초록 ▼

A wheelchair and drive mechanism powered by reciprocating operation of a drive lever. The drive mechanism provides a continuously variable gear ratio allowing wheelchair operation at varying speeds and on differing inclines; and is readily fitted to a standard wheelchair by a drive-associated bayone

A wheelchair and drive mechanism powered by reciprocating operation of a drive lever. The drive mechanism provides a continuously variable gear ratio allowing wheelchair operation at varying speeds and on differing inclines; and is readily fitted to a standard wheelchair by a drive-associated bayonet mount. A drive mechanism ratchet wheel includes an upper and lower radial crank secured for rotation thereabout by an axle. Each crank includes a pawl assembly that engages with circumferential ratchet wheel teeth to transfer drive energy supplied to the radial cranks from connecting arms to the ratchet wheel. The connecting arms are coupled to a reciprocating lever arm and operate in concert with the pawls to alternately engage with and transfer energy to the ratchet wheel, or disengage therefrom. While one connecting arm and associated pawl is transferring energy to the ratchet wheel, the other connecting arm is disengaging an associated pawl from the ratchet wheel. Energy is transferred during both a forward and rearward stroke of the lever arm to effect efficient wheelchair and drive operation.

대표청구항 ▼

1. A wheel chair, comprising, a chair frame; at least one lesser diameter wheel mounted to said frame at a front base portion thereof; two larger diameter drive wheels mounted to said frame at a rear base portion thereof; and at least one drive mechanism fastened to one of said drive wheels fo

1. A wheel chair, comprising, a chair frame; at least one lesser diameter wheel mounted to said frame at a front base portion thereof; two larger diameter drive wheels mounted to said frame at a rear base portion thereof; and at least one drive mechanism fastened to one of said drive wheels for direct transfer of drive energy thereto, said drive mechanism including; (a) a lever arm having a first end portion thereof fastened to said frame for reciprocal pivotal movement about a first pivot point at a front base portion thereof, and having a second end portion including a hand grip to allow operator effected reciprocal pivotal movement about said first pivot point; (b) at least one connecting rod, said rod having a first end portion thereof fastened to said lever arm for pivotal movement about a second pivot point at a lever arm midportion, and having a second end portion; (c) at least one pawl fastened to each connecting rod for pivotal movement about a third pivot point at said second connecting rod end portion; (d) at least one radial crank having a first end portion thereof fastened to an associated pawl for pivotal movement about a fourth pivot point, said fourth pivot point being noncoincident with said third pivot point, and having a second end portion thereof fastened for pivotal movement about a central pivot point coaxial with a drive wheel axle; and (e) a ratchet wheel having a center portion fastened for rotational movement about said central pivot point, and having a plurality of circumferential teeth for engagement with said pawl; whereby lever arm operation in one direction engages said pawl with said ratchet wheel teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction. 2. The wheelchair of claim 1, further comprising: at least one brake means associated with one of said drive wheels for selectably stopping wheel movement. 3. The wheelchair of claim 1, said lever arm including: means for adjusting connecting rod spacing at said second pivot point from said first pivot point to selectably vary resulting connecting rod movement, whereby a continuously variable drive mechanism gear ratio is provided. 4. The wheelchair of claim 1, further comprising: bayonet mount means for removably fastening said drive mechanism to one of said drive wheels. 5. The wheelchair of claim 1 and including two connecting rods, two pawls and two radial cranks, whereby lever arm operation in the first direction engages the first pawl with said ratchet wheel teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction engages the second pawl with said ratchet wheel teeth, and disengages said first pawl therefrom, for translation of reciprocal lever arm movement to rotational ratchet wheel movement in said drive direction. 6. In a wheelchair including a chair frame, at least one lesser diameter wheel mounted to said frame at a front base portion thereof, and two larger diameter drive wheels mounted to said frame at a rear base portion thereof, a wheelchair drive mechanism, comprising: a lever arm having a first end portion thereof adapted to be fastened to said frame for reciprocal pivotal movement about a first pivot point at a front base portion thereof, and having a second end portion including a hand grip to allow operator effected reciprocal pivotal movement about said first pivot point; at least one connecting rod, said rod having a first end portion thereof fastened to said lever arm for pivotal movement about a second pivot point at a lever arm midportion, and having a second end portion; at least one pawl fastened to each connecting rod for pivotal movement about a third pivot point at said second connecting rod end portion; at least one radial crank having a first end portion thereof fastened to each pawl for pivotal movement about a fourth pivot point, said fourth pivot point being nonconincident with said third pivot point, and having a second end portion thereof fastened for pivotal movement about a central pivot point coaxial with a drive wheel axle; a ratchet wheel having a center portion fastened to one of said drive wheels for direct transfer of drive energy thereto by rotational movement of said ratchet wheel above said central pivot point, said ratchet wheel having a plurality of circumferential teeth for engagement with said pawl; whereby lever arm operation in one direction engages said pawl with said ratchet wheel teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction. 7. The drive of claim 6, further comprising: at least one brake means associated with one of said drive wheels and operable by manipulation of a hand control fastened to said lever arm, to provide selectable stopping of wheel movement. 8. The wheelchair of claim 5, said lever arm including: means for adjusting connecting rod spacing at said second pivot point from said first pivot point to selectively vary resulting connecting rod movement, whereby a continuously variable drive mechanism gear ratio is provided. 9. The drive of claim 6, further comprising: bayonet mount means adapted for removably fastening said drive mechanism to one of said drive wheels. 10. The wheelchair drive mechanism of claim 6 and including two connecting rods, two pawls, and two radial cranks, whereby lever arm operation in a first direction engages the first pawl with said ratchet teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction, and whereby lever arm operation in the second, opposite direction engages the second pawl with said ratchet wheel teeth, and disengages said first pawl therefrom, for translation of reciprocal lever arm movement to rotational ratchet wheel movement in said drive direction. 11. A drive mechanism adapted to be fastened to a vehicle drive wheel for direct transfer of drive energy thereto, comprising: a lever arm having a first end portion thereof fastened to a vehicle frame for reciprocal pivotal movement about a first point at a front base portion there of, and having a second end portion including a hand grip to allow operator effected reciprocal pivotal movement about said first pivot point; at least one connecting rod, said rod having a first end portion thereof fastened to said lever arm for pivotal movement about a second pivot point at a lever arm midportion, and having a second end portion; at least one pawl fastened to each connecting rod, for pivotal movement about a third pivot point at said connecting rod second end portion; at least one radial crank having a first end portion thereof fastened to said pawl, for pivotal movement about a fourth pivot point, said fourth pivot point being noncoincident with said third pivot point, and having a second end portion thereof fastened for pivotal movement about a central point coaxial with a drive wheel axle; and a ratchet wheel having a center portion fastened for rotational movement about said central pivot point, and having a plurality of circumferential teeth for alternate engagement with said first and second pawls; whereby lever arm operation in one direction engages said pawl with said ratchet wheel teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction. 12. The drive of claim 11, said lever arm including: means for adjusting connecting rod spacing at said second pivot point from said first pivot point to selectably vary resulting connecting rod movement corresponding to reciprocal lever arm movement, whereby a continuously varying drive mechanism gear ratio is provided. 13. The drive of claim 12, said lever arm including a first portion to which said connecting rods are pivotally secured and a telescoping second portion having an end portion secured to said first pivot point, said means for adjusting including: an actuating rod positioned within a hollow inner portion of said lever arm at said hand grip portion thereof and including an actuator portion extending outwardly past said first lever arm end portion coaxial therewith and including a conical tip portion; biasing means for maintaining said actuator portion in said extended position; detent means coincident with said conical tip for securing said first lever arm portion to said telescoping second lever arm portion; and biasing means for maintaining said detent means within abutment of said actuating rod conical tip portion; whereby depression of said actuating rod within said lever arm forces said actuating rod tip portion to displace said detent to thereby allow free telescoping motion of said second lever arm portion relative to said first lever arm portion, such that said connecting rods associated with said first lever arm portion are accordingly moved nearer to or farther from said lever arm pivot point associated with said telescoping second lever arm portion. 14. The drive of claim 11, further comprising: bayonet mount means adapted for removably fastening said drive mechanism to said drive wheel. 15. The drive of claim 11, said pawls each further comprising: biasing means, for withdrawing said pawl from engagement with said ratchet wheel teeth in the absence of a countering drive force supplied by an associated one of said connecting rods. 16. The drive of claim 11, said pawls being operable to alternately engage with said ratchet wheel teeth when said associated connecting rods are operated in substantially opposite directions, said first pawl being engaged in a first connecting rod direction, said second pawl being engaged in an opposite connecting rod direction, thereby providing for transfer of drive energy to said ratchet wheel during both forward and a rearward reciprocating lever arm stroke. 17. The drive of claim 16, said pawls being biased by connecting rods to engage with said ratchet wheel teeth when pivoted in an engagement direction. 18. The drive of claim 11, each pawl being operable between a first extreme position and a second extreme position, corresponding to extremes of lever arm movement, each pawl including a bump stop to damp abutment of one pawl with the other as well as disengage the pawls at each extreme of pawl movement. 19. The drive mechanism of claim 11 and including two connecting rods, two pawls, and two radial cranks, whereby lever arm operation in the first direction engages the first pawl with said ratchet wheel teeth for translation of reciprocal lever arm movement to rotational ratchet wheel movement in a drive direction, and whereby lever arm operation in the second, opposite direction engages the second pawl with said ratchet wheel teeth, and disengages said first pawl therefrom, for translation of reciprocal lever arm movement to rotational ratchet wheel movement in said drive direction.