Abstract:
A chair comprising a support structure bearing a seat and a backrest, in which the backrest comprises a bearing portion and a connecting portion for connection to the support structure, in which the backrest is tiltable rearwards relative to a resting position under a rearwards thrust applied by the user and elastically returns to the resting position when the rearwards thrust ceases. The rearwards tilting of the backrest is formed in part by an elastic deformation of the bearing portion and in part by a displacement of at least a part of the connecting portion relative to the support structure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of European Patent Application serial number 04424044.7, filed Jan. 26, 2004, 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 a rearwards tiltable backrest under a rearwards thrust applied by the user.  
         [0004]     2. Description of the Related Art  
         [0005]     Very many types of chairs are known in which the backrest is tiltable rearwards and elastically returns to a resting position when the rearwards thrust applied by the user ceases. In most cases, the backrest is associated to a complex elastic return mechanism, provided with a high number of components.  
       SUMMARY OF THE INVENTION  
       [0006]     The object of the present invention is to provide a chair with tiltable backrest which is simple, comfortable and composed by a reduced number of components that can be assembled in simple and rapid fashion.  
         [0007]     According to the present invention, said object is achieved by a chair having the characteristics set out in claim  1 . 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The features and the advantages of the chair according to the present invention shall become readily apparent from the detailed description that follows, provided purely by way of non limiting example, with reference to the accompanying drawings, in which:  
         [0009]      FIG. 1  is a perspective view of a first embodiment of a chair according to the present invention,  
         [0010]      FIG. 2  is a partial lateral, and partially sectioned, view of the chair of  FIG. 1 ,  
         [0011]      FIG. 3  is a partial section according to the line III-III of  FIG. 1 ,  
         [0012]      FIG. 4  is an exploded perspective view of the part designated by the arrow IV in  FIG. 1 ,  
         [0013]      FIG. 5  is a perspective view of a second embodiment of a chair according to the present invention,  
         [0014]      FIG. 6  is a partial lateral view of the chair of  FIG. 5 ,  
         [0015]      FIG. 7  is a partial plan view, partially sectioned according to the arrow VII of  FIG. 5 ,  
         [0016]      FIGS. 8 and 9  are partial sections according to the lines VIII-VIII and IX-IX of  FIG. 7 ,  
         [0017]      FIG. 10  is an exploded perspective view of the part designated by the arrow X in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0018]     With reference to  FIG. 1 , the number  10  designates a perspective view of a first embodiment of a chair according to the present invention. The chair  10  comprises a support structure  12  which bears a seat  14  and a backrest  16 . The support structure  12  comprises, on each side of the chair, a metallic support  18  with a substantially inverted U shape, having an upper part  20 , a forward inclined branch  22  forming a front leg and a rearward inclined branch  24  forming a rear leg.  
         [0019]     With reference in particular to  FIG. 4 , the support structure  12  comprises two transverse elements  26  whose ends are fastened, for instance by welding, to the bent supports  18  forming the front legs  22  and rear legs  24  of the chair  10 .  
         [0020]     With reference to  FIG. 4 , the support structure  12  further comprises, on each side of the chair, a box element  28  fastened between the ends of the transverse elements  26 . In the embodiment illustrated in the Figures, the box element  28  comprises a base element  30  made of bent metal plate with a substantially channel shaped cross section, fastened to the base structure  12 . For example, the base element  30  can be fastened by welding to the two transverse elements  26 . The box element  28  comprises a closing element  32  fastened to the base element  30  and positioned to close the open upper side of the base element  30 , in such a way as to form a closed box structure.  
         [0021]     The base element  30  has an outer lateral wall  34 , a bottom wall  36  and an inner lateral wall  38 . The inner lateral wall  38  has a bent edge  40  provided with holes  42  with vertical axis. The two lateral walls  34 ,  38  are provided with two aligned holes  44  with horizontal axis.  
         [0022]     The closing element  32  has a wall  36  facing the bottom wall  36  of the base element  30 . The wall  46  has two holes  48  aligned to two holes  50  formed in the bottom wall  36  of the base element  30 . The wall  46  has a bent edge  52  located close to the bent edge  40  of the base element  30 . The closing element  32  is fastened to the base element by means of screws  54  which extend through aligned holes of the bent edges  40 ,  52  and which engage respective nuts  56 .  
         [0023]     The seat  14  is preferably constituted by a monolithic element made of plastic material, injection moulded and fastened to the support structure  12 . In the example illustrated in  FIGS. 1 through 4 , the seat  14  is fastened to the bent edges  40 ,  52  of the two box elements  28 , for instance by means of self-threading screws  58  which extend through holes of the bent edges  40 ,  52  and engage seats  60  integrally formed on the lower surface of the seat  14 . Alternatively, the seat  14  could be fastened to a different component of the support structure  12 , for instance to the transverse elements  26 . As a further alternative, the seat could be movable relative to the base structure  12 . For example, the seat could be oscillating relative to the base structure  12  around a transverse axis.  
         [0024]     The backrest  16  comprises a bearing portion  62 , preferably constituted by injection moulded plastic material, having a non planar bearing surface  64  against which bears the user&#39;s back. The backrest  16  comprises two connecting elements  66  which connect the bearing portion  62  of the backrest  16  to the support structure  12 .  
         [0025]     Each connecting element  66  is formed by a monolithic body, preferably constituted by metallic material, for example made of steel, aluminium or light alloy. Each connecting element  66  has a stem  68  which extends rearwards relative to the articulation pivot pin  72  and which is inserted with slight interference into a corresponding lateral seat of the bearing portion  62 , so that the two connecting elements  66  are fixed relative to the bearing portion  62  of the backrest  16 .  
         [0026]     With reference in particular to  FIG. 4 , each connecting element  66  has a reaction portion  70  which extends forwards relative to the articulation pivot pin  72  and is housed within the corresponding box element  28 . The reaction portion  70  is articulated to the base element  30  around a transverse axis by means of a pivot pin  72  which engages the holes  44  of the lateral walls  34 ,  38  and a hole  74  of the reaction portion  70 .  
         [0027]     Each connecting element  66  is subject to the action of elastic means which tend to maintain the backrest  16  in a resting position and which contrast a rearwards thrust applied by the user against the bearing surface  64  of the backrest  16 . In the embodiment illustrated by way of example in the figures, the elastic means are formed by two helical compression springs  76  interposed between the closing element  32  and the reaction portion  70 . The springs  76  are housed within respective seats  78  of the reaction portion  70  and bear against the bottom walls of said seats. Preferably, within the springs  76  extend respective pivot pins  78  fastened between the wall  46  of the closing element  32  and the bottom wall  36  of the base element  30 . The pivot pins  78  extend through the holes  48  of the wall  46  and are engaged by screws  80  which extend through the holes  50  of the bottom wall  36 . As shown in  FIG. 3 , the pivot pins  78  extend with play through respective holes  82  formed in the bottom walls of the seats  78  of the reaction portion  70 .  
         [0028]     As shown in  FIG. 4 , each connecting element  66  is also provided on a lower surface thereof with a notch  84  which abuts against the rear transverse element  26  to form an end stop for the rearwards oscillation of the connecting element  66 .  
         [0029]     With reference to  FIGS. 1 through 3 , the bearing surface  64  of the backrest  16  has an arched shape with vertical generatrices. A backrest with this shape would be substantially non deformable relative to a transverse axis. The bearing surface  64  is provided with one or more weakened area  86  whose purpose is to make elastically deformable the bearing portion  62  of the backrest  16 . In the illustrated example, the weakened areas extend in the transverse direction through the bearing surface  64 . However, the weakened areas could have a different orientation relative to the transverse direction.  
         [0030]     The or each weakened area  86  can be constituted by a through notch or by a groove with reduced thickness relative to the remaining part of the bearing portion  62 . In the example illustrated in the figures, the bearing portion  62  of the backrest  16  is provided with three mutually parallel weakened areas  86 , each of which is shaped as a transverse line which extends substantially over the whole width of the bearing surface  64  with the exception of the lateral edges of the backrest  16 . The number of the weakened areas  86  may naturally vary according to the applications.  
         [0031]     The three weakened areas  86  subdivide the bearing portion  62  of the backrest  16  into four sections: a lower section  88 , two intermediate sections  90  and an upper section  92 . Each weakened area  86  forms a hinge which allows a relative inclination between adjacent backrest sections. Each weakened area allows an elastic deformation of the bearing portion  62  under the action of a rearward thrust applied by the user, so that the bearing portion  62  as a whole can be deformed as shown with dashed and dotted line in  FIG. 2  relative to the non deformed configuration illustrated in the same figure with continuous line. When the rearwards thrust on the bearing portion  62  cease, the backrest sections  88 ,  90 ,  92  go back to their non deformed configuration thanks to the elastic return of the material.  
         [0032]     Each weakened area  86  is intrinsically provided with an arrest which limits the maximum angle of relative inclination between the adjacent backrest sections. As shown in  FIG. 2 , the maximum angle of relative inclination between two adjacent backrest sections is defined by the condition in which the rear edges of each weakened area  86  come in contact with each other. The height of each weakened area  86  therefore defines the maximum angle of rearwards inclination between the adjacent backrest sections.  
         [0033]     In use, the backrest  16  is capable of tilting rearwards under the action of a thrust applied by the user. A part of the rearwards inclination of the backrest  16  is due to an oscillating motion of the connecting elements  66  relative to the support structure  12  around the axes of the pivot pins  72 . Another part of the rearwards tilting motion of the backrest  16  is due to the deformation of the bearing portion  62  of the backrest  16 . The oscillating motion of the bearing elements  66  is contrasted by the action of the springs  76  whilst the deformation of the bearing portion  62  is contrasted by the elasticity of the material. In a practical embodiment, the two components of the tilting motion of the backrest  16  have substantially the same amplitude, for instance the rearwards inclination of the bearing elements  66  allows an inclination of the backrest by about 9° and the deformation due to the relative inclination of the backrest sections  88 ,  90 ,  92  allows an additional inclination of about 9°. The combination of these two motions (inclination of the backrest  16  and deformation of the bearing portion  62  of the backrest  16 ) allows to obtain ideal conditions of comfort for the user.  
         [0034]      FIGS. 5 through 10  show a second embodiment of a chair according to the present invention. The details corresponding to those described above are designated by the same numeric references.  
         [0035]     In this variant of the invention, the connecting elements  66  of the backrest  16  are integrally formed with the remaining part of the backrest  16  and are fastened to the support structure  12  instead of being oscillating relative to the support structure as in the previously described variation. The connecting elements  66  are elastically yielding and allow an inclination of the backrest by effect of an elastic deformation of a part thereof.  
         [0036]     With reference in particular to  FIG. 10 , the support structure  12  of the chair comprises two transverse elements  26  which are fastened at each of their ends to the upper part  20  of the corresponding support  18 . In the illustrated example, transverse elements  26  are fastened to the supports  18  by means of horizontal screws  100  which extend through holes  102  of the upper part  20  of each support  18  and engage threaded holes  104  formed at the ends of the transverse elements  26 .  
         [0037]     With reference again to  FIG. 10 , the support structure  12  comprises, on each side of the chair, a support element  106  fastened, for instance by means of welding, to the transverse elements  26 . The seat  14  is fastened to the support elements  106  by means of screws  108 .  
         [0038]     The backrest  16 , has at the two sides of the bearing surface  64 , two relatively rigid  110  uprights preferably obtained in monolithic form with the remaining part of the bearing surface  64  by moulding of plastic material. Each upright  110  has a lower integral portion bent forwards in substantially L shape, forming a connecting element  66  for connecting the backrest  16  to the support structure  12 .  
         [0039]     With reference in particular to  FIG. 10 , each connecting element  66  has a horizontal fastening portion  112  which is joined to a corresponding upright  110  by an elastically yielding area  114 . The horizontal fastening portion  112  of each connecting element  66  is fastened to the upper part  20  of the corresponding support  18 . Preferably, said fastening is obtained by means of a pair of horizontal pivot pins  116  each of which engages a hole  118  of the horizontal fastening portion  112  and a hole  120  of the upper part  20  of the support  18  (see also  FIG. 9 ).  
         [0040]     As shown in  FIG. 6 , the elastically yielding junction portion  114  of each connecting element  66  allows a rearwards inclination of the respective upright  110  under the action of a rearwards thrust applied by the user on the backrest  16 . The elastically deformable portion  114  has a lower surface  122  which is destined to come in arresting contact against the rear transverse element  26  to limit the rearwards inclination travel of the backrest  16 .  
         [0041]     As in the previously described embodiment, the bearing portion  62  of the backrest  16  is provided with weakened areas  86  which allow an elastic deformation of the bearing surface  64  as shown with dashed and dotted line in  FIG. 6 . As shown in  FIG. 5 , in this second embodiment the weakened areas  86  are formed by a plurality of transverse lines interrupted at the central part of the backrest, to leave a central area  124  of the bearing surface  64  that is not traversed by the weakened areas  86 . The manner whereby the bearing portion  62  of the backrest  16  is deformed under the rearwards thrust applied by the user is identical to the one described previously. The presence of the central area  124  lacking weakened areas makes the bearing portion  62  stiffer.  
         [0042]     From  FIGS. 1 and 5  it is readily apparent that the structure of the chair  10  allows the vertical superposition of multiple chairs of the same type. The means which allow the rearwards inclination of the backrest  16  have very limited bulk in the vertical direction and do not limit the vertical superposition of the chairs in any way.  
         [0043]     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.