The present invention relates to an accessory for magnetic construction games, and in particular to an accessory which allows the mutual movement of one or more member groups of a magnetic construction game.

WO 99/60583 and DE-U-20208736 disclose magnetic construction games comprising a plurality of magnetic bars suitable for being mutually joined by means of ferromagnetic spheres so as to made up a complex structure.

WO 02/055168 and WO 02/076565 disclose instead some accessories for said magnetic game, which serve for reinforcing the joining between the magnetic bars and the ferromagnetic spheres.

However, the structure made up of the magnetic bars, the ferromagnetic spheres and the relevant accessories is substantially static, i.e. does not allow a smooth mutual movement of the members, so that the user's fun is limited with respect to other construction games of the dynamic kind.

It is therefore an object of the present invention to provide an accessory which overcomes said disadvantage, i.e. an accessory which allows the mutual movement of one or more member groups of a magnetic construction game of the above mentioned kind. Said object is achieved with an accessory, the main features of which are disclosed in the first claim, while other features are disclosed in the subsequent claims.

Thanks to the ferromagnetic ring and to the ferromagnetic hub, the accessory according to the present invention can be inserted into a complex structure of the magnetic game for allowing the mutual movement of some parts thereof, so that this structure is not static but dynamic.

Furthermore, thanks to the particular shape, material and/or size of the ring and the hub, the accessory according to the present invention can be added to a known magnetic game without any modification of the existing members nor aesthetic or modularity problems.

According to a particular aspect of the invention, the accessory according to the present invention can be employed not only for the mutual movement of the parts of a composite structure, but also as a wheel of pulley, so that this structure can slide on any surface or being employed for pulling threads. For this purpose, the ferromagnetic ring of the accessory according to the present invention comprises an outer groove in which a thread can be wound or pulled or a rubber ring can be inserted for improving the sliding on said surface.

Further advantages and features of the accessory according to the present invention will become clear to those skilled in the art from the detailed and non-limiting description of two embodiments thereof with reference to the attached drawings, wherein:

• figure 1 shows a side view of the accessory according to the first embodiment of the present invention;
• figure 2 shows a front cross-sectioned view along plane II-II of the accessory of figure 1;
• figure 3 shows a front view of the accessory of figure 1;
• figure 4 shows a side view of the accessory according to the second embodiment of the present invention;
• figure 5 shows a front cross-sectioned view along plane V-V of the accessory of figure 4; and
• figure 6 shows a front view of the accessory of figure 4.

Referring to figures 1 to 3, it is seen that the accessory according to the first embodiment of the invention comprises a ferromagnetic ring 1 and a ferromagnetic hub 2 which is suitable for being arranged in a coaxial manner in the middle of this ring. Ring 1 has a substantially cylindrical profile, as well as a groove 3 along the outer cylindrical surface and/or a groove 4, 5 on one or both circular lateral surfaces. Furthermore, the inner radius R of ring 1 is substantially equal to the sum of the length of the known magnetic bars 6 and the radius of the known ferromagnetic spheres 7, so that two mutually aligned magnetic bars 6 and a ferromagnetic sphere 7 arranged between these bars can be firmly applied inside ring 1. The inner radius R is in particular comprised between 20 and 22 mm or between 31 and 33 mm.

Hub 2 comprises in turn a ferromagnetic member 8 having a substantially cylindrical shape pivoted by means of a pin 9 between two ferromagnetic members 10, 11 having a substantially hemispherical shape. For this purpose, pin 9 is arranged in a rotating manner in an axial hole, i.e. perpendicular to the center of the circular plane surfaces, made in the ferromagnetic members 8, 10, 11, so that the latter can rotate in an independent matter in the direction indicated by the arrows of figure 2 around the longitudinal axis A of pin 9, which substantially coincides with the axis of ring 1. For preventing the longitudinal sliding of the ferromagnetic members 8, 10, 11 in the axial holes, pin 9 is provided with circular protrusions arranged in corresponding seats made in the axial holes of the ferromagnetic members 10, 11 close to the curved surfaces. Pin 9 is made of steel or brass, while the ferromagnetic members 8, 10, 11 are made of steel, with a high percentage of ferrite. The magnetic bars 6 can thus be applied to any point of the hemispherical or cylindrical surface of the ferromagnetic members 8, 10, 11, so as to allow the mutual rotation of these bars around axis A.

The outer cylindrical surface of the ferromagnetic member 8 is preferably provided with a groove 12. The width w of grooves 3, 4, 5 and/or 12 is substantially equal to the diameter of the magnetic bars 6, in particular comprised between 5 and 7 mm, so that an end of these bars can be inserted into one of these grooves. The inner radius r of the ferromagnetic member 8 comprised between its axis and the throat of groove 12 is substantially equal to the radius of the ferromagnetic spheres 7.

The hemispherical surface of the ferromagnetic members 10, 11 is preferably provided with a plurality of holes 13 in which an end of the magnetic bars 6 can be inserted. The inner radius r of the ferromagnetic members 10, 11 comprised between their center and the bottom of holes 13 is substantially equal to the radius of the ferromagnetic spheres 7, in particular comprised between 6 and 7 mm.

Referring to figures 4 to 6, it is seen that the accessory according to the second embodiment of the invention comprises, as in the first embodiment, a ferromagnetic ring 1 and a ferromagnetic hub 2 arranged in a coaxial manner in the middle of this ring. However, ring 1 is joined to hub 2 by means of a plurality of fixed spokes 14. Furthermore, the two ferromagnetic members 10, 11 having a substantially hemispherical shape pivoted to hub 2 have an outer radius r substantially equal to the radius of the ferromagnetic spheres 7. Furthermore, a rubber ring 15 which projects beyond the outer cylindrical surface of ring 1 can be arranged in the outer groove of this ring.

Further variations and/or additions may be made by those skilled in the art to the embodiments hereinabove described and illustrated, while remaining within the scope of the invention as defined by the appended claims.