Abstract:
A chair comprising: a metal frame formed by a plurality of tubular metal elements, including a seat portion having two tubular seat support elements and a backrest portion having two tubular backrest support elements extending upwardly from the seat portion, a flexible seat panel of plastic material with high elasticity, having two lateral tubular portions into which respective tubular seat support elements are inserted, and a flexible backrest panel of plastic material with high elasticity having two lateral tubular portions into which respective tubular backrest support elements are inserted, wherein in a rest condition there is a transverse clearance between the outer edges of the lateral tubular portions of the flexible seat panel and of the flexible backrest panel and the respective tubular support elements, and wherein in a deformed condition said transverse clearance is reduced to zero.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of Italian patent application number TO2014A001007, filed Dec. 4, 2014, which is herein incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a chair with elastically-deformable seat and backrest. 
         [0004]    In particular, the invention relates to a chair having a metal frame formed by bent tubular elements that carry a seat panel and a backrest panel. 
         [0005]    2. Description of Prior Art 
         [0006]    As is well known in the field, to increase the comfort, the seat and the backrest should adapt to the weight of the user and to the backward thrust applied by the user&#39;s back. 
         [0007]    One method for adapting the geometry of the chair to the weight of the user and to the backward thrust applied to the backrest envisages the use of “weight-activated” mechanisms with tilting and mutually-synchronized seat and backrest. 
         [0008]    A simpler and cheaper way to adapt the geometry of the chair to the weight of the user and to the backward thrust applied on the backrest is that of producing the seat and the backrest by means of deformable elastic elements, for example, sheets of fabric stretched on lateral supports of the seat and the backrest. These solutions are generally affected by a limited possibility of elastic deformation of the sheets forming the seat and the back. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention aims to provide a chair with a simple structure, characterized by a wide adaptability of the support surfaces of the seat and the backrest. 
         [0010]    According to the present invention, this object is achieved by a chair having the characteristics forming the subject of claim  1 . 
         [0011]    The claims form an integral part of the disclosure provided here in relation to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The present invention will now be described in detail with reference to the attached drawings, given purely by way of non-limiting example, wherein: 
           [0013]      FIG. 1  is a front elevational view of an embodiment of a chair according to the present invention. 
           [0014]      FIG. 2  is a cross-section according to the line II-II of  FIG. 1 . 
           [0015]      FIG. 3  is a cross-section of the part indicated with the arrow III in  FIG. 2 , illustrating the seat in the deformed position. 
           [0016]      FIGS. 4 and 5  are cross-sections according to the arrows IV and V of  FIGS. 2 and 3 , illustrating the seat in the rest position and in the deformed position. 
           [0017]      FIGS. 6 and 7  are enlarged details of the parts indicated by the arrows VI and VII in  FIGS. 4 and 5 . 
           [0018]      FIG. 8  is a perspective view of the backrest indicated by the arrow VIII in  FIG. 1 . 
           [0019]      FIG. 9  is a cross-section on an enlarged scale of the part indicated by the arrow IX in  FIG. 1 . 
           [0020]      FIGS. 10 and 11  are cross-sections according to line X-X of  FIG. 1  in the rest position and in the deformed position, respectively. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    With reference to  FIGS. 1 and 2 , numeral  10  indicates a chair according to a first embodiment of the present invention. The chair  10  comprises a metal frame  12  formed of bent tubular metal elements. The frame  12  includes a seat portion  14  and a backrest portion  16 . The seat portion  14  of the frame  12  comprises two tubular seat support elements  18  oriented longitudinally and parallel to each other along opposite lateral sides of the chair  10 . The backrest portion  16  of the frame  12  comprises two tubular backrest support elements  20  parallel to each other and extending upwardly from the seat portion  14 . The tubular backrest support elements  20  are located on opposite lateral sides of the chair  10 . 
         [0022]    The frame  12  of the chair  10  comprises two front leg elements  22  connected to the front ends of the respective tubular seat support elements  18 . The lower ends of the front leg elements are connected to the front ends of the respective lower longitudinal elements  24 . The rear ends of the lower longitudinal elements  24  are connected to lower ends of the respective rear leg elements  26 . The tubular backrest support elements  20  are formed by upward extensions of the respective rear leg elements  26 . Preferably, the tubular seat support element  18 , the front leg element  22 , the lower longitudinal element  24 , the rear leg element  26  and the tubular backrest support element  20  on each side of the chair  10  are formed by a single bent tubular metal element. The rear end of each tubular seat support element  18  is fixed to the lower end of the respective tubular backrest support element  20 , coinciding with the upper end of the respective rear leg element  26 . 
         [0023]    The two tubular backrest support elements  20  are fixed to respective ends of a rear cross member  28 . The front leg elements  22  are fixed to respective ends of a front cross member  30 . 
         [0024]    The chair  10  comprises a flexible seat panel  32  and a flexible backrest panel  34  formed of molded plastic material with high elasticity. The flexible seat panel  32  and the flexible backrest panel  34  are capable of elastically deforming according to an arcuate shape and of returning to the initial shape when the force causing the deformation ceases. Suitable materials are, for example, nylon and polyoxymethylene (POM). 
         [0025]    The flexible seat panel  32  and the flexible backrest panel  34  have respective lateral tubular portions  36 ,  38 , integrally formed with the respective panels  32 ,  34 . The tubular seat support elements  18  extend through the lateral tubular portions  36  of the flexible seat panel  32 . The tubular backrest support elements  20  have respective upper ends inserted within respective lateral tubular portions  38  of the flexible backrest panel  34 . 
         [0026]    With reference to  FIGS. 2 to 5 , in rest conditions, the flexible seat panel  32  has an essentially flat shape. With reference to  FIGS. 4 and 6 , in rest conditions, in each lateral tubular portion  36  of the flexible seat panel  32  there is a clearance Ps in a transverse direction between the tubular element  18  and the outer edge of the corresponding lateral tubular portion  36 . 
         [0027]    When a user is sitting on the flexible seat panel  32 , the flexible seat panel  32  assumes an arcuate shape as shown in  FIGS. 3 and 5 . The flexible seat panel  32  is elastically deformed to assume the arcuate position. During the elastic deformation of the flexible seat panel  32 , the respective lateral tubular portions  36  move in a direction transverse to the respective tubular support elements  18 , by an amount equal to the respective transverse clearance Ps. In the deformed position of the flexible seat panel  32 , the clearance Ps between the outer edges of the tubular portions  36  and the respective tubular support elements  18  is canceled. When the ends of the lateral tubular portions  36  come into contact with the respective tubular elements  18 , a further deformation of the flexible seat panel  32  is prevented. The clearance Ps between the outer ends of the lateral tubular portions  36  and the respective tubular elements  18  determines the maximum deformation Ds of the flexible seat panel  32 . 
         [0028]      FIGS. 6 and 7  show the detail of the relative movement of the lateral tubular portions  36  with respect to the tubular seat support elements  18 , in the rest position and in the deformed position of the flexible seat panel  32 . 
         [0029]    When the user rises from the chair  10 , the flexible seat panel  32  returns to the undeformed configuration as a result of its elasticity. The lateral tubular portions  36  return to the position illustrated in  FIG. 6  and the lateral clearance Ps returns to the initial value. 
         [0030]    In the illustrated example, the clearance Ps of the lateral tubular portions  36  is essentially constant along the longitudinal axis of the respective tubular seat support element  18 . Consequently, the maximum deformation Ds of the flexible seat panel  32  is essentially constant along the central axis of the flexible seat panel  32 . 
         [0031]    Alternatively, the clearance Ps, the ends of the lateral tubular portions  36  and the respective tubular elements  18  could vary along the axis of the respective tubular element  18 , from a minimum value level with the front end of the flexible seat panel  32 , and a maximum value level with the rear end of the flexible seat panel  32 . In this way, in the conditions of use, the deformation of the seat panel has a minimum value at the front edge of the seat panel  32  and a maximum value at the rear edge of the seat panel  32 . Thus, in the deformed position, the central axis of the seat panel  32  inclines backwards with respect to the undeformed position. The backward inclination of the flexible seat panel  32  has a similar effect to that of chairs with seats hinged to the fixed structure about a transverse axis. 
         [0032]    With reference to  FIGS. 8-11 , the flexible backrest panel  34  has a lower edge  40  and an upper edge  42 . In the example shown, the lateral tubular portions  38  of the flexible backrest panel  34  have lower ends aligned with the lower edge  40  and upper ends located lower than the upper edge  42 . Two notches  44  curving inwardly from the respective outer edges of the flexible backrest panel  34  are arranged immediately above the upper ends of the lateral tubular portions  38 . The flexible backrest panel is preferably provided with vertical ribs  46  parallel to each other and protruding from the front surface of the flexible backrest panel  34 . 
         [0033]    The lateral tubular portions  38  of the flexible backrest panel  34  have transverse through-cuts  48  spaced apart in the vertical direction. Each cut  48  forms an empty space in the wall of the respective lateral tubular portion  38 , contained in a plane orthogonal to the longitudinal axis of the respective lateral tubular portion  38 . The through-cuts converge on respective through-holes  50  formed along the inner edges of the respective lateral tubular portions  38 . 
         [0034]    With reference to  FIG. 10 , in the rest condition, a clearance Pb in a transverse direction is provided between the outer edges of the lateral tubular portions  38  of the flexible backrest panel  34  and the respective lateral tubular elements  20 . 
         [0035]    With reference to  FIG. 9 , the transverse clearance Pb of the lateral tubular portions  38  varies along a vertical direction, from a minimum value Pb′ level with the lower edge  40  of the flexible backrest panel  34 , to a maximum value Pb″ level with the upper edge of the lateral tubular portion  38 . 
         [0036]    In the rest condition ( FIG. 10 ), the flexible backrest panel has an arcuate shape. When a user leans back against the flexible backrest panel, it is elastically deformed, as shown in  FIG. 11 . The radius of curvature of the flexible backrest panel decreases. During the elastic deformation of the flexible backrest panel  34 , the respective lateral tubular portions  38  move in a transverse direction with respect to the respective tubular support elements  18 , by an amount equal to the respective transverse clearance Pb. In the deformed position of the flexible seat panel  32 , the clearance Pb between the outer edges of the tubular portions  38  and the respective tubular support elements  20  is canceled, as shown in  FIG. 11 . When the outer edges of the lateral tubular portions  38  come into contact with the respective tubular elements  20 , a further deformation of the flexible backrest panel  34  is prevented. The clearance Pb between the outer edges of the lateral tubular portions  38  and the respective tubular elements  20  determines the maximum deformation of the flexible backrest panel  34 . Given that the clearance Pb varies in the vertical direction, the maximum deformation of the flexible backrest panel  38  is greater for areas closest to the upper edge  42  and lower for areas closest to the lower edge  40 . Consequently, in the deformed position, the backrest inclines backwards with respect to the rest position by an angle a, as shown in  FIG. 2 , where the continuous line indicates the rest position and the dotted line indicates the deformed position of the flexible backrest panel. The backward inclination of the backrest has a similar effect to that of chairs with tilting backrests articulated about a transverse axis. The through-cuts  48  serve to enable a differentiated deformation of the various transversal portions of the flexible backrest panel. 
         [0037]    The flexible backrest panel is subject to an elastic return force which tends to return it to the undeformed position. This elastic force applies a thrust on the back of the user, in a manner similar to the elastic mechanisms of chairs with tilting seats. When the backward thrust applied by the user ceases, the backrest returns to its rest position illustrated in  FIG. 10 . 
         [0038]    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.