Mobility aid

A wheelchair includes at least one side frame connected to a front caster assembly, and a cross-brace assembly. The cross-brace assembly includes a cross-brace member; at least one rear caster assembly connected to the cross-brace member; at least one main drive wheel axle tube fitting connected to the cross-brace member; and at least one arm connected to the cross-brace member. The at least one arm is pivotally connected to the at least one side frame through a pivot joint.

BACKGROUND OF THE INVENTION

Wheelchairs and scooters are an important means of transportation for a significant portion of society. Whether manual or powered, these vehicles provide an important degree of independence for those they assist. However, this degree of independence can be limited if the wheelchair is required to traverse obstacles such as, for example, curbs that are commonly present at sidewalks, driveways, and other paved surface interfaces. This degree of independence can also be limited if the vehicle is required to ascend inclines or descend declines.

BRIEF SUMMARY OF THE INVENTION

In one aspect the invention relates to a wheelchair including at least one side frame connected to a front caster assembly, and a cross-brace assembly. The cross-brace assembly includes a cross-brace member; at least one rear caster assembly connected to the cross-brace member; at least one main drive wheel axle tube fitting connected to the cross-brace member; and at least one arm connected to the cross-brace member. The at least one arm is pivotally connected to the at least one side frame through a pivot joint.

In another aspect the invention relates to a wheelchair including a left side frame connected to a left front caster assembly, and a right side frame connected to a right front caster assembly, the left side frame and the right side frame together supporting a seat of the wheelchair. A cross-brace assembly extends across the wheelchair, and includes a cross-brace member having left and right main wheel fittings for supporting left and right main wheels of the wheelchair. A left arm is connected to the cross-brace member, the left arm being pivotally connected to the left side frame through a left pivot joint. A right arm is connected to the cross-brace member, the right arm being pivotally connected to the right side frame through a right pivot joint. A rear caster arm extends from the cross-brace member and supports a rear caster assembly.

DESCRIPTION OF PREFERRED EMBODIMENTS

The following includes definitions of exemplary terms used throughout the disclosure. Both singular and plural forms of all terms fall within each meaning:

“Attachment” as used herein includes, but is not limited to, something that directly or indirectly attaches one thing to another including, for example, a tie, band, fastener, clamp, or pin.

“Substantially horizontal” as used herein includes, but is not limited to, being largely but not wholly: in the plane of a horizon or primary axis; of, relating to, or near the horizon; or parallel to or in the plane of the horizon; at right angles to a vertical line. “Substantially horizontal” as used herein also includes, but is not limited to, being wholly: of, relating to, or near the horizon; parallel to or in the plane of the horizon; or at right angles to a vertical line. “Substantially horizontal” further includes, but is not limited to, angular deviations up to and including 45 degrees from a horizontal line or axis.

“Substantially vertical” as used herein includes, but is not limited to, being largely but not wholly: perpendicular to the plane of the horizon or to a primary axis; upright; or located at right angles to the plane of a supporting surface. “Substantially vertical” as used herein also include, for example, being wholly: perpendicular to the plane of the horizon or to a primary axis; upright; or located at right angles to the plane of a supporting surface. “Substantially vertical” further includes, but is not limited to, angular deviations up to and including 45 degrees from a vertical line or axis.

“Attach” or “connect” as used herein includes, but is not limited to, directly or indirectly fastening, securing, joining, coupling, affixing, appending, adding, or binding two or more things or components together.

Referring now toFIGS. 1A,1B, and1C, one embodiment of a wheelchair100is shown. Wheelchair100includes a seat frame102having an L-shaped section104and a backrest section106. A crossbar107joins a second similarly configured portion of the side frame102. A seat cushion108is configured to rest on seat frame102so as to provide support to a user. Backrest106may be an adjustable backrest that can tilt with respect to L-shaped section104of the seat frame to thereby vary the angle between the two components. A backrest cushion110may also be provided on backrest106.

Wheelchair100also includes side frame112. Side frame112has a substantially L-shaped configuration that includes a substantially horizontal section113and bracket116. Near the forward portion of side frame112is a front caster assembly134that includes a caster head tube, axle and wheel.

Bracket116depends upwardly from side frame section113to form a raised pivot connection and includes a stop117that may be engaged by axle tube136, as will be discussed below. Bracket116is connected to side frame section113via a plurality of apertures114such as, for example, apertures118and120. These apertures accept removable fasteners that allow bracket116to be connected along the length of side frame112at a plurality of positions for center-of-gravity adjustments with respect to the wheelchair and/or wheelchair occupant. If such adjustments are not desired, bracket116can be more permanently connected or integrated into side frame112.

An arm, or support arm,124is connected to bracket116via a joint122. Joint122is a pivot joint and allows side frame112to pivot with respect to arm124. Joint122can include a suspension to resist or dampen pivoting motion. Examples of such suspension include, but are not limited to, resilient members such as “rosta”-type elastomeric bearings or spring/shock absorbers placed between bracket116and arm124.

A first portion of arm124is connected to bracket116at pivot joint122and a second portion of arm124is connected to a cross-brace member or axle tube136, which forms a part of cross-brace assembly135. Axle tube136includes axle tube fittings126for attaching a drive wheel128to the wheelchair100. In the embodiment shown, axle tube136is mounted above a portion of bracket116that includes stop117. The space between axle tube136and stop117provides side frame112with a range of tilt angle when raising front caster assembly134. This range of tilt or pivot can assist in traversing obstacles by allowing the front caster assembly to rise from a supporting surface of the wheelchair.

This pivoting motion allows side frame112to raise front caster assembly134to assist in traversing obstacles. Seat frame102also pivots by virtue of its connection to side frame112(the seat frame102is fixed for movement with the side frame112in the illustrated embodiment). The side frame's motion is limited by the engagement between stop117and axle tube136. Stop117has a curved section that at least approximately matches the shape of axle tube136and is located so as to allow engagement of axle tube136. While stop117is shown on bracket116, it can be a separate component mounted onto or integrated into side frame112. Also, stop117need not have an engagement portion that approximates the shape of axle tube136. The engagement portion can be any shape suitable for engaging axle tube136to limit the pivoting motion of side frame112.

A caster arm130is connected to axle tube136between arms124. Caster arm130has a first portion connected to a rear caster assembly132that includes a caster head tube, axle, and wheel. A second portion of caster arm130is connected to axle tube136thereby connecting rear caster assembly132to axle tube136. In alternative embodiments, caster arm130may be connected to axle tube130so as to allow some degree of movement between axle tube136and rear caster assembly132. Caster arm130is preferably centrally located (laterally) on the wheelchair100.

Axle tube136includes a body having first and second distal portions that each include an arm124. A third portion of the axle tube136that is between the first and second distal portions includes a connection to caster arm130. A drive wheel axle insert/fitting126is also provided proximate the first and second distal portions for attaching the main drive wheels of the wheelchair. In this arrangement, the axle tube136acts as a cross-brace between the side frames of wheelchair100. In this embodiment, the combination of axle tube136and caster arm130form a T-shaped frame member for wheelchair100to which side frame112is pivotally connected. In other embodiments, more than one caster arm130can be connected to axle tube136.

In alternate embodiments, axle tube136may be omitted. For example, a cross-brace having arms124and caster arm130connected in the same position as that shown on axle tube136can be utilized. In such an arrangement, drive wheel axle fittings or sleeves are also connected to the cross-brace such as, for example, by a bracket depending away from the cross-brace.

In operation, the weight of the wheelchair and occupant is distributed between the front and rear caster assemblies and the main drive wheels. When side frame112is subject to a downward force or load behind pivot joint122or an upward force or load forward of pivot joint122, side frame112will pivot so as to raise front caster assembly134from its supporting surface. This weight supported by the front caster assembly134is transferred to the main drive wheels and the rear caster assembly. The amount of weight transferred to the main drive wheels, as compared to the amount of weight transferred to the rear caster assembly, depends on the ratio between (a) the distance from the rear caster assembly132to the pivot joint122and (b) the distance from the main drive wheel axle connection126to the pivot joint122. Hence, adjustment of the location of pivot joint122between the rear caster assembly132and the main drive wheel axle connection126varies the weight distribution and transfer. Raising the smaller wheels of front caster assembly134in effect moves them out of the way so that the larger drive wheels of the wheelchair can be more easily used to overcome large obstacles.

FIGS. 2A and 2Billustrate a second embodiment in the form of a wheelchair200. Wheelchair200is substantially similar to wheelchair100, except that it includes a different embodiment of a caster arm in the form of caster arm201. Caster arm201includes, for example, an axle tube mount203having first and second flanges210and212, a resilient member202, and a caster mount204having first and second caster mount flanges206and208. In one embodiment, resilient member202is a leaf spring that can bend when loaded by a force or weight and return to its unloaded position when the force or weight is removed. In other embodiments, resilient member202can be a spring or combination spring/shock absorber.

On one end, resilient member202is connected to axle tube136via attachment to flanges210and212. On a second end, resilient member202is connected to rear caster assembly132via attachment to flanges206and208. The attachment can be a removable attachment such as, for example, by removable fasteners that are received in apertures of the flanges. This arrangement allows for the attachment and removal of resilient members202that are of different resiliency and characteristic. In alternative embodiments, resilient member202can be directed connected to axle tube132and rear caster assembly132via welding or brazing. In this regard, resilient member202provides a degree of suspension between axle tube136and rear caster assembly132that allows rear caster assembly132to move with respect to its position versus axle tube132.

FIGS. 3A and 3Billustrate a third embodiment in the form of a wheelchair300. Wheelchair300is substantially similar to wheelchair100, except that it includes a different embodiment of a caster arm in the form of caster arm301. Caster arm301is substantially similar to caster arm130, except that it includes a non-linear geometry. For example, caster arm301includes a curved section302.

FIGS. 4A-4Hillustrate a fourth embodiment in the form of a wheelchair400. The wheelchair400includes a releasable link402between the seat frame404and the side frame of the wheelchair. The presence of the releasable link402enables folding (collapsing) of the wheelchair400to a compact shape, as shown schematically in the series of view4A-4H.

InFIG. 4A, the wheelchair400is shown fully assembled. InFIG. 4B, the main wheels408are removed from the wheelchair400but the seat frame404and the side frame406are not altered.

InFIG. 4C, the link402is opened or released, allowing the seat frame404to be pivoted upward relative to the side frame406. InFIGS. 4D-4F, the backrest410and the caster arm412are pivoted to be more parallel with the seat frame404and the side frame406. The caster arm412is swung up and forward, in between the two sides of the side frame406, which action is made easier because the caster arm is a single centrally located arm.

Finally, inFIGS. 4G and 4H, the seat frame404and the side frame406are pivoted closer to each other, resulting in the wheelchair400having a compact folded shape.

FIGS. 5A-5Dillustrate the simulated operation of the wheelchair400in backing up (being pulled up) a set of steps. This operation is enabled as the rear caster arm412is pivotable upward relative to the seat frame404to a degree sufficient to enable pulling the wheelchair400backward up a set of steps. This action is made easier because the caster arm412is a single centrally located arm.

InFIG. 5A, the wheelchair400is level and adjacent to the set of steps. InFIG. 5B, the caster arm412is raised up, relative to the side frame406and the seat frame404, to enable sufficient clearance for the drive wheels of the wheelchair400to engage the set of steps.

FIGS. 5C and 5Dillustrate how the caster wheel on the caster arm412remains above the plane of the steps (as indicated by the dot-dash line) while the wheelchair400is being backed up (pulled up) the set of steps.

While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, seat frame or side frame can have different geometries from that shown herein, arm124can including a plurality of apertures therein to allow pivot joint122to be moved or adjusted along arm124, and clamps can be used to facilitate connections between components. Also, the present invention provides a wheelchair having the feel and benefits of a rigid chair, while still being collapsible but not using the collapsible cross-frames typically used. Therefore, the inventive concept, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.