Abstract:
An improved seat suspension assembly with axially adjustable roller and guide assemblies. The suspension uses an adjustment member the actuation of which causes the axial movement of either the roller or guide so as to adjust the spatial relationship between the roller and guide.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an improved seat suspension system using a unique roller and channel or guide assembly as part of the suspension system. Typically, seat suspensions use roller assemblies mounted to shafts and adapted to cycle back and forth in metal channels or guides. The roller assemblies are often associated with a scissor arm which, in turn, operates in conjunction with a spring and shock absorber to increase the comfort of the occupant in the seat. 
     However, due to the difficulty and/or costliness of maintaining manufacturing tolerances or through use and associated wear, the optimal positioning or tolerance between the roller assemblies and their respective guides is often difficult to achieve and maintain. In operation of the seat suspension, a precise tolerance between the two components is desired since unwanted play produces axially movement that accelerates wear and causes potential discomfort to the occupant. 
     SUMMARY OF THE INVENTION 
     The present invention provides an axially adjustable roller and guide assembly which allows the optimal position between the two components to be achieved and maintained, and thus, eliminates or minimizes any undesired axial movement. The present invention incorporates on a seat suspension a positionable adjustment member that reduces unwanted play by axially adjusting the spatial distance between the roller and its respective guide by urging one of the two components axially with respect to the other component. The adjustment member may be located in a number of different positions and it is used to achieve a precise tolerance between the two components. 
     It is, therefore, an object of the present invention to provide a seat suspension assembly in which the axial alignment of a roller with respect to a guide may be adjusted after manufacture in order to place the roller in an optimal position with respect to the guide prior to or during use in order to reduce or eliminate unwanted axial movement or play in the seat. 
     Another object of the present invention is to provide a seat suspension assembly in which the axial alignment of a roller with respect to a guide may be adjusted after prolonged use of the device in order to maintain and/or reposition the roller in an optimal position with respect to the guide in order to reduce or eliminate unwanted axial movement. 
     It is another object of the present invention to provide an adjustment member that urges a roller axially with respect to a guide in order to maintain an optimal spatial relationship between the roller and guide. 
     A further object of the present invention is to provide an adjustment member that urges a guide axially with respect to a roller in order to maintain an optimal spatial relationship between the roller and guide. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
     FIG. 1 is a perspective view of a typical seat suspension using one embodiment of the present invention. 
     FIG. 2 is an enlarged partial front view of the embodiment shown in FIG. 1 with portions removed to reveal aspects of the present invention. 
     FIG. 3 is a perspective view of the embodiment shown in FIG. 1, again, with portions removed to reveal aspects of the present invention. 
     FIG. 4 is partial cross-sectional view of the embodiment shown in FIG. 3 taken along line  4 — 4 . 
     FIG. 5 is a fragmentary cross-sectional view of a roller assembly with a shaft disposed therein. 
     FIG. 6 is a partial cross-sectional view illustrating a second embodiment of the present invention. 
     FIG. 7 shows another cross-sectional view illustrating a third embodiment of the present invention. 
     FIG. 8 shows another partial cross-sectional view illustrating a fourth embodiment of the present invention. 
     FIG. 9 is a perspective view illustrating a fifth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Set forth below is a description of what are currently believed to be the preferred embodiments or best examples of the invention claimed. Future and present alternatives and modifications to the preferred embodiments are contemplated. Any insubstantial changes or modifications in function, purpose, structure or result are intended to be covered by the claims of this patent. 
     As shown in FIG. 1, the present invention may be used in seat suspensions  10  having parallel pairs of scissor arms  12  and  14  which are in turn connected to a shock absorber  24 . The scissor arms are also attached to opposingly located rollers  16  and  18  which travel in channels or guides  20  and  22 . Typical examples of some of the different types of mechanical seat suspensions in which the present invention may be used are shown and described in U.S. Pat. Nos. 4,856,763 and 5,125,631, which are incorporated herein by reference. Of course, the present invention is not limited to use in scissor-type seat suspensions but also may be used in other types of seat suspensions in which rollers and guides are used as part of the suspension system. One type of roller that may be used with the present invention is of the design described and shown in U.S. Pat. No. 5,468,070, which is incorporated herein by reference. 
     Roller assembly  18  (here illustrated as a double roller) is affixed to shaft  19  which is part of the seat suspension. Roller assembly  18  has a side wall  32  and is positioned on guide  22  which has opposing guide surfaces  34  and  36 . Guide  22  also has a side wall  38  which engages or is positioned in close proximity to side wall  32  of roller  18 . As is also shown in FIG. 3, the same design and construction may also be used for all other rollers and guides used in the suspension such as rollers  16  and  40  and guides  20  and  42 . 
     To maintain a desired clearance between the side walls of the roller assembly and guide or a desired predetermined spatial relationship between the roller assembly and guide, the present invention employs an adjustment member  60 . In one preferred embodiment, adjustment member  60  may be located on an angled portion  54  of arm  56  and is disposed between arm  56  and roller  18 . Adjustment member  60  has an angled surface  62  which slidingly engages angled arm portion  54  of arm  56 . In addition, the angle of surface  62  is the same as the angle of arm portion  54  so that surface  64  of adjustment member  60  remains parallel to the surface  21  of roller  18  or perpendicular to shaft  19  during the sliding engagement between member  60  and arm  56 . 
     Using an angled surface on adjustment member  60  provides a variation in distance between surfaces  62  and  64  which allows the position of roller  18  with respect to guide wall  38  to be adjusted by slidingly positioning adjustment member  60  on arm  56 . Providing an adjustment member with a graduation in transverse dimension along its length permits the roller to be positioned in a plurality of adjustment positions. 
     One preferred shape that may be used for an adjustment member is a wedge-shaped structure such as is shown. This configuration provides a useful graduation in transverse dimension that permits fine positioning adjustments to be made. Of course, other shapes using variations in transverse dimension may be used as well and such shapes would be known to those of skill in the art and covered by the claims of the present invention. 
     In addition, to permit adjustment member  60  to move about shaft  19 , it may include an elongated aperture (not shown) through which shaft  19  extends. Alternatively, member  60  may include two leg portions (not shown) which extend on opposing sides of shaft  19 . 
     As shown in FIGS. 3 and 4, fastener  70  may be used to fix the position of adjustment member  60  on arm  56 . Fastener  70  extends through elongated bore  80  and into coacting threads in arm  56  (not shown). In addition, the fastener head may be disposed within recess  82  to minimize interference with the operation of the suspension. 
     As shown in FIG. 5, shaft  19  is disposed inside roller  18  and terminates at a point that is spaced from the vertical wall  32  to form space or gap  90 . Space  90  permits adjustment of the roller without interference from shaft  19 . 
     In an alternate embodiment, adjustment member  119  may be an axially positionable shaft that employs coacting threads to adjust the position of the roller with respect to the guide. As shown in FIG. 6, roller  18  is axially adjusted by coacting threaded members  110  and  120  the rotation of which changes the axial position of the shaft and attached stop  110 , and in turn, urges roller  18  towards or away from side wall  38 . 
     In yet another alternate embodiment, the adjustment member may be comprised of an articulating lever  130  having opposing ends  131  and  133 . End  131  engages a fastener  132  and end  133  causes the axial movement of roller  18 . As lever  130  pivots about fulcrum or pivot point  134  through the use of fastener  132 , end  133  urges roller  18  to either move axially toward or away from guide wall  38 —thus adjusting the roller&#39;s position with respect to the guide. 
     As shown in FIGS. 8 and 9, the adjustment member may also act upon the guide as well. In yet another embodiment and as shown in FIG. 8, a positionable adjustment member  160 , similar in design and function to adjustment member  60 , is used to axially position the guide with respect to roller  18 . Alternatively, a fastener  200  may also be used to axially adjust the position of the guide either toward or away from the roller as shown in FIG.  9 . 
     The present invention may be used at the time the suspension is manufactured or assembled or after a period of prolonged use to account for any loss in the tolerance or distance between the side wall of the roller and the side wall of the guide. Since opposingly located rollers are often used in seat suspensions, any excess distance or play between the side walls of the roller and guide will result in needless axial movement of the seat. To eliminate this play, the adjustment member of the present invention may be used in combination with each roller and guide assembly on a suspension. More specifically, in the embodiments shown in FIGS. 1-4 and  8 , increasing or decreasing the amount of transverse distance used by the adjustment member acts to create axial movement which adjusts the positions of the roller with respect to the guide. In the embodiments shown in FIGS. 6,  7  and  9 , rotating the threaded fastener or adjustment member also creates axial movement which adjusts the position of the roller with respect to the guide. 
     It should be understood that various changes and modifications to the preferred embodiment described would be apparent to those skilled in the art. Changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is, therefore, intended that such changes and modifications be covered by the following claims.