Patent Publication Number: US-7914081-B1

Title: Contoured sling wheelchair seat

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 11/760,633, filed on Jun. 8, 2007, which claims the benefit of Provisional Application No. 60/812,584, filed Jun. 8, 2006, the disclosure of which is hereby expressly incorporated by reference. 
    
    
     BACKGROUND 
     A standard wheelchair seat consists of a flexible sling material. The material has adequate strength to support the weight of the user. However, the basic sling shape creates dangerous high pressure areas to the user&#39;s skin. The prolonged high pressure can cause pressure sores leading to potentially fatal Pressure Ulcers. The typical method to improve the pressure distribution and support of a person in a wheelchair is to add an additional seat cushion system on top of the wheelchair seat sling. There are many different types of cushioning and support systems. They may use air bladders, fluid filled bags, different density foams, contoured foams or a combination of several technologies. Examples of these methods are shown in U.S. Pat. Nos. 5,687,436; 5,282,286; 4,726,624; and 5,839,140. 
     Another method is shown in U.S. Pat. Nos. 6,755,477 and 6,264,279 in which multiple layers of flexible non-uniform material such as Lycra or Polartec are specified. The non-uniform materials are used in combination with flexible and/or stiffened materials between the layers to give the seat contours to improve the pressure distribution. Another method is shown in U.S. Pat. Nos. 5,857,749 and 5,984,418 in which the flexible material is replaced with a rigid base on which a cushion is attached. All the known methods come at the price of added cost, weight and complexity to the seating system. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     A wheelchair seat including three layers of substantially flexible material of uniform stiffness material having sufficient strength to support an occupant. The three layers of substantially flexible material forming a seat region having a top layer, a middle layer and a bottom layer. The seat region adapted to be coupled to frame side rails of a wheelchair. The wheelchair seat further including a plurality of flexible pads disposed between the upper and middle layers. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of the contoured sling seat attached to a wheelchair frame with the wheels and backrest fabric of the wheelchair removed for clarity; 
         FIG. 2  is a cross-section of the edge of the seat fabric wrapping around the seat attachment strip; 
         FIG. 3  is a cross-section of the central abductor contour; and 
         FIG. 4  is a cross-section of a pressure relief pocket. 
     
    
    
     DETAILED DESCRIPTION 
     A contoured sling wheelchair seat constructed in accordance with one embodiment of the present disclosure may be best understood by referring to  FIGS. 1-4 . The contoured sling wheelchair seat includes a contoured seat fabric  1  which spans across the width of the wheelchair frame  2  and is attached with the use of two seat attachment strips  15 . The seat attachment strips  15  are suitably secured to the wheelchair frame  2  side rails with multiple screws  5  which pass through the seat fabric  1  and seat attachment strips  15  and are then screwed into top side of the wheelchair frame  2  side rails. 
     As may be best seen by referring to  FIGS. 1 and 2 , the contoured seat fabric  1  is constructed of multiple layers of substantially flexible material with adequate strength to support the entire weight of the occupant. The contoured seat fabric  1  includes an upper layer  10 , a lower layer  11  and a middle layer  12 . The upper, middle and lower layers defining a seat region. At the two outer edges of the contoured seat fabric  1 , the outer layer  10  and lower layer  11  wrap around the upper surface of the seat attachment strip  15  and continue around to the underside of the seat attachment strip  15 , the two layers continue past the attachment strip  15  an adequate distance to have two rows of stitching  14  pass through them. The middle layer  12  spans across the width of the seat up to the seat attachment strips  15  at either side. The two rows of stitching  14  bind together the upper and lower layers of fabric  10 ,  11  to envelop the seat attachment strip  15  along with securing the middle layer  12 . 
     As may be best seen by referring to  FIGS. 1 and 3 , at the forward edge of the contoured seat fabric  1  at its centerline there is a central abductor contour  4 . The central abductor contour  4  is accomplished by inserting a section of foam  13  between the upper layer  10  and the middle layer  12 . The foam is scalloped at its edges to smoothly transition back to the seat surface. The foam  13  is held in place by a row of stitching  16  which follows around the outer circumference of the foam  13  and binds together the three layers of fabric  10 ,  11 ,  12 . 
     As may be best seen by referring to  FIGS. 1 and 4 , in order to reduce pressure under the Ischial Tuberosities there are two pressure relief pockets  3  of reduced stiffness in the seat fabric dimensioned to have areas corresponding to the user&#39;s Ischial Tuberosities. The reduced stiffness is accomplished by removing the middle layer of fabric  12  in the area of the pockets  3 . The three seating layers  10 ,  11 ,  12  are secured to each other around the perimeter of the pockets  3  with a row of stitching  17 . 
     A seating system for wheelchairs and other applications. The seating system incorporates contours in the substantially flexible seat sling to improve the pressure distribution of the seated user. The seat sling having a width dimension between opposite sides sufficient to span across spaced wheelchair seat frame members for support on top of said seat frame members. The seat sling material has adequate material strength to provide a seat base for the sole support of a user while seated thereon when the seat material is mounted to the seat frame members. 
     The contours in the seat sling are accomplished through a variety of well-known methods. Sewn-in contours can change the shape of the seat to match the shape of the user. The use of strategically placed and shaped filler material within the seat sling can change the shape of the upper surface of the seat. The use of lower stiffness material within the seat sling can lower the pressure in a region of the seat. Transitioning from higher density filler material to lower density filler material can change the pressure in a given area of the seat. 
     There are several advantages to building the contours into the structural seat sling. Without the need for a secondary seat cushion the cost and the weight of the seating system is reduced. The additional effort to remove the seat cushion every time the wheelchair is folded or transported is eliminated. The potential for breathable mesh materials to be used can improve air circulation and allow moisture to move away from the skin. 
     While illustrative embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.