinear configuration, connecting plates of elongate rectangular shape, and optional further elements such as e. g. wheels and wheel shafts. The building blocks, connecting plates and optional further elements of the assembly kit are, at least preferably, made of wood, and the building blocks have a generally prismatic shape confined by substantially plane faces. At least one of the plane faces of the building blocks comprises at least two transverse grooves of pre-determined depth, capable of receiving, in a releasable manner, at least one connecting plate of the assembly kit for interconnecting at least a pair of adjoining building blocks. The at least two transverse grooves in the plane faces of the building blocks are recessed into the plane faces in parallel arrangement with respective sides of said plane faces, said sides forming respective edges of the building blocks.

According to the novel and essential features of the invention the building blocks of the assembly have the shape of a cube of a pre-determined edge length, or of an elongate rectangular prismatic body having, as a base face, a plane face of rectangular shape confined by two sides of a length equalling each, an integer multiple of one-half of said pre-determined edge length of said cube. The building blocks of the shape of an elongate prismatic body have a height that is equal again, to an integer multiple of one-half of said pre-determined edge length of said cube. The transverse grooves have an equal depth that is less than one-half of the pre-determined edge length of the cube, and the grooves are recessed into the at least one plane face of the building blocks in a manner so that they extend all along said plane face between pair-wise opposite sides thereof. The assembly kit also comprises coupling members having a substantially cylindrical shaft section. The coupling members may have a head portion of enlarged diameter at one end of the substantially cylindrical shaft portion. In preferred embodiments, the shaft portion of the coupling members terminates in a pair of widened, substantially elastic spreaders separated by a longitudinal slot. The building blocks as well as the connecting plates are provided with a number of thoroughfare bores capable of fittingly receiving the cylindrical shaft sections of said coupling members. The thoroughfare bores of the building blocks intersect the grooves by being perpendicular to and in parallel arrangement with respective plane faces of the building blocks, and the bores in the connecting plates are in axial alignment with the bores of the building blocks when a connecting plate is inserted, into any of the grooves of the building blocks, in its position interconnecting adjacent building blocks of the assembly kit.

Preferred embodiments of the assembly kit according to the invention providing more room for construction ideas for the children's manipulation abilities and for creativity, may also comprise at least one additional building block that is generated either from a building block having a shape of a cube or an elongate prismatic body by cutting away an edge portion of the cube or the prismatic body along a section plane enclosing an acute angle with one of the plane faces of the cube or the prismatic body.

The section plane should be parallel with or include at least one of the edges of the building block concerned.

At least one of the building blocks, preferably at least one of the building blocks having the shape of an elongate prismatic body may also include at least a pair of shaft bores of a diameter that is at least equal to that of the thoroughfare bores of the building blocks.

Further preferred embodiments of the assembly kit according to the invention may, as further elements, comprise at least a pair of wheel sets, each of them consisting of a wheel body and a wheel shaft. The wheel body has a central bore and at least one lateral spacer shoulder, while the wheel shaft has a shaft body to be inserted, with substantially tight fit, into one of the shaft bores of a building block. The wheel shaft also has an axle portion terminating in a pair of widened spreaders separated by a longitudinal slot, and the axle portion of the wheel shaft is receivable, under loose fit, by the central bore of the wheel body.

Brief Description of the Drawings The invention will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings in which, Fig. 1 is a top view showing by way of example only two identical cube shaped building blocks of the assembly kit according to the invention, said building blocks being joined together via a connecting plate and two coupling members as one possible approach of creating a simple toy structure, Fig. 2 is a side view depicting by way of example again, another simple structure assembled from a building block having the shape of a cube and another building block of the shape of an elongated prismatic body, by using an elongated connecting plate and four coupling members so as to arrive at the structure shown, Fig. 3 shows in elevation, a possible embodiment of a wheel set comprising a wheel body and a wheel shaft, which form by way of example, optional further elements of the assembly kit of the invention, Fig. 4 illustrates in enlarged elevation a detail of the wheel shaft of the wheel set shown in Fig. 3, Fig. 5 depicts in elevation and by way of example only, a side view of a preferred embodiment of a coupling member of the assembly kit of the invention, Fig. 6 is another side view of the coupling member turned by 90° with respect to what is shown in Fig. 5, Fig. 7 is an enlarged end view of the coupling member shown in Figs. 5 and 6, while Fig. 8 is a distant perspective view of a toy vehicle constructed by way of example only from a number of typical building blocks, connecting plates, coupling members and wheel sets of the assembly kit embodying the invention.

Best Mode for carrying out the Invention Fig. 1 of the attached drawing shows two cube-shaped building blocks 10 of the assembly kit embodying the invention and one of their possible connections by way of example only, while Fig. 2 of the drawing depicts a simple structure comprising a cube- shaped building block 10 and another building block 11 having the shape of an elongate rectangular prismatic body. The building block 11 shown in Fig. 2 has a height that is equal to two cube edge lengths. As it can be seen in Figs. 1 and 2, perpendicular grooves 13 are recessed into all of the side faces confining the building blocks 10 and 11. All transverse grooves 13 have an equal depth that is less than one-half of the edge length of the cube-shaped building block 10, and the grooves 13 are recessed into the plane faces of the building blocks 10 and 11 in a manner extending all along the plane faces between pair-wise opposite sides. Figs. 1 and 2 of the drawing further indicate connecting plates 20 and coupling members 30 of the assembly kit of the invention. It is apparent that the building blocks 10,11 as well as the connecting plates 20 are provided with thoroughfare bores 14 capable of fittingly receiving cylindrical shaft sections 32 of the coupling members 30 shown in Figs. 5 and 6. The thoroughfare bores 14 intersect the grooves 13 of the building blocks 10 and 11, and they are perpendicular to and in parallel arrangement with respective plane faces of the building blocks 10,11. Thoroughfare bores 21 in the connecting plates 20 are in axial alignment with the bores 14 of the building blocks 10,11 when a connecting plate 20 is inserted in aligned grooves 13 of the building blocks 10,11 in its position interconnecting adjacent building blocks 10 and 11.

The thoroughfare bores 14 of the building blocks 10,11 are arranged at equal distances from their edges, and the distance measured between an edge of the building blocks 10,11 and the centrelines of the bores 14 arranged nearest to said side edge are substantially equal to one-half of the depth of the grooves 13 in the building blocks 10, 11. For a cube-shaped building block 10 this means that the grooves 13 are located in the halving planes of the cube. In the building block 11 of the shape of an elongated prismatic body, the grooves 13 located in the two extreme positions when viewed in the direction of the largest dimension are also recessed at distances of one-half of the cube edge length when measured from opposite side edges of the building block 11. The building block 11 shown in Fig. 2 has a height equal to six times the one-half edge length of the cube, and the grooves 13 of its middle portion are spaced from each other at distances equal to the edge length of the cube. The two cube-shaped building blocks 10 shown in Fig. 1 as well as the building blocks 10 and 11 shown in Fig. 2 are joined by a connecting plate 20 which has a thickness that fits into that of the grooves 13. The width of the connecting plates 20 of elongate rectangular shape is equal to the double depth of the grooves 13 in the building blocks 10 and 11, and the connecting plates 20 have the length of at least two or more integer multiples of one-half of said pre-determined edge length of a building block having the shape of a cube. For example, Fig. 2 depicts a connecting plate 20 of a double cube edge length. Further building blocks of the assembly kit can be joined to the section of the connecting plate 21, which section protrudes when seen in the drawing, in upward direction and contains four bores 21 not yet used, i. e. being still free for joining another building block of the toy structure to be created.

A preferred embodiment of the coupling members 30 is shown by way of example in Figs. 5 to 7 of the attached drawing. The coupling member 30 has a cylindrical shaft portion 32 having a head portion 31 of increased diameter at its one end.

The other end of the coupling member 30 has a pair of spreaders 33 each of said spreaders having end portions of semi-spherical shape increasing to a diameter larger than that of the cylindrical shaft portion 32. A slot 34 lying in the halving plane is recessed into a part of the shaft portion of the coupling member 30 from the direction of the ends of the spreaders 33. The semi-spherical ends of the spreaders 33 of the coupling members 30 have a flattened design on both sides normal to the plane of the slots 34.

The length of the cylindrical shaft portion 32 of the coupling member 30 is substantially equal to one and the half times the one-half edge length of the cube-shaped building blocks 10, and the slot 34 is of a depth of at least one-half of the length of the cylindrical shaft portion 32 when measured in axial direction. Due to their preferred design shown in Figs. 5 to 7, the coupling members 30, when inserted in the bores 14 of the building blocks 10 and 11 are capable of joining, in a reliable way resisting to light pulling forces, the respective building blocks 10,10 and 10,11 with connecting plates 20 inserted in the grooves 13. In the course of pushing in and pulling out, the coupling member 30 would not get stuck in the bore 14. When it is pushed home, as a result of the slot 34 and the increased diameter of the substantially elastic spreaders 33, it is will be slightly compressed, and due to the elastic deformation it provides a reliable retaining fit. The head portion 31 of the coupling members 30 provides for a good grip, so that they can be easily pulled out and handled manually, without the need for applying extreme force or a single-purpose tool.

Depending on the types and the number of building blocks included and actually used, the assembly kit according to the invention enables the creation of numerous toy formations which can easily be disassembled or converted to different shapes. Fig. 8 of the attached drawing depicts, by way of example again, a toy car assembled from an assembly kit of the present invention. This and other vehicles can be assembled from assembly kits, which in addition to the building blocks 10 and 11 already described also comprise a building block 12 of a different, not fully rectangular shape. Building block 12 is generated for example from a building block 11 by cutting away one of its edge portions along a section plane enclosing an acute angle with a basic plane face of building block 11. The assembly kit may also comprise building blocks of other shapes generated for example from a cube-shaped building block 10 or from building blocks of other different shape, portions of which are cut away along one or more other acute section planes. From such further building blocks (not shown) e. g. structures resembling roofs of buildings etc. can be created. The building block 11 of the assembly kit suitable for assembling a toy car as shown in Fig. 8 has a longitudinal dimension equal to the length of three cube edges. It also contains three shaft bores 15 of a diameter larger than that of the bores 14. Two of such shaft bores 15 are used for receiving and retaining shaft bodies 51 of a wheel shaft 50 of a wheel set shown by way of example only, in Figs. 3 and 4 of the attached drawing. The wheel set shown includes a wheel body 40 and a wheel shaft 50. The wheel body 40 has a central bore 42 and a lateral spacer shoulder 41.

The wheel shaft 50 has, as shown in Fig. 4, a shaft body 51 to be inserted, with a substantially retaining fit, into the shaft bores 15 of the building block 11 shown in Fig. 8. The wheel shaft 50 has an axle portion 52 terminating in a pair of widened spreaders 54 separated by a longitudinal slot 53. The axle portion 52 of the wheel shaft 50 is receivable, under loose fit, by the central bore 42 of the wheel body 40. The split spherical end pin-type design of the wheel shaft 50 is identical both in shape and function, with the slotted end design of the coupling members 30. The assembly shown in Fig. 8 by way of example only can be created and assembled even by small children very simply and within a short time, and the vehicle designed and assembled by the child him-or herself, can be immediately used as a toy.

Experience has shown that the assembly kit according to the present invention can be easily handled by children from the approximate age of four on. It enhances both the spatial vision and the manual skills of children, because assembling and disassembling toy structures from the building blocks and optional additional elements of the assembly kit are extremely simple, and the coupling members of the kit can be easily handled without the need for a tool. By joining the building blocks through pushing in and pulling out coupling members, the creation of simple three-dimensional formations provides to the children an immediate feeling of success which encourages them to continue with creating further structures of more complicated and thus, challenging shapes.