U.S. patent application number 16/799396 was filed with the patent office on 2020-06-18 for manual wheelchair system for improved propulsion and transfers.
The applicant listed for this patent is United States Government as Represented by the Department of Veterans Affairs Regents of the University of Minnesota. Invention is credited to Gary D. GOLDISH, Andrew H. HANSEN.
Application Number | 20200188200 16/799396 |
Document ID | / |
Family ID | 51524132 |
Filed Date | 2020-06-18 |
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United States Patent
Application |
20200188200 |
Kind Code |
A1 |
HANSEN; Andrew H. ; et
al. |
June 18, 2020 |
MANUAL WHEELCHAIR SYSTEM FOR IMPROVED PROPULSION AND TRANSFERS
Abstract
A manual wheelchair including a collapsible frame having a first
lateral member that is connected to first and second braces at
their respective first ends. A drive wheel axel extends along a
first axis of rotation and engages a drive wheel, the first brace,
and a portion of a transmission. A push rim axel extends along a
second axis of rotation and engages a push rim wheel, the second
brace, and a portion of the transmission, which transmits rotation
of the push rim to rotation of the drive wheel. The collapsible
frame additionally includes a second lateral member that is
connected to the first and second braces as their respective second
ends. The first and second braces are configured to release the
second lateral member to collapse the manual wheelchair.
Inventors: |
HANSEN; Andrew H.;
(Minneapolis, MN) ; GOLDISH; Gary D.;
(Minneapolis, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United States Government as Represented by the Department of
Veterans Affairs
Regents of the University of Minnesota |
Washington
Minneapolis |
DC
MN |
US
US |
|
|
Family ID: |
51524132 |
Appl. No.: |
16/799396 |
Filed: |
February 24, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15269868 |
Sep 19, 2016 |
10588795 |
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16799396 |
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14776642 |
Sep 14, 2015 |
9445958 |
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PCT/US14/22080 |
Mar 7, 2014 |
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15269868 |
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13827840 |
Mar 14, 2013 |
8905421 |
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14776642 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y10T 74/20834 20150115;
Y10T 74/20864 20150115; A61G 5/027 20130101; A61G 5/023 20130101;
A61G 5/026 20130101; A61G 5/024 20130101 |
International
Class: |
A61G 5/02 20060101
A61G005/02 |
Claims
1. A manual wheelchair comprising: a frame; a drive wheel connected
to the frame, having a first axis of rotation and configured to
rotate relative to the frame; a push rim connected to the frame,
having a second axis of rotation extending substantially parallel
to the first axis of rotation of the drive wheel and configured to
rotate relative to the frame, wherein the second axis of rotation
of the push rim is offset from the first axis of rotation of the
drive wheel in a direction orthogonal to the first axis of rotation
of the drive wheel; and a transmission configured to transmit
rotation of the push rim to rotation of the drive wheel.
2. The wheelchair of claim 1, further comprising a repositioning
member including a swing arm having a first end and a second end,
wherein the first end is coupled to the push rim and the second end
is coupled to the drive wheel, wherein the repositioning member is
configured to allow the push rim to be repositioned via a rotation
of the repositioning member about the first axis of rotation such
that the first end is rotated over a top of the drive wheel from a
position in front of the second end to a position behind the second
end to allow a user to transfer into and out of the wheelchair
without having to lift over the push rim.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 15/269,868 filed on 19 Sep. 2016, which is a
continuation of U.S. patent application Ser. No. 14/776,642 filed
on 14 Sep. 2015, now U.S. Pat. No. 9,445,958, which is the U.S.
National Stage of PCT/US2014/022080 filed on 7 Mar. 2014, which
claims priority to U.S. patent application Ser. No. 13/827,840
filed on 14 Mar. 2013, now U.S. Pat. No. 8,905,421, each of which
is incorporated herein by reference in its entirety as if set forth
in full.
BACKGROUND
Field of the Invention
[0002] The purpose of the invention is to provide a wheelchair
system that allows for independent positioning of the push rims and
drive wheels, allowing for improved stability and improved shoulder
biomechanics. The approach also allows for the addition of
multispeed fixed-gear hubs for improved propulsion on sloped
surfaces and allows for removal or repositioning of the push rims
out of the way for easier transfers in and out of the
wheelchair.
Related Art
[0003] The most common form of a manual wheelchair 100 utilizes a
push rim 110 connected directly to the drive wheels 120 as shown in
FIG. 1. The wheelchair user is able to propel the wheelchair 100 by
pushing the push rims 110 with their hands, thereby rotating the
wheel an equal angle and translating the chair forward. The common
wheelchair is elegant in its simplicity. However, the inherent
mechanical coupling of the push rim 110 and the wheel 120 require
that they be placed in the same fore-aft position, which may lead
to reduced stability of the wheelchair and/or shoulder problems. In
setup of the common wheelchair, the clinician must balance concerns
of shoulder biomechanics and stability of the wheelchair. On one
hand, the clinician would like to move the push rims forward to
promote a better positioning of the shoulders for propulsion. On
the other hand, the axel of the wheels 120 must remain behind the
center of gravity 130 to reduce the likelihood the wheelchair 100
will tip over backward. A common approach is to move the push
rim/wheel combination 110/120 as far forward as possible while
still maintaining a stable base 150 of support of the wheelchair by
positioning the drive wheel 120 and front casters 140 to frame the
center of gravity 130 in fore/aft directions.
[0004] The positioning of the push-rim/wheel 110/120 combination in
common wheelchairs leads to difficulties in transfers (transferring
in and out of the wheelchair 100). For example, the user must
position the wheelchair at an angle with a bed 200 or other
transfer surface in order to use a transfer board 210 (see FIG. 2).
Without a transfer board, the person must elevate their body a
significant distance to clear the wheel of the wheelchair (FIGS.
3A, 3B).
[0005] Therefore, what is needed is a system and method that
overcomes these significant problems found in the conventional
systems as described above.
SUMMARY
[0006] Described herein is a new manual wheelchair system that
decouples the push rims from the drive wheels of the wheelchair and
reconnects the push rims to the drive wheels using a belt drive or
chain drive, thus allowing for optimal stability and better
shoulder positioning for propulsion. The push rims are also
removable or rotatable for easier transfers. The wheelchair can
also include multispeed fixed-gear hubs for easier propulsion on
different terrain. The wheelchair advantageously reduces shoulder
problems that are common in persons who use manual wheelchairs
while maintaining optimal stability.
[0007] Other features and advantages of the present invention will
become more readily apparent to those of ordinary skill in the art
after reviewing the following detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The structure and operation of the present invention will be
understood from a review of the following detailed description and
the accompanying drawings in which like reference numerals refer to
like parts and in which:
[0009] FIG. 1 is a diagram illustrating an example related art
wheelchair;
[0010] FIG. 2 is a diagram illustrating an example related art
wheelchair transfer with a transfer board;
[0011] FIGS. 3A and 3B are diagrams illustrating an example related
art wheelchair transfer without a transfer board;
[0012] FIGS. 4A-4D are diagrams illustrating an example wheelchair
with a push rim capable of being rotated backward and out of the
way for transfers according to a first implementation of the
present application;
[0013] FIGS. 5A-5D are diagrams illustrating an example wheelchair
with a push rim capable of being removed and placed out of the way
for transfers according to a second implementation of the present
application;
[0014] FIG. 6 is a block diagram illustrating an example transfer
of a patient from a bed to a wheelchair according to an embodiment
of the invention.
[0015] FIGS. 7A-7B are diagrams illustrating an example wheelchair
with a push rim capable of being translated backward and out of the
way for transfers according to a third implementation of the
present application;
[0016] FIG. 8 is a diagram illustrating a user's range of motion
laid over a diagram of an example related art wheelchair;
[0017] FIG. 9 is a diagram illustrating a user's range of motion
laid over a diagram of a wheelchair according to an implementation
of the present application; and
[0018] FIGS. 10A-10C are diagrams illustrating placement of a push
rim at different positions along a wheelchair according to an
implementation of the present application.
DETAILED DESCRIPTION
[0019] Certain implementations disclosed herein provide for a
manual wheelchair that allows for optimization of stability and
shoulder biomechanics for individual wheelchair users. For example,
one apparatus disclosed herein provides a wheelchair having a drive
wheel rotatable about a first axis of rotation, a push rim
rotatable about a second axis of rotation, which is offset from the
first axis of rotation, and a transmission coupling the push rim to
the drive wheel.
[0020] Additionally, some implementations disclosed herein provide
for a manual wheelchair that allows for the positioning of the push
rim to allow transfer into and out of the wheelchair. For example,
one apparatus disclosed herein provides a wheelchair having a push
rim repositioning mechanism that allows the push rim to be rotated
between a propulsion position and a transfer position.
[0021] After reading this description it will become apparent to
one skilled in the art how to implement the invention in various
alternative embodiments and alternative applications. However,
although various embodiments of the present invention will be
described herein, it is understood that these embodiments are
presented by way of example only, and not limitation. As such, this
detailed description of various alternative embodiments should not
be construed to limit the scope or breadth of the present invention
as set forth in the appended claims.
[0022] FIGS. 4A-4D are diagrams illustrating an example wheelchair
with a push rim capable of being rotated backward and out of the
way for transfers according to a first implementation of the
present application. More specifically, FIG. 4A illustrates the
wheelchair with the push rim rotated forward into a propulsion
position. Further, FIG. 4B illustrates an enlarged view of the push
rim relocation mechanism in the propulsion position. Further, FIG.
4C illustrates the wheelchair with the push rim rotated backward
into a transfer position. Further, FIG. 4D illustrates an enlarged
view of the push rim relocation mechanism in the transfer
position.
[0023] In this implementation, the wheelchair 400 includes a frame
405, a rotatable push rim 410 connected to the frame 405 and a
drive wheel 420 connected to the frame 405. The wheelchair 400 may
also include caster wheels 440 located in front of the drive wheel
420. The caster wheels 440 and the drive wheels 420 collectively
form the base of support 435 of the wheelchair. In order to provide
a stable ride for the user, it may be preferable that caster wheels
440 and the drive wheels be positioned such that the user's center
of gravity 430 is located directly above the base of support 435,
rather than in front of or behind the base of support 435.
[0024] As shown in FIGS. 4A-4D, the axis of rotation 425 of the
drive wheel 420 is offset from the axis of rotation 415 of the push
rim. Thus, instead of being directly coupled to each other, the
push rim 410 and drive wheel 420 are connected by a transmission
460. The transmission 460 may include a drive gear/hub 450 coupled
to drive wheel 420, a push rim gear/hub 470 coupled to the push rim
410, and a chain or belt 490 connected to the drive gear/hub 450
and the push rim gear/hub 470.
[0025] Thus, de-coupling the fore-aft position of the push rims 410
and drive wheels 420 may allow a clinician to place the drive
wheels 420 in their optimal position to provide a stable base of
support 435 while still allowing the person to do "wheelies" if
needed (to go over curbs and other thresholds). Also, the position
of the push rims 410 can be set to promote the best positioning of
the wheelchair 400 user's shoulders. A potential aspect of this
more forward positioning of the push rims 410 is a reduction in
shoulder pain resulting from manual propulsion of the wheelchair.
In other words, de-coupling of the push rims 410 and drive wheels
420 may allow the clinician to place the push rims 420 in front of
the user's center of gravity 430 as shown in FIGS. 4A-4D,
potentially improving mechanical efficiency without sacrificing
wheelchair stability.
[0026] Additionally, the use of the transmission 460 with the belts
or chains 490 may allow the wheelchair to also incorporate into one
or both of the drive gear/hub 450 and the push rim gear/hub 470 a
multispeed fixed-gear hub such as the Sturmey-Archer S3X fixed-gear
hub. In such implementations, the ability to switch to higher or
lower speeds may allow the wheelchair user to go faster on smooth
even terrain and to require less torque and forces on the shoulders
to go up inclined terrain.
[0027] Additionally, in some implementations, the wheelchair 400
also includes a push rim repositioning member 480 that allows the
push rim 410 to be repositioned to allow a user to transfer into
and out of wheelchair 400 without having to lift himself over the
push rim as shown in FIGS. 3A and 3B above. In FIGS. 4A-4D, the
repositioning member 480 is a swing arm rotatably mounted to the
frame 405 and configured to rotate about the axis of rotation 425
of the drive train. As shown, the push rim gear/hub 470 and push
rim 410 are located at a first end of the swing arm 480 and the
drive wheel gear/hub 450 is located at a second end of the swing
arm 480 and the belt/chain 490 extends along the length of the
swing arm. As shown in FIGS. 4A and 4B, the swing arm 480 can be
rotated forward to position the push rim 410 forward of a user's
shoulders to allow the propulsion of the wheel chair by the user
(known as the propulsion position). As shown in FIGS. 4C and 4D,
the swing arm 480 can be rotated backward to position the push rim
410 behind a user's shoulders to allow the user to transfer into
and out of the wheelchair.
[0028] Additionally, in some embodiment, a locking mechanism 483
may be provided to releasably hold the push rim repositioning
member 480 (swing arm) in the propulsion position shown in FIGS. 4A
and 4B. Further, a second locking mechanism 487 or hard stop may
also be provided to releasably hold or limit the rearward rotation
of the push rim repositioning member 480 (swing arm) in the
transfer position shown in FIGS. 4C and 4D.
[0029] Though various aspects of this embodiment are shown in the
figures and discussed above, implementations of this application
are not limited to these aspects and alternative implementations
are discussed below.
[0030] FIGS. 5A-5D are diagrams illustrating an example wheelchair
with a push rim capable of being removed and placed out of the way
for transfers according to a second implementation of the present
application. More specifically, FIG. 5A illustrates the wheelchair
with the push rim attached to the wheelchair in a propulsion
position. Further, FIG. 5B illustrates an enlarged view of the push
rim relocation mechanism with the push rim attached in the
propulsion position. Further, FIG. 5C illustrates the wheelchair
with the push rim disconnected from the wheelchair and repositioned
for a transfer. Further, FIG. 5D illustrates an enlarged view of
the push rim removed for a transfer.
[0031] As with the implementation discussed above, in this
implementation the wheelchair 500 includes a frame 505, a rotatable
push rim 510 connected to the frame 505 and a drive wheel 520
connected to the frame 505. The wheelchair 500 may also include
caster wheels 540 located in front of the drive wheel 520. Again,
the caster wheels 540 and the drive wheels 520 collectively form
the base of support 535 of the wheelchair. In order to provide a
stable ride for the user, it may be preferable that caster wheels
540 and the drive wheels be positioned such that the user's center
of gravity 530 is located directly above the base of support 535,
rather than in front of or behind the base of support 535.
[0032] As shown in FIGS. 5A-5D, the axis of rotation 525 of the
drive wheel 520 is offset from the axis of rotation 515 of the push
rim 510. Thus, instead of being directly coupled to each other, the
push rim 510 and drive wheel 520 are connected by a transmission
560. The transmission 560 may include a drive gear/hub 550 coupled
to drive wheel 520, a push rim gear/hub 570 coupled to the push rim
510, and a chain or belt 590 connected to the drive gear/hub 550
and the push rim gear/hub 570.
[0033] Again, de-coupling the fore-aft position of the push rims
510 and drive wheels 520 may allow a clinician to place the drive
wheels 520 in their optimal position to provide a stable base of
support 535 while still allowing the person to do "wheelies" if
needed (to go over curbs and other thresholds). Also, the position
of the push rims 510 can be set to promote the best positioning of
the wheelchair 500 user's shoulders. A potential aspect of this
more forward positioning of the push rims 510 is a reduction in
shoulder pain resulting from manual propulsion of the wheelchair.
In other words, de-coupling of the push rims 510 and drive wheels
520 may allow the clinician to place the push rims 520 in front of
the user's center of gravity 530 as shown in FIGS. 5A-5D,
potentially improving mechanical efficiency without sacrificing
wheelchair stability.
[0034] Again, the use of the transmission 560 with the belts or
chains 590 may allow the wheelchair to also incorporate into either
one or both of the drive gear/hub 550 and the push rim gear/hub 570
a multi-speed fixed-gear hub such as the Sturmey-Archer S3X
fixed-gear hub, for example. In such implementations, the ability
to switch to higher or lower speeds may allow the wheelchair user
to go faster on smooth even terrain and to require less torque and
forces on the shoulders to go up inclined terrain.
[0035] Additionally, in some implementations, the wheelchair 500
also includes a push rim repositioning member 580 that allows the
push rim 510 to be repositioned to allow a user to transfer into
and out of wheelchair 500 without having to lift himself over the
push rim as shown in FIGS. 3A and 3B above. In the implementation
shown in FIGS. 5A-5D, the repositioning member 580 is release
mechanism that allows the push rim 510 to be disconnected from the
frame 505. For example, a quick release mechanism could be used to
allow the push rim 510 to be removably attached to the frame 505.
As shown in FIGS. 5A and 5B, the release mechanism (push rim
repositioning member 580) holds the push rim 510 forward of a
user's shoulders to allow propulsion of the wheelchair by the user
(known as the propulsion position). As shown in FIGS. 5C and 5D,
the release mechanism (push rim repositioning member 580) allows
the push rim 510 to be disconnected from the frame 505, and once
disconnected, the push rim 510 can be placed behind a user's
shoulders to allow the user to transfer into and out of the
wheelchair.
[0036] Though various aspects of this embodiment are shown in the
figures and discussed above, implementations of this application
are not limited to these aspects and alternative implementations
are discussed below.
[0037] FIG. 6 is a block diagram illustrating an example transfer
of a patient from a bed to a wheelchair according to an embodiment
of the invention.
[0038] By incorporating a push rim reposition member, such as shown
in the implementations of FIGS. 4A-4D and FIGS. 5A-5D, the
wheelchair 500 can now be placed directly next to the bed 600 or
other transfer surface, reducing the distance to transfer and also
reducing the height to elevate the body since the user no longer
needs to clear the wheel 520 or the push rim 510 or the
combination.
[0039] FIGS. 7A-7B are diagrams illustrating an example wheelchair
with a push rim capable of being rotated backward and out of the
way for transfers according to a third implementation of the
present application. More specifically, FIG. 7A illustrates the
wheelchair with the push rim to the wheelchair located in a
propulsion position. Further, FIG. 7B illustrates the wheelchair
with the push rim repositioned into a transfer position.
[0040] This implementation shown in FIGS. 7A and 7B may include
features and elements similar to those discussed above with respect
to the first and second implementations. Thus redundant
descriptions thereof may be omitted. As with the implementations
discussed above, in this implementation the wheelchair 700 includes
a frame 705, a rotatable push rim 710 connected to the frame 705
and a drive wheel 720 connected to the frame 705. The wheelchair
700 may also include caster wheels 740 located in front of the
drive wheel 720.
[0041] As shown in FIGS. 7A-7B, the axis of rotation 725 of the
drive wheel 720 is offset from the axis of rotation 715 of the push
rim. Thus, instead of being directly coupled to each other, the
push rim 710 and drive wheel 720 are connected by a transmission
(not specifically labeled in FIGS. 7A and 7B; individual components
labeled). The transmission may include a drive gear/hub 750 coupled
to drive wheel 720, a push rim gear/hub 770 coupled to the push rim
710, and a chain or belt 790 connected to the drive gear/hub 750
and the push rim gear/hub 770.
[0042] Again, de-coupling the fore-aft position of the push rims
710 and drive wheels 720 may allow a clinician to place the drive
wheels 720 in their optimal position to provide a stable base of
support while still allowing the person to do "wheelies" if needed
(to go over curbs and other thresholds). Also, the position of the
push rims 710 can be set to promote the best positioning of the
wheelchair 700 user's shoulders. A potential aspect of this more
forward positioning of the push rims 710 is a reduction in shoulder
pain resulting from manual propulsion of the wheelchair. In other
words, de-coupling of the push rims 710 and drive wheels 720 may
allow the clinician to place the push rims 720 in front of the
user's center of gravity as shown in FIGS. 5A-5D, potentially
improving mechanical efficiency without sacrificing wheelchair
stability.
[0043] Again, the use of the transmission with the belts or chains
790 may allow the wheelchair to also incorporate a multi-speed
fixed-gear hub to provide the ability to switch to higher or lower
speeds and thereby allow the wheelchair user to go faster on smooth
even terrain and to require less torque and forces on the shoulders
to go up inclined terrain.
[0044] Additionally, in some implementations, the wheelchair 700
also includes a push rim repositioning member 780 that allows the
push rim 710 to be repositioned to allow a user to transfer into
and out of wheelchair 700 without having to lift himself over the
push rim as shown in FIGS. 3A and 3B above. In FIGS. 7A-7B, the
repositioning member 580 is a guide rail extending along the frame
705 that the push rim 710 can be slid along. Thus, the push rim 710
may be slidingly mounted to the guide rail (push rim repositioning
mechanism 780) and repositioned at different portions along the
length of the guide rail (push rim repositioning mechanism 780). As
shown in FIGS. 7A, the push rim 710 has been slid forward along the
guide rail (push rim repositioning mechanism 780) to be located
forward of a user's shoulders to allow the propulsion of the wheel
chair by the user (known as the propulsion position). As shown in
FIGS. 7B, the push rim 710 has been slid backward along the guide
rail (push rim repositioning mechanism 780) to be located behind or
even with a user's shoulders to allow the user to transfer into and
out of the wheelchair.
[0045] Additionally, in some implementations, a locking mechanism
(not shown) may be provided to releasably hold the push rim 710
(swing arm) in the propulsion position located in front of the
user's shoulders as shown in FIG. 7A. Further, a second locking
mechanism (not shown) or hard stop may also be provided to
releasably hold or limit the rearward movement of the push rim 710
in the transfer position shown in FIG. 7B. Additionally, in some
embodiments, the transmission of the wheel chair may also include
an idler sprocket (not shown), which can be used to maintain a
fixed tension in the belt or chain 790.
[0046] Though various aspects of this embodiment are shown in the
figures and discussed above, implementations of this application
are not limited to these aspects and alternative implementations
are discussed below.
[0047] FIG. 8 illustrates the reachable workspace of a user's wrist
for different shoulder ranges of motion laid over a diagram of an
example related art wheelchair 800 and FIG. 9 illustrates the
reachable workspace of a user's wrist for different shoulder ranges
of motion laid over a diagram of a wheelchair 900 according to an
implementation of the present application. As discussed above, a
problem with conventional wheelchairs relates to the positioning of
the drive wheel/push rim assembly relative to the user's shoulders.
Rearward placement of the drive wheel/push rim assembly can improve
stability, but such placement can require a user to continually
reach backward with shoulder extension and sometimes shoulder
abduction. Use of the shoulders in excessive extension and in
abduction are thought to be damaging for repeated use. Also, some
users may have experienced reduced range of motion that can limit
the propulsive force that can be generated by the user. FIGS. 8 and
9 illustrate a hypothetical user's range of motion laid over
diagrams of a related art wheelchair 800 and a wheelchair 900
according to an implementation of the present application.
Specifically, in FIGS. 8 and 9, regions 810, 910 represent a user
with a full range of motion, regions 820, 920 represent a user with
a slightly reduced range of motion, and regions 830, 930 represent
a reduced range of motion. As shown in FIG. 8, in order to achieve
and maximize the arc of propulsion by starting the application of
torque at the upper surface of the push rim of the conventional
wheel chair, the user needs to take his shoulders into large angles
of extension (i.e. into region 810). However, by moving the push
rims forward in an implementation according to the present
application, the user may be able to apply a maximum arc of
propulsion with less shoulder extension (i.e. outside region 910,
and into regions 920, 930).
[0048] In the implementations discussed above, the push rim was
shown being movable between a propulsion position and a transfer
position. However, implementations of the present invention need
not have only two positions. Instead, a wheelchair according to the
present application may include a push rim repositioning mechanism
configured to allow customizable placement of the push rim based on
a user's specific physical dimensions and/or physical capabilities
and/or the activities that the patient is involved in. FIGS.
10A-10C illustrate placement of a push rim at various positions
along a wheelchair according to an implementation of the present
application based on a user's range of motion. FIG. 10A illustrates
the push rim 1010 of the wheelchair 1000 in position even with the
user's shoulders 1015. FIG. 10B illustrates the push rim 1010 of
the wheelchair 1000 rotated forward by 15 degrees with respect to
the user's shoulders 1015. FIG. 10C illustrates the push rim 1010
of the wheelchair 1000 rotated forward by 15 degrees with respect
to the user's shoulders 1015.
[0049] Those of skill in the art will appreciate that skilled
persons can implement the described functionality in varying ways
for particular applications, but such implementation decisions
should not be interpreted as causing a departure from the scope of
the invention. Also, in the various embodiments described above,
the improvements to the push rim and drive wheels can be implements
for a single side of the wheelchair or on both sides of the
wheelchair.
[0050] The above description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
invention. Various modifications to these embodiments will be
readily apparent to those skilled in the art, and the generic
principles described herein can be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
it is to be understood that the description and drawings presented
herein represent a presently preferred embodiment of the invention
and are therefore representative of the subject matter which is
broadly contemplated by the present invention. It is further
understood that the scope of the present invention fully
encompasses other embodiments that may become obvious to those
skilled in the art and that the scope of the present invention is
accordingly not limited.
* * * * *