Abstract:
A seat which is mounted between two side frames, each having a horizontal member and vertical leg members, wherein the seat pivots about a transverse torsion bar extending within said seat width; a structural member extending alongside the torsion bar transferring the torsion bar forces to the frames horizontal members, the structural member having travel limiting means thereon to define the pivoting limits of the seat, the torsion bar being rigidly secured at its ends to the seat and rigidly secured at a point within its ends to the structural member.

Description:
DESCRIPTION OF THE PRIOR ART  
         [0001]    Chairs of the abstract description are unknown, but reclining mechanisms seats having torsion bar(s) are common in office-type chairs. When utilizing a torsion bar in an office-type chair, the elongated axis of the bar is usually located above the chair post within a mechanism that also contains the seat rotation stops and the seat initial resiliency controls. Typical office chairs having a torsion bar mechanism are described in U.S. Pat. No. 3,136,580; 3,240,528 and 3,224,807, among others.  
           [0002]    The only four legged chairs known to the applicant that have a torsion bar mechanism, are disclosed in the U.S. Pat. No. 4,938,532 titled “Seating apparatus”, and in the U.S. Pat. No. 5,902,912 titled “Chair with movable back”  
           [0003]    In the chair of U.S. Pat. No. 4,938,532, the torsion bar, its bearings and the back stops are mounted on an aluminum extruded bar that is welded to the chair frame. Here the torsion bar is used to provide a flexible back support, only.  
           [0004]    In the chair of U.S. Pat. No. 5,902,012 the ends of the torsion bar are engaged to the back board rotation limits, while the occupant load is absorbed by the fixed seat horizontal board.  
           [0005]    Here also, the torsion bar is used to provide a flexible back support, only.  
         BACKGROUND OF THE INVENTION  
         [0006]    This patent application is a continuation-in-part of my U.S. Pat. No. 6,168,233 B1, titled “Reclinable seating using a torsion bar”, issued Jan. 2, 2001.  
           [0007]    The present invention relates to seating apparatus which can be in the form of a seat, a chair, sofa or other appliance which is used for seating purposes.  
           [0008]    Here, an inner structure including the bottom seat board and the back board pivots (rotates)—as a unit—within a chair frame. Elastic torsion means allows said inner structure to rotate between established forward and rear positions in relation thereto said chair frame, making the chair more comfortable to users.  
           [0009]    In this invention, a torsion bar is guided and supported by a series of bushings housed inside tubes; in turn the tubes are supported by a flat piece of metal that extends across the width of the chair, attaching the horizontal members of the side frames. An adjustable torsion bar anchor situated about the center of the torsion bar provides the initial resilient torque. All of above elements: the tubes, the bushings and the torsion bar, plus the anchor controls, are placed onto said piece of metal, that will further be referred as the “structural member”.  
           [0010]    What is new is the concept of having four legged (or sled), type chairs having reclinable seating, up to now the exclusive province of office chairs having a reclining mechanism at the top of a center post. But these chairs are too expensive and/or cumbersome to move and to store-away, to be used in high density areas like restaurants, auditoriums, catering halls, etc.  
           [0011]    In view of the shortcomings mentioned above, it is the principal object of the present invention to introduce a chair having a reclinable seat disposed in a four legged frame, or a sled frame, whereby said frame could be made of plastic, metal and/or wood.  
           [0012]    Yet, another object of the invention is to provide an inexpensive reclinable chair having enhanced aesthetics and comfort.  
           [0013]    A further object of the invention is to provide a simplified method of manufacturing and assembling such chairs. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    In the accompanying drawings:  
         [0015]    [0015]FIG. 1 is a perspective view of a four legged reclinable wooden chair according to the present invention,  
         [0016]    [0016]FIG. 2 is a schematic side elevational view of the chair shown in FIG. 1, with the seat in the fully upright position,  
         [0017]    [0017]FIG. 3 is a schematic side elevational view of the chair shown in FIG. 1, with the seat in an fully reclined position,  
         [0018]    [0018]FIG. 4 is an exploded partial perspective view of the seat frame of FIG. 1,  
         [0019]    [0019]FIG. 5 is a schematic sectional view of FIG. 4 taken along line A-A,  
         [0020]    [0020]FIG. 6 is a partial schematic sectional view of FIG. 4 taken along line B-B, with the seat frame in the fully upright position,  
         [0021]    [0021]FIG. 7 is a partial schematic sectional view of FIG. 4 taken along line B-B, showing the seat frame in a fully reclined position,  
         [0022]    [0022]FIG. 8 is a schematic sectional view of FIG. 4 taken along line C-C, showing the torsion bar control mechanism,  
         [0023]    [0023]FIG. 9 is a schematic sectional view of the seat frame of FIG. 2, taken along line D-D, showing another embodiment of the invention,  
         [0024]    [0024]FIG. 10 is a schematic sectional view of the seat frame of FIG. 3, taken along line E-E, showing another embodiment of the invention, 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Referring now in detail to the embodiments of the chair shown in FIG. 1 which comprises a supporting wooden frame incorporating a pair of side frames, each side frame having a substantially horizontal member  12  and substantially vertical leg members  11 . A front cross-rail  13 , and a rear cross-rail  22  connect both side frames in a spaced apart relationship.  
         [0026]    The seat comprises an upholstered bottom board  17 , mounted on the seat frame  14  and an upholstered back board  16 , which are connected to each other at an obtuse angle by the back support  15 . The upholstery consist of contoured foam blocks that are glued onto the bottom and back boards and are subsequently covered by fabrics.  
         [0027]    The seat frame  14  is—usually—an open structure comprising four or more wooden elements, glued and/or nailed together. The seat pivot (rotate) as a unit about a virtual axis T-T, in response to a backward leaning movement of the chair occupant, as shown in FIG. 3.  
         [0028]    It will be understood that the hardware is symmetrically disposed on both side of the chair; hence, the hardware on one side only will be described.  
         [0029]    [0029]FIG. 4 is an exploded perspective view of the chair shown in FIG. 1. Here the chair frame has been vertically displaced from the seat, and for clarity purposes the bottom seat fabric, the foam  29  and the foam support board  30  are not shown.  
         [0030]    The bottom seat board comprises a wooden frame  14 , attached by the back support  15  to the upholstered back  16 .  19  is the tube(s) that houses the square torsion bar  25 , while  24  is a metallic insert to distribute the bar torsion moment over a larger surface of the frame, usually made of soft woods.  20  is a torsion bar rotatable anchor that adjust the initial resilience of the torsion bar, and  21  is the anchor adjusting screw.  
         [0031]    [0031] 18  is the structural member in the shape of a bent metal plate to which the tube  19  is welded; the ends of said member—shown here protruding beyond the frame  14  side—is attached to the underneath of the horizontal members  12 , by means of screws  23 .  
         [0032]    Numeral  35  is a cut out on the seat frame that is necessary for another embodiment of this invention.  
         [0033]    [0033]FIG. 5 shows a cross section of the reclining mechanism. Here the bent structural member  18  is shown fastened to the horizontal members  12  by the fasteners  23 .  
         [0034]    The torsion bar  25  extends within the seat frame  14  and attached to it through the metallic inserts  24 . The torsion bar is held in place by the four plastic bushings  32 , that in turn are housed inside the tubes  19 ; the tubes are welded to the structural member  18 .  
         [0035]    Numeral  20  is the initial torsion bar resilience adjuster.  
         [0036]    [0036] 30  is the foam board, a thin piece of plywood to distribute the load on the foam  29  over the structure of frame  14 .  
         [0037]    In this embodiment, any reclining of the seat is transmitted to both ends of the torsion bar  25  by ways of inserts  24  and frame members  14 .  
         [0038]    The torsion bar would had rotated freely if not for the presence of the adjustable anchor  20  that is mounted firmly on the torsion bar itself; said anchor  20  being rigidly connected to the structural member  18  by the adjusting screw  21 .  
         [0039]    Hence, any seat rotation will twist the ends of the torsion bar that are securely attached to the seat frame  14 , while the center of the torsion bar remains fixed in a desired relationship with the chair side frames. The torsion bar twisting creates the reactive resilience torque that will bias the seat to its upright position.  
         [0040]    The two extreme positions of the seat: fully upright and fully reclined are achieved by limiting the degree of rotation of the seat frame  14 .  
         [0041]    To that effect, a plurality of elastic stops mounted on the structural member  18 , and placed underneath the seat frame  14 , will elastically stop the seat frame rotation at pre-established positions.  
         [0042]    In FIG. 6, 26 is a front stop, a rubber bumper attached to the structural member  18 ; it is placed forward of the torsion bar axis and underneath the seat frame  14 , hence stopping the counter-clockwise rotation of the seat frame at its maximum upright position. Not shown: the tube  19  is solidly welded at some places to the structural member  18 . The word front on the drawing indicates the position of the seat front.  
         [0043]    In FIG. 7, the seat frame  14  is stopped by the rear stop  27 , a rubber bumper that is attached to the structural member  18 ; here the stop prevents the seat frame  14 , and hence the seat, from going farther than a pre-established maximum reclined position.  
         [0044]    [0044]FIG. 8 is a cross-sectional view of the mechanism for adjusting the initial resilience of the torsion bar. Here,  19  is the tube;  25  is the torsion bar that goes through a corresponding opening in the aluminum extrusion of which the anchor  20  is built,  34  is a rotary joint to accommodate the anchor&#39;s different positions in relationship with the member  18 , and  21  is the adjusting screw.  
         [0045]    By tightening up the screw  21 , the torsion bar is twisted counter-clockwise, and the initial resilience increases, biasing the seat harder against the elastic front seat stops  26 . Likewise, any backwards tilting of the seat by an occupant, will only increase the twisting of the bar, further increasing the seat resistance to pivot backwards.  
         [0046]    In another embodiment of the present invention, the seat rotations are limited by the interacting of means disposed in the seat frame with means disposed in the chair side frames. In a wooden chair similar to the one shown in FIG. 2 but having this new embodiment, the seat stops would not be placed on the structural member  18 , that could then be built narrower. To that effect, FIG. 9 is a schematic sectional view of the seat frame of FIG. 2, taken along line D-D, showing this new embodiment in place. Here,  12  is the side frame and  14  is the seat frame.  31  is a narrow ‘L’ shaped metal bracket rigidly attached to the side frame  12  that enters into the opening of the window  35 , a cut out into the seat frame  14  (also, see numeral  35  in FIG. 4), having elastic stops  32  and  33  glued onto the lower and upper walls of the window.  
         [0047]    With the seat at its maximum upright position—as shown in FIG. 2—the seat frame  14  is almost parallel to the side frame  12 , and the bracket  31  is pressed against the upper elastic stop  33 , effectively stopping any further counter clockwise rotation of the seat originated by the torsion bar bias and/or the chair occupant weight.  
         [0048]    [0048]FIG. 10 shows a chair similar to the one shown in FIG. 3 whereby, the reclining seat is stopped at its maximum reclinable position by the bracket  31  acting against the lower elastic stop  32 .