Patent Publication Number: US-2016235206-A1

Title: Chair with a tilting seat

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of Italian patent application number 102015000006504, filed Feb. 17, 2015, which is herein incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a chair comprising a seat and a backrest, in which the backrest is tiltable backwards relative to the seat under a backward thrust applied by the user. 
     2. Description of Prior Art 
     In the state of the art, many chairs are known with backrests that are tiltable under a backward thrust applied by the user. The document EP-A-14196090.6 by the same Applicant describes a chair comprising a fixed support structure including a pair of front legs and a pair of rear legs, a seat, fixed to the fixed support structure, and a backrest with a backrest panel with an arcuate shape connected in an oscillating manner to the fixed support structure. The backrest comprises two side connecting elements of plastic material, each of which comprises a cylindrical sleeve fixed to an upper portion of a respective rear leg. The side connecting elements of the backrest have respective bellows-shaped deformable portions, integrally formed with the respective cylindrical sleeve. The bellows-shaped deformable portions are connected in a fixed manner to respective side portions of the backrest panel. 
     Monocoque chairs are characterized by a monolithic structure in which the seat and backrest are formed as a single molded panel of plastic material. Monocoque chairs do not usually have backwardly-tiltable backrests. 
     SUMMARY OF THE INVENTION 
     The present invention aims to provide a monocoque chair equipped with a tiltable backrest. 
     According to the present invention, this object is achieved by a chair having the characteristics forming the subject of claim  1 . 
     The claims form an integral part of the disclosure provided here in relation to the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein: 
         FIG. 1  is a perspective view of a monocoque chair according to the present invention. 
         FIG. 2  is a rear perspective view of the chair of  FIG. 1 . 
         FIG. 3  is a perspective view on an enlarged scale of the part indicated by the arrow III in  FIG. 1 . 
         FIG. 4  is a cross-section along the line IV-IV of  FIG. 1 . 
         FIGS. 5 and 6  are longitudinal cross-sections of the chair of  FIG. 1 , in the rest position and in the backward-tilted position, respectively. 
         FIG. 7  is a perspective view illustrating a variant of the chair of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to the figures, numeral  10  designates a chair according to the present invention. The chair  10  comprises a base  12 , which carries a monocoque structure  14  in which a seat  16  and a backrest  18  are formed as a single panel of injection-molded plastic material essentially in the shape of an L. 
     In the illustrated example, the base  12  has two front legs  20  and two rear legs  22  fixed to each other by an upper structure  24  to which the monocoque structure  14  is fixed. Alternatively, the base  12  could have a rotatable central column. In general, the base  12  can be of any type. 
     The monocoque structure  14  including the seat  16  and the backrest  18  is obtained as a single piece of injection-molded plastic material, for example nylon. The monocoque structure  14  comprises a bellows-shaped deformable transverse band  26 , which extends in the transverse direction between two opposite side edges  28  of the seat  18 . The deformable transverse band  26  is integrally formed with the monocoque structure  14  during the injection-molding step and is formed as one piece with the backrest  18 . The deformable transverse band  26  divides the backrest  18  in the transverse direction into a lower backrest portion  18   a  and an upper backrest portion  18   b . The lower backrest portion  18   a  is connected as a single piece with the rear portion of the seat  16 . 
     The upper backrest portion  18   b  is movable backwards with respect to the lower backrest portion  18   a  between a rest position and a backward-tilted position. The backward movement of the upper backrest portion  18   b  under a backward thrust applied by the user&#39;s back is possible thanks to the elastic deformation of the deformable transverse band  26 . 
     With reference in particular to  FIGS. 3 and 4 , the deformable transverse band  26  comprises a plurality of transverse ribs  30  with C-shaped cross-sections, each of which extends in the transverse direction between the opposite side edges  28  of the backrest  18 . The transverse ribs  30  are connected to each other at their ends and alternately face towards the front part and towards the rear part of the chair. In the example shown, the deformable transverse band  26  comprises three transverse ribs  30 . The upper rib and the lower rib have the respective concave part facing towards the front of the chair and a central rib that joins together the upper rib and the lower rib, and has the concave part facing the rear part of the chair. 
       FIGS. 5 and 6  are longitudinal cross-sections showing the chair  10  in the rest position and in the backward-tilted position, respectively. The deformable portion  26  allows the backward tilt of the upper backrest portion  18   b  relative to the lower backrest portion  18   a . When the backward thrust applied by the user ceases, the deformable transverse band  26  elastically returns to its undeformed position and returns the backrest  18  to the rest position illustrated in  FIG. 5 . The same deformable transverse band  26  also forms a stop which prevents any further backward movement of the upper backrest portion  18   b  beyond the position of maximum backward inclination illustrated in  FIG. 5 . In fact, as shown in  FIG. 6 , when the upper backrest portion  18   b  is tilted backwards, the outer side parts of the bellows-shaped deformable transverse band  26  open, or rather the distance between the transverse ribs  30  increases, while the central part of the deformable transverse band  26  closes, that is, the ribs  30  come into contact with each other. In particular, when the convex parts of the upper rib and the lower rib are compressed into contact with each other, further elastic deformation of the deformable transverse band  26  is prevented. Therefore, in this condition, further backward inclination of the upper backrest portion  18   b  is prevented. 
     In the embodiment illustrated in the figures, the backrest  18  comprises a single deformable transverse band  26 . Alternatively, more deformable transverse bands could be provided, spaced apart in the vertical direction. If the deformable transverse bands are of a number greater than one, they could be distributed along the backrest  18 . 
     It is not strictly necessary that the deformable transverse band  26  extends continuously between the opposite side edges  28  of the backrest  18 . In fact, as shown in  FIG. 7 , the backrest  18  could be provided with a through-opening  32 , which interrupts the deformable transverse band  26  in the transverse direction. The opening  32  visually separates the backrest  18  from the seat  16  and provides a visually lighter chair, with an elastic behavior more easily deducible by the user. 
     Of course, without prejudice to the principle of the invention, the details of construction and the embodiments can be widely varied with respect to those described and illustrated, without thereby departing from the scope of the invention as defined by the claims that follow.