Wheel chair abstract
An electrically driven wheel chair for disabled persons wherein
a seat support resting on a rigid wheel frame (8) is vertically
adjustable by the aid of an electrically driven force transmitting
member (12). The seat support comprises an upper frame portion (1)
attached to rigid wheel frame (8) via two pairs of scissors-type
bars (4,5), each end of the pairs of scissors-type bars being alternately
pivotally or pivotally and slidably connected with upper seat support
frame (1), and lower rigid wheel frame (8), respectively. Front
end (18) of the upper seat support frame (1) is via supporting bars
(14,16) and linkage elements connected with wheel frame (8) and
simultaneously with pair (5) of scissors-type bars, which is actuated
by piston rod (12) to change the height of the seat support. The
vertically adjustable support permits an arrangement of footrest
and calf support providing continuous change of their position so
that the users's legs will have an anatomically correct posture
all the time. An additional pair of wheels (19) may be provided
on the front portion of the support to take over the contact with
the ground from the ordinary pair of front wheels (20) when the
seat support is lowered.
Wheel chair claims
I claim:
1. An electrically driven wheel chair comprising:
a lower frame;
a front pair of wheels and a rear pair of wheels rotatably mounted
on front and rear wheel shafts on said lower frame;
a pair of laterally spaced lower slide members mounted on said
lower frame;
an upper frame;
a pair of laterally spaced upper slide members mounted on said
upper frame;
two pairs of laterally spaced scissors-type bars, each pair of
said bars comprising a first bar and a second bar pivotally connected
at central portions thereof by a common shaft, said first and second
bars each having upper and lower ends;
said lower ends of said first bars being pivotally connected to
said rear wheel shaft and said respective upper ends of said first
bars being pivotally and slidably connected to respective ones of
said upper slide members for sliding and pivotal movement relative
to said upper frame;
said upper ends of said second bars being pivotally connected to
said upper frame and said respective lower ends of said second bars
being pivotally and slidably connected to said lower sliding member
for sliding and pivotal movement relative to said lower frame;
an extension on said lower end of each said second bar extending
upwardly at right angles to the portion of said second bar between
said common shaft and said lower end;
an upper end on each said extension;
a transverse bar connecting said upper end of each said extension;
drive means pivotally connected to said transverse bar for moving
said transverse bar reciprocally relative to said lower frame;
a first pair of laterally spaced supporting bars pivotally connected
to said lower ends of said second bars adjacent said lower slide
members and extending to front ends thereof in front of said front
wheels;
linkage means on said front ends of said first supporting bars;
a pair of second supporting bars each having one end connected
to respective linkage means and the other end pivotally connected
to a front portion of said upper frame;
calf supports and a footrest attached to said second supporting
bars; and
operating means on said upper frame for operating said drive means
for raising and lowering said upper frame relative to said lower
frame via said scissors-type bars.
2. Wheel chair as claimed in claim 1 wherein:
said drive means comprises an electrically powered piston rod means.
3. Wheel chair as claimed in claim 1 and further comprising:
a supporting arm attached to said pair of front wheels and pivotally
connected to said lower frame for lateral movement relative thereto.
4. Wheel chair as claimed in claim 2 and further comprising:
a supporting arm attached to said pair of front wheels and pivotally
connected to said lower frame for lateral movement relative thereto.
5. Wheel chair as claimed in claim 1 and further comprising:
an additional pair of wheels rotatably mounted on said second supporting
bars and having a wheel radius smaller than the wheel radius of
said front wheels, so that when said upper frame is in the lowered
position said additional wheels contact the surface on which the
wheel chair is operating and said front wheels are raised off of
said surface, and when said upper frame is in the raised position
said additional wheels contact said supporting arm for preventing
lateral movement thereof.
6. Wheel chair as claimed in claim 2 and further comprising:
an additional pair of wheels rotatably mounted on said second supporting
bars and having a wheel radius smaller than the wheel radius of
said front wheels, so that when said upper frame is in the lowered
position said additional wheels contact the surface on which the
wheel chair is operating and said front wheels are raised off of
said surface, and when said upper frame is in the raised position
said additional wheels contact said supporting arm for preventing
lateral movement thereof.
7. Wheel chair as claimed in claim 3 and further comprising:
an additional pair of wheels rotatably mounted on said second supporting
bars and having a wheel radius smaller than the wheel radius of
said front wheels, so that when said upper frame is in the lowered
position said additional wheels contact the surface on which the
wheel chair is operating and said front wheels are raised off of
said surface, and when said upper frame is in the raised position
said additional wheels contact said supporting arm for preventing
lateral movement thereof.
8. Wheel chair as claimed in claim 4 and further comprising:
an additional pair of wheels rotatably mounted on said second supporting
bars and having a wheel radius smaller than the wheel radius of
said front wheels, so that when said upper frame is in the lowered
position said additional wheels contact the surface on which the
wheel chair is operating and said front wheels are raised off of
said surface, and when said upper frame is in the raised position
said additional wheels contact said supporting arm for preventing
lateral movement thereof.
Wheel chair description
BACKGROUND OF THE INVENTION
The present invention relates to an electrically driven wheel chair
comprising a vertically adjustable seat support and calf supports
with a footrest member, and an extra pair of wheels, said members
being connected with said vertically adjustable seat support so
as to be actuated and adjusted to a desired position when the seat
support is vertically adjusted.
Commonly used wheel chairs, whether electrically driven or not,
are not provided with a vertically adjustable seat. But many of
them are collapsible, and in this connection reference is made,
inter alia, to British Patent Application No. 2,090,564 which relates
to a wheel chair the seat frame of which is of a scissors linkage
type having two possible positions, i.e. a completely folded, and
a completely extended position. Wheel chairs of said kind create
a number of problems to the user of the wheel chair. The seat portion
of the wheel chair has a vertical position which may possibly be
said to form a compromise of various considerations, but which will
very often prove to be either too low or too high.
A wheel chair user's activities, e.g. at home, are thus at present
limited by the vertical position of the wheel chair. The disabled
user will commonly not be able to reach down or close enough to
the floor to pick up, e.g. objects which the disabled person has
dropped. On the other hand, the wheel chair user will not be at
a proper level to carry out tasks, e.g. on a kitchen cabinet, or
to reach far enough up into a kitchen wall cupboard. In the bathroom
the disabled person in a wheel chair will either sit too low or
too high, dependent on the tasks to be carried out. It is often
a problem to lie down on a bed because of the difference in level
between the wheel chair seat and the bed. For wheel chair users
to function in the best possible manner at home, so that they may
also be self-reliant to a greater extent, quite extensive changes
of various installations in the home are often required. This is
especially the case with existing houses or appartments.
For a disabled person's wheelchair, especially an electrically
driven wheel chair, to be used for a driver's seat in a larger vehicle,
like a delivery van, etc., the vertical position of the wheel chair
seat portion at present requires the vehicle floor to be converted,
so that the user will be at a correct level relative to various
control means of the vehicle. It is desirable to lower the front
portion of the vehicle floor to a suitable level, but this is only
possible with one or two car makes. Commonly, the supporting structures
of a vehicle will prevent conversion which involves lowering of
the floor. If it is possible to convert the car in this manner,
this will, however, be very expensive, as mentioned above.
In most car makes where it is impossible to lower the total floor
area of the front portion of the vehicle, a limited portion of the
floor must be lowered, resulting in a well-like cavity in the existing
floor. With all the car makes of interest, however, a problem resides
in the fact that the chassis of the vehicle with supporting structures
does not permit said cavity to be placed at the required short distance
to permit the wheel chair user to reach various operating means,
like steering wheel, etc. Reconstruction of various operating means
will be required to place them closer to the driver. Obviously,
the mentioned changes which have to be made on conventional vehicles
are very expensive.
Furthermore, from German Patent DE-OS No. 25 17 418 a wheel chair
is known the seat portion of which is vertically adjustable at the
same time as the angle of inclination of the seat level proper is
adjustable. Said adjustment is carried out by the aid of two vertical
piston rods which are provided at a mutual distance, and which are
at their lower ends mounted on the chair support and at their opposite
ends are in contact with the seat portion proper. The wheel chair
according to the last mentioned patent publication, obviously, represents
a considerable improvement relative to wheel chairs which are not
vertically adjustable, and to some extent it partly eliminates some
of the disadvantages of wheel chairs that are not vertically adjustable.
A considerable disadvantage of the wheel chair according to said
patent publication, however, is that the maximum lowering capacity
of the seat portion will be limited by the length of the piston
rod, which in turn also will determine the distance between the
lowermost and the highest position of the seat portion. The greatest
disadvantage, however, is the fact that the piston rod prevents
extensive lowering of the seat portion. Another considerable disadvantage
of the disclosed wheel chair is that two piston rods are required
to provide reasonably acceptable stability of the seat portion.
This is both bulky and expensive.
Another common aspect of existing wheel chairs is that the user
will often find himself in a much lower position than, e.g. a person
standing up, in a conversation. This is very unfortunate and may
have a restraining effect on communication with other people.
Other disadvantages which may not be directly connected with the
vertical position of the wheel chair user in case of conventional,
and preferably electrically operated wheel chairs is that they tend
to instability when driven on rough ground. Special problems also
arise in connection with high kerbstones which the user of a wheel
chair meet when driving onto a pavement.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide, especially
an electrically driven wheel chair where the above disadvantages
are eliminated to a maximum degree. One aspect of the invention
is to eliminate part of the disadvantages connected with the vertical
level of a wheel chair seat. The applicant, thus, sought to provide
a wheel chair with a seat which is continuously adjustable in the
vertical direction from an extremely low position to a very high
position, and where, simultaneously with height adjustment of the
seat an adjustment of calf supports with a footrest is achieved,
said latter means, thus, being automatically adjusted with the level
of the seat. This object is achieved by the aid of a seat support
in the shape of two pairs of scissors-type bars, the central portions
of which are rotatably interconnected in pairs by the aid of a common
shaft, and the arms of which are rotatably and/or slidably attached
to a lower frame at their lower ends, and to an upper frame portion
at their upper ends, said frame portion forming a support for a
seat with accessory means, like operating means, etc., and which
in the direction of the front ends of the wheel chair are connected
to, inter alia, calf supports with a footrest. The chair is characterized
in that the upper frame portion of the seat support is at both sides
and preferably at its front half, provided with slide means in which
a first set of scissors-type bars is rotatably running, which at
the opposite end is rotatably mounted on the wheel shafts of the
rear wheels or the lower frame, that upper frame portion also at
both sides in its rear portion is rotatably connected with the second
set of scissors-type bars, which extend downwards to slidable and
rotatable connections with the lower frame proper, and from which
said scissors-type bars extend as two orthogonal arms which are
finished by a connecting transverse bar which is linked to drive
means for movement of said bar, and that the scissors-type bars
close to the slides are hinged to a first set of holding bars extending
forwards some distance ahead of the front wheels, where they are
provided with members, from which a second set of holding bars extends
to a hinged connection with the front portion of upper frame portion,
and that calf supports with a footrest are attached to said second
set.
In a preferred embodiment of the invention the drive means comprises
an electrically driven piston rod.
Another aspect of the invention is to provide a wheel chair which
can be driven in a relatively stable manner on rough ground. According
to the invention this object is achieved by the fact that the supporting
arm to which the front wheels are attached is hinged to the wheel
chair frame, so that said supporting arm is movable laterally.
Another aspect of the invention is to provide conditions to facilitate
driving up onto a pavement or crossing a higher threshold or the
like with a wheel chair.
According to the invention this object is achieved by the fact
that a pair of wheels having a relatively small radius is provided
in such a manner on the front end of the vertically adjustable seat
support that said pair of wheels, when the seat support is lowered
will take over ground contact from the ordinary pair of front wheels
which are, thus lifted slightly from the ground. In order to stabilize
the wheel chair when the seat support is at maximum height, which
may occur at standstill, said additional wheel pairs are, furthermore,
provided in such a manner on the seat support that they are in this
position in contact with the upper edge of said supporting arm which
is then no longer movable laterally.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention is disclosed in more detail
below, with reference to the accompanying drawing, wherein:
FIG. 1 is a top plan view of the frame with wheels, a vertically
adjustable seat support with mounted additional wheel pairs, but
not with mounted calf supports and footrest and also shows an electric
drive means for vertical adjustment of the seat support, the seat
support being shown in a lowered position;
FIG. 2 is a sectional view taken along line A--A' in FIG. 1 with
the seat support shown at maximum height; and
FIG. 3 is a view similar to FIG. 2 with the seat support in the
same lowered position as in FIG. 1.
DETAILED DESCRIPTION
It will be most practical to start by discussing FIG. 2. The front
portion of upper side beams 1 of the seat support is provided with
guide rails 2. By the aid of rollers a first set of scissors-type
bars 4 runs in said guide rails 2 and is rotatably mounted on the
shaft of rear wheels 10. Upper side beams 1 of the support are at
their rear ends rotatably connected with a second set of scissors-type
bars 5, which, via a common shaft 6 is rotatably connected with,
approximately the middle of first mentioned scissors-type bars 4.
From shaft 6 the second set of scissors-type bars 5 extends down
to the wheel frame proper 8 which is provided with guide rails 9.
By the aid of rollers 11 scissors-type bars 5 are slidably connected
with guide rails 9. At the location of said slidable connection
the scissors-type bars change into sides of an angle 5' extending
obliquely upwards and having their end portions connected by a transversal
bar 7 which is hinged to a piston rod 12 which is driven by an electromotor
13. Adjacent to slide connections/rollers 11 angle arms 5 are pivoted
to a first set of supporting bars 14 which extend slightly ahead
of front wheels 20, where said first supporting rods 14, via members
15, change over into a second set of supporting bars 16 which are
hinged to upper transverse bar 18 of the seat support. From the
second set of supporting bars additional wheel pair 19 is suspended
by the aid of angle bars 17. The pair of front wheels 20 is attached
to supporting arm 21 which is hinged to transverse beam 22 of wheel
frame 8, so that supporting arm 21 is movable laterally. In the
drawing calf supports 24 and foot-rest 26 are shown secured to the
second set of supporting bars 16.
FIG. 1 is provided with numeral references as far as possible,
and these numeral references representing the same means as those
of FIG. 2, it is considered unnecessary to discuss them in detail.
As regards FIG. 3, numeral references are also the same as in FIG.
2. The Figure shows the seat support in a lowered position and clearly
illustrates how all members are folded together inside each other
to form a very compact unit.
Adjustment of the height of the seat support, like any other operation
of the wheel chair is made by the aid of actuating means which are
readily accessible to the user sitting in the wheel chair. For raising
the seat support motor 13 is activated, and piston rod 12 exerts
a pulling force on bar 7. Pair 5 of scissors-type bars which is
slidably connected with frame 8 in slide 9 is then pulled rearwards
on the frame. At the same time pair 4 of scissors-type bars which
is slidably connected with the upper side beam in its slide 2, is
pulled rearwards on said side beam 1. In this manner the support
is continuously raised into a desired position. The movement of
upper part 1 of the support, i.e. the location where the seat is
mounted, occurs in the vertical plane and essentially without any
movement in the horizontal plane. The seat is, thus, raised straight
upwards. Calf supports 24 and footrest 26 are mounted on the upper
portion of each supporting bar 16 and, thus, follow the movement
of said supporting bars in case of vertical adjustment, which will
ensure an anatomically correct posture of the user' s legs. In case
of maximum height of the support FIG. 2 shows how the additional
pair of wheels 19 is in contact with the laterally movable supporting
arm 21 of the pair of front wheels 20, which arm is thus locked
and can no longer move laterally. This results in increased stability
of the wheel chair in this position.
For lowering the seat support, piston rod 12 will push bar 7 and,
thus, pairs 4 and 5 of scissors-type bars in their slidable connections
in upper beam 1, and frame 8, respectively in a forward direction.
Supporting bars 14 and 16 are then slightly "folded" due
to hinged connection 15. In a folded position wheel pair 19 contacts
with the ground. |