FIELD OF THE INVENTION The present invention relates to the technical sector of ring-wound conveyors for transport of articles; in particular, the invention relates to a ring-wound electromagnetic conveyor.

DESCRIPTION OF THE PRIOR ART Ring wound conveyors for transport of articles are known, which comprise a member for transport of articles which can be a chain, a cogged belt or a mat. As is known, these ring-wound conveyors are used in various industrial sectors, for example for moving raw materials or semi-finished pieces from a work station to another or towards storage magazines. In these conveyors the conveyor member winds, for example, about a drive pulley and a driven pulley, with the aim of enabling movement of the conveyor member itself, and thus of the articles placed on it.

The drive pulley receives the drive from a transmission shaft, which in turn is connected, via a speed reducer, to an electric motor. The overall performance of the conveyor is not high, depending on the performance of the speed reducer and on the performance of the electric motor.

Conveyors for transfer of articles as above-described further exhibit a size which in some applications, where small spaces only are available, can make their use problematic. A further drawback of the conveyors of the prior art is due to their relative noisiness and the limitation of the angular velocity of the drive pulley, with consequent repercussions on productivity. SUMMARY OF THE INVENTION

The aim of the present invention therefore consists in obviating the above- mentioned drawbacks.

In accordance with claim 1 , the above aim is attained with a ring-wound electromagnetic conveyor for transport of articles, comprising: a member for transporting articles, which develops in a closed ring and bears a plurality of permanent magnets; a rotatable support about which the transport member partially winds; a source of an electromagnetic field arranged in proximity of the rotatable support such as to interact with the permanent magnets of the portion of the transport member which winds about the rotatable support and determines a movement of the transport member.

The electromagnetic conveyor of the invention is advantageously quieter and can move the transport member at greater speeds than conveyors of traditional type, with a consequent increase in productivity. A further advantage of the invention consists in having created an electromagnetic conveyor which uses less C0 ₂ than conveyors of known type.

The arrangement of the electromagnetic source in proximity of the rotatable support about which the transport member winds advantageously enables maximising the electromagnetic interaction of the source with the permanent magnets of the transport member: the portion of transport member which winds about the rotatable support identifies a region of space having a greater concentration of permanent magnets, such as to optimise the electromagnetic interaction with the source of the electromagnetic field and thus the mechanical torque produced for moving the transport member. For this purpose, the source of the electromagnetic field can comprise a plurality of electromagnets or windings flowed-through by current, which are arranged such as to follow the geometric profile assumed by the portion of transport member which winds about the rotatable support such as to maximise the interaction of the electromagnets or the winds with the permanent magnets of the portion of transport member which winds about the rotatable support.

In an embodiment, the rotatable support comprises a mobile part, about which the transport member winds, and a fixed and hollow part, while the source of electromagnetic field is obtained: by inserting the stator of an electric motor into the fixed and hollow part of the rotatable support; and by adapting the stator of the electric machine such as to supply only the windings which follow the geometric profile assumed by the portion of transport member which winds about the rotatable support.

The use of a source of electromagnetic field to move the transport member thus advantageously requires neither the use of an electric motor nor a transmission shaft, nor a speed reducer. It follows that the overall sizes (especially the lateral sizes) of the electromagnetic conveyor of the invention are smaller with respect to those of conveyors of known type activated by an electric motor-speed reducer group; likewise, also the overall output of the electromagnetic conveyor of the invention is higher than that of conveyors of known type and described above. In other words, the electromagnetic conveyor thus obtained is an electric motor the rotor of which is constituted by the transport member.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the invention, and advantageous technical-functional characteristics correlated to these embodiments that are only partly derivable from the above description, will be described in the following, in accordance with what is set out in the claims and with the aid of the accompanying figures of the drawings, in which:

- figure 1 is a perspective view of the closed ring-wound electromagnetic conveyor of the invention, in which some parts have been removed better to evidence others;

- figure 2 is a plan view of the electromagnetic conveyor of figure 1 , from which some parts have been removed;

- figure 3 is a view in enlarged scale of section Ill-Ill of figure 2; - figure 4 is a view in enlarged scale of section IV-IV of figure 2;

- figure 5 is a view in enlarged scale of section V-V of figure 2;

- figure 6 is a perspective view of a rotatable support of the electromagnetic conveyor of the invention; - figure 7 is a section view of the rotatable support of figure 6;

- figure 8 is a plan view of an assembly of components of the conveyor of the invention;

- figure 9 is a view of section IX-IX of figure 8;

- figure 10 is a view of section X-X of figure 8; - figure 1 1 is a schematic lateral view of the closed ring-wound electromagnetic conveyor of the invention, according to a further embodiment, in which some parts have been removed better to view others;

- figure 12 is an enlarged-scale view of section XII-XII of figure 1 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to figures 1-10, number 1 denotes the closed ring-wound electromagnetic conveyor for transport of articles which is the object of the present invention.

The electromagnetic conveyor 1 comprises: a member 2 for transporting articles, which develops in a closed ring and bears a plurality of permanent magnets 3 distributed for example uniformly along its development; a rotatable support 4 about which the transport member 2 partially winds; and a source of an electromagnetic field 5 arranged in proximity of the rotatable support 4 such as to interact with the permanent magnets 3 of the portion of the transport member 2 which winds about the rotatable support 4 and determines a movement of the transport member 2.

The electromagnetic conveyor 1 further comprises a second rotatable support 41 making a total of two rotatable supports 4, 41 (figure 1 ); the source of the electromagnetic field 5, however, is arranged only in proximity of a rotatable support 4, which in the following will be indicated as the first rotatable support 4 (figures 2, 3) in order to distinguish it, where necessary, from the second rotatable support 41. However, the electromagnetic conveyor 1 can exhibit an even more complex configuration, for example with a greater number of rotatable support 4, 41 (this solution is not represented in the drawings).

In the illustrated example the transport member 2 is a chain for transport of articles (not shown), of known type, formed by a plurality of elements 6 that are interconnected to one another; each element 6 of the chain comprises a base 7 provided with a surface 8 for restingly receiving the articles and a stalk 9 which develops on a side of the base 7, opposite the rest surface 8 and which is hinged to the stalks 9 of the adjacent elements in order to form the chain 2. Each element 6 of the chain 2 can therefore rotate by a certain angle with respect to the adjacent one to which it is connected.

Each element 6 of the chain 2 exhibits a plane of symmetry A which divides the stalk 9 and the base 7 in half; when the elements 6 of the chain 2 wind about the rotatable supports 4, 41 (and therefore the electromagnetic conveyor 1 is predisposed for normal functioning) a single longitudinal plane of symmetry A of the chain 2 is defined.

The chain 2 further bears two rows of permanent magnets 3 which are arranged on opposite sides with respect to the longitudinal axis of development of the chain 2; in particular the two rows of permanent magnets 3 are arranged symmetrically with respect to the plane of symmetry of the chain 2. Each element 6 of the chain 2 can be provided with two permanent magnets 3, fixed for example at respective opposite sides with respect to the pin 10 of the element 6 of the chain 2 which realises the hinge between stalks 9 of elements 6 of chains 2 that are adjacent (figures 3, 5); the two permanent magnets 3 are therefore arranged symmetrically with respect to the plane of symmetry of the element 6 of the chain 2. Alternatively more than two permanent magnets 3 can be provided fixed to each element 2 of the chain 6, which can also exhibit alternating polarities for the purpose of moving the chain 2, as will emerge clearly from the following; for example, three permanent magnets 3 can be provided having alternating polarity (for example two polarities of a same type and one of the opposite type) arranged on each side of the plane of symmetry of the element 6 of the chain 2, for a total of six permanent magnets associated to each element 6 of the chain 2 (this example is not illustrated).

Figures 1 , 2 clearly show the shape of the base 7 of the elements 6 of the chain 2.

The rotatable support, first 4 and second 41 , has been represented isolated in figures 6, 7. It comprises an external mobile part 1 1 developing in a circular fashion, about which the chain 2 is destined to wind, and an internal fixed part 12, which is hollow; the external mobile part 1 1 can slide with respect to the internal fixed part 12 by means of ball bearings 13. In other words, the rotatable support 4, 41 can functionally be a ball bearing. The external mobile part 1 1 conforms a guide for guiding the winding of the chain 2. In particular, the mobile part 1 1 exhibits a circular base 14 and two lateral sides 15 having a circular development such as to create a sliding seating for the stalks 9 of the chain 2. The rotatable support 4, 41 exhibits a plane of symmetry B which coincides with the plane of symmetry of the chain 2 when the chain 2 winds about the rotatable support 4, 41 for the normal functioning of the electromagnetic conveyor 1 .

The electromagnetic source 5 can comprise a plurality of electromagnets or windings that can be flowed through by electric current, which are arranged such as to follow the geometrical profile assumed by the portion of chain 2 which winds about the first rotatable support 4 in order to maximise the interaction of the electromagnets or the windings with the permanent magnets 3 of the portion of chain 2 which winds about the first rotatable support 4. The windings or electromagnets are arranged in two parallel rows such as to interact respectively with the two rows of permanent magnets 3 of the chain 2 and thus determine the movement of the chain 2 itself.

In a further variant, not illustrated, the electromagnets or windings are arranged externally with respect to the closed ring defined by the chain 2. In the embodiment illustrated in the figures, the electromagnetic source 5 comprises two parallel rows of electromagnets 16 which are made solid to the internal fixed part 12 of the first rotatable support 4 and are arranged such as to realise respective magnetic circuits with the respective rows of permanent magnets 3 of the chain 2, minimising the air gap, in particular minimising the distance between each electromagnet 16 and the corresponding permanent magnet 3 of the chain 2 facing it, as will clearly emerge from the following description.

The electromagnetic conveyor 1 comprises a sleeve 19 which is coaxial to the first rotatable support 4 and is fixed to the internal fixed part 12 of the first rotatable support 4 in order to project from both sides with respect thereto (figure 3). The electromagnetic conveyor 1 further comprises a first and a second pack of small plates 17 made of a ferromagnetic material (figures 8-10). The plates 17 of each pack have the shape of a circular crown provided with projections or external poles 18 distributed uniformly along the whole circular development of the relative crown according to a step which is connected to the distribution of the permanent magnets 3 along the extension of the chain 2 (for example the step of each external pole 18 is equal to the longitudinal step between permanent magnets 3 of portions of chain 2 which wind about the rotatable support 4); each pack of plates 17 is obtained by superposing the plates 17 and fixing them to one another. The two packs of plates 17 are fixed to the sleeve 19, such as to be respectively on opposite sides with respect to the first rotatable support 4; in other words, the first rotatable support 4 is interposed between the two packs of plates 17 (see figure 3).

With reference to figure 3, the poles 18 project externally with respect to the first rotatable support 4, i.e. with respect to the circular base 14 and the two lateral sides 15.

The poles 18 of the two packs of plates 17 of the first rotatable support 4 which follow the geometric profile assumed by the portion of chain 2 winding about the first rotatable support 4 receive respective electrical windings 20 (figure 4); each electromagnet 16 is therefore formed by a pole 18 made of ferromagnetic material and by a conductor 20 spiral-wound about the pole 18. The remaining poles 18 about which the windings 20 are not applied are superfluous and in an embodiment (not represented) they can be absent. In this case it is sufficient to have a number of poles 18 (and windings 20 applied thereto) arranged to an angle which about 180 degrees, such as to follow the geometric profile of the portion of chain 2 which winds about the first rotatable support 4.

The two rows of electromagnets 16 are arranged symmetrically with respect to the common plane of symmetry A, B identified by the rotatable supports 4, 41 and by the chain 2 wound about the rotatable supports 4, 41. In particular, the electromagnetic conveyor 1 is designed such that each row of electromagnets 16 is aligned to the respective row of permanent magnets 3 of the chain 2 and such that the air gap is minimal, i.e. the distance between the row of electromagnets 16 and the facing row of permanent magnets 3 of the chain is minimal when the row of permanent magnets 3 winds about the first rotatable support 4. In the illustrated example (figure 3) the air gap is indeed constituted by air.

The alternative embodiment of the electromagnetic conveyor 1 illustrated in figures 1 1 , 12 is differentiated from the main one illustrated in the remaining figures only in that the permanent magnets 3 of the chain 2 are fixed directly to the stalk 9 of the elements 6 of the chain 2; in this case the air gap established between each row of electromagnets 16 and the respective row of permanent magnets 3 of the chain 2 when the chain winds about the first rotatable support 4 is greater (compare figure 12 with figure 3). The electromagnetic conveyor 1 further comprises two lateral closing covers 21 of each rotatable support 4, 41 (figure 3, 8, 9) and of the lateral structural bars 22 which are a part of the relative frame.

At the upper and lower branch of the electromagnetic conveyor 1 a profiled element 23 is provided, which forms a part of the relative frame of the electromagnetic conveyor 1 , which element 23 is designed such as to guide the chain 2 during the sliding thereof along the upper and lower branch, determining a magnetic levitating thereof. The element 23 extends over the whole length of the upper and lower branch of the electromagnetic conveyor 1 and terminates in proximity of the rotatable supports 4, 41 (figure 4, for the sake of simplicity, does not include the element 23).

The element 23 has two housings 24, 25 having a longitudinal development, i.e. a lower housing 24 for receiving the stalks 9 of the elements 6 of the chain 2 when the chain 2 slides along the lower branch and an upper housing 25 for receiving the stalks 9 of the elements 6 of the chain 2 when the chain 2 slides along the upper branch. Both the housings 24, 25 are C-shaped and exhibit an aperture for enabling insertion of the stalks 9 of the chain 2 (figure 5); the lower housing 24 has an upper wall, lateral walls and two lower tabs that are separated by the aperture, while the upper housing 25 has a lower wall, lateral walls and two upper tabs separated by the aperture. The element 23 has two planes of symmetry, of which a plane of symmetry C coinciding with the common plane of symmetry A of the chain 2 and of a plane of symmetry B of the rotatable supports 4, 41. The element 23 is provided with two rows of permanent magnets 26 fixed to the lower wall of the upper housing 25 and two rows of permanent magnets 27 fixed respectively to the lower tabs of the lower housing 24; the rows of permanent magnets 26, 27 are also arranged symmetrically with respect to the common plane of symmetry A, B, C mentioned above. The permanent magnets 26 of the upper housing 25 are arranged inferiorly with respect to the permanent magnets 3 of the chain 2 when the chain engages in the upper housing 25; further, the permanent magnets 26 further exert overall a repulsive force against the permanent magnets 3 of the chain 2 such as to cause magnetic levitation of the chain 2 when the chain 2 slides along the upper branch and transports articles of a predetermined weight.

The permanent magnets 27 of the lower housing 24 are arranged inferiorly with respect to the permanent magnets 3 of the chain 2 when the chain engages in the lower housing 24 (figure 5); the permanent magnets 27 further exert overall a repulsive force against the permanent magnets 3 of the chain 2 such as to cause magnetic levitation of the chain 2 when it slides along the lower branch. The dimensions of the magnets 26 of the upper housing 25 and the magnets 27 of the lower housing 24 can therefore be different given that in the first case it is necessary to magnetically levitate the chain 2 sliding along the upper branch and carrying articles, while in the second case it is necessary to magnetically levitate the chain 2 which slides along the lower branch and which does not transport articles.

Each row of permanent magnets 26, 27 interacts with the respective row of permanent magnets 3 of the chain 2 which is facing it; the gap is constituted by air and is as small as possible (figure 5). Both the rows of permanent magnets 26, 27 are arranged externally with respect to the respective rows of permanent magnets 3 of the chain 2 such that each row of permanent magnets 26, 27 of the element 23 exerts repulsive forces against the respective row of permanent magnets 3 of the chain 2 such as to comprise a transversal force component orientated towards the inside (thus towards the common plane of symmetry A, B, C) which tends to maintain the chain 2 centred during its sliding along the upper branch or the lower branch of the electromagnetic conveyor 1. The external arrangement of the rows of permanent magnets 26, 27 of the element 23 with respect to the opposite rows of permanent magnets 3 of the chain 2, has the further advantage of minimising the reciprocal interaction between rows of permanent magnets 26, 27 of the element 23 which are arranged in a same housing 24, 25; in other words, the row of permanent magnets 26 of the lower housing 24 will establish a negligible interaction with the other row of permanent magnets 26 of the lower housing 24, thus simplifying the design and dimensions of the permanent magnets 26, 27 of the element and the permanent magnets 3 of the chain 2 in order to realise magnetic levitation of the chain 2. The upper and lower tabs respectively of the upper housing 25 and the lower housing 24 are for example made of a suitable material (for example polyzene) for facilitating sliding of the stalks 9 of the chain 2 in a case of contact, thus minimising the friction produced thereby.

The windings 20 of the electromagnets 16 are appropriately connected to one another such that when current flows through them the magnetic interaction which is established with the permanent magnet 3 of the chain 2 winding about the first rotatable support 4 determines the movement of the chain 2. The current which flows through the windings 20 can be determined in similar ways to the current which is to flow through the windings of the stators of asynchronous motors or step motors or brushless motors. To activate step or brushless motors, permanent magnets 3 of the chain 2 can be provided having alternated polarities (though always such as to determine repulsive magnetic forces with the magnets 26, 27 of the element 23 such as to realise magnetic levitation of the chain 2 along the upper and lower branches).

In a further embodiment, not illustrated, the source of the electromagnetic field 5 is obtained by: inserting the stator of an electrical machine into the fixed and hollow part 12 of the first rotatable support 4; and adapting the stator of the electric machine such as to supply only the windings which follow the geometric profile assumed by the portion of chain 2 which winds about the first rotatable support 4.

The electric machine can be an electrical step or brushless motor; in this case, as specified above, the permanent magnets 3 of the chain 2 can have alternate polarity. This, as known, enables a more precise control of the position of the chain 2.

Alternatively, the electric machine can be an asynchronous electric motor, and the permanent magnets 3 of the chain 2 can have identical polarity.

The above has been described by way of non-limiting example, and any constructional variants are understood to fall within the ambit of protection of the present technical solution, as claimed in the following.