Mechanism for the opening of folding doors

Abstract

Mechanism for the opening and the closing of at least one pair of folding doors configured to be mounted on a structure (50; 100) comprising a first vertical upright (1), a second vertical upright (4) and an upper horizontal lintel (5) between the two vertical uprights (1, 4), wherein said at least one pair of folding doors consists of a first door (2; 102) hinged along one of its vertical edges to one of said vertical uprights (1, 4) to perform a rotation with vertical axis and a second door (3; 103) hinged along one of its vertical edges to the unrestrained vertical edge of the first door (2; 102) to perform a rotation with vertical axis, also comprising: - a track (6; 106) intended to be installed on said lintel (5) and extending in a direction parallel to the direction of longitudinal development of the lintel (5); - a carriage (7; 107) intended to engage slidingly with said track (6; 106) between a start of travel position and an end of travel position; - a first connecting arm (10'; 110') fixed at one of its ends to said carriage (7; 107) in a rotating manner in a fulcrum point (22; 122) and intended to be fixed, at the other end, in a rotating manner to an upper crosspiece (11; 111) of the second door (3; 103) in a fulcrum point (24; 124); - a second connecting arm (10"; 110") fixed at one of its ends to said carriage (7; 107) in a rotating manner in a fulcrum point (23; 123) and intended to be fixed, at the other end, to an upper crosspiece (11; 111) of the second door (3; 103) in a fulcrum point (25; 125); wherein said first arm (10'; 110') and said second arm (10"; 110") have the same length, such that, in operation, the two arms (10' and 10"; 110' and 110") form with the fulcrum points (22 and 23; 122 and 123) on the carriage (7; 107) and with the fulcrum points (24 and 25; 124 and 125) on the upper crosspiece (11; 111) of the second door (3; 103) a parallelogram with angles that vary during the movement of opening and closing of the pair of doors, all the fulcrum points of the arms being mobile during the movement of opening and closing of the doors.

Description

[0001] The present invention relates to a mechanism for the opening and closing of a pair of folding doors that can be applied both to furniture items and to other types of fixed structures such as doors for passage between two rooms and the like.Background of the invention

[0002] Folding door systems, sometimes also called 'accordion' or 'bi-fold' systems, allow access to the front opening of the internal compartment of an item of furniture (or of a space delimited by a structure such as a door or the like) through two or more doors (or half-doors) hinged one to the other, which are superimposed one on the other in opening, freeing up part or the whole of the internal compartment they cover.

[0003] In particular, some systems consisting of a pair of hinged doors are characterised by a "folding" movement that fully involves both doors, whereof generally a first door rotates around a fixed part or vertical upright and a second door performs a translation until it is superimposed, completely or partially, on the first.

[0004] Folding door opening systems according to the prior art are described, for example, in EP4350112A1, EP3865648A1, WO2019202377A1 and DE202015003214U1.

[0005] The systems for the opening and the closing of folding doors currently known and on the market are characterised by a very cumbersome kinematic movement of their components, generally providing one or more opening arms that connect the doors to the structure in fulcrum points that remain fixed on the structure.

[0006] Furthermore, these systems have a very rigid structure and are almost entirely intended for specific use in furniture items. This means they are not very versatile and difficult to apply to other types of structures to which folding doors could be applied.

[0007] Another problem of known folding door opening systems is represented by the fact that, in operation, they often have a non-fluid and irregular movement, characterised by jamming at the dead points of rotation, particularly when the first door hinged to the fixed vertical part is at a 90° angle.Summary of the invention

[0008] The object of the invention is to eliminate the disadvantages associated with the opening and closing mechanisms for folding doors found in currently known systems.

[0009] In particular, one object of the present invention is to provide a mechanism for the opening and the closing of a pair of folding doors capable of bringing the doors from a position of closure in which the doors are side by side and the first door is at an angle of 0°, to an open position in which the doors are one superimposed on the other and the first door is rotated through 180°, with a kinematic mechanism of reduced bulk with respect to known movement systems.

[0010] A further object is to provide a mechanism for the opening and closure of a pair of folding doors capable of ensuring fluid and effective movement throughout the entire opening and closing range, avoiding jamming due to dead points of rotation of the doors.

[0011] Yet another object of the invention is to provide a mechanism that is easy to install, versatile and can be applied to both furniture item structures and to fixed structures.

[0012] These and other objects are achieved by the mechanism according to the invention, which has the features listed in the appended independent claim 1.

[0013] Advantageous embodiments of the invention are disclosed by the dependent claims.

[0014] Substantially, the present invention relates to a mechanism for the opening and the closing of at least one pair of folding doors configured to be mounted on a structure comprising a first vertical upright, a second vertical upright and an upper horizontal lintel between the two vertical uprights, wherein said at least one pair of folding doors consists of a first door hinged along one of its vertical edges to one of said vertical uprights to perform a rotation with vertical axis and a second door hinged along one of its vertical edges to the unrestrained vertical edge of the first door to perform a rotation with vertical axis, also comprising: a track intended to be installed on said lintel and extending in a direction parallel to the direction of longitudinal development of the lintel; a carriage intended to engage slidingly with said track between a start of travel position and an end of travel position; a first connecting arm fixed at one of its ends to said carriage in a rotating manner in a fulcrum point and intended to be fixed, at the other end, in a rotating manner to an upper crosspiece of the second door in a fulcrum point; a second connecting arm fixed at one of its ends to said carriage in a rotating manner in a fulcrum point and intended to be fixed, at the other end, to an upper crosspiece of the second door in a fulcrum point; wherein said first arm and said second arm have the same length, such that, in operation, the two arms form with the fulcrum points on the carriage and with the fulcrum points on the upper crosspiece of the second door a parallelogram with angles that vary during the movement of opening and closing of the pair of doors, all the fulcrum points of the arms being mobile during the movement of opening and closing of the doors.Brief description of the drawings

[0015] Further features of the invention will be made clearer by the detailed description here below, referring to one of its embodiments purely by way of non-limiting example, illustrated in the accompanying drawings, in which: Figure 1a and Figure 1b are isometric views, from the front and from the rear respectively, of a standard structure to which a pair of folding doors are attached; Figure 2a is a schematic view, substantially corresponding to a plan view from above of the structure in Fig. 1a, in which the doors are in the condition of closure; Figures 2b, 2c, 2d, and 2e are schematic views, like that of Fig. 2a, that show different configurations of the reciprocal position of the doors during the ideal opening movement of a system of folding doors, starting from a position of partial opening to that of complete opening; Figures 3a, 3b, 3c, 3d, and 3e are isometric views of a structure comprising two pairs of folding doors and two mechanisms for the opening of folding doors arranged in a mirror fashion, showing different configurations of the reciprocal position of the doors, starting from the position of complete closure to that of complete opening; Figures 4a, 4b, 4c, 4d, and 4e are schematic plan views from above, substantially like those of Figures 2a-2e, referred to the structure comprising two separate opening mechanisms illustrated in Figures 3a-3e; Figures 5a, 5b, 5c, 5d, 5e are schematic views like those of Figures 4a-4e referred to a structure to which a single mechanism for the opening of folding doors according to the invention is applied; Figures 6a and 6b, 7a and 7b, 8a and 8b are isometric views, respectively, of a first, second and third embodiment of a synchronisation system to be associated with a pair of mechanisms according to the invention for the synchronisation of the movement of opening and closing of structures comprising two pairs of folding doors arranged in a mirror fashion. Detailed description of the invention

[0016] The present invention will be described in greater detail with reference initially to a standard structure 50, illustrated in Figures 1a and 1b, to which a pair of folding doors hinged one to the other are attached.

[0017] Such a structure, which can generally, but not exclusively, be a structure of an item of furniture, substantially comprises a first fixed vertical part or upright 1, a second fixed vertical part or upright 4 and an upper lintel 5 provided horizontally between the two vertical uprights. The vertical uprights 1, 4 can be equivalent to pillars, walls, sides of an item of furniture, and so on. These elements define, together with an end surface, which can be represented by the base of an item of furniture or the floor itself, the perimeter of a compartment.

[0018] As mentioned previously, the structure is not limited exclusively to those of furniture, but can also be represented, for example, by a door, in particular a door for passage between two spaces, delimited by two vertical uprights and by a horizontal lintel. In this case, clearly, the compartment is represented by the space (internal or external) accessed via the structure.

[0019] As illustrated in Figures 1a and 1b, the compartment is delimited in closure by a pair of folding doors. In particular, a first door 2 is hinged to the first upright 1 by means of one or more hinge elements 8, so as to rotate with vertical axis around this upright 1.

[0020] A second door 3 is hinged to the first door 2 by means of one or more hinge elements 9, so as to rotate in turn with vertical axis with respect to the vertical edge of the first door 2 not hinged to the upright 1. In the structure illustrated hitherto, provided with a pair of folding doors, the second upright 4 can act as a stop for the non-hinged vertical edge of door 2 when the doors are in a condition of complete closure.

[0021] This closure configuration is illustrated schematically in the view of Fig. 2a, which substantially corresponds to a schematic view from above of the structure 50, in which the horizontal lintel is indicated by dotted lines.

[0022] Referring to Figures 2b-2e below, what should be the ideal movement of a pair of folding doors applied to a structure 50 is described and illustrated.

[0023] Starting from the condition of complete closure of Fig. 2a, in which doors 2, 3 are arranged side by side, a user acts on a handle 12 provided on the second door, pulling it towards themselves.

[0024] The second door 3, hinged to the first door 2 and through the latter to the first vertical upright 1, will move towards the user while remaining parallel to the starting position and at the same time performing a lateral movement towards the first door 2, which in turn will perform a rotation around the first upright 1.

[0025] The movement of opening will end when the first door 2 has performed a rotation of almost 180° around the first vertical upright 1, and the two doors are substantially superimposed one on the other.

[0026] Known folding door guide systems do not allow this ideal movement to be achieved effectively, which allows the second door to be maintained always parallel and to reduce the footprint space required for the mechanism.

[0027] In particular, known opening systems are characterised by the fact that they provide a pair of arms hinged at one end to the lintel 5 of the structure and at the other end to the second door 3 of the pair of folding doors, preferably on one of its upper crosspieces, forming a parallelogram configuration whose angles vary in amplitude during the opening and closing movement.

[0028] In these known systems, the fulcrum points in which the arms are hinged to the lintel are always fixed, resulting in a cumbersome and poorly versatile mechanism, since it requires, in particular, arms of considerable length.

[0029] Furthermore, one of the problems often found in known systems consists of the fact of finding greater resistance during the operation of opening and of closing due to the doors jamming in dead points, as in the position illustrated in Fig. 2c, in which the first door is substantially at a 90° angle.

[0030] A mechanism of movement of doors according to the present invention allows a fluid and efficient movement to be obtained throughout the entire arc of opening and differs from those currently known due to the presence of a novel mechanical-kinematic system for making the second door slide always in a parallel manner.

[0031] This mechanism can also be applied, without any limitation, to structures that provide two pairs of doors with opposite opening, like the structure illustrated in Figures 3a, 3b, 3c, 3d, and 3e. Advantageously, the mechanism can allow the pairs of doors to open and close simultaneously in a mirror manner.

[0032] Figures 3a-3e show a structure 100 formed by a first vertical upright 1, a second vertical upright 4 and a crosspiece or lintel 5. The space defined by these elements is accessible via two pairs of doors arranged in a mirror manner.

[0033] A first pair of doors is formed by a first door 2, hinged to the upright 1 by means of one or more hinge elements 8, to perform a rotation with vertical axis, and a second door 3, hinged in turn to the first door 2 by means of appropriate hinges 9, to perform a rotation around a vertical axis.

[0034] A second pair is formed by a first door 102 hinged to a second upright 4 by means of appropriate hinges 108, to perform a rotation around a vertical axis defined substantially by the upright 4, and a second door 103 in turn hinged to the first door 102, similarly to what is described for the previous pair of doors.

[0035] In the closed condition, illustrated in Fig. 3a, the doors of the two pairs are parallel and side by side, completely closing the compartment of the structure.

[0036] The mechanism for opening folding doors according to the invention is characterised in that it provides a track intended to be applied in the upper part of the compartment, in particular at the upper part or inside the lintel 5. Figures 3a-3e show two tracks 6 and 106 that develop in a parallel direction to the longitudinal direction of the lintel 5, for the movement of the pairs of doors 2, 3 and 102, 103, respectively.

[0037] Two sliding carriages 7, 107 are engaged slidingly with the tracks 6, 106. Given that the mechanism used for the first pair of doors is similar and arranged in a mirror manner to that used for the second pair of doors, the components of the mechanism according to the invention will be described in detail with reference to the part of the structure corresponding to the first pair of doors 2 and 3, it being understood that similar components will have similar configurations and functioning, such as, for example, the sliding carriages 7 and 107, the tracks 6 and 106, and so on.

[0038] Two horizontal arms 10', 10" of equal length are fixed in a rotatable manner to the carriage 7, with one end of the first arm 10' hinged to the carriage 7 in a fulcrum point 22 and one end of the second arm 10" hinged to the carriage in the fulcrum point 23. The fulcrum points 22, 23 are arranged on an ideal horizontal line parallel to the track 6 on which the carriage 7 slides.

[0039] The other ends of arms 10', 10" are instead intended to be fixed in a rotatable manner to the upper crosspiece 11 of the second door 3 in fulcrum points 24, 25. The distance between fulcrum points 22, 23 on carriage 7 and between fulcrum points 24, 25 on crosspiece 11 of door 3 is equal. Consequently, fulcrum points 22, 23, 24, 25 define the vertices of a parallelogram.

[0040] Preferably, fulcrum point 25 is provided on crosspiece 11 at the free end of door 3.

[0041] With a mechanism having this configuration, it is possible to achieve the ideal opening movement described above and schematised in Figures 4a, 4b, 4c, 4d, 4e with reference to structure 100, which provides two pairs of folding doors. This movement is also shown in simplified form in Figures 5a, 5b, 5c, 5d, 5e, which are referred to a structure with a single pair of folding doors.

[0042] In the condition of complete closure illustrated in Figure 3a and schematised in Figures 4a and 5a, doors 2, 3 of the pair of folding doors are arranged side by side to completely cover the compartment. In this condition, the carriage 7 is in a starting position, at an end point of the track arranged in proximity of the first vertical upright 1. Advantageously, in this end, the track can be configured to provide a retaining element 15 for the sliding of the carriage 7.

[0043] Starting from this position, by acting in opening on a handle 12 on the second door 3, i.e. 'pulling it towards the outside', there is a movement of the door 3, which in turn causes an initial movement of the carriage 7, to which it is connected via the arms 10', 10".

[0044] Since carriage 7 is constrained to slide along horizontal track 6, thanks to the particular configuration of the mobile fulcrum points 22, 23, 24, 25 and to the length of arms 10', 10", the second door 3 will move laterally, always remaining parallel to the starting position.

[0045] In practice, throughout the movement of opening / closing, the mechanism defined by the arms 10', 10" and by the fulcrum points 22, 23, 24, 25 always maintains a parallelogram configuration, characterised in that not only are the angles defined by the pair of parallel arms and by the fulcrum points always variable during the phases of opening and closing, but also in that, during the movement, all the fulcrum points in which the arms are fixed are always in different positions.

[0046] The movement of the second door 3 obviously causes the rotation of the first door 2, to which it is hinged. The sliding of the carriage 7 in the track 6 governs the movement of opening and closing and the reciprocal position of the doors, which at a certain point will go into the condition illustrated in Figures 3c, 4c, 5c, in which the arms are substantially orthogonal to the crosspiece 11 of door 3, which in turn is substantially perpendicular to door 2.

[0047] In this position, there is a sort of dead point of the movement of rotation, since the first door 2 reaches an angle of 90°. If door 3 were to be pulled further outwards with a force directed substantially in a perpendicular direction to the door itself, as necessary for initiating the movement of opening, there would be no rotation arm for door 2. It is therefore normally necessary to change the direction of application of the opening force to complete the operation. The same applies, naturally, to the movement of closing.

[0048] In order to overcome this disadvantage, the mechanism according to the invention can advantageously provide rotation guides fixed to the lintel, intended to facilitate the movement of the arms during rotation, helping to overcome the dead point position.

[0049] Illustrated in the embodiments shown in the drawings, for each mechanism, are two rotation guides 14', 14" associated respectively with the arms 10', 10", even if it is possible to provide a single rotation guide associated with a single arm.

[0050] The rotation guides 14', 14" have a configuration such as to provide a curved guide surface turned towards track 6 to accommodate respective guide rollers 13', 13" associated with arms 10', 10".

[0051] The arrangement of the guides on the lintel 5 is such that they do not overlap the movement of the arms 10', 10", which pass over them, and only interfere with the pulleys.

[0052] In particular, the pulleys 13', 13" are provided in the lower part of the arms 10', 10" in a position such that they interfere with the orientation guides 14', 14" before reaching the dead point, such as for example, in opening, in the position shown in Figures 3b, 4b, 5b.

[0053] When they interfere with the guides 14', 14", the pulleys begin to traverse the curved guide surface provided in them, which has a substantially undulating convex profile. The pulleys thus enter a peak point, travel along the profile to a down point, and rise by inertia towards a peak point provided at the exit.

[0054] The presence of guides provided with curved guide surfaces intended to accommodate pulleys provided on arms 10', 10', means that the opening force transmitted via the handle 12 of door 3 is directed in such a way as to avoid the jamming that would occur in the position shown in Figures 3c, 4c, and 5c, in which the arms are in a substantially orthogonal direction, making the rotation of the door 2 fluid and effective throughout the movement of opening and closing.

[0055] At the end of the movement of opening, the doors will be one over the other as in the illustrations of Figures 3e, 4e, 5e, with door 2 which will have completed a rotation of almost 180° around upright 1. In this condition, carriage 7 has reached the end position, being located in the end point of track 6 opposite upright 1.

[0056] Clearly, a mirror movement occurs during the closing of the door, starting from the position of Fig. 3e up to that of Fig. 3a. Advantageously, if provided, the rotation guides facilitate the rotation of the door also in closure.

[0057] Figures 3a-3e show a carriage that has a substantially elongated shape in the direction of development of the track, occupying most of the latter. Clearly, this configuration is purely illustrative, and many other carriage shapes can be provided that are capable of performing the functions illustrated above.

[0058] Furthermore, in the embodiments illustrated, the carriage 7, 107 has, at its end opposite the respective upright of rotation of door 2, 102, a portion 7', 107' such as to engage a further guide rod 19, 119. In these drawings, the guide rods 19, 119 protrude from a support element 30 provided on the centre line of the lintel 5 of the structure with two pairs of doors.

[0059] Advantageously, the centre line support element 30 has respective stop surfaces on which act deceleration devices 21, 121 in the form of dampers or piston shock absorbers arranged on the end portions 7', 107' of the carriages 7, 107, which allow the travel of the carriage to be slowed down gradually and the movement of the doors during opening to be dampened, particularly when the opening reaches approximately 180°, preventing the first door 2, 102 from stopping its rotation too abruptly.

[0060] Similarly, at the other end of the carriage 7, 107 turned towards the upright 1, 4, a deceleration device or shock absorber 17, 117 is provided, configured to abut against a surface of the retaining element 15, 115 of the track 6, 106, to slow down the movement of the doors in closure, thus avoiding sudden closures and the doors banging against the lintel 5.

[0061] In addition to those described, other types of systems of deceleration and of shock absorbing of the movement of opening and closing of the doors are possible, all within the scope of the person skilled in the art.

[0062] Although the mechanism of opening according to the invention has been described in detail with reference to a structure 100 with two pairs of folding doors, it will be understood that it can also be applied in the same way to structures which provide only one pair of doors, such as that shown in Figures 1a and 1b, maintaining all the features and functions described above.

[0063] In particular, it will be understood that the second vertical upright 4 can perform both the function of stop for the second door 3 in the case of structures with a pair of folding doors, and the function of support structure for the hinges 108 of the first door 102 of the second pair of doors, in the case of structures with two pairs of folding doors.

[0064] Furthermore, in the case of structures with only one pair of folding doors, there will be no centre line support element 30 such as that illustrated in Figures 3a-3e, but instead a support element placed at the second vertical upright 4, this support element being able to perform the same functions described above, including those of support of a guide door for the end of the carriage and stop surface for a shock absorber actuated during the movement of opening.

[0065] The mechanism according to the invention, when applied in a mirror manner on the same lintel 5 of a structure 100 with two pairs of folding doors 2 and 3, 102 and 103 as in the structure illustrated in Figures 3a-3e, also advantageously allows a simultaneous opposite movement of the two pairs of doors in opening and closing to be obtained, connecting the respective sliding carriages 7, 107 with a kinematic mechanism.

[0066] This kinematic mechanism allows the two sliding carriages to be connected to generate a linear opposing movement of the same. The kinematic connection between the two carriages can take place in different ways.

[0067] A first way provides for a cable or a belt closed in a loop and tensioned, which is wound on two pulleys. An example of a synchronisation system based on this functioning is illustrated in Figures 6a and 6b, in which two carriages 7, 107 are shown, engaged in respective tracks 6, 106 of two opening mechanisms according to the invention, arranged in a mirror manner one next to the other. The two tracks 6, 106 can be joined, for example at the centre line support element 30.

[0068] Two pulleys, or sheaves, 32, 132 are arranged at the ends of the tracks, preferably at the retaining elements 15, 115, protruding towards the doors. A cable or belt 31 is wrapped around the pulleys in a loop, to which end portions 7', 107' of the carriages 7, 107 are fixed in an immovable manner.

[0069] The end portions 7', 107' are configured in such a way as to be fixed to the cable 32, when the latter is applied to the pulley, on opposite sections of the cable itself, as illustrated in Fig. 6a, in which the carriages are practically in the condition of end of travel.

[0070] By rotating the cable around the pulleys, the two points of fixing of the sliding carriages will move away or move closer according to the direction of rotation of the cable. By imposing, for example, a counterclockwise rotation on the cable (i.e., starting a movement of closure), the carriages, moving with the cable via the ends 107' 107 to which they are fixed, will move synchronously until reaching the position of Fig. 6b.

[0071] Another mode of synchronisation of the movement provides for the two carriages to be fixed to respective rack rods, which go to engage with a pinion provided in the centre of the lintel 5 on which the tracks 6, 106 of the opening mechanisms are mounted.

[0072] An embodiment of such a synchronisation system is illustrated in Figures 7a and 7b, in which the reference numerals are unchanged with respect to the embodiment described above.

[0073] According to this embodiment, a pinion 50 is arranged at the centre line support element 30, oriented towards the doors. The two carriages 7, 107 carry at their end portions 7', 107' respective rack rods 52, 152, with the teeth of the racks of the two rods turned towards each other.

[0074] Thanks to the interaction with the pinion, by making one of the two carriages slide in the track, the other one will move in the opposite direction to the first. By adjusting the reciprocal position of the carriages on the tracks, the synchronous sliding movement illustrated in Figures 7a and 7b will be achieved.

[0075] Another method provides for the attaching of a nut engaged with a worm screw to each of the two sliding carriages, as in the embodiments shown in Figures 8a and 8b.

[0076] Two nuts are fixed to the respective sliding carriages 7, 107, advantageously at the ends 7', 107'. The nuts have opposite rotation principles and are engaged in a worm screw 60. The worm screw 60 is formed by two sections with rotation principles opposite and complementary to those of the respective nuts and is held in position by a stop fixed to the lintel, for example in the centre line support element 30. In this way, the worm screw can rotate freely in the two directions, but the stop prevents it from moving parallel to the track.

[0077] With such an arrangement, by appropriately synchronising the position of the nuts, the movement of a carriage in one direction will correspond to an identical movement but in the opposite direction.

[0078] Clearly, other systems for synchronisation of the movement of the carriages on the respective tracks can be provided within the reach of a person skilled in the art.

[0079] It is also possible to insert an electric actuator, for structures with one or two pairs of doors, thus making the closing / opening movement electrifiable.

[0080] From what is disclosed above, the advantages of the mechanism for folding doors according to the invention are clear, which has a versatile structure, with reduced overall dimensions, and allows a fluid movement of the doors over an arc substantially of 180°, both in opening and closing.

[0081] In particular, the mechanism of opening for folding doors illustrated here enables all currently known systems to be surpassed thanks to a kinematic mechanism consisting of a pair of horizontal arms, which, together with the upper crosspiece of the second door of the pair of folding doors and a carriage sliding in a track arranged on the lintel of the structure, form a parallelogram with angles that vary during the movement of opening-closing of the system.

[0082] Such a configuration allows in an innovative manner to provide fulcrum points of the connecting arms which are mobile throughout the movement of opening and closing, generally reducing the overall dimensions due to the kinematics of the elements of the mechanism with respect to systems currently in use, particularly the depth dimensions.

[0083] Naturally the invention is not limited to the particular embodiment previously described and illustrated in the accompanying drawings, but numerous detailed changes may be made thereto within the reach of the person skilled in the art, without thereby departing from the scope of the invention as defined in the appended claims.

Examples

Embodiment Construction

[0016]The present invention will be described in greater detail with reference initially to a standard structure 50, illustrated in Figures 1a and 1b, to which a pair of folding doors hinged one to the other are attached.

[0017]Such a structure, which can generally, but not exclusively, be a structure of an item of furniture, substantially comprises a first fixed vertical part or upright 1, a second fixed vertical part or upright 4 and an upper lintel 5 provided horizontally between the two vertical uprights. The vertical uprights 1, 4 can be equivalent to pillars, walls, sides of an item of furniture, and so on. These elements define, together with an end surface, which can be represented by the base of an item of furniture or the floor itself, the perimeter of a compartment.

[0018]As mentioned previously, the structure is not limited exclusively to those of furniture, but can also be represented, for example, by a door, in particular a door for passage between two spaces, delimited ...

[0001] The present invention relates to a mechanism for the opening and closing of a pair of folding doors that can be applied both to furniture items and to other types of fixed structures such as doors for passage between two rooms and the like.Background of the invention

[0002] Folding door systems, sometimes also called 'accordion' or 'bi-fold' systems, allow access to the front opening of the internal compartment of an item of furniture (or of a space delimited by a structure such as a door or the like) through two or more doors (or half-doors) hinged one to the other, which are superimposed one on the other in opening, freeing up part or the whole of the internal compartment they cover.

[0003] In particular, some systems consisting of a pair of hinged doors are characterised by a "folding" movement that fully involves both doors, whereof generally a first door rotates around a fixed part or vertical upright and a second door performs a translation until it is superimposed, completely or partially, on the first.

[0004] Folding door opening systems according to the prior art are described, for example, in EP4350112A1, EP3865648A1, WO2019202377A1 and DE202015003214U1.

[0005] The systems for the opening and the closing of folding doors currently known and on the market are characterised by a very cumbersome kinematic movement of their components, generally providing one or more opening arms that connect the doors to the structure in fulcrum points that remain fixed on the structure.

[0006] Furthermore, these systems have a very rigid structure and are almost entirely intended for specific use in furniture items. This means they are not very versatile and difficult to apply to other types of structures to which folding doors could be applied.

[0007] Another problem of known folding door opening systems is represented by the fact that, in operation, they often have a non-fluid and irregular movement, characterised by jamming at the dead points of rotation, particularly when the first door hinged to the fixed vertical part is at a 90° angle.Summary of the invention

[0008] The object of the invention is to eliminate the disadvantages associated with the opening and closing mechanisms for folding doors found in currently known systems.

[0009] In particular, one object of the present invention is to provide a mechanism for the opening and the closing of a pair of folding doors capable of bringing the doors from a position of closure in which the doors are side by side and the first door is at an angle of 0°, to an open position in which the doors are one superimposed on the other and the first door is rotated through 180°, with a kinematic mechanism of reduced bulk with respect to known movement systems.

[0010] A further object is to provide a mechanism for the opening and closure of a pair of folding doors capable of ensuring fluid and effective movement throughout the entire opening and closing range, avoiding jamming due to dead points of rotation of the doors.

[0011] Yet another object of the invention is to provide a mechanism that is easy to install, versatile and can be applied to both furniture item structures and to fixed structures.

[0012] These and other objects are achieved by the mechanism according to the invention, which has the features listed in the appended independent claim 1.

[0013] Advantageous embodiments of the invention are disclosed by the dependent claims.

[0014] Substantially, the present invention relates to a mechanism for the opening and the closing of at least one pair of folding doors configured to be mounted on a structure comprising a first vertical upright, a second vertical upright and an upper horizontal lintel between the two vertical uprights, wherein said at least one pair of folding doors consists of a first door hinged along one of its vertical edges to one of said vertical uprights to perform a rotation with vertical axis and a second door hinged along one of its vertical edges to the unrestrained vertical edge of the first door to perform a rotation with vertical axis, also comprising: a track intended to be installed on said lintel and extending in a direction parallel to the direction of longitudinal development of the lintel; a carriage intended to engage slidingly with said track between a start of travel position and an end of travel position; a first connecting arm fixed at one of its ends to said carriage in a rotating manner in a fulcrum point and intended to be fixed, at the other end, in a rotating manner to an upper crosspiece of the second door in a fulcrum point; a second connecting arm fixed at one of its ends to said carriage in a rotating manner in a fulcrum point and intended to be fixed, at the other end, to an upper crosspiece of the second door in a fulcrum point; wherein said first arm and said second arm have the same length, such that, in operation, the two arms form with the fulcrum points on the carriage and with the fulcrum points on the upper crosspiece of the second door a parallelogram with angles that vary during the movement of opening and closing of the pair of doors, all the fulcrum points of the arms being mobile during the movement of opening and closing of the doors.Brief description of the drawings

[0015] Further features of the invention will be made clearer by the detailed description here below, referring to one of its embodiments purely by way of non-limiting example, illustrated in the accompanying drawings, in which: Figure 1a and Figure 1b are isometric views, from the front and from the rear respectively, of a standard structure to which a pair of folding doors are attached; Figure 2a is a schematic view, substantially corresponding to a plan view from above of the structure in Fig. 1a, in which the doors are in the condition of closure; Figures 2b, 2c, 2d, and 2e are schematic views, like that of Fig. 2a, that show different configurations of the reciprocal position of the doors during the ideal opening movement of a system of folding doors, starting from a position of partial opening to that of complete opening; Figures 3a, 3b, 3c, 3d, and 3e are isometric views of a structure comprising two pairs of folding doors and two mechanisms for the opening of folding doors arranged in a mirror fashion, showing different configurations of the reciprocal position of the doors, starting from the position of complete closure to that of complete opening; Figures 4a, 4b, 4c, 4d, and 4e are schematic plan views from above, substantially like those of Figures 2a-2e, referred to the structure comprising two separate opening mechanisms illustrated in Figures 3a-3e; Figures 5a, 5b, 5c, 5d, 5e are schematic views like those of Figures 4a-4e referred to a structure to which a single mechanism for the opening of folding doors according to the invention is applied; Figures 6a and 6b, 7a and 7b, 8a and 8b are isometric views, respectively, of a first, second and third embodiment of a synchronisation system to be associated with a pair of mechanisms according to the invention for the synchronisation of the movement of opening and closing of structures comprising two pairs of folding doors arranged in a mirror fashion. Detailed description of the invention

[0016] The present invention will be described in greater detail with reference initially to a standard structure 50, illustrated in Figures 1a and 1b, to which a pair of folding doors hinged one to the other are attached.

[0017] Such a structure, which can generally, but not exclusively, be a structure of an item of furniture, substantially comprises a first fixed vertical part or upright 1, a second fixed vertical part or upright 4 and an upper lintel 5 provided horizontally between the two vertical uprights. The vertical uprights 1, 4 can be equivalent to pillars, walls, sides of an item of furniture, and so on. These elements define, together with an end surface, which can be represented by the base of an item of furniture or the floor itself, the perimeter of a compartment.

[0018] As mentioned previously, the structure is not limited exclusively to those of furniture, but can also be represented, for example, by a door, in particular a door for passage between two spaces, delimited by two vertical uprights and by a horizontal lintel. In this case, clearly, the compartment is represented by the space (internal or external) accessed via the structure.

[0019] As illustrated in Figures 1a and 1b, the compartment is delimited in closure by a pair of folding doors. In particular, a first door 2 is hinged to the first upright 1 by means of one or more hinge elements 8, so as to rotate with vertical axis around this upright 1.

[0020] A second door 3 is hinged to the first door 2 by means of one or more hinge elements 9, so as to rotate in turn with vertical axis with respect to the vertical edge of the first door 2 not hinged to the upright 1. In the structure illustrated hitherto, provided with a pair of folding doors, the second upright 4 can act as a stop for the non-hinged vertical edge of door 2 when the doors are in a condition of complete closure.

[0021] This closure configuration is illustrated schematically in the view of Fig. 2a, which substantially corresponds to a schematic view from above of the structure 50, in which the horizontal lintel is indicated by dotted lines.

[0022] Referring to Figures 2b-2e below, what should be the ideal movement of a pair of folding doors applied to a structure 50 is described and illustrated.

[0023] Starting from the condition of complete closure of Fig. 2a, in which doors 2, 3 are arranged side by side, a user acts on a handle 12 provided on the second door, pulling it towards themselves.

[0024] The second door 3, hinged to the first door 2 and through the latter to the first vertical upright 1, will move towards the user while remaining parallel to the starting position and at the same time performing a lateral movement towards the first door 2, which in turn will perform a rotation around the first upright 1.

[0025] The movement of opening will end when the first door 2 has performed a rotation of almost 180° around the first vertical upright 1, and the two doors are substantially superimposed one on the other.

[0026] Known folding door guide systems do not allow this ideal movement to be achieved effectively, which allows the second door to be maintained always parallel and to reduce the footprint space required for the mechanism.

[0027] In particular, known opening systems are characterised by the fact that they provide a pair of arms hinged at one end to the lintel 5 of the structure and at the other end to the second door 3 of the pair of folding doors, preferably on one of its upper crosspieces, forming a parallelogram configuration whose angles vary in amplitude during the opening and closing movement.

[0028] In these known systems, the fulcrum points in which the arms are hinged to the lintel are always fixed, resulting in a cumbersome and poorly versatile mechanism, since it requires, in particular, arms of considerable length.

[0029] Furthermore, one of the problems often found in known systems consists of the fact of finding greater resistance during the operation of opening and of closing due to the doors jamming in dead points, as in the position illustrated in Fig. 2c, in which the first door is substantially at a 90° angle.

[0030] A mechanism of movement of doors according to the present invention allows a fluid and efficient movement to be obtained throughout the entire arc of opening and differs from those currently known due to the presence of a novel mechanical-kinematic system for making the second door slide always in a parallel manner.

[0031] This mechanism can also be applied, without any limitation, to structures that provide two pairs of doors with opposite opening, like the structure illustrated in Figures 3a, 3b, 3c, 3d, and 3e. Advantageously, the mechanism can allow the pairs of doors to open and close simultaneously in a mirror manner.

[0032] Figures 3a-3e show a structure 100 formed by a first vertical upright 1, a second vertical upright 4 and a crosspiece or lintel 5. The space defined by these elements is accessible via two pairs of doors arranged in a mirror manner.

[0033] A first pair of doors is formed by a first door 2, hinged to the upright 1 by means of one or more hinge elements 8, to perform a rotation with vertical axis, and a second door 3, hinged in turn to the first door 2 by means of appropriate hinges 9, to perform a rotation around a vertical axis.

[0034] A second pair is formed by a first door 102 hinged to a second upright 4 by means of appropriate hinges 108, to perform a rotation around a vertical axis defined substantially by the upright 4, and a second door 103 in turn hinged to the first door 102, similarly to what is described for the previous pair of doors.

[0035] In the closed condition, illustrated in Fig. 3a, the doors of the two pairs are parallel and side by side, completely closing the compartment of the structure.

[0036] The mechanism for opening folding doors according to the invention is characterised in that it provides a track intended to be applied in the upper part of the compartment, in particular at the upper part or inside the lintel 5. Figures 3a-3e show two tracks 6 and 106 that develop in a parallel direction to the longitudinal direction of the lintel 5, for the movement of the pairs of doors 2, 3 and 102, 103, respectively.

[0037] Two sliding carriages 7, 107 are engaged slidingly with the tracks 6, 106. Given that the mechanism used for the first pair of doors is similar and arranged in a mirror manner to that used for the second pair of doors, the components of the mechanism according to the invention will be described in detail with reference to the part of the structure corresponding to the first pair of doors 2 and 3, it being understood that similar components will have similar configurations and functioning, such as, for example, the sliding carriages 7 and 107, the tracks 6 and 106, and so on.

[0038] Two horizontal arms 10', 10" of equal length are fixed in a rotatable manner to the carriage 7, with one end of the first arm 10' hinged to the carriage 7 in a fulcrum point 22 and one end of the second arm 10" hinged to the carriage in the fulcrum point 23. The fulcrum points 22, 23 are arranged on an ideal horizontal line parallel to the track 6 on which the carriage 7 slides.

[0039] The other ends of arms 10', 10" are instead intended to be fixed in a rotatable manner to the upper crosspiece 11 of the second door 3 in fulcrum points 24, 25. The distance between fulcrum points 22, 23 on carriage 7 and between fulcrum points 24, 25 on crosspiece 11 of door 3 is equal. Consequently, fulcrum points 22, 23, 24, 25 define the vertices of a parallelogram.

[0040] Preferably, fulcrum point 25 is provided on crosspiece 11 at the free end of door 3.

[0041] With a mechanism having this configuration, it is possible to achieve the ideal opening movement described above and schematised in Figures 4a, 4b, 4c, 4d, 4e with reference to structure 100, which provides two pairs of folding doors. This movement is also shown in simplified form in Figures 5a, 5b, 5c, 5d, 5e, which are referred to a structure with a single pair of folding doors.

[0042] In the condition of complete closure illustrated in Figure 3a and schematised in Figures 4a and 5a, doors 2, 3 of the pair of folding doors are arranged side by side to completely cover the compartment. In this condition, the carriage 7 is in a starting position, at an end point of the track arranged in proximity of the first vertical upright 1. Advantageously, in this end, the track can be configured to provide a retaining element 15 for the sliding of the carriage 7.

[0043] Starting from this position, by acting in opening on a handle 12 on the second door 3, i.e. 'pulling it towards the outside', there is a movement of the door 3, which in turn causes an initial movement of the carriage 7, to which it is connected via the arms 10', 10".

[0044] Since carriage 7 is constrained to slide along horizontal track 6, thanks to the particular configuration of the mobile fulcrum points 22, 23, 24, 25 and to the length of arms 10', 10", the second door 3 will move laterally, always remaining parallel to the starting position.

[0045] In practice, throughout the movement of opening / closing, the mechanism defined by the arms 10', 10" and by the fulcrum points 22, 23, 24, 25 always maintains a parallelogram configuration, characterised in that not only are the angles defined by the pair of parallel arms and by the fulcrum points always variable during the phases of opening and closing, but also in that, during the movement, all the fulcrum points in which the arms are fixed are always in different positions.

[0046] The movement of the second door 3 obviously causes the rotation of the first door 2, to which it is hinged. The sliding of the carriage 7 in the track 6 governs the movement of opening and closing and the reciprocal position of the doors, which at a certain point will go into the condition illustrated in Figures 3c, 4c, 5c, in which the arms are substantially orthogonal to the crosspiece 11 of door 3, which in turn is substantially perpendicular to door 2.

[0047] In this position, there is a sort of dead point of the movement of rotation, since the first door 2 reaches an angle of 90°. If door 3 were to be pulled further outwards with a force directed substantially in a perpendicular direction to the door itself, as necessary for initiating the movement of opening, there would be no rotation arm for door 2. It is therefore normally necessary to change the direction of application of the opening force to complete the operation. The same applies, naturally, to the movement of closing.

[0048] In order to overcome this disadvantage, the mechanism according to the invention can advantageously provide rotation guides fixed to the lintel, intended to facilitate the movement of the arms during rotation, helping to overcome the dead point position.

[0049] Illustrated in the embodiments shown in the drawings, for each mechanism, are two rotation guides 14', 14" associated respectively with the arms 10', 10", even if it is possible to provide a single rotation guide associated with a single arm.

[0050] The rotation guides 14', 14" have a configuration such as to provide a curved guide surface turned towards track 6 to accommodate respective guide rollers 13', 13" associated with arms 10', 10".

[0051] The arrangement of the guides on the lintel 5 is such that they do not overlap the movement of the arms 10', 10", which pass over them, and only interfere with the pulleys.

[0052] In particular, the pulleys 13', 13" are provided in the lower part of the arms 10', 10" in a position such that they interfere with the orientation guides 14', 14" before reaching the dead point, such as for example, in opening, in the position shown in Figures 3b, 4b, 5b.

[0053] When they interfere with the guides 14', 14", the pulleys begin to traverse the curved guide surface provided in them, which has a substantially undulating convex profile. The pulleys thus enter a peak point, travel along the profile to a down point, and rise by inertia towards a peak point provided at the exit.

[0054] The presence of guides provided with curved guide surfaces intended to accommodate pulleys provided on arms 10', 10', means that the opening force transmitted via the handle 12 of door 3 is directed in such a way as to avoid the jamming that would occur in the position shown in Figures 3c, 4c, and 5c, in which the arms are in a substantially orthogonal direction, making the rotation of the door 2 fluid and effective throughout the movement of opening and closing.

[0055] At the end of the movement of opening, the doors will be one over the other as in the illustrations of Figures 3e, 4e, 5e, with door 2 which will have completed a rotation of almost 180° around upright 1. In this condition, carriage 7 has reached the end position, being located in the end point of track 6 opposite upright 1.

[0056] Clearly, a mirror movement occurs during the closing of the door, starting from the position of Fig. 3e up to that of Fig. 3a. Advantageously, if provided, the rotation guides facilitate the rotation of the door also in closure.

[0057] Figures 3a-3e show a carriage that has a substantially elongated shape in the direction of development of the track, occupying most of the latter. Clearly, this configuration is purely illustrative, and many other carriage shapes can be provided that are capable of performing the functions illustrated above.

[0058] Furthermore, in the embodiments illustrated, the carriage 7, 107 has, at its end opposite the respective upright of rotation of door 2, 102, a portion 7', 107' such as to engage a further guide rod 19, 119. In these drawings, the guide rods 19, 119 protrude from a support element 30 provided on the centre line of the lintel 5 of the structure with two pairs of doors.

[0059] Advantageously, the centre line support element 30 has respective stop surfaces on which act deceleration devices 21, 121 in the form of dampers or piston shock absorbers arranged on the end portions 7', 107' of the carriages 7, 107, which allow the travel of the carriage to be slowed down gradually and the movement of the doors during opening to be dampened, particularly when the opening reaches approximately 180°, preventing the first door 2, 102 from stopping its rotation too abruptly.

[0060] Similarly, at the other end of the carriage 7, 107 turned towards the upright 1, 4, a deceleration device or shock absorber 17, 117 is provided, configured to abut against a surface of the retaining element 15, 115 of the track 6, 106, to slow down the movement of the doors in closure, thus avoiding sudden closures and the doors banging against the lintel 5.

[0061] In addition to those described, other types of systems of deceleration and of shock absorbing of the movement of opening and closing of the doors are possible, all within the scope of the person skilled in the art.

[0062] Although the mechanism of opening according to the invention has been described in detail with reference to a structure 100 with two pairs of folding doors, it will be understood that it can also be applied in the same way to structures which provide only one pair of doors, such as that shown in Figures 1a and 1b, maintaining all the features and functions described above.

[0063] In particular, it will be understood that the second vertical upright 4 can perform both the function of stop for the second door 3 in the case of structures with a pair of folding doors, and the function of support structure for the hinges 108 of the first door 102 of the second pair of doors, in the case of structures with two pairs of folding doors.

[0064] Furthermore, in the case of structures with only one pair of folding doors, there will be no centre line support element 30 such as that illustrated in Figures 3a-3e, but instead a support element placed at the second vertical upright 4, this support element being able to perform the same functions described above, including those of support of a guide door for the end of the carriage and stop surface for a shock absorber actuated during the movement of opening.

[0065] The mechanism according to the invention, when applied in a mirror manner on the same lintel 5 of a structure 100 with two pairs of folding doors 2 and 3, 102 and 103 as in the structure illustrated in Figures 3a-3e, also advantageously allows a simultaneous opposite movement of the two pairs of doors in opening and closing to be obtained, connecting the respective sliding carriages 7, 107 with a kinematic mechanism.

[0066] This kinematic mechanism allows the two sliding carriages to be connected to generate a linear opposing movement of the same. The kinematic connection between the two carriages can take place in different ways.

[0067] A first way provides for a cable or a belt closed in a loop and tensioned, which is wound on two pulleys. An example of a synchronisation system based on this functioning is illustrated in Figures 6a and 6b, in which two carriages 7, 107 are shown, engaged in respective tracks 6, 106 of two opening mechanisms according to the invention, arranged in a mirror manner one next to the other. The two tracks 6, 106 can be joined, for example at the centre line support element 30.

[0068] Two pulleys, or sheaves, 32, 132 are arranged at the ends of the tracks, preferably at the retaining elements 15, 115, protruding towards the doors. A cable or belt 31 is wrapped around the pulleys in a loop, to which end portions 7', 107' of the carriages 7, 107 are fixed in an immovable manner.

[0069] The end portions 7', 107' are configured in such a way as to be fixed to the cable 32, when the latter is applied to the pulley, on opposite sections of the cable itself, as illustrated in Fig. 6a, in which the carriages are practically in the condition of end of travel.

[0070] By rotating the cable around the pulleys, the two points of fixing of the sliding carriages will move away or move closer according to the direction of rotation of the cable. By imposing, for example, a counterclockwise rotation on the cable (i.e., starting a movement of closure), the carriages, moving with the cable via the ends 107' 107 to which they are fixed, will move synchronously until reaching the position of Fig. 6b.

[0071] Another mode of synchronisation of the movement provides for the two carriages to be fixed to respective rack rods, which go to engage with a pinion provided in the centre of the lintel 5 on which the tracks 6, 106 of the opening mechanisms are mounted.

[0072] An embodiment of such a synchronisation system is illustrated in Figures 7a and 7b, in which the reference numerals are unchanged with respect to the embodiment described above.

[0073] According to this embodiment, a pinion 50 is arranged at the centre line support element 30, oriented towards the doors. The two carriages 7, 107 carry at their end portions 7', 107' respective rack rods 52, 152, with the teeth of the racks of the two rods turned towards each other.

[0074] Thanks to the interaction with the pinion, by making one of the two carriages slide in the track, the other one will move in the opposite direction to the first. By adjusting the reciprocal position of the carriages on the tracks, the synchronous sliding movement illustrated in Figures 7a and 7b will be achieved.

[0075] Another method provides for the attaching of a nut engaged with a worm screw to each of the two sliding carriages, as in the embodiments shown in Figures 8a and 8b.

[0076] Two nuts are fixed to the respective sliding carriages 7, 107, advantageously at the ends 7', 107'. The nuts have opposite rotation principles and are engaged in a worm screw 60. The worm screw 60 is formed by two sections with rotation principles opposite and complementary to those of the respective nuts and is held in position by a stop fixed to the lintel, for example in the centre line support element 30. In this way, the worm screw can rotate freely in the two directions, but the stop prevents it from moving parallel to the track.

[0077] With such an arrangement, by appropriately synchronising the position of the nuts, the movement of a carriage in one direction will correspond to an identical movement but in the opposite direction.

[0078] Clearly, other systems for synchronisation of the movement of the carriages on the respective tracks can be provided within the reach of a person skilled in the art.

[0079] It is also possible to insert an electric actuator, for structures with one or two pairs of doors, thus making the closing / opening movement electrifiable.

[0080] From what is disclosed above, the advantages of the mechanism for folding doors according to the invention are clear, which has a versatile structure, with reduced overall dimensions, and allows a fluid movement of the doors over an arc substantially of 180°, both in opening and closing.

[0081] In particular, the mechanism of opening for folding doors illustrated here enables all currently known systems to be surpassed thanks to a kinematic mechanism consisting of a pair of horizontal arms, which, together with the upper crosspiece of the second door of the pair of folding doors and a carriage sliding in a track arranged on the lintel of the structure, form a parallelogram with angles that vary during the movement of opening-closing of the system.

[0082] Such a configuration allows in an innovative manner to provide fulcrum points of the connecting arms which are mobile throughout the movement of opening and closing, generally reducing the overall dimensions due to the kinematics of the elements of the mechanism with respect to systems currently in use, particularly the depth dimensions.

[0083] Naturally the invention is not limited to the particular embodiment previously described and illustrated in the accompanying drawings, but numerous detailed changes may be made thereto within the reach of the person skilled in the art, without thereby departing from the scope of the invention as defined in the appended claims.

Examples

Embodiment Construction

[0016]The present invention will be described in greater detail with reference initially to a standard structure 50, illustrated in Figures 1a and 1b, to which a pair of folding doors hinged one to the other are attached.

[0017]Such a structure, which can generally, but not exclusively, be a structure of an item of furniture, substantially comprises a first fixed vertical part or upright 1, a second fixed vertical part or upright 4 and an upper lintel 5 provided horizontally between the two vertical uprights. The vertical uprights 1, 4 can be equivalent to pillars, walls, sides of an item of furniture, and so on. These elements define, together with an end surface, which can be represented by the base of an item of furniture or the floor itself, the perimeter of a compartment.

[0018]As mentioned previously, the structure is not limited exclusively to those of furniture, but can also be represented, for example, by a door, in particular a door for passage between two spaces, delimited ...

Claims

1. Mechanism for the opening and the closing of at least one pair of folding doors configured to be mounted on a structure (50; 100) comprising a first vertical upright (1), a second vertical upright (4) and an upper horizontal lintel (5) between the two vertical uprights (1, 4), wherein said at least one pair of folding doors consists of a first door (2; 102) hinged along one of its vertical edges to one of said vertical uprights (1, 4) to perform a rotation with vertical axis and a second door (3; 103) hinged along one of its vertical edges to the unrestrained vertical edge of the first door (2; 102) to perform a rotation with vertical axis, characterised in that it comprises: - a track (6; 106) intended to be installed on said lintel (5) and extending in a direction parallel to the direction of longitudinal development of the lintel (5); - a carriage (7; 107) intended to engage slidingly with said track (6; 106) between a start of travel position and an end of travel position; - a first connecting arm (10'; 110') fixed at one of its ends to said carriage (7; 107) in a rotating manner in a fulcrum point (22; 122) and intended to be fixed, at the other end, in a rotating manner to an upper crosspiece (11; 111) of the second door (3; 103) in a fulcrum point (24; 124); - a second connecting arm (10"; 110") fixed at one of its ends to said carriage (7; 107) in a rotating manner in a fulcrum point (23; 123) and intended to be fixed, at the other end, to an upper crosspiece (11; 111) of the second door (3; 103) in a fulcrum point (25; 125); wherein said first arm (10'; 110') and said second arm (10"; 110") have the same length, such that, in operation, the two arms (10' and 10"; 110' and 110") form with the fulcrum points (22 and 23; 122 and 123) on the carriage (7; 107) and with the fulcrum points (24 and 25; 124 and 125) on the upper crosspiece (11; 111) of the second door (3; 103) a parallelogram with angles that vary during the movement of opening and closing of the pair of doors, all the fulcrum points of the arms being mobile during the movement of opening and closing of the doors.

2. Mechanism according to claim 1, wherein at least one of said arms (10', 10"; 110', 100") provides in its lower part a pulley (13', 13"; 113', 113") intended to be received, during part of the movement of opening and / or closing, in a respective rotation guide (14', 14"; 114', 114") fixed to said lintel (5) of the structure (50; 100), to facilitate movement at the dead points.

3. Mechanism according to claim 1 or 2, wherein said track (6; 106) provides, at one of its ends arranged at the vertical upright (1, 4) whereto the first door (2; 102) is hinged, a retaining element or stop (15; 115) for limiting in closure the travel of the sliding carriage (7; 107).

4. Mechanism according to claim 3, wherein the sliding carriage (7; 107) is provided, at its end turned towards said retaining element or stop (15; 115), with a deceleration device capable of being actuated by the retaining element (15; 115) to slow down and dampen the movement of the doors in closure.

5. Mechanism according to any one of the preceding claims, wherein said sliding carriage (7; 107) is provided, at its end opposite that at the vertical upright whereto the first door (2; 102) is hinged, with a deceleration device capable of being activated upon contact with a closure support element defining the end of travel in opening of the carriage (7; 107) to slow down and dampen the movement of the doors in opening.

6. Mechanism according to claim 4 or 5, wherein said deceleration device is a protruding shock-absorbing piston designed to abut against a respective abutment surface of the retaining element (15; 115) and / or of said closure support element.

7. Structure (50), in particular defining a structure of an item of furniture, comprising a first vertical upright (1), a second vertical upright (4), an upper horizontal lintel (5) between the two vertical uprights (1, 4) and a pair of folding doors consisting of a first door (2) hinged along one of its vertical edges to said first vertical upright (1) to perform a rotation with vertical axis and a second door (3) hinged along one of its vertical edges to the unrestrained vertical edge of the first door (2) to perform a rotation with vertical axis, characterised in that it comprises a mechanism of opening and closing of folding doors according to one of the preceding claims.

8. Structure (100), in particular defining a structure of an item of furniture, comprising a first vertical upright (1), a second vertical upright (4), an upper horizontal lintel (5) between the two vertical uprights (1, 4) and two pairs of folding doors, said first pair of folding doors being composed of a first door (2) hinged along one of its vertical edges to said first vertical upright (1) to perform a rotation with vertical axis and a second door (3) hinged along one of its vertical edges to the unrestrained vertical edge of the first door (2) to perform a rotation with vertical axis, and said second pair of doors being composed in turn of a first door (102) hinged along one of its vertical edges to said second vertical upright (4) and a second door (103) hinged along one of its vertical edges to the unrestrained vertical edge of the first door (102) to perform a rotation with vertical axis, said structure (100) being characterised in that it comprises two mechanisms for opening and closing folding doors according to one of claims 1 to 7, arranged in a mirror fashion with respect to the centre plane of the structure (100), each one being associated with a respective pair of folding doors.

9. Structure (100) according to claim 8, comprising a synchronisation system configured to kinematically connect the linear movement of the sliding carriages (7, 107) of said mechanisms for opening and closing folding doors and to obtain a simultaneous synchronised and mirrored movement of the two pairs of doors in opening and closure.

10. Structure (100) according to claim 9, wherein said synchronisation system is a cable or belt system, a rack and pinion system, or a worm gear and nuts system.

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