Wheel chair abstract
A conventional wheel chair is modified by the provision of a safety
system for automatically actuating the brakes of the wheel chair
and lifting the foot rests when the weight of the patient is lifted
from the seat. An overcenter spring arrangement is used to bias
the brake mechanism into the braking position and is pulled over
center by a solenoid actuated by a switch under the seat. The actuation
of the brake mechanism is communicated to the foot pedals by a connection
cable which pulls a latch pin to release the spring biased foot
pedal into the retracted position.
Wheel chair claims
We claim:
1. A wheel chair comprising a frame, a seat bottom mounted on the
frame for receiving and supporting the buttocks of a patient in
a seated position, a seat back mounted on the frame against which
the back of the seated patient can rest, ground wheels attached
to the frame for wheeled movement of the frame and seated patient
across the ground, a pair of foot rest elements located in a foot
rest position forwardly of and downwardly from the seat bottom,
each for receiving a respective foot of the seated patient to maintain
the foot carried above the ground during the wheeled movement, and
actuation means responsive to movement of the patient from the seated
position to effect movement of the foot rest elements from the foot
rest position to a retracted position allowing the patient to place
the feet on the ground forwardly and downwardly of the seat bottom
and to step forwardly therefrom without engaging the foot rest elements,
wherein said actuation means includes a switch actuable by the lifting
of the weight of the patient from the seat bottom.
2. The wheel chair according to claim 1 wherein the foot rest elements
are each mounted on a respective one of a pair of forwardly extending
posts with each foot rest element being pivotal about a longitudinal
axis of the post from the foot rest position extending horizontally
from the post inwardly to the retracted position extending vertically
upwardly from the post.
3. The wheel chair according to claim 2 including spring means
biasing the foot rest element to the retracted position and latch
means for latching the foot rest element in the foot rest position,
said actuation means being arranged to release said latch means.
4. The wheel chair according to claim 3 wherein said actuation
means includes a pair of cables each extending to a respective one
of the foot rest elements, each cable being movable longitudinally
to actuate release of said latch means.
5. The wheel chair according to claim 1 including a pair of brakes,
each actuable to cause braking of a respective one of said ground
wheels, said actuation means being arranged to actuate the brakes.
6. The wheel chair according to claim 5 wherein the actuation means
includes a cable extending from the brake to a respective one of
the foot rest elements for actuating movement of the foot rest element
from the foot rest position to the retracted position.
7. The wheel chair according to claim 1 wherein the actuation means
includes a pair of solenoids, each for effecting said movement of
a respective one of said footrests, and a battery mounted on the
frame and arranged to provide power to the solenoids, said switch
being arranged for actuating said solenoids.
8. The wheel chair according to claim 7 wherein the frame includes
a pair of horizontal rails each extending along a respective side
of the frame, a pair of brackets each mounted on a respective one
of the rails and a pair of brakes each pivotally mounted on a respective
one of the brackets for movement into engagement with a respective
one of the wheels and wherein each of the solenoids is mounted on
the respective mounting bracket carried on the respective rail and
extending longitudinally of the respective rail for actuating the
respective brake.
9. The wheel chair according to claim 8 wherein the actuation means
includes a cable extending from each brake to a respective one of
the foot rest elements.
10. The wheel chair according to claim 8 wherein the brake is movable
between the engagement position and a release position and wherein
there is provided spring means shaped and arranged to move from
a first orientation in which the spring means biases the brake means
into the release position to a second orientation in which the spring
means biases the brake means into the engagement position, the solenoid
being arranged to pull the brake means such that the spring means
moves from the first orientation into the second orientation.
11. A wheel chair comprising a frame, a seat bottom mounted on
the frame for receiving and supporting the buttocks of a patient
in a seated position, a seat back mounted on the frame against which
the back of the seated patient can rest, ground wheels attached
to the frame for wheeled movement of the frame and seated patient
across the ground, a pair of foot rest elements located in a foot
rest position forwardly of and downwardly from the seat bottom,
each for receiving a respective foot of the seated patient to maintain
the foot carried above the ground during the wheeled movement, a
pair of brake members each movable from a brake release position
to a brake engagement position for engagement with a respective
one of the wheels and a pair of actuating linkages each extending
from a respective one of the brake members to a respective one of
the foot rest elements, each actuating linkage being arranged to
actuate movement of the foot rest element, in response to movement
of the brake member to the brake engagement position, from the foot
rest position to a retracted position allowing the patient to place
the feet on the ground forwardly and downwardly under the seat bottom
and to step forwardly therefrom without engaging the foot rest elements.
12. The wheel chair according to claim 11 wherein the foot rest
elements are each mounted on a respective one of a pair of forwardly
extending posts with each foot rest element being pivotal about
a longitudinal axis of the post from the foot rest position extending
horizontally from the post inwardly to the retracted position extending
vertically upwardly from the post.
13. The wheel chair according to claim 11 including spring means
biasing the foot rest element to the retracted position and latch
means for latching the foot rest element in the foot rest position,
said actuating linkage being arranged to release said latch.
Wheel chair description
This invention relates to a wheel chair and a kit of parts for
attachment to a wheel chair for improving the safety of the patient.
The majority of wheel chair rated accidents originate from the failure
to lock the brakes and/or to raise the pedals to transfer in or
out of the wheel chair. Such user negligence due to forgetfulness
or preoccupation on the part of the user. Serious falls occur regularly
due to the wheel chair rolling away at the time of transfer or due
to the client stepping onto unraised foot pedals at the time of
transfer. Such falls result in various injuries ranging from abrasions
and skin tears to fractures and serious joint dislocations.
Health care workers have traditionally used an intervention approach
to protect vulnerable clients from accidents during wheelchair transfers.
They set up the supervision of vulnerable clients or they might
use lap restraints to prevent the user from the transferring on
their own. This compromises client independence and raises legal
issues. In some cases the patient can even be placed in a gerichair
further restraining and limiting independence.
A number of proposals have been made previously in patents and
patent applications for devices which allow the brakes to be automatically
applied when the patient rises from the seat. However these devices
are not widely available in practice presumably due to their complexity
or inefficiency.
SUMMARY OF THE INVENTION
It is one object of the present invention, therefore, to provide
an improved safety device for attachment to a wheel chair.
According to the invention, therefore, there is provided a wheel
chair comprising a frame, a seat bottom mounted on the frame for
receiving and supporting the buttocks of a patient in a seated position,
a seat back mounted on the frame against which the back of the seated
patient can rest, ground wheels attached to the frame for wheeled
movement of the frame and seated patient across the ground, a pair
of foot rest elements located in a foot rest position forwardly
of and downwardly from the seat bottom, each for receiving a respective
foot of the seated patient to maintain the foot carried above the
ground during the wheeled movement, and actuation means responsive
to movement of the patient from the seated position to move the
foot rest elements from the foot rest position to a retracted position
allowing the patient to place the feet on the ground forwardly and
downwardly of the seat bottom and to step forwardly therefrom without
engaging the foot rest elements.
According to the second aspect of the invention there is provided
a wheelchair comprising a frame, a seat bottom mounted on the frame
for receiving and supporting the buttocks of a patient in a seated
position, a seat back mounted on the frame against which the back
of the seated patient can rest, ground wheels attached to the frame
for wheeled movement of the frame and seated patient across the
ground, the ground wheels including a pair of large rear wheels
and a pair of smaller front castor wheels, a pair of brake members
each mounted on a bracket at a side of the frame for pivotal movement
from a brake release position to a brake engagement position in
which the brake member is in engagement with a respective one of
the large rear wheels, an attachment kit for automatic actuation
of the brake member comprising a biasing spring connecting between
the brake member and the frame and arranged to apply a braking force
to the brake member into the engagement position, a solenoid mounted
on the frame adjacent the brake member and arranged to cause said
spring member to move the brake member into the brake engagement
position, a battery mounted on the frame for providing power to
the solenoid and switch means responsive to movement of the patient
from the seated position to actuate said solenoid.
According to the third aspect of the invention there is provided
a wheel chair comprising frame, a seat bottom mounted on the frame
for receiving and supporting the buttocks of a patient in a seated
position, a seat back mounted on the frame against which the back
of the seated patient can rest, ground wheels attached to the frame
for wheeled movement of the frame and seated patient across the
ground, a pair of foot rest elements located in a foot rest position
forwardly of and downwardly from the seat bottom, each for receiving
a respective foot of the seated patient to maintain the foot carried
above the ground during the wheeled movement, a pair of brake members
each movable from a brake release position to a brake engagement
position for engagement with a respective one of the wheels and
a pair of cables each extending from a respective one of the brake
members to a respective one of the foot rest elements, the cable
being arranged to actuate movement of the foot rest element in response
to movement of the brake member to the brake engagement position
from the foot rest position to a retracted position allowing the
patient to place the feet on the ground forwardly and downwardly
under the seat bottom and to step forwardly therefrom without engaging
the foot rest elements.
The preferred approach to the safety problem is therefore a preventative
approach. It should safeguard the user yet promote independence.
It should protect client autonomy while minimizing staff time required
for supervision. It should make up for the deficiencies of the user.
The electric safety device of the present invention has been developed
to meet the above described needs. Utilizing a pressure sensitive
switch located beneath the seat of the wheel chair, device guarantees
that the wheel chair will automatically lock and the pedals will
raise as soon as the user's weight lifts off the seat of the chair.
The mechanism required is relatively simple and without complexity.
Moreover it can be developed as a kit to modify any wheel chair
already in use. The concept can also be incorporated into the design
of a new wheel chair. The designer can incorporate an on/off switch
which can be used by the caregiver if they wish to turn the mechanism
off. Batteries providing electrical power to the solenoid can be
readily charged as required.
One embodiment of the invention will now be described in conjunction
with the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a wheel chair of a conventional
design including the safety attachment of the present invention.
FIG. 2 is a view along lines 2--2 of FIG. 1.
FIG. 3 is a cross sectional view along lines 3--3 of FIG. 1.
FIG. 4 is an enlarged view showing the brake assembly of FIG. 1
in the braking position.
DETAILED DESCRIPTION
A conventional wheel chair comprises a frame generally indicated
at 10 including two side frame elements 11 only one of which is
visible in FIG. 1 but it will be appreciated that the wheel chair
of FIG. 1 is symmetrical about a centre line and the opposed side
is identical to the side visible in FIG. 1. The side frame elements
includes a loop frame structure standing in a vertical plane including
a top horizontal rail 12, a first intermediate horizontal rail 13,
a second intermediate horizontal rail 14 and a bottom rail 15. The
horizontal rails are connected by a rear vertical post 16 and a
front vertical post 17. The bottom rail 15 extends rearwardly beyond
the vertical post 16 into a rearwardly projecting stub portion 18.
The bottom rail 15 further includes a raised front section 19 which
extends upwardly and over the front wheel or the wheel chair. The
two side frames are interconnected by an X-frame structure 20 including
cross braces 21 and 22 connected together at a pivot coupling 23.
Each of the cross braces is connected at its lower end to a respective
one of the bottom rails 15 and at its upper end to a respective
one of the intermediate rails 13. A pivot coupling portion of those
rails allows the X-frame to pivot as the two side frame portions
11 move together in a folding action.
A seat bottom 22 of a flexible fabric material extends between
the side rails 13 and thus moves slightly upwardly and downwardly
in response to the weight of the patient resting thereon in a seated
position. A seat back 24 extends upwardly and rearwardly and is
again formed from a flexible fabric material mounted on a pair of
posts each arranged at a respective side frame portion. A large
rear wheel 25 is mounted on a hub 26 carried at the rear of the
post 16. A front castor wheel 27 is mounted on a castor support
28 carried in a sleeve 29 mounted on the post 17. A foot rest element
is generally indicated at 30 and is mounted on the front of the
post 17. Each foot rest element includes a support post 31 extending
upwardly parallel to the post 17. At the upper end the post 31 is
inclined forwardly to a horizontal pivot pin 32 to which is attached
a depending support leg 33 extending downwardly and forwardly from
the post 17. The leg 33 is slightly cranked so the first portion
is vertical while a second portion toward the ground is inclined
forwardly and downwardly. At a base of the leg is mounted a stub
shaft 34 which projects forwardly and slightly upwardly at a position
just above the ground surface. The stub shaft 34 carries a sleeve
35 which is pivotal about a longitudinal axis of the stub shaft.
On the sleeve is mounted a foot pad plate 36 which is welded to
a lower inside edge of the sleeve so as to project horizontally
inwardly in a foot receiving position shown on the left of FIG.
2. A stop member (not shown) prevents rotation of the sleeve 35
in a clockwise direction beyond the position shown in FIG. 2 so
that the plate 36 is held generally horizontally to receive the
foot of the patient at a position downwardly and forwardly of the
front edge of the seat bottom to hold that foot during transportation
of the patient across the ground. In the deployed foot receiving
position, each of the plates 36 lies horizontally across the front
area of the chair with the inside edges of the plates closely adjacent.
A brake mechanism 40 comprises a bracket 41 carried on the rail
14 and projecting downwardly therefrom. On the bracket 41 is carried
a pivotal brake member 42 which includes a vertical plate lying
parallel to the bracket 41 and pivotal relative thereto on a pivot
pin 43. At the bottom end of the plate forming the brake member
is provided a horizontal wheel engaging portion 44. In the release
position shown in FIG. 1, the horizontal plate 44 is spaced from
the periphery of the tire. In the actuated position shown in FIG.
4, the plate 44 is moved rearwardly into engagement with the periphery
of the tire indicated at 45. The brake member 42 is pivoted to its
release position and brake engaging position by a lever 46 having
a handle 47 projecting upwardly from the rail 14. The lever 46 is
mounted on the bracket 41 while pivotal movement about a pin 48.
A low end of the lever projects downwardly from the bracket 41 and
is connected to an actuating link 49 connected at one end by a pin
50 to the lever 46 and at the other end by a pin 51 to the brake
member 42. Thus forward and rearward movement of the lever 46 causes
movement of the brake member 42 to the braking position and release
position respectively.
The above construction of a wheel chair is conventional and other
designs are available with which the present invention can be used.
The design above described provides only one example of a wheel
chair in which the present invention can be used.
The safety attachment for the wheel chair comprises an automatic
brake actuating mechanism generally indicated at 60, a seat switch
61 and a foot pedal automatic release mechanism generally indicated
at 62.
The automatic safety system is powered by a battery 63 mounted
at a suitable location on the frame and supported thereby. The main
control switch 64 operable by the caregiver is mounted on the frame
at a suitable location generally behind the patient. The seat switch
61 comprises a pad 65 which is attached to the flexible seat bottom
22 and acts to operate a lever 66 carry on a switch body 67 attached
to one of the cross braces 21. The lever 66 is arranged so that,
when the weight of the patient is removed from the seat bottom,
the lever rises and actuates the switch 67 to communicate power
from the battery 63 to one of the pair of solenoids 68.
On each side of the chair is mounted a brake actuating mechanism
60 and this comprises the solenoid 68 which is mounted upon a plate
shaped bracket 69 suitably attached by collars 70 to the horizontal
rail 14. The solenoid is arranged longitudinally of the rail and
below the rail so that the application of power to the solenoid
pulls an actuating rod 71 of the solenoid. The end of the rod 71
includes a collar 72 which engages around a rear end of the pin
51 of the brake mechanism.
The safety system further includes a spring 74 arranged to apply
braking force to the brake mechanism. The spring 74 is mounted on
a curved arm 75 which connects to the handle 46 at a position above
the pivot pin 48. The lower end of the spring 74 is attached by
a loop 76 to the frame at a suitable location thereon. The shape
of the arm is such that the spring goes over centre as it passes
from the release position shown in FIG. 1 to the brake engaging
position shown in FIG. 4. Thus the spring acts to bias the brake
device into both of the positions and simply pulled over centre
by the actuation of the solenoid. The force of the solenoid is therefore
not required to apply the braking action but is simply a trigger
to pull the brake device over centre so that the force for the brake
device is applied by the spring 74.
The safety device further includes for each side of the chair a
respective one of the pedal release mechanism 62. The pedal release
mechanism comprises a spring 80 which is added to the post 34 and
is coiled around the post so as to apply to the plate 36 a force
biasing that plate into the raised or retracted position shown at
the right hand side of FIG. 2. The normal or release position of
the foot pedals is therefore the retracted position as shown on
the right hand side of FIG. 2. The foot pedals are however latched
in the foot receiving position shown on the left hand side of FIG.
2 by a pin 81 which engages through a hole in the top surface of
the collar 35 and into the post 34 so as to lock the collar 35 in
the foot receiving position. The pin 81 is carried in a sleeve 82
and is spring biased by a spring 83 into the latching position.
The pin however can slide in the sleeve 82 against the bias of the
spring pulled by a cable 84 attached to an upper end 85 of the pin
81. The cable is of the sheath type having an exposed lower end
attached to the end of the pin. A sheath 86 of the cable is clamped
between a lower clamp 87 on the leg 33 and the second clamp 88 on
the post 31. The sheath is thus held in position and the cable can
slide along the fixed sheath when pulled at its upper end. The upper
end of the cable is indicated at 89 and is attached as best shown
in FIG. 4 to a hole 90 in the brake device 42. Thus the operation
of the brake device by the solenoid and spring arrangement also
causes the cable to be pulled upwardly relative to the sleeve 82
that is pulling the pin from the latching position and automatically
releasing the foot pedal into the retracted position.
In operation, therefore, with the patient seated, the brake can
be manually removed to the release position and the foot pedals
moved downwardly into the foot receiving position again by manual
operation by the caregiver. The foot pedals are latched in position
by the latch pins and the brake devices are held in the release
position by the over centre spring. However when the patient lifts
their weight from the chair for transfer either under their own
volition or under the control of the caregiver, the brake mechanism
is immediately applied and the foot pedals are raised. The patient
when lifting their weight from the chair places their feet behind
the foot pedals on the ground and the lifting of the foot pedals
immediately allows access for the patient to step forwardly without
any danger of engaging the foot pedals which can cause tripping
or falling.
The design of the device including the simple solenoid and over
centre spring arrangement together with the cable connection to
the foot pedals allows simple retrofit onto existing wheel chairs
of a simple and relatively inexpensive kit.
Since various modifications can be made in my invention as hereinabove
described, and many apparently widely different embodiments of same
made within the spirit and scope of the claims without departing
from such spirit and scope, it is intended that all matter contained
in the accompanying specification shall be interpreted as illustrative
only and not in a limiting sense. |