Abstract:
The invention is a lumbar support structure adapted to attach to a frame of a seat. An upper support bar and a lower support bar attach to the frame of the seat. A plurality of vertical springwires connect to the support bars. Spacers are used to maintain a desired distance between each of the springwires. A lumbar portion of the springwires extends away from a plane containing the support bars. By utilizing different diameter springwires and different shaped lumbar portions a saddle support distribution is created. The saddle support distribution allows the structure to customize the response to an occupant sitting in the seat.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   None. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention concerns a weight support device for seats. More specifically, the invention is drawn to a wire array for a seat to support the back of a seated occupant. The support is generated by conforming the shape of the device to the particular seat into which it is installed and also by conforming the shape of the device to the lower back region (i.e. lumbar region) of the occupant, either statically or dynamically. 
   2. Related Art 
   It is known to provide generally static wire arrays for seat support that can also be manipulated to adjust for lumbar support in a seat. See U.S. Pat. Nos. 5,474,358; 5,697,672; 5,988,745 and 6,152,531, European Patent No. 0128407A1 and UK patent application GB 2342287A (all commonly owned and hereby incorporated by reference) for examples of the prior art. All of these disclosures utilize a horizontal array of wires to provide support. Vertical elements only space the wires to distribute applied loads. Multiple attaching devices must be used to attach the devices to a frame in a seat to prevent unwanted twisting of the support. 
   All of these devices provide static support. They are all flexible enough to have their shape and tension altered dynamically by any of a variety of user control mechanism. These horizontal arrays address a constant industry need for controlling component cost. However, installation in various seat frames requires multiple mounting components especially when a dynamic capability is added. Moreover, the load bearing and tension control characteristics of horizontal wires, bent or straight, have low adaptability to various seat frames and to individual seat occupants. 
   Some of these horizontal devices utilize different shapes in the wires to increase the effective area providing support. None of the patents disclose the use of different diameter wires and different shapes to customize the response to an applied load. 
   U.S. Pat. No. 4,283,046 discloses a static system utilizing an array of vertically arranged wires to provide uniform support. This device also discloses one mechanism to change the profile of the support. This device does not disclose the use of different diameter wires and different bending patterns to customize the response to an applied load. 
   There is a need in the industry for a vertical wire array that controls component cost and provides greater adaptability of installed load bearing and tension response characteristics. 
   SUMMARY OF THE INVENTION 
   The invention is a lumbar support structure adapted to attach to a frame of a seat. Horizontal upper and lower support bars attach to the frame of the seat. A plurality of vertical springwires connect to the support bars. Horizontal spacers are used to maintain a desired distance between each of the springwires. A lumbar portion of the springwires is curved toward a seat occupant, extending away from a plane defined by the support bars. By utilizing different diameter springwires and different shaped lumbar portions of the springwires, a saddle type support distribution is created. The novel combination of vertical alignment with variable wire diameter and bending patterns allows the structure to customize the wire array to the seat into which it is installed and its response to an occupant sitting in the seat. 
   Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the embodiments of the present invention and together with the description, serve to explain the principles of the invention. In the drawings: 
       FIG. 1  illustrates a front plan view of the Lumbar Support Structure; 
       FIG. 2  illustrates side views of various springwire bending patterns; and 
       FIG. 3  illustrates the saddle support distribution. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the accompanying drawings in which like reference numbers indicate like elements,  FIG. 1  illustrates the support structure  1  viewed from the front. The support structure  1  provides support to the occupant of a seat. In the preferred embodiment the invention is incorporated into an automobile seat but could be used in any type of seat. The support structure  1  attaches to a frame  5  (shown in shadow) of the seat (not shown). 
   The support structure  1  comprises an upper support bar  10  and a lower support bar  14 . An upper attachment device  12  attaches the upper support bar  10  to the frame  5 . In one preferred embodiment, upper attachment device  12  is a pair of clips which connect to holes on the frame  5 . A lower attachment device  16  attaches the lower support bar  14  to the frame. In one preferred embodiment, the lower attachment device  16  is a pair of clips. Of course any type of attachment device could be utilized. For example the upper support bar could fit into the crook of a hook attached to the frame. Alternatively, the attaching clip may be an inexpensive bend fabricated into the end of the support bars  10  and  14 . Consequently, mounting component costs are reduced. 
   A plurality of vertical spring wires  30  are attached to the horizontal bars  10  and  14 . The horizontal bars  10  and  14  are more rigid than the vertical spring wires. This further reduces any need for expensive mounting components that might otherwise be needed to prevent twisting. Also, rigid horizontal support bars  10  and  14  provide a desirable resistance to load bearing flexion of the vertical springwires  30 . In one preferred embodiment, the upper support bar  10  and lower support bar  14  are rods of spring steel and have a diameter of 4 to 5 mm. 
   Upper support bar  10  and lower support bar  14  define a support plane. The plurality of springwires  30  attach at an upper portion  32  to the upper support bar  10  and at a lower portion  34  to the lower support bar  14 . A lumbar portion  36  is located between upper portion  32  and lower portion  36 . Preferably, the lumber portion  36  is curved towards a seat occupant for support, although flat wire assars are within the scope of the present invention. 
   At least one spacer  40  has a plurality of holes that allow the plurality of springwires  30  to pass through the holes. The spacer  40  maintains a desired distance between the springwires  30 . The spacer  40  is made of plastic in one preferred embodiment, but could be made of any suitable material. In one preferred embodiment, the spacer  40  is operatively connected to the springwires  30  using the holes mentioned above but the springwires  30  could be operatively coupled to the spacer  40  in any suitable manner. For example, the springwires  30  could wrap around the spacer. 
   The lumbar portion  36  of springwires  30  extends away from the support plane to provide support to the occupant of the seat. Alternatively, the wire array comprising the support structure  1  may be flat. Different shapes or bending patterns are incorporated into lumbar portion  36  to provide the desired support. The lumbar portion  36  of each wire can be arc shaped, round, trapezoidal, see  FIG. 2 , or any other suitable shape. Each varying shape will have varying load bearing characteristics. Moreover, various combinations of the shape of adjacent wires allow for an adaptability of the weight bearing and tension response characteristics of the wire array as a whole. The variability of the disclosed system allows for a much greater degree of adaptability of installation of the wire array in different seats with different frames and different dynamic adjustment mechanisms than was provided in the prior art, without increasing cost. 
   Upper support bar  10  and lower support bar  14  define a support plane. The plurality of springwires  30  attach at an upper portion  32  to the upper support bar  10  and at a lower portion  34  to the lower support bar  14 . A lumbar portion  36  is located between upper portion  32  and lower portion  34 . Preferably, the lumber portion  36  is curved towards a seat occupant for support, although flat wire array are within the scope of the present invention. 
   Individual springwires  30  may also made of different diameter wires. The stiffness of the springwires  30  is a function of the material and the thickness or gauge of the wire. The thicker springwires are stiffer than thinner springwires. Of course, different materials may also be used, such as metal straps or plastic members. Accordingly, even greater adaptability of the system is available. 
   The configuration of the support structure  1  can be adjusted according to design requirements. It has been determined that the most comfortable arrangements of lumbar support incorporate a saddle support distribution  50  into the design, see  FIG. 3 . A preferred saddle support distribution  50  provides a region of reduced support adjacent to the passenger&#39;s spine, bordered laterally by regions of increased support. The support device  1  has a centerline corresponding to the spine of an occupant  52 . Preferably, there are no springwires in the centerline. A first pair of springwires  30 A is disposed adjacent the centerline. The first pair of springwires has a first stiffness. A second pair of springwires  30 B is disposed outside of the first pair of springwires and has a second, preferably increased stiffness. Subsequent pairs of springwires  30 C are disposed outside of the preceding pair of springwires and have additional stiffness. The saddle support distribution is created by having the springwires increase in stiffness from the centerline outward up to a maximum stiffness. The farthest lateral springwires may decrease in stiffness. The use of differing shapes  54 A,  54 B and  54 C in the lumbar region of progressive spring wire pairs will allow further customization of the support. These shapes may be different bending patterns, or may be different sizes of the same pattern. 
   Furthermore, greater adaptability of the system may be achieved by making one or more of the springwires longer than other springwires, as shown for example in  FIG. 3  where any one of springwires  30 A,  30 B, or  30 C is longer (due in this case to bends in these wires) than at least one other springwire, such as springwire  30 . Use of longer springwires closer to the centerline is another way to generate a saddle support distribution as described above, for example in  FIG. 3  springwires  30 A,  30 B, and  30 C are more centrally disposed relative to springwire  30 . 
   In use the device will be incorporated into a seat. The upper support bar and lower support bar attach to the frame of the seat. The rest of the padding and covering will then be added to the seat. Provided an occupant sits in the center of the seat, the empty portion along the centerline will line up with the occupant&#39;s spine yielding slightly as the occupant presses back into the seat. The springwires will then provide resistance. The stiffest resistance will come from the springwires with the highest stiffness. The saddle support distribution cradles the spine of the occupant. 
   In fabrication and assembly, the wire gauges, bending patterns and saddle shape may all be adjusted to accommodate a variable range of seat designs, frames and dynamic support adjustment mechanisms that a seat manufacturer may use. Accordingly, this single wire array product may be quickly and inexpensively customized for use in a broad range of seats without redesign or retooling. 
   The shaped, vertically aligned wire array is adaptable to any manner of dynamic tensioning system. The shape of the spring wires in their lumbar portion  36  can be changed to accommodate horizontal strap type systems, bowing systems using vertical tension or compression, or push paddle type support systems. 
   The vertical springwire configuration provides advantages over the horizontal springwire configuration. Prior art horizontal springwires flexed outwardly when loaded. In contrast, the vertical springwire configuration is relatively fixed at an upper portion and a lower portion to the support bars. When loaded the wires do not have the room to flex and thus the springwires are placed in compression, increasing their resistance to progressive loading. These load characteristics are then customized by incorporating variable bending patterns. 
   In view of the foregoing, it will be seen that the several advantages of the invention are achieved and attained. 
   The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. 
   As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. For example, the spacer is disclosed as having a hole that passes over a springwire, but the spacer could also be glued to the springwire. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.