U.S. patent application number 09/910737 was filed with the patent office on 2001-11-15 for wheelchair automatic anti-rollback assembly.
This patent application is currently assigned to 210 INNOVATIONS LLC. Invention is credited to Marquis, James A., Ritchie, James K..
Application Number | 20010040354 09/910737 |
Document ID | / |
Family ID | 21834449 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040354 |
Kind Code |
A1 |
Ritchie, James K. ; et
al. |
November 15, 2001 |
Wheelchair automatic anti-rollback assembly
Abstract
An anti-rollback assembly adapted or adaptable for use in
combination with a wheelchair. The anti-rollback assembly includes
a one-way brake assembly automatically immobilizing the wheelchair
against rearward movement when the occupant attempts to rise from
or sit in a seat member of the wheelchair, yet at the same time
does not prevent the wheelchair from moving in a forward direction.
Conversely, when the occupant is fully seated in the seat member,
the one-way brake assembly is disengaged so that the wheelchair can
move freely in forward or rearward directions. The assembly can be
retrofitted onto existing wheelchairs, and is adjustable to fit
various size wheelchairs.
Inventors: |
Ritchie, James K.;
(Waterford, CT) ; Marquis, James A.; (Springfield,
MA) |
Correspondence
Address: |
Pillsbury Winthrop LLP
Intellectual Property Group
1600 Tysons Boulevard
McLean
VA
22102
US
|
Assignee: |
210 INNOVATIONS LLC
|
Family ID: |
21834449 |
Appl. No.: |
09/910737 |
Filed: |
July 24, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09910737 |
Jul 24, 2001 |
|
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|
09578488 |
May 26, 2000 |
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Current U.S.
Class: |
280/304.1 ;
188/2F |
Current CPC
Class: |
A61G 5/10 20130101; A61B
5/1115 20130101; B62B 5/0409 20130101; A61G 5/1086 20161101; A61G
5/14 20130101; A61G 5/1054 20161101 |
Class at
Publication: |
280/304.1 ;
188/2.00F |
International
Class: |
B62J 001/00; B62H
001/00 |
Claims
What is claimed is:
1. A wheelchair comprising: a frame structure; a rear drive wheel
assembly rotatably supported by said frame structure; a front wheel
assembly rotatably supported by said frame structure; a seat member
supported by said frame structure and constructed and oriented to
accommodate an occupant; a one-way brake assembly including a
one-way brake member, said one-way brake-assembly being movable
between a non-activated position in which said one-way brake member
is positioned to permit said rear drive assembly to rotate-in
forward and rearward directions to enable said wheelchair to move
freely in both the forward and rearward directions, and a
non-activated position in which said one-way brake member is
positioned to prevent rotation of said rear drive wheel assembly in
the rearward direction so as to prevent movement of said wheelchair
in the rearward direction while continuing to permit rotation of
said rear drive wheel assembly in said forward direction for
forward movement of said wheelchair; a biasing member operatively
associated with said one-way brake assembly to bias said one-way
brake assembly towards the activated position; and a brake
releasing assembly operatively associated with said one-way brake
assembly and said biasing member, said brake releasing assembly
being movable in response to said wheelchair being occupied to
overcome the bias of said biasing member so as to move said one-way
brake assembly from the activated position to the non-activated
position, thus enabling said wheelchair to freely move in both the
forward and rearward directions.
2. A wheelchair according to claim 1, wherein said rear drive wheel
assembly includes first and second drive wheels, wherein said
one-way brake member is disposed in surface engagement with said
first and second drive wheels to prevent rearward movement of said
wheelchair when said brake assembly is in the activated position,
and wherein said one-way brake member is spaced from said first and
second drive wheels when said brake assembly is in the
non-activated position to permit said first and second drive wheels
to rotate freely and thereby enable said wheelchair to move in the
forward and rearward directions.
3. A wheelchair comprising: a frame structure; a rear drive wheel
assembly comprising first and second drive wheels rotatably
supported by said frame structure; a front wheel assembly
comprising first and second front wheels rotatably supported by
said frame structure; a seat member supported by said frame
structure and constructed and oriented to accommodate an occupant;
first and second one-way brake assemblies, each of which includes a
one-way brake member, said first and second one-way brake
assemblies being movable between a non-activated position in which
said one-way brake members are positioned to permit said rear drive
wheel assembly to rotate in forward and rearward directions to
enable said wheelchair to move freely in both the forward and
rearward directions, and a non-activated position in which said
one-way brake members are positioned to prevent rotation of said
rear drive wheel assembly in the rearward direction so as to
prevent movement of said wheelchair in the rearward direction while
continuing to permit rotation of said rear drive wheel assembly in
the forward direction for forward movement of said wheelchair; a
biasing member operatively associated with at least one of said
one-way brake assemblies to bias said at least one of said one-way
brake assemblies towards the activated position; and a brake
releasing assembly operatively associated with said biasing member
and said at least one of said one-way brake assemblies, said brake
releasing assembly being movable in response to said wheelchair
being occupied to overcome the bias of said biasing member so as to
move said at least one of said one-way brake assemblies from the
activated position to the-non-activated position, thus enabling
said wheelchair to freely move in both the forward and rearward
directions.
4. A wheelchair according to claim 3, wherein said first and second
one-way brake members are respectively disposed in surface
engagement with said first and second drive wheels to prevent
rearward movement of said wheelchair when said brake assembly is in
the activated position, and wherein said first and second one-way
brake members are respectively spaced from said first and second
drive wheels when said brake assembly is in the non-activated
position to permit said first and second drive wheels to rotate
freely and thereby enable said wheelchair to move in the forward
and rearward directions.
5. A wheelchair according to-claim 3, wherein said biasing member
is operatively associated with both of said first and second
one-way brake assemblies to bias said first and second one-way
brake assemblies toward the activated position, and further wherein
said brake releasing assembly is operatively associated with said
biasing member and said first and second one-way brake assemblies,
said brake releasing assembly being movable in response to said
wheelchair being occupied to overcome the bias of said biasing
member so as to move said first and second one-way brake assemblies
from the activated position to the non-activated position, thus
enabling said wheelchair to freely move in both the forward and
rearward directions.
6. A wheelchair according to claim 5, wherein said seat member is
movable from an upper position to a lower position in response to
the weight of the occupant, and wherein said seat member is
cooperatively associated with said brake releasing assembly to move
said first and second one-way brake assemblies from the activated
position to the non-activated position in response to downward
movement of said seat member from the upper position to the lower
position.
7. A wheelchair according to claim 6, wherein said seat member is
biased towards the upper position by said biasing member.
8. A wheelchair according to claim 7, wherein said one-way brake
members of said first and second one-way brake assemblies follow
respective arcuate paths between the activated position and the
non-activated position, the arcuate paths of the first and second
one-way brake assemblies intersect rotational paths of said first
and second drive wheels, respectively.
9. A wheelchair according to claim 3, wherein said biasing member
is a torsion spring.
10. A wheelchair according to claim 3, wherein said wheelchair
further comprises an ambulation monitor operatively associated with
said one-way brake assembly or said brake releasing assembly to
activate an alarm when the wheelchair occupant attempts to rise
from said seat member.
11. An anti-rollback assembly comprising: first and second one-way
brake assemblies, each of said brake assemblies including a
mounting assembly mountable on a frame structure of a wheelchair
and a one-way brake member associated with and supported by said
mounting assembly, each of said one-way brake members having a
distal end portion movable along an arcuate path relative to said
associated mounting assembly; a brake releasing assembly
operatively associated with said first and second one-way brake
assemblies so as to move said one-way brake members of said one-way
brake assemblies along the arcuate path.
12. An anti-rollback assembly according to claim 11, wherein each
of said first and second one-way brake assemblies includes a
rotatable brake-member supporting member supporting said one-way
brake member in such a manner that rotation of said brake-member
supporting member about a longitudinal axis thereof moves said
one-way brake member alone the arcuate path.
13. An anti-rollback assembly according to claim 12, wherein said
brake releasing assembly comprises an actuating lever and
adjustable length connecting plates operatively connecting said
first and second one-way brake assemblies to said actuating lever.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to wheelchairs and
more particularly to an anti-rollback assembly that operatively
associates with a wheelchair to prevent the wheelchair from rolling
backwards and away from its occupant as the occupant attempts to
mount or dismount the wheelchair, yet permits the wheelchair in an
unoccupied state to be moved in a forward direction.
[0003] The anti-rollback assembly of the present invention is
especially suitable for wheelchairs of invalids, the cognitively
impaired, the elderly, and sufferers of physically and mentally
disabling diseases such as Alzheimer's.
[0004] 2. Description of the Related Art
[0005] Almost all wheelchairs possess a parking brake in one form
or another which, when actuated, maintains the wheelchair in a
stationary position by preventing one or both of the large drive
wheels of the wheelchair from rotating about a common central axis.
Perhaps the most crucial periods for the wheelchair to remain
stationary are when a person attempts to sit down in and occupy the
wheelchair and when the occupant attempts to stand up from and
vacate the wheelchair. The natural motion of a person performing
these acts imparts a force in the rearward direction on the
wheelchair, which, without the benefit of an actuated parking
brake, causes the wheelchair to move backwards and away from the
person.
[0006] As a consequence of the mental and physical infirmities
suffered by many wheelchair occupants, especially patients
suffering from Alzheimer's disease and other mental frailties,
occupants often forget to actuate manually-operated parking brakes
prior to attempting to rise from the wheelchair, or neglect to
inspect the parking brake to ensure it is engaged in a locked
position prior to attempting to sit down into the wheelchair.
Failure to engage the manually-operated parking brake in its locked
position presents a serious hazard of injury to both the occupant
and his or her caretaker, since the wheelchair is unimpeded from
rolling back and away from the occupant as the occupant attempts to
rise from or sit down in the wheelchair.
[0007] To address the shortcomings of manually-operated parking
brakes, several different automatically-operated locking brake
assemblies have been proposed. U.S. Pat. No. 5,203,433 sets forth a
discussion of some conventional automatic locking brake assemblies.
Each of the conventional assemblies mentioned in U.S. Pat. No.
5,203,433 is characterized by the provision of a locking member
that, unless manually disengaged, prevents or at least
substantially obstructs both the forward or rearward movement of
the wheelchair with which the assembly is associated when the
wheelchair is unoccupied.
[0008] However, one of the most important functions served by an
automatic wheelchair brake is that it not only prevent the
wheelchair from rolling backwards and away from its occupant as the
occupant mounts or dismounts the wheelchair, but that the brake
also not substantially obstruct the forward motion of the
wheelchair when unoccupied so that the unoccupied wheelchair can be
easily maneuvered to a desirable location for use or temporary
storage.
[0009] A long-felt need therefore exists to provide an
automatically-operated anti-rollback assembly for a wheelchair that
biases a braking mechanism into an activated position when the
wheelchair is unoccupied to prevent the wheelchair from rolling
back when it is mounted or dismounted in normal operation, yet,
while in the activated position, permits the forward motion of the
unoccupied wheelchair.
SUMMARY OF THE INVENTION
[0010] It is, therefore, an object of the present invention to
provide an anti-rollback assembly that solves the aforementioned
problems associated with the related art as well as other problems
and addresses the long-felt need outlined above.
[0011] It is another object of the present invention to provide an
automatic anti-rollback assembly which is reliable in operation,
easy to use, and economical to manufacture.
[0012] A further object of the present invention is to provide an
automatic anti-rollback assembly that can be easily and
inexpensively retrofitted to existing wheelchairs.
[0013] It is another object of the present invention to provide an
automatic anti-rollback assembly that, when operatively associated
with a wheelchair, permits the unoccupied wheelchair to freely roll
in a forward direction, yet impedes only the rearward motion of the
wheelchair, so that the unoccupied wheelchair can be used, for
example, as a walker.
[0014] Still another object of the present invention is the
provision of a wheelchair having an automatic anti-rollback
assembly with an ambulation monitor which activates an alarm when
the wheelchair occupant attempts to vacate the wheelchair.
[0015] In accordance with the principles of the present invention,
these and other objects are attained by the provision of an
automatic anti-rollback assembly that is adapted or adaptable for
use in combination with a wheelchair. The automatic anti-rollback
assembly generally comprises a one-way brake assembly supportable
on a frame structure of a wheelchair, biasing member, and a brake
releasing assembly. The one-way brake assembly includes a one-way
brake member (or brake arm). When used in combination with a
wheelchair, the one-way brake assembly is movable between a
non-activated position in which the one-way brake member is
positioned to permit the rear drive wheel assembly to rotate in
forward and rearward directions to enable the wheelchair to move
freely in both the forward and rearward directions, and a
non-activated position in which the one-way brake member is
positioned to prevent rotation of the rear drive wheel assembly in
the rearward direction so as to prevent movement of the wheelchair
in the rearward direction, yet continues to permit rotation of the
rear drive wheel assembly in the forward direction for forward
movement of the wheelchair. The biasing member serves to impart a
biasing force to urge the one-way brake assembly towards the
activated position. The brake releasing assembly is operatively
associated with the one-way brake assembly and the biasing member,
and is movable in response to the wheelchair being occupied to
overcome the biasing force of the biasing member so as to move the
one-way brake assembly from the activated position to the
non-activated position, thereby enabling the wheelchair to freely
move in both the forward and rearward directions unencumbered by
the one-way brake member.
[0016] In accordance with the present invention, the occupant of
the wheelchair is not required to set a conventional parking brake.
Instead, the wheelchair is automatically immobilized against
backward movement by the anti-rollback device when the occupant is
attempting to rise from or sit himself in the seat member. In
addition, when the occupant is fully seated in the seat member, the
anti-rollback device is disengaged, i.e., the one-way brake
assembly is moved into a non-activated position, so that the
wheelchair can be freely moved forward or backwards unencumbered by
the one-way brake member.
[0017] These and other objects, features, and advantages of the
present invention will become apparent from the following detailed
description when taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings illustrate an embodiment of the
present invention. In such drawings:
[0019] FIG. 1 is a perspective rear view of a wheelchair including
an anti-rollback assembly in accordance with a preferred embodiment
of the present invention, in which the range of movement of the
anti-rollback assembly between non-activated and activated
positions is depicted by arrows;
[0020] FIGS. 2A and 2B are side elevational views of the wheelchair
of FIG. 1 in occupied and unoccupied states, respectively;
[0021] FIG. 3 is an exploded view of mounting and brake releasing
assemblies of the anti-rollback assembly of FIG. 1;
[0022] FIG. 4 is a perspective view of a bracket and brake arm
supporting member of the mounting assembly of FIGS. 1 and 3;
[0023] FIG. 5 is a rear view of the bracket of the mounting
assembly depicting a biasing member;
[0024] FIG. 6 is a side view of an ambulation monitor according to
one embodiment of the present invention; and
[0025] FIG. 7 is an exploded view of the ambulation monitor of FIG.
6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] A detailed description of a conventional wheelchair
structure will be discussed hereinbelow for the purposes of
assisting in the detailed description of the anti-rollback assembly
of the present invention and explaining the manner in which the
anti-rollback assembly is operatively supported on a wheelchair. It
is understood, however, the present invention is not restricted to
the illustrated wheelchair or the construction and arrangement of
the individual components of the illustrated wheelchair.
[0027] Referring now to the drawings, there is shown in FIGS. 1,
2A, and 2B a wheelchair generally is designated by reference
numeral 10. The wheelchair 10 includes a frame structure 12
comprising a pair of opposing side frames 14a and 14b laterally
spaced from and substantially parallel with one another. The
opposing side 20 frames 14a and 14b have respective front upright
members 16a and 16b and respective rear upright members 18a and
18b. In the illustrated embodiment, the front upright member 16a
and the rear upright member 18a of the side frame 14a 25 include
longitudinal axes oriented substantially vertical, and are
interconnected with crossbars 19a and 20a. The front upright member
16b and the rear upright member 18b of the other side frame 14b are
arranged and interconnected in a similar manner with crossbars 19b
and 20b. Handles 22a and 22b are fitted onto upper ends
(unnumbered) of the rear upright members 18a and 18b, respectively.
Arm rests 24a and 24b are secured to upper surfaces of the
crossbars 19a and 19b, respectively.
[0028] The wheelchair 10 further includes a flexible seat member 26
extending between the opposing side frames 14a and 14b and arranged
in a substantially horizontal orientation so as to permit an
occupant to sit thereon. A flexible back support member 28 extends
between the rear upright members 18a and 18b and, together with the
seat member 26, define a seating area (unnumbered) for supporting
the wheelchair occupant.
[0029] As shown in FIG. 1., the wheelchair 10 further includes rear
drive wheel assemblies comprising two large rear drive wheels 30a
and 30b which are manually rotatable by the occupant to rotate
about hubs 32a and 32b, respectively. The hubs 32a and 32b are
respectively attached to the rear upright members 18a and 18b with
axle bolts (unnumbered) and each include a plurality of spokes (not
shown) extending therefrom to interconnect the hubs 32a and 32b to
their respective drive wheels 30a and 30b. Front wheel assemblies
comprise small wheels 34a and 34b swivably connected to the front
upright members 16a and 16b, respectively, to facilitate turning of
the wheelchair 10.
[0030] Although not shown, it is understood that in accordance with
the present invention, the wheelchair 10 can include additional
components, such as footrests. It is further understood that in
accordance with the present invention the wheelchair can omit one
or more of the components discussed above and illustrated in the
drawings, so long as the wheelchair is characterized as being
capable of operatively supporting the anti-rollback feature of the
present invention.
[0031] One embodiment of the automatic anti-rollback assembly of
the present invention, which is generally designated by reference
numeral 40, will now be described with greater specificity
hereinbelow.
[0032] Referring to FIGS. 3 and 4, the illustrated automatic
anti-rollback assembly 40 includes two mounting assemblies. For
explanatory purposes, only one of the two mounting assemblies,
which is generally designated by reference numeral 42, will be
described below.
[0033] The mounting assembly 42 includes a mounting bracket 44 with
a discontinuous circular clamping end 46, which accommodates the
rear upright member 18a. Nut-bolt combinations 48 and 50 serve to
secure the mounting bracket 44 to the rear upright member 18a.
Reinforcement spacers 52 may be used in combination with the
nut-bolt combinations 48 and 50 to prevent bowing of the bolts. The
reinforcement spacers 52 can be made of, for example, nylon or
other plastics. As shown in FIGS. 1, 2A, and 2B, the clamping end
46 of the mounting bracket 44 is positioned immediately above the
axle bolt associated with hub 32a.
[0034] The mounting assembly 42 further includes a movable
brake-arm supporting member 54 (also referred to as a brake-member
supporting member or pivotable collar), which is substantially
configured as a clevis yoke. In the illustrated embodiment, the
brake-arm supporting member 54 is rotatable about its longitudinal
axis between first and second positions. Opposing sides of the
mounting bracket 44 define aligned apertures, one of which is
designated by reference numeral 56 in FIG. 4. The apertures 56 are
sized to receive a shaft 58 co-axially extending from and integral
with the pivotable collar 54. The shaft 58 is secured to the
mounting bracket 44 with, for example, a lock cap 60. As shown in
FIG. 5, a torsion spring 62 is accommodated in the mounting bracket
44 and connected to the shaft 58 of the pivotable collar 54 via pin
63 to urge the pivotable collar 54 into its first position.
[0035] The opposite end (unnumbered) of the pivotable collar 54
defines a slot 66 diametrically positioned and axially extending a
certain depth into pivotable collar 54. A first S bore 68 is
diametrically defined within the pivotable collar 54, and arranged
orthogonally relative to the slot 66 to intersect the slot 66.
Second and third bores 70 and 72 are each diametrically disposed,
arranged orthogonally relative to each other to intersect each
other, and are interposed between the slot 66 and the shaft 58. The
functions of the slot 66 and the first, second, and third bores 68,
70, and 72 will be described below.
[0036] Still referring to FIG. 3, the automatic anti-rollback
assembly 40 further includes a brake releasing assembly, which is
generally designated by reference numeral 74.
[0037] The brake releasing assembly 74 includes a substantially
L-shaped actuator lever 76, adjustor plate 78, and connector plates
80. For explanatory purposes, the connector plate 80 and the side
of the adjustor plate 78 operatively associated with mounting
assembly 42 will be described below.
[0038] The actuator lever 76 is cantilevered at a central portion
(unnumbered) of the adjustor plate 78. The end (unnumbered) of the
adjustor plate 78 defines an exposed lateral port 82, which
receives a portion of the connector plate 80. The upper region of
the adjustor plate 78 has an elongated slot 84 defined therethrough
in communication with the lateral port 82. (As shown in FIG. 3, the
slots 84 are located on each side of the central portion of the
adjustor plate 78.) A nut-washer combination 86 engages a first
aperture 88 of the connector plate 80 and the elongated slot 84 to
thereby secure the adjustor plate 78 to the connector plate 80. The
end of the connector plate 80 opposite to the first aperture 88
defines a second aperture 90.
[0039] As shown in FIGS. 2A and 2B, when the brake releasing
assembly 74 is connected to the mounting assembly 42, the brake
releasing assembly 74 is positioned immediately underneath the seat
member 26. The connection of the brake releasing assembly 74 to the
mounting assembly 42 will now be described with reference to FIG.
3.
[0040] The slot 66 of the pivotable collar 54 receives the end of
the adjustor plate 78 containing the second aperture 90 so that the
first bore 68 and the second aperture 90 are aligned. A
quick-release pin 92 is inserted through the aligned first bore 68
and second aperture 90 to secure the brake releasing assembly 74 to
the mounting assembly 42. The provision of the quick-release pin 92
or similar connecting device facilitates the quick and easy
separation and removal of the brake releasing assembly 74. When the
wheelchair 10 is of the collapsible variety, the frames 14a and 14b
and associated wheels on either side of the seat member 26 can
thereby be folded together for convenient stowage. The provision of
a quick-releasing mechanism to facilitate the ability of the
wheelchair 10 to be collapsed and stored represents one of the many
advantages of the present invention.
[0041] Another of the advantages of the illustrated embodiment
rests in the configuration of the elongated slots 84 of the
adjustor plate 78, which provides for an adjustable positional
relationship with the first aperture 88 of connector plate 80. This
feature makes the illustrated anti-rollback assembly 40 adaptable
and retrofittable to wheelchairs of various widths. Although not
shown, it is noted that the elongated slots 84 can be replaced
with, for example, a series of spaced apertures.
[0042] The anti-rollback assembly 40 also includes a brake member
(or brake arm) 94, a proximal end portion 96 of which is received
in the second bore 70 of the pivotable collar 54 and secured
thereto with a set screw 98 (FIG. 3). (The brake member 94 and
mounting assembly 42 collectively form a one-way brake assembly in
this embodiment.) As respectively shown in FIGS. 2A and 2B, a
distal end portion 99 of the brake arm 94 either is spaced from a
rear region of the drive wheel 30a (when the wheelchair 10 is
occupied) or rests on the drive wheel 30a (when the wheelchair 10
is unoccupied or the occupant attempts to rise from or sit down
into the wheelchair 10). As is believed evident from this
description, the positional relationship-of the brake arm 94 to the
pivotable collar 54 can be adjusted (by loosening set screw 98) to
make the brake arm 94 adaptable and retrofittable to wheelchairs of
various drive wheel sizes.
[0043] The operational movement of the anti-rollback assembly 40
will be described below with reference to FIGS. 1, 2A, 2B, and
3.
[0044] In its unoccupied state, the torsion spring 62 imparts a
biasing force to urge the brake-arm supporting member 54 towards
the first position, which in turn urges the seat member 26 towards
its upper position and the distal end portion 99 of the brake arm
94 into the activated position. In the activated position, the
distal end portion 99 of the brake arm 94 prevents the first drive
wheel 30a from rotating about a central axis thereof in a rearward
direction, yet does not prevent the first drive wheel 30a from
rotating about the central axis thereof in a forward direction.
[0045] When a patient attempts to rest into the seating area of the
wheelchair 10, the weight of the patient imparts a downward force
on the seat member 26, which causes the seat member 26 to flex,
bend, slide, or otherwise move in a downward direction to its lower
position. The downward movement of the seat member 26 translates
the downward force to the actuator lever 76, thereby pivoting the
actuator lever 76 downward as indicated by the arrow in FIG. 2A. As
the actuator lever 76 pivots, the adjustor plate 78 is rotated
about its longitudinal axis to translate a corresponding rotational
movement to pivotable collar 54. As the collar 54 rotates about its
axis, the brake arm 94 operatively associated therewith is pivoted
about the region of its proximal end portion 96 accommodated in the
second bore 70 so that the distal end portion 99 is moved from the
activated position to a non-activated position. In the
non-activated position, the distal end portion 99 is radially
spaced from the drive wheel 30a and, hence, does not interfere with
manual operation (including both forward and rearward motion) of
the wheelchair 10.
[0046] Conversely, when an occupant of the wheelchair 10 attempts
to rise from the seating area, the torsion spring 62 imparts a
biasing force to urge the brake-arm supporting member 54 towards
the first position, which in turn urges the seat member 26 towards
its upper position and the distal end portion 99 of the brake arm
94 to move in a downward manner along an arcuate path (as shown by
the arrow in FIG. 2B) into the activated position.
[0047] In the illustrated embodiment, the arcuate path that the
distal end portion 99 of the brake arm 94 follows between the
activated and non-activated positions intersects the circumference
of the drive wheel 30a. Consequently, the amount of frictional
force applied to the brake arm 94 by the drive-wheel 30a is
proportional to the rearward force applied to the wheelchair 10.
Stated differently, when the wheelchair 10 is moved rearwardly,
frictional force between the drive wheel 30a and the brake arm 94
causes the distal end portion 99 of the brake arm 94 to move in a
generally radially inward direction towards the hub 32a, which
further presses the distal end portion 99 into the drive wheel 30a.
Consequently, continued rearward motion of the wheelchair 10 has a
corresponding immobilizing effect on the drive wheel 30a of the
wheelchair 10.
[0048] Accordingly, even though the occupant of the wheelchair 10
may neglect to set a conventional parking brake (not shown), the
chair 10 is automatically immobilized against backward movement by
the anti-rollback device when the occupant is attempting to rise
from or seat himself in the seat member 26.
[0049] Referring now to FIGS. 6 and 7, according to another
embodiment of the present invention the wheelchair is equipped with
an ambulation monitor, generally designated by reference numeral
100, for activating an alarm when the occupant of the wheelchair 10
attempts to rise from the seat member 26.
[0050] As shown in FIG. 7, the ambulation monitor includes a
housing structure 102, which houses a horn 104, an on/off switch
106 and a switch jack 108 electrically connected to the horn 104,
and an energy source 110, e.g., a battery, electrically connected
to the on/off switch 106. The housing structure 102 is supported on
the mounting bracket 44 with a mounting bracket 112, a mounting
bracket clamp knob 114, and screws 116a and 116b.
[0051] Referring now to FIG. 6, a connector wire 120 electrically
connects the switch jack 108 to a cam actuator switch 122. A cam
124 is cooperatively associated with the pivotable collar 54 by
providing the cam 124 with an eccentrically disposed aperture 126
through which a portion of the pivotable collar 54 is disposed.
Accordingly, when the occupant begins to rise from the seat member
26, the pivotable collar 54 is rotated about its longitudinal axis
as described above. The cam 124, by virtue of its cooperative
association with the pivotable collar 54, rotates to actuate the
switch 122, thereby activating the horn 104 to alert staff of the
occurrence.
[0052] In its broadest aspects, several variations and
modifications to the above-discussed anti-rollback assembly can be
implemented without departing from the scope of the present
invention. For example, the anti-rollback assembly 40 may include a
separate biasing member or members, such as springs, to urge the
seat member into its upper position independent of or in
conjunction with the torsion spring 62. Also, although in the
illustrated embodiment each of the drive wheels 30a and 30b and a
one-way brake assembly (that is, a mounting assembly and brake arm)
associated therewith, it is understood that the anti-rollback
assembly 40 may include only one mounting assembly 42 and brake arm
94, in which case, for example, a pivotable bar (not shown) may
interconnect the brake releasing assembly 74 with the side frame
14b not associated with the mounting assembly 42 and brake arm 94.
Where the anti-rollback assembly includes one-way brake assemblies
respectively associated with each of the drive wheels 30a and 30b
(as shown in FIGS. 1, 2A, and 2B), a second torsion spring (not
shown) may be accommodated in the mounting bracket associated with
the second drive wheel 30b; alternatively, the anti-rollback
assembly 40 may include only a single torsion spring, since the
pivotable collar 54 associated with the first drive wheel 30a
rotates in unison with the pivotable collar associated with the
second drive wheel 30b due to the interconnection provided by the
brake releasing assembly 74.
[0053] The one-way brake assemblies may respectively engage
portions of the rear drive wheel assemblies at positions other than
the rear drive wheel. For example, although not shown, the
assemblies could include ratchet and pawl wheel assemblies to
accomplish the anti-rollback function of the present invention.
[0054] These and other modifications to the assembly, when viewed
with reference to this disclosure, are within the purview of those
skilled in the art.
[0055] If desired, the automatic anti-rollback assembly 40 of the
present invention may be used in conjunction with conventional
supplemental braking devices well known in the art, including, for
example, a manually-operated parking brake to immobilize the
wheelchair from forward or rearward movement when occupied.
[0056] This application claims priority of provisional patent
application No. 60/039,485, the complete disclosure of which is
incorporated herein by reference.
[0057] The foregoing detailed description of the preferred
embodiments of the invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise embodiments disclosed. The
embodiments were chosen and described in order to best explain the
principles of the invention and its practical application, thereby
enabling others skilled in the art to understand the invention.
While the invention has been described in connection with what is
presently considered to be the most practical and preferred
embodiments, it is understood that the invention is not limited to
the disclosed embodiments, but, on the contrary, is intended to
cover various modifications and equivalent arrangements included
within the spirit and scope of the appended claims.
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