Wheel chair abstract
An electrically powered wheel-chair for indoor and outdoor use
comprising a pair of rear main wheels, which are non-pivotably connected
with the frame-work of the chair, at least one of said wheels being
driven by an electric motor. A steering wheel being rotatably connected
with the frame-work of the wheel-chair and positioned in front of
the main wheels, said steering wheel being asymmetrically located
on one side of a longitudinal axis through the middle of the chair.
A support wheel being positioned on the other side of said longitudinal
axis relative to the steering wheel at such a level above a flat
and horizontal ground surface that it will not touch this surface
when the steering wheel directed straight ahead. The diameter of
the support wheel is less than that of the steering wheel and the
distance from the fore-most point of the steering wheel to a transverse
axis through the centers of the main wheels is greater than the
corresponding distance for the support wheel. To provide good stability
the electric batteries are located in a case thus designed that
the common center of gravity of the batteries will be located on
the same side of the longitudinal axis of the chair as the steering
wheel. The frame-work is moreover equipped with two auxiliary support
wheels on either side of the chair and rearwards the main wheels.
Wheel chair claims
We claim:
1. An electrically powered wheel-chair for stable and maneuverable
indoor and outdoor use, comprising in combination:
a pair of rear main wheels, which are rigidly connected with the
frame of the chair, at least one of said main wheels being driven
by an electric traction motor,
a front steering wheel, which is rotatably connected with the frame
and located on one side of a longitudinal axis through the middle
of the chair,
a support wheel with less diameter than the steering wheel, said
support wheel being connected with the frame and located on the
other side of said longitudinal axis relative to said steering wheel
at such a level that it will not touch a horizontal and even support
surface when the steering wheel is directed straight ahead, whereby
the fore-most point of the steering wheel is located ahead of the
fore-most point of the support wheel, a portion of the frame positioned
between the main wheels being designed in the form of a case, adapted
to contain batteries, the common center of gravity of which will
be located on the same side of the longitudinal axis of the chair
as the steering wheel.
2. An electrically powered wheel-chair for indoor and outdoor use,
comprising:
a pair of rear main wheels, which are rigidly connected with the
frame of the chair, at least one of said main wheels being driven
by an electric traction motor,
a front steering wheel, which is rotatably connected with the frame
and located on one side of a longitudinal axis through the middle
of the chair,
a support wheel with less diameter than the steering wheel, said
support wheel being connected with the frame and located on the
other side of said longitudinal axis relative to said steering wheel
at such a level that it will not touch a horizontal and even support
surface when the steering wheel is directed straight ahead, whereby
the fore-most point of the steering wheel is located ahead of the
fore-most point of the support wheel, a portion of the frame positioned
between the main wheels being designed in the form of a case, adapted
to contain batteries, the common center of gravity of which will
be located on same side of the longitudinal axis of the chair as
the steering wheel, and that a seat of the chair is pivotally supported
by a tubular column resting on the bottom of the battery case on
a surface thereof, the center of said column being located on the
other side of said longitudinal axis relative to the center of gravity
of the batteries.
3. A wheel-chair as claimed in claim 2, characterized in that the
support wheel is non-pivotally connected with the frame.
4. A wheel-chair as claimed in claim 2, characterized in that the
tubular column is telescopically arranged and supports a rectangular
seat-frame, one corner of which is rigidly secured to the column.
5. A wheel-chair as claimed in claim 4, characterized in that the
seat is rotatable between a straight forward position substantially
in parallel with the longitudinal axis of the chair and an outwards
turned position, about 90.degree. from said straight forward position,
the rotational axis of the seat coinciding with the center axis
of the tubular column, and the column being fastened to one corner
of the seat frame located in the rear section thereof, whereby the
front section of the seat will be positioned substantially outside
one of the main wheels, when the seat is in its outward turned position
thereby facilitating taking and leaving of the seat.
6. A wheel-chair as claimed in claim 2, characterized in that the
frame is provided with two auxiliary support wheels on either side
of the chair and rearwards of the main wheels.
7. A wheel-chair as claimed in claim 2, characterized in that the
location of the resultant center of gravity of the chair and a person
sitting therein is selected to lie close to and in front of a transverse
axis through the centers of the main wheels, provided that the occupant
has taken up normal steering position and is driving on substantially
horizontal ground.
Wheel chair description
The present invention relates to an electrically powered wheel-chair
for indoor and outdoor use comprising, a pair of rear main wheels
rigidly connected with the chassis of the chair, at least one of
said mainwheels being driven by an electric traction motor, a front
steering wheel, which is rotatably connected with the chassis.
The conventional wheel-chair for indoor use has one large driving
wheel on either side of the seat, and one or two smaller wheels
disposed in front of or behind the driving wheels usually in the
form of castor wheels with vertical pivots. Such wheel-chairs cannot
be used outdoors, except on a flat and hard surface. To be suitable
for indoor use, the dimensions of a chair must be kept within very
narrow limits, and its steering wheels must be arranged to minimize
its turning radius.
There are motor-driven wheel-chairs to be used both indoors and
outdoors, where the front wheels are rigidly connected with the
chassis, and the rear wheels are assembled to one unit, which is
pivotable relative to the chassis. This type of wheel-chair, which
is called "PERMOBIL SUPERIOR" (registered trade mark),
is disclosed in Swedish Pat. Specification No. 306,805 and is intended
primarily for severely handicapped persons which are incapable of
driving or steering a wheel-chair manually. In the Permobil Superior
these functions are accomplished by electric servo motors, which
are controlled by impulses initiated by the invalid by means, for
example, of a suction- and blowing-nozzle.
Further, there are three-wheeled wheel-chairs, in which the steering
wheel is disposed in front of or behind a person sitting in the
chair, or between his feet. Where the steering wheel is disposed
at the rear end, the vehicle will have to be made extremely elongate
in order to attain satisfactory stability properties. If the steering
wheel is disposed between the feet of the occupant, the chair cannot
climb kerb stones and unevennesses on the ground surface without
great danger for turning over. Several such three-wheeled chairs
are intended primarily for outdoor use, since the design generaly
requires so much space that the chair does not satisfy the requirements
of compactness, and thus will be unwieldy to handle indoors. Other
wheelchairs with the steering wheel disposed between the feet of
the occupant are adapted primarily for indoor use but, as mentioned
above, they will be instable in outdoor use.
Further, there are four-wheeled single vehicles for outdoor use
with extremely advantageous properties for cross-country driving.
These chairs are neither suitable to use indoors, since the design
is primarily adapted to satisfy extremely great demands on stability
and thus is not sufficiently compact nor has this chair sufficiently
small turning radius to be used indoors.
Thus, up till now the above-described conventional type of wheel-chair
for indoor use has been the only facility available for less seriously
disabled people and it has as such been an extremely valuable implement.
This conventional indoor chair, however, has many drawbacks causing
inconveniences to the operator. Thus, it can be diffcult for a disabled
person to get into and out of the chair without any assistance,
since the seat is fixed and the seat direction coincides with the
direction of the main wheels. Therefore, the chair must either be
held on or its brakes must be applied before the operator can take
or leave the chair, in order to prevent it from beginning to move.
Further, an occupant may encounter difficulties in coming sufficiently
close to a work bench or the like with an underlying case or cupboard.
This will of course aggravate the possibilities for an invalid to
work in normal office and factory premises and the difficulties
for the integration of disabled persons in a normal working life
will thus be unnecessary increased.
The main object of the present invention is to provide a compact
wheel-chair which is easy to handle, has small turning radius and
good stability properties. Further, the chair should be easy to
take and leave, and it should also be possible for the disabled
person to discharge his calls of nature from the chair without the
necessity of leaving it.
A further object of the invention is to provide a wheel-chair which
has good stability and maneuverability properties so that it can
be driven outdoors on hilly ground, for instance on sloping greens
or paths, thereby reducing the need for two chairs, viz. one specific
indoor chair and one for outdoor use, to one single chair for both
applications of use.
These objects are realised in a wheel-chair according to the present
invention substantially by the fact that the steering wheel is located
on one side of a longitudinal axis through the middle of the chair,
and that a support wheel with less diameter than the steering wheel
is connected with the chassis and located on the other side of said
longitudinal axis relative to said steering wheel at such a level
that it will not touch a horizontal and even support surface, and
that the distance from the foremost point of the steering wheel
to a transverse axis through the centres of the main wheels is greater
than the corresponding distance for the support wheel.
The supporting wheel is preferably non-pivotally connected with
the chassis, which in one embodiment of the invention is designed
in the form of a case for batteries the common centre of gravity
of which is disposed on the same side of the longitudinal axis through
the center of the chair as the steering wheel, thereby increasing
the stability of the vehicle.
In order to realize the object to facilitate the taking and leaving
of the chair, the seat of the chair is rotatably supported on the
bottom of the battery case on a surface, which is positioned on
the opposite side of the longitudinal axis through the middle of
the chair relative to that of the common centre of gravity of the
batteries. The seat support can suitably be in the form of a telescoping
tubular column, which is associated with a rectangular frame for
the seat and is rigidly secured to one corner of this frame. When
the occupant is to leave the chair, the seat is preferably rotated
from an angular position substantially in parallel with the longitudinal
axis of the chair to an outwards turned position, about 90.degree.
from the straight forward position. The rotational axis of the seat
coincides with the centre axis of the tubular column, and the column
is fastened to one corner of the seat frame located in/the rear
section and towards the leaving side of the chair whereby the front
section of the seat will be positioned substantially outside one
rear wheel when the seat is in its outwards turned position thereby
facilitating the disabled person to take and leave the chair.
In order to improve the rearward stability of the chair, the chassis
is provided on either side thereof and rearwards to the main wheels
with two auxiliary supporting wheels. These supporting wheels are
of particular importance when the chair is climbing up a hill or
when the occupant is leaning heavily backwards.
One embodiment of the invention will now be described more in detail
with reference to the accompanying drawings, in which:
FIG. 1 is a top-plan view of a wheel-chair according to the invention
with the seat removed;
FIG. 2 is a side-elevational view of the chair shown in FIG. 1;
FIG. 3 is a perspective view of the chair, with the seat shown
in an exploded view; and
FIG. 4 is a perspective view of the steering gear as well as the
driving and braking mechanism for one of the main wheels.
As illustrated in FIGS. 1 and 2, the wheel-chair of the invention
comprises a pair of rear wheels 1, which are non-pivotally mounted
on the chassis 2. Further, a steering wheel 3 is pivotally connected
with a frame 4 of the chassis, which frame carries a steering column
5 for the steering wheel. Rotational movement of the steering wheel
is effected by means of a control lever 6 the angular movement of
which is converted by a bevel gearing 7 into a corresponding rotational
movement of the steering wheel. This arrangement is particularly
suitable since it provides a greater deflection of the wheel than
tie rods, which in addition, require considerably greater space.
The chassis further carries a support wheel 8, which is disposed
on the opposite side of a longitudinal axis through the centre of
the chair relative to the steering wheel. The support wheel is disposed
at a certain height above the ground surface, which means that it
will not be in touch with the ground when driving the chair straight
ahead on a flat and horisontal surface. However, when turning the
chair to the side opposite to that of the support wheel, i.e., when
turning right in the embodiment shown, the chair will tilt outwards
in the curve, and the support wheel 8 will contact the ground and
prevent the chair from turning over. The support wheel will also
touch the ground if, for instance, the chair is moved straight ahead
down a slope or the like. Two further support wheels 9 are carried
at the rear section of the chassis and these wheels do not touch
a horizontal ground plane either, when the chair is unloaded. When
driving up-hill or if the occupant should lean heavily backwards,
these rear supporting wheels will, however, touch the ground, thereby
preventing the chair from turning over backwards.
The resultant centre of gravity for the chair and a person sitting
therein with the seat in its straight forward position will lie
on a vertical line positioned immediately in front of a transverse
axis through the centres of the main wheels. This arrangement enables
the extremely compact construction of the chair, which, however,
has called for the necessity of providing it with the rear support
wheels. The chassis further carries a foot-plate 10, which is hinged
to the front frame 4. In the embodiment shown. the support wheel
8 is disposed behind the outer edge of the foot-plate 10, whereby
the taking and leaving of the seat will be considerably facilitated.
This arrangement will also permit enough room for the feet. In addition,
the foot-plate is positioned beside the steering wheel 3, whereby
the sitting direction for a person in normal driving attitute will
form a certain angle relative to the longitudinal axis of the chair.
The size of the steering wheel 3 has been selected to facilitate
outdoor operation.
Further, the portion of the chassis 2 located between the main
wheels 1 is designed as a case for batteries 11, which are asymmetrically
disposed in this case in such a way that their common centre of
gravity will be positioned on the same side of the longitudinal
axis through the centre of the chair as the steering wheel. This
arrangement permits the batteries to form a counterbalancee to a
person sitting in the seat, which is carried by a telescoping tubular
column 12 the lower end of which is supported on the bottom of the
battery case. The seat arrangement is shown in FIG. 3 and comprises
a lower frame 13, which is welded to a collar 14 on the upper tube
of the column. An upper frame 15 is connected at the front section
of the seat with the lower seat frame 13, whereas its rear section
is connected with a shock absorber 16, which is housed within the
tubular column and which is surrounded by a coil spring. The upper
seat frame 15 is further provided with longitudinally extending
channel bars 17 in which guide rods 19 secured to the seat 18 are
displaceable and can be locked in any desired position. This arrangement
provides for an adjustable position of the seat in the sitting direction,
which makes it possible to change the resultant centre of gravity
in a way either to reduce the loading of the steering wheel to facilitate
maneuvering, or to increase this loading in order to improve the
steering function, for instance when driving up-hill. Since the
channel bars 17 and the guide bars 19 displaceable therein are positioned
above the centre of rotation of the seat, which can be displaced
in the sitting direction even in the outwards turned position of
the seat, thereby enabling the operator to sit with his legs in
a normal attitude beneath a table. The seat can, of course, be locked
in any desired position by some form of locking device, for instance
by means of a screw on a handle, which can be set in two different
positions. The seat with the frame assembly and the upper tubular
column are rotatable in the lower and outer tubular column connected
with the bottom of the battery case from one inwards turned position
shown in FIG. 3 to an outwards turned position about 90 degrees
from the first position, in which the front section of the seat
will be positioned outside the left main wheel, whereby the occupant
without being hindered by the wheels and the foot-plate can get
close to a work bench or the like. Since the wheels are directed
in parallel with the work bench, the occupant will be able to move
along the bench in the chair and with the seat in its outwards turned
position.
As illustrated in FIGS. 1 to 3, the main wheels are driven by electric
motors 20 through conventional chain transmissions 21. The main
wheels can be individually braked by means of the steering lever
6, which besides the swingable movement in a plane substantially
transverse to the longitudinal direction of the chair is movable
back and forth in the longitudinal direction. This latter movement
is transferred through a link-rod 22 to a lever arrangement 23,
which on one hand converts the movement to a rotary motion of a
transverse link-rod 24 and, on the other hand, transmits the movement
to a further link-rod 25 actuating a lever in operative connection
with the brakeshoes of the right main wheel. The transverse link-rod
is journalled in the chassis and transmits the rotational motion
to a corresponding linkage for the left main wheel, the brake-shoes
of which are actuated in a similar way. When the steering lever
is pulled backwards the brakes of both main wheels will be actuated
simultaneously, and the chair will be braked by a substantially
uniform braking action on the main wheels.
The arrangement of driving the main wheels with individual electric
motors provides a wheel-chair which has extremely good driving characteristics
even on sloping ground. Since the steering wheel tends to loose
its ground contact when driving up-hill, the steering gear has been
provided with micro-switches, which at certain lateral movements
of the steering lever partly disconnects one traction motor so that
the other contributes to turn the chair in the desired direction
to a degree corresponding to the lateral movement of the lever.
Further, the back and forth movements of the steering lever will
also affect a speed potentiometer in which the operating range is
positioned immediately in front of the range within which the braking
operation will occur. Thus, in the embodiment disclosed a forward
position of the steering lever means that the speed potentiometer
is entirely disconnected, i.e., the chair is driven at maximum speed.
When the steering lever is then pulled backwards, the speed potentiometer
will be progressively engaged, and when the speed potentiometer
is completely switched-in the braking operation will be initiated
which means that the main wheels are completely disconnected from
their traction motors. The braking progress from full speed ahead
to stand-still will thus proceed smoothly and without any danger
of throwing the occupant off the chair.
The structural design here described can, of course, be utilized
for single-motor operation, but this would reduce the outdoor use
of the chair. In other embodiments of the chair according to the
invention, the steering operation can, of course, be effected by
servo-technical means. |