U.S. patent number RE30,954 [Application Number 06/072,641] was granted by the patent office on 1982-06-01 for wheelchairs.
Invention is credited to Edward H. D. Carson, Royal Smith.
United States Patent |
RE30,954 |
Smith , et al. |
June 1, 1982 |
Wheelchairs
Abstract
A wheelchair is disclosed which is convertible into a wheeled
stretcher, wherein the chair seat will assume a comfortable angle
with respect to the horizontal when the chair is in the seating
position and will assume a horizontal position coplanar with the
back of the chair when the chair is in the stretcher position. The
chair seat and back may be locked into any relative position
between a fully erect seated position and a fully reclined
stretcher position. Leg support members which are connected to the
chair may assume any angular position with respect to the
horizontal without regard for the relative positions of the seat
and back of the chair. The leg support members may have their
lengths independently adjusted.
Inventors: |
Smith; Royal (St. Petersburg,
FL), Carson; Edward H. D. (Largo, FL) |
Family
ID: |
22108899 |
Appl.
No.: |
06/072,641 |
Filed: |
September 5, 1979 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
707203 |
Jul 21, 1976 |
04046418 |
Sep 6, 1977 |
|
|
Current U.S.
Class: |
297/118; 297/81;
297/DIG.4 |
Current CPC
Class: |
A61G
5/006 (20130101) |
Current International
Class: |
A47C
1/031 (20060101); A47C 1/032 (20060101); A61G
5/00 (20060101); A47C 013/00 (); A47C
001/035 () |
Field of
Search: |
;297/90,DIG.4,322,323,80,81,83,119,118 ;5/67 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Zugel; Francis K.
Attorney, Agent or Firm: Brady, O'Boyle & Gates
Claims
We claim:
1. A wheelchair convertible into a wheeled stretcher,
comprising:
a pair of wheeled support frame members horizontally spaced from
one another, each having a corresponding rearwardly positioned
first pivot and a forwardly positioned second pivot at
substantially the same elevation;
a pair of first levers, each having a first length and pivotally
mounted on a respective one of said first pivots;
a chair back support having two lateral sides each proximate to a
respective one of said support frame members, each rigidly mounted
to the free end of a corresponding one of said first levers;
a pair of second levers, each having substantially said first
length and pivotally mounted on a respective one of said second
pivots;
a pair of front arms, each rigidly mounted at an intermediate point
to the free end of a respective one of said second levers;
a pair of linkages, each having a first end pivotally connected to
a respective one of said front arms at a point a second length
above said intermediate point and a second end pivotally connected
to a corresponding one of said lateral sides of said back support
at substantially said second length above said mounting point for
the corresponding one of said first levers;
a pair of extendable chair seat supports, each proximate to a
respective one of said support frame members, each comprising a
first and second portions which slideably engage one another with
the free end of said first portion pivotally connected to a
corresponding one of said lateral sides of said back support at a
third length below said mounting point for the corresponding one of
said first levers and with the free end of said second portion
pivotally connected to a corresponding one of said front arms at a
fourth length below said intermediate point, said third length
being greater than said fourth length;
whereby a chair seat supported by said pair of extendable seat
supports, will assume a comfortable angle with respect to the
horizontal when the chair is in a seating position, and will assume
a horizontal position coplanar with the back of the chair when the
chair is in a stretcher position.
2. The apparatus of claim 1, which further comprises:
a first tube pivotally mounted to said pair of support frame
members;
a second tube mounted in sliding engagement with said first tube,
with its free end pivotally connected to said second portions of
said pair of extendable seat supports;
locking means mounted on said first tube and in selective
frictional engagement with said second tube;
whereby said chair seat and back may be locked in any relative
position between a fully erect seated position and a fully reclined
stretcher position.
3. The apparatus of claim 1, which further comprises:
a leg support member pivotally mounted on said second portions of
said pair of extendable seat supports;
a first tube pivotally mounted on said second portion of one of
said pair of extendable seat supports, rearwardly of the mounting
point for said leg support member;
a second tube mounted in sliding engagement with said first tube,
with its free end pivotally connected to said leg support
member;
locking means mounted on said first tube and in selective
frictional engagement with said second tube;
whereby said leg support member can assume any angular position
with respect to the horizontal without regard for the relative
positions of said seat and back of the chair.
4. The apparatus of claim 3, wherein said leg support member
further comprises:
a first and second outer tubes, each pivotally mounted on said
second portions of said pair of extendable seat supports;
a first and second inner tubes, each mounted in sliding engagement
with a respective one of said outer tubes;
a foot rest means mounted on the free ends of said inner tubes;
a locking means mounted on one of said outer tubes and in selective
frictional engagement with the corresponding one of said inner
tubes;
whereby said leg support member may have its length adjusted.
5. The apparatus of claim 4, which further comprises two of said
leg support members being so mounted on the chair, capable of
independent adjustment of their relative positions. .Iadd. 6. A
wheelchair convertible into a wheeled stretcher, comprising:
a pair of wheeled support frame members, horizontally spaced from
one another, each having a corresponding rearwardly positioned
first pivot, and a forwardly positioned second pivot at
substantially the same elevation;
a pair of first lever means, each having a first length and
pivotally mounted on a respective one of said first pivots;
a chair back support having two lateral sides, each proximate to a
respective one of said support frame members and each rigidly
mounted to the free end of a corresponding one of said first lever
means;
a pair of second lever means, each having substantially said first
length and pivotally mounted on a respective one of said second
pivots;
a pair of front arm members, each rigidly mounted at an
intermediate point to the free end of a respective one of said
second lever means;
a pair of linkages, each having a first end pivotally connected to
one of said front arm members at a point a second length above said
intermediate point and a second end pivotally connected to a
corresponding one of said lateral sides of said back support at
substantially said second length above said mounting point for the
corresponding one of said first lever means;
a pair of seat support members, pivot means connecting one end of
said pair of seat support members to said chair back support at a
third length below said mounting point for the corresponding one of
said first lever means, the opposite end of said pair of seat
support members being supported by the lower portion of said front
arm members at a fourth length below said intermediate point, said
third length being greater than said fourth length to thereby
position said seat support at an angle .theta. to the horizontal;
and lost motion means operatively connected between said opposite
end of said seat support members and the lower portion of said
front arm members; the chair back support, the front arm members,
the linkages and associated pivot points to said front arm members
and said back support, the seat support members and associated
pivot means on said chair back and lost motion means on said front
arm members, all being substantially horizontally coplanar when the
chair is folded to a stretcher position,
whereby a chair seat supported by said pair of seat support members
will assume a comfortable angle with respect to the horizontal when
the chair is in a seating position, and will assume a horizontal
position coplanar with the back of the chair when the chair is in a
stretcher position. .Iaddend. .Iadd. 7. The apparatus of claim 6
which further comprises a pair of leg support members operatively
supported by said chair and being capable of independent adjustment
of their relative positions. .Iaddend..Iadd. 8. The apparatus of
claim 6 which further comprises:
a first tube pivotally mounted to said pair of support frame
members;
a second tube mounted in sliding engagement with said first tube,
with its free end pivotally connected to said pair of seat support
members;
locking means mounted on said first tube and in selective
frictional engagement with said second tube;
whereby said chair seat back may be locked in any relative position
between a fully erect seated position and a fully reclined
stretcher position. .Iaddend. .Iadd. 9. The apparatus of claim 6
which further comprises:
leg support means pivotally mounted on said pair of seat
supports;
a first tube pivotally mounted on said pair of seat supports
rearwardly of the mounting point for said leg support means;
a second tube mounted in sliding engagement with said first tube,
with its free end pivotally connected to said leg support means;
and
locking means mounted on said first tube and in selective
frictional engagement with said second tube; whereby said leg
support means can assume any angular position with respect to the
horizontal without regard for the relative positions of said seat
and back of the chair. .Iaddend..Iadd. 10. The apparatus of claim 9
wherein said leg support means further comprises:
first and second outer tubes each pivotally mounted on said pair of
seat supports;
first and second inner tubes, each mounted in sliding engagement
with a respective one of said outer tubes;
foot rest means mounted on the free ends of said inner tubes;
and
locking means mounted on one of said outer tubes and in selective
fricitional engagement with the corresponding one of said inner
tubes;
whereby said leg support means may have its length adjusted.
.Iaddend.
Description
FIELD OF THE INVENTION
The invention disclosed relates to wheelchairs and more
particularly relates to wheelchairs which are convertible into
wheeled stretchers.
BACKGROUND OF THE INVENTION
Hospital equipment and invalid home care equipment has become quite
expensive, so that it becomes economic to combine the functions of
several pieces of hospital apparatus to enable a single, combined
function apparatus to have a higher frequency of utilization and
therefore a greater return on investment. Following this philosphy,
wheelchairs have been made, in the prior art, which are convertible
into wheeled stretchers, thereby combining the function of a
conventional wheelchair for transporting a patient in a seated
position, with the function of a wheeled stretcher for transporting
a patient in a lying position. Prior art convertible wheelchairs
however, have suffered from several deficiencies. One deficiency is
that in order that the seat of the prior art convertible wheelchair
can assume a coplanar position with respect to the back of the
chair when it is in the stretcher position, the seat must remain
horizontal when the chair is in the erect seated position. A
horizontal seat for a chair is uncomfortable for the patient who
must remain seated thereon for long periods of time. Designers of
conventional chairs have recognized that a seat which assumes a
slight angle with respect to the horizontal, toward the back of the
chair, is much more comfortable to sit in for long periods of time.
However, prior art convertible wheelchairs have suffered from this
source of discomfort to the patient. A second deficiency of prior
art wheelchairs is that the leg support member which supports the
patient's leg is not angularly adjustable with respect to the
horizontal in a manner independent of the relative positions of the
seat and the back of the chair. Thus the flexibility of the chair
to accommodating various patient ailments requiring the special
positioning of the patient's limbs, has not been available in prior
art convertible wheelchairs. Still a third deficiency of prior art
convertible wheelchairs is that the length of the leg support
members for the chair have been fixed, causing the chair to be
incapable of accommodating a variety of leg lengths.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide a convertible
wheelchair having a seat which will assume a comfortable angle with
respect to the horizontal when the chair is in a seating position
and will assume a horizontal position coplanar with the back of the
chair when the chair is in a stretcher position.
It is still another object of the invention to provide a
convertible wheelchair wherein the chair seat and back may be
locked in any relative position between a fully erect seated
position and a fully reclined stretcher position.
It is still a further object of the invention to provide a
convertible wheelchair having leg support members which can assume
any angular position with respect to the horizontal with no regard
for the relative position of the seat and back of the chair.
It is still a further object of the invention to provide a
convertible wheelchair having leg support members whose lengths may
be independently adjusted.
SUMMARY OF THE INVENTION
These and other objects, features and advantages of the invention
are accomplished by the convertible wheelchair invention disclosed
herein. The convertible wheelchair has a seat supported by a pair
of extendable seat supports, which assume a comfortable angle with
respect to the horizontal when the chair is in a seating position
and will assume a horizontal position coplanar with the back of the
chair when the chair is in a stretcher position. A pair of wheeled
support frame members are horizontally spaced from one another and
have a corresponding rearwardly positioned first pivot and a
forwardly positioned second pivot at substantially the same
elevation. A pair of first levers, each having a first length, are
pivotally mounted on respective ones of the first pivots. A chair
back support having two lateral sides, each proximate to a
respective one of the support frame members, is rigidly mounted to
the free end of the corresponding one of the first levers. A pair
of second levers, each having substantially the first length, are
pivotally mounted on respective ones of the second pivots. A pair
of front arms are each rigidly mounted at an intermediate point to
the free end of a respective one of the second levers. A pair of
linkages connect the upper end of each respective arm to the
corresponding lateral side of the chair back support. The pair of
extendable chair seat supports each comprise a first and second
portions which slidably engage one another with the free end of the
first portion pivotally connected to the corresponding one of the
lateral sides of the back support at a given length below the
mounting point for the corresponding one of the first levers, and
the free end of the second portion is pivotally connected to the
corresponding one of the front arms at a shorter length below the
intermediate point on the arm. With this mechanism, the chair seat
which is supported by the pair of extendable seat supports, will
assume a comfortable angle with respect to the horizontal when the
chair is in a seating position and will assume a horizontal
position coplanar with the back of the chair in the stretcher
position.
DESCRIPTION OF THE FIGURES
These and other objects, features and advantages of the invention
will be more particularly appreciated with reference to the
accompanying figures.
FIG. 1 is a three dimensional overall view of the convertible
wheelchair invention.
FIG. 2 is a more detailed breakaway view of the chair seat
mechanism.
FIG. 3a illustrates the relative position of the elements for the
chair seat mechanism when the chair is in a fully erect seating
position.
FIG. 3b illustrates the chair of FIG. 3a, at a position
intermediate between the fully erect seated position and a fully
reclining stretcher position.
FIG. 3c illustrates the chair of FIG. 3a, in the fully reclining
stretcher position.
FIG. 4 further illustrates the leg support mechanism of the
chair.
FIG. 5 is a detailed illustration of the locking mechanism for the
seat of the chair.
DISCUSSION OF THE PREFERRED EMBODIMENT
The convertible wheelchair invention is shown in an overall three
dimensional view in FIG. 1. There is seen that a pair of wheeled
support frame members 2, each have larger rear wheels 8 and smaller
forward wheels 10 attached thereto. The wheeled support frame
members 2 are horizontally spaced from one another by means of the
struts 4 and 6 and the forward portion of each support frame member
is connected to the rearward portion by an additional strut 7. Each
wheeled support frame member 2 has a corresponding rearwardly
positioned first pivot 12 and a forwardly positioned second pivot
14 at substantially the same elevation above the ground.
As shown in FIG. 2 and 3a, a pair of first levers 16 each have a
first length x and are pivotally mounted on a respective one of the
first pivots 12. The chair back 18 is supported by the back support
20 which has lateral sides 22 and 22', each proximate to a
respective one of the support frame members 2. Each of the lateral
sides 22 and 22' is rigidly mounted at 15 to the free end of a
corresponding one of the first levers 16.
A pair of second levers 24 each have substantially the first length
x and are pivotally mounted on a respective one of the second
pivots 14. A pair of front arms 26 are each rigidly mounted at an
intermediate point 28 to the free end of the respective one of the
second levers 24.
A pair of linkages 30 each have a first end pivotally connected at
31 to a respective one of the front arms 26 at a point a second
length w above the intermediate point 28. The linkages 30 have a
second end pivotally connected at 33 to a corresponding one of the
lateral sides 22 of the back support 20 at substantially the second
length w above the mounting point 15 for the corresponding one of
the first levers 16. The linkages 30 can serve as arm rests for the
chair.
The chair seat 32 is supported by a pair of extendable chair seat
supports 34. Each chair seat support 34 is proximate to a
respective one of the support frame members 2. Each extendable
chair seat support 34 comprises a first portion 36 and the second
portion 38 which slidably engage one another. The free end of the
first portion 36 is pivotally connected at 40 by means of the cross
member 42 to a corresponding one of the lateral sides 22 of the
back support 20 at a third length Y below the mounting point 15 for
the corresponding one of the first levers 16. The free end of the
second portion 38 is pivotally connected at 44 by means of the
cross member 46 to a corresponding one of the front arms 26 at a
fourth length y below the intermediate point 28. The third length Y
is greater than the fourth length y so that the extendable seat
support 34 will assume a comfortable angle .theta. with respect to
the horizontal when the chair is in a seating position as is shown
to better advantage in FIG. 3a and will assume a horizontal
position coplanar with the back 18 of the chair when the chair is
in the stretcher position, shown to better advantage in FIG.
3c.
The chair seat 32 and back 18 may be locked in any relative
position between a fully erect seated position as is shown in FIG.
3a and a fully reclined stretcher position as is shown in FIG. 3c
by means of the seat locking means such as the set screw 51 shown
in FIGS. 3a-3c or the locking shoe 82 shown in FIG. 5. A cross
member 49 is rigidly connected to the struts 7 on both of the
wheeled support frame members 2. A first tube 74 is pivotally
mounted by means of the pivot mount 73 to the cross member 49. A
second tube 50 is mounted in sliding engagement with the first tube
74, with its free end pivotally connected to the cross member 46
which, in turn, is connected to the pair of extendable seat
supports 34. A locking means mounted to the first tube 74 comprises
the extensions 76 having a first end rigidly mounted to the tube 74
and a second end which forms a pivot point 78 for the arms 80.
Pivotally attached to the arms 80 is a locking shoe 82 which can
selectively frictionally engage the second tube 50. Locking arms 80
are loaded by the tension spring 84 so as to normally cause the
engagement of the locking shoe with the tube 50. Control cable 86
connected to the arms 80, permits the selective engagement of the
locking shoe with respect to the tube 50, by actuating knob 88.
FIG. 4 illustrates the leg support member 52 which can assume any
angular position with respect to the horizontal without regard for
the relative position of the seat 32 and back 18 of the chair. The
leg support member 52 is pivotally mounted on the cross member 46.
The cross member 46 connects to the second portions 38 of each of
the pair of extendable seat supports 34. A first tube 62 is
pivotally mounted by means of the pivot 54 on the second portion 38
of one of the pair of extendable seat supports 34 in a position
rearward of the mounting point at the cross member 46 for the leg
support member 52. A second tube 60 is mounted in sliding
engagement with the first tube 62, with its free end pivotally
connected at pivot 56 to the leg support member 52. A locking means
64 which may be a set screw for example, is mounted on the first
tube 62 and may be placed in selective frictional engagement with
the second tube 60. In this manner, the leg support member 52 can
assume any angular position with respect to the horizontal without
regard for the relative position of the seat 32 and back 18 of the
chair. There are two leg support members 52 and 52' and each has
the corresponding elements described above and are capable of
independent adjustment of their relative position.
Each leg support member 52 and 52' may have its length adjusted to
accommodate varying leg sizes. The leg support member comprises a
first and second outer tubes 66, each pivotally mounted on the
cross member 46. The cross member 46 is, in turn, mounted to the
second portion 38 of each of the pair of extendable seat supports
34. A first and second inner tubes 68 are each mounted in sliding
engagement with a respective one of the outer tubes 66. A foot rest
means 72 which may be, for example, a folding foot rest of
conventional design, is mounted on the free ends of the inner tubes
68. A locking means 70 which may be for example, a set screw, is
mounted on one of the outer tubes 66 and may be placed in selective
frictional engagement with the corresponding one of the inner tubes
68. In this manner, each leg support member 52 and 52' may have its
length independently adjusted.
Although the invention has been described with some specificity, it
is understood that the present disclosure is made only by way of
example and that many changes in the details of construction and
the combination and the arrangement of the elements may be made
without departing from the spirit and the scope of the
invention.
* * * * *