Curb-climbing power wheelchair

Abstract

A mid-wheel drive power wheelchair for use by handicapped and disabled persons is provided having a frame, a seat supported by the frame, a pair of drive wheels supported on the frame under the seat, drive means for causing rotation of the drive wheels, power means for supplying power to the drive means, a rearward idler wheel, a forward anti-tip device and a resilient suspension supporting the forward anti-tip device, the suspension being attached to the drive means rearward of the front portion of the frame.

1 - 119 . (canceled) 
   
   
       120 . A power wheelchair comprising:
 a. a frame;   b. a seat supported by said frame;   c. a pair of drive wheels positioned below a central portion of said seat on opposite sides of said frame and supported thereon, said drive wheels rotatable about transverse axes;   d. drive means operatively connected to said frame for causing rotation of said drive wheels;   e. power means for supplying power to said drive means to move the wheelchair;   f. control means for controlling the rotation of said drive wheels by said drive means;   g. at least one idler wheel operatively connected to said frame and positioned behind said drive wheels and rearward of the back of said seat, said idler wheel mounted for rotation about a horizontal axis and supported for rotational movement about a vertical axis;   h. at least one anti-tip device operatively connected to said frame and positioned forward of said drive wheels and said frame, said anti-tip device being in engagement with the ground when said drive wheels and said rear idler wheel are in their normal ground-engaging position on level ground; and   i. a resilient suspension supporting said forward anti-tip device, said suspension comprising a first assembly and a second assembly, said first assembly being operatively attached to said drive means at a first location proximate one portion thereof, and said second assembly being operatively attached to said drive means at a second location proximate another portion thereof, said first assembly being further operatively attached to said frame at a third location, and said second assembly being operatively attached to said frame at a fourth location.   
   
   
       121 . The power wheelchair of  claim 120 , wherein each of said first, second, third and fourth location operative attachment points is no further forward than the front portion of said frame. 
   
   
       122 . The power wheelchair of  claim 120 , wherein said anti-tip device is an idler wheel,
 said idler wheel mounted for rotation about a horizontal axis and supported for rotational movement about a vertical axis.   
   
   
       123 . The power wheelchair of  claim 122 , wherein said idler wheel is a caster wheel. 
   
   
       124 . The power wheelchair of  claim 120 , wherein each of said resilient suspension third location and fourth location operative attachment points are coincident with the front portion of said frame. 
   
   
       125 . The power wheelchair of  claim 120 , wherein each of said resilient suspension third location operative attachment point and fourth location operative attachment point is a pivotal attachment. 
   
   
       126 . The power wheelchair of  claim 120 , wherein said resilient suspension first assembly includes a first spring assembly and connecting means, said first spring assembly being operatively attached at one end thereof to said drive means at said first location, and operatively attached at another end thereof to said connecting means at a fifth location, said connecting means being operatively attached to said frame at said third location, and wherein said resilient suspension second assembly includes a second spring assembly, said second spring assembly being operatively attached at one end thereof to said drive means at said second location, and operatively attached at another end thereof to said frame at said fourth location. 
   
   
       127 . The power wheelchair of  claim 126 , wherein said connecting means operative attachment third location is coincident with the front portion of said frame and said second spring assembly operative attachment fourth location is coincident with the front portion of said frame. 
   
   
       128 . The power wheelchair of  claim 126 , wherein said first spring assembly includes a first spring and a first shaft, said first spring surrounding said first shaft, and said first shaft being operatively attached at one end thereof to said drive means at said first location, and operatively attached at another end thereof to said connecting means at said fifth location. 
   
   
       129 . The power wheelchair of  claim 126 , wherein said second spring assembly includes a second spring and a second shaft, said second spring surrounding said second shaft, and said second shaft being operatively attached at one end thereof to said drive means at said second location, and operatively attached at another end thereof to said frame at said fourth location. 
   
   
       130 . The power wheelchair of  claim 126 , wherein said connecting means is operatively attached to said anti-tip device at a sixth location. 
   
   
       131 . The power wheelchair of  claim 120 , wherein the power wheelchair includes a pair of anti-tip devices and a pair of resilient suspensions, each one of said resilient suspensions being operatively connected to one of said anti-tip devices. 
   
   
       132 . The power wheelchair of  claim 126 , wherein the power wheelchair includes a pair of anti-tip devices and a pair of resilient suspensions, each one of said resilient suspensions being operatively connected to one of said anti-tip devices. 
   
   
       133 . The power wheelchair of  claim 120 , wherein said seat has a cushion portion for supporting an operator's thighs and buttocks and a back portion for supporting an operator's back when the operator is in a seated upright position. 
   
   
       134 . The power wheelchair of  claim 120 , which further includes a seat support member attached to said frame for supporting said seat above said frame. 
   
   
       135 . The power wheelchair of  claim 120 , wherein said drive wheels are positioned below a central portion of said seat. 
   
   
       136 . The power wheelchair of  claim 120 , wherein said drive means includes at least one motor for powered movement of the wheelchair. 
   
   
       137 . The power wheelchair of  claim 120 , wherein said power means includes a battery. 
   
   
       138 . The power wheelchair of  claim 120 , wherein said fifth location operative attachment point is rearward of said third location operative attachment point and rearward of the front portion of said frame, and wherein said fourth location operative attachment point is at least coincident with said third location operative attachment point and is no further forward than the front portion of said frame 
   
   
       139 . The power wheelchair of  claim 126 , wherein said fifth location operative attachment point is rearward of said third location operative attachment point and rearward of the front portion of said frame, and wherein said fourth location operative attachment point is at least coincident with said third location operative attachment point and is no further forward than the front portion of said frame 
   
   
       140 . The power wheelchair of  claim 126 , wherein said anti-tip device is forward of the front portion of said frame and each of said first spring assembly and said second spring assembly is rearward of said anti-tip device and is no further forward than the front portion of said frame. 
   
   
       141 . The power wheelchair of  claim 126 , wherein said anti-tip device is forward of the front portion of said frame and each of said first spring assembly and said second spring assembly is rearward of the front portion of said frame. 
   
   
       142 . The power wheelchair of  claim 126 , wherein each of said first spring assembly and said second spring assembly comprises a shaft, a spring surrounding said shaft and in operative contact with said drive means, and a nut assembly mounted on said shaft and in operative contact with said drive means and said spring for providing selectable compression of said spring in order to provide adjustment of the spring force applied to said anti-tip device to resist arcuate upward movement thereof upon forward tipping of the power wheelchair or upon said anti-tip device encountering an obstacle. 
   
   
       143 . The power wheelchair of  claim 126 , wherein said connecting means includes more than one attachment point for selective pivotal attachment of said first spring assembly to said connecting means at said fifth location. 
   
   
       144 . The power wheelchair of  claim 126 , wherein said resilient suspension includes means for adjusting the length of each of said first spring assembly and said second spring assembly. 
   
   
       145 . The power wheelchair of  claim 126 , wherein the pre-load force of each of said first spring assembly and said second spring assembly is adjustable by compressing or decompressing each of said first spring assembly and said second spring assembly. 
   
   
       146 . The power wheelchair of  claim 126 , wherein said anti-tip device is an idler wheel, said idler wheel mounted for rotation about a horizontal axis and supported for rotational movement about a vertical axis. 
   
   
       147 . The power wheelchair of  claim 126 , wherein said idler wheel is a caster wheel. 
   
   
       148 . The power wheelchair of  claim 126 , wherein said first connecting means operative attachment fifth location is a pivotal attachment, and wherein said second spring assembly operative attachment fourth location is a pivotal attachment.