"OSCILLATION MECHANISM FOR A CHAIR OR ARMCHAIR"

[0001]The present invention belongs to the field of the oscillation mechanisms for seats of chairs or armchairs, for example, office chairs or armchairs.

[0002]The field of chairs and armchairs, especially office chairs or armchairs, is highly demanding as regards comfort of use, so that modern solutions provide for multiple adjustments (for example, the height of the seat, the inclination of the backrest and seat, etc.), in order that the user may better adjust his/her position. [0003]Some solutions further include an oscillating backrest, so that it moves backwards when the user leans the back thereon, or an oscillating seat, so that it adapts to the position of the user, for example, sitting very forward or very backward.

[0004]The backrest and the seat oscillation possibilities are conferred by an oscillation mechanism supported at a predefined height by a stem and, in turn, carrying the seat and the backrest of the chair.

[0005]Some solutions of oscillation mechanisms are described in documents WO-A1-2010/097818, WO-A1- 2011/104735, WO-A1-2015/145216, IT201800003431, to the

Applicant. [0006]In such a field, competition is very strong and companies make considerable efforts to research and develop new solutions, both aimed at improving the comfort of the final product as well as at increasing the profitability of a product by lowering the production costs thereof.

[0007]In particular, given the structural and functional complexity of the oscillation mechanisms, considerable efforts are made to simplify such mechanisms.

[0008]It is the object of the present invention to provide an oscillation mechanism for a chair or armchair which meets the comfort requirements of the field and overcomes the drawbacks mentioned above regarding the structural complexity of the existing solutions.

[0009]Such an object is achieved by an oscillation mechanism according to claim 1. The dependent claims describe further advantageous embodiments.

[0010]The features and advantages of the oscillation mechanism according to the present invention will become apparent from the following description, given by way of non-limiting example, according to the accompanying drawings, in which:

[0011]- Figure 1 shows a chair provided with an oscillation mechanism according to an embodiment of the present invention; [0012]- Figure 2 illustrates the oscillation mechanism in Figure 1;

[0013]- Figure 3 depicts the oscillation mechanism in Figure 2, with separate parts;

[0014]- Figure 4 depicts a functional body of the oscillation mechanism, according to an embodiment of the invention;

[0015]- Figure 5 shows the oscillation mechanism in an initial or resting configuration; and

[0016]- Figure 6 depicts the oscillation mechanism in a final configuration.

[0017]With reference to the figures of the accompanying drawings, 1 indicates a chair or armchair as a whole, comprising a seat 2, a backrest 4, an oscillation mechanism 6, and a stem 8. [0018]The stem 8, consisting for example of a gas piston, supports the oscillation mechanism 6 at a predefined height with respect to a ground plane, and is adjustable according to the needs of the user.

[0019]The oscillation mechanism 6 comprises a seat coupling 10, which is mechanically connectable by means for example of screws, to the seat 2 of the chair.

[0020]Said seat coupling 10 extends between a rear portion 12, where it has a rear seat coupling axis 14, and a front portion 16, where it has a front seat coupling axis 18. [0021]The oscillation mechanism 6 further comprises a backrest coupling 20, which is mechanically connectable by means for example of screws, to the backrest 4 of the chair. [0022]For example, said backrest coupling 20, being for example L-shaped, comprises a rear coupling portion 22 intended for the connection to the backrest 6, and a front connection portion 24.

[0023]Said front connection portion has an upper backrest coupling axis 26 and a lower backrest coupling axis 28.

[0024]The seat coupling 10 is hinged to the backrest coupling 20 by engaging the rear seat coupling axis 14 with the upper backrest coupling axis 26, engaged by means of for example a first pin 30, which forms a rear hinge axis 30'.

[0025]The oscillation mechanism 6 further comprises a functional body 40 made in a single piece, for example by molding, of plastic material.

[0026]For example, said functional body 40 is made of polyamide.

[0027]The functional body 40 extends from a rear portion 42, where it has a rear body axis 44, to a front portion 46, where it has a front body axis 48, for example obtained by means of a plurality of hinge elements 50 52, separated along said front body axis 48. [0028]The functional body 40 is hinged to the backrest coupling 20 by engaging the lower coupling axis 28 with the rear body axis 44 by means for example of a second pin 54, which forms a lower hinge axis 54'. [0029]The functional body 40 is hinged to the seat coupling 10 by engaging the front body axis 48 with the front seat coupling axis 18 by means for example of a third pin 56, which forms a front hinge axis 56'.

[0030]The functional body 40 is configured to be elastically deformable, by bending, between the rear body axis 44 and the front body axis 48, i.e., between the lower hinge axis 54' and the front hinge axis 56'.

[0031]According to a preferred embodiment, the functional body 40 has, between the rear body axis 44 and the front body axis 48, differentiated-flexibility zones, and in particular a low flexibility zone 60, which is proximal to the rear body axis 44, and a high flexibility zone 62, which is proximal to the front body axis 48.

[0032]For example, the functional body 40 comprises, within said low flexibility zone 60, a plurality of ribs 64, which structurally accentuate the bending rigidity of said low flexibility zone 60.

[0033]By virtue of the deformability of the functional body 40, the oscillation mechanism 6 is suitable for switching from an initial or resting configuration (Figure 4), in which the front hinge axis 56' and the rear hinge axis 30' lie on a first imaginary plane 70, to a final configuration (Figure 6), in which the front hinge axis 56' and the rear hinge axis 30' lie on a second imaginary plane 72.

[0034]The second imaginary plane 72 is inclined with respect to the first imaginary plane 70 by an angle corresponding to the maximum inclination of the seat.

[0035]According to an embodiment, the mutual distance between the front hinge axis 56', the rear hinge axis 30', and the lower hinge axis 54' is configured so that the position taken by the rear hinge axis 30' in the final configuration is placed at a predefined height H above the first imaginary plane 70. [0036]In other words, such a feature ensures that the oscillation mechanism is of the "self-weighting" type. [0037]According to an embodiment of the invention, the oscillation mechanism 10 further comprises adjustment means adapted to adjust manually the flexibility of the functional body 40.

[0038]For example, said adjustment means comprise a bracket 80 which cooperates with the functional body 40, so as to structurally stiffen it, and is manually positionable between the rear portion 42 and the front portion 46. For example, the bracket 80 cooperates with the functional body 40 by sliding on an upper surface 82 of said functional body.

[0039]When the bracket 80 is proximal to the rear portion 42, the region of the functional body 40 which spans from the bracket 80 to the front body axis 48 is free from stiffenings and therefore has a high flexibility; as the bracket 80 is positioned closer to the front body axis 48, the high flexibility zone is reduced.

[0040]Preferably, said adjustment means comprise a knob 84 sliding along a lower surface 87 of the functional body 40, connected to the bracket 80 by means of slots 86, 88 obtained through the thickness of the functional body 40. [0041]According to a variant of the invention, the functional body comprises a unitary flexible portion, i.e., consisting of a single piece, made of a deformable material, typically a plastic material, which, by virtue of the elastic deformability of the material, allows the oscillation of the seat and backrest.

[0042]According to a further variant of the invention, the differentiated-flexibility zones have a different rigidity as they are made of different materials, having different elastic features.

[0043]Innovatively, the oscillation mechanism according to the present invention meets the needs of the field, since it allows the seat and backrest of a chair or armchair to be inclined, while overcoming some of the aforementioned drawbacks, since it is particularly simplified structurally.

[0044]In fact, the deformable functional body integrates in a single piece, which is easily achievable by molding plastic materials, the typical functions of the steel or aluminum box and the steel springs of the prior art solutions.

[0045]Moreover, advantageously, the user may easily adjust the rigidity of the oscillation mechanism, according to his/her own comfort needs.

[0046]It is apparent that, in order to meet contingent needs, those skilled in the art may make changes to the oscillation mechanism described above, all contained within the scope of protection as defined by the following claims.