Patent Application
20080106059
The present invention relates generally to manual transport wheelchairs. More particularly, the present invention relates to a folding wheelchair of light-weight and high weight capacity.
Numerous health patients require wheelchair assistance when walking, especially over long distances, but also desire an active lifestyle. One type of wheelchair that is commonly used is a transport wheelchair (referred to hereinafter interchangeably as the “wheelchair” or the “transport wheelchair”), which is also known as a “companion chair” because it generally has smaller wheels and requires a person to push the wheelchair from behind. The wheelchair must be sufficiently strong to safely support the weight of a wheelchair user and, yet, it must be light enough to allow easy transportation. For example, an elderly person may require the use of the wheelchair when engaging in activities outside of the home, e.g., going to a mall, visiting a park, eating dinner at a restaurant, etc. To be able to engage in the desired activities, it is necessary to transport the wheelchair to the location of the desired activities, e.g., loading and unloading the wheelchair to and from the trunk of a car. In many cases, the person transporting the chair is the spouse of the wheelchair user. The spouse may be an elderly person that may have difficulty lifting a heavy wheelchair. In other cases, even if the person transporting the chair may be an employed caretaker handling the wheelchair may still be cumbersome.
Although attempts have been made to provide light-weight transport wheelchairs, these wheelchairs have numerous problems. One problem associated with some current wheelchairs is that they generally weigh over nineteen pounds. Thus, these so called “light-weight” wheelchairs may be deemed as being “too heavy” by a person of advanced age. Any reduction in weight, e.g., even a few ounces, may be deemed of considerable value to the wheelchair users and transporters because the wheelchair can be more portable than current wheelchairs.
Another problem associated with some current wheelchairs is that the wheelchairs may become unstable. An improper reduction of weight, such as eliminating one or more structural member, may lead to an unstable wheelchair that may malfunction under particular conditions. For example, while the unstable wheelchair may function adequately on a flat and generally horizontal surface, the unstable wheelchair may tip over when traversing an inclined surface. Thus, weight reduction requires more than simply eliminating parts or using smaller structural members.
Yet another problem associated with current transport wheelchairs is that they have a generally low weight capacity. For example, some of these wheelchairs have a maximum weight capacity of only about 225 pounds. Thus, these wheelchairs fail to provide adequate support and stability for individuals having a weight that exceeds the maximum weight capacity. These wheelchairs also fail to adequately support individuals of a smaller weight than the maximum weight capacity if these individuals transport additional items, such as grocery bags, resulting in a combined weight that is greater than the maximum weight capacity.
Therefore, there exists a need for a transport wheelchair that is stable, that has a low weight, and that has a high weight capacity in comparison to current transport wheelchairs, while maintaining the look and feel of a true wheelchair.
According to one embodiment, a manual transport wheelchair for transporting a person is changeable between a transport position and a folded position. The wheelchair has two side frames coupled by a single scissor frame that is movable to change the wheelchair between the transport position and the folded position. The wheelchair has a weight capacity-to-weight ratio of at least nineteen.
According to another embodiment, a method of manufacturing a manual transport wheelchair includes coupling a first side frame to a second side frame via a single scissor frame, the scissor frame being movable to change the wheelchair between a transport position and a folded position. A seating area is attached to the scissor frame, the seating area having a weight capacity of at least three hundred pounds and the wheelchair having a weight of less than sixteen pounds. The seating area is supported on a plurality of support tabs when the wheelchair is in the transport position.
According to a further embodiment, a wheelchair is movable between a transport position for transporting a person and a folded position for storing the wheelchair. The wheelchair includes a seating area, a pair of side frames, a plurality of support tabs, and a single centrally located scissor frame. The seating area supports the person in the seated position. The pair of side frames has respective front members and rear members, the front members being respectively coupled to the rear members via longitudinal upper members and longitudinal lower members. The plurality of support tabs is attached to the longitudinal upper members for supporting the seating area when the wheelchair is in the seated position. The scissor frame couples the pair of side frames to each other and is movable to change the wheelchair between the seated position and the folded position. The wheelchair has a maximum weight of less than sixteen pounds and a weight capacity-to-weight ratio of at least nineteen.
The above summary of the present invention is not intended to represent each embodiment or every aspect of the present invention. The detailed description and Figures will describe many of the embodiments and aspects of the present invention.
The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings.
While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
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The side frame 202a includes a front member 206a and a rear member 208a that are coupled via a lower longitudinal member 210a and an upper longitudinal member 212a. The front member 206a has a lower end that extends beyond an intersection between the front member 206a and the lower longitudinal member 210a. The rear member 208a has a lower end that extends beyond an intersection between the rear member 208a and the lower longitudinal member 210a. The lower end of the rear member 208a is closer to a horizontal floor plane than the lower end of the front member 206a.
The upper longitudinal member 212a is generally angled rearwardly such that a front end (which is coupled to the front member 206a) is higher than a rear end (which is coupled to the rear member 208a) relative to the horizontal floor plane. Having the upper longitudinal member 212a angled with respect to the horizontal floor plane minimizes the likelihood that the user will slip or fall from the wheelchair 100.
The left side frame 202a further includes an armrest member 214a having a horizontal end coupled to the rear member 208a and a vertical end coupled to the upper longitudinal member 212a, the horizontal end and the vertical end being connected via a slanted member. The slanted member has a front end that is located lower (or closer to the upper longitudinal member 212a) than a rear end. The slanted member forms one continuous member with the horizontal end and the vertical end of the armrest member 214a (e.g., it does not require welding) to minimize the weight of the armrest member 214a, while maintaining a high structural strength. Alternatively, the slanted member is a separate member from the horizontal end and the vertical end of the armrest member 214a (e.g., it requires welding). The slanted member of the armrest member 214a can be used by a wheelchair user to support himself or herself when changing between a seated position and a standing position. An armrest pad 215a is coupled to the armrest member 214a for comfort of the user.
The left side frame 202a also includes a pair of supporting tabs, having a front supporting tab 216a and a rear supporting tab 218a. The front supporting tab 216a is located near the front member 206a and the rear supporting tab 218a is located near the rear member 208a. The supporting tabs 216a, 218a have a general “C” shape and are made from aluminum or aluminum alloys. Further, the supporting tabs 216a, 218a include an outer non-metallic sleeve (e.g., polyurethane). Because the upper longitudinal member 212a is angled rearwardly, the front supporting tab 216a is higher relative to the horizontal floor plane than the rear supporting tab 218a. In alternative embodiments, the number, shape, or material of the supporting tabs 216a, 216b, 218a, 218b may vary based on particular design requirements.
A cane tube 220a is coupled to the rear member 208a via a latching mechanism 222a at an upper end of the rear member 208a. The cane tube 220a includes an upper end that is flared outwards, relative to the interior of the wheelchair 100, and that includes a push grip 224a. The latching mechanism 222a permits the cane tube 220a to rotate from an upright position (as shown) to a bent downward position (shown in
A front caster 226a and a rear wheel 228a are attached respectively to the lower ends of the front member 206a and the rear member 208a. The front caster 226a is attached to the front member 206a by inserting a caster shaft 230a into the lower end of the front member 206a. Alternatively, the front caster 226a can be attached to the wheelchair 100 using various fasteners. The rear wheel 228a is attached to the rear member 208a via a central region of the wheel. The rear wheel 228a can have an outer diameter such that the outer periphery of the rear wheel 228a is lower than the intersection of the rear member 208a and the lower longitudinal member 210a.
A brake mechanism 232a is mounted on the rear member 208a near and above the outer periphery of the rear wheel 228a. The brake mechanism 232a is used by a person transporting the wheelchair 100 to securely fix the rear wheel 228a while in a stopped position.
The scissor frame 204a includes a pair of cross-members 234a, 234b that are pivotably connected to each other at a central pivoting point 236. The lower ends of the cross-members 234a, 234b are pivotably attached respectively to the lower longitudinal members 210a, 210b. A couple of pivoting arms 238a, 238b are attached respectively, at one end, to the cross-members 234a, 234b and, at another end, to the upper longitudinal members 212a, 212b. The pivoting arms 238a, 238b are pivotable at both ends.
The scissor frame 204 further includes a pair of seat supports 240a, 240b that are securely attached to a respective upper end of the cross-members 234a, 234b. When the wheelchair 100 is in the transporting position (e.g., the user is seated in the chair), the seat supports 240a, 240b are supported by the four supporting tabs 216a, 216b, 218a, 218b.
The wheelchair 100 includes a seating area 250, which is attached at each end to a respective one of the seat supports 240a, 240b, a lower back area 252, which is attached to the rear members 208a, 208b, and an upper back area 254, which is attached to the cane tubes 220a, 220b. The seating area 250, the lower back area 252, and the upper back area 254 are made from a flexible material, such as any upholstery material. For example, the material can be a vinyl material.
A pair of optional leg riggings 260a, 260b for supporting the user's legs are attachable respectively to the front members 206a, 206b. The leg riggings 260a, 260b are removable, height adjustable, and pivotable. The weight of the leg riggings 260a, 260b, which is about 1.4 pounds per leg rigging, is not included in the weight of the chair, which, as mentioned above is under 16 pounds, and, in some embodiments, at most 15.6 pounds.
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The wheelchair 100 has a plurality of structural reinforcements, including a front reinforcement tubing 370a, a rear reinforcement tubing 372a, a front reinforcement weld 374a, and a rear reinforcement weld 376a. The front reinforcement tubing 370a is located within a front portion of the lower longitudinal member 210a and the rear reinforcement tubing 372a is located within the rear member 208a, near the rear wheel 228a attachment point. The front reinforcement weld 374a is located below the front end of the lower longitudinal member 210a, at the intersection with the front member 206a. The rear reinforcement weld 376a is located below the rear end of the lower longitudinal member 210a, at the intersection with the rear member 208a. The structural reinforcements provide structural support for the light-weight wheelchair 100 for maintaining a high weight capacity.
The tubular members of the wheelchair 100 (e.g., the front members 206a, 20b, the rear members 208a, 208b, the lower longitudinal members 210a, 210b,the upper longitudinal members 212a, 212b, the cross-members 234a, 234b, etc.) are optionally made using aluminum tubing having a diameter thickness of 2 millimeters (0.08 inches) or less. For example, according to one embodiment, the lower longitudinal member 210a has a length of 448 millimeters (17.64 inches), a diameter of 10 millimeters (0.39 inches), a diameter thickness of 2 millimeters (0.08 inches), and is made using aluminum 6061T4. Similarly, according to an alternative embodiment, the rear member 208a (from its lower end to the central axis of the upper longitudinal member 212a) has a length of 335 millimeters (13.19 inches), a diameter of 12 millimeters (0.47 inches), a diameter thickness of 2 millimeters (0.08 inches), and is made using aluminum 6061T4. The portion of the rear member 208a from its lower end to the central axis of the lower longitudinal member 210b (i.e., the intersection between the rear member 208a and the lower longitudinal member 210b) is 127 millimeters (5.00 inches), according to yet another alternative embodiment. According to one embodiment of the present invention, the wheelchair 100 has an overall height dimension of 876.3 millimeters (34.5 inches) and an overall front-to-back length of 723.9 millimeters (28.5 inches).
Optionally, all the structural members of the wheelchair 100 (e.g., all the members of the side frames 202a, 202b) are made using aluminum or aluminum alloys. In alternative embodiments, other light-weight materials may be used.
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In response to the pulling force, the cross-members 234a, 234b and the pivoting arms 238a, 238b pivot such that the seat supports 240a, 240b separate from their resting position on the support tabs 216a, 216b, 218a, 218b. Specifically, the lower ends of each of the cross-members 234a, 234b pivot about the respective lower longitudinal member 210a, 210b, and the cross-members 234a, 234b pivot about each other at the central pivoting point 236. Similarly, the pivoting arms 238a, 238b pivot at one end relative to the respective upper longitudinal member 212a, 212b and at another end relative to the respective cross-member 234a, 234b. The folding motion generally stops when the pivoting motion of the pivoting arms 238a, 238b is stopped by contact with the respective upper longitudinal members 212a, 212b.
In the folded position, the side frames 202a, 202b are separated by a much smaller distance than in the transporting position. For example, according to one embodiment, the side frames 202a, 202b are separated by a distance of about 500 millimeters (20 inches) in the transporting position and by a distance of about 140 millimeters (5.5 inches) in the folded position.
In alternative embodiments, the wheelchair 100 includes one or more optional features. For example, the wheelchair 100 optionally includes a user seatbelt and/or a cup holder knob coupled to a member of one or more of the side frames 202a, 202b. The user seatbelt can be attached to the lower back area and the cup holder know can be screwed on the upper longitudinal member 212a, 212b.
The wheelchair 100 has been successfully tested to withstand a weight of at least 300 pounds. For example, a fatigue drop test was performed in which the wheelchair 100 was subjected to 6,6667 cycles with a 300 pound weight capacity. During the drop test, the wheelchair 100 was supported in a drop test machine to simulate the wheelchair 100 being supported on a horizontal plane (i.e., having both the front casters 226a, 226b and the rear wheels 228a, 228b on a horizontal plane). The wheelchair 100 was, then, dropped about 50 millimeters (1.97 inches), plus or minus 5 millimeters (0.197 inches), onto a rigid horizontal plane. No failure was found during the test.
Similarly, another fatigue test (referred to as a two-drum test) was performed in which the wheelchair 100 was positioned on two drums that are separated by a distance such that corresponding axles of the casters 226a, 226b and wheels 228a, 228b are directly above respective axles of the drums (within a tolerance of about plus/minus 10 millimeters (0.394 inches). Specifically, the wheelchair 100 was positioned with its driven wheels, e.g., the rear wheels 228a, 228b, on a reference drum and its casters 226a, 226b on the second drum. The wheelchair 100 was constrained longitudinally by devices attached to the axles of the rear wheels 228a, 228b (or, alternatively, by devices attached to the wheelchair 100 as close to the axles of the rear wheels 228a, 228b as possible) such that lateral movement of the wheelchair 10 was limited to plus/minus 50 millimeters (1.97 inches) from a mid-position of the wheelchair 10. The reference drum was operated at a speed of about 1.0 meters/second (plus/minus 0.1 meters/second). The wheelchair 100 was subjected to 200,000 cycles with a 300 pound weight capacity. No failure was found during this test. Further, the wheelchair 100 was approved to meet the requirements prescribed under U.S. Food and Drug Administration (FDA) ISO 7176-8.
While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. For example, instead of attaching the rear wheel 228a to the rear member 208a via a central region of the wheel, the rear wheel 228a may be attached to other members of the wheelchair 100 or to other regions of the wheel using known fastening means. In another example, instead of mounting the brake mechanism 232a to the rear member 228a near and above the outer periphery of the rear wheel 228a, the brake mechanism 232a may be mounted on other members of the wheelchair 100 and may be used to restrain movement of one or more of the front casters 226a, 226b. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the invention, which is set forth in the following claims.
