U.S. patent number 3,602,522 [Application Number 04/799,411] was granted by the patent office on 1971-08-31 for wheel chair.
Invention is credited to Rodvinon I. Zamotin.
United States Patent |
3,602,522 |
Zamotin |
August 31, 1971 |
WHEEL CHAIR
Abstract
A self-propelled wheel chair having two sets of endless belts
and retractable wheels for ascending and descending irregular
inclined surfaces such as stairs. A flip-decelerating shock
absorber using standard hydraulic means eases the movement over an
edge from a level surface to a downwardly inclined surface. The
long primary endless belts are used for ascending and descending
stairs, and the shorter, secondary belts mounted rearwardly of the
primary belts and drivingly engaged therewith, are used for
climbing and descending curbs and the like. An improved arrangement
is provided for retracting the main wheels. An improved drive is
provided between the main wheels and the primary belts, and an
improved clutch permits selective driving engagement and
disengagement between the main wheels and the primary belts.
Inventors: |
Zamotin; Rodvinon I. (Miami
Springs, FL) |
Family
ID: |
25175848 |
Appl.
No.: |
04/799,411 |
Filed: |
February 14, 1969 |
Current U.S.
Class: |
280/5.22;
192/69.4; 192/69.9 |
Current CPC
Class: |
A61G
5/066 (20130101); A61G 5/061 (20130101) |
Current International
Class: |
A61G
5/06 (20060101); A61G 5/00 (20060101); A61g
005/00 () |
Field of
Search: |
;180/9.24 ;280/5.22
;192/67,108 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Johnson; Richard J.
Claims
I claim:
1. A wheel chair capable of travelling on inclined irregular
surfaces comprising a pair of side frames defining a seat
therebetween; each of said side frames comprising: guide means, and
endless belt on said guide means and having an upper run and a
lower run, the lower run of said endless belt defining a generally
V-shaped path from a front end in front of the seat to a rear end
behind the seat, a main wheel rotatably mounted on the side frame
and movable at least between a raised position above the said lower
run and a lower position whereat the bottom of the wheel is
positioned below the said lower run for engaging the ground, and a
rear leg having a rear wheel movable at least between a raised
position above the lower run and a lower position sufficiently far
below the lower run such that the chair is upright when the rear
wheel is lowered, and wherein, when the main and rear wheels are in
their raised positions, the rear part of the V-shaped lower run
engages the ground, means for driving the endless belt about its
guide means, a hydraulic shock absorber means operatively
associated with said side frame for movement between a raised
position above the level of the lower run and a lower position
below the lower run, said shock absorber means comprising a bar
extending forwardly along the rear part of the V-shaped lower run
from a pivot connection with the side frame, such that when the
wheel chair is supported on the said rear part of the lower run for
movement along a surface onto a downward incline, said bar is
pivotable about said pivot connection to its lower position to
engage the inclined surface before the chair tips over a sufficient
amount for the said rear part of the lower run to engage the
incline, a retaining means for holding the bar in its raised
position and a spring means for urging the bar to its lower
position when the retaining means is released, a damping mechanism
operatively associated with the bar, said mechanism permitting
movement of the bar downwardly away from the lower run under the
action of the spring means and restricting movement of the bar
upwardly to its raised position, said damping mechanism including a
hydraulic piston and cylinder unit operatively connected to the
side frame and to the bar, a fluid reservoir, an open passage from
one end of the cylinder to the reservoir to permit free passage of
fluid therein as the bar moves to its lower position, and two fluid
lines leading from the reservoir to the other end of the cylinder,
one of said two lines being a restricted passage and the other
having a one-way valve permitting fluid to flow only from the
reservoir to the cylinder, whereby when the bar is lowered, liquid
flows from the reservoir through the one-way valve to the cylinder,
and wherein during raising of the bar, liquid flows through the
restricted passage to the reservoir.
2. A wheel chair according to claim 1 including a retaining rod
means attached to the bar, and locking means attached to the side
frame and operatively engageable with the retaining rod for
releasably holding the bar in the raised position. 3A wheel chair
capable of travelling on inclined irregular surfaces comprising a
pair of side frames defining a seat therebetween; each of said side
frames comprising; guide means, an endless belt on said guide means
and having an upper run and a lower run, the lower run of said
endless belt defining a generally V-shaped path from a front end in
front of the seat to a rear end behind the seat, a main wheel
rotatably mounted on the said frame and movable in an arc at least
between a raised position above the said lower run and a lower
position whereat the bottom of the wheel is positioned below the
said lower run of the endless belt for engaging the ground, and a
rear leg having a rear wheel movable at least between a raised
position above the lower run and a lower position sufficiently far
below the lower run that the chair is upright when the rear wheel
is lowered, and including a means for moving the main wheel to said
raised and said lowered positions, comprising a swing plate
pivotally connected at one end to the guide means and having
rotatably connected to its forward end the shaft of the said main
wheel, said plate being pivotable about said pivot connection for
raising and lowering the main wheel, a slot in the rear part of the
swing plate, a lever arm pivotably connected at its lower end to
the guide means and extending upwardly, said lever arm including a
pin engageable in the slot of the swing plate, the pin and slot
being arranged such that movement of the lever arm in one direction
about its pivot connection raises the main wheel and movement of
the lever arm in the other direction about its pivot connection
lowers the main wheel, the slot being shaped such that movement of
the lever arm through one-half of its range of movement causes
movement of the main wheel between its lower position and an
intermediate position just clearing the lower run, and movement of
the lever arm through the other half of its range of movement
causes a larger movement of the main
wheel from the intermediate position to the raised position. 4. A
wheel chair according to claim 3 including a raised cam fixed to
the side frame and having a forward end and a rear end, and wherein
the said lever arm engages the forward and rear end of said raised
cam to be locked in said
lowered and raised positions, respectively. 5. A wheel chair
according to claim 3 including a sprocket mounted on the shaft of
the main wheel and a chain engaging said sprocket and drivingly
engaged with the endless belt for driving the endless belt in
response to movement of the main wheel.
A wheel chair according to claim 5 including a clutch means on the
said shaft for selectively engaging and disengaging the main wheel
with the said sprocket. 7A wheel chair capable of travelling on
inclined irregular surfaces comprising a pair of side frames
defining a seat therebetween; each of said side frames comprising:
guide means, an endless belt on said guide means and having an
upper run and a lower run, the lower run of said endless belt
defining a generally V-shaped path from a front end in front of the
seat to a rear end behind the seat, a main wheel rotatably mounted
on the side frame and movable at least between a raised position
above the said lower run and a lower position whereat the bottom of
the wheel is positioned below the said lower run for engaging the
ground, and a rear leg having a rear wheel movable at least between
a raised position above the lower run and a lower position
sufficiently far below the lower run that the chair is upright when
the rear wheel is lowered, and including a clutch means for
selectively placing the endless belt into driving engagement with
the main wheel said clutch means including a first member attached
to the shaft of the main wheel for rotation therewith and a second
member freely mounted on said shaft, a sprocket attached to the
second member to receive a chain for driving the endless belt, and
an annular clutch member having an internal surface shaped to
drivingly engage said first and second members, said clutch member
being slidable on said first and second members to a first position
where it engages only one of said members and a second position
where it drivingly engages both of said members for transferring
torque from the first member to the second member, a spring acting
on the flange to urge the clutch member to the said second position
and a pressure plate arranged to act on the annular flange to urge
the clutch member to the first position, and including a cam
mounted to act on the pressure plate for urging the clutch member
to the said first position, and a stem operatively connected to the
cam for turning the same, said stem extending upwardly to the top
of the side frame and accessible for rotation by the operator to
operate the clutch. 8A wheel chair capable of travelling on
inclined irregular surfaces comprising a pair of side frames
defining a seat therebetween; each of said side frames comprising;
guide means, a primary endless belt on said guide means and having
an upper run and a lower run, the lower run of said primary endless
belt defining a generally V-shaped path from a front end in front
of the seat to a rear end behind the seat, a main wheel rotatably
mounted on the side frame and movable vertically, relative to the
frame at least between a raised position above the said lower run
and a lower position whereat the bottom of the wheel is positioned
below the said lower run for engaging the ground, and a rear leg
having a rear wheel movable vertically at least between a raised
position completely above the lower run and a lower position
sufficiently far below the lower run that the chair is upright when
the rear wheel is lowered, and including a secondary belt assembly
comprising a secondary guide means and a secondary endless belt
mounted thereon and having an upper run and a lower run, said
secondary guide means being connected at its forward end to the
said primary guide means at a fixed point above the said lower run
of the said primary endless belt and rotatable about said fixed
point, the rear end of the secondary guide means being operatively
connected to the rear leg for movement with the rear wheel between
said raised and said lowered positions, the said secondary guide
means being arranged such that when the rear wheel is in its lower
position, the lower run of the secondary endless belt inclines
forwardly upwardly at an incline about one-half that of the front
part of the "V" of the primary endless belt, and such that when the
rear wheel is fully raised, the secondary endless belt and the
secondary guide means move about said fixed point and lie parallel
to and above the lower run of the first said belt, and means for
driving the
secondary belt as the primary belt is driven. 9. A wheel chair
according to claim 8 wherein the guide means includes a drive
pulley selectively drivingly engageable with the said main wheel,
and power takeoff means drivingly engaging the drive pulley of the
primary guide means with the drive pulley of the secondary guide
means so that the secondary endless
belt is driven whenever the primary endless belt is driven. 10. A
wheel chair as claimed in claim 8 wherein the rear leg is located
outside of the side frame and the secondary guide means is located
inside the side frame, the said connection between the rear leg and
rear end of the secondary guide means including a bar extending
upwardly from said secondary guide means and over the side frame
and fixedly connected to the upper end of
the rear leg. 11. A wheel chair capable of travelling on inclined
irregular surfaces comprising a pair of side frames defining a seat
therebetween; each of said side frames comprising: guide means, an
endless belt on said guide means and having an upper run and a
lower run, the lower run of said endless belt defining a generally
V-shaped path from a front end in front of the seat to a rear end
behind the seat, a main wheel rotatably mounted on the side frame
and movable at least between a raised position above the said lower
run and a lower position whereat the bottom of the wheel is
positioned below the said lower run for engaging the ground, and a
rear leg having a rear wheel movable at least between a raised
position above the lower run and a lower position sufficiently far
below the lower run that the chair is upright when the rear wheel
is lowered, and wherein said rear leg includes a means for
automatically aligning the rear wheel in the reverse position,
including a caster mounting on said rear wheel, an incline cam
attached to the upper section of the caster, presenting an upwardly
facing surface completely surrounding the rear leg and having a low
point, and a rod vertically slidable along the rear leg and
arranged, through spring loading, to engage the cam plate and turn
the rear wheel, if necessary, until the rear wheel clears the
endless belt when the leg is in the fully raised position.
Description
BACKGROUND
This invention relates to wheel chairs. More particularly, this
invention relates to a self-propelled wheel chair capable of
ascending and descending irregular inclined surfaces such as steps,
curbstones etc. as well as travelling on flat, or substantially
flat surfaces.
There are many individuals who must spend considerable time without
the use of their legs while recuperating from physical injury and
many more individuals who are permanently unable to walk. The wheel
chair provides a relatively inexpensive device to aid such people
to travel about by themselves and thereby regain a measure of
normal mobility. Thus, the invalid is enabled, by using his arms
and hands, to travel about on smooth level surfaces and on smooth
gentle slopes. In order to traverse steep slopes, it is necessary,
with the ordinary wheel chair, to enlist the aid of a helper to
either push the chair from behind or restrain the chair from
rapidly descending a steep slope. To obviate the need of a helper,
specialized expensive motorized vehicles have been developed
whereby motor power can be applied to the wheels to drive the
chair. As it is necessary, to enter and leave most homes and
buildings, that the wheel chair traverse steps, it has been
necessary to provide ramps for the use of people confined to wheel
chairs. It is now common to observe such ramps provided in private
homes and public buildings and a great many new well planned public
buildings include such ramps in their original design. There
remain, however, a large majority of buildings with no such
provision and in addition, there are many obstacles such as
curbstones which are all but impossible to traverse, unaided, in an
ordinary wheel chair. And it is further impossible to traverse an
ordinary flight of steps, even with aid. In such situations the
whole chair must be lifted and carried by two persons.
A wheel chair which overcomes at least some of the aforementioned
disadvantages is disclosed and claimed in my previous U.S. Pat. No.
3,259,396, patented July 5, 1966. My said previous patent is
incorporated by reference in this application, not only for its
teaching of the basic concepts of a retractable wheel, endless belt
wheel chair, but also for some of the more specific features such
as the construction of the endless belt, the construction of the
clutches and the construction of the means for retracting and
extending the rear wheels.
Although the apparatus shown in my said previous patent represents
a significant advancement in the art, certain problems have arise
in practice.
One of these problems concerned the movement of the wheel chair
over an edge such as from a level surface onto a staircase to
commence descending the staircase. With my previous arrangement,
this descending movement is carried out by first retracting the
rear wheels so that the wheel chair rests on the rear portion of
the endless belt. The wheel chair is then moved by means of these
endless belts outwardly from the level surface over the descending
surface. The chair retains its original orientation during the
forward movement until the center of gravity passes the edge of the
level surface and is also over the inclined surface, at which time
the whole chair swings about the edge until the endless belts
contact the inclined surface. However, this procedure has been less
than satisfactory since the said swinging movement is often very
sudden, and indeed almost frightening since it often appears that
the chair could tumble down the incline. Therefore, there exists a
need for a means to facilitate movement of an endless belt-type
wheel chair from a level surface over an edge to a downwardly
inclined surface.
Another problem in the prior art is the task of climbing a curb.
One means for accomplishing this purpose is shown in my said
patent. However, the means shown therein is often difficult to
maneuver. Thus, there exists a continuing need for new and improved
means for negotiating curbs.
In addition, of course, there exists a continuing need for
improving various parts of the apparatus, including, for example,
the means for retracting and lowering the main wheels, the means
for driving the endless belt from the main wheels and the clutch
means for selectively drivingly engaging the endless wheels with
the main wheels.
SUMMARY OF THE INVENTION
Thus, a purpose of this invention is to provide a new and improved
wheel chair of the type capable of both operating on a flat surface
and also negotiating irregular inclines such as curbs and
stairs.
In accordance with this purpose of the invention there is provided,
in a wheel chair of the type described, a shock absorbing apparatus
for eliminating the sudden drop which has occurred heretofore as
the center of gravity of the wheel chair passed over the edge of a
flat surface onto a downwardly inclined surface. In accordance with
another feature of the invention there is provided a second endless
belt, preferably in driving engagement with the first endless belt,
and mounted with respect to the rear wheels such that the second
endless belt rather than the rear wheels engages the edge of the
curb during both climbing and descending curbs.
In accordance with another feature of the invention there is
provided an improved means for retracting and lowering the main
wheels. This arrangement includes a lever which, through half of
its movement, causes slight movement of the main wheels off the
ground (just enough to clear the endless belt), and through the
other half of its movement raises the wheels a substantial distance
above the level at which the endless belt engages the ground.
In accordance with another feature of the invention there is
provided an improved drive means for driving the endless belt (or
belts), by turning the main wheels. In particular, this new and
improved driving engagement includes providing internal teeth on
the drive pulley of the endless belt, and arranging a plurality of
spur gears within this driving pulley and in engagement with the
internal teeth. One of these spur gears may have mounted on its
shaft a sprocket with a chain for receiving the drive from the main
wheels. This arrangement permits a three to one gear reduction,
thereby increasing the mechanical advantage by decreasing the
amount of work necessary to move the wheel chair. Another one of
these internal spur gears in engagement with the internal teeth on
the drive pulley includes a sprocket with a chain for driving the
said second endless belt. The third spur gear includes a ratchet
and constitutes a means for permitting movement of the driving
pulley in forward or reverse.
In accordance with another feature of the invention there is
provided an improved simplified clutch means for selectively
placing the main wheels into or out of driving engagement with the
endless belt.
Thus, it is a purpose of this invention to provide a new and
improved wheel chair of the type described for ascending and
descending irregular inclined surfaces as well as for travelling on
a substantially flat surface.
It is another object of this invention to provide a new and
improved means for facilitating movement of a wheel chair of the
type described from a level surface over an edge onto a downwardly
inclined surface.
Another object of this invention is to provide a new and improved
means for retracting and lowering the main wheels.
It is another object of this invention to provide, in a wheel chair
of the type described, a new and improved means for driving the
endless belt from the main wheels.
It is another object of this invention to provide a simplified
clutch arrangement for selectively placing the main wheels into or
out of driving engagement with the endless belt.
Other objects and the attendant advantages of the present invention
will become apparent from the detailed description to follow
together with the accompanying drawings.
BRIEF SUMMARY OF THE DRAWINGS
The wheel chair of the present invention comprises two symmetrical
side parts containing the various mechanical features of the
invention and a foldable flexible center part including the seat
and back connecting these two main side parts. Therefore, to
simplify the discussion of the invention only one of these main
side parts will be illustrated in detail. For an overall
perspective view of a wheel chair of the present type, and for an
illustration of the foldable flexible back and seat between the two
sides, reference is made to my said previous U.S. Pat. No.
3,259,396.
In the Drawings:
FIG. 1 is an outside elevational view of the left side frame of a
wheel chair constructed in accordance with the present
invention.
FIG. 2 is a view similar to FIG. 1, but showing, in solid lines,
only fixed frame elements of the wheel chair.
FIG. 3 is a side elevational view similar to FIGS. 1 and 2 and
showing additional features of the wheel chair.
FIG. 4 is a detailed view of the portion of FIG. 3 associated with
the shock-absorbing mechanism.
FIG. 5 is a partial plan view taken along line 5--5 of FIG. 3.
FIG. 6 is an enlarged, perspective view of the rear wheel of FIG.
3.
FIG. 7 is a rear elevational view taken along line 7--7 of FIG.
3.
FIG. 8 shows the side of the left main frame opposite from that
shown in FIGS. 1-3, emphasizing the fixed frame parts and wherein
the front, central and rear plates facing the viewer have been
removed to show internal parts.
FIG. 9 is a side elevational view similar to FIG. 8 but showing
additional structural features of the invention.
FIG. 10 is a detailed plan view of a clutch mechanism taken along
line 10--10 of FIG. 9.
FIG. 11 is a front elevational view of the clutch mechanism of FIG.
10, and is taken along line 11--11 of FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, FIGS. 1-11 all relate to the left
side frame of the wheel chair, it being understood that the right
side frame of the wheel chair is symmetrical with the left side and
is connected thereto by means of a foldable seat and back section
as shown in my previous U.S. Pat. No. 3,259,396. Like elements are
represented by like numerals throughout all of the figures.
FIG. 1 illustrates the complete left side frame of the wheel chair,
showing all of the elements of the preferred embodiment. However,
in the subsequent views various parts of the preferred embodiments
are omitted for purposes of clarity.
FIGS. 2 shows, in solid lines, those elements which constitute the
fixed rigid parts of the left side frame 10. This fixed frame
includes a horizontal arm rest bar 11 having a downwardly extending
front part 11a. Parallel to the bar 11 is a central horizontal bar
12 connected to the bar 11 by a front bar 13 and an upper central
vertical bar 14. The lower and rearward part of the side frame, as
shown in FIG. 2, constitute the guide parts for guiding the endless
belt. This guide part comprises a pair of front plates 16, a pair
of central plates 17 and a pair of rear plates 18. Suitable pulleys
and drive wheels are located between the pair of plates 16, the
pair of plates 17 and the pair of plates 18 for driving and guiding
the main endless belt. A front upper guide rail 19 and a front
lower guide rail 20 extend between and connect the sideplates 16
and the sideplates 17. Similarly, a rear upper guide rail 21 and
rear lower guide rail 22 extend between and connect the central
plates 17 and the rear plates 18. A connecting piece 23 extends
between and is connected to the rails 21 and 22. A lower central
vertical bar 15 extends from the bar 12 to the bar 21. And finally,
a pair of fixed bars 24, extending downwardly from the central
horizontal bar 12, from a frame onto which a foot pedal is mounted.
This particular feature is shown in greater detail in FIG. 9.
For placing the fixed rigid parts into proper context, there is
also shown in FIG. 2, in dotted lines, the main moving parts of the
wheel chair, including the main endless belt 25, a crawler belt 26,
the main wheel 27 of the wheel chair (shown in its downward
position) the central shaft 28 of the wheel 27, the back wheel 29
and the vertically movable rear leg 30 to which the back wheel 29
is attached.
As explained in detail in my said previous patent, and as explained
in greater detail below, in order to ascend a flight of stairs, the
operator backs up to the flight and raises the rear leg 30 and the
entire rear leg structure upwardly so that the portion of the
endless belt beneath the rear lower guide rail 22 engages the
stairs. As explained in greater detail below, the entire structure
associated with the crawler belt 26 is connected to the rear leg
and the rear wheel structure such that when the rear leg is raised,
the crawler structure is also raised. As a result, as in the case
of my previous patent, the portion of the endless belt beneath the
guide rail 22 engages the flight of steps for ascending the said
flight. Similarly, as explained in my said previous patent and as
explained in greater detail below, to descend a flight of stairs,
the operator approaches the stairs with the rear wheels fully
retracted and with the wheel chair resting on the portion of the
endless belt beneath guide rail 22. The wheel chair is then moved
slowly, and horizontally, over the stairs themselves until the
center of gravity passes over the edge. At this point the chair
tips forward until the position of the belt beneath guide rail 22
engages the downwardly inclined surface such as the edges of the
steps.
However, until now this procedure for advancing over the top of the
incline has had at least one substantial disadvantage. In practice,
the "tipping over" motion is not gradual. Rather, there is a sudden
drop which is almost frightening. If the incline is great enough,
one almost obtains the feeling that the chair will continue to fall
forward, tumbling down the stairs.
To overcome this disadvantage, the present invention includes a
shock absorbing means for permitting the wheel chair to "tip over"
very gradually from its horizontal position to its inclined
position. This shock absorbing means is shown in FIG. 3 and it is
shown in greater detail in FIG. 4.
Referring now to FIGS. 3 and 4, there is shown a shock absorber
assembly 35 comprising a hinged bar 36 mounted for pivotal movement
about pivot pin 37 which is in turn connected to guide rail 22. The
assembly includes a cylinder 38 containing actuating fluid,
preferably hydraulic fluid. This cylinder is fixed to the plate 11a
and includes the said hydraulic fluid above and below a piston 39.
A piston rod 40 is connected to the piston 39 and extends down to
the bar 36, to which it is pivotally attached at point 41. The rod
40 includes a collar 42 fixed thereto and a spring 43 acting
between the cylinder 38 and the collar 42 and normally urging the
hinged bar 36 to pivot counterclockwise about the pivot pin 37. The
assembly also includes a retaining rod 44 pivotally connected at
its lower end to bar 36 and extending through a guide sleeve 44
(which guide sleeve is attached to the arm rest bar 11). This rod
44 contains a through opening 47 near its upper end, into which
opening a tapered slidable lock bolt is slid to hold the rod 44 in
its upper position and hence also to hold the bar 36 in its upper
(or clockwise) position against the force of spring 43.
The shock absorber assembly 35 also includes a hydraulic tank 49
having an unrestricted fluid passage 50 leading to the lower end of
the cylinder 38. The tank is connected to the upper end of cylinder
38 through a restricted passage 51 and through a second passage 52,
parallel to the passage 51, including a one-way valve 53 permitting
fluid to flow from the tank 49 to the cylinder 38.
The shock absorber assembly 35 operates as follows. As the operator
edges over the upper edge of the incline, the elements are in the
position as shown in FIG. 3, and as shown in solid lines in FIG. 4.
After the operator has edged past the upper edge of the incline a
sufficient amount, but before the center of gravity has passed over
the upper edge, the operator withdraws the lock bolt 48 by pulling
it rearwardly, thereby releasing the rod 44 and permitting the bar
36 to more downwardly (counterclockwise as shown in the figures)
under the force of spring 43 until the bar engages the incline.
This may be, for example, the dotted line position shown in FIG. 4.
During this downward movement of the various elements, any fluid
beneath piston 39 is permitted to flow freely through line 50 to
the tank 49. The operator then continues to edge forward until the
center of gravity passes over the edge. At this point, as with the
previous arrangement, the wheel chair starts to tip over from the
level surface onto the inclined surface. Now, however, this
movement of the chair to the incline position can occur only by
pushing the bar 36 upwardly, and hence pushing the piston 39
upwardly into the cylinder 38. However, upward movement of the
piston 39 is resisted by the fluid in the upper part of chamber 38,
which fluid can escape only slowly through restricted passage 51.
This restricted escape of the fluid constitutes the shock absorbing
mechanism. Of course, during downward movement of the piston 39
fluid is permitted to flow freely from the tank 49 to the upper
part of cylinder 38 through line 52 and one-way valve 53. Finally,
when the chair has reached the fully inclined position, the bar 36,
and hence the rods 40 and 44 will have been pushed upwardly
(clockwise) to their uppermost position, at which time the operator
simply moves the sliding lock bolt 48 forwardly through aperture 47
to lock the shock absorber mechanism in its retracted position.
The elements 44 and 48 are shown also in FIG. 5.
The rear leg and the rear wheel of the wheel chair, as shown for
example in FIG. 3, operate in substantially the same manner as the
corresponding parts in my said previous patent. However, there are
some modifications. The front of the rear leg 30 is formed as a
toothed rack 61 which meshes with the teeth of a spur gear 62 which
is mounted for rotation about a pin attached to the rear plates 18.
A sprocket wheel 65 is mounted coaxially with the spur gear 62 for
rotation therewith. A chain loop 66 engages the sprocket 65 at one
end and a second sprocket 67 at its other end. This other sprocket
is mounted on frame part 11b. A hand wheel 68 convenient to the
operator is fixed for rotation with the sprocket 67 such that by
turning the hand wheel 68 the operator turns the sprocket 67, and
thus turns the chain 66 and the sprocket 65 to raise and lower the
rear leg 30. This rear leg is supported on the side opposite from
spur gears 62 by a pair of H-shaped rollers 63. See FIGS. 3 and 7.
Downward and upward vertical movement of the rear leg 30 is limited
by engagement of stop members 64a and 64b on the rear leg 30 with
the spur gear 62. In FIG. 3, the rear leg 30 is shown in its
lowermost position whereat the stop member 64a engages the spur
gear 62.
FIG. 3 also shows a portion of the crawler assembly including the
crawler belt 26. The purpose of this assembly will be explained in
greater detail below. However, for the present it should be noted
that the lowermost point of this assembly is slightly above the
bottom of wheel 29, for example, one-fourth of an inch. This
crawler assembly must retain its orientation relative to wheel 29
and it must move upwardly as the wheel 29 moves upwardly so that
the portion of the endless belt 26 adjacent lower guide rail 22 can
ride on an inclined surface. For this purpose, the rear frame
members of the crawler assembly are rigidly attached to the rear
leg 30 by means of a rod 92 which is rigidly attached at its upper
end to a portion of leg 30 which bends over the rear plates 18. See
FIGS. 3, 7 and 9.
As explained in detail in my previous patent, there is associated
with sprocket member 67 a clutch arrangement for permitting
movement of the hand wheel 68 in only one direction at a time. This
clutch 69 is mounted on the opposite side of plate 11b from
sprocket 67. See FIG. 9. The upper part of this clutch mechanism 69
is attached to a plate 70 which is in turn attached to the arm rest
bar 11. See FIG. 5.
When approaching a flight of stairs, or any other incline in
preparation for an ascent or a descent, it is necessary that the
direction of the rear wheels be locked to permit only forward and
reverse movement while preventing turning movement. To achieve this
result, the present invention now includes an automatic rear wheel
castor locking device. Referring to FIGS. 3 and 6-8 there is
provided an inclined cam surface 75 circumventing the rear wheel 30
and connected to the castor by a connecting piece 76. This inclined
circular cam includes a low point 77. Meanwhile, a cooperating rod
78 is mounted on the rear leg 30 through guides 80. A spring 81
acting between the guide 80 and a collar 82 fixed on the rod 78
urges the rod 78 downwardly. Meanwhile, any convenient holding
means is employed to hold the rod 78 in its position against the
action of spring 81. For locking the casters, the rods 78 are
simply released and permitted to move downwardly. At this time the
lower tip 79 of the rod 78 engages the circular cam 75 and exerts a
downward force thereon thereby turning the cam plate 75 and hence
also the wheel 29 until the low point 77 is positioned directly
below and in contact with the said tip 79. At this time the rear
wheel is correctly oriented for commencing an assent or a descent
of an inclined surface.
FIGS. 7, 8 and 9 also show the structure for holding the back and
the seat which support the operator. A vertical bar 95 (see FIGS. 7
and 9) is rigidly attached to the rear plates 18. A flexible
material 96 constituting the back of the chair is attached to and
extends across from this bar 95. Meanwhile, the seat 98 is attached
to a bar 97 (see FIGS. 7 and 8) and is movable about the axis of
bar 97 for folding the seat.
Another feature of the present invention is the provision of a
crawler belt assembly for permitting the wheel chair to negotiate
obstacles and inclinations which are too small to be negotiated by
the main endless belt 25 and too large to simply roll directly
over. The most frequent example of this type of obstacle is a curb.
The crawler assembly, including the crawler endless belt 26 is
provided for this purpose. See FIGS. 3 and 7-9. Referring in
particular to FIGS. 8 and 9, this crawler assembly includes a pair
of rear crawler plates 85 and a pair of front crawler plates 86,
the two pairs of plates being connected to each other by means of
guide bar 87. In FIG. 8, the plates 85 and 86 closest to the viewer
have been removed to expose the area between these plates. The
crawler belt 26 is a timing belt of the same construction of the
main belt (as described in detail in my previous patent). This
crawler belt is mounted for rotation about a driving wheel 89
having teeth which engage grooves in belt 26. An idler pulley 88 is
provided between the rear plates 85. The drive pulley 89 has a
square central opening which is positively engaged by a square
portion of shaft 90. On each side of the drive belt 89, the shaft
90 is circular and it extends through the two plates 86. On the
side of plates 86 opposite from that shown in FIG. 9, the shaft 90
has a chain sprocket fixed thereon for rotation therewith. Beyond
this point the shaft 90 passes through the lower guide rail 22. A
chain 121, which will be explained in greater detail below (see
FIG. 9), engages the sprocket of the shaft 90 to rotate the shaft
90, and hence the drive pulley 89 and the crawler belt 26 whenever
the main endless belt 25 is moved. At the rear end of the crawler
assembly there is provided a small wheel 91 which keeps the rear
wheels from digging in and turning sideways as the wheel chair is
climbing curbs.
Thus, in operation, one would ascend a curb by first wheeling the
chair up to the curb, and then retracting the wheels and operating
the belts. The portion of the main belt adjacent guide rail 20
would first engage the curve and climb until the lowermost point of
the main belt cleared the edge of the curve. Shortly thereafter,
the lower portion of the crawler belt 26 adjacent the bar 27 would
engage the curb, and upon further movement of the two belts, the
wheel chair would complete its ascent of a curb. To descend a curb,
the operator goes front end first. In this case, whether the main
wheels are retracted or in the down position, after main part of
the wheel chair went over the curb, the latter part would be caught
by the engagement of crawler treads 26 with the edge of the
curb.
When the rear wheels are retracted, (raised) the entire crawler
assembly pivots about the round portion of shaft 30 pivotally
engaged in guide rail 22, such that in the fully raised position of
the rear legs and rear wheels, the entire crawler assembly is
located above that portion of the belt below guide rail 22 so that
the main endless belt can be used for ascending or descending a
flight of stairs.
FIGS. 8 and 9 show the driving arrangement of the preferred
embodiment of the invention. Referring first to FIG. 8, which shows
the wheel chair with the sideplates removed, the drive arrangement
includes a driving pulley 110 having teeth formed on its external
surface for engaging the grooves in the main endless belt 25 which
is a timing belt as described in my previous patent. The path of
the belt 25 is established by means of idler pulley 111 and 112
connected to the central plates 17 and the idler pulleys 113 and
114 connected to the rear plates 18. This driving pulley 110 is an
internally toothed ring gear having a plurality of spur gears 115,
116 and 117 in engagement therewith. Each of these spur gears
115-117 are mounted on shafts extending through the sideplate 17 as
shown in FIG. 9. Chain sprockets 115a, 116a and 117a are mounted on
the shafts of gears 115, 116 and 117, respectively, for rotation
with said shafts. The sprocket ii5a is engaged by a chain 118
which, at its other end, is engaged by a sprocket which is
selectively engageable with the shaft of main wheel 27 for rotation
therewith. Therefore, by actuation of a simple clutch mechanism (to
be described in greater detail below), turning of the wheel 27
turns the chain 118, and hence the sprocket 115a. This in turn
turns the member 110 which drivers the main belt 25. The sprocket
117a, turned by its connection with spur gear 117, then acts as a
power takeoff mechanism for turning chain 121, shaft 90 and hence
the crawler thread 26. Meanwhile, the sprocket 116a, which is
engaged through chain 119 to a sprocket rigidly attached to wheel
120, acts as a clutch mechanism for permitting rotation of the
drive wheel 110, and hence of the endless belt 25, in either the
forward or the reverse direction.
This improved drive arrangement has a number of advantages. First
of all, the ring gear 110 provides a reduction of three-to-one for
more power. Secondly, the provision of elements 117 and 117a, in
combination with the ring gear, provide a compact source for power
takeoff for the crawler. This is particularly important since it
has been found that the crawler must be driven positively in order
to work effectively. The spur gear 116a has a three-eighth inch
hole in its shaft and receives a standard ratchet such as made by
S-K. This clutch may be of the type described in my previous
patent. The ratchet wrench is drilled and the wrench is then bolted
to a bolt coming out of the frame assembly approximately in the
center between the spur gears. That portion of the wrench which
operates the ratchet control has the sprocket 116a welded to it,
from which the chain 119 extends to a sprocket on the wheel 120. By
turning this wheel 120 the proper amount, the operator sets the
drive in forward or reverse.
Another feature of the invention is the improved lever and cam
arrangement for retracting and lowering the front wheels. This
structure is shown in detail in FIG. 9 and portions are further
illustrated in FIG. 10. The shaft 28 of the main wheel 27 passes
through a swing plate 130 which is pivotally connected at the end
opposite from shaft 28 on a pivot pin 132 which is in turn fixed on
the connecting piece 23. This swing plate includes an elongated
curved slot 131. In addition, the arrangement includes an elongated
bent lever arm 133 pivotally connected at one end by means of pin
134 in the guide rail 22 and having fixed thereto a pin 135 which
engages the slot 131.
As shown in FIG. 8 as well as FIG. 9, a fixed plate 140 is located
near the upper part of the frame, this plate being rigidly fixed to
vertical bars 13 and 14. A raised member 141 is fixed to the plate
140 and includes abrupt ends 141a and 141b. Referring now to FIG.
9, the elements are shown in solid lines in the wheel down
position. In this position there is a general force tending to urge
the lever 133 counterclockwise about its pivot point 134. This
motion is resisted by engagement of the upper end of lever arm 133
with the end 141a of the raised cam surface 141. To retract (raise)
the wheels, the operator grasps the upper end of lever arm 133 and
pulls the arm rearwardly (counterclockwise). By this movement, the
pin 135, acting in the slot 131 turns the plate 130
counterclockwise about its axis 132 and thereby raises the wheels
to a level above the low point of the track 25. In this retracted
position, which is shown in dotted lines in FIG. 9, the lever arm
133 rests against the opposite end 141b of the cam 141. The lever
133 is held against edge 141b by the weight of the wheels acting
through plate 130 on the pin 135, and also by spring 136 acting
between the plate 130 and the lever arm 133. This system has the
advantage that the slot is so engineered that half of the stroke of
the lever arm moves the plate 130 a very small amount (that
distance which brings the wheel down past the frame) and the other
half stroke gives a long travel to the swing plate so that the
wheel can clear the belt line so that the chair can climb the
stairs.
Normally the belts are in driving engagement with the wheel 27 so
that by turning the wheel (when the wheel is in its retracted
position), the operator moves the belts. However, when the wheels
are down for normal use on level ground, this driving engagement
between the wheels 27 and the belt causes an unnecessary drag which
must be overcome in order to move the chair. Consequently, in
accordance with another feature of the invention, there is provided
a simple clutch for selectively disengaging the belts from the main
wheels for normal use of the wheel chair on level ground. This
simple clutch mechanism is located on the shaft 28 between the
plate 130 and the wheel 27, and is shown in detail in FIGS. 10 and
11.
Referring to these figures, the positive clutch 149 includes a
shaft assembly 150 rotatable with the wheel 27. This shaft assembly
includes a flat annular plate 151, a hexagon-shaped portion 152
ending at shoulder 153 and a reduced diameter circular portion
shown at 154. This reduced diameter circular portion 154 extends
outwardly to the left (as shown in FIG. 11) to the very end except
for the outermost portion which includes a threaded part 155 which
is engaged by a nut 160 for a purpose to be described below.
Mounted on this reduced portion 54 for rotation relative thereto,
there is provided a sprocket member 156 including a first side 157
which has a hexagon shape identical to the shape of hexagon portion
152. The central part of this member 156 is a sprocket 158 which is
engaged by chain 118. The side of this element 156 opposite from
the hexagon side 157 is simply a smooth rounded portion 159.
Surrounding the two hexagon portions 152 and 157 is a clutch member
161, the internal surface of which is shaped so as to positively
engage the surfaces 152 and 157 for rotation therewith. For
example, the internal surface of element 161 may be a polygon of
either six sides or 12 sides. In the position as shown, which
represents the normal position of the clutch, the clutch member 161
engages both 152 and 157 and hence transfers torque from element
152 to the element 157. Thus, in this position, any rotation of the
wheel 127 will cause rotation of the element 156 and hence also of
the chain 118, the sprocket 115a, the spur gear 115, the drive
wheel 110 and hence the belts 25 and 26. A spring 153 normally
urges the element 161 into this drive position.
To disengage the clutch the element 164, which is visible above and
below the element 161 in FIG. 11, is moved to the right (as shown
in FIG. 11). In this manner the element 164 acts as a pressure
plate against an annular flange 162 on the element 161 thereby
urging this element 161 to the right against the action of spring
163 until no part of the element 161 surrounds the part 157 of the
element 156. In this condition the wheel 27 may be rotated without
causing movement of the belts 25 and 26.
This pressure plate 164, which is shown also in FIG. 10, is
connected by connecting plate 165 to the element 130. Between the
plates 164 and 130, there is provided an eccentric cam element 166.
By turning this cam element 166, the larger part thereof acts
against the plate 164, which of course would be resiliently mounted
relative to plate 165 and 130, urging plate 164 towards the wheel
27. As indicated above, this causes disengagement of the hexagon
portion 157 from the hexagon portion 152, and hence disengagement
of the belts 25 and 26 from the wheel 27. Referring to FIGS. 9 and
10, there may be provided a square shaft 167 passing from the plate
70 mounted on the arm rest 11 (see FIG. 5) down to and through the
cam 166. In this manner, the operator can simply turn the lever 168
(see FIGS. 5 and 9) and thereby turn the cam 66 to operate the
clutch. The shaft 167 passes slidably through the cam 166 which in
turn is vertically fixed relative to the plates 130 and 164. In
this manner, the cam 166 moves upwardly and downwardly with the
plate 130, the square shaft 167 sliding vertically relative to the
cam 166 during this vertical movement.
Although the invention has been described in considerable detail
with respect to a preferred embodiment thereof, it should be
apparent that the invention is capable of numerous modifications
and variations apparent to those skilled in the art without
departing from the spirit and scope of the invention.
* * * * *