Patent ID: 7562728
Filing Date: 2009-07-21
Classification: A61G,Y10S

Abstract:
1. An improvement to a powered wheelchair that includes at least three wheels and wherein two of said three wheels are driven wheels, and wherein a third of said at least three wheels is free spinning and wherein a bottom of said at least three wheels define a first plane, and wherein said bottom of said at least three wheels of said powered wheelchair are disposed on said first plane when said wheelchair is disposed on a generally planar and level surface, the improvement comprising: including two additional driven wheels with said wheelchair in addition to said two driven wheels, and wherein said two additional driven wheels are disposed above said first plane, and wherein said two driven wheels each supply a motive force to urge said wheelchair on said level surface when said wheelchair is disposed on said first plane; wherein said wheelchair is adapted to pivot about an axis passing through a center of said two driven wheels from said first plane to a second plane when said wheelchair is disposed on a generally planar and inclined surface that includes a sufficient degree of incline thereto, and wherein a bottom of said two driven wheels and a bottom of said two additional driven wheels define said second plane, and wherein said bottom of said two driven wheels and said bottom of said two additional driven wheels are disposed on said inclined surface when said wheelchair is disposed on said second plane, wherein when said wheelchair is disposed on said second plane said two driven wheels each supply a motive force to urge said wheelchair on said inclined surface, and wherein when said wheelchair is disposed on said second plane said two additional driven wheels each supply a motive force to urge said wheelchair on said inclined surface, and wherein when said wheelchair is disposed on said second plane said two driven wheels and said two additional driven wheels provide four-wheel drive capability for urging said wheelchair on said inclined surface when said wheelchair is disposed on said second plane; wherein said two driven wheels include a left driven wheel and a right driven wheel, and wherein said two additional driven wheels include a left additional driven wheel and a right additional driven wheel, and wherein drive means is provided to mechanically link said left additional driven wheel to said left driven wheel and to mechanically link said right additional driven wheel to said right driven wheel sufficient so that said left additional driven wheel always rotates in a direction that is equal to that of said left driven wheel whenever said left driven wheel is rotating and wherein said right additional driven wheel always rotates in a direction that is equal to that of said right driven wheel whenever said right driven wheel is rotating; wherein a first motive source that is used to rotate said left driven wheel independently with respect to said right driven wheel is also used to rotate said left additional driven wheel independently with respect to said right additional driven wheel, and wherein a second motive source that is used to rotate said right driven wheel independently with respect to said left driven wheel is also used to rotate said right additional driven wheel independently with respect to said left additional driven wheel; wherein said first of said two driven wheels and said second of said two driven wheels provide differential steering of said wheelchair when said wheelchair is disposed on said first plane, and wherein said first of said two additional driven wheels and said second of said two additional driven wheels do not provide differential steering of said wheelchair when said wheelchair is disposed on said first plane; wherein said first of said two driven wheels and said second of said two driven wheels provide differential steering of said wheelchair when said wheelchair is disposed on said second plane, and wherein said first of said two additional driven wheels and said second of said two additional driven wheels provide differential steering of said wheelchair when said wheelchair is disposed on said second plane; and wherein when said wheelchair is disposed on said inclined surface and on said second plane said third of said at least three wheels is not disposed on said inclined surface.