DESCRIPTION

The invention relates to a lifting system for furniture piece doors oscillating around a horizontal axis, in particular for lifting doors of hood units.

In the furniture industry the use of lifting systems for supporting and vertically moving doors of kitchen hood units is well known; each of these systems comprises one or more support levers connected in an articulated manner between the body of the furniture piece and the door to be lifted, as well as comprising an elastic device, for example a gas spring, operatively connected to the lever so as to exert the necessary force for lifting the door.

Conventionally, the operative connection between the lever and the elastic device can be indirectly achieved through an oscillating intermediate member, to which the elastic device is connected, which member has a roller that acts upon a cam of the support lever so as to transmit the force of the elastic device to the lever itself.

Alternatively, the operative connection between the lever and the elastic device can be directly achieved by providing an articulation pin on the support lever to connect the rod of the piston of the elastic device itself, the pin being disposed at a distance from the oscillation axis of the support lever, a solution that is preferable because of its greater constructive simplicity.

Within the realm of such lifting systems, there exists a need to be able to control the lifting movement while it is taking place, in particular in the area where the moment generated by the weight of the door reaches its peak, as well as a need to be able to keep the door stationary in any position during opening, once the desired position has been reached. In fact, since the gas spring delivers a force that varies in a limited manner during its extension, in such lifting systems, especially if the gas spring is directly connected to the lever, it may occur that the torque exerted by the spring during a first opening arc of the hood unit is preponderant relative to the torque opposed by the weight force of the door or doors, whereas in another opening arc, corresponding to the maximum extension of the hood unit toward the exterior of the furniture piece, in which the torque takes on the highest value due to the weight of the door, the torque of the spring is lower than it, so that the hood unit can neither be maintained in the desired position, nor pushed toward the maximum opening position.

Furthermore, for the purpose of an effective lifting of the door, there exists a need to achieve a lifting force adaptable to the characteristics of the door, such as, for example, the weight, material or the thickness of the door.

Finally, through the use of such systems it has been possible to observe a technical problem consisting in the fact that the gas spring tends to lose efficiency over time, to the point where it may prove incapable of delivering the force necessary to lift the door or keep the door in a raised position, with the risk that the door itself may fall.

The main object of the invention is thus to provide a lifting system capable of fulfilling the user's needs and of solving the above-mentioned problems.

Within the scope of this technical task, one object of the invention is to realize a lifting system for furniture piece doors oscillating around a horizontal axis which provides precise control over the lifting of the door and enables the effectiveness of such control to be maintained unaltered over time.

The technical task, as well as these and other objects, according to the present invention are achieved by realizing a lifting system for a furniture piece door oscillating around a horizontal axis having a support lever of the door oscillating around an oscillation pin disposed on an inner side of a shoulder of the furniture piece and a first elastic device operatively connected to the support lever of the door to provide a moment in the closing direction of the door at the closed position of the door, and a primary moment in the opening direction of the door starting from a partial opening position of the door, characterized in that it comprises a second elastic device operatively connected to the shoulder and to the support lever so as to provide a force suitable for generating, relative to said oscillation pin, an auxiliary moment in the opening direction of the door and/or respectively an opposing moment via friction against the support lever in the direction opposite to the closing movement of the door along an arc of oscillation around the maximum extension of the door toward the furniture piece exterior.

Whereas the auxiliary opening moment is summed to the opening moment generated by the first elastic device, the friction moment is suitable for opposing the movement of the hood unit, compensating for any differences between the moments generated by the first elastic device and the weight force so as to keep the hood unit in equilibrium.

The second elastic device is configured in a manner such as to provide, at said arc of oscillation of the door, an auxiliary moment in the opening direction of the door, which, summed with the primary moment in the opening direction of the door, substantially equals or prevails over the moment in the closing direction of the door due to the weight force of the door and the other parts integral therewith.

Preferably, the second elastic device has means for adjusting its own force generating said auxiliary moment and/or said opposing moment.

Via such adjustment means it is possible to act upon the device in such a way as to modify its operation, according to whether one desires a movement of the door that remains in equilibrium in the various partial opening positions or one prefers a continuous opening of the door with a movement of greater or lesser speed.

Moreover, said adjustment means are particularly advantageous for adapting the operation of the device to different weights of doors of different materials or thickness.

Preferably, the second elastic device has a friction surface slidable along a cam provided on said support lever.

Preferably, the second elastic device comprises a leaf spring having said friction surface.

Preferably, said leaf spring has an angular configuration defining a first spring arm on which said friction surface is present and a second spring arm.

Preferably, said adjustment means comprise an element for adjusting the pre- compression of said leaf spring.

Preferably, said adjustment element comprises an eccentric operatively engaged with said second arm of said leaf spring.

In a further embodiment the second elastic device comprises, as an alternative to or in combination with said adjustment element, elements which are abutted against zones of said cam with differentiated friction, made in particular of a different material.

Further characteristics and advantages of the invention will be more apparent from the description of a preferred, but not exclusive embodiment of the lifting system for furniture piece doors oscillating around a horizontal axis according to the invention, illustrated by way of non-restrictive example in the appended drawings, in which: figure 1 shows a side elevation view of a hood unit with a double door having a lifting system for the double door in accordance with the invention, in the closed position of the double door;

figure 2 shows a side elevation view of the hood unit of figure 1 in a partially open position of the double door;

figure 3 shows a side elevation view of the hood unit of figure 1 in the completely open position of the double door;

figure 4 shows an enlarged detail of the hood unit of figure 1 in the closed position of the double door, with the eccentric in a first position of adjustment of the compression of the leaf spring;

figure 5 shows an enlarged detail of the hood unit of figure 3 in the open position of the double door, with the eccentric in the first position of adjustment of the compression of the leaf spring;

figure 6 shows an enlarged detail of the hood unit of figure 3 in the open position of the double door, with the eccentric in a second adjustment position which corresponds to a greater compression of the leaf spring compared to the first adjustment position;

figure 7 shows a side elevation view of a hood unit with a single door having a door lifting system in accordance with the invention, in the closed position of the door;

figure 8 shows a side elevation view of the hood unit of figure 7 in the open position of the door;

figure 9 graphically shows the trend of the moments to which the double door is subjected depending on the opening angle of the upper door and also with the varying of the adjustment by means of the eccentric; figure 10 graphically shows the trend of the moments to which the double door is subjected depending on the opening angle of the upper door and also with the varying of the performance of the gas spring.

Equivalent parts of the lifting system of the two versions of hood units illustrated will be indicated with the same numerical reference.

With reference to the cited figures, there is shown a lifting system for doors of furniture pieces, such as hood units, which envisage an axis of oscillation around a horizontal axis.

With reference to the embodiment illustrated in figures 1 - 6, the hood unit 2 has a an upper door 3 constrained by means of one or more hinges 4 of a known type to the inner side of the top 5 of the hood unit 2, and by means of one or more hinges 6 of a known type to a lower door 7, in turn constrained to at least a support lever 9 by means of a decelerated hinge 8 of a known type positioned on the inside of the door 7.

The support lever 9, at the end opposite to the one articulated with the hinge 8, is constrained by means of an oscillation pin 10 to a plate 11 applied to the inner side of a shoulder 12 of the hood unit 2.

The axes of oscillation defined by the oscillation pin 10 and by the hinges 4, 6, 8 are all orientated parallelly and horizontally in the direction of width of the hood unit 2.

With reference to the embodiment illustrated in figures 7 and 8, the hood unit 23 has a single door 13 constrained by means of one or more decelerated hinges 14 of a known type to the inner side of the top 15 of the hood unit 23 and, by means of at least one kinematic chain comprising a connecting rod 17 and a support lever 19, to a plate 21 applied to the inner side of a shoulder 22 of the hood unit 23. In particular, the door 13 is constrained, by means of at least one hinge 16 of a known type, to one end of the connecting rod 17, whose opposite end is in turn constrained, by means of an oscillation pin 18, to the support lever 19, which is in turn constrained to the plate 21 by means of an oscillation pin 20.

The axes of oscillation provided by the oscillation pins 18 and 20 and by the hinges 14 and 16 are all oriented parallelly and horizontally in the direction of width of the hood unit 23.

The hood unit 2 and respectively the hood unit 23 have respective systems for moving the doors 3 and 7 and respectively the door 13, comprising a first elastic device operatively connected to the support lever 9 and respectively to the support lever 19 to provide a moment in the closing direction of the doors 3 and 7 and respectively of the door 13 at the closed position of the doors 3 and 7 and respectively of the door 13, and a primary moment in the opening direction of the doors 3 and 7 and respectively of the door 13, starting from a partial opening position of the doors 3 and 7 and respectively of the door 13.

The elastic device of the hood unit 2 and respectively of the hood unit 23 comprises a gas spring 24 having a cylinder 25 fulcrumed with the oscillation pin 26 to the plate 11 and respectively to the plate 21 , and a piston rod 27 fulcrumed with the oscillation pin 28 to the support lever 9 and respectively to the support lever 19.

The oscillation pins 26 and 28 of the elastic device of the hood unit 2 and respectively of the hood unit 23 are parallel to the pin 10 and respectively to the pin 20.

The system for moving the doors 3 and 7 and respectively the door 13 further comprises a second elastic device operatively connected to the support lever 9 and respectively to the support lever 19 to provide an auxiliary moment of elastic force and/or a friction force acting against the support lever 9 and respectively against the support lever 19 in the opening direction of the doors 3 and 7 and respectively of the door 13, starting from a partial opening position thereof, along an arc of oscillation thereof.

Advantageously the arc of oscillation of the doors 3 and 7 and respectively of the door 13 in which said second elastic device operates is around the position of maximum extension of the door towards the furniture piece exterior, where the closing moment exerted by the weight force of the doors 3 and 7 and respectively of the door 13 and the other parts integral therewith takes on the maximum value. The second elastic device can be configured in a manner such as to to deliver, at said arc of oscillation of the doors 3 and 7 and respectively of the door 13, an auxiliary moment in the opening direction, which, summed with the primary moment in the opening direction and taking duly into account the friction in play, prevails over the moment in the closing direction of the doors 3 and 7 and respectively of the door 13 due to the weight force of the doors and the other parts integral therewith.

In such a case the second elastic device assures a continuous opening movement of the doors 3 and 7 and respectively of the door 13.

But the second elastic device can alternatively also be configured in a manner such as to deliver, at said arc of oscillation of the doors 3 and 7 and respectively of the door 13, an auxiliary moment in the opening direction, which, summed with the primary moment in the opening direction and taking duly into account the friction in play, substantially balances the moment in the closing direction of the doors 3 and 7 and respectively of the door 13 due to the weight force of the doors and the other parts integral therewith.

In such a case, the second elastic device assures a plurality of stable partial opening positions of the doors 3 and 7 and respectively of the door 13, in which, if the user releases his/her hold, the doors will remain stationary in the position reached.

The second elastic device in particular is provided with special adjustment means by means of which, as we shall see, the value of the auxiliary moment delivered can be modulated.

In the illustrated embodiments, the second elastic device comprises a leaf spring 29 having a friction surface 30 slidable along a cam 31 provided on the support lever 9 and respectively on the support lever 19.

The cam 31 is defined by a specific surface profile at the end of the support lever 9 and respectively of the support lever 19, which may be coated with a different material, and which has the oscillation pin 10 and respectively the oscillation pin 20.

The cam 31 has a neutral section defining an arc of circumference centred on the oscillation pin 10 and respectively on the oscillation pin 20, along which the elastic force transmitted by the leaf spring 29 is directed radially relative to the oscillation pin 10 and respectively to the oscillation pin 20 of the support lever 9 and respectively of the support lever 19, and an active section having a differente radius of curvature, along which the elastic force transmitted by the leaf spring 29 exhibits a moment arm relative to the oscillation pin 10 and respectively to the oscillation pin 20 of the support lever 9 and respectively of the support lever 19.

The leaf spring 29 has an angular configuration defining a first spring arm 32 on which the friction surface 30 is present and a second spring arm 33.

The leaf spring 29 has a middle curved section 34 from which there extends the first spring arm 32 and on the opposite side the second spring arm 33, both extending rectilinearly.

The middle curved section 34 is clamped between a block 35 which is fixed to the plate 11 and respectively to the plate 21, disposed on the concave side of the middle curved section 34, and an orthogonal tab 36 of the plate 11 and respectively of the plate 21 , disposed on the convex side of the middle curved section 34.

The means for adjusting the auxiliary moment delivered by the second elastic device can take different forms.

The adjustment means can in fact comprise an element for adjusting the pre- compression to which the leaf spring 29 is subjected in the closed position of the doors 3 and 7 and respectively of the door 13.

The adjustment element comprises in particular an eccentric 37 operatively engaged with the second arm of the spring 33.

The eccentric 37 is fulcrumed to the plate 11 and respectively to the plate 21 by means of the oscillation pin 38 parallel to the oscillation pin 10 and respectively to the oscillation pin 20 and is suitable for carrying out an eccentric oscillation of around 180°, limited by a specific stop 39, between a first adjustment position (fig. 4), which corresponds to a lower pre-compression of the second spring arm 33 and a second adjustment position (fig. 6), which corresponds to a higher pre- compression of the second spring arm 33.

The adjustment means can comprise, as an alternative to or in combination with the eccentric 37, zones of the cam 31 with differentiated friction, and in particular zones of the cam 31 made of different material.

Let us now make reference to figure 9, which graphically shows the trend in the moments to which the double door 3, 7 of the hood unit of figure 1- 6 is subjected depending on the opening angle of the upper door 3, where al indicates the opening angle in which the second elastic device operates.

The trend in the moment generated by the first elastic device is represented, for opening angles smaller than al , by the thin solid line, whereas for opening angles larger than al it is represented by the dashed line.

The trend in the moment in the closing direction of the doors 3, 7 due to the weight of the doors 3, 7 and of the parts lifted therewith (for example the hinges 6 and 8) is represented by the thick solid line.

The trend in the moment in the opening direction of the doors 3, 7 generated by the combination of the first elastic device with the eccentric 38 in the first adjustment position and the second elastic device for opening angles larger than al is represented by the thin solid line.

The trend in the moment in the opening direction of the doors 3, 7 generated by the combination of the first elastic device with the eccentric 37 in the second adjustment position and the second elastic device for opening angles larger than al is represented by the dash-dot line.

The graph shows that at the closing angle (point of origin of the graph), the moment generated by the first elastic device is negative, i.e. it operates in the closing direction of the doors 3, 7.

Once a certain angle al is reached, the moment generated by the first elastic device becomes zero (the line of action of the piston 27 of the gas spring against the support lever 9 is radially directed at the oscillation pin 10 of the support lever 9), and upon exceeding the angle al it becomes positive, i.e. it operates in the opening direction of the doors 3, 7 (the line of action of the piston 27 of the gas spring against the support lever 9 passes from one side to the diametrically opposite side of the oscillation pin 10 of the support lever 9).

Up to the opening angle a3 the moment in the closing direction due to the weight force prevails over the moment in the opening direction exerted by the first elastic device, and the opening of the doors 3, 7 must therefore be aided by the user.

Once the opening angle 3 is exceeded, the moment in the closing direction due to weight force is exceeded by the moment in the opening direction exerted by the first elastic device and the opening continues with no need for the user's intervention.

Once the opening angle l is also exceeded, a second concurrent moment exerted by the second elastic device is added to the moment in the opening direction exerted by the first elastic device.

The second elastic device advantageously operates around the position of maximum extension of the door towards the furniture piece exterior, i.e. when the moment in the closing direction generated by the weight force takes on the maximum value.

If the second elastic device were not present, the moment in the opening direction of the doors 3, 7 due solely to the first elastic device would be insufficient to overcome the moment in the closing direction due to the weight force. This is graphically illustrated by the fact that for opening angles larger than a4 the curve representing the former lies below the curve representing the latter.

For opening angles larger than al, the graph illustrates a section of overlapping between the curve of the moment in opening direction generated by the combination of the first elastic device and second elastic device with the eccentric 37 in the first adjustment position, and the curve of the moment in the closing direction generated by the weight force. In this overlapping section the doors 3, 7 exhibit a stable partially open position in the absence of the user's intervention.

If the user adjusts the eccentric 37 to the second adjustment position, which corresponds to a greater pre-compression of the leaf spring 29 and consequently to a greater elastic force transmitted by the latter to the cam 31 , the moment in the opening direction generated by the combination of the first elastic device and second elastic device becomes preponderant relative to the moment in the closing direction generated by the weight force, and the doors 3, 7 open completely in an automatic manner without the need for any intervention on the user's part.

Let us now make reference to figure 10, which graphically shows the trend in the moments to which the double door 3, 7 of the hood unit of figure 1- 6 is subjected depending on the opening angle of the upper door 3, and with the varying of the performance of the first elastic device, it being well known, in particular, that gas springs can undergo a progressive decline in performance over time, particularly as a result of small gas leaks.

The trend in the moment generated by the first elastic device at full efficiency is represented by the solid line, whereas the trend in the moment generated by the first elastic device after a loss of efficiency is represented by the dashed line.

The trend in the moment in the closing direction of the doors 3, 7 due to the weight force of the door 3, 7 and the other parts integral therewith is represented by the thick solid line.

The trend in the moment in the opening direction of the doors 3, 7 generated by the combination of the first elastic device and second elastic device for opening angles larger than al, which is the angle at which the second elastic device is first triggered, is represented by the dash-dot line. The graph shows that without the aid of the second elastic device, in the event of a loss of efficiency, the first elastic device could not achieve complete automatic opening of the doors 3, 7, given that, once the opening angle a4 was exceeded, the moment in the closing direction due to the weight force would prevail over the moment in the opening direction exerted by the first elastic device.

It should be noted that the second elastic device can be calibrated, according to preference, in a manner such as to cause a continuous movement of the doors 3, 7 toward the position of complete opening without the user's intervention (the curve of the moment in the opening direction generated by the combination of the first and second elastic device remains permanently above the curve of the moment in the closing direction generated by the weight force, as shown in the graph of figure 10) or a movement through stable partial opening positions (the curve of the moment in the opening direction generated by the combination of the first and second elastic device overlaps, in one section, the curve of the moment in the closing direction generated by the weight force, as shown in the graph of figure 9). It has been practically ascertained that the lifting system for a furniture piece door according to the invention is suitable for ensuring complete control over the opening of the door.

The lifting system for a furniture piece door thus conceived is susceptible of numerous modifications and variants, all falling within the scope of the inventive concept; moreover, all the details may be replaced with other technically equivalent elements.

In practice, the materials used, as well as the dimensions, can be any whatsoever according to need and the state of the art.