Center-of-gravity tilt-in-space wheelchair

• US 20040188979A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Active Grant

• Current Assignee: Sunrise Medical Us LLC (Sunrise Medical Incorporated)
• Original Assignee: Sunrise Medical Hhg Incorporated (Sunrise Medical Incorporated)
• Inventors: Killebrew, Allen B., Schneider, Richard, Hanson, Wayne, Schreiber, Philip, Lindquist, Steven L., Whelan, Tom, Bernatsky, Todd, Houtart, Jerry, Nordquist, Mike
• Granted Patent: US 7,007,965 B2
• Time in Patent Office: Days
• US Class Current: 280/304.1
• CPC Class Codes: A61G 5/045 Rear wheel drive
• CPC Class Codes: A61G 5/1059 adjusting the height of the seat
• CPC Class Codes: A61G 5/1062 adjusting the width of the seat
• CPC Class Codes: A61G 5/107 positioning the whole seat forward or rearward
• CPC Class Codes: A61G 5/1075 tilting the whole seat backwards tilting forwards for standing-up or sitting-down aids A61G5/14
• CPC Class Codes: A61G 5/12 Rests specially adapted therefor, e.g. for the head or the feet

Abstract

A center-of-gravity tilt-in-space wheelchair includes a base, a seat for supporting an occupant, and tracks supporting the seat for selective seat movement relative to the base. Wheels are adapted to support the base relative to a supporting surface. The tracks serve as rolling or sliding surfaces that allow the seat to rotate with respect to the base. Each track has a constant-radius arc with a focal point that is adapted to be coincident with the center of gravity of the wheelchair occupant. A low-friction supports the base relative to the seat. The low-friction support may include low friction elements that mate with the tracks to support for the tracks. The support can be adjustable to permit the overall tilt angle range of the tracks to be adjusted. The wheelchair seat can be adjusted to maintain the focal point of the constant-radius arc of the tracks coincident with the center of gravity of the wheelchair occupant. The front and rear wheels can be adjusted fore and aft relative to the focal point. A coupling includes plates having upper ends operatively attached to one another with seat canes therebetween and lower ends releasably attached relative to the side tubes. The lower ends can be movable in a longitudinal direction relative to the side tubes while remaining operatively connected to the side tubes. A base frame can include side frames having an offset at a front end and a caster housing supported by the offset. The offset is directed up to minimize the height of the side frames and down to maximize the height.

Claims

1. A wheelchair comprising:

a base;

a plurality of wheels that are adapted to support the base relative to a supporting surface;

a seat for supporting an occupant; and

one or more tracks supporting the seat, the one or more tracks serving as a rolling or sliding surface that allows the seat to rotate with respect to the base, the one or more tracks having a constant-radius arc with a focal point that is adapted to be coincident with the center of gravity of the wheelchair occupant.

2. A wheelchair according to claim 1 wherein the track position is adjustable fore and aft with respect to the base and the front and rear wheels so that the position of the focal point relative to the front and rear wheels may be selectively changed.

3. A wheelchair according to claim 1 wherein both the front and rear wheels are adjustable fore and aft relative to the focal point so that the distance between the front and rear wheels can be shortened or lengthened.

4. A wheelchair according to claim 1 further comprising a low friction support assembly supporting the seat relative to the base, the low friction support assembly that is adjustable to change an overall range of seat tilt by fixing the low friction support assembly to the base at different angular orientations.

5. A wheelchair according to claim 1 further comprising one or more protrusions that are adapted to be engaged with one or more recesses in the one or more tracks so that when the protrusions enter the recesses to lock the tracks into an angular position and are adapted to be retracted from the recesses so that the seat can be rotated to a different tilt angle relative to the base.

6. A wheelchair according to claim 1 wherein the one or more tracks comprise one or more curved tubes.

7. A wheelchair according to claim 6 further comprising pivoting plates with holes therein situated about each of the one or more curved tubes, the holes being slightly larger than the diameter of the tube so that the tube can pass freely through the plates when the plates are pivoted so that axes of the holes are aligned with the arc of the tube and so that the tube is prevented from passing through the plates when the plates are pivoted so that the axes of the holes are not aligned with the arc of the tube.

8. A wheelchair according to claim 1 further comprising a low-friction support assembly comprising one or more rollers that support each of the one or more tracks so that the one or more tracks are free to rotate in a direction of rotation upon the one or more rollers but are otherwise constrained by the rollers from moving traverse to the direction of rotation.

9. A wheelchair according to claim 8 wherein the one or more tracks and the corresponding one or more rollers each has at least a portion thereof that has a mating cross-sectional contour that prevent transverse movement of the rollers.

10. A wheelchair according to claim 1 wherein the seat is an element of an adjustable seating system that allows the center of gravity of a wheelchair occupant to be moved fore and aft in order to locate the center of gravity at the focal point of the constant-radius arc.

11. A wheelchair according to claim 10 wherein the adjustable seating system comprises a seat frame that, in addition to the seat, includes a backrest and a footrest assembly, all of which are adapted to be adjusted fore and aft with respect to the focal point.

12. A wheelchair according to claim 11 wherein the seat frame further comprises laterally spaced side tubes and the backrest comprises laterally spaced canes supported relative to the side frame by couplings, the couplings including an assembly of plates having upper ends operatively attached to one another and lower ends attached to the side tubes so that the lower ends of the plates can move relative to the side tubes while remaining operatively connected to the side tubes.

13. A wheelchair according to claim 1 further comprising a motor that is operatively connected between the base and the seat so that the seat can be rotated about the center of gravity of a wheelchair occupant.

14. A wheelchair according to claim 1 further comprising motors operatively connected to one or more of the plurality of wheels for driving the wheels operatively connected thereto.

15. A wheelchair comprising:

a base;

a plurality of wheels that are adapted to support the base relative to a supporting surface;

a seat;

one or more tracks having a constant radius arc supporting the seat for movement relative to the base; and

a low-friction support supported by one of either the base or the seat, the low-friction support comprising low friction elements that mate with the one or more tracks to provide sole support for the one or more tracks.

16. A wheelchair comprising:

a base;

a plurality of wheels that are adapted to support the base relative to a supporting surface;

a seat;

one or more tracks having a constant radius arc supporting the seat for movement relative to the base; and

a low friction support assembly supported by one of either the base or the seat, the support permitting an overall tilt angle range of the one or more tracks to be adjusted.

17. A wheelchair comprising:

a base;

a plurality of wheels that are adapted to support the base relative to a supporting surface;

a seat for supporting an occupant;

one or more tracks supporting the seat, the one or more tracks having a constant-radius arc with a focal point that is adapted to be coincident with the center of gravity of a wheelchair occupant; and

the wheelchair seat being structured to be adjusted while maintaining the focal point of the constant-radius arc of the one or more tracks coincident with the center of gravity of the wheelchair occupant.

18. A wheelchair comprising, in combination:

seat back canes;

side tubes; and

plates having upper ends that are operatively attached to one another with the canes secured therebetween and lower ends that are releasably attached relative to the side tubes and movable in a longitudinal direction relative to the side tubes while remaining operatively connected to the side tubes to permit the position of the canes to be longitudinally adjusted relative to the side tubes.

19. The wheelchair according to claim 18 wherein the upper ends of the plates are operatively attached to one another with a first fastener which is also adapted to function as a pivot for pivotal movement of the canes relative to the side tubes to permit the canes to fold downward in the direction of the side tubes.

20. The wheelchair according to claim 19 further comprising a second fastener spaced apart from the first fastener, the second fastener attaching the plates to one another with the canes therebetween and being selectively engaged by a spring-biased piston to lock the canes in a fixed position and prevent the canes from folding downward.

21. The wheelchair according to claim 20 wherein opposing bosses are supported relative to the side tubes, the lower ends of the plates being configured to receive the bosses and retain the bosses when the upper ends of the plates are attached to one another by at least one of the first and second fasteners, the bosses functioning as pivots about which the angle of the canes can be adjusted, the bosses being selectively movable in the longitudinal direction relative to the side tubes.

22. The wheelchair according to claim 21 further comprising an arcuate arrangement of scalloped holes in the plates in spaced relation to the bosses and a third fastener that is adapted to engage one of the scalloped holes to selectively adjust the angle of the canes relative to the side tubes.

23. The wheelchair according to claim 21 wherein the third fastener is adapted to engage one of the scalloped holes so that the angle of the canes relative to the side tubes remains the same as the plates are moved in the longitudinal direction relative to the side tubes.

24. A wheelchair base frame comprising:

side frames having a front end;

an offset at the front end of each of the side frames; and

a caster housing supported by each of the offset, the side frames being selectively positioned to direct the offset up to minimize the height of the side frames relative to a supporting surface and direct the offset down to maximize the height of the side frames relative to a supporting surface.

25. The frame according to claim 24 further comprising an axle sleeve supported relative to each one of the side frames tubes, the axle sleeves being selectively positioned at various distances relative to the side frames to vary the distance of the side frames relative to the supporting surface.