Note: Descriptions are shown in the official language in which they were submitted.
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1397-6
CURB-CLIMBING POWER WHEELCHAIR
Background of the Invention--Field of the Invention
This invention relates to wheelchairs, particularly
to powered wheelchairs, for use by handicapped and disabled persons,
which can climb curbs.
Background of the Invention--Description of the Prior Art
As used herein, the term "conventional wheelchair",
including plurals and variants thereof, denotes manually powered
wheelchair apparati of the type generally disclosed in United States
patent 3,953,054.
As used herein, the terms "conventional power
wheelchair", "known power wheelchair" and "rear wheel drive power
wheelchair", including plurals and variants thereof, denote powered
wheelchair apparati of the type generally disclosed in United States
patent 4,387,325.
Power wheelchairs are known and have been the subject
of increasing development efforts to provide handicapped and disabled
persons with independent mobility to assist them in leading more
normal lives.
Power wheelchairs known heretofore resemble
conventional, manual wheelchairs: many such power wheelchairs have
merely been conventional wheelchairs equipped with motors. Use of
such power wheelchairs sometimes results in the user feeling a stigma
in that unthoughtful persons may view the power wheelchair user in a
quizzical or even offensive manner.
Known power wheelchairs tend to be large and not
particularly maneuverable. These power wheelchairs present
difficulties for the user in navigating within conventional dwellings
which have not been modified to accommodate such conventional power
wheelchairs.
Typical rear wheel drive power wheelchairs, which are
conventionally manual wheelchairs modified to be equipped with motors,
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have turning circles of about 72 inches in diameter; whereas typical
front wheel drive power wheelchairs known heretofore for the most part
have turning circles in the neighborhood of 52 inches in diameter.
These turning circles are too big for the user of a conventional power
wheelchair to reverse the wheelchair direction by turning the
wheelchair around within corridors or hallways of conventional office
buildings or most homes.
Dual drive motor power wheelchairs are known; one is
illustrated in United States patent 5,540,297. Other power
wheelchairs are disclosed in United States patents 4,513,832;
4,538,857; 5,094,310; 5,145,020 and 5,366,037.
Forward or front wheel drive power wheelchairs are
sold by Permobile, Inc. in Woburn, Massachusetts and have the driving
wheels at the extreme forward end of the vehicle chassis thereby
requiring substantial space in order to turn the power wheelchair.
This large chair turning circle results from the axis of rotation of
the chair, when turning, being at the mid-point of the drive wheel
axes, which is at the extreme forward end of the chair. Hence, the
radius of the chair turning circle cannot be substantially less than
length of the chair chassis.
A forward wheel drive power wheelchair of the type
sold by Permobile, Inc., with the drive wheels at the extreme forward
end of the wheelchair chassis, is disclosed in a brochure entitled
"Permobile Power Chair Empowering the Human Spirit" availab7_e from
that company.
Wheelchairs having relatively large diameter forward
wheels located under the central portion of the seat are known; one
such wheelchair is disclosed in U.S. patent 4,538,857.
Known power and manual wheelchairs have significant
difficulty in climbing curbs. Curbs may be six to eight inches or
even higher. Curbs of this height present very substantial, often
insurmountable obstacles for known power wheelchairs.
Summary of the Invention
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In one of its aspects, this invention provides a curb-
climbing power wheelchair including a frame, a seat preferably
removably connected to the frame, a pair of drive wheels rotatable
independently about transverse parallel axes below a portion of the
seat supporting an occupant's thighs, motors for driving respective
drive wheels with respective motor/drive wheel combinations being
pivotally connected to the frame, at least one ground engaging idler
wheel connected to the frame behind the drive wheels and anti-tip
wheels forward of the drive wheels, above the ground and rigidly
connected to the motors for pivotal movement therewith relative to the
frame .
In yet another of its aspects, this invention provides
a curb-climbing power wheelchair including a frame, a pair of drive
wheels rotatable independently about transverse parallel axes relative
to the frame, motors for rotating respective ones of the drive wheels
pivotally connected to the frame, anti-tip wheels pivotally connected
to the frame, being associated with respective ones of the drive
wheels and adjustably positionable above ground forward of an
associated drive wheel for contacting the ground upon chair forward
tipping or encountering an obstacle, and means for pivotally coupling
an associated motor and an associated anti-tip wheel for rotation
respecting said frame responsively to the motor accelerating the drive
wheel.
In still yet another of its aspects, this invention
provides a curb-climbing power wheelchair including a frame, a seat
removable from the frame without the use of tools, a pair of drive
wheels rotatable independently about transverse parallel axes below
the seat, motors for driving respective drive wheels and being
pivotally connected to the frame, electrochemical means for powering
the motors, a decorative body, anti-tip wheels positioned forward of
the drive wheels and coupled to the motors for pivotal movement
therewith respecting the frame as the wheelchair accelerates or
decelerates with the body being manually directly liftable off of the
frame in the absence of the seat without use of tools.
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Brief Description of the Drawings
Figure 1 is a perspective view looking at the right
front of a power wheelchair manifesting aspects of the invention.
Figure 2 is a side view of a power wheelchair with the
decorative body removed, illustrating certain aspects of the
invention.
Figure 3 is a rear view of the power wheelchair
illustrated in Figure 2, with the decorative body similarly removed,
illustrating certain aspects of the invention.
Figure 4 is a top view of the power wheelchair
illustrated in Figures 2 and 3, with the power wheelchair seat and
decorative body removed, illustrating certain aspects of the
invention.
Figure 5 is an exploded side view of the power
wheelchair illustrated in Figures 2 through 4 taken in the same
direction as Figure 2, illustrating the manner in which the power
wheelchair batteries, decorative body and seat are assembled with the
power wheelchair frame and running gear, and illustrating certain
aspects of the invention.
Figure 6 is a partially exploded side view of the
power wheelchair illustrated in Figures 2 through 5 taken looking in
the same direction as Figure 5, with the batteries and wheelchair body
in position and supported by the wheelchair frame and with the
wheelchair seat illustratively removed from the frame and above the
frame/body assembly, illustrating certain aspects of the invention.
Figure 7 is an isometric view of a frame for a power
wheelchair manifesting certain aspects of the invention.
Figure 8 is a view of a wheelchair seat back looking
in the same direction as Figure 3, illustrating wheelchair seat arm
width adjustment aspects of the invention.
Figure 9 is a partially broken side view taken at
arrows 9-9 in Figure 4, illustrating power wheelchair independent
drive wheel suspension which is disclosed in co-pending U.S. utility
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patent applications 08/742,972 and 08/748,214, with the drive wheel
illustrated in phantom.
Figure 10 is a partially broken side view of power
wheelchair drive wheel suspension illustrated in Figure 9,
illustrating operation of the drive wheel independent suspension upon
the drive wheel encountering an obstacle.
Figure 11 is identical to Figure 9 and is presented
for purposes of ready reference when considering Figure 12.
Figure 12 is a partially broken side view of the drive
wheel independent suspension apparatus shown in Figures 9 through 11,
illustrating aspects of operation of this suspension apparatus in
conjunction with independent anti-tip wheel suspension apparatus upon
descending down a step to a lower level.
Figure 13 is a broken side view of a seat and an upper
portion of a frame for a power wheelchair as illustrated in figures
2 through 6, including means operable responsively to manually
generated force for releasably connecting the seat to the frame,
illustrating certain aspects of the invention.
Figure 14 is a broken side view of a seat and an upper
portion of a frame for a power wheelchair, as illustrated in Figure
13, showing the seat support structure partially engaged with the
frame .
Figure 15 is a broken side view of a seat and an upper
portion of a frame similar to Figures 13 and 14, showing the
wheelchair seat mounted on the frame in a position tilted back
relative to the position illustrated in Figure 13.
Figure 16 is a broken side view of a seat and an upper
portion of a frame, similar to Figures 13 through 15, depicting the
operation of means for releasably connecting the seat to the frame.
Figure 17 is a side view taken at the position of
circle 29 in Figure 13 illustrating a latch portion of the means for
releasably connecting the seat to the frame.
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Figure 18 is a side view taken at the same position
as Figure 17 illustrating the seat subframe ready to engage a latch
portion of the means for releasably connecting the seat to the frame.
Figure 19 is a side view of the latch illustrated in
Figures 17 and 18, depicting movement of latch parts.
Figure 20 is a view of the portion of a frame and a
latch illustrated in Figures 17 and 18, taken at the same position,
illustrating vertical adjustment of a seat support member.
Figure 21 is a front elevation of the structure
illustrated in Figure 20 taken at arrows 21-21 in Figure 20.
Figure 22 is a partially broken view looking upwardly
of a portion of the seat subframe taken at arrows 22-22 in Figure 18.
Figure 23 is a partially broken side sectional view
of the structure illustrated in Figure 22.
Figure 24 is a side view of an arm of a wheelchair
seat as illustrated generally in Figures 13 through 16, showing the
manner in which the arm may be swung upwardly.
Figure 25 is an enlarged view of structure illustrated
in circle 37 in Figure 24.
Figure 26 is an enlarged view of structure illustrated
in Figure 8 taken at the position indicated by the circle marked Fig.
26 in Figure 8.
Figure 27 is a broken schematic side view of an
alternate embodiment of suspension apparatus for the power wheelchair
drive wheels and forward anti-tip wheels which is to be considered to
be taken at arrows 9-9 in Figure 4 for reference with the drive wheel
shown in phantom similarly to Figure 9, illustrating certain aspects
of the invention.
Figure 28 is a broken schematic side view of a
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels which is to
be considered to be taken at arrows 9-9 in Figure 4 for reference with
the drive wheel shown in phantom similarly to Figure 9, illustrating
certain aspects of the invention.
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Figure 29 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels similar to
Figure 28 with the drive wheel illustrated traversing a small bump.
Figure 30 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels illustrated
in Figures 28 and 29, with a drive wheel further illustrated on a curb
elevated respecting grade.
Figure 31 is a view identical to Figure 28 and is
presented for contrast with Figure 30.
Figure 32 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels illustrated
in Figures 28 through 31, with the forward anti-tip wheels shown
encountering a vertical edge of a high curb.
Figure 33 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels illustrated
in Figures 28 through 32 with the forward anti-tip wheels shown on the
top of the high curb illustrated in Figure 32.
Figure 34 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels illustrated
in Figures 28 through 33 with the drive wheels and the forward anti-
tip wheels shown on a common downgrade.
Figure 35 is a broken schematic side view of the
preferred embodiment of suspension apparatus for the curb-climbing
power wheelchair drive wheels and forward anti-tip wheels illustrated
in Figures 28 through 34 showing the drive wheels descending from a
curb with the forward anti-tip wheels contacting grade.
Figure 36 is a partially sectioned broken plan view,
taken along arrows 36-36 in Figure 28, of the preferred embodiment of
suspension apparatus for the curb-climbing power wheelchair drive
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wheels and forward anti-tip wheels shown schematically in Figures 28
through 35 formed on the side of the power wheelchair.
Figure 37 is a broken schematic side view of the
suspension apparatus for the power wheelchair drive wheels and forward
anti-tip wheels as illustrated in Figures 28 through 35, with the
drive wheel illustrated in phantom, illustrating certain structural
details.
Figure 38 is an exploded isometric view of portions
of the frame and suspension apparatus of the power wheelchair
illustrated in Figures 28 through 37.
Figure 39 is a top view of a spring pivot for securing
cylindrical spring support bases and upstanding shafts.
Figure 40 is a front view of the spring pivot shown
in Figure 39.
Figure 41 is a side view of the spring pivot shown in
Figure 40.
Figure 42 is a sectional side view of the spring pivot
and shoulder bolts, in position within the pedestal, taken along line
A-A in Figures 37 and 38, for securing cylindrical spring support
bases and upstanding shafts.
Detailed Description of the Invention
Referring to the drawings in general and to Figures
2 through 8 in particular, a curb-climbing power wheelchair
manifesting some of the aspects of the invention is illustrated
therein and is designated generally 10. Curb-climbing power
wheelchair 10 includes a frame, best illustrated in Figure 7, which
is designated generally 12 and a seat designated generally 14
supported by frame 12. Curb-climbing power wheelchair 10 further
includes a pair of drive wheels, each of which has been designated
generally 16, which are rotatably connected to frame 12 and are
rotatable about transverse axes under a central portion of seat 14.
An important aspect of this invention is the selected
geometry and configuration of the components of the curb-climbing
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power wheelchair. The inventors recognized in developing the
configuration and geometry of the curb-climbing power wheelchair the
importance of the sight and balance senses to human beings in
connection with operation of power wheelchairs. The eyes provide
vision; the otolith organs in the ears provide information regarding
balance and changes in position.
The otolith organs provide a point of reference for
humans respecting movement. Humans find movements easier to perform
and control where such movements are about axes which are aligned with
the otolith organs.
A curb-climbing power wheelchair having the axles of
the drive wheels essentially vertically aligned with the wheelchair
user's otolith organs makes the power wheelchair much, much easier for
a wheelchair user to maneuver; this is especially the case for a
disabled or handicapped wheelchair user. The less the horizontal
separation of the center of rotation of the chair and the otolith
organs in the ears, the easier it is for the user to maneuver and to
control the power wheelchair.
Ease of maneuverability is provided in the curb-
climbing power wheelchair with a seat having a cushion supporting a
wheelchair user's thighs and lower portions of the buttocks. The seat
has a back for supporting the wheelchair user's back. With seat
cushion and back portions, the wheelchair user is in a seated upright
position when using the wheelchair.
In this position the wheelchair user's otolith organs
are located above the drive wheels of the curb-climbing power
wheelchair; the axis about which the drive wheels rotate is below the
central portion of the wheelchair seat. This arrangement results in
the drive wheel axis being at substantially a longitudinally common
location with the otolith organs when the wheelchair user occupies the
wheelchair seat and sits with the user's back against the seat back.
For severely handicapped or deformed persons, custom seating may be
provided thereby to locate the severely disabled or deformed person's
otolith organs substantially at a longitudinally common location with
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the drive wheel axis when the severely disabled or deformed person
cannot sit upright.
As is apparent from the drawings, drive wheels 16 of
curb-climbing power wheelchair 10 are connected to frame 12 so that
each drive wheel 16 rotates about a transverse axis 24 which is below
a cushion portion 20 of the curb-climbing power wheelchair seat
designated generally 14, and specifically below the portion of cushion
20 which supports the curb-climbing power wheelchair occupant's
thighs. As is apparent from the drawings, drive wheels 16 are
rotatable about transverse axes which are preferably slightly forward
of the longitudinal mid-point of the wheelchair seat 14 and
specifically are rotatable about transverse axes which are preferably
slightly forward of the longitudinal mid-point of seat cushion 20.
Seat 14 is preferably mounted on frame 12 proximate
the longitudinal mid-point of frame 12. Drive wheels 16 are connected
to frame 12 and independently rotatable with respect thereto about a
transverse axis 24 which is under a central portion of frame 12
adapted to support seat 14. Drive wheels 16, which are rotatably
connected to frame 12, are rotatable about a transverse axis 24 which
is preferably under a central portion of seat 14. The axis of drive
wheels 16 is desirably between the mid-point of seat 12 and the seat
forward extremity and is most preferably closer to the mid-point of
seat 14 than to the longitudinal extremity thereof.
Cushion portion 20 of seat 14, and especially the
forward portion of cushion 20, is the portion of cushion 20 which
supports a seat occupant's thighs.
Frame 12 is illustrated isometrically in Figure 7 and
has an upper rectangular frame portion designated generally 60 which
includes left and right longitudinally extending tubular upper members
62 and forward and rear transversely extending tubular upper members
64. Members 62 and 64 are preferably welded together. As illustrated
in Figure 7, frame 12 is preferably fabricated of hollow tubular
rectangular cross-section steel members welded together.
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Frame 12 further includes a pair of forward vertically
downwardly extending members 66 which are preferably welded to and
extend downwardly from forward extremities of longitudinally extending
tubular upper members 62, as illustrated in Figure 7. A transversely
extending forward lower cross-member 68 is preferably welded to lower
extremities of downwardly extending members 66 and extends
therebetween.
Preferably welded to and extending vertically
downwardly from the center of a rear transversely extending tubular
upper member 64 is a rear vertically downwardly extending member 74
forming a portion of frame 12.
A pan 70 for carrying electrochemical means, for
powering the motors rotating drive wheels 16, in the form of one or
more batteries 32, may be welded along its forward edge to forward
transversely extending lower cross-member 68. A rear transversely
extending lower cross-member 69 is welded to the lower extremity of
rear vertically downwardly extending member 74. The rear edge of pan
70 may be welded to the forward facing surface of rear transversely
extending lower cross-member 69, which is of length equal to the width
of pan 70; rear transversely extending lower cross-member 69 is not
as long in the transverse direction as transversely extending cross-
members 64, 68. Alternatively, pan 70 may be removable from frame 12
and may merely rest at its forward and rearward edges on lower cross
members 68, 69 respectively.
Longitudinally extending tubular upper members 62
preferably have apertures 174 formed therein, preferably by drilling
or stamping. Apertures 174 receive front and rear upwardly extending
seat support members providing manual height and tilt adjustment of
the curb-climbing power wheelchair seat without use of tools. Between
apertures 174 in longitudinally extending tubular upper members 62 are
apertures 176 for mounting a spring-strut portion of drive wheel
suspension means of wheelchair 10.
Frame 12 further includes upper and lower
longitudinally extending central tubular members 178, 179
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respectively. Upper member 178 is preferably welded to and extends
rearwardly from the center of rear upper transversely extending
tubular member 64. Lower longitudinally extending central tubular
member 179 is preferably welded to, and extends rearwardly from, the
center of the rearwardly facing surface of rear transversely extending
cross-member 69, immediately below the point of welding connection
between rear vertically downwardly extending member 74 and rear
transversely extending lower cross-member 69.
Extending vertically between longitudinally extending
central upper and lower tubular members 178, 179 is outboard
vertically extending tubular member 180, which is preferably secured
to the rear extremities of longitudinally extending members 178, 179
by welding.
Frame 12 further includes a longitudinally extending
forward tubular extension member 198 which is secured to transversely
extending lower forward cross-member 68 preferably at the center
thereof, and preferably by welding.
Frame 12 may yet further include a forward upstanding
extension member 200 secured by welding to the forward extremity of
forward tubular extension member 198 and extending transversely
upwardly therefrom, as illustrated in Figure 7.
An alternative method for attaching a footrest 172 to
frame 12 is to mount the footrest to the upstanding footrest vertical
guide 200 with mechanical means such as a nut and bolt. In such case,
box-like frame 256 is first mounted on the upstanding footrest
vertical guide 200 utilizing a nut and bolt. The footrest 172 is then
bolted to box-like frame 256 for footrest 172. This allows footrest
172 to be adjustably mounted to upstanding footrest vertical guide 200
without welding the components together.
Frame 12 may yet further include a pair of eye
portions designated generally 82 in Figure 7, which may consist of a
pair of parallel plates 348 affixed to rearwardly facing surfaces of
respective vertically downwardly extending forward members 66. The
plates 348 constituting eye portions 82 include apertures 84 formed
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therein where apertures 84 are aligned in respective ones of plates
forming eye portion 82 so that each pair of plates may receive shafts
for suspension of drive wheels and associated motors and forward anti-
tip wheels from eye portions 82, as described below. Eye portions 82,
specifically the parallel plate portions thereof, are preferably
formed from single pieces of metal by bending the pieces of metal into
a U-shaped bracket where the upstanding portions of the "U" define the
longitudinally extending rearwardly facing plates 348 of eye portion
82. Such one piece, U-shaped bracket construction of eye portion 82
is visible in Figure 4.
Frame 12 may yet further include a pair of forwardly
extending pedestals 202 secured to forwardly facing surfaces of
forward vertically downwardly extending members 66, preferably by
welding. Pedestals 202 may be secured at positions on members 66
somewhat below the upper extremities thereof, as illustrated in Figure
7. Forwardly extending pedestals 202 provide points of attachment for
spring-strut combinations 44 which may be provided to moderate arcuate
movement of anti-tip wheels 42, and the drive motors which are
associated therewith, and are preferably fixedly connected thereto,
relative to frame 12. The spring-strut combinations 44 and anti-tip
wheels 42 are not illustrated in Figure 7 but are shown in Figures 2,
4 through 6 and 9 through 12; the preferred construction is
illustrated in Figures 28 through 36.
Pan 70 is preferably welded to a forward portion of
rear vertically downwardly extending member 74 as well as to a rear
portion of transversely extending lower tubular cross-member 68. The
preferably welded, box-like construction of frame 12 illustrated in
Figure 7 provides a rigid, high strength frame for curb-climbing power
wheelchair 10.
As illustrated in Figure 2, drive wheels 16 are
preferably oriented and positioned respecting frame 12 so that the
axis of rotation 24 of drive wheels 16 is between the longitudinal
mid-point 26 and forward extremity 28 of seat 14. Most desirably the
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axis of rotation 24 of drive wheels 16 is closer to the mid-point 26
of seat 14 than to the forward longitudinal extremity 28 of seat 14.
Seat 14 preferably includes a cushion portion 20 and
a back portion 22. In Figure 2 the longitudinal mid-point of seat 14,
specifically the longitudinal mid-point of seat cushion 20, is
identified as 26. The forward longitudinal extremity of seat 14 is
identified as 28 while the rear longitudinal extremity of seat 14, and
specifically seat cushion 20, is identified as 30. The axis of
rotation of drive wheel 16 is identified as 24. In Figure 2, the
longitudinal mid-point 26 of seat 14, specifically of cushion 20 of
seat 14, is indicated by both a lead line from an indicator numeral
and by a dotted vertical line. The longitudinal location of the axes
of rotation of drive wheels 16 is indicated by dotted vertical line
27 in Figure 2.
Curb-climbing power wheelchair 10 further includes at
least one battery, which has been designated generally 32, and is
carried by frame 12 (specifically by pan 70). As illustrated in
Figure 4, curb-climbing power wheelchair 10 further includes motors
76 powered by one or more batteries 32 for driving drive wheels 16;
each drive wheel 16 preferably has a drive motor 76 associated
therewith. Drive motors 76 are reversible and drive an associated
drive wheel independently. As a result, power wheelchair 10 can be
made to pivot or turn, thus able to effectively spin about a vertical
axis, by motors 76 rotating drive wheels 16 in opposite directions.
As illustrated in Figures 2 and 3, curb-climbing power
wheelchair 10 further includes a pair of idler wheels 18 which are the
rear ground engaging wheels of curb-climbing power wheelchair 10;
drive wheels 16 are the forward ground engaging wheels of curb-
climbing power wheelchair 10. Hence the curb-climbing power
wheelchair 10 of the invention is a front wheel drive curb-climbing
power wheelchair. However, many aspects of this invention are not
limited to front wheel drive or curb-climbing power wheelchairs.
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In the preferred embodiment of the invention rear
ground engaging wheels 18 are caster-type idler wheels, which are
pivotally mounted for rotation about vertical axes.
The curb-climbing power wheelchair 10, as illustrated
in the drawings, has the drive wheels 16 positioned towards the
longitudinal center 27 of the curb-climbing power wheelchair (Figure
2). This configuration concentrates, and effectively maximizes,
weight on drive wheels 16. A curb-climbing power wheelchair so
constructed in accordance with the drawings and having dimensions as
set forth herein, when carrying a 160 pound passenger, results in
about eighty-two percent (82~) of the total weight of the curb-
climbing power wheelchair and passenger being carried by drive wheels
16.
The configuration illustrated in the drawings,
positioning a large amount of total chair and passenger weight over
drive wheels 16, provides several benefits. Primarily, overall
traction is increased. With increased traction, better obstacle
climbing ability results, increasing overall capability and usability
of the curb-climbing power wheelchair. Additionally, with increased
traction, deceleration is more positive and more predictable. This
is an important safety factor in light of the fact that most, if not
all, users of curb-climbing power wheelchairs manifesting the
invention will be handicapped or disabled persons.
With increased traction also comes superior straight
line stability. The mass centralization created by the battery
placement and the user position in the curb-climbing power wheelchair
contributes to straight line stability by reducing the "pendulum
effect" present in many prior art power wheelchairs, where the user
and battery weight are effectively removed from the pivot axis of the
drive wheels.
Increased traction results in extremely accurate
response of the curb-climbing power wheelchair to inputs provided by
the wheelchair user through a joystick control. This translates into
more predictable and positive handling and a much easier learning
CA 02283355 2000-07-19
curve for the curb-climbing power wheelchair user when the user is
first becoming accustomed to the curb-climbing power wheelchair.
Yet another benefit of the geometry of the power
wheelchair is an extremely tight turning radius, resulting from the
available independent rotation of the drive wheels, in opposite
directions. This allows the user of the curb-climbing power
wheelchair to gain access to, and to turn around in, confined areas
such as those encountered in hallways, bathrooms, small kitchens and
office areas.
As illustrated in the drawings, the curb-climbing
power wheelchair has an extremely small footprint. Placement of the
drive wheels near the center of the curb-climbing power wheelchair
results in the curb-climbing power wheelchair having a turning radius
of only about nineteen and one-half inches (19 ~") in the preferred
embodiment.
As illustrated in Figures 3 and 4, idler wheels 18
located at the rear of curb-climbing power wheelchair 10 are mounted
to frame 12 and are pivotable about vertical axes identified 36 in
Figure 2. Idler wheels 18 are not powered and are desirably caster-
type wheels. Idler wheels 18 are preferably connected to frame 12
behind drive wheels 16 and, preferably, behind seat 14.
As illustrated in Figure 3, rear idler wheels 18 are
connected to a transverse beam 38 via U-shaped spindles 142 having
conventional bearing assemblies 144. With this arrangement, U-shaped
spindles 142, and hence rear idler wheels 18, are pivotable about
vertical axes 36, shown in Figure 2, upon wheelchair 10 turning and/or
one of rear idler wheels 18 encountering an obstacle such as
illustrated in Figure 3.
Rear idler wheels 18 are rotatably mounted within U-
shaped spindles 142 for rotation within the spindles about horizontal
axes 50 as illustrated in Figure 4.
As illustrated in Figure 3, transverse beam 38 is
pivotally connected to frame 12, specifically to the upper portion of
outboard vertically extending tubular rear frame member 180. The
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point of pivotal connection of transverse beam 38 to vertically
extending outboard rear frame member 180 is designated 204. Pivotal
connection of beam 38 to frame member 180 at 204 is preferably
effectuated using a conventional bearing with a pin journaled in the
bearing. As illustrated in Figure 7, member 180 preferably extends
upwardly from a lower longitudinally extending frame rear extension
member 179, which in turn extends rearwardly from a rear transversely
extending lower cross-member 69.
Pivotally mounting transverse beam 38 to vertically
extending rear frame member 180 provides a smoother ride in the event
wheelchair 10 encounters a bump. As illustrated in Figure 3, where
the right hand one of rear idler wheels 18 has been depicted
encountering an obstacle, as right hand idler wheel 18 rides over the
obstacle, beam 38 rotates about pivotal connection 204 as indicated
by double ended arrows G in Figure 3. Vertical displacement of right
hand idler wheel 18 is depicted by double ended arrow H in Figure 3;
this displacement results from idler wheel 18 encountering the
obstacle.
As illustrated in Figures 2, 3, 5, 6, 8 and 13 through
23, curb-climbing power wheelchair 10 further includes means for
releasably supporting seat 14 on frame 12 where frame 12 includes
upstanding extension portions for supporting seat 14. These
upstanding portions are designated generally 46 in Figure 5 and
include rear upstanding seat support members designated 98 and forward
upstanding seat support members 96, which are shown in Figures 2, 3
and 5.
Rear seat support members 98 extend upwardly,
preferably vertically, from frame 12 and are transversely spaced one
from another. Similarly, forward seat support members 96 extend
upwardly, preferably vertically, from frame 12 and are transversely
spaced one from another. Rear seat support members 98 preferably
include slots, which are preferably horizontally disposed and
preferably face forward seat support members 96. These slots are
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visible in Figures 5, 6, 13, 14, 15 and 16 but have not been numbered,
to enhance drawing clarity.
As best illustrated in Figures 14, 16, 17, 18, 19, 20
and 21, forward seat support members 96 preferably include hooking
members 100 (Figure 18) which are preferably pivotally mounted in U-
shaped frame portions 150 (Figure 17) of forward seat support members
96. Hooking members 100 are mounted on shafts 104 to be movable by
rotation respecting frame portion 150 of forward seat support member
96 as illustrated generally in Figure 19, where arrow A denotes
rotational movement of hooking member 100. In Figure 19, a hooking
member 100 is shown in phantom lines having rotated in the direction
of arrow A from its normal operational position illustrated in solid
lines.
Thus, hooking members 100 can rotate rearwardly, as
indicated by arrow A in Figure 19, to an orientation such that mouth
portions of the hooking members preferably move at least to a
horizontal orientation so that seat 14 may be removed from seat
support members 46, specifically from forward upstanding seat support
members 96.
Springs 102 about shafts 104 bias hooking members 100
forwardly respecting Figure 19, in a direction opposite to that
indicated by arrow A, to an orientation at which the mouth portion of
a slot in hooking member 100 faces below horizontal as illustrated in
solid lines in Figure 19. The mouth portion of hooking member 100 is
designated by arrow J in Figure 19 and is defined by an opening
between a tip 152 of hooking member 100 and a remaining surface 218
of the slot formed in hooking member 100.
As depicted schematically by double ended arrow L in
Figure 20, upstanding seat support portions 46, specifically forward
and rear upstanding seat support members 96, 98, are movable upwardly
respecting the remainder of frame 12 and specifically respecting
longitudinally extending tubular members 62 to which respective
forward and rear upstanding seat support members 96, 98 are connected.
Forward and rear seat support members 96, 98 are vertically adjustably
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CA 02283355 2000-07-19
positionable independently of one another, with respect to
longitudinally extending tubular upper member 62, thereby permitting
adjustment of height and/or tilt of seat 14 with respect to frame 12,
and specifically cushion portion 20 of seat 14.
Height adjustment of forward and/or rear upstanding
seat support members 96, 98 may be performed manually, without use of
tools. This is facilitated by forward and rear upstanding seat
support members 96, 98 residing in apertures 174 formed in tubular
members 62 as depicted generally in Figures 20 and 21. Upstanding
seat support members 96, 98 have shaft portions 154 which are
preferably cylindrical so as to preferably slidably reside in the
apertures 174 in the upper and lower portions of tubular members 62.
Preferably, a plurality of horizontal semi-circular bottomed grooves
156 are formed in each shaft 154; grooves 156 are vertically spaced
from one another and aligned at a common position on the periphery of
shaft 154, as illustrated in Figure 19.
Side walls of tubular members 62 are drilled to
slidably receive pins 158. Pins 158 are sized to fit in a selected
one of horizontal semicircular bottomed grooves 156 formed in shaft
portion 154, as illustrated generally in Figures 20 and 21. One pin
158 is provided for each of upstanding seat support members 96, 98 to
retain the same in place respecting an associated tubular member 62.
To adjust vertical position of one of seat support
members 96, 98, the associated pin 158 is removed. This is normally
accomplished by manually pulling on a pull ring 160, which is
preferably attached to pin 158 by residence in an unnumbered aperture
at one end of pin 158, as indicated generally by double ended arrow
B in Figure 21. Once pin 158 has been removed from a given horizontal
semi-circular bottomed groove 156 and is outside tubular member 62,
the associated forward or rear seat support member 96, 98 may be moved
vertically by hand, either up or down as desired; this vertical
adjustment is indicated schematically by double ended arrow L in
Figure 20.
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CA 02283355 2000-07-19
When the seat support member 96 or 98 is in the
desired position, pin 158 is replaced. This is done by pushing pin
158 through the aligned apertures in the parallel side walls of
tubular member 62, into position in the desired semi-circular bottomed
groove 156 in shaft portion 154 of the associated forward or rear seat
support member 96, 98, as depicted by double ended arrow B in Figure
21. This secures seat support member 96 or 98 in position. Seat
support member 96 or 98 is precluded from moving vertically, being
held in place respecting vertical movement by pin 158 residing within
a groove 156 formed in shaft portion 154 of an associated seat support
member 96 or 98.
Figures 20 and 21 depict interaction of a forward
upstanding seat support member 96 and pin 158 to effectuate vertical
adjustment of upstanding seat support member 96; the same structure
is provided for rear seat support members 98. Hence, front and rear
seat support members 96, 98 may be positioned vertically respecting
frame 12 independently one of another. This permits cushion portion
20 of seat 14 to be affixed to frame 12 in a level position,
accomplished by seat support members 96, 98 being at a common height
respecting longitudinally extending tubular upper member 62 in which
forward and rear seat support members 96, 98 reside.
Cushion 20 may be tilted back; this is accomplished
by having upstanding forward seat support members 96 positioned higher
respecting associated longitudinally extending tubular upper member
62 than rear upstanding seat support members 98.
Further alternatively, cushion 20 may be positioned
tilted forward by having rear upstanding seat support members 98
positioned higher respecting associated longitudinally extending
tubular upper member 62 of frame 12 than forward upstanding seat
support members 96.
Since vertical position of upstanding seat support members
96, 98 may be adjusted manually, without use of tools, an attendant
or therapist may change the seating position for the curb-climbing
power wheelchair user at the home or other premises where the curb-
CA 02283355 2000-07-19
climbing power wheelchair is used; it is not necessary to take the
curb-climbing power wheelchair to a dealer or other service facility
or to a health care facility to adjust seat height or tilt.
As shown in Figure 16, seat 14 is preferably mounted
on and may be considered to include a subframe designated generally
108 which provides a part of means for connecting seat 14,
specifically cushion 20 of seat 14, to frame 12 of curb-climbing power
wheelchair 10 so that seat 14 is releasably supported above frame 12
and may be removed from frame 12 by hand, without use of tools.
Subframe 108 preferably includes a pair of circular
cross-section longitudinally extending tubular members designated 110
affixed to the bottom of cushion 20 of seat 14. Longitudinally
extending tubular members 110 are visible in Figures 2, 3, 5, 6, 8 and
13 through 18 and are shown partially broken in Figures 22 and 23.
As shown in Figure 3, subframe 108 further preferably includes a pair
of transverse tubular members 111, longitudinally separated from one
another, extending between and secured to inwardly facing surfaces of
longitudinally extending members 110.
Seat 14, specifically cushion portion 20 of seat 14,
is secured to subframe 108 via screws passing through tubular members
111 and into the bottom of cushion portion 20 of seat 14. Tubular
members 111 are preferably separated from the lower, downwardly facing
surface of cushion 20 of seat 14 by thermoplastic washers which are
illustrated in Figure 3. Neither the screws which pass through the
thermoplastic washers to secure tubular members 111 to the bottom of
cushion portion 20 of seat 14 nor the thermoplastic washers themselves
have been numbered in Figure 3 to aid drawing clarity.
Longitudinally extending tubular members 110
preferably house pushbuttons 114 having coil springs 112 therewithin
at the forward portions thereof as illustrated in Figures 22 and 23.
Pushbutton 114 has a portion 162 which extends longitudinally
forwardly out of tubular member 110 and a longitudinally forwardly
facing end surface 166 for receiving axial manually generated force
to move pushbutton 114.
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CA 02283355 2000-07-19
Pushbutton 114 is preferably of unitary construction.
The section view illustrated in Figure 23 is a vertical section
respecting Figure 22; for this reason pushbutton 114 in Figure 23
appears to be a two part member. In fact, pushbutton 114 is
preferably a single, unitary member having an opening therein,
appearing as an open space 168 in Figure 23, which registers with slot
210 illustrated in Figure 22.
A roll pin 164 preferably extends through the walls
of tubular member 110 for limiting axial travel of pushbutton 114.
The open void 168 appearing in pushbutton 114 shown
in Figure 23, registers with slot 210 in tubular member 110 and houses
spring 112. Spring 112 is maintained in compression between roll pin
164, which extends through the wall of tubular member 110 and remains
stationary respecting pushbutton 114, and an unnumbered internal
shoulder portion of pushbutton 114 against which spring 112 abuts at
its right hand extremity viewed in Figure 23.
With spring 112 under compression, a user applying
manually generated axially oriented force to exterior surface 166
urges pushbutton 114 to the left in Figures 22 and 23. The
longitudinally extreme left end 115 of pushbutton 114, in Figure 23,
at the end opposite from surface 166, passes over forward transverse
rod 206, since there is a slight clearance provided by a relief 117
in the surface of pushbutton 114 facing rod 206 and rod 206 itself as
illustrated in Figure 23. Relief 117 permits longitudinally extreme
left end surface 115 of pushbutton 114 at the left extremity of travel
of pushbutton 114 to contact forward facing surface 216 of hooking
member 100 (Figure 19) thereby rotating hooking member 100 in the
direction indicated by arrow A in Figure 19, against the bias applied
thereto by spring 102.
When pushbutton 114 has traveled the full permissible
length of its longitudinal travel within tubular member 110, to the
left in Figure 23, and a shoulder portion 119 of pushbutton 114
contacts roll pin 164, pushbutton 114 pushes hooking member 100
sufficiently that hooking member 100 rotates into a position at which
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CA 02283355 2000-07-19
the mouth indicated by arrow J in Figure 19 is slightly open upwardly,
as illustrated by the phantom line depiction of hooking member 100 in
Figure 19, and rod 206 is no longer constrained by hooking member 100.
This permits the user to lift seat 14 vertically upwardly thereby
removing seat 14 from forward seat support member 96 without the use
of tools.
Springs 112 are under compression. When manual force
is applied to exterior button portion 166 in the axial direction
indicated generally by double ended arrow M in Figures 22 and 23,
pushbutton 114 moves to the left in Figures 22 and 23, against the
resilient force continuously applied to pushbutton 114 by spring 112.
Transverse rod 206 is fixedly retained within an
arcuate cut-out 208 formed in the bottom of longitudinally extending
tubular member 110 as illustrated in Figure 23. Rod 206 is preferably
secured to tubular member 110 by welding.
Longitudinally elongated slot 210 in the bottom of
tubular member 110, as illustrated in Figure 22, receives hooking
member 100, thus permitting mouth J of hooking member 100 to rotate
and close over rod 206 in response to the bias of spring 112.
Pushbutton 114 can traverse substantially the
longitudinal length of slot 210 under the influence of axial force
manually applied to exterior surface 162 against bias applied by
spring 112.
"Axial" force denotes force such as can be applied in
a single direction by pushing with the palm of the hand. One of the
major advantages of the curb-climbing power wheelchair is that seat
14 may be removed from frame 12 and reengaged with frame 12 solely by
application of such axial force such as may be applied using the palm
of the hand. Use of the thumb is not required. This is extremely
helpful for elderly, infirm, disabled and handicapped persons such as
those who through the effects of arthritis or other diseases, or from
injury or accident, have lost use of, or strength in, the thumb and/or
other fingers. The required axial force may be applied in a single
direction just by pushing with the palm.
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CA 02283355 2000-07-19
Axially extending tubular members 110 further include
rear transverse rods 212, illustrated in Figure 16, which are resident
within rear arcuate cut-outs similar to forward arcuate cut-outs 208
illustrated in Figure 23, but which have not been numbered in the
drawings. Rear transverse rods 212 are preferably secured to
longitudinally extending tubular members 110 by welding, similar to
forward transverse rods 206. However, at the position on
longitudinally extending tubular members 110 at which rear transverse
rods 212 are connected thereto, there is no slot analogous to axial
slot 210 illustrated in Figures 22 and 23, nor is there any spring or
pushbutton structure analogous to pushbutton 114, spring 112 and
exterior surface 162 illustrated in Figures 22 and 23.
Rear seat support members 98 are similar to forward
seat support members 96 in that rear seat support members 98 also
include an upwardly facing U-shaped frame portion similar to that of
U-shaped frame portion 150 of forward seat support members 96 (Figure
19). The U-shaped frame portion of a rear seat support member 98 is
illustrated in elevation in Figures 13 through 16. Rear seat support
members 98 include a pair of spaced-apart vertically upstanding walls,
one of which is visible in the view presented by Figures 13 through
16 and is designated 214 in the drawings.
Walls 214 are separated transversely sufficiently to
receive longitudinally extending tubular member 110 therebetween as
generally illustrated in Figures 13 through 16. Walls 214 each
preferably have parallel, transversely aligned forwardly opening
longitudinally elongated slots 210 formed therein as shown in Figure
16. The slots 210 in walls 214 of rear seat support members 98
receive rear transverse rods 212 which are affixed to lower portions
of longitudinally extending tubular members 110 closer to the rear
terminus thereof than to the forward terminus, as illustrated in
Figure 16. Hence, rear transverse rods 212 may be easily slid into
the slots in walls 214 of rear seat support members 98. Rear
transverse rods 212 are similar to forward transverse rods 206.
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CA 02283355 2000-07-19
As shown in Figure 16, rear seat support members 98
include shafts 154 which, as described above, are preferably
cylindrical in configuration, to preferably slidably reside in holes
in the upper and lower portions of tubular members 62. Rear seat
support members 98 are retained in position respecting tubular members
62 using pins 158 received in a selected one of semi-circular bottomed
grooves 156 formed in shaft portions 154, as discussed above and as
shown in the drawings (Figures 20, 21) respecting the forward seat
support members 96.
However, as illustrated in Figure 16, semi-circular
bottomed grooves 156 formed in shaft 154 of rear seat support member
98 are formed facing the rear of the curb-climbing power wheelchair;
this provides assurance that the curb-climbing power wheelchair in
general and the seat mounting system in particular is properly
assembled. If rear seat support member 98 is inserted into
longitudinally extending tubular frame member 62 backwards, with slot
210 facing towards the rear, rear seat support member 98 cannot be
secured in place because pin 158 will not be able to engage a semi-
circular bottomed groove 156 but rather will interfere with a solid
portion of shaft 154 of rear seat support member 98, as is apparent
from Figure 16.
Seat support members 96, 98 are preferably plastic
composite materials, most preferably glass filled nylon. These
materials are stronger in compression than in tension. Positioning
forward and rear seat support members 96, 98 in the manner
illustrated, with the grooves of the respective forward and rear seat
support members facing oppositely, takes advantage of the higher
compression strength characteristic of the glass filled nylon,
providing maximum strength regions in the respective seat support
members resisting stresses received when wheelchair 10 is rapidly
decelerated or accelerated,
To secure seat 14 in position on frame 12, an
individual lifts seat 12 first to position circular cross-sectioned
longitudinally extending tubular members 110 of subframe 108 between
CA 02283355 2000-07-19
the upstanding walls of rear seat support member 98 and then to
position rear transverse rods 212 in a position within forwardly
opening longitudinally elongated slots 210 as indicated generally by
arrow N in Figure 16. By initially positioning circularly cross-
sectioned longitudinally extending tubular members 110 of subframe 108
between the respective walls of rear seat support members 98, this
helps to align rear transverse rods 212 in a position to easily engage
forwardly opening longitudinally elongated axial slots 210, all as
indicated by arrow N in Figure 16. Once rear transverse rods 212
engage slots 210, rearward force is applied to seat 14, specifically
to cushion 20, to slide rear transverse rods into flush engagement
with the closed bottoms of horizontal slots 210 formed in walls 214
of rear seat support members 98.
Once rear transverse rods 212 are in this position
within slots 210, seat 14 may be pivoted downwardly about an axis
defined by rear transverse rods 212 in the direction indicated by
arrow P in Figure 14.
As seat 14 pivots about rear transverse rod 212 and
moves downwardly as indicated by arrow P in Figure 14, hooking members
100 are received within slots 210 formed in the bottoms of
longitudinally extending tubular members 110. Upwardly extending
walls 151, illustrated in Figure 21, of U-shaped frame portion 150 of
forward seat support member 96 are, similar to walls 214 of rear seat
support member 98, transversely spaced one from another sufficiently
to receive longitudinally extending tubular member 110 therebetween,
as depicted in Figure 17. Receipt of longitudinally extending tubular
members 110 between upwardly extending walls 151 of the rear seat
support members assists in alignment of the seat with the seat support
members when the seat is being engaged with the seat support members,
as described above.
As seat 14 pivots downwardly about the axis defined
by rear transverse rods 212, rods 206 encounter rounded, downwardly
sloped upwardly and forwardly facing surfaces 216 of hooking members
26
CA 02283355 2000-07-19
100. Surface 216 is so-designated and illustrated in Figures 19, 20
and 21.
As forward transverse rod 206 bears downwardly on
surface 216, the rounded configuration of rod 206 and the rounded
downwardly sloping configuration of surface 216 resolves the force
applied by rod 206 due to the weight of seat 14 to produce a force
vector on hooking member 100 which tends to rotate hooking member 100
in the direction illustrated by arrow A in Figure 19.
As hooking member rotates in the direction indicated
by Arrow A in Figure 19, tip 152 of hooking member 100 rotates into
the position illustrated in phantom lines in Figure 19 thereby opening
the mouth indicated by arrow J in Figure 19. This permits forward
transverse rod 206 to move downwardly to a position at which forward
transverse rod 206 is supported by a horizontal shoulder portion 218,
illustrated in Figure 18, of U-shaped frame 150 of forward seat member
96. This arcuate movement is indicated by arrow P in Figure 14.
Horizontal shoulder surface 218 is illustrated and so-designated in
Figures 18 and 19. Seat 14 in position, with forward transverse rods
206 resting on horizontal shoulder surfaces 218 and engaged with
forward seat support members 96, is illustrated in Figures 13 and 15.
Once forward transverse rods 206 reside on horizontal
shoulder surfaces 218, abutting forward facing shoulder surfaces 220,
illustrated in Figure 21, of forward seat support member 96 and
forward transverse rod 206 has cleared tip 152 of hooking member 100,
bias applied to hooking member 100 by spring 102 causes hooking member
100 to rotate clockwise in Figures 13 through 21 with open slot J
closing over forward transverse rod 206. Forward rod 206 is then
constrained against forward movement by hooking member 100 and against
rearward movement by forwardly facing vertical shoulder surfaces 220.
Additionally, rear transverse rod 212 is constrained against rearward
movement by the closed bottom of horizontal slot 210 in rear seat
support member 98. As a result, seat 14 is securely retained in
position, connected by vertical seat support members 96, 98 to frame
12.
27
CA 02283355 2000-07-19
To remove seat 14 from wheelchair 10, the procedure
is reversed. An individual begins by pushing exterior end surfaces
166 of pushbuttons 114 to the left, along the direction indicated by
double ended arrow M in Figures 22 and 23. This axially applied
manual force moves pushbuttons 114 to the left in Figures 22 and 23,
against the restraining force constantly applied by spring 112. As
pushbuttons 114 move to the left, end surfaces 115 of pushbuttons 116
encounter rounded forwardly and downwardly sloping surfaces 216 of
hooking members 100. Continued application of manual force to
pushbutton surfaces 166 against bias of spring 112 causes end surfaces
115 of pushbuttons 114 to push against surfaces 216 of hooking members
100, causing hooking members 100 to rotate counter-clockwise as viewed
in Figures 17 through 19, with tips 152 rotating upwardly and thereby
causing the mouth indicated by arrow J to assume a position where it
opens slightly upwardly, as illustrated in phantom lines in Figure 19.
At this position forward ends of longitudinally
extendingly tubular members 110 may be lifted since forward transverse
rods 206 are no longer restrained against vertically upward movement
by hooking members 100. Hence seat 14 may be moved upwardly in a
pivotal fashion about a pivot defined by rear transverse rods 212,
with seat 14 moving in a direction opposite that indicated by arrow
P in Figure 14. Once seat 14 has been rotated somewhat in a direction
opposite to arrow P in Figure 14, seat 14 may be moved horizontally,
to the right viewing Figure 14, thereby disengaging rear transverse
rods 212 from the horizontal forwardly facing open slots formed in
walls 214 of rear seat support members 98 and completely disengaging
seat 14 from frame 12.
As illustrated in Figure 4, curb-climbing power
wheelchair 10 preferably includes two motors for driving respective
drive wheels 16. These motors are designated generally 76 and are
each resident within a preferably rigid housing (not shown) which
houses, in addition to a motor 76, a transmission 78 for transferring
driving rotation from an output shaft of motor 76 to an associated
drive wheel 16.
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CA 02283355 2000-07-19
As illustrated in Figures 28 through 36 in the
preferred embodiment, the drive wheel/motor transmission combination
housing defines a portion of a suspension member designated generally
310 which connects with frame 12 at a pivot connection denoted 318 in
Figures 28 through 36. Hence, each drive wheel 16 is free to move
respecting frame 12 upon encountering an obstacle without the
remaining drive wheel 16 moving respecting frame 12. There is no
common axle for the two drive wheels 16.
Each drive wheel/motor/transmission combination
suspension member 310 is independently suspended respecting frame 12.
Frame 12 includes eye portions 82 which are fixedly connected,
preferably by welding, to forward vertical members 66 of frame 12 as
illustrated in Figures 7 and 28 through 36. Eye portions 82 have
apertures 84 formed therein. As illustrated in Figures 7 and 28
through 36, eye portions 82 preferably include two parallel,
transversely spaced-apart rearwardly facing longitudinally elongated
plates 348 having apertures 84 which are transversely aligned therein.
Eye portions 82 are preferably generally of U-shape configuration with
plates 348 visible in Figures 7 and 36 forming the legs of the U and
the base of the U being welded to the rearwardly facing surface of an
upstanding frame member 66.
As shown in Figure 4, transmission 78 is preferably
a right angle worm drive serving to change the axis about which
driving rotation is provided by motor 76. Specifically, motor 76 is
preferably positioned so that the motor output shaft extends generally
longitudinally. Associated transmission 78 through the right angle
worm drive provides driving rotation output via an axle, which is not
numbered in the drawings but is journaled in housing 80, drivingly
connected to a drive wheel 16.
A shift lever 79 extending out of transmission 78 may
be manually rotated to disengage transmission 78 thereby providing
free wheel operation of an associated drive wheel 16. When body 34
(Figure 1) is in place on frame 12, shift levers 79 protrude through
apertures in body 34, permitting facile switchover from driven to
29
CA 02283355 2000-07-19
freewheeling operation of an associated drive wheel 16 by the
wheelchair operator merely manually turning the associated shift lever
79.
Motor 76 and transmission 78 are preferably rigidly
connected together and are preferably maintained within a rigid
preferably one-piece motor/transmission housing 80. The cover 81 of
motor transmission housing 80 is preferably glass filled nylon, which
is extremely strong and provides extremely quite operation. Housing
80 includes an ear portion 86 extending forwardly therefrom as
illustrated in Figures 28 through 36.
Ear portions 86 preferably include apertures 88 sized
and positioned to be congruent with apertures 84 illustrated in Figure
7, so that apertures 84, 88 may be aligned. A pivot pin 90,
illustrated in Figure 36, fits within aligned apertures 84, 88 and
permits rotation of housing 80, and hence motor 76 and transmission
78 housed therewithin, relative to frame 14 responsively to
acceleration or deceleration of associated drive wheel 16.
Further preferably forming a part of the drive wheel
independent suspension apparatus is a shaft-spring combination, which
combination has been designated 95 in Figures 28 through 35. Shaft
92 of shaft-spring combination 95 is preferably pivotally affixed to
a web 170 which is preferably formed integrally as a part of the glass
filled nylon cover 81 of motor/transmission housing 80. Most
preferably two parallel webs 170 are provided as a part of glass
filled nylon cover 81 of housing 80, which webs 170 are longitudinally
commonly positioned and transversely aligned such that only a single
web 170 is visible in Figures 28 through 35; the second, remaining web
is immediately behind the visible web 170, is transversely spaced
therefrom and is a part of the same cover 81 of motor/transmission
housing 80.
Further desirably, pivotal connection of shaft 92 to
web 170 is provided by means of a transversely extending shaft, not
numbered but illustrated in Figures 28 through 35, which extends
between web 170 and the web which is hidden from view, and is
CA 02283355 2000-07-19
pivotally mounted in both of these webs for freely rotatable motion
respecting each of these webs. Shaft 92 is preferably secured to a
member which fits rotatably on the unnumbered transverse shaft
extending between web 170 and the unnumbered web hidden from view.
Shaft 92 extends preferably upwardly from connection with web 170
through an aperture formed in upper longitudinally extending member
62 of frame 14.
A coil spring 94 is wrapped around shaft 92 and at one
end preferably abuts web 170. Alternatively the lower end of spring
94 may be fixedly connected to shaft 92 or to a sleeve fitted about
the unnumbered shaft which extends transversely between web 170 and
the web which is hidden from view in Figures 28 through 35. Spring
94 at its upper end fits into a spring pivot member 380, illustrated
in Figures 38 through 42, which is rotatably retained within
longitudinally extending member 62 by a pair of shoulder bolts 382,
illustrated in Figure 42.
When a drive wheel 16 encounters an obstacle as
illustrated in Figure 29 and moves upwardly, housing 80 pivots in a
clockwise direction about pin 90. This upward pivotal movement of
housing 80 compresses spring 94 as web 170 moves upwardly thereby
reducing distance from web 170 to the lower surface of longitudinally
extending member 62. Spring 94, being compressed, exerts downward
force on web 170 and hence on housing 80. This force urges housing
80 to rotate counter-clockwise about pivot pin 90 as drive wheel 16
passes over the obstacle and moves downwardly.
When a drive wheel 16 accelerates, the drive wheel
motor/transmission combination suspension member 310 attempts to
rotate about pivot pin 90 in a counter-clockwise direction in reaction
to acceleration of the drive wheel. The counter-clockwise rotation
lifts anti-tip wheels 42 further off the ground.
Shaft 92 is preferably slidably retained within spring
pivot member 380 in longitudinally extending tubular member 62.
Sliding passage of shaft 92 through spring pivot member 380 connected
to longitudinal tubular member 62 permits shaft 92 to rise in response
31
CA 02283355 2000-07-19
to an associated drive wheel encountering an obstacle such as
illustrated in Figure 29 or to effectively rise as the
motor/transmission combination suspension member 310 rotates clockwise
about pivot point 318 in reaction to deceleration of an associated
drive wheel 16. A clearance aperture cut in the upper wall of
longitudinally extending member 62, immediately above shaft 92,
permits upward movement of shaft 92 without shaft 92 interfering with
frame 12 or with longitudinally extending member 62.
As shown in Figure 1, curb-climbing power wheelchair
further preferably includes a body 34 which not only provides a
decorative, aesthetically pleasing appearance for curb-climbing power
wheelchair 10 but also protects the wheelchair user from batteries 32
and from the electrical connections between batteries 32 and motor 76.
Body 34 further provides protection for batteries 32 and, to some
extent motors 76 and transmissions 78 within housings 80, from
liquids.
Body 34 preferably includes a central generally planar
portion 172 which, when body 34 is in place on frame 12, overlies
batteries 32 as illustrated in Figures 5 and 6 and, to a lesser
extent, in Figure 1.
As illustrated in Figures 1, 5 and 6, body 34
preferably further includes fender portions 126 which preferably
substantially wrap around upper semi-circular portions of respective
drive wheels 16. Fenders 126 preferably extend outwardly preferably
over at least major portions of the width of associated drive wheels
16, to fit closely about the drive wheel portions which are enveloped
by respective fenders 126.
Body 34 may further include a rearwardly facing
openable bonnet portion (not shown). There may be further provided
as a portion of body 34 a planar portion extending downwardly from the
openable bonnet for preferably at least substantially concealing the
rear suspension of wheelchair 10, especially transverse beam 38 from
which rear idler wheels 18 are suspended.
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CA 02283355 2000-07-19
As illustrated in Figures 1, 5 and 6 body 34
preferably further has rear corner portions 132 which are preferably
rounded and also extend over the suspension gear for rear idler wheels
18, specifically transverse beam 38 and U-shaped spindles 142.
Rounded rear corners 132 and fender portions 126 preferably transition
to central planar portion 172 via at least partially concave
transition portions 134 which have apertures for passage therethrough
of upstanding front and rear seat support members 96, 98 and
additional apertures for passage therethrough of shift levers 79 (not
shown).
As illustrated in Figure l, body 34 preferably yet
further includes, and has formed therein, a pair of forwardly facing
integral bumper members 138 lying over and protecting forward
suspension members such as spindle flanges 320 which form a part of
pivotally connected suspension member 310 which is illustrated in
Figures 28 through 37 but is not present in the version of the power
wheelchair illustrated in Figure 1, where a wishbone is used to
suspend the forward anti-tip wheel. Forwardly facing integral bumper
members 138 serve to protect suspension parts such as spindle flange
320 and associated spring-strut combinations, which resist and cushion
arcuate upward movement of forward anti-tip wheels 42 in spindle
flanges 320 relative to frame 12 as suspension member 310 pivotally
rotates about pivot connection 318. This is as illustrated in Figures
28 through 35 where the suspension and the spring-strut structure is
shown.
When the alternate suspension structure illustrated
in Figure 27 is used, the forwardly facing integral bumper members 138
lie over and protect the spring-strut-beam combinations designated
generally 44 which govern arcuate movement of forward anti-tip wheels
42 relative to frame 12.
Body 34 preferably further includes a planar portion
extending between forward bumper members 138 where such planar portion
is designated 136 and provides a kick panel for the power wheelchair
33
CA 02283355 2000-07-19
occupant. The kick panel is designated 136 and is illustrated in
Figure 1.
Body 34 preferably rests directly on frame 12. Body
34 is preferably a single molded piece of high impact plastic and is
exceedingly light. Body 34 may be manually directly lifted off of
frame 12 once seat 14 has been removed, without use of tools. Because
body 34 fits closely about frame 12 and is effectively contoured to
the shape of frame 12 and the associated members by which the rear
idler wheels 18, the forward anti-tip wheels 42 and the other
structure are connected directly or indirectly to frame 12, body 34
need not be fixed to frame 12. The power wheelchair 10 operates well
with body 34 resting on but not secured to frame 12.
Body 34 may be retained in place on frame 12 by mating
pads of respective hook and eye material (not shown), such as that
sold under the trademark Velcro, affixed to upwardly facing surfaces
of longitudinally extending tubular member 62, preferably at the
forward extremities thereof. Corresponding mating pieces of Velcro
are affixed to the undersurface of body 34 at planar portions thereof
which rest directly on the forward extremities of longitudinally
extending tubular members 62. Use of the hook and eye material
attachments minimizes any rattles which might otherwise occur as body
34 moves slightly relatively to frame 12 during operation of power
wheelchair 10.
Figure 8 illustrates structure providing means for
adjustably transversely separatingly positioning arms of seat 14 where
the arms are designated generally 182 with the left (looking forward)
arm designated 182L and the right (looking forward) arm designated
1828. The structure facilitating adjustable transverse separation and
positioning of arms 182L, 1828 includes an arm support base 184 which
is preferably a hollow rectangular cross-section tubular member. Arm
support base 184 is connected to seat 14, specifically to cushion
portion 20 thereof, indirectly.
Arm support base 184 directly connects to rearwardly
facing portions of L-shaped brackets 222, the lateral portion of one
34
CA 02283355 2000-07-19
of which is visible in Figures 13 through 16 and is partially visible
in Figure 8. The portion of L-shaped bracket 222, which faces
rearwardly and is preferably in facing contact with a rearwardly
facing surface of cushion portion 20 of seat 14, is not visible in
Figure 8; it is hidden behind the hollow rectangular cross-section
tubular member defining arm support base 184. Lateral portions of L-
shaped brackets 222 are connected to laterally facing, flange surfaces
of cushion support brackets 224 which are secured to cushion portion
20 of seat 14 and are illustrated in Figures 13 through 16.
Preferably L-shaped brackets 222 are secured to laterally facing
flange surfaces of cushion support brackets 224 via a pair of Phillips
head screws as illustrated in Figures 13 through 16 but not numbered
to aid clarity of the drawings.
Cushion support brackets 224 preferably include
upstanding flange portions, which run along the longitudinally
extending side of seat cushion 20, and bottom portions which run
longitudinally along the bottom of seat cushion 20. Cushion support
brackets 224 are preferably secured to cushion portion 20 of seat 14
via screw-type fasteners driven into the bottom of seat cushion
portion 20 through apertures in bottom longitudinally extending
portions of cushion support brackets 224.
A seat back support bracket 226 illustrated in Figure
8 and Figures 13 through 16 is of generally L-shaped transverse cross-
section and includes a rearwardly facing flange portion and a side
facing flange portion. The rearwardly facing flange portion has
apertures for screw-type fasteners to pass therethrough and into the
rearwardly facing surface of seat back 22, to secure seat back 22 to
the associated seat back support bracket 226.
Seat back support brackets 226 are preferably
connected to seat cushion support brackets 224 via a single pivot
rivet connection at each side of seat cushion 20 and seat back 22; the
single pivot rivet connection is partially visible in Figures 13
through 16. The single pivot rivet connection is partially hidden by
a portion of the arm support structure, specifically a vertically
CA 02283355 2000-07-19
extending arm support member 190 in Figures 13 through 16. The single
rivet connection between seat back support brackets 226 and seat
cushion support brackets 224 facilitates folding or pivoting movement
of seat back 22 towards seat cushion 20 about the points of single
pivot rivet connection between cushion support brackets 224 and seat
back support brackets 226.
Arm support extensions are designated generally 186
in Figure 8 and include horizontal supports 188 and vertically
extending supports 190. Arm cushions 192 are pivotally connected, as
indicated by 252 in Figures 24 and 25, to vertical supports 190 for
arcuate motion of arm cushions 192 with respect thereto.
Arm support base 184 includes a pair of tapped holes,
not illustrated in Figure 8, which receive complementary threaded
shafts (not shown) fixed to hand knobs 194, illustrated in Figure 8.
The threaded shafts affixed to knobs 194, when advanced or retracted
by rotation of knobs 194, through complemental engagement of the
threaded shafts with tapped holes in arm support base 184, move
against or retract from contact with respective horizontal arm support
portions 188 of arm support extensions designated generally 186, which
are associated with left and right arms 182L, 1828.
Frictional contact between the threaded shafts fixed
to knobs 194 and respective horizontal arm support portions 188 fixes
arm support extensions 186 in position when the threaded shafts are
tightly turned thereagainst. Fixation of arm support extensions 186
in position fixes the lateral position of arms 182L, 1828. Since
horizontal arm support portions 188 are laterally movable into and out
of arm support base 184, arms 182L, 1828 and arm cushions 192 may be
manually moved between the positions illustrated in solid lines in
Figure 8 and the positions illustrated in dotted lines in Figure 8,
thereby adjusting effective width of seat 14 of power wheelchair 10.
Knobs 194 are rotated by application of manual force
thereto. Once the knobs are turned to a position at which threaded
shafts associated therewith only lightly contact or are removed from
36
CA 02283355 2000-07-19
contact with horizontal arm support portions 188, these horizontal arm
support portions may be moved by hand, to adjust transverse separation
of arm cushions 192 and hence the effective width of seat 14, all
without use of tools.
Forward anti-tip wheels 42 do not normally contact the
ground or other reasonably smooth surface on which curb-climbing power
wheelchair 10 operates. Anti-tip wheels 42 are maintained above the
ground and provide protection against tipping in the event of forward
pitching of wheelchair 10 due to encounter with an obstacle, traverse
of a significant downgrade, and the like. The off-the-ground, anti-
tip positioning of wheels 42 is illustrated in Figures 1, 2, 5, 6, 9
through 11 and 27 through 29.
In Figures 28 through 36, a suspension member is
designated generally 310 and shown schematically. The portion of
housing 80 in which motor 76 resides, as shown in more detail in
Figure 37, forms the rear of suspension member 310 viewing Figures 28
through 36. Suspension member 310 has a central portion 314 and a
spindle flange 320 which defines the forward portion of suspension
member 310, as illustrated in Figures 28 through 36. Suspension
member 310 is connected to frame 12 at pivotal connection 318 via pin
90 passing through aperture 84 of frame eye 82.
One suspension member 310 is located on either side
of the power wheelchair 10. Each suspension member 310 houses a motor
76, which is one of the pair of motors, with one motor 76 driving each
drive wheel 16. Suspension member 310 additionally houses
transmission means 78 for transmitting torque from the associated
motor 76 to an axle of the associated drive wheel 16. The associated
drive wheel is journaled in suitable bearings within the front of
motor/transmission housing 80 which forms the central portion of
suspension member 310. The axis of rotation of the drive wheel 16 is
indicated as 24 in Figure 28.
Spindle flange 320 of suspension member 310 has a box-
like configuration with forwardly extending sides of the box being
designated 328, 330 in Figure 36. Box side 330 is the outboard side
37
CA 02283355 2000-07-19
of spindle flange 320; as a result of the illustrated geometry of
spindle flange 320 and suspension member 310, the associated anti-tip
wheel 42 is essentially longitudinally aligned with the associated
drive wheel 16 (not shown). This provides enhanced wheelchair
stability and also permits a wider footrest 172 (Figure 1).
Extending between box sides 328, 330 of spindle flange
320 is a shaft 234 (Figure 28). Mounted on each shaft 234 is a spring
support base 354, not visible in Figures 28 through 35 but shown
schematically in Figure 38. Secured to and extending upwardly from
spring support base 354 is an upstanding shaft 238, the upper
extremity of which extends through and is slidably retained within a
spring pivot 380 illustrated in Figures 38 through 42. This spring
pivot 380 resides within an aperture formed in a horizontally
extending planar portion of a forwardly extending pedestal 202 visible
in Figures 28 through 35. Pedestal 202 extends forwardly from frame
member 66. A coil spring 236 is positioned about shaft 238 between
spring support base 354 and spring pivot 380, as illustrated in
Figures 28 through 36, and as best shown in Figure 38.
Spindle flange 320 further includes a forwardly facing
anti-tip arm designated generally 331 in Figures 28 through 36 on
which a forward anti-tip wheel 42 is rotatably mounted.
Spindle flange 320 forms the forward portion of
suspension member 310 and is secured about motor/transmission housing
80 by a suitable clamp designated generally 338 in Figures 36 and 37.
Clamp 338 may be of the type conventionally used to secure mufflers
or tailpipes in automobiles and consists of a base plate 340, visible
in Figures 36 and 37, a hoop member 342 and nuts or other means for
retaining hoop member 342 to base plate 340. One such nut is
illustrated as 344 in Figure 37 engaging a threaded extremity of hoop
member 342.
The pivotal connection 318 of the suspension member
310, which is defined by motor/transmission housing 80 and spindle-
flange 320, with frame 12, is illustrated in Figures 28 through 37.
The forward portion of motor/transmission housing 80, which may be
38
CA 02283355 2000-07-19
considered the central portion 314 of suspension member 310, has a
narrowed shoulder 346 to fit between two rearwardly extending
transversely spaced apart plates designated 348 defining frame eye
portion 82 (Figure 36). Shoulder portion 346 is equipped with
suitable bearings corresponding bores or apertures are formed in
plates 348 of eye portion 82 and in outboard 334 and inboard 332
extensions of box sides 328, 330 of spindle flange 320. A suitable
pin 90 or nut and bolt combination passes through the aligned
apertures in these elements, as illustrated schematically by pivot
connection 318 in Figure 36.
In Figure 36, forward vertically downwardly extending
member 66 has been depicted in section, as has eye portion 82, to aid
the clarity of the drawing. The forward portion of motor/transmission
housing 80 has not been shaded, to aid the clarity of the drawing.
Since spindle flange 320 having forward anti-tip wheel
42 mounted thereon is fixedly connected to motor/transmission housing
80 by clamp 338, and specifically by hoop portion 342 wrapping tightly
thereabout, spindle flange 320 and motor/transmission housing 80 move
unitarily about pivotal connection 318 responsively to acceleration
and deceleration of drive wheel 16, whether due to torque applied by
motor 76 or due to wheel 16 encountering an obstacle.
Pivotal mounting of suspension member 310 to frame 12
via pivotal connection 318 at frame eye 82 facilitates operation of
the power wheelchair and particularly facilitates climbing high curbs
and descending therefrom. When the power wheelchair accelerates, as
torque generated by the drive motors is applied to the associated
drive wheels, reaction of suspension member 310 to such acceleration
causes suspension member 310 to tend to rotate about pivot connection
318 in a direction opposite that of rotation of the drive wheels 16.
For example, in considering Figure 28, acceleration of drive wheel 16
by the drive motor (not shown) causes drive wheel 16 to rotate
clockwise, driving the power wheelchair to the right in Figure 28.
This acceleration of drive wheel 16 causes suspension member 310 to
tend to rotate counterclockwise about pivot connection 318, lifting
39
CA 02283355 2000-07-19
forward anti-tip wheel 42. This rotation of suspension member 310 and
consequent lifting of anti-tip wheel 42 facilitates the climbing of
obstacles of a height which would otherwise not be surmountable by
power wheelchair 10.
When curb-climbing power wheelchair 10 descends from
a curb or other elevated area to a lower position, deceleration of
drive wheel 16 results in the tendency of suspension member 310 to
rotate in the opposite direction, namely clockwise, in drawing Figures
28 through 35. For example, considering Figure 30, as power
wheelchair 10 approaches a drop edge 322 of a path 324, the occupant
of power wheelchair 10 reduces output torque of the drive motors (not
shown) creating a load on drive wheels 16 from the associated drive
motors. This tends to decelerate the drive wheels respecting rotation
in the direction indicated by arrow AA in Figure 30. This
deceleration of drive wheels 16 causes suspension member 310 to rotate
about pivot point 84 in the direction of arrow AA in Figure 30,
causing anti-tip wheel 42 to move downwardly in Figure 30. As a
result, power wheelchair 10 desirably makes contact with lower path
326 prior to drive wheel 16 reaching edge 322 separating raised path
324 from lower path 326. This permits power wheelchair 10 to travel
over dropoffs and curbs, such as represented by edge 322, of
substantially greater height than otherwise possible.
Springs 94 and 236 are respectively compressed upon
clockwise and counterclockwise rotation of suspension member 310 in
the orientation illustrated in Figure 28. Hence, considering movement
of power wheelchair 10 to be to the right in Figure 28, as power
wheelchair 10 goes down a slight grade (such as illustrated in Figure
29) or approaches a vertical dropoff (such as illustrated in Figure
30), spring 236 urges suspension member 310 to rotate in the clockwise
direction illustrated in Figure 28 thereby urging anti-tip wheel 42
downwardly in order to contact the ground or other running surface
along which power wheelchair 10 is moving. This tendency towards
clockwise movement or rotation of suspension member 310 is resisted
by compression of spring 94. The spring constant of spring 236 is
CA 02283355 2000-07-19
preferably about one hundred ten (110) pounds per inch, while the
spring constant of spring 94 is preferably about two hundred eighty-
eight (288) pounds per inch. When power wheelchair 10 is at rest,
springs 94 and 236 are not compressed and not extended.
When power wheelchair 10 approaches an obstacle of
moderate height, such as a curb as illustrated generally in Figures
32 and 33, and when tip wheel 42 encounters the obstacle, this in
combination with acceleration of drive wheel 16 tends to cause
suspension member 310 to rotate in the counterclockwise direction as
illustrated in Figures 32 and 33. This compresses spring 236,
providing a cushioning effect.
As illustrated in Figures 2, 5 and 6, power wheelchair
may yet further preferably include a generally triangularly-shaped
skid 350 mounted on the bottom and at the rear of frame 12. Skid 350
is most preferably mounted on the bottom of and at the rear of
horizontal rear extension member 148 which is shown in Figure 4. Skid
350 is preferably nylon or another preferably polymeric material
having good lubricity characteristics. Optionally, skid 350 may be
equipped with a skid wheel 352 (Figure 2) which is preferably mounted
on a transverse axle for rotation in a direction generally parallel
with drive wheels 16 and is oriented so that the lower extremity
surface of skid wheel 352 is essentially at the same position off the
ground as the rear, lower extremity of skid 350, as depicted
schematically in Figure 2.
Skid 350 and optional skid wheel 352 serve to
facilitate the ascension of power wheelchair 10 over steep curbs of
a height such as illustrated in Figures 32 and 33. When power
wheelchair 10 ascends such a steep curb, after the drive wheel 16 has
traveled from the lower grade to the curb, and if the curb is of
sufficient height, then the curb can contact the lower portion of
frame 12, behind drive wheel 16. Skid 350 and optional skid wheel 352
prevent this and provide for sliding, non-damaging contact between the
high curb and the rear portion of the power wheelchair 10, until such
41
CA 02283355 2000-07-19
time as rear idler wheel 18 can traverse up the curb thereby
preventing hang-up of the rear castors.
A principal advantage of the power wheelchair is
provided by the spring-loaded anti-tip forward wheels 42 located in
front of each drive wheel 16. Spring-loading of wheels 42 allows
power wheelchair 10 to be driven over obstacles and over inclined
transitions without fear of drive wheel 16 lifting, thereby breaking
traction and causing stoppage of forward motion of wheelchair 10.
When attempting to climb obstacles such as ramp
transitions or small curbs, acceleration of motor 76 transmitted to
drive wheels 16 tends to cause the rear of motor 76 within housing 80
to drop; this creates an upward force on anti-tip wheels 42. This
helps anti-tip wheels 42 climb the obstacle encountered by wheelchair
10. Additionally, in situations involving ramp transition, and as the
driving surface rises and contacts the anti-tip wheels 42 thereby
applying upward force on wheels 42, downward force is created at the
center portion of suspension member 310, forcing the tires of the
drive wheels 16 into the ground, thereby further increasing traction
and the chances of the wheelchair overcoming the obstacle.
In a deceleration situation, such as when reducing
speed going down a ramp, the opposite effect is used advantageously.
As the rear of suspension member 310 rises during deceleration, this
exerts downward force on anti-tip wheels 42 which effectively
increases the anti-tip force provided by spring 236.
High maneuverability of the power wheelchair is
achieved by locating drive wheels 16 close to the longitudinal center
of the power wheelchair.
As shown, for example, in Figure 28, longitudinal
distance between the center of aperture 84 in eye 82 and the drive
axle for the associated drive wheel, where the drive axle emerges from
suspension member 310 to drive associated drive wheel 16, is
preferably in the neighborhood of from two and three quarters (2 and
3/4) to three (3) inches, measured longitudinally.
42
CA 02283355 2000-07-19
Longitudinal distance between pivotal connection 318
and shaft 234 defining the point of application of downward bias of
spring 236 to suspension member 310 is preferably about 5 and 63/100
inches. This pivotal connection of suspension member 310 to frame 12
via eye 82 provides the active independent suspension system for the
combination of suspension member 310, anti-tip wheel 42 and associated
drive wheel 16.
In Figure 35, depicting a power wheelchair descending
from a curb, at the position illustrated both springs 94 and 236 exert
downward bias on suspension member 310 thereby cushioning the power
wheelchair just as drive wheel 16 contacts the lower level. Spring
94 is compressed due to deceleration of drive wheel 16 and the
resultant tendency of suspension member 310 to rotate clockwise, as
in Figure 35; spring 236 is compressed as a result of anti-tip wheel
42 contacting the lower level before drive wheel 16.
As shown in Figure 35, distance between the point of
attachment of shaft 92 with suspension member 310 and drive wheel axis
of rotation 24 is substantially less than distance between the point
of attachment of shaft 234 to spindle portion 320 and pivotal
connection 318 of suspension member 310 with frame eye 82. In
situations such as depicted in Figure 35, spring 236 urges suspension
member 310 to rotate in a clockwise direction (as viewed in Figure
35), causing anti-tip wheel 42 to drop towards the lower surface,
minimizing forward tip of the power wheelchair when descending curbs.
In the embodiment illustrated in Figure 27, anti-tip
idler wheels 42 are connected directly to frame 12 via U-shaped
spindles 228; one leg (of the U-shape) of one of spindles 228 is shown
in side view in Figure 27. The U-shape of spindles 228 is readily
apparent from Figure 4.
U-shaped spindles 228 are preferably fabricated by
welding rectangular cross-section tubular stock between two parallel
plates with the tubular stock forming the base of the U. Spindles 228
are pivotally connected directly to downwardly extending members 66
of frame 12, preferably using screw-bolt assemblies. The side plate
43
CA 02283355 2000-07-19
portions of spindles 228 fit pivotally on either side about the lower
portions of respective downwardly extending vertical tubular members
66, which are illustrated in Figure 7. Nut and bolt pivotal
connections of U-shaped spindles 228 to vertically downwardly
extending members 66 are depicted schematically by indicator numeral
230 in Figure 27.
Extending upwardly between the legs of U-shaped spindles
228 are shafts (not shown) about which springs 236 reside. These
shafts are mounted on spring support bases 354, in the same manner as
illustrated in Figure 38. The upper extremities of the shafts extend
through and are slidably retained within spring pivots 380, in the
same manner as illustrated in Figure 38, residing in horizontally
extending planar portions of forwardly extending pedestals 202, which
are visible in Figure 7 as well as in Figure 27.
With this arrangement, upon an anti-tip wheel 42
encountering an obstacle or upon wheelchair 10 pitching forwardly,
anti-tip wheels 42 move arcuately, together with U-shaped spindle 228,
as they pivot about pivotal connection 230 relative to frame 12. As
the illustrated anti-tip wheel 42 and U-shaped spindle 228 pivot about
connection point 230, upward movement of spindle 228 causes distance
between shaft 234 and pedestal 202 to decrease, thereby compressing
spring 236, as illustrated in Figure 27.
As shown in Figures 39 through 42, spring pivot 380
has a head portion 388 and a tapered sleeve portion 390 that are
rigidly connected. As shown in Figures 37 and 38, an upstanding shaft
238, which is secured to and extends from the cylindrical spring
support base 354, fits inside tapered sleeve portion 390 (not shown
in Figures 37 and 38) of the spring pivot 380.
As shown in Figure 42, upstanding shaft 238, spring
236, and spring pivot 380 are held together by shoulder bolts 382
which pass through apertures 384 in the relevant frame member and
threaded apertures 386 in the head of spring pivot 380. Shoulder
bolts 382 allow the spring 236 and upstanding shaft 238 to pivot on
44
CA 02283355 2000-07-19
the shoulder bolts 382 of the spring pivot 380 when the spring 236 is
compressed.
In the embodiment illustrated in Figure 27, as the
anti-tip wheels 42 encounter an obstacle, spring 236 is compressed
upward and the upstanding shaft 288 (not shown) pivots on spring pivot
380 mounted to pedestal 202 of frame 12. Therefore, spring pivot 380
allows upstanding shaft 238 and spring 236 to pivot on shoulder bolts
382 as spring 236 is compressed when anti-tip wheels 42 of the power
wheelchair contact an obstacle on the ground.
Compression of spring 236 provides a cushioning effect
when anti-tip wheels 42 contact an obstacle or contact the ground due
to forward pitching of curb-climbing power wheelchair 10. The
suspension of anti-tip wheels 42 provided by spindle 228, connects
anti-tip idler wheels 42 to frame 16 for arcuate upward motion
relative to frame 12 upon forward tipping of power wheelchair 10 or
contact of anti-tip wheels 42 with an above-grade obstacle, as
illustrated in Figure 33.
As shown in Figure 27, a nut 240 mounted on a threaded
portion of the shaft extending above pedestal 202 permits selectable
compression of spring 236 thereby providing adjustment of the spring
force applied to anti-tip wheels 42 to resist arcuate upward movement
thereof upon forward tipping of power wheelchair 10 or upon wheels 42
encountering an obstacle. Rotation of nut 240 also adjusts the
distance at which wheels 42 are from the ground.
In this embodiment illustrated in Figure 27, longitudinal
distance between pivot 90 defined by the position of aperture 88 in
ear 86 of housing 80 and the drive axle (not shown) for the associated
drive wheel 16, where the axle emerges from housing 80 to drive
associated drive wheel 16, is preferably in the neighborhood of from
two and three quarters (2 and 3/4) to three (3) inches, measured
longitudinally. This pivotal connection of the drive
motor/transmission housing 80 to frame 12 via pivotal connection 90
of ear portion 86 with eye portion 82 provides active independent
CA 02283355 2000-07-19
suspension for the combination of motor 76 and transmission 78 in
housing 80, and associated drive wheel 16.
Movement of motor 76 and especially pivotal movement
of housing 80 relative to frame 12 indirectly controls action of anti-
tip wheels 42 in the embodiment illustrated schematically in Figure
27. A pivoting beam 270 is pivotally connected to forward vertically
extending member 66 of frame 12 via a pivotal connection denoted 276
in Figure 27. At a forward end of pivoting beam 270 a vertical link
268 is pivotally connected thereto at a pivot connection denoted 278.
The lower end of vertical link 268 is pivotally connected to spindle
238 via a pivotal connection which has not been numbered in Figure 27.
At the opposite, rearward end of pivoting beam 270,
an intermediate link 274 is pivotally connected thereto via a
connection denoted 280 in Figure 27. At the remaining end of
intermediate link 274 there is pivotal connection 282 effectuating
connection of intermediate link 274 and motor link 272, which is
preferably fixedly connected to housing 80 of motor 76 and
transmission 78. The linkage consisting of pivoting beam 270,
vertical link 268 and intermediate line 274 transfer motion between
the rear end of motor/transmission housing 80 remote from pivot point
90 and forward anti-tip wheels 42, thereby accomplishing indirectly
the same action/reaction of these components to drive wheel
acceleration/deceleration as accomplished by the direct connection
structure illustrated in Figures 28 through 37.
With tilt of seat 14 being adjustable in a manner that
cushion portion 20 of seat 14 may be level or positioned tilted
forward or tilted back, it is desirable to provide adjustment for arm
cushion portions 192 of seat 14 so that arm portions 192 may be
adjustably positioned, desirably in a level orientation regardless of
whether cushion portion 20 of seat 14 is level, tilted forward or
tilted back. Structure facilitating adjustment of the position of arm
portion 192 and permitting arm portion 192 always to be positioned in
a level orientation is illustrated in Figure 24.
46
CA 02283355 2000-07-19
Each arm, generally denoted 182, includes an arm
cushion portion 192 which is preferably upholstered to provide
cushioning for the arm of the user of power wheelchair 10. Arm
cushion portion 192 is mounted on a longitudinally elongated support
web 244. Arm cushion portion 192 and longitudinally elongated support
web 244 together constitute arm 182 of curb-climbing power wheelchair
10.
Support web 244 has a horizontally oriented central
portion 246, on which arm cushion portion 242 is supported, and two
vertically extending webs 246 (unlabeled), which are visible in Figure
8. Webs 246 may be of different size and shape with one of webs 246
supporting joystick controller 196 and electronics associated
therewith and the remaining web 246 being of more tapered, somewhat
truncated shape. Web 246 supporting joystick 196 and the associated
electronics is denoted 246J in the drawings (Figure 24).
Affixed to the lower longitudinal extremity,
preferably by welding, of a vertical support portion 190 of arm
support extension 186 (Figure 8) is a mounting block 248, as
illustrated in Figures 24 and 25. Mounting block 248 preferably has
a tapped hole (not shown) therein. Residing within the tapped hole
is a bolt 250 threadedly engaging the tapped hole. Bolt 250 can be
advanced into or withdrawn from the tapped hole in mounting block 248
to vary length of bolt 250 protruding from mounting block 248.
Arm 192 connects to vertical support portion 190 via
a pivotal connection provided by a rivet indicated as 252 in Figures
24 and 25.
As shown in Figures 24 and 25, vertical webs 246, 246J
of longitudinally elongated support web 244 are spaced apart to
receive the extremity of arm vertical support portion 190
therebetween. Mounting block 248 is preferably of the same width,
measured transversely to the plane of the paper, as the interior of
vertical arm support portion 190; mounting block 248 and bolt 250 fit
easily slidably between webs 246, 246J of arm 182.
47
CA 02283355 2000-07-19
When arm 182 is pivoted downwardly about the pivotal
connection provided by rivet 252, in the direction indicated by the
double ended arrow in Figure 24, the central portion of longitudinally
elongated support web 244 contacts the head of bolt 250; support web
244 cannot move further arcuately downwardly as a result. Adjustment
of the position of bolt 250, by rotating bolt 250 and advancing bolt
250 into or out of mounting block 248, adjusts the angle at which arm
182 (and specifically the central portion of longitudinally elongated
support web 244) contacts bolt 250. This facilitates the adjustment
of the angular position of arm 182 relative to the remainder of seat
14 when arm 182 is positioned at the limit of its arcuate downward
travel.
Footrest 172 (Figure 1) is adjustable to accommodate
users of the curb-climbing power wheelchair of various heights.
Additionally, the angle of footrest 172 is adjustable to provide
maximum foot comfort for the user of the power wheelchair.
Footrest 172 is mounted for adjustable vertical
movement along upstanding extension member 200 illustrated in Figure
7. Member 200 preferably has vertically elongated slots formed in its
forwardly and rearwardly facing surfaces; only the slot in the forward
facing surface of member 200 is visible in Figure 7.
Mounted in the opening at the top of upstanding
extension member 200 is a knob and threaded shaft combination 253.
The knob, which is designated 254 and is at the extreme upper portion
of the attached threaded shaft is visible in Figures 1 and 2. The
threaded shaft portion (not shown) preferably runs down the length of
the interior of upstanding extension member 200. The knob/threaded
shaft combination 253 is retained in place by a square bushing which
preferably fits flushly within the upper opening of upstanding
extension member 200, which opening is visible in Figure 7. The
bushing is not shown in the drawings.
Footrest 172 is connected to upstanding extension
member 200 by an open, box-like frame 256 shown in Figure 7. Frame
256 fits slidably about upstanding extension member 200, in
48
CA 02283355 2000-07-19
essentially complemental-facing contact with the four exterior
surfaces of upstanding extension member 200. A transversely extending
pivot pin 257, visible in Figure l, provides pivotal connection
between footrest 172 and open box-like frame 256, permitting footrest
172 to tilt upwardly by pivotal motion about the pivot pin respecting
open box-like frame 256 and upstanding extension member 200.
A nut (not shown), preferably a ball nut, threadedly
engages the threaded shaft portion of the knob/threaded shaft
combination 253 and is resident within vertically upstanding extension
member 200. A pair of threaded shafts extend through apertures in the
forwardly and rearwardly facing walls of open box-like frame 256 and
through the vertically elongated slots in the forward and rearwardly
facing surfaces of vertically upstanding member 200 and engage the nut
within upstanding member 200. This pair of threaded shafts restrain
the nut from rotating with the threaded shaft of the knob/shaft
combination 253 upon rotation of the knob 254.
With this arrangement, rotation of knob 254 produces
corresponding rotation of the attached threaded shaft (not shown)
since the knob 254 and threaded shaft are fixedly connected. Since
the interior nut threadedly engages the threaded shaft, if the nut
were not restrained against rotation, the nut would rotate with the
shaft. However the threaded shafts restrain the interior nut against
rotation and hence cause the interior nut to rise or fall according
to the direction of rotation of the shaft and knob 254. This rise and
fall of the interior nut carries the associated threaded shafts and
hence open box-like frame 256 and footrest 172 therewith, as the knob
254 is rotated clockwise or counter-clockwise. Hence, vertical
position of footrest 172 can be adjusted along the length of the
vertically elongated slots present in vertically upstanding member 200
by manually turning knob 254; no tools are required for adjusting
vertical position of footrest 172.
Angular orientation of footrest 172 relative tc
vertically upstanding member 200 may also be adjusted.
49
CA 02283355 2000-07-19
Footrest 172 includes an upstanding lip, visible in
Figure 1 and designated generally 264. An aperture 265 through the
rear portion of lip 264, located at the transverse mid-point thereof,
is tapped. A correspondingly threaded shaft (not shown) is provided
for complemental threaded engagement with the tapped aperture 265 in
lip 264. The threaded shaft, which has a knob attached thereto
designated generally 266, abuttingly contacts the forward facing
portion of a plate-like downward extension portion of open box-like
frame 256. This forwardly facing downward plate-like extension covers
the vertically elongated slot in the forwardly facing surface of
vertically extending member 200 and provides a place for abutment of
the threaded shaft. By rotating a hub (not shown) attached to the
threaded shaft, thereby advancing or retracting the threaded shaft
relative to lip 264, a greater or lesser portion of the shaft extends
from the rear of lip 264 to contact the downward plate-like extension
of the forwardly facing portion of open box-like frame 256. This
provides adjustment of angular position of footrest 172.
Preferably, cushion portion 20 of seat 14 is about 17
inches wide. Back portion 22 of seat 14 is preferably about 16 inches
high in the seat style illustrated in Figures 2 through 6. In the
style illustrated in Figure 1, back portion 22 of seat 14 is about 18
inches high.
In the seat style illustrated in Figures 2 through 6,
the longitudinal length of cushion portion 20 of seat 14 is preferably
between 16 and 18 inches, most preferably 16 inches.
The use of seat height adjustment means provided by
forward and rear upstanding seat support members 96, 98 permits
adjustment of the height of seat 14 from about 16 and one-half inches
to about 18 and one-half inches, measured from the bottom of seat 14
to the surface on which power wheelchair 10 rests.
Drive wheels 16 are preferably fourteen inch (14") or
sixteen inch (16") diameter drive wheels. Rear idler wheels 18 are
preferably eight inches (8") or ten inches (10") in diameter wheels.
CA 02283355 2000-07-19
Forward anti-tip wheels 42, are preferably six inches (6") or eight
inches (8") in diameter.
Power wheelchair 10 preferably has an overall length
of thirty-nine and one-half inches (39 ~") and a width of twenty-five
and four-tenths inch (25 4/10"). This results in the vehicle having
a turning radius of nineteen and one-half inches (19 ~"), permitting
power wheelchair 10 to be used easily in indoor environments, that
have not been modified to accommodate handicapped personnel and
conventional wheelchairs.
Power wheelchair control is effectuated utilizing a
joystick controller designated generally 196 in the drawings.
Suitable joystick controllers are available from *Penny & Giles in
Cristchurch, England, and are programmable and adjustable to provide
variable sensitivity for the user.
The geometry provided by the arrangement of the frame
12, seat 14, drive motors 76, drive wheels 16, idler wheels 18 and
anti-tilt wheels 42 provides outstanding handling and control as a
result of weight distribution of the power wheel chair being very low.
A power wheel chair with body 34 in place on frame 12,
has a center of gravity, when empty, about one and nine-tenths inches
(1 and 9/10") above the axis of rotation 24 (Figure 2) of drive wheels
16. Further, the center of gravity of the wheelchair 10 when empty
is about 3.1 inches behind the axis of rotation 24 of drive wheels 16.
With the aforementioned dimensions, and when wheelchair 10 is empty,
the center of gravity of wheelchair 10 is about 15.2% of the
longitudinal distance between the axis 24 of drive wheels 16 and rear
idler wheels 18.
*TM
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