Note: Descriptions are shown in the official language in which they were submitted.
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MANUALLY DRIVEN BATHTUB LIFT
The present invention relates to a mechanical bathtub lift seat
apparatus for assisting persons of limited mobility, such as the elderly or
disabled,
transfer into or out of a typical bathtub.
BACKGROUND
Persons having permanently limited mobility or strength to due to age
or disability may have difficulty performing certain typical daily tasks.
Entry to or exit
from a bathtub is an example of such a task, as it requires transition between
a
standing position outside the tub and a seated position upon a very low
surface
within the tub, including climbing over the side wall.
As a result, there are a number of existing products aimed at assisting
a user enter and exit the tub by easing the aforementioned transition. These
products include inflatable chairs positioned within a bathtub for lowering
and raising
the user to and from the bottom of the tub in a constantly seated position.
Other
seat assemblies can be positioned within a tub for the same purpose, but are
driven
by water actuated cylinders or electric motors. Some of these assemblies
feature
rotating seats so that the user can initially sit with his/her legs outside
the tub and
then rotate their legs over the tub wall before being lowered, eliminating the
step of
unassisted entry to the tub altogether. Other devices, typically driven by
electric
motors, are capable of actually transferring the user from a seated position
entirely
outside the walls of the tub to a seated position within. One lowering system
involves a band spanning from a wall-mounted dispenser on one side of a tub to
the
wall of the tub opposite the dispenser. An electric motor within the dispenser
slowly
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dispenses more length of the band in order to lower a user seated on the band
into
the tub. Once bathing is completed, the motor is run in an opposite direction
to
retract the band into the dispenser, thereby lifting the user back up to the
top of the
tub.
The primary problem associated with the existing bathtub lift devices is
the high cost involved. The need for components such as air compressors, seals
and adaptors for water driven devices, electric motors and control systems,
coupled
with possible installation costs, keeps many of these products financially out
of reach
for many of those in need of the assistance that would be provided. Many
elderly or
disabled persons live on limited income and cannot justify the high cost of
the
existing bathtub lift systems despite the comfort and safety levels they
offer. As a
result, there is a need for a bathtub lift apparatus that can be produced and
sold at a
reasonable cost.
SUMMARY
According to one aspect of the present invention there is provided a
bathtub lift apparatus for assisting a person into and out of a bathtub
comprising:
a base frame for being received in the tub, the base frame including a
track supported on the frame having a lower end and an upper end;
a trolley supported for movement along the track;
a seat for supporting the person thereon, the seat being supported on
the trolley device for movement with the trolley between a lower position at
the lower
end of the track and an upper position at the upper end of the track;
a rotatable drive member supported for rotation on the frame;
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an elongate driven member engaged about the drive member and
connected to the trolley for displacement of said trolley as the drive member
is
rotated; and
a driver device for rotating the drive member.
Preferably the base frame comprises two laterally spaced parallel
walls, wherein the drive member and elongate driven member are located between
said walls.
Preferably the track comprises two laterally spaced track members,
each having an upper and lower surface defining an elongate channel
therebetween
for receiving the trolley.
Each of the upper and lower surfaces of the track members may
comprise a rail.
Alternatively, the upper surface of each track member may comprise a
rail while the lower surface of each track member comprises the base frame.
Preferably there is provided roller members supported on each side of
the trolley supported for movement along the track.
Preferably the roller members are supported in pairs on axles mounted
to the trolley.
Preferably the track is non-linear between the upper and lower ends
thereof.
The seat may be pivotally supported on the trolley for pivotal motion
relative thereto.
In this arrangement, preferably there is provided:
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a pivotal mounting mechanism for pivotally supporting the seat on the
trolley for pivotal motion between the lower position where the seat is
generally
horizontal and the trolley is inclined along the track and a lifting position
where the
seat and trolley are both inclined along the track and generally parallel to
each other;
and
an abutment member mounted on the seat that abuts with the trolley to
prevent the seat from pivoting passed the lifting position where the seat and
trolley
are generally parallel.
Preferably the elongate driven member is flexible.
The elongate driven member may be endless.
Preferably the elongate driven member is guided by idler members
supported on the base frame.
Preferably one of the idler members is floatingly supported on the base
frame and biased in order to maintain tension in the elongate driven member.
Preferably the idler members comprise pulleys.
Preferably the elongate driven member comprises a chain and the
driver member comprises a sprocket for engaging the chain.
Preferably the driver device comprises a rotational member having a
series of handles circumferentially spaced therearound.
In this arrangement, preferably the handles comprise openings in the
rotational member.
Alternatively, the driver device may comprise a hand crank mechanism
for rotating the drive member.
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Preferably the driver device is accessible by the person supported in
the seat.
Preferably there is provided a locking mechanism for selectively
preventing motion of the seat relative to the base frame.
Preferably the locking mechanism is coupled between the driver device
and the base frame.
Preferably the locking mechanism comprises:
an opening in the driver device;
a corresponding opening in the base frame;
a pin for passing through the opening in the driver device into the
opening in the frame, thereby blocking motion of said driver device, and hence
the
driver member, elongate driven member, trolley and seat, relative to said
frame.
Preferably the base frame and the driver device comprise aluminum.
The present invention can be made and sold at substantially lower
costs than existing bathtub lifts as a result of its simple mechanical
structure.
Assembly is simple and affordable, as the drive system not require any
complex,
costly or custom components and the base frame is easy to fabricate. The
apparatus is hand driven and therefore does not require the use of an external
power source, such as an electric motor or air compressor and corresponding
control mechanism. Furthermore, the simplicity of the apparatus ensures that
any
maintenance will be minimal and affordable.
The driver device is reachable from the seat of the lift and therefore
may be used by a bather without outside assistance. The driver device is of
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substantial size such that the amount of torque needed to lift the bather
supported
on the seat can be achieved with relatively little force. As a result, the
bather does
not require a lot of strength to use the apparatus and is therefore less
likely to
require assistance. Using a material of relatively high strength to weight
ratio such
as aluminum to construct the frame and driver device, the weight of the
apparatus is
kept to a minimum so that the lift can be easily lowered into and lifted out
of a typical
bathtub. This is ideal for the cases where more than one person uses the tub
on a
regular basis and the lift is not always needed. There is no need for
professional
installation, which helps keep down the overall cost of the lift apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
Figure 1 is a side elevational view of the bathtub lift with the seat in the
lowered position.
Figure 2 is a side elevational view of the bathtub lift with the seat in the
raised position.
Figure 3 is a rear elevational view of the bathtub lift with the seat in the
lowered position.
Figure 4 is a rear elevational view of the bathtub lift with the seat in the
raised position.
Figure 5 is a top plan view of the bathtub lift with the seat in the
lowered position.
Figure 6 is a top plan view of the bathtub lift with the seat in the raised
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position.
Figure 7 is a cross sectional view of the bathtub lift with the seat in the
raised position as taken across line VII-VII of Figure 6.
DETAILED DESCRIPTION
The following description outlines the details of a bathtub lift for
assisting persons of limited mobility, such as the elderly or disabled,
transfer into or
out of a typical bathtub. One embodiment of the present invention is shown
from the
side in Figures 1 and 2. The bathtub lift apparatus 1 features a base frame 10
for
supporting the apparatus within the bathtub (not shown), a seat 20 for
supporting the
bather and a driver device 40 for controlling motion of the seat 20. The lift
functions
in such a manner as to move the seat 20 between a lower position as seen in
Figure
1 and a raised or upper position as seen in Figure 2. The seat 20 has a
backrest
portion 21 and a bottom portion 22 connected by an angled portion 23. The user
can sit upon the bottom portion 22 in the raised position from outside the
tub, rotate
his or her body in order to dispose each leg on an opposite side of the
apparatus
and then descend gradually to the lowered position within the tub. Once
finished
bathing, the user can then use the control device 40 to ascend back to the
raised
position and then rotate his or her legs over the tub wall in order to exit
the bathtub.
The movement of the seat is achieved through rolling motion of a
trolley 30 attached to the seat 20. The base frame 10 includes a pair of
spaced
apart parallel vertical walls 11 each having an upper edge 12 defining
generally
horizontal lower 17 and upper 18 portions and an inclined portion 16. The
walls 11
are connected and spaced apart at the end of the upper portion 16 by a
horizontal
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base member 13 at the bottom of the frame 10 and vertical end wall 15 disposed
above the base member as shown in Figures 3 and 4. A track assembly 50 is
supported on each wall 11. The track includes a rail 51 which is held above
the
base frame 10 by rail supports 52 that extend generally perpendicular to the
upper
edge 12 of the walls 11. The rail 51 and supports 52 are connected by bolts 53
in
order to form a channel 54 defined by a space between the rail 51 and the
upper
edge 12 of the wall 11. This channel 54 defines the path along which the
trolley 30
can move. The trolley includes wheels 32 disposed on each side of the trolley
body
31 for rolling motion within the channel 54. The track extends along the
inclined 16
and upper 18 portions of the upper edge 12 so that the seat 12 attached to the
rear
end of the trolley 30 can move between the lower position above lower portion
17 to
the raised position above the inclined portion 16. The inclined portion 16 is
curved in
order to provide a smooth transition of the trolley 30 to and from the upper
18 and
lower 17 portions.
Components of the drive system for the trolley are disposed between
the walls 11 of the base frame 10 and are illustrated in Figure 7. A chain 82
is
positioned around a drive sprocket 45 and guide pulleys 91, 94 and 96 and
attached
to the trolley 30 at opposite ends. A first end of the chain 82 is attaches to
the trolley
31 by means of attachment member 34 bolted to the chain 82 and the trolley
body
30 at an end opposite the seat 20. From this first end, the chain extends
around the
sprocket 45 down to a floating idler pulley 91 which is mounted on a lever 92
for
pivotal movement about an axis defined by a shaft 93 supported at each end by
a
wall 11 of the base frame 10. This arrangement allows movement of the idler
pulley
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91 in order to retain tension in the chain 82 as the trolley 30 moves along
the track
50. The chain extends from the idler 91 over a guide pulley 94 supported
between
the walls 11 by a shaft 95. The chain further extends from the guide pulley 94
around a third pulley 96 supported on a shaft 97 near the end of the lower
portion 17
opposite the inclined portion 16. This pulley 96 reverses the chain direction
back
toward the drive sprocket 45 for connection to a second trolley attachment
member
33 at an end of the trolley 30 nearest the seat 20. Similar to the first
attachment
member, the second attachment member 33 is bolted to the chain 82 and the
trolley
body 31. With the seat 20 in the lowered position as shown in Figure 1,
rotation of
the sprocket 45 in a clockwise direction drives the chain 82 in a manner that
pulls
the trolley 30 along the track 50 up the inclined portion 16 to the upper
portion 18,
moving the seat 20 toward the upper position shown in Figure 2. The shafts 95
and
97 that support the pulleys 94 and 96 at the lower portion 17 further are
connected
to a wall 11 of the base frame 10 at either so that they not only support the
pulleys,
but also keep the walls spaced apart at that end of the apparatus.
The rotation of the drive sprocket 45 is achieved by means of the
control device 40. The control device 40 includes a drive wheel 49 having a
series
of handles 41 formed by holes circumferentially spaced around the wheel. As
seen
in Figures 3 and 4, the drive wheel is attached to a rotatable member 46 by
means
of bolts 43. The rotatable member is fixed on the same shaft 45 as the drive
sprocket 81. The shaft 45 extends transversely through aligned holes in the
vertical
walls 11 of the base frame 10 near their upper edges 12 at the upper portion
18.
The shaft is free to rotate with respect to the frame 10, but lateral movement
along
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its axis is prevented by the combination of a pin 48 and blocking plate 47 as
shown
in Figures 3-6. The blocking plates 47 are supported on the shaft 45 just
outside
each vertical wall 11 and the pins 48 pass through openings in the shaft just
outside
the plates. Lateral movement of the shaft 45 with respect to the frame 10 is
prevented by the abutment of either pin 48 with the respective blocking plate
47.
Rotation of the drive wheel 40 and attached rotatable member 46 causes the
sprocket 81 to turn and drive the chain 82, resulting in motion of the trolley
30 and
attached seat 20. The wheel 40 is of sufficient size that the handles 41 are
within
reaching distance of the user when supported on the seat 20 regardless of the
position of the trolley 30 along the track 50. The amount force needed to pull
the
seated user up the inclined portion 16 is kept reasonably small as the
relatively large
radius of the driver wheel 49 ensures a proportionally large resultant torque
about
the axis of the shaft 45.
The force of gravity on the user when seated in the raised position
tends to cause the trolley 30 and attached seat 20 to descend down the
inclined
portion 16 to the lowered position. As a result, a locking mechanism is
provided for
selectively securing the trolley 30 in the track 50 at the upper portion 18 of
the walls
11 of the base frame 10, thus locking the seat 20 in the raised position above
the
inclined portion 16. A hole 42 in the driver wheel 49 is positioned in order
to align
with a corresponding hole 14 in the wall 11 of the base frame 10 on the same
side of
the lift apparatus 1 as the wheel 49 when the seat 20 is in the raised
position. A pin
70 is passed through the aligned holes 42 and 14 in order to prevent motion of
the
wheel 49 with respect to the base frame 10. Since the wheel 49 is attached to
the
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rotatable member 46 which is mounted on the same shaft 45 as the drive
sprocket,
rotation of any of these components is prevented by the pin 70. The trolley 30
and
seat 20 cannot move with the pin 70 in place as the cogs of the stationary
sprocket
81 prevent motion of the chain 82.
A pivoting mechanism 60 is provided between the trolley 30 and the
seat 20 to allow pivotal motion of the seat with respect to the trolley as
they move
along the track 50. A pair of hinges 63 provides the pivoting action between
the seat
20 and trolley 30. Each hinge has flaps 61 and 62 attached to the trolley body
31
and the seat 20 respectively. As shown in Figure 1, the hinge 63 allows the
bottom
portion 22 of the seat 20 to take on a nearly horizontal orientation in the
lowered
position at the lower portion 17 of the wall 11 even though the trolley 30 is
at an
angled orientation along the inclined portion 16. As the trolley 30 is pulled
upward
along the inclined portion 16 by the chain 82 the hinge will open further such
that the
bottom portion 22 of the seat 20 will take on an the same orientation as the
trolley
30, in other words parallel to the inclined portion 16. An abutment member 64
is
attached to the underside of the bottom portion 22 of the seat 20 in order to
prevent
the hinge 63 from opening more than 180 degrees. In the raised position shown
in
Figures 2 and 7, the hinge 63 opens under the weight of the seat 20 (and user,
if
seated thereupon) and moves the abutment member 64 into contact with the
trolley
body 31. This keeps the bottom portion 22 of the seat in a generally
horizontal
orientation in which the user can easily get on or off the seat 20 for
entering or
exiting the tub respectively.
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Due to the handles 41 circumferentially disposed about the drive wheel
49 the lift is operable by either the bather or an assistant. The bather is
lowered into
the tub from the raised position shown in Figure 2 by removing the locking pin
70
from the aligned holes 42 and 14 in the drive wheel 49 and wall 11
respectively. The
weight of the bather on the seat will tend to move the seat 20 and attached
trolley 30
down the inclined portion 16, pulling on the chain 82 and causing counter
clockwise
rotation of the sprocket 81 and the attached shaft 45. Since the driver wheel
49 is
mounted on the same shaft 45 by means of the rotational member 46, the counter
clockwise rotation can be resisted by means of the handles 41, thereby
controlling
the speed of descent of the bather towards the lowered position shown in
Figure 1.
In order to exit the tub, the seat 20 is moved upward along the inclined
portion 16
from the lowered position by rotating the driver wheel 49 clockwise by means
of the
handles 41. Once the seat 20 has reached the raised position, the holes 41 and
14
of the locking mechanism will be realigned so that the locking pin 70 can be
inserted
to lock the seat in the raised position while the bather dismounts the lift
apparatus.
The above description outlines a single embodiment of the present
invention from which a number of alternate embodiments can be derived by those
who are skilled in the art. Alternate styles of frames, seats, trolleys,
tracks, drive
members, driven members and guide members can be assembled to achieve similar
results. One alternate embodiment may employ a rope and winch for lifting and
lowering the seat, in which case the rope would only have to extend between
the
winch and the end of the trolley nearest the upper portion eliminating the
need for
the guide and tension pulleys. Another alternate embodiment could use a
notched
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belt and pulley combination instead of the chain and sprocket. Other
embodiments
could feature a trolley arranged to move along a single track member or
elongate
handles extending outward from the drive wheel transverse to the apparatus.
The
trolley and seat could also be combined into a single rigid component,
eliminating
the need for the pivoting mechanism. In this arrangement, the track would not
extend to a horizontal upper portion of the frame. The trolley would only move
along
an inclined section of track and therefore would always be oriented at the
same
angle with respect to the frame. Without the pivot mechanism, the seat would
not
move relative to the trolley but would remain fixed at an orientation similar
to that of
the lowered position of the seat in the preferred embodiment, as shown in
Figure 1.
As a result, the bottom portion of the seat would remain in a generally
horizontal
orientation when moving between the lowered and raised positions.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments of same made
within the spirit and scope of the claims without department 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..
