Abstract:
An upholstered patio chair having a metal frame structure of compound three-dimensional shape with at least one internal hollow channel extending along the length of the frame structure and an elongated groove located in the frame structure opening into the hollow channel and forming a lip portion in the frame structure. At least one fabric panel for upholstering the frame which includes an edge containing a loop which extends through the elongated groove and into the hollow channel of the frame structure. An elongated wedge member secures the edge of the fabric panel to the frame structure in the channel by creating an interference fit between the wedge member and the lip portion of the frame structure.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to outdoor patio furniture and, more particularly to a technique for upholstering a chair comprising a welded extruded metal frame and an upholstery material fabric attached to the frame so the fabric material is kept in tension as the material is assembled onto a compound contour of the frame.  
         BACKGROUND OF THE INVENTION  
         [0002]    Outdoor patio furniture has become a highly competitive market in which manufacturers are always looking for ideas that cut down on manufacturing costs and time, as well as providing a superior product. The present invention is a retention method for a fabric seating material that is captured along the complete perimeter of a chair frame. Because patio furniture is designed to remain outdoors, typically the furniture is constructed of metal or plastic. Plastic has proven to be an undesirable material because it tends to have a short service life. Metal, on the other hand, is more desirable in that it is able to withstand the elements and lasts for generations.  
           [0003]    A problem with metal outdoor patio furniture is that it can be uncomfortable to be seated on for an extended length of time, unless the seating surfaces are designed properly. Typically, when people are using patio furniture, it is during a time of leisure and therefore a comfortable seating surface is desirable.  
           [0004]    Manufacturers of metal outdoor furniture have designed the furniture to incorporate cushions to make the furniture more comfortable. However, cushions can be inconvenient because they must be stored indoors to protect them from the elements such as rain and prolonged sun exposure. Not only is it inconvenient to remove the cushions after each use, but cushions themselves can require additional storage space when not in use.  
           [0005]    Recognizing the problems associated with metal outdoor patio furniture and the problems created by the use of cushions, manufacturers have looked for a way to upholster patio chairs with a material that is comfortable yet will not require its removal and storage when not in use. It has become apparent that a woven synthetic fabric is an ideal material for use with outdoor metal patio furniture. This material possesses qualities of providing a comfortable seating surface while being water resistant and therefore able to withstand the outdoor environment.  
           [0006]    A problem faced by manufacturers of outdoor patio furniture is how to attach the synthetic fabric to a metal frame structure. The material has to be secured to the frame in such a way that it provides a seating and back surface strong enough to support the user while providing a comfortable surface. Use of fasteners such as staples or rivets is not necessarily desirable or practical for certain types of metal frame outdoor patio furniture.  
           [0007]    The patio furniture industry has in recent years used a method for attaching woven synthetic fabric to a metal frame structure which has proved to be highly successful. This technique includes the step of folding over the edges of the fabric and stitching the edge down to form a loop along opposite sides of the fabric. These loops are then attached to the sides of the frame structure by inserting them in a groove along the surface of the hollow frame, such that the loop extends through the center of a hollow channel in the frame members. A flexible plastic rod having a diameter larger than the width of the groove is threaded through the channel and the loop within the frame, thereby securing the fabric to the frame members along its entire length. This technique has been used to secure fabric to the seating surface as well as the back surface of the chair. It is recognized that this technique provides a reasonably comfortable seating surface, however, this method has been limited to use on chairs having simple two dimensional seating and back surfaces. Considering that prior seating attachment design relies on a frame having a slot with a fixed width that is smaller than the size of the rod, requires that the fabric hem be inserted into the slot first without the rod and then the rod must be passed through an opening at the end of the frame through the hem. This method requires the fabric to be in a non-tension condition during assembly and other mechanical means are needed to spread the frame in such a way as to put tension in the fabric.  
           [0008]    It has also been recognized that outdoor patio furniture could be even more comfortable if designed to incorporate a compound three-dimensional contour, thereby conforming better to the contours of the human body. A compound surface is created by changing the direction of the fabric in a third dimension, for example, by covering the frame at the third and fourth sides. Additionally, chairs incorporating such a compound three-dimensional contour can be aesthetically more appealing. Thus, there exists a need for a method for upholstering outdoor patio furniture which incorporates compound three-dimensional contours and eliminates the problems with previous fabric retention methods.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides an upholstered outdoor patio seating furniture having compound three-dimensional contours and a retention method for the flexible seating material. The patio chair and retention method of the present invention result in a strong design to hold the fabric in place under high tension, is easy to install in the frame, and is able to provide a flexible seating surface on a compound frame structure which results in an appearance that the flexible seating is an integral part of the frame. This invention facilitates a full perimeter fabric attachment since side openings are not needed to insert a rod and tensioning hardware is not needed. Tensioning methods for four sides would be very complex and costly with previous methods and are eliminated by the present invention.  
           [0010]    In one embodiment, the chair comprises a rigid metal frame structure in which frame members are preferably made of extruded metal having a cross-section which includes one or more internal cavities extending lengthwise along the frame member. The frame members are assembled in a desired design configuration to form a frame structure enclosed on all sides and defining the contours of a right side, a left side, a back surface and a seating surface. One or more of each side surface, back surface and seating surface is formed such that a compound three-dimensional contour for the chair is created by the fabric.  
           [0011]    Each section of the frame to which the flexible seating material is to be attached includes a groove in the frame which extends into the hollow interior of the cross-sectional structure of the frame member. This groove is used to attach the flexible material to the frame structure. An elongated narrow loop is formed along edges of the fabric seating surface which is to be attached to the frame member. Plastic rods are then inserted into the loop formed along the edges of the fabric panel. The loop containing the plastic rod is then inserted into the groove in the frame followed by an elongated molded strip that creates a wedge to trap the fabric and the rod inside the frame. The molded strip that contains the wedge forms an outer surface of the groove once it is inserted into the frame. The slot opening formed by the wedge and the frame is smaller than the rod and therefore the fabric cannot come out unless the wedge is removed. The wedge is locked in place by an interference created by a lip in the wedge and an undercut molded into the frame.  
           [0012]    The assembly process starts by first installing the rod into the fabric hem, then inserting an edge of the fabric into the frame and immediately followed by pushing the wedge behind the fabric. This process is performed in a sequential manner along the perimeter of the frame until all of the fabric is trapped in the frame. The wedge has a tendency to snap into the frame as the wedge strip registers into the slot. Additional space in the interior of the frame provides room for the rod to move aside as the wedge is pushed into the slot as it registers in place.  
           [0013]    The retention method of the present invention has a self-locking feature in that the greater the tension on the fabric, the greater the force holding the wedge in the frame. The force created by the rod attempting to come out of the slot pushes laterally against the wedge in a manner that increases the interference between the wedge lip and the frame undercut. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a perspective view of an upholstered chair according the principles of the present invention; and  
         [0015]    [0015]FIG. 2 is a cross-sectional view of the frame structure showing the retention method of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring the drawings, FIG. 1 illustrates one example of an upholstered outdoor patio chair  10  constructed in accordance with the principles of this invention. The chair consists of a metal frame structure  12  to which a woven synthetic material  14  is attached. Other common upholstery fabric materials can also be used. The chair frame structure comprises a plurality of sections. A first frame member  16  begins at a first ground engaging end  18  and extends vertically to form the left front leg  20  of the chair. The first frame section continues then having a first bend and extends rearwardly forming the left arm rest  22 . The first frame section continues and is bent downwardly to a second grounding engaging end  24  to form the left rear leg  26 . A second frame member  28  begins at a third ground engaging end  30  and extends vertically to form the right front leg  32  of the chair. The second frame section continues, then having a first bend and extends rearwardly forming the right arm rest  34 . The second frame section continues and is bent downwardly to a fourth ground engaging end  36  to form the right rear leg  38 . Horizontal front support member  40  extends between and is welded to the left and right front legs. Horizontal lower back support member  42  extends between and is welded to the back legs. A second horizontal upper back support member  44  extends between the rear of the left and right arm rests for further support.  
         [0017]    Finally, the frame structure consists of a seating surface frame member  46  which comprises a left side  48 , a right side  50  and top and bottom sides  52  and  54  respectively. The seating surface frame member  46  is attached between the first frame section  16  and the second frame section  28 . Although chair  10  is depicted with a particular design, it is to be understood that the chair can comprise many different designs.  
         [0018]    Preferably the entire frame structure, but at least the frame structure to which flexible seating material is to be connected comprises a continuous configuration preferably made of any aluminum extrusion with three internal hollow channels spaced apart and running parallel throughout the entire length of the sections as seen best in FIG. 2. The frame section  12  includes internal hollow channels  60 ,  62  and  64 . Channel  60  and  62  is divided by support member  66  and channels  62  and  64  are divided by support member  68 . Support members  66  and  68  extend from an outer surface  70  and an opposite outer surface  72  of the frame member  12 . The hollow channels provide the frame section with a light weight feature along with greater flexibility. Channel  64  has a slot  78  molded on one surface. Slot or groove  78  is formed as part of the extension.  
         [0019]    The chair frame is upholstered with a woven material  14  which is cut into a panel or panels as necessary for a particular design. Each edge  74  of the fabric seating material which is to be retained within the chair frame is folded over and stitched  76  to form an elongated loop  77  along the perimeter of the seat panel. Other methods can be used to form loops on the edge of the fabric such as heat sealing, sonic welding, etc.  
         [0020]    As shown in FIG. 2, groove or slot  78  extends into hollow channel  64 . It is to be understood that depending on the specific design of the chair, groove  78  could extend into any one of the hollow channels in the frame member. Preferably the frame structure is assembled such that the groove runs along the inside surface or underside of the frame member to provide an aesthetically appealing appearance. However, slot  78  can be formed in any surface of the frame.  
         [0021]    The seat panel is attached to the frame by placing a rod  80  into the loop  77  formed in the fabric material  14 . The rod  80  can be flexible or rigid depending upon the designed configuration of the specific chair but has a diameter that is less than the width of groove  78 . The edge of the fabric material  14  having the loop and the rod is then inserted into the channel  78  along with an elongated molded strip  82 . Elongated molded strip  82  can be flexible or rigid again depending upon the design configuration of the specific chair, but includes a wedge portion  84  and a top portion  86 . The wedge portion  84  includes an angled surface  85  and a flat surface  87 . The elongated molded strip including the wedge is pushed behind the fabric immediately after being inserted into the channel  64  to lock the fabric within the channel. This process is performed in a sequential manner along the perimeter of the frame until all of the fabric is trapped in the frame. The wedge has tendency to snap into the frame, as the lip on the wedge passes the undercut of the frame, as the wedge strip is pushed into the slot. The wedge  84  is locked into place by an interference created by a lip  88  formed in the frame along the edge of the groove  78 . The lip  88  forms an undercut molded into the frame. Top portion  86  of the molded strip is flush with the top surface  70  of the frame member upon insertion.  
         [0022]    In the assembled condition, the fabric and rod is trapped in the frame cavity by the wedge preventing the fabric from pulling out of frame. The slot opening formed by the wedge and the frame is smaller than the rod and therefore the fabric cannot come out unless the wedge is removed. The wedge has a tendency to snap and lock into the frame as the wedge strip is pushed into the slot. The additional space in channel  64  provides space for the fabric and rod to move aside as the wedge is pushed into the slot as it registers into the frame.  
         [0023]    The retention method has self-locking feature in that the greater the tension on the fabric, the greater the force holding the wedge in the frame. The lateral force created by the rod attempting to come out of the slot pushes against the wedge in a manner that increases the interference between the flat surface  87  of the wedge portion  84  and the lip  88  in the frame. The angled surface  85  also is forced against an angled surface  89  of support member  68 . To remove the fabric from the frame, the wedge can be pulled out of the slot relaxing the tension on the fabric or with simple tools that push the rod into cavity  64  allowing the fabric to be easily removed from the frame.  
         [0024]    The present invention does not require a secondary means to put tension on the fabric. The process of assembly allows and facilitates the creation of tension in the material as it is being assembled into the frame. Up to four sides can be attached along the surface of the frame. The wedge shape has a tendency to roll the fabric into the frame while in tension. This method simplifies the construction of the frame with a result in lower manufacturing costs compared to prior methods. Without the need for a secondary tensioning mechanism, the retention method of the present invention allows for a rigid frame to be build where the fabric can be captured around the full perimeter. As a result, the fabric can take on contours that are not possible using prior fabric attachment methods. The present method allows for the fabric to be installed on the frame along the surface along any point along the perimeter instead of just at the end of the extrusion as with prior methods.  
         [0025]    The present invention has been described with respect to a preferred embodiment thereof, however other modifications can be made in the invention without departing from the scope of the invention. For example, other alternatives to using a rod on the perimeter of the fabric can be utilized such as sewing any type of round material on the perimeter of the fabric pattern, similar to a cushion welting. The method can also be adapted to a variety of applications that require retaining a flexible material in a frame structure. It need not be limited to seating applications, for example, stretching a material around a frame to serve as a vertical panel or screen or for decorative purposes. These and other aspects of the invention can be further understood by referring to the invention as hereinafter claimed. Although the invention has been illustrated with respect to a patio chair, it is equally applicable to other furniture items such as for example, chaise lounge chairs, tables, ottomans, etc.