Friction hinge for bending elements of upholstered furniture

Abstract

In seating furniture, upholstered elements such as backrests, armrests or backs are provided, which comprise joint mechanisms therein adapted to allow the upholstered element to assume variable configurations. In such mechanisms, the joint is made by means of friction hinges comprising a first coupling element integral with a fixed portion and adapted to define the axis of rotation, a second coupling element integral with a movable portion of the mechanism and having a conical surface coaxial with said first element, a third, self-lubricating element, interposed between said first and second element, and further comprise biasing assemblies on which an adjusting nut acts to adjust the force necessary to obtain the joint movement of the movable portion with respect to the fixed portion.

Description

TECHNICAL FIELD

[0001] The present invention falls within the technical field related to articles of furniture, with particular reference to armchairs and sofas and concerns a friction hinge used in mechanisms housed inside upholstered elements to carry out a reciprocal movement of portions of the upholstered element.BACKGROUND ART

[0002] As is known, armchairs and sofas have, with respect to all other seating items, a very high level of comfort resulting from generous dimensions, soft upholstery and ergonomic shapes aimed at allowing a comfortable and relaxing posture.

[0003] These posture characteristics assume significant importance, as highlighted in European patent EP2981194 on behalf of the same applicant, especially if seated in the armchair or on the sofa for several hours. In fact, the human body requires changing the position assumed after a certain period of time, regardless of the reason for sitting, such as reading, watching television programs, talking or simply resting.

[0004] In the same industrial property above, an upholstered element with a variable shape is disclosed which allows the shape of backrests, sides or armrests in sofas or armchairs to be easily varied, and thus the body position to be modified without having to resort to the use of additional cushions or the purchase of armchairs and sofas provided with what is called "relaxation movement", i.e., means adapted to vary the seating position, or provided with mechanisms which, on request, cause the exit of footrests suitable for supporting the legs in a horizontal position.

[0005] The aforesaid element with variable shape essentially consists of an upholstered cushion inside which there is a fixed frame constrained to the supporting structure of the sofa or armchair and at least two movable frames rotationally constrained to the fixed frame by means of a friction hinge, so that the upholstered cushion can assume different stable shapes to offer the user innovative support methods for the different parts of the body and as many personalised postures.

[0006] A detailed description of the aforesaid friction hinge is not present in the patent in question, as this is outside the scope thereof and yet such a component is of fundamental importance for the creation of reliable products of convenient use.

[0007] In fact, it is necessary to consider that the friction hinge is intended to be housed inside upholstered elements, whereby once assembled, it is embedded inside upholstery which in turn is contained inside a sewn covering whereby the hinge is no longer accessible. This means that the hinge must be able to operate for a long time and for as many work cycles as possible without it being possible to perform maintenance and adjustment operations thereon.

[0008] Furthermore, in view of the variety of sizes and loads acting on the mechanisms which incorporate the hinge, depending on their specific purpose such as sides, armrests, backrests, seats, a specific design is currently in place, and a consequent specific creation, for each specific upholstered element.

[0009] It is therefore desirable to find a solution based on a mechanical diagram such as to be extremely stable and reliable and at the same time validly applicable for many different types of upholstered elements and ensure, at the same time, the required characteristics of easy adjustment of the position and maintenance of the same position in the desired configuration of use.SUMMARY OF THE INVENTION

[0010] The main object of the present invention is to propose a friction hinge intended for use in upholstered elements with variable shape, which has a high stability and reliability over time in allowing an easy adjustment of the configuration of the upholstered element, in particular whether it is a side of a sofa or an armchair or the head of a bed.

[0011] Another object of the invention is to provide a friction hinge mechanism adapted to ensure the mutual rotation of frames present inside upholstered elements following pressure and / or movement and also adapted to maintain the mutual position of said frames while forces of various magnitude related to the use of the aforesaid elements act thereon.

[0012] A further object of the invention consists in proposing a hinge mechanism for upholstered elements which allows the rotation, in frictional mode, of frames present inside said upholstered elements, with a high level of reliability.

[0013] The above objects are fully achieved by a friction hinge, in particular for reclining elements of upholstered furniture, in which the following are provided: a first coupling element adapted to define an axis of rotation; a second coupling element having a conical surface coaxial with said first coupling element; a friction-reducing element in self-lubricating material, interposed between said first coupling element and said second coupling element, and having a second conical surface; a biasing assembly which pushes said first coupling element towards said second coupling element, which comprises a threaded portion which inserts into an opening of said first coupling element and which is engaged by an adjusting nut, said biasing assembly consisting of disc springs arranged facing each other in pairs on which said adjusting nut acts.

[0014] A friction hinge as outlined above has a high stability over time even following numerous operating cycles and allows an operator to manually adjust in a very simple and precise manner the torque which must be applied on the hinge to reciprocally rotate the coupling elements.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The characteristics of the invention will become apparent from the following disclosure of preferred embodiments of the hinge in question, in accordance with what is reported in the claims and with the aid of the attached drawings, in which: Fig. 1 illustrates a sectional view of the friction hinge of the invention applied to a movement mechanism applicable inside an upholstered article of furniture; Fig. 2 illustrates an exploded view of the hinge of Fig. 1; Fig. 3 illustrates a transparent side view of an upholstered article of furniture comprising frames articulated to each other by a hinge according to the invention; Fig. 3A illustrates a side view of the furniture of Fig. 3, in which one of the articulated frames is positioned in a reclined configuration. DISCLOSURE OF PREFERRED EMBODIMENTS

[0016] In the above-listed figures, a friction hinge according to the present invention has been indicated with reference numeral 10.

[0017] The hinge 10 is intended for use in movement mechanisms, 70, of the type adapted to be inserted inside upholstered furniture to form a hinging joint of a fixed part with respect to a movable part of an upholstered element.

[0018] Referring to Figures 1 and 2, the hinge 10 comprises a first coupling element 1 having a substantially cylindrical shape with one side open and with the opposite side, 12, closed, in which there is, centrally, a circular opening 13. This first coupling element 1 defines an axis of rotation X. The first coupling element 3 is integral with a fixed portion, 60, of the movement mechanism 70.

[0019] The hinge 10 further comprises a second coupling element 2 having a main body 22 coaxial to said first coupling element 1. The main body 22 has a conical outer surface 21. Advantageously, the taper of the main body 22 is less than 1 / 3. At a smaller base end 24 of the conical portion, said second coupling element 2 has a threaded appendage 23, the function of which is illustrated below. At the larger base end 25 of the conical portion, the second coupling element 2 is connected to an arm 50 which has at least one radial portion 51 extending away from the axis X of the friction hinge 10 and a distal portion 52 which is at an average distance, b, from the axis X of the friction hinge.

[0020] Furthermore, the hinge 10 comprises a self-lubricating element 3 interposed between said first coupling element 1 and said, said self-lubricating element 3 having a cylindrical outer surface 31 and a conical inner surface 32 corresponding to and matching respectively with the cylindrical inner surface 11 of the first coupling element 1 and with the conical surface 21 of the second coupling element 2. Advantageously, the self-lubricating material has a coefficient of static friction not exceeding 0.1 and a coefficient of dynamic friction not exceeding 2 / 3 of the coefficient of static friction.

[0021] The hinge 10 lastly comprises a biasing assembly 4 which pushes said first coupling element 1 towards the second coupling element 2 to keep the elements of the friction hinge in a stable coupling configuration with a certain contact pressure of the respective coupling surfaces. The biasing assembly 4 consists of a plurality of disc springs 42 facing in pairs and interposed between the circular base surface 12 of the first coupling element 1 and a nut 41 screwed onto said threaded appendage 23 of said second coupling element 2. Advantageously, the biasing assembly 4 comprises at least three pairs of disc springs 42 facing each other. By acting on the nut 41, it is possible to easily and precisely vary the elastic reaction exerted by said disc springs 42 and, consequently, the pressure of the self-lubricating element 3 on the conical surface of said second coupling element 2; in fact, it should be noted that said first coupling element 1 acts axially, with its own base surface 12, on said self-lubricating element 3.

[0022] Therefore, thanks to the mechanical diagram of the hinge 10 as illustrated above, a given adjustment of the compression of the biasing assembly 4 corresponds to a certain degree of friction exerted by the hinge 10 on the contact surfaces 21, 32, and this makes it possible to adopt, during the construction of the upholstered furniture, a degree of adjustment which is optimal, for the dimensions and loads associated with the furniture itself, for the purposes of the desired reciprocal positioning of the frames related to the two portions of the furniture connected to each other by means of the aforesaid hinge.

[0023] More specifically, the low conicity value of the main body 22 and of the corresponding inner surface 32 of the self-lubricating element 3 allows to both limit the overall diameter of the hinge 10 and to have a high adjustment precision of the stabilizing frictional force, since high variations of the preload of the biasing assembly 4 correspond to small variations of the frictional force. Thereby, it is also possible to choose disc springs with a high elasticity coefficient without affecting the possibility of a precise adjustment. Furthermore, the possibility of precisely adjusting the frictional force allows on the one hand to be able to perform the operation manually without requiring a particular skill, and to easily adapt the adjustment manually to different applications with average distance b of the distal portion 52 of the arm 50 from the hinge axis X which are also very different from each other and with expected loads applied to the aforesaid distal portion 52 which are also very different from each other.

[0024] Furthermore, it has been experimentally verified that the use of a number of pairs of disc springs equal to 3 or more allows to obtain a range of adjustment which comprises all possible applications of interest.

[0025] Finally, the choice of a self-lubricating material 3 having a coefficient of dynamic friction which is suitably lower with respect to the relative coefficient of static friction is particularly important in the specific applications for which the friction hinge 10 of the invention is intended. In fact, this allows for a high stability of the configuration assumed by the upholstered element and at the same time to be able to perform an easy movement of the movable portion when sufficient force is applied thereon to overcome the static friction of the friction hinge 10.

[0026] Figures 3 and 3A show, in transparent side view, an example of upholstered furniture comprising at least one hinge 10 according to the invention. In this case, it is a sofa, or armchair, in which the cushion 100 which constitutes the backrest of the piece of furniture has a reclining portion. In the lower zone 101 of the cushion 100, there is a fixed frame 60 which supports the backrest itself; said frame 60 is constrained to extend upwards perpendicularly to the base structure 70 which supports the seat cushion 110 of the sofa, or armchair. The structure 70 is also provided with support feet 71 of the known art.

[0027] The movable arm 50 is constrained at the upper end of the fixed frame 60 by the hinge 10, the movable arm being intended to support the reclining portion of the backrest, which can be rotated around the axis X to the horizontal position illustrated in Fig. 3A, which rotation can certainly be stopped in any intermediate position in relation to the user's desire to configure, at a given moment, the sofa or armchair, in a manner useful for assuming a certain posture.

[0028] From the foregoing, the advantages related to the use of the friction hinge of the invention within upholstered furniture elements in which it is desired to obtain a variable configuration of a movable portion with respect to a fixed portion are evident.

[0029] It is clear that variants can be implemented with respect to the above described embodiments, for example variations in the specific geometry of the individual components which define the friction hinge 10.

[0030] It has also been verified that the optimum degree of adjustment for most applications is obtainable by employing a number of pairs of disc springs 42 equal to three. Certainly a greater number of disc springs can be used according to the size of the disc springs used and the type of element of the furniture to be reclined with respect to the fixed structure of the furniture itself.

[0031] These and other variants can be made and it is however understood that the foregoing is of exemplary and non-limiting value, therefore any further variations in detail which may become necessary for technical and / or functional reasons, are considered from now on to fall within the same protective scope defined by the following claims.

Claims

1. Friction hinge (10) for mechanisms housed within upholstered elements (100) of furniture to achieve a reciprocal movement of portions of the upholstered element (100), said friction hinge (10) comprising: - a first coupling element (1) defining an axis of rotation (X); - a second coupling element (2) having a conical surface (21) and being coaxial to said first coupling element (1); - a self-lubricating element (3) interposed between said first coupling element (1) and said second coupling element (2) and having a second conical surface (32); - a biasing assembly (4) which pushes said first coupling element (1) towards said second coupling element (2); said friction hinge (10) being characterised in that - said second coupling element (2) comprises a threaded portion (23) which is inserted in an opening (13) of said first coupling element (1) and which is engaged by an adjusting nut (41); - said biasing assembly (4) consisting of a plurality of pairs of disc springs (42) arranged facing each other on which said adjusting nut (41) acts.

2. Friction hinge according to the preceding claim, characterised in that said pairs of disc springs (42) are three in number.

3. Friction hinge according to claim 1, characterised in that the taper of said conical surfaces (21, 32) is less than 1 / 3.

4. Friction hinge according to claim 1, characterised in that the self-lubricating material has a coefficient of static friction not exceeding 0.1 and a coefficient of dynamic friction not exceeding 2 / 3 of the coefficient of static friction.

5. Friction hinge according to claim 1, characterised in that at the larger base end (25) of the conical portion (22) the second coupling element (2) is connected to an arm (50) which has at least one radial portion (51) extending away from the axis (X) of the friction hinge (10) and a distal portion (52) which is at an average distance (b) from the axis (X) of the friction hinge (10).

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