Note: Descriptions are shown in the official language in which they were submitted.
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- HELICAL DRIVE WHEELCHAIR
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to wheelchairs.
Description of the Related Art
In a conventional non-motorized wheelchair, when powered by the user, the user
must
grab a large wheel or a hand rail disposed around the large wheel and push in
a forward direction
for forward movement. To move straight ahead, the user must simultaneously
push the tu~o large
wheels, one on either side of the user. To cause the wheelchair to turn right,
the user must push
only on the large wheel or associated hand rail on a left side of the chair.
To ma>;e a left turn,
the user must push only on the wheel or associated hand rail on the right side
of the wheelchair.
The motion of pushing the chair requires a certain level of manual dexterity
and upper
body strength not found in all wheelchair users. Those wheelchair users who
lack the required
manual dexterity and upper body strength must either have someone push their
wheelchair or they
must use a more expensive motorized wheelchair. Any speeds, except for very
slow speeds. are
1 S awkward to obtain.
SUMMARY OF THE INVENTION
The present invention addresses the above problems in the related art and has
as its object
to provide a wheel chair which can be operated by wheelchair users having less
upper body
strength and manual dexterity than is required to operate a conventional non-
motorized
wheelchair.
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It is further an object of the invention to provide add-an component parts for
converting
a conventional non-motorized wheelchair to one which requires less upper body
strength and
manual dexterity to operate than a conventional non-motorized wheelchair.
A first embodiment of the invention is a wheel chair having two large wheels.
One large
wheel is disposed on the left side of the wheelchair and another large wheel
is disposed on the
right side of the wheel chair. Both large wheels are disposed toward a front
portion of the
wheelchair. A single smaller pivoting wheel is disposed in a central position
of a rear portion
of the wheelchair. A helical drive is associated with each of the two large
wheels. Each helical
drive is powered by a rectilinear motion. Such a motion requires less manual
dexterity and upper
body strength than that which is required to power a non-motorized
conventional wheelchair.
A second embodiment is identical to the first embodiment, but instead has two
smaller
wheels disposed at a rear portion of the wheelchair, one on the left and
another on the right.
This embodiment has the same advantages as the first embodiment.
A third embodiment has four wheels of equal size. The two front wheels are
powered by
two parallel mounted helical drives.
A fourth embodiment provides two helical drives for powering the two Large
rear wheels
of a wheelchair. The two front wheels are small and are not powered.
A helical drive is provided which includes a helical member which is a twisted
flat bar
and a slider. The slider has an opening having the twisted flat bar disposed
therethrough. A
sliding motion of the slider causes the twisted flat bar to rotate.
Two helical drives for powering the wheelchair are on each wheelchair. Each
helical
drive includes a pinion gear which engages a crown gear. The crown gears are
fixed to the drive
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wheels of the wheelchair, such that rotation of each of the crown gears causes
rotation of the
respective wheel.
Add-on components for converting a conventional wheelchair to one which is
powered
by a helical drive are provided, thereby gaining the advantages described in
the embodiments
described above.
Other objects and features of the invention will appear in the course of the
description
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a top plan view of a first embodiment of a helical drive wheelchair
having a
single small pivoting wheel disposed in a rear portion of the wheelchair.
Fig. 2 is a side plan view of the wheel chair shown in Fig. 1.
Fig. 3 is a top plan view of a second embodiment of the helical drive
wheelchair having
two small pivoting wheels disposed in a rear portion of the wheelchair.
Fig. 4 is a side plan view of the wheelchair shown in Fig. 3.
1 S Fig. 5 is a top plan view of a third embodiment of a wheelchair having
four wheels of
equal size.
Fig. 6 is a side plan view of the wheelchair shown in Fig. 5.
Fig. 7 is a top plan view of a fourth embodiment of a wheelchair having two
large wheels
driven by helical drives and two small front wheels.
Fig. 8 is a side plan view of the wheelchair shown in Fig. 7.
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Fig. 9 is a side plan view of the components of an embodiment of a helical
drive, as used
in Ftgs. 1, 2, 3, 4, 7, and 8.
Fig. 10 is a top plan view of an embodiment of two helical drives including a
synchronizing gear and a single crown gear having an axle disposed
therethrough, as used in Fig.
S 5 and Fig. 6v
Fig. 11 is a top plan view of two helical drives including a separate crown
gear being
engaged by a pinion gear of each helical drive, as used in Figs. l, 2, 3, 4,
7, and 8.
Fig. 12 shows another embodiment.
Figs. 13-16 show other helical drive configurations.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 and 2 show a first embodiment of the present invention, a helical drive
wheelchair.
As shown in the figures, two large wheels 10 are each attached to ends of
their respective axles
such that the two large wheels 10 protrude from a right and left side of a
wheelchair frame 20
close to the front of the wheelchair. A single small pivoting wheel 25 is
mounted in a central
position of the rear of the wheel chair.
A helical drive is disposed on the right and left sides of the wheel chair.
Each helical
drive 30 is attached to the frame 20 via a rod 40 extending outward from the
frame 20 on the
left and right sides of the wheelchair, such that each helical drive 30 is
disposed on an outer side
of a corresponding large wheel 10. An annular crown gear 50 protrudes
outwardly from a hub
of each large wheel 10. The hub is fixedly attached to elongated sections or
spokes 52 which
extend from the hub to the annular rim of the wheel 10. Each helical drive 30
has a pinion gear
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55 'protruding from an end of the helical drive. The pinion gear 55 is
disposed in contact with
the crown gear 50, such that rotation of the pinion gear 55 causes the crown
gear to rotate,
thereby rotating the large wheel. The helical drive 30 has an input device
including a handle 60.
Sliding the handle 60 along a slot formed in an outer casing 70 of the helical
drive 30 in one
direction causes a helical member within the outer casing 70 to rotate,
thereby causing the pinion
gear 55 to rotate. Moving the handle 60 in the other direction causes the
helical drive to free
wheel and resets the handle 60.
Figs. 3 and 4 show a second embodiment of the present invention. As shown in
the
figures, two large wheels 10 are each attached to ends of their respective
axles such that the two
large wheels 10 protrude from a right and left side of a wheelchair frame 120
close to the front
of the wheelchair. Two small pivoting wheels 125 are mounted on left rear and
right rear
portions of the frame 120. Two helical drives 30 are disposed on the right and
left sides of the
wheel chair. Each helical drive 30 is attached to the frame 120 via a rod 140
extending outward
from the frame 120 on the left and right sides of the wheelchair, such that
each helical drive 30
1 S is disposed on an inner side of a corresponding large wheel 10. An annular
crown gear 150
protrudes inwardly from a hub portion of each large wheel 10. Each helical
drive has a pinion
gear 55 protruding from an end of the helical drive. The pinion gear 55 is
disposed in contact
with the crown gear 150, such that rotation of the pinion gear 55 causes the
wheel driving gear
to rotate, thereby rotating the large wheel 10. The helical drive 30 has an
input device including
a handle 60. Sliding the handle 60 in one direction along a slot formed in an
outer casing 70 of
the helical drive 30 causes a helical member within the outer casing 70 to
rotate, thereby causing
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the pinion gear 55 to rotate. Moving the handle 60 in the other direction
causes the helical drive
to free wheel and resets the handle 60.
The first two embodiments show a wheelchair having large wheels disposed
toward the
front of the wheelchair. However, the large wheels could be disposed toward
the rear of the
wheelchair and pivoting small wheels disposed toward the front of the
wheelchair, as in Figs. 7
and 8.
The embodiments in Figs. 1, 2, 3, 4, 7, and 8, show helical drives directly
connected to
the drive wheels, and oriented radial to the wheels. However, other
orientations are possible,
with a linkage connecting the pinion gear of the helical drive with the crown
gear on the wheel.
The linkage could be, for example, a belt drive, a chain drive, or a drive
shaft. For example, the
helical drive may bo horizontal, parallel to the ground, with a drive shaft
connecting the pinion
gear on the helical drive to the crown gear on the drive wheel. See for
example, in Fig. 12, drive
wheel 1201, and front wheel 1202 are attached to the frame 1203. Helical drive
1204, with
handle 1205 and pinion gear 1206, drives wheel 1201, through drive shaft 1207.
Shaft 1207
connects pinion gear 1206 to annular crown gear 1208 fixed to wheel 1201. This
drive shaft
arrangement can also be used in the front wheel drive wheelchair in Fig. 1 and
2. The helical
drive can be installed at any angle.
Figs. 5 and 6 show the next embodiment of the helical drive wheelchair. This
embodiment comprises four wheels 200 of approximately the same size. Each
wheel has a hub
202 fixedly attached to an end of an axle 204 or 202. Each hub 202 is disposed
in the center of
an area defined by an annular rim of the wheel 200. The hub is fixedly
attached to elongated
sections or spokes 206 which extend from the hub to the annular rim of the
wheel 200. The front
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axle 204 is received in an opening formed in two axle receiving sections 208
which are aligned
such'that the axle 204 passes through the opening formed in both axle
receiving sections 208.
An annular crown gear 210 is disposed on a portion of the axle 204 such that
the axle 204 is
fixedly attached to and disposed through the center of the crown gear. Two
parallel helical drives
212, each having a slidable disposed handle 214, are disposed such that a
pinion gear 216
extending from an end of each helical drive 212 engages the crown gear 210.
The two helical
drives 212 include a connecting section 217 which extends between the two
helical drives 212
and integrally connects the helical drives 212. A frame 218 extends from the
axle receiving
sections 208 toward the rear of the wheelchair. The rear of the frame 218
includes an opening
forming a rear axle receiving section (not shown) through which the rear axle
202 passes. Like
the front wheels 200, a hub of each of the rear wheels 200 is attached to an
end of the rear axle
202. A seat 220 is disposed over a rear section of the frame 218 extending to
the rear wheels
200. A seat back 222 extends upward from an end of the seat 220 closest to the
rear of the
wheelchair such that the seat back 222 forms an angle with the seat 220 which
is more than 90
IS degrees.
A seated user of the wheelchair operates the wheelchair by sliding the handles
214 of the
helical drives 212. The sliding motion causes a helical member in each helical
drive to rotate.
When viewed from a perspective of a person seated in the wheelchair, the right
helical drive 212
causes the corresponding pinion gear 216 to rotate in a clockwise direction
and the left helical
drive 212 causes the corresponding pinion gear 216 to rotate in a
counterclockwise direction.
The pinion gears 216 engage the crown gear 210 thereby forcing the crown gear
210 to rotate
in a forward direction.
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Figs. 7 and 8 show the next embodiment of the wheelchair. This embodiment
includes
two jarge wheels 224 disposed toward the rear of the wheel chair and two small
wheels 226
disposed toward the front of the wheel chair. Each of the wheels has a hub 202
and spokes 206.
Each hub is attached to an axle. The front axle is disposed through openings
formed in the
S frame. Extending outward from the hub of each of the rear wheels 202 is a
crown gear 228. A
pinion gear 216 extending from an end of the helical drive 212 is engages the
crown gear 228
such that when the pinion gear 216 rotates, the crown gear 228 rotates.
Figs. 7 and 8 show the helical drives 212 and crown gears 228 being disposed
on an
outside portion of each large wheel 202. However, the helical drives and crown
gears 228 may
be disposed on an inner portion of each large wheel 202, as is the case for
the embodiments in
Figs. 1, 2, 3, and 4.
A seated user of the wheelchair slides the handle 214 of each helical drive
212 in an up
and down direction causing the helical member in each helical drive 212 to
rotate. The rotation
of the helical drive shaft thereby causes the corresponding pinion gear 216 to
rotate. Each pinion
1 S gear 216 rotates in a manner such that the crown gear is engaged to rotate
in a forward direction.
As a result, the two large wheels 202 are thereby forced to rotate in a
forward direction causing
the wheel chair to move forward.
Fig. 9 illustrates a helical member 230 disposed within the helical drive. The
helical
member 230 comprises a twisted flat bar. A slider 232 forming a thin
rectangular opening has
the helical member 230 disposed therethrough. One end of the helical member
230 is disposed
within a mounting bracket 234. The other end of the helical member 230 is
disposed within a
roller clutch 236. An rod extends from another end of the roller clutch 236
and is disposed
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within a center of a pinion gear 216. An outer rim of the pinion gear engages
the crown gear
238 such that rotation of the pinion gear 216 causes rotation of the crown
gear 238. Thus,
sliding of the slider 232 along a length of the helical member 230 causes the
helical member 230
to rotate, thereby rotating the pinion gear 216 and the crown gear 238.
Fig. 10 shows an embodiment of a helical drive arrangement suitable for use
with a
helical drive wheelchair embodiment in Figs. 5 and 6. Two helical drives are
shown. Each
helical drive 212 includes the helical member 230, a roller clutch 236, a
mounting bracket 234,
and a slider 232 disposed in the manner shown in Fig. 9 and previously
discussed. A handle 240
is attached to the slider 232. An end of each of the helical drives 212 have a
pinion gear.
Disposed between the two pinion gears 216 is a single crown gear 238 such that
each pinion gear
216 is engages the crown gear 238. An axle is disposed through an opening in
the crown gear
238 and is fixedly attached to the crown gear 238. Extending from each
mounting bracket 234
is a rod 242. The rod 242 extends through a center of an output gear 244. A
synchronizing gear
246 is disposed between the two output gears 244. A rod 248 is disposed
through the center of
the synchronizing gear 246. A flange 250 is formed near each of the two ends
of the rod 248.
A pull cable is attached to one end of the rod facing away from the crown gear
238. A spring
254 is disposed around a section of the rod between the synchronizing gear 246
and the flange
250 closer to the pull cable 252.
The helical drive 212 operates in the same manner as discussed previously. The
synchronizing gear serves to preserve a relationship between the movement of a
handle 240 of
one helical drive with the movement of another handle 240 of the other helical
drive 212. By
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pulling on the pull cable 252, readjusting the position of the handles 240,
and releasing the pull
cable 252. the relationship between the handles 240 can be altered.
Fig. 11 shows two helical drives 212 which are similar to the helical drives
shown in Fig.
10. The pinion gear 216 of each helical drive 212 is engages a separate crown
gear 256. An
axle 258 is disposed between the two crown gears 256. This is the same helical
drive used in
the helical drive wheelchair shown in Figs. 7 and 8.
Sliding the handles 258 cause corresponding helical members 230 to rotate. The
rotation
of the helical members 230 cause the corresponding pinion gears 256 to rotate
engaging the
corresponding crown gears 256, thereby causing the crown gears 256 to rotate.
The helical drive provides a constant torque to the wheels of the wheelchair.
Additional
advantages and modifications will readily occur to those skilled in the art.
Therefore, the
invention is not limited to the specific details and representative devices
shown and described
herein. Accordingly, various modifications to the embodiments of the invention
may be made
without departing from the spirit or scope of the invention as defined by the
appended claims and
their equivalents.
Also any embodiment may use other configurations of helical drives, such as,
for example,
a compound helix, or a concentric helix, or a contained helix. Also, motorized
helical drives may
be used.
Transmissions may be provided in the wheel chairs. Mufti-gear hubs on the
drive wheels
may be used, or currently found on some bicycles. Or helical drive mechanisms
can be used with
in-line transmissions.
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The wheel chairs of the present invention can be operated in reverse in the
conventional
manner, by the user manually grabbing the drive wheels and rotating them
backwards manually,
allowing the helical drive mechanisms to free-wheel. Alternatively, reverse
gears can be installed
in the helical drive mechanisms to allow helical driven reverse movement.
The helical drives shown herein deliver power only when the handle is used in
one
direction, and free-wheel when the handle is moved to reset in the other
direction. However,
other helical drives can be used, that give power in the same direction, when
the handle is moved
in both directions, such as the concentric helical drive and compound helical
drive.
Figure 13 shows a compound helix drive for powering a helical wheelchair. A
first
cylindrical screw 200 is disposed closer to an output gear 220 and a second
cylindrical screw 210
is disposed further tom the output gear 220. In this embodiment, each
cylindrical screw 200,
210 is a cylindrical tube with a groove 230 extending in a spiral around the
cylindrical tube and
along a length of the cylindrical tube. The groove 230 on the first
cylindrical screw 200 extends
in a direction opposite to the direction of the groove 230 on the second
cylindrical screw 210.
Extending through the first and the second cylindrical screws 200, 210 is an
axle 240. Two roller
clutches 245 are mounted on the axle 240 such that the axle 240 passes through
the center of
each of the two roller clutches and an outer rim of a respective roller clutch
is in contact with
an inside surface of a corresponding one of the cylindrical screws 200, 210. A
sleeve 25~ of an
input device is slidable disposed along the outer surface of the cylindrical
screws 200, 210. Two
input shafts 248 extend from an inside surface of the sleeve 255 facing toward
a respective one
of the cylindrical screws 200, 210. An end of each input shaft 248 is slidable
disposed, within
a respective groove 230 of a corresponding cylindrical screw 200, 210. An
input device handle
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260 extends outward from an outside surface of the sleeve 255 and passes
through a slot (not
shown) formed on the outer casing (not shown). The slot extends along a side
of the outer casing
in a direction parallel to the lengthwise direction of the two cylindrical
screws 200, 210. A
bearing 275 is disposed around a first end of the axle 240 close to the output
gear 220. The
outer surface of the bearing is .in contact with an inner surface of the first
cylindrical screw 200.
The first end of the axle 240 is disposed within a hole formed in the center
of output gear 220.
A second bearing 275 is disposed around the axle 240, such that the outer
surface of the second
bearing is in contact with an inner surface of the second cylindrical screw
210 close to an end
of the second cylindrical screw 210 opposite to an end closer to the output
gear 220. The second
bearing 275 is attached to an end cap (not shown), which, in turn, is attached
to an inside end
of the outer casing (not shown). A third bearing 275 is disposed around the
axle 240, such that
the outer surface of the third bearing is in contact with an inner surface of
the first cylindrical
screw 200 close to an end of the first cylindrical screw 200 opposite to an
end closer to the
output gear 220. A fourth bearing 275 is disposed around the axle 240, such
that the outer
1 S surface of the fourth bearing is in contact with the inner surface of the
second cylindrical screw
210 near an end of the second cylindrical screw 210 closer to the output gear
220.
Moving the handle 260 of the input device from a position within the slot in
the outer
casing further from the output gear 220 to a position within the slot of the
outer casing near the
output gear causes the input shafts 248 attached to the inner surface of the
sleeve 55 to move
along the grooves 230 of the first and second cylindrical screws, thereby
forcing the second
cylindrical screw 210 to move in a clockwise (when viewed from a direction of
the output gear
220) and the first cylindrical screw 200 to move in a counterclockwise
direction. Moving the
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input device across the slot of the outer casing in an opposite direction
forces the first and second
cylindrical screws 200, 210 to rotate in an opposite direction. When each of
the two cylindrical
screw rotates in the clockwise direction, the roller clutch 245, which is in
contact with. a
corresponding cylindrical screw 200, 210 will cause the axle 240 to remain
stationary. Thus, the
corresponding cylindrical screw 200, 210 is said to be free-wheeling and not
producing any
torque. When each of the two cylindrical screws 200, 210 rotates in a
counterclockwise
direction, the roller clutch 245, which is in contact with a corresponding
cylindrical screw 200,
210, will cause the axle 240 to rotate in the counterclockwise direction. The
rotation of the axle
240 in the counterclockwise direction causes the output gear 220 to rotate in
a counterclockwise
direction.
Figure 14, 15, and 1G illustrate a concentric helix drive for a wheelchair.
Only the
differences from the previous embodiment of a helical drive, shown in Figure
13, shall be
discussed.
Instead of two cylindrical screws as shown in Figure l3, this embodiment
includes a left-
handed (or "LH") slotted helix cylinder 330 and a right-handed (or "RH")
slotted helix cylinder
335, both disposed. within an outer casing 325. The 1ZH slotted helix cylinder
335 is disposed
within the LH slotted helix cylinder 330. A stationary shaft 340 is disposed
through a
longitudinal hole farmed through the RH slotted helix cylinder 335 and
protrudes from two ends
of the RH slotted helix cylinder 335. An annular carrier 377 is disposed
around a portion of the
stationary shaft 340 extending beyond an end of the RH slotted cylinder 335. A
bearing 375 is
disposed around another portion of the stationary shaft 340 protruding beyond
another end of the
RH slotted cylinder 335. The bearing 375 has an annular portion disposod in
contact with an
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inner surface of the LH slotted cylinder 330. A roller clutch 345 has an outer
surface disposed
in ccmtact with the inner surface of the LH slotted helix cylinder 330. The
roller clutch 345 is
disposed around the carrier 377. A bearing 375 is disposed around the
stationary shaft 340 near
an end of the RH slotted helix cylinder 335 further from the output gear 320
and contacts an
inner surface of the RH slotted helix cylinder 335. A roller clutch 345 is
disposed around the
stationary shaft 340 near another end of the RH slotted helix cylinder 335
closer to the output
gear 320 and contacts an inner surface of the RH slotted helix cylinder 335.
An input device
comprises a cylindrically-shaped sleeve 350 having a hole formed in a
longitudinal direction.
The stationary shaft 340 is disposed through the hole formed in the sleeve
350, such that the
sleeve 350 is slidable disposed along the stationary shaft 340. An input shaft
35~ of the input
device extends from an outside surface of the sleeve 350 such that the input
shaft 3~~ is disposed
at an angle substantially perpendicular to the stationary shaft 340 and passes
through a slot 365
formed in the outer casing 32~ and extends in a lengthwise direction along a
length of the outer
casing 325. A shaft roller 357 is disposed on the input shaft 355 such that
the shaft roller 357
is slidable disposed in contact with the RH slotted helix cylinder 335,
Another shaft roller 357
is disposed on the input shaft 3~5 such that the shaft roller is slidable
disposed in contact with
the LH slotted helix cylinder 33U. An output sleeve 379, with two ends, has
one end disposed
through an opening in a central portion of a bearing 375 which is attached to
a central portion
of an output gear 320. The output sleeve 379 extends from the end near the
output gear 320
through a central portion of the roller clutch 345 disposed within a central
portion of the carrier
377.
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Moving the input shaft 355 in a direction toward output gear 320 causes the LH
slotted
helix cylinder 330 to rotate in a clockwise direction, when viewed from an end
of the helical
drive having the output gear 320, and causes the RH slotted helix cylinder 335
to rotate in a
counterclockwise direction. Moving the input shaft 355 in a direction away
from the output gear
320 causes the LH slotted helix cylinder 330 to rotate in a counterclockwise
direction and the RH
slotted helix cylinder 335 to rotate in a clockwise direction. When either the
LH slotted helix
cylinder 330 or the RH slotted helix cylinder 335 is rotated in the cloch'wise
direction, the
respective roller clutch 345 causes the output sleeve 379 to rotate in the
clockwise direction.
When the output sleeve 379 rotates in the clockwise direction, the outer rim
of the output gear
320 rotates in the clockwise direction.
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