Abstract:
A chair comprising: a support structure including a rigid front fixing element, and an essentially L-shaped seating element, including a seat portion and a backrest portion connected to each other via an arcuate connecting portion, wherein the seat portion comprises a front fixing section fixed to said rigid front fixing element, a main seat section having a concave cross-section and a planar bending section located between said front fixing section and said main seat section and having a flat cross-section.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of Italian patent application number 102015000022850, filed Jun. 11, 2015, which is herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The present invention relates to a chair comprising a support structure and a flexible seating element capable of deforming elastically backwards under the user&#39;s weight. 
       Description of Prior Art 
       [0003]    In the state of the art, chairs equipped with an elastically deformable backrest capable of assuming a rest position and a backwardly inclined position are very widespread. Simpler chairs have the seat fixed and the backrest elastically inclinable backwards. Chairs are also known, typically office chairs, provided with mechanisms that synchronize the tilting movement of the seat and the backrest to generate the required comfort. Chairs of this type offer a high comfort due to the synchronized movement of the seat and of the backrest, but have the drawback of a greater complexity due to the mechanism that synchronizes the movements of the seat and the backrest. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention aims to provide a chair devoid of mechanisms and that offers characteristics of comfort comparable to those of traditional chairs with synchronized seat and backrest. 
         [0005]    According to the present invention, this object is achieved by a chair having the characteristics forming the subject of claim  1 . 
         [0006]    The claims form an integral part of the disclosure provided here in relation to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein: 
           [0008]      FIG. 1  is a perspective view of a chair according to the present invention. 
           [0009]      FIG. 2  is a perspective view of the part indicated by the arrow II in  FIG. 1 . 
           [0010]      FIG. 3  is a side view of the chair of  FIG. 1 . 
           [0011]      FIGS. 4, 5, 6, 7 and 8  are sections according to the lines IV-IV, V-V, VI-VI, VII-VII and VIII-VIII of  FIG. 3 , respectively. 
           [0012]      FIG. 9  is a side view illustrating the chair of  FIG. 1  in a rest position and in a backwardly inclined position. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    With reference to the figures, numeral  10  designates a chair according to the present invention. The chair  10  comprises a base structure  12  and a seating element  14  fixed to the base structure  12 . In the illustrated example, the base structure  12  comprises a central column  16  rotatable about a vertical axis, carried by a plurality of arms  18  equipped at their ends with pivoting wheels  20 . A base structure of this type is not, however, mandatory and can be replaced by base structures of different kinds depending on requirements. For example, the chair according to the present invention can be provided with a base structure with four legs or with a cantilever frame. 
         [0014]    A rigid fixing element  22  is fixed to the upper end of the rotatable column  16 . The rigid fixing element  22  is preferably made of metal, for example, a light die-cast alloy, and comprises—in one piece—a hub  24  fixed to the central column  16 , two arms  26  that extend in a cantilevered manner from the hub  24  in a generally V-shaped configuration and a front plate  28 , which joins together the outer ends of the arms  26 . Alternatively, the rigid fixing element  22  can have a single arm  26 , in a central position with respect to the front plate  28  according to a general T-shaped configuration. The front plate  28  is spaced apart in the horizontal direction with respect to the vertical axis of the rotatable column  16 . With reference to  FIGS. 3 and 9 , the arms  26  extend upwardly starting from the hub  24 , so that the front plate  28  is located at a greater height with respect to the upper end of the central column  16 . 
         [0015]    The seating element  14  is essentially L-shaped and is preferably formed of a single piece of injection-molded plastic material. Preferably, the seating element  14  is made of compact polyurethane. This material has different mechanical characteristics from the plastic materials commonly used in the sector of chairs and, in particular, proves very effective for designing elements with cross-sections of reduced dimensions, but with high rigidity and excellent elastic memory. The seating element  14  may be produced using other plastic materials with good elastic memory, such as, for example, nylon or the like. 
         [0016]    The seating element  14  comprises a seat portion  30  and a backrest portion  32 , connected together by an arcuate connecting portion  34 . The arcuate connecting portion  34  has an upper portion integral with a lower portion of the backrest portion  32  and a lower portion integral with a rear portion of the seat portion  30 . 
         [0017]    The seat portion  30  is, in turn, subdivided into three sections: a front fixing section  30   a,  a planar bending section  30   b  and a main section  30   c.  The front fixing section  30   a  rests on the upper surface of the front wall  28  of the rigid fixing element  22  and is fixed to the rigid fixing element  22  by means of screws  36  ( FIG. 2 ). The planar bending section  30   b  extends transversely and is positioned in the longitudinal direction between the front fixing section  30   a  and the main seat section  30   c.  With reference to  FIGS. 3 to 5 , the planar bending section  30   b  is slightly spaced apart in the vertical direction from the arms  26  of the rigid fixing element  22 . The central seat section  30   c  is widely spaced apart in the vertical direction from the arms  26  and from the hub  24  of the rigid fixing element  22 . 
         [0018]    With reference to  FIGS. 4 to 6 , in a cross section, the planar bending section  30   b  of the seat portion  30  is flat. More precisely, in cross-section, the planar bending section  30   b  has a thin profile with two main flat walls parallel to each other ( FIG. 4 ). With reference to  FIGS. 5 and 6 , in cross-section, the main seat section  30   c  has a concave shape. More precisely, in cross-section the main seat section  30   c  has a flattened shape with two curved main walls with their respective concavities facing upwards. 
         [0019]    The planar bending section  30   b  has a much lower bending rigidity than that of the main seat section  30   c,  so that the seating element  14  can flex around a transverse axis passing through the planar bending section  30   b.  The concave shape of the main seat section  30   c  makes the seating element  14  much more rigid and essentially non-deformable by bending at the main seat section  30   c.    
         [0020]    With reference to  FIG. 8 , the backrest portion  32  has a concave shape with the concavity facing forwards. More precisely, in cross-section, the backrest portion  32  has a thin profile with two main curved walls with the respective concavities facing forwards. Preferably, the arcuate connecting portion  34  has a flat shape in cross-section, with two main walls parallel to each other. In this way, the backrest portion  32  can flex backwards with respect to the seat portion  30  since the flat shape in cross-section of the arcuate connecting portion  34  has a low bending rigidity. The backrest portion  32  is instead essentially non-deformable by bending because the concave cross-section has a high bending rigidity. 
         [0021]    Ergonomic studies have shown that the comfort of a chair increases as the fulcrum of tilting of the seat is advanced, ideally in close proximity to the user&#39;s knees. In the solution according to the present invention, the transverse tilting axis of the seat portion  30  is at the planar bending section  30   b,  which is immediately adjacent to the front fixing portion  30   a.  Therefore, the tilting axis of the seat portion  30  is in a very advanced position, which is advantageous for the comfort of the tilting movement of the seat portion  30 . The main seat section  30   c  has a concave cross-section between the planar bending section  30   b  and the arcuate connecting portion  34 . This concavity is ergonomically functional to the seating comfort and makes this part of the seat portion  30  practically non-deformable by bending. 
         [0022]    The arcuate connecting portion  34  has a flat cross-section and therefore has a low bending rigidity. This allows the obtainment of a bending zone of the backrest portion  32  in an ergonomically favorable area, next to the hips of the user. The backrest portion  32  has a concave cross-section, which makes the backrest more comfortable for supporting the user&#39;s back and at the same time increases the bending rigidity of the backrest portion  32  and minimizes the elastic deformation. 
         [0023]      FIG. 9  shows the seating element  14  of the chair according to the present invention with the rest position marked by a continuous line and the deformed position marked with a dotted line. It can be noted that the elastic deformation of the seating element  14  is given by the sum of the bending deformation of the seat portion  30  around the planar bending section  30   b  and of the elastic deformation of the arcuate connecting portion  34 . The seating element  14  returns to the rest position when the backward thrust applied by the user ceases, thanks to the elastic characteristics of the material. 
         [0024]    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.