[0001] This invention relates to bathing apparatus, in particular, to apparatus for bathing
for use by the elderly, infirm or other users with mobility problems.
[0002] It is known that one method available to humans for washing their body is to use
a bath, sometimes known as a bathtub. A standard bath is essentially a container suitable
for containing water which is of sufficient size to allow a human to at least partially
immerse themselves in any water held within the bath. The bath generally comprises
a base and one or more side walls extending from the base in a generally upward direction
(when the bath is orientated for use), the number of side walls being dependent on
the shape of the base. The upper edges of the side walls (when the bath is orientated
for use) collectively define an open mouth. Access to the water is generally gained
by a user climbing through the mouth and into any water held within the bath. All
further description of the structure of baths generally and / or baths of the present
invention and / or apparatus according to the present invention for use in association
with baths will be made on the basis that the bath is orientated for use. That is
the base of the bath is the vertically lowermost of the bath base and the side wall
or walls.
[0003] For some users of baths, such as the elderly, infirm and or those with mobility problems,
a standard bath as just described is difficult and / or unsafe and / or impossible
to use because to use the bath the user must be able to climb into the bath and lower
themselves into the water. They must then, subsequently be able to raise themselves
out of the water and climb out of the bath. For the elderly, infirm and or those with
mobility problems, such acts can be difficult, if possible at all.
[0004] It is known to provide baths which have a door in the or one of the side walls, that
door being sealable so that when it is in a closed position the bath is capable of
retaining water. When the bath is empty, the door can be moved to an open position
and a user can walk through the aperture created in the side wall. This overcomes
the need for a user to lower themselves through the mouth of the bath, and can be
much easier for a user who is elderly, infirm and or with mobility problems to use.
[0005] It is also known to provide a seat lift. A seat lift is generally comprised of a
seat and, optionally, a seat back together with a mechanism that can move the seat,
and seat back if present, vertically between an upper position in which it is relatively
easy for a user to sit on the seat, and a lower position in which the seat, and seat
back if present, are wholly or substantially within the volume defined by the bath
base and side wall or walls and may be at least partially submerged in any water retained
within the bath.
[0006] The mechanism of a known seat lift is generally an X frame leading to a substantially
vertical movement of the seat between the upper and lower positions.
[0007] The control and or powering of the movement of the seat upwards or downwards between
the upper and lower positions is by a suitable control and / or power means. Such
a seat lift can be of considerable assistance to a user who has difficulty in lowering
themselves into a bath or rising from a bath.
[0008] According to a first aspect of the present invention there is provided a seat lift
for use in association with a bath comprising a bath base and at least one side wall,
the seat lift comprising a seat, a seat back hingedly connected to the seat, a torsion
spring, and a guide means adapted to guide the seat in reversible movement between
a lower position in which the seat is close to the bath base and an upper position
in which the seat is remote from the bath base characterised in that
the guide means is configured so that movement of the seat between the lower and upper
positions comprises both vertical and lateral movement of the seat relative to the
base of the bath;
the seat back may move between a first seat back position in which the seat back is
substantially upright and a second seat back position in which the seat back is orientated
relative to the seat so that a user sitting on the seat and with their back on the
seat back is leaning backwards;
the torsion spring biases the seat back to rotate around the hinge connecting the
seat back to the seat toward the first seat back position;
the torque exerted by the torsion spring is smaller when the seat is in the lower
position than when the seat is in the upper position.
[0009] The advantage of seat lifts comprising both a seat and a seat back is that the user
may lean against the back and gain considerable stability thereby.
[0010] The use of a torsion spring to bias the seat back into the first seat back position
is that the seat back can assist a user sit substantially upright if they need such
assistance. Further, the biasing has the effect that the seat back is not unyielding
when a user sits in it. This means that when a user sits on the seat and leans on
the seat back the seat back may, dependent on the force exerted by the user on the
seat back, rotate a little about the hinge that connects it to the seat absorbing
the force of the user on the seat back. The torque exerted by the torsion spring may,
when the force of the user leaning on the seat back is dissipated, bias the seat back
towards the first seat back position helping the user sit substantially upright.
[0011] When the seat and seat back are in the lower position the user of the seat lift may
want to lie back into water that is in the bath. The lower torque exerted by the torsion
spring relative to the torque at the upper position may allow the user to lie back
with relative ease and without the need for significant strength.
[0012] In some embodiments of the present invention the torque exerted by the torsion spring
when the seat and seat back are in the lower position may be set to a predetermined
value.
[0013] In some embodiments of the present invention means may be provided to allow the torque
exerted by the torsion spring when the seat and seat back are in the lower position
to be altered by a user or other person. The value to which the torque is adjusted
may, at least in part, be determined by one or more physical characteristics of the
user. Such characteristics may include but not be limited to the weight, strength,
and or height of the user. This has the effect that the amount of force a user needs
to exert to push the seat back into the second seat back position may be configured
to suit the user of the seat lift.
[0014] It is preferred that if the bath base has a longitudinal extent the lateral movement
of the seat is substantially in the direction of that longitudinal extent. It is known
for baths to have a bath base that is approximately rectangular or stadium shaped.
In such instances, it is preferred that the lateral movement of the seat is substantially
parallel to the longitudinal axis of the bath base.
[0015] In some embodiments of the invention when the seat back is in the first seat back
position the angle between the seat and the seat back is between around 90° and around
115°, between around 90° and around 110°, between around 95° and around 110°, or between
around 100° and around 110°.
[0016] In some embodiments of the present invention when the seat back is in the second
seat back position the angle between the seat and the seat back is between around
115° and around 180°, between around 110° and around 180°, between around 110° and
around 160°, or between around 110° and around 140°.
[0017] In some embodiments of the present invention, the seat lift is so configured that
the movement of the seat and seat back from the upper position to the lower position
causes the torque exerted by the torsion spring to be reduced and movement of the
seat and seat back from the lower position to the upper position causes the torque
exerted by the torsion spring to increase.
[0018] In some embodiments of the present invention, the seat lift is so configured that
the torsion spring interacts with the bath base when the seat is less than a predetermined
distance from the bath base. Such interaction may be the result of a direct contact
between the bath base and the torsion spring. Alternatively, the interaction may be
indirect, that is via one or more mechanical elements such as, but not exclusively,
arms, levers or pivots. In some embodiments, the torsion spring may be adjusted by
appropriate means dependent upon the proximity of the seat to the bath base.
[0019] In some embodiments of the present invention, there is a linear relationship between
the position of the seat and seat back between the lower and upper positions and the
position of the seat back between the second and first seat back positions. For example,
when the seat and seat back are in the lower position the seat back is in the second
seat back position, when the seat and seat back are a proportion of the distance between
the lower and upper positions the seat back is the same proportion of the angular
distance between the second and first seat back positions, and when the seat and seat
back are in the upper position the seat back is in the first seat back position.
[0020] In other embodiments, the relationship between the position of the seat and seat
back between the lower and upper positions and the position of the seat back between
the second and first seat back positions is non-linear, albeit that when the seat
and seat back are in the lower position the seat back is in the second seat back position,
and when the seat and seat back are in the upper position the seat back is in the
first seat back position.
[0021] In other embodiments, commencement of movement of the seat back between the second
and first seat back positions is allowed or caused when the seat and seat back reaches
or passes through a predetermined position between the lower and upper positions.
The predetermined position may be different depending on whether the seat and seat
back is moving from the lower position to the upper position or from the upper position
to the lower position. In some such embodiments, until the seat and seat back reaches
or passes through the predetermined position the seat back is held or locked in the
seat back position it occupied before the seat and seat back started to move toward
the predetermined position.
[0022] In some embodiments, when the seat and seat back moves from the upper position to
the lower position the predetermined position between the upper and lower positions
at which movement of the seat back from the first seat back position to the second
seat back position is allowed or caused is less than 10cm, less than 8cm, less than
6cm, less than 4cm or less than 2cm from the lower position. In some such embodiments,
until the seat and seat back reaches or passes through the predetermined position
the seat back is held or locked in the first seat back position.
[0023] In some embodiments, when the seat and seat back moves from the lower position to
the upper position the predetermined position between the lower and upper positions
at which movement of the seat back from the second seat back position to the first
seat back position is allowed or caused is less than 10cm, less than 8cm, less than
6cm, less than 4cm or less than 2cm from the lower position. In some such embodiments,
until the seat and seat back reaches or passes through the predetermined position
the seat back is held or locked in the second seat back position, and once the seat
and seat back has passed through the predetermined position or shortly thereafter
the seat back is held or locked in the first seat back position.
[0024] In some embodiments of the present invention, there is a linear relationship between
the position of the seat and seat back between the lower and upper positions and the
amount of torque exerted by the torsion spring with the maximum amount of torque being
exerted when the seat and seat back are in the upper position and the minimum amount
of torque being exerted when the seat and seat back are in the lower position.
[0025] In other embodiments, the relationship between the position of the seat and seat
back between the lower and upper positions and the amount of torque being exerted
by the torsion spring is non-linear, albeit that the maximum amount of torque is exerted
by the torsion spring when the seat and seat back are in the upper position and the
minimum amount of torque being exerted by the torsion spring when the seat and seat
back are in the lower position.
[0026] In some embodiments, a change in the amount of torque that is exerted by the torsion
spring occurs when the seat and seat back reaches or passes through a predetermined
position between the lower and upper positions. The predetermined position may be
different depending on whether the seat and seat back is moving from the lower position
to the upper position or from the upper position to the lower position.
[0027] In some embodiments, when the seat and seat back moves from the upper position to
the lower position the predetermined position between the upper and lower positions
at which a change in the amount of torque that is exerted by the torsion spring is
commenced is less than 10cm, less than 8cm, less than 6cm, less than 4cm or less than
2cm from the lower position.
[0028] In some embodiments, when the seat and seat back moves from the lower position to
the upper position the predetermined position between the lower and upper positions
at which a change in the amount of torque that is exerted by the torsion spring is
commenced is less than 10cm, less than 8cm, less than 6cm, less than 4cm or less than
2cm from the lower position.
[0029] The position of the seat and seat back between the lower position and upper position
may be determined by sensors or by physical interference or interaction between the
seat and / or seat back and the guide means, or interference or contact between the
seat and / or seat back and / or a mechanism mounted directly or indirectly on the
seat or seat back and the bath in which the seat lift of the present invention is
used.
[0030] In some embodiments of the present invention seat back is biased toward the first
seat back position and when the seat and seat back are in the lower position the bias
toward the first seat back position is relatively light allowing the seat back to
move into the second seat back position. In such an embodiment, the bias toward the
first seat back position may increase when the seat and seat back starts to move away
from the lower position toward the upper position.
[0031] In some embodiments of the invention the torsion spring is a dual torsion spring.
The torsion spring is preferably of a material that will not be damaged by regular
immersion in water.
[0032] In some embodiments of a seat lift according to the present invention the seat lift
further comprises a tilting lever, in which the tilting lever is fixed to the seat
back and a contact portion of the tilting lever extends below the seat. The tilting
lever is preferably so configured that the contact portion of the tilting lever is
spaced from the seat when the seat back is in the first seat back position and movement
of the contact portion of the tilting lever to move toward the seat causes movement
of the seat back from the first seat back position toward the second seat back position.
[0033] The hinge between the seat back and the seat and / or the tilting lever may be so
configured to allow hinging of the seat back relative to the seat only between the
first and second seat back positions.
[0034] The hinged connection between the seat back / tilting lever assembly and the seat
may comprise a biasing means biasing the seat back towards the first seat back position.
The biasing means may be a torsion spring or a mechanical equivalent thereof.
[0035] The contact portion of the tilting lever may comprise one or more contact means adapted
to contact the base of the bath without causing damage to the surface of the bath
base. It is preferred that the contact means are adapted to move across the surface
of the bath base without causing damage to the bath base. In some preferred embodiments
of the present invention, the contact means may comprise one or more rollers or pads
of material softer than the surface of the bath base.
[0036] The seat of the seat lift of the present invention may be a rigid seat or a non-rigid
seat. It is preferred but not essential that a non-rigid seat is associated with a
rigid seat frame. It is preferred that the seat of the seat lift of the present invention
is of a material that is not damaged by repeated immersion in water.
[0037] A seat lift of the present invention may further comprise at least one arm rest.
In some preferred embodiments of the present invention the bath seat comprises two
arm rests arranged so that a user sitting on the seat is between the arm rests.
[0038] In some embodiments of the present invention at least one arm rest is fixed in position
relative to the seat and or the seat back. In other embodiments of the present invention
at least one arm rest is pivotably attached to the seat or the seat back. In other
embodiments of the present invention at least one arm rest is in sliding engagement
with the seat or the seat back.
[0039] In some embodiments of the present invention at least one arm rest is or may be so
positioned that when the seat and seat back is in the lower position the or each arm
rest is wholly or substantially adjacent to a side wall of a bath with which the bath
seat is being used. In such embodiments, it is preferred that when the seat and seat
back moves from the lower position to the upper position the or each arm rest moves
so that the user has lateral support from the or each arm rest, even when the or each
arm rest is above the upper edge of the side wall or walls of the bath.
[0040] According to a second aspect of the present invention there is provided a seat lift
according to the first aspect of the present invention which is integral with a bath
comprised of a bath base and at least one side wall.
[0041] In some embodiments of the second aspect of the present invention the guide means
of the seat lift are attached to, integral with, and / or defined by one or two side
walls of the bath. In some such embodiments, the guide means may be comprised of at
least one channel each of which is defined by or attached to a bath wall and within
which one or more guide rails or guide tracks are provided, and the seat and or seat
back are provided with means for directly or indirectly interacting with the walls
of the channel and or each guide rail or track.
[0042] The interaction means may be caused to move along the channel or guide rail or track
by suitable means. Such suitable means may comprise, without limitation, one or more
of a drive belt, helical screw, chain, and or other equivalent mechanical power or
movement transmission means.
[0043] In other embodiments, the guide means may comprise one or more actuators, rams or
their mechanical equivalent and one or more stabilising rods in which the or each
stabilising rod is associated with a bush or bearing fixed to a side wall of a bath
or onto a rigid frame onto which the side walls of the bath are also fixed. The actuators,
rams or their mechanical equivalent are preferably linear and are adapted to move
the seat between the lower and upper positions.
[0044] In some embodiments of the second aspect of the present invention bath further comprises
a door through a side wall of the bath. The door is preferably of dimensions suitable
to allow a user to walk into the bath. It is preferred in such embodiments that the
seat lift is so located relative to the bath and the door that when the seat and seat
back are in the upper position the user can sit on the seat once the user has walked
into the bath through the door with no or minimal travel of the user across the surface
of the bath base. Such an arrangement is particularly beneficial because it avoids
the user having to move around within the bath more than is necessary thus minimising
the risk of slipping within the bath.
[0045] In such arrangements it is preferred that the guide means are so configured and orientated
that when the seat and seat back move toward the lower position the seat and seat
back / user is moved away from the door. This allows the door to be located toward
a corner of the bath if the bath has a bath base of approximately rectangular or stadium
shaped base. This position is a strong position to site a door in a bath wall.
[0046] The present invention will be further described and explained by way of example and
with reference to the accompanying drawings in which
Figure 1 shows an embodiment of a bath incorporating an embodiment of a seat lift
according to the present invention;
Figure 2 shows a side view of a bath and seat lift as shown in Figure 1 when the seat
and seat back are in the upper position;
Figure 2A shows a detail of Figure 2;
Figure 3 shows a side view of bath and seat lift as shown in Figure 1 when the seat
and seat back are in the lower position;
Figure 3A shows a detail of Figure 3; and
Figure 4 shows a schematic detail for the guide means of the bath and seat lift as
shown in Figure 1.
[0047] With reference to Figure 1, there is shown a bath (2) comprising a bath base (4)
and side walls (6), (8), (10) and (12). The side wall (6) includes an aperture (14)
which may be sealingly closed by a door (not shown) so that the bath (2) can retain
water introduced into it via a tap (16). The bath (2) is provided with a drain (not
shown) through which water retained in the bath (2) may be removed from the bath if
that is desired.
[0048] Integral with the bath (2) is a seat lift (20) comprising a seat (22), a seat back
(24), and first and second armrests (26) and (28). The seat (22) and the armrests
(26) and (28) are fixed to each other via arm pillars (30) and (32).
[0049] As shown in Figure 1, the seat lift (20) is in its upper position, being a position
when the seat lift (20) is furthest from the bath base (4) and, in particular, the
seat (22) is sufficiently high above the bath base (4) that a user, including a user
who is elderly, infirm or has mobility issues, can rest their hands or forearms on
armrests (26) and (28) and sit upon the seat (22). The ability to rest their hands
or arms on the armrests (26) and (28) is of significant benefit to the user because
those armrests are sufficiently high that the user can use the armrests (26) and (28)
to maintain stability when they sit on the seat (22).
[0050] When the seat lift (20) is in the upper position as illustrated in Figure 1, the
seat back (24) is in the first seat back position, that seat back position being one
in which the angle between the seat (22) and the seat back (24) is between about 90°
and about 100° this is also illustrated in Figure 2. The seat back (24) is biased
by a torsion spring (44) into the first seat back position. The torsion spring exerts
a torque of x Nm. When the seat lift (20) is in the lower position, the torsion spring
exerts a torque of y Nm where x > y. This change of torque is caused by means not
shown. In some embodiments of the invention the torsion spring (44) interacts with
the bath base (4) to reduce the torque exerted by the tension spring (44) when the
seat (22) is within a predetermined distance of the bath base (4).
[0051] As may be seen from Figures 2 and 2A, when the seat lift (20) is between the upper
position (illustrated in Figure 1) and a lower position (illustrated in Figures 3
and 3A) the seat back (24) remains in the first seat back position. This seat back
position gives a user (not illustrated) a secure and stable seating position. The
user may, via control means (not shown), cause the seat lift (20) to travel between
the upper and lower positions.
[0052] As may be seen in Figures 2 and 2A, the seat lift (20) further includes a tilting
lever (40). The tilting lever (40) is rigidly connected with the seat back (24) (although
in alternative embodiments the seat back (24) and tilting lever (40) may be integral
with each other) and the seat back (24) is hingedly attached to the seat (22) at a
hinge (42). The hinge (42) is at least partially surrounded by a torsion spring (44)
which acts on the tilt lever (40) biasing the tilt lever (40) in a clockwise direction
as illustrated in Figures 2 and 2A. As a result, the torsion spring (44) also biases
the seat back (24) into the first seat back position.
[0053] When the seat lift (20) moves from the upper position downward and backward toward
the bath wall (12) it moves towards the position illustrated in Figures 3 and 3A.
As the seat lift (20) approaches the bath base (4) a roller (46) attached to the tilt
lever (40) makes contact with the bath base (4) and rolls a small distance along the
surface of bath base (4) as the tilt lever (40) is forced to rotate in an anticlockwise
direction against the bias of the torsion spring (44). This anticlockwise movement
of the tilt lever (40) causes the seat back (24) to move into to a second seat back
position as illustrated in Figure 3 wherein the seat back is proximal to the bath
wall (12). This allows a user sitting on the seat (22) to be able to lie back to a
certain degree and enjoy their bath.
[0054] The tilt lever (40) is provided with a stop (48) which, when the seat lift (20) reaches
the lower position, bears upon the underside of the seat (22). This has the effect
of preventing excess forces on the tilt lever (40) and renders the seat lift (20)
more stable when in the lower position than it would otherwise be without the presence
of stop (48).
[0055] When the seat lift (20) moves away from the lower position and toward the upper positon
the torsion spring (44) pushes the tilt lever (40) in a clockwise direction so moving
the seat back (24) from the second seat back position toward the first seat back position.
[0056] The motive power for moving the seat lift (20) between the upper and lower position
is provided by a pair of linear actuators (60) one of which is schematically illustrated
in Figure 4. The linear actuators (60) are electrically powered and controlled by
control means that are not shown. Typically the control means would be incorporated
in an armrest (26) or (28) or an arm pillar (30) or (32). Typically the control would
be via rocker switches or the like.
[0057] The mechanism associated with movement of the seat lift (20) illustrated in Figures
4 has an equivalent arrangement of actuator and stabilising rods associated with armrest
(28) but which is not illustrated.
[0058] The linear actuator (60) is orientated at an angle relative to vertical with the
result that when the actuator arm (62) either moves out of the actuator (60) or into
the actuator (60) the armrest (26) upon which the actuator arm (62) bears moves away
from the bath wall (12) or towards the bath wall (12) respectively. Alternatively
expressed, the seat lift (20) moves along part of the longitudinal axis of the bath
base (4) when the actuators (60) are in operation. Also provided are first and second
stabiliser rods (64) and (66) which are attached to the armrest (26). A first end
of stabiliser rods (64) and (66) pass through bushes (68) and (70) respectively. The
bushes (68) and (70) are of a sufficient dimension in the direction of the longitudinal
axis of the respective stabilising rods (64) and (66) that the bushes (68) and (70)
have the effect of preventing lateral movement of the stabilising rods (64) and (66).
This has the result that the armrest (26) is stable both whilst it is in movement
as a result of operation of the actuator (60) and when the actuator (60) is not causing
movement.
[0059] The actuator (60) and bushes (68) and (70) are fixed relative to the bath wall (6)
by virtue of their attachment to a rigid bath frame (not shown) onto which the bath
walls are also attached. This has the result that the armrests (26) and (28) are in
a fixed stable position relative to the bath (2). For aesthetic reasons the bath walls
(6) and (8) can be double skinned walls and the bath frame (not shown), actuators
(60) and bushes (68) and (70) may be located between the skins. Also located between
the skins may be appropriate power supply means and other electronics associated with
the control of the movement of the seat lift (20).
1. A seat lift for use in association with a bath comprising a bath base and at least
one side wall, the seat lift comprising a seat, a seat back hingedly connected to
the seat, a torsion spring, and a guide means adapted to guide the seat in reversible
movement between a lower position in which the seat is close to the bath base and
an upper position in which the seat is remote from the bath base characterised in that
the guide means is configured so that movement of the seat between the lower and upper
positions comprises both vertical and lateral movement of the seat relative to the
base of the bath;
the seat back may move between a first seat back position in which the seat back is
substantially upright and a second seat back position in which the seat back is orientated
relative to the seat so that a user sitting on the seat and with their back on the
seat back is leaning backwards;
the torsion spring biases the seat back to rotate around the hinge connecting the
seat back to the seat toward the first seat back position;
the torque exerted by the torsion spring is smaller when the seat is in the lower
position than when the seat is in the upper position.
2. A seat lift according to claim 1 in which the bath base has a longitudinal extent
and the lateral movement of the seat is substantially in the direction of that longitudinal
extent.
3. A seat lift according to claim 1 or 2 in which in which the first seat back position
is such that the angle between the seat and the seat back is between around 90° and
around 115°, between around 90° and around 110°, between around 95° and around 110°,
or between around 100° and around 110°.
4. A seat lift according to any of claims 1 to 3 in which the second seat back position
is such that the angle between the seat and the seat back is between around 115° and
around 180°, between around 110° and around 180°, between around 110° and around 160°,
or between around 110° and around 140°.
5. A seat lift according to any of claims 1 to 4 in which movement of the seat and seat
back from the upper position to the lower position causes the torque exerted by the
torsion spring to be reduced and movement of the seat and seat back from the lower
position to the upper position causes the torque exerted by the torsion spring to
increase.
6. A seat lift according to claim 5 in which the torsion spring interacts with the bath
base when the seat is less than a predetermined distance from the bath base.
7. A seat lift according to any of claims 1 to 6 in which the torsion spring is a duel
torsion spring
8. A seat lift according to any of claims 1 to 7 in which the seat lift further comprises
a tilting lever, in which the tilting lever is fixed to the seat back and a contact
portion of the tilting lever extends below the seat.
9. A seat lift according to claim 8 in which the contact portion of the tilting lever
is spaced from the seat when the seat back is in the first seat back position and
movement of the contact portion of the tilting lever to move toward the seat causes
movement of the seat back from the first seat back position toward the second seat
back position.
10. A seat lift according to claims 8 or 9 in which the contact portion of the tilting
lever may comprise one or more contact means adapted to contact the base of the bath
without causing damage to the surface of the bath base.
11. A seat lift according to any of claims 1 to 10 in which the seat lift further comprises
at least one arm rest.
12. A bath comprising a bath base and at least one side wall in combination with a seat
lift according to any of claims 1 to 11.