Abstract:
A chair frame ( 10 ) for a stackable chair. The chair frame ( 10 ) includes a seat support ( 12 ) for supporting the seat ( 22 ) of the stackable chair, the seat support ( 12 ) of the frame ( 10 ) defining first and second side frame portions ( 18, 20 ). The chair frame ( 10 ) also includes first and second front leg members ( 24, 26 ) and first and second rear leg members ( 28, 30 ) extending downwardly from the seat support ( 12 ). A back support ( 36 ) is secured to the seat support ( 12 ), the back support ( 36 ) defining first and second side portions ( 38, 40 ) and a lower frame portion ( 44 ) disposed between the first and second side portions ( 38, 40 ) of the back support ( 36 ). Also included are first and second bracing structures ( 46, 48 ) extending between the seat support ( 12 ) and the back support ( 36 ), whereby the bracing structures ( 46, 48 ) strengthen the engagement of the seat support ( 12 ) with the back support ( 36 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not Applicable 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   This invention relates to a chair frame for stackable chairs. More specifically, the present invention is related to a chair frame provided with a bracing system that enhances the durability of the resulting chair without impairing the ease with which chairs utilizing the frame can be stacked, or the stability of the resulting stack of chairs. 
   2. Description of the Related Art 
   Chairs which can be stacked upon one another to facilitate their storage are known in the art. For example, such chairs are disclosed in U.S. Pat. Nos. 3,316,016, 4,057,288, 5,762,396, and 6,174,029 B1. It is desirable that stackable chairs be light weight, such that they can be easily lifted during stacking and unstacking. Therefore, stackable chairs are typically fabricated of light weight tubular metal materials, such as aluminum. However, stackable chairs tend to take a great deal of abuse, particularly while being stacked or unstacked, and such light weight fabricating materials can deform, or otherwise be damaged, such that a chair may not stack properly or be useable for seating. For example, maintenance of the desired angular disposition of the back of a stackable chair relative to the seat portion may be critical to the proper stacking of chairs. Where the back support portion of the chair frame has been bent or deformed, the chair may not properly interlock with the chair stacked above, making stacking impossible, or rendering the resulting stack of chairs unstable. With chairs which are not stackable, bracing structures can easily be added without great concern over the additional weight. However, locating bracing structures on stackable chairs without impairing the ability of the chairs to properly and efficiently interlock for purposes of stacking can be problematic. Moreover, adding extensive bracing structures to the primary components of a stackable chair increases the weight of the chair, such that the ease with which the chairs can be stacked and unstacked can be compromised. 
   In U.S. Pat. No. 3,203,731 a stackable chair having a folding back is disclosed. Because the back portions are folded down over the seat prior to stacking, the need for reinforcing the connection between the back portion and seat portion to insure stackability is obviated, but the hinge mechanism which is required adds cost to the chair. In addition, the relatively thick back portion is folded over the seat portion, fewer chairs can be stacked without the height of the stack becoming untenable. Accordingly, the prior art does not disclose a chair frame which adequately addresses the problem of deformation of, or damage to, the chair frame which undermines the stackability of stackable chairs. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a chair frame for a stackable chair. The chair frame includes a seat support for supporting the seat of the stackable chair, the seat support having first and second side frame portions, a front frame portion and a rear frame portion. The first and second side frame portions extend between the front frame portion and the rear frame portion. The chair frame further includes first and second front leg members, and first and second rear leg members, extending downwardly from the seat support. The first rear leg member is secured to the first outer end portion of the rear frame portion of the seat support, and the second rear leg member is secured to the second outer end portion of the rear frame portion. In this regard, the first outer end portion of the rear frame portion extends outwardly beyond the first side frame portion of the seat support to engage the first rear leg member, and the second outer end portion of the rear frame portion extends outwardly beyond the second side frame portion to engage the second rear leg member. As a result, the rear leg members are outwardly displaced from the points at which the side frame portions of the seat support engage the rear frame portion of the seat support in order to facilitate the stacking of chairs utilizing the chair frame. 
   The chair frame also includes a back support secured to the seat support, the back support having first and second upright side portions and a lower frame portion disposed between the first and second side portions of the back support. In order to strengthen and reinforce the connection between the back support and the seat support, the chair frame includes first and second bracing structures. The first bracing structure is secured at one end to the first side frame portion of the seat support at a point selectively spaced from the point at which the first side frame portion engages the rear frame portion of the seat support, and is secured at the other end to the lower frame portion of the back support. Accordingly, the first bracing structure extends diagonally from the first side frame portion of the seat support to the lower frame portion of the back support. Similarly, the second bracing structure is secured at one end to the second side frame portion of the seat support at a point selectively spaced from the point at which the second side frame portion engages the rear frame portion of the seat support, and is secured at the other end to the lower frame portion of the back support. Thus, the second bracing structure extends diagonally from the second side frame portion of the seat support to the lower frame portion of the back support. The first and second bracing structures provide a bracing system that enhances the durability of the resulting chair without impairing the ease with which the chairs can be stacked, or the stability of the resulting stack of chairs. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which: 
       FIG. 1  is a perspective view of a frame for a stackable chair of the present invention; 
       FIG. 2  is a front elevation view of a chair frame of the present invention; 
       FIG. 3  is a rear elevation view of a chair frame of the present invention; 
       FIG. 4  is a side elevation view of a chair frame of the present invention; 
       FIG. 5  is a top plan view of a chair frame of the present invention; 
       FIG. 6  is a bottom plan view of a chair frame of the present invention; and 
       FIG. 7  is a side elevation view of a plurality of chairs utilizing the chair frame of the present invention which have been placed in a stacked disposition. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A frame for a stackable chair incorporating various features of the present invention is illustrated generally at  10  in the drawings. As is illustrated in  FIG. 7  the chair frame  10  is designed such that chairs incorporating the frame  10  can be stacked, one upon another, to facilitate the storage of a plurality of chairs. As will be discussed in detail below, the chair frame  10  is provided with a bracing system that enhances the durability of the resulting chair without impairing the ease with which the chairs can be stacked, or the stability of the resulting stack of chairs. In the preferred embodiment the chair frame  10  is fabricated of a tubular metal, such as aluminum, but it will be understood that various fabricating materials can be used. For purposes of the discussion herein, the term “chair” is intended to include chairs, benches and stools, as well as other seating structures having legs of various lengths. 
   The chair frame  10  includes a seat support  12  which in the preferred embodiment defines a front frame portion  14 , a rear frame portion  16 , and a pair of oppositely disposed side frame portions  18  and  20  which extend between the front frame portion  14  and the rear frame portion  16 . The seat portion  12  is used to support the seat  22  of a chair utilizing the frame  10 . In this regard, it will be noted that in the preferred embodiment the seat support  12  includes a cross support member  23  which extends between the side frame portions  18  and  20  to support the rear portion of the seat  22 . Whereas the seat support  12  of the chair frame  10  is illustrated as being fabricated of a tubular material which supports the seat  22  proximate its perimeter, it is contemplated that the seat support  12  can define other configurations such as, for example, a platform (not shown) over which a seat cushion is positioned. 
   The chair frame  10  also includes a pair of front legs  24  and  26 , and a pair of rear legs  28  and  30 . In the preferred illustrated embodiment the upper end of the front leg  24  engages the seat support  12  of the frame  10  at the intersection of the front frame portion  14  and the side frame portion  18 , and the upper end of the front leg  26  engages the seat support  12  at the intersection of the front frame portion  14  and the side frame portion  20 . However, it will be noted that the rear frame portion  16  of the seat support  12  extends beyond the side frame portions  18  and  20 , and the outer ends  32  and  34  of the rear frame portion  16  engage the rear legs  28  and  30 , respectively, such that the rear legs  28  and  30  are outwardly displaced from the points at which the side frame portions  18  and  20  intersect the rear frame portion  16 . As a consequence of this construction, and as best illustrated in  FIG. 6 , the width of the seat portion  12  proximate the point at which the side frame portions  18  and  20  engage the rear frame portion  16  is less than the distance between the rear legs  28  and  30 . Thus, as illustrated in  FIG. 6  when a chair incorporating a frame  10 ′ is stacked upon another chair incorporating a frame  10 , the rear legs  28 ′ and  30 ′ of the upper chair are received on either side of the side frame portions  18  and  20  of the lower chair, and in front of the rear legs  28  and  30  of the lower chair, to facilitate the stacking of the chairs. 
   The chair frame  10  of the present invention also includes a back support  36  which defines a pair of upright frame portions  38  and  40  and an upper frame portion  42  and a lower frame portion  44 . In the preferred embodiment the back support  36  is fabricated of a tubular material. However, it is contemplated that the back support  36  could comprise a solid, or substantially solid, panel such that the upper and lower portions of the solid, or substantially solid, panel define the upper frame portion  42  and the lower frame portion  44 , respectively. It will also be noted that in the preferred illustrated embodiment the upright frame portions  38  and  40  are integrally formed with the rear legs  28  and  30 , respectively. However, it will be understood that the upright frame portions  38  and  40 , and the rear legs  28  and  30 , can define separate components. 
   In order to strengthen, and increase the durability of the chair frame  10 , the frame  10  is provided with a pair of bracing structures  46  and  48 . In the preferred embodiment, the bracing structure  46  defines a first end  50  which engages the side frame portion  18  at a point spaced from the point at which the side frame portion  18  engages the rear frame portion  16 , and defines a second end  52  which engages the lower frame portion  44  of the back support  36 . Accordingly, the bracing structure  46  extends diagonally between the side frame portion  18  and the lower frame portion  44  thereby reinforcing the junction of the seat support  12  and back support  36 . Similarly, the bracing structure  48  defines a first end  54  which engages the side frame portion  20  at a point spaced from the point at which the side frame portion  20  engages the rear frame portion  16 , and defines a second end  56  which engages the lower frame portion  44  of the back support  36 . Accordingly, the bracing structure  48  extends diagonally between the side frame portion  20  and the lower frame portion  44  thereby further reinforcing the junction of the seat support  12 , and back support  36 . 
   It will be noted that the second ends  52  and  56 , of the bracing structures  46  and  48  engage the lower frame portion  44  at points inwardly spaced from the upright frame portions  38  and  40 , respectively, such that the bracing structures  46  and  48  serve to reinforce the junction of the seat support  12 , and back support  36 , but do not inhibit chairs incorporating the frame  10  from properly interlocking when the chairs are stacked. Further, in the preferred embodiment, the lower frame portion  44  of the back support  36  is positioned at approximately the same height as the upper surface  58  of the seat  22 . (See  FIG. 4 ) As a consequence, the bracing structures  46  and  48  engage the lower frame portion  44  at approximately the same height as the upper surface  58  of the seat  22 . This construction insures that the bracing structures  46  and  48  do not extend above the seat  22  to the extent that they inhibit the proper stacking of chairs utilizing the frame  10 . 
   As best illustrated in  FIGS. 1 and 3 , the preferred embodiment of the frame  10  is further reinforced by the braces  62  and  64  which extend between the rear frame portion  16  of the seat support  12 , and the lower frame portion  44  of the back support portion  36  proximate the location of the bracing structures  46  and  48 , respectively. It will also be noted that in the preferred embodiment a cross brace  60  is provided which extends between the front legs  24  and  26  to strengthen the legs  24  and  26 . 
   In light of the above, it will be recognized that the chair frame  10  provides a stackable frame which is strong and durable, and which has great advantages over the prior art. The bracing structures  46  and  48  in combination with the braces  62  and  64  significantly reinforce the connection between the seat support  12  of the frame  10  and the seat back  36 . Accordingly, chairs utilizing the frame  10  are less susceptible to being bent out of shape such that they do not properly stack, and are otherwise less susceptible to damage. At the same time, chairs utilizing the frame  10  remain easily and efficiently stackable. 
   While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.