Note: Descriptions are shown in the official language in which they were submitted.
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REVERSIBLE SEAT FOR FRONT WHEEL DRIVE AND
REAR WHEEL DRIVE POWER WHEELCHAIR HAVING
INFINITE ANGULAR ADJUSTMENT
Background of the Invention
This invention relates to wheelchairs, and more
particularly to power wheelchairs, in which seat adjustment
is desired. Additionally, the wheelchair may be converted
from a front wheel drive arrangement to a rear wheel drive
assembly without extensive changeover of structural elements
of the seat.
Commonly owned U.S. Patent No. 5,575,348 is
directed to a power wheelchair of the general type under
consideration. The details of that patent are hereby
incorporated by reference. It shows and describes a power
wheelchair having an H-shaped frame in which the intersecting
corner of the seat and seat back is mounted for rotation
about a pin and a link is disposed beneath the seat and frame
adjacent a forward portion of the seat to adjust the seat
angle. A bracket extends from the frame and includes spaced
openings so that the link is secured to a selected one of the
openings. By connecting the link to a different opening, the
seat angle is varied.
Moreover, the 5,575,348 patent discloses a
conventional power wheelchair structure in which enlarged
diameter wheels are motor driven and located toward a rear
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portion of the frame. Small diameter front wheels are
typically caster-mounted for rotation about respective
vertical axes in response to the drive of the rear wheels
controlled by the wheelchair user via a motor controller such
as a joystick.
It is becoming increasingly popular to provide a
front wheel, or mid-frame, drive arrangement where the
enlarged diameter drive wheels are located closer to the
front of the chair, i.e., at a mid-frame location or more
closely adjacent the front edge of the seat. For purposes of
brevity, the front wheel and mid-frame drive arrangements
will be referred to as front wheel drive wheelchairs in this
specification, although it will be understood that the
description applies to both unless particularly noted
otherwise. Different design and engineering considerations
are embodied in the front and rear wheel drive
configurations. Nevertheless, it is desired that as many
common structural components be used in the rear wheel drive
and front wheel drive assemblies to simplify manufacturing
and assembly, and consequently reduce cost. Thus, even
though not all components of these two types of chairs are
identical, it is preferred to use as many of the same
components as possible.
Weight distribution affects the overall performance
of the wheelchair. Tracking, steering, wear, etc., are all
related to the weight distribution so that enhanced
performance is closely linked to the weight distribution and
the ability to easily adjust it For example, if too much
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weight is distributed on the front wheels, steering becomes
more difficult, particularly on softer surfaces such as
carpeting.
As will also be appreciated, occupants of power
wheelchairs are seated in the wheelchairs for extended
periods of time. It is desirable, therefore, to provide a
wide range of adjustment for the seat, either fore or aft, as
well as angular adjustment without unnecessary complication.
In this manner, the basic wheelchair structure can
accommodate the needs of different individuals.
Summary of the Invention
The present invention contemplates a new and
improved wheelchair that overcomes all of the above
referenced problems and others and provides a simple,
economical structure that provides ease of adjustment and
conversion.
According to a more limited aspect of the
invention, the wheelchair includes a frame having a
longitudinal frame portion that extends fore and aft and a
lateral frame member that extends generally perpendicular
thereto. Front and rear wheels are mounted to the frame and
a seat is mounted to the frame through a seat mount assembly.
The seat mount assembly allows for selective fore and aft
adjustment of the seat relative to the frame.
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According to another aspect of the invention, the
seat mount assembly includes first and second seat support
members secured to the frame and the seat, respectively. The
seat support members are connected together by elongated
slots and pins so that an angular adjustment can be achieved.
According to still another aspect of the invention,
the seat mount assembly is adjusted fore and aft via a
channel. In a preferred arrangement, the channel is
integrally formed on the frame'
A principal advantage of the invention is the
ability to provide increased adjustment for the wheelchair
user.
Still another advantage of the invention resides in
the angular adjustment that is available.
Yet another advantage resides in the fore and aft
adjustment of the seat relative to the frame.
A still further advantage of the invention resides
in the ability to reverse the position of the seat relative
to the frame to accommodate front wheel drive or rear wheel
drive units.
Still other advantages and benefits of the
invention will become apparent to those skilled in the art
upon a reading and understanding of the following detailed
description.
srief Description of the Drawinqs
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The invention may take physical form in certain
parts and arrangements of parts, a preferred embodiment of
which will be described below. The accompanying
illustrations are not intended to limit the scope of the
5invention, but rather show the preferred embodiment only.
Particularly, :
Figure 1 is a perspective view of a power
wheelchair of the type to which the subject invention may
pertain.
10Figure 2 is an exploded perspective view of a
conventional frame used in these types of wheelchairs.
Figure 3 is an exploded perspective view of the
components of the reversible, adjustable seat support
assembly of the present invention.
15Figure 4 is an elevational view of a rear wheel
drive power wheelchair with the seat at a 0~ inclination.
Figure 5 is an elevational view similar to Figure
3 but showing the seat at a 10~ angle.
Figure 6 shows an elevational view of a front wheel
20drive arrangement where the seat has been reversed from the
position of Figures 4 and 5, and the seat is disposed at a 0~
orientation.
Figure 7 is an elevational view similar to that of
Figure 5 with the seat at an angle of approximately 10~.
25Figure 8 is a cross sectional view taken generally
along the lines 8-8 in Figure 4.
Detailed Description of the Preferred Embodiment
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Referring now to the drawings which illustrate the
preferred embodiment of the invention only and are not
intended to limit the invention, the Figures show a
wheelchair, preferably a power wheelchair A. For
5convenience, the drawings occasionally identify the
components by a suffix "a" or "b" which is intended to
represent that the wheelchair includes a pair of the
described component, it being understood that description of
one is applicable to the other unless noted to the contrary.
10Generally, the wheelchair A includes a frame 10 to
which enlarged diameter wheels 12, also referred to as drive
wheels, are operatively connected. Small diameter or driven
wheels 14a, 14b are also operatively mounted to the frame.
A seat 16 comprised of a seat portion 18 and a seat back 20
15is mounted on the frame. The prior art power wheelchair of
Figure 1 has a basic seat assembly, although it will be
understood that the seat can be customized with special
cushions, bolsters, pads, etc., to meet the needs of the
individual user.
20First and second motors 22a, 22b, preferably one
associated with each drive wheel, are mounted on the frame
and operatively connected to the drive wheels through a gear
box or other conventional structure. The motors are
typically electrically operated and, thus, the wheelchair
25carries an on-board source of power such as batteries 24. A
control, such as joy stick control 26, is mounted on one of
the arm rests 28 so that power is selectively provided to the
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left or right motor to selectively drive the wheels 12 in a
forward or reverse direction. Details of a battery operated,
joy stick controlled power wheelchair are generally known in
the art so that further discussion herein is deemed
unnecessary to a full and complete understanding of the
present invention. As will be appreciated, powered rotation
of the drive wheels steers the wheelchair since the driven
wheels 14 are rotatably connected to the frame via caster
assemblies 30. Again, details of the caster assemblies are
well known in the art so that further discussion is not
warranted.
With continued reference to Figure 1, and
additional reference to Figure 2, the preferred frame 10 is
shown in greater detail. It is preferably an H-shaped
configuration formed of rigid metal tubing having a hollow
rectangular cross section. First and second longitudinal
frame members 40a, 40b extend fore and aft in the general
direction of the drive and driven wheels. A cross or
interconnecting frame member 42 is disposed substantially
perpendicular and rigidly connected at opposite ends to the
longitudinal frame members, for instance by welding or the
like. Each longitudinal frame member has a first end 44 and
a second end 46. In a preferred arrangement, the first ends
44 terminate in a generally cylindrical housing that receives
the caster assembly of the small diameter driven wheels 14a.
A shock absorber assembly 48 (Figure 2) is preferably mounted
adjacent the second ends 46 of the longitudinal frame members
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while the drive wheels are secured through a linkage assembly
(unnumbered). Again, details of the structure shown in
Figure 2 are set forth in greater detail in commonly owned
U.S. Patent No. 5,575,348 so that familiarity with that
structure is presumed and further description herein is
deemed unnecessary.
Attention is additionally directed to Figure 3
which shows an exploded view of the seat support assembly, as
well as Figures 4 and 5 which schematically illustrate a rear
wheel drive version of a power wheelchair of the present
invention. Where possible, like reference numerals will
refer to like parts and the features of the present invention
will be identified by new reference numerals. In the rear
wheel drive version, the enlarged diameter drive wheels 12
are more closely positioned adjacent the seat back 20 than
the front of the seat portion 18. Similarly, the small
diameter driven wheels 14 are more closely located adjacent
the front of the seat 18 than to the seat back 20.
The seat 16 includes rigid seat frame portions 60,
62 that are typically disposed beneath the cushion or
upholstery portions of the wheelchair seat. As shown, seat
frame member 60 is a rigid structure adapted to receive the
seat cushion 18 while the angle bracket 62 is fixedly secured
to the seat frame portion 60 in a generally perpendicular
relation, and thus forms a part of the seat back 20. A seat
support assembly 64 (Figure 4) interconnects the seat
assembly 16 to the frame. It includes a first or upper seat
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support member 66 that is secured to an underside of the seat
frame 60. In accordance with the preferred embodiment, the
seat support member 66 includes a pair of elongated slots 68,
70 generally disposed at opposite ends thereof. As will be
S more fully developed below, the elongated slots allow for
desired angular adjustment of the seat relative to the frame.
Additionally, the seat support assembly includes a
second or lower seat support member 76. It is adapted for
connection to the frame, particularly the longitudinal
members 40a, 40b in a manner to be described further below.
Moreover, the second seat support member has a generally
triangular conformation that is mounted so that the higher
end is disposed toward the first end 44 of the frame. Since
the frame is preferably disposed at an angle, the triangular
conformation provides that an upper surface of the second
seat support is disposed in a generally horizontal plane.
Openings 78 disposed at opposite ends of a second
seat support member are adapted to receive a pin-type
fastener, such as a nut and bolt 80, that passes through the
respective openings 68, 70 of the first seat support member.
By selectively loosening and tightening the fastener 80, the
angular location of the seat may be adjusted. For example,
as shown in Figure 4, the fastener 80 is disposed adjacent an
upper region of elongated opening 68, while fastener 82 is
disposed adjacent a lower region of the elongated opening 70.
This attitude of the seat support assembly places the seat at
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a oo orientation relative to the ground surface, i.e., an
upright seat position.
When comparing the angle of the seat in Figure 4
with that of Figure 5, it is evident that the seat has been
adjusted to define an approximately 10~ angle between the
seat 18 and the ground surface. This changeover is achieved
by loosening the fasteners 80, 82 and situating the fastener
80 adjacent the lower region of the elongated opening 68 and
moving the fastener 82 adjacent the upper region of the
elongated opening 70.
As will be appreciated, although only the oo and
10~ angular positions of the seat are illustrated, an
infinite number of angular positions may be adopted
therebetween by altering the positions of the fasteners 80 in
the respective elongated openings 68, 70. The use of a pair
of elongated openings provides for incremental adjustment
over the maximum range.
Figures 6 and 7 illustrate a front wheel drive
wheelchair. Substantially, the same components are used in
this front wheel drive version as were used in the rear wheel
drive arrangement of Figures 4 and 5. The seat support
assembly uses the identical two seat support members 66 and
76, although the seat support members are reversed relative
to one another. That is, the seat support member 66 remains
secured to the seat frame member 60 in the same relationship
so that the seat and seat support member 66 are merely
reversed (i.e., rotated 180~) relative to the seat support
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member 76 and the frame. As will be appreciated, to achieve
the oo angle illustrated in Figure 6, the fastener 80 is
disposed adjacent the lower region of the elongated opening
70 while fastener 82 is disposed adjacent the upper region of
the elongated opening 68. A 10~ adjustment of the seat angle
can be accomplished in the front wheel drive version, again,
by loosening the fasteners, re-orienting the seat support
members (without disassembly), and tightening the fasteners
at the desired new position. Thus, as represented in Figure
7, a 10~ angle is defined between the seat 18 and the ground
surface by positioning the fastener 82 adjacent the lower end
of the elongated opening 68 while the fastener 80 is disposed
adjacent the upper end of elongated opening 70. Of course,
it will be appreciated, that the arrangement of the elongated
openings and pins can be reversed, i.e., elongated openings
provided on a seat support member secured to the frame while
the fasteners 80, 82 could be provided on the seat support
member secured to the seat, without substantially altering
the seat adjustment function.
For ease of adjustment of the seat angle, the
fasteners 80, 82 are preferably received through the first
and second seat support members 66, 76 and secured in
elongated bar 84 (Figure 3). Particularly, each bar 84
includes threaded openings 86, 88 at opposite ends that allow
the user to merely tighten the fasteners from a region easily
accessible from outside of the wheelchair and without concern
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for holding a nut or the like in place at a region that would
be difficult to access underneath the seat.
As will also be understood by comparing Figures 4
and 5 with Figures 6 and 7, the seat support assembly, and
thus the seat, has been moved rearwardly along the
longitudinal frame 40. This fore and aft adjustment is a key
concept of the present invention since it allows easy fore
and aft adjustment without disassembling the entire seat.
This is an important consideration where the weight to be
carried by the caster wheels is to be altered. Moreover, and
although the seat 16 is mounted in a reverse relationship,
the identical components can be used for the rear wheel drive
and front wheel drive assemblies.
Additional reference to Figure 8 illustrates a
cross-sectional view of one of the longitudinal frame members
40, again, it being understood that the structure of the
other longitudinal frame member is the same unless noted
otherwise. The longitudinal frame member is a generally
hollow rectangular structure having side walls 90, 92 and
generally perpendicular upper and lower walls 94, 96. The
hollow rectangular tube construction provides the desired
rigidity and strength required for the power wheelchair
frame. In addition, channel 100 is defined by inverted L-
shaped arms 102, 104. In the preferred embodiment, the
channel is integrally formed on an upper surface of the wall
94 of the longitudinal frame member. It will be appreciated,
however, that the channel could also be defined by a separate
components secured to the longitudinal frame members. In any
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event, the channel 100 has an opening 106 defined between the
arms that preferably faces upwardly. The opening receives at
least one fastener 108, preferably a fastener at each end,
extending from the second seat support member 76. For
example, the fastener is a threaded nut and bolt assembly
where the nut 110 is locked against rotation in the channel
100 while bolt 108 can be selectively tightened from above.
When fully tightened, the fore to aft location of the seat
support assembly is fixed relative to the frame. By merely
loosening these fasteners, the entire seat support assembly
can be moved fore and aft along the longitudinal frame
members, i.e., to various locations over the wheels 12, 14 as
desired. Again, as briefly indicated above, this allows for
alteration of the weight carried by the different wheels.
The invention has been described with reference to
the preferred embodiment. Obviously, modifications and
alterations will occur to others upon a reading and
understanding of this specification. It is intended to
include all such modifications and alterations insofar as
they come within the scope of the appended claims or the
equivalents thereof.
