EP0403235A1

EP0403235A1 - An improved lifting mechanism

Info

Publication number: EP0403235A1
Application number: EP19900306411
Authority: EP
Inventors: William David Steadman
Original assignee: EXTEND-A-CARE Ltd; EXTEND A CARE Ltd
Priority date: 1989-06-15
Filing date: 1990-06-12
Publication date: 1990-12-19
Also published as: CA2018995A1

Abstract

A lifting mechanism for use in lowering or raising a user, such as on entering or leaving a bath (11) or other confined space, comprising at least one support member (50) turnable about an axis, a flexible web (51) associated with the support member (50) and having a further support member (58) by which the web (51) may be suspended in an open loop spanning the bath (11) or other space, and means for extending or retracting the web (11) by the action of the said one support member (50) whereby to enlarge or reduce the loop, motor drive means (53) for actuating the said one support member (50) whereby to cause it to turn in one direction or the other about the said axis and means (56) sensitive to the tension in the web (51) and operative to disable the said motor drive means (53) when the tension in the web (51) exceeds a predetermined threshold value.

Description

The present invention relates generally to an improved lifting mechanism, and particularly to apparatus for use in lifting or lowering a user's body such as on leaving or entering a bath or other confined space.
The elderly or infirm have some difficulty in moving from an upright, standing position to a sitting or lying position due to the weakening of their limbs due to old age or infirmity. This is particularly noticeable when rising from armchairs, sofas or the like and when entering or leaving a bath.
Although liftable platforms for assistance with this operation are known these known devices are complex, expensive, unreliable and, in the case of bath lifting devices, difficult to clean and to seal in the bath.
The present invention seeks to provide simple, economical, reliable and easy to use apparatus suitable for use in assisting a user to raise or lower his or her body between standing, sitting and lying positions.
One prior art device for assisting the disabled and infirm to enter and leave a bath is described in Australian Patent AU-A-75236/87 which discloses a lifting device for use in lowering a person into and out of a bath, and comprising a sheet of flexible material having a length sufficient to drape into and extend across the width of the bath, means for securing one side of the sheet adjacent one side of the bath and means positionable adjacent the other side of the bath for advancing and retracting the sheet into and from the bath to increase the effective length of the sheet. The advancing means disclosed is a hand crank mechanism although an electric motor is proposed.
The present invention seeks to provide an improvement over that known lifting mechanism, in particular by providing a structure which can be secured to the wall without necessarily requiring a reinforcing structure, and which will provide adequate force for lifting a person without risk of dislodging the apparatus from the wall.
According to one aspect of the present invention, therefore, there is provided a lifting mechanism for use in lowering or raising a user, such as on entering or leaving a bath or other confined space, comprising at least one support member turnable about an axis, a flexible web associated with the support member and having a further support member by which the web may be suspended in an open loop spanning the bath or other space, and means for extending or retracting the web by the action of the said one support member whereby to enlarge or reduce the loop, characterised in that there are provided motor drive means for actuating the said one support member whereby to cause it to turn in one direction or the other about the said axis and means sensitive to the tension in the web and operative to disable the said motor drive means when the tension in the web exceeds a predetermined threshold value.
By providing tension-sensitive means it is possible to ensure that the drive motor is automatically switched off when the tension reaches a predetermined threshold, normally that which is reached when the web is stretched taut across the top of the bath, corresponding to the position of greatest lift. Any further rotation of the motor once the web has been drawn taut to this position would risk damaging the equipment, especially in view of the high gearing such a motor must have in order to be able to apply the appropriate force to raise a person from the sitting position in the bath.
In a preferred embodiment of the invention there may further be provided means for supporting a user on the loop symmetrically as the said elongate support member is turned to raise or lower the loop. Such means may comprise a linked second support such that both ends of the loop are wound or unwound together, or may be means for ensuring that a user will slide easily over the surface of the web. This may comprise a seat on rollers, or simply a sleeve surrounding the web, with a low friction material, such as PTFE, coated on the surfaces facing the web. Such a sleeve may benefit from the provision of a plurality of reinforcing rigid or substantially rigid elements extending transversely of the length of the web.
By using a web of flexible laminar material it is possible both to adapt the supporting part of the apparatus to the user's particular shape and/or infirmity, whilst at the same time providing a secure support without the requirement for a rigid platform. The use of a flexible laminar web to form a loop also acts to cradle the user securely so that a feeling of security is engendered in the most economical and reliable manner.
In a preferred embodiment of the invention the said second support is itself turnable about a longitudinal axis and there are provided rotation synchronisation means operable to synchronise the rotation of the first and second support members about their respective axes in order to achieve the above-mentioned symmetrical positioning of the loop between the supports.
In either case there may be provided a rigid platform supported on or by the web loop for a user to rest a part of his anatomy. In such an embodiment, although the cradle effect is to some extent lost, the user has a more conventional flat support surface on which to rest whilst being assisted to rise or descend.
Of course, if, as referred to above, only a single rotatable support is provided, with the opposite free edge of the loop being secured fixedly, it is necessary, in order to maintain the symmetry of support as the web loop is wound in or out from the rotatable support, to allow the rigid platform to move with respect to the loop, and for this purpose the platform may be supported on the web loop by rollers or other such rolling elements allowing relative movement between the web and the platform to take place as the web is unrolled from or rolled onto the rotatable support member.
In embodiments of the present invention which will be described in more detail below the supports are particularly adapted to be carried on or fixed in association with the sides of a bath, and in such an embodiment individual supports are provided for attachment to respective opposite sides of a bath. The apparatus of the present invention is not restricted, however, to use as a bath accessory, but may also be used, for example, to assist a user to rise or descend from or into an armchair or sofa, or even a hard chair with suitable adaptation. The apparatus of the present invention may provide the whole supporting force for the user's body, or may supplement the force which the user can exert on the ground and/or on the chair, table, bath or the like with his or her arms and/or legs.
The use of a flexible web for supporting the user in a cradle-like open loop also avoids the necessity for any support members to be placed directly on the bottom of the bath or to pass through it so that the user may be lowered right to the bottom of the bath (apart from the thickness of the web) to allow him or her to bathe conventionally whilst nevertheless being able to provide all the necessary support for secure elevation to rise from the bath when desired. Indeed, embodiments of the invention may be formed as a combined bath and lift combination, in which case the floor of the bath may be recessed to accept the web.
The rotatable support members may, in an embodiment adapted to be fitted to a bath, be so arranged as to be mountable on opposite edges of the bath and it is preferred that such elongate support members are shorter than the overall length of the bath as is the flexible web loop so that the user's feet and legs may come into direct contact with the bottom of the bath in a manner which will be described in more detail hereinbelow.
The apparatus of the invention preferably further includes a fixed handrail on a part of the support structure of the apparatus with respect to which the rotatable support members are turnable. The provision of such a handrail greatly assists the infirm or elderly in orientating their bodies in the most appropriate manner to allow for them to be positioned on the loop for raising or lowering motion.
The fixed part of the structure may comprise at least one rigid inverted U-shape member the limbs of which bear one end of each of the rotatable support members.
It is convenient for the rotatable support members to be so arranged, in relation to the web, that they both rotate in the same directional sense when taking up the slack in the loop, and also when paying out the loop for enlargement thereof. This simplifies the interconnection arrangements and/or any drive means which may be provided. It would nevertheless be possible to envisage an embodiment in which the rotatable support members are turnable in opposite directions in order to elevate or lower the loop.
The rotatable support member or members may be driven to rotate by electric, hydraulic or pneumatic drive means controlled by switches or valves in a control panel preferably accessible directly to the user. It may be preferable, for some embodiments, however, for the control panel to be accessible to an assistant but inaccessible to the user. In a presently preferred embodiment of the invention the control switch may in fact be carried on an arm projecting over the bath and accessible to the user. The arm may be the control member which actuates the switch as will be described in more detail below. Alternatively a pressure operated switch may be linked by a pneumatic line to a bath or other like such member which can be squeezed by a user to control the apparatus.
If the rotatable members are driven by hydraulic means such as an hydraulic motor, the liquid constituting the power source may be the water in the mains system delivered to the bath. Elevating or lowering movements of the flexible web loop may be achieved, therefore, by allowing water to be driven through or to escape through the hydraulic motor. Whatever the motive power it is preferred that the transmission includes a worm gear which effectively locks the loop in position except when driven. There is thus no risk that the user may be dropped suddenly into the bath in the event of a power failure or breakdown in the motor.
In embodiments of the present invention adapted for use on a domestic bath there may additionally be provided means for clamping a fixed frame part of the apparatus to the rim or to parallel rims of the bath whereby to hold the apparatus securely in position during use.
The present invention also comprehends a bath having assisted entry means as defined hereinabove.
Although it has been indicated above that a web of flexible material forming a loop less than the full length of the bath is preferred (in this case the dimension of the loop parallel to the bath is that transverse the curvature, that is parallel to a generatrix of the loop and to the axes of the rotatable members from which the loop is suspended) it would be possible to produce an embodiment in which the user is raised entirely from the bath when the loop is reduced in size, for which purpose it would preferably be provided with a full length platform having apertures or perforations to allow the passage of water therethrough upon raising or lowering. Since the platform of such an embodiment would largely obstruct the interior of the bath when the loop has been reduced in dimensions it is preferable that the fixed frame on which the rotatable support members are carried be formed as a tipping frame to allow the whole apparatus to be swung away from its use position to allow access for cleaning. Reinforcement of the web may be provided by way of stiffening battens extending parallel to the length of the roller.
The present invention also comprehends apparatus for use in raising or lowering a user's body, comprising a flexible web wound onto two rollers with an open loop of the web supported between them to form a cradle, means interconnecting the rollers for synchronised rotation thereof whereby to enlarge or reduce the size of the loop from both ends simultaneously and symmetrically before lowering or raising the body of a user supported thereby. A bath and lift combination formed as an embodiment of the invention may also be provided with an auxiliary platform alongside the bath to assist a user in getting onto and off the lifting mechanism.
Various embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a conventional bath fitted with a bath lifting device formed in accordance with the principles of the present invention;
Figure 2 is a schematic sectional view taken on the line II-II of Figure 1;
Figure 3 is a sectional view similar to that of Figure 2, illustrating a second embodiment of the invention;
Figure 4 is a perspective view of a further embodiment of the invention;
Figure 5 is a perspective view of a bath lift formed as a further embodiment of the invention; and
Figure 6 is a detail of a part of the embodiment of Figure 5.

Referring now to the drawings, the embodiment shown in Figures 1 and 2 is adapted for use on a conventional bath generally indicated 11 having two parallel upper edges 12, 13 on which the bath lifting apparatus generally indicated 14 is supported. In the example illustrated the bath 11 is shown in position against a wall 15 so that the upper bath edge 12 is not a free edge but is obstructed to one side by the wall 15, whilst the edge 13 is a free exposed edge.
The bath lift apparatus 14 comprises two parallel rollers 16, 17 journalled at opposite ends in rigid end frames 18, 19 the latter of which is formed as an inverted U-shape frame having limbs 20, 21 to avoid obstruction with the taps 22, 23 of the bath 11.
Wound on the rollers 16, 17 is a flexible laminar web 24 and, as can be seen particularly in Figure 2, the web 24 is wound clockwise onto the roller 16 and onto the roller 17 so that rotation of these rollers in the same direction causes them to wind on the web 24 and rotation in an anti-clockwise direction causes them both to unwind the web 24. The frame member 18 includes means (not shown) for interconnecting the rollers 16, 17 so that they turn together, in the same direction, in a synchronised manner. Such interconnection means may comprise a chain, belt or other flexible elongate such linkage, or alternatively may include bevel gears and a transmission shaft. The roller 17, moreover, is driven from an electric motor 25 via a drive pulley 26 over which passes a drive belt 27. The motor 25 is controlled from a switch panel 28 suspended from a link rod 29 joining the two support frames 18, 19 and extending parallel to and just below the roller 17. The support frame 18 is generally L-shape, having a downwardly extending limb 31, and a clamp member 30 secures this limb firmly against the side of the bath 11. A similar clamping arrangement may secure the limb 21 of the inverted U-shape support frame 19.
A handrail 32 extends from the junction between the limb 20 and the bight portion of the inverted U-shape frame 19 and the support frame 18 to which it is rigidly secured by a crank limb 33. This handrail is rigidly fixed although in other embodiments it may be mounted on a ratchet mechanism linked to the rollers so that back and forth motion of the handrail, operated by the user himself, may raise or lower the web. For this purpose of course, the handrail must be rockable.
Finally, the web 24 is reinforced by a rigid platform member 34 secured, in this case, to the underside of the web 24 and held in place by any suitable fixing means, such as adhesive, fastening elements or the like.
In use of the apparatus of the invention the two frames 18, 19 are fitted over a bath with the rollers 16, 17 extending parallel to the upper bath edges 12, 13, and the clamp 30 (and any other suitable clamping means not illustrated) are activated to secure the apparatus 14 in position. By acting on the switch panel 28 (assuming that the electric motor 25 is connected to a suitable isolated or transformed power supply) the motor 25 is caused to rotate to drive the roller 17 and, via the transmission mechanism (not illustrated) the roller 16 in a clockwise direction to take up the web 24 and stretch it tightly between the two rollers. In this position, as illustrated in Figure 1, the platform member 34 lies flush with the upper rim of the bath and it is a simple matter for an intending bath occupant to lower himself or herself onto the platform 34 and swing his or her legs onto the platform whilst gripping the handrail 32. Energisation of the motor 25 via the switch panel 28 will now cause rotation of the pulley 26 in an anti-clockwise direction driving the roller 17 and, correspondingly, the roller 16 in an anti-clockwise direction to allow the web 24 to be wound off the rollers 16, 17 forming a loop of web material and lowering the platform 34 into the water in the bath until it rests on the bath floor. The rigid platform 34 need be only of relatively thin stiff material and consequently when lowered onto the bath floor occupies no significant volume so that the bath occupant can utilise the bath in a conventional manner. When it is desired to leave the bath the switch panel 28 is again activated (this being safe, even with wet hands, due to the transformed, 12 Volt, electricity supply thereto) and the rotation of the motor 25 causes both the rollers 16, 17 to turn in a clockwise direction taking up the web 24 until a position close to that illustrated in Figure 2 is reached, at which point the motor 25 ceases to operate and the user can easily swing his or her legs off the edge (there being no need for them to be raised in order to pass the bath edge 13 since the platform 35 is substantially flush therewith) and utilising the handrail 32 and, if necessary, additional supporting means, the user may then leave the bath.
Emptying and cleansing of the bath can be achieved simply by releasing the clamp 30 and lifting the bath lift 14 away. In other embodiments the rigid frame supporting the rollers may be pivotally attached to the bath or a fixed support such as the wall 15, to allow the frame to be swung upwards out of the use position illustrated in Figures 1 and 2 to an out-of-use position at which it allows access to the bath interior for emptying and cleaning.
The embodiment of Figure 3 differs from that of Figures 1 and 2 in the provision of only a single roller 17′, the roller 16 being replaced by a rigid elongate attachment 16′. In this embodiment the platform 34′ is formed as a separate element resting on the web 24′ and displaceable with respect to the loop of web material formed when the roller 17′ is unwound or partly unwound by subsidiary elongate rollers 36, 37 which allows the platform 34′ to remain in a horizontal position with an occupant seated or semi-recumbant thereon as the web 24′ is unwound from or wound onto the roller 17′.
The web 24 may be made of any suitable flexible water impermeable material such as plastics, nylon or the like.
As can be seen in broken outline in Figure 3, it is also possible to provide a secondary platform or table 38 above the platform 34′, turnable about a vertical axis X-X to assist a user in turning round.
The embodiment illustrated in Figure 4 has a single roll 40 of web 41 a free end 42 of which is secured to a support frame 43. The roll 40 is connected to a motor 44 having an internal worm screw gear box to provide a geared down slow speed output, and the whole assembly is mounted on a reinforcing back plate 45 which can be secured to a wall against which the bath 11 is placed. The back plate 45 is itself reinforced by a support frame 46 which spans the bath 11 and incorporates a support frame 43 carrying the free end 42 of the web 41. This may be fitted with a releasable connection to facilitate cleaning. The support frame 46 also includes a horizontal hand grip member 47 which serves as additional assistance for steadying the user in use of the bath.
Although, in this embodiment, no provision is made directly for maintaining the loop of web 41 symmetrical, it has been found that by appropriately wetting the web 41 prior to sitting on it that the water acts as an adequate lubricant to allow the user to slide over the surface of the web 41 as the loop is enlarged on one side by turning the roller 40 in a direction such as to unwind the web 41. This may further be enhanced by providing a sleeve, shown in broken outline in Figure 5, over the web 41 and provided with a low friction material such as polytetrafluorethylene on its inner faces which contact the web 41. This then provides a fixed surface on which the user may rest, whilst nevertheless allowing free sliding motion over the web 41 as it is enlarged or reduced by turning the roller 40 in one direction or the other. The reinforcing frame 46 also helps to support the roller 40 and back plate 45 in situations where the fixing to the wall against which the bath 11 is placed may not be entirely secure, or for use in circumstances where the bath 11 is not placed against a wall at all, and the roller 40 supported on the back plate 45 is then entirely located by the frame 46.
Figure 5 illustrates a further embodiment of the invention, similar to that of Figures 4 the further embodiment comprises a roll 50 of a web 51 which can be extended in a loop across a bar generally indicated 75 and a free end 57 of which is formed into a loop about a rod 58 which can be releasably engaged in blocks 59 at the foot of the bath.
The embodiment of Figure 5 is specifically adapted to be fitted to the wall adjacent to the bath without requiring any other modifications apart from the provision of the blocks 59, and is therefore specifically adapted for situations where the bath may be used by the elderly or infirm person with the aid of the lifting mechanism and by able-bodied persons without the aid of a lifting mechanism.
The roll of 50 is mounted on a back plate 52 by means of side arms 73, 73′ and securely fixed to the wall by a plurality of screws as indicated in Figure 5. Electric motor 53 is also carried on the back plate 52 and linked by a worm gear transmission 54 and further reduction gear transmission 55 to the roll of 50 to enable slow rotation of the roll of 50 at a high force to be achieved. The motor 53 is connected by leads 63 to a switch 62 determining the direction of rotation of the motor 53, and the switch 62 is connected by leads 64 to a transformer 66 supplied from the mains circuit generally indicated 70. This ensures low voltage supply to the motor 53, which is safe for use in the moist environment of a bathroom.
The web 51 is provided with a plurality of battens 72 extending parallel to the length of the roll 50, and the path of the loop is guided by a guide bar 56 carried on the side plates 73, 73′ of the back plate 52. One end of the rod 56 is carried in a slot 56′ in the guide plate 73. the rod 56 is biased by a spring (not illustrated) to one end of the slot 56′ and engaged by a microswitch 54 which is switched if the rod 56 is displaced, against the action of the spring, along the slot 56′. the setting of the spring determines the tension in the web 51 at which the rod 56 is displaced along the slot and, for this purpose a rather strong spring is required. This may be adjustable to vary the tension in the web 51 at which the rod 56 is displaced along the slot 56′ to trigger the microswitch 74. the microswitch 74 is connected in the circuit of the motor 53 by conductors (not shown) and acts to disconnect the motor when triggered.
Finally, the side plate 73 carries a pivoted support 61 carrying a frame 60 which acts as a further steady for the user and, furthermore, incorporates an on/off switch (not shown) for energisation of the motor. The frame 60 may be fitted at either side of the back plate 50 to fit baths with tapes at one end or the other.
Finally, an auxiliary platform 71 adjacent the bath may also be provided. This may be a separate item as illustrated or may be pivotally fixed to the bath so that it can be folded away along the front edge of the bath when not in use. In use of the apparatus of the invention the user positions himself or herself onto the loop of the web 51, by first sitting on the auxiliary platform 71, swinging his legs over the bath and then shuffling sideways onto the loop 51. The direction of motion of the motor 53 selected by actuating the switch 62 and then by pressing or pushing on the frame 60 to trigger the on/off switch, the motor 53 is caused to turn to lower the loop of web 51 and allow the person to be lift formed as a further embodiment of the invention; and lowered into the bath. In an alternative embodiment the roller and motor unit may be positioned under the bath at a concealed location.

Claims

1. A lifting mechanism for use in lowering or raising a user, such as on entering or leaving a bath or other confined space, comprising at least one support member turnable about an axis, a flexible web associated with the support member and having a further support member by which the web may be suspended in an open loop spanning the bath or other space, and means for extending or retracting the web by the action of the said one support member whereby to enlarge or reduce the loop, characterised in that there are provided motor drive means for actuating the said one support member whereby to cause it to turn in one direction or the other about the said axis and means sensitive to the tension in the web and operative to disable the said motor drive means when the tension in the web exceeds a predetermined threshold value.

2. A lifting mechanism according to Claim 1, characterised in that the said further support member also includes means for retracting or extending the material of the web whereby the said open loop may be enlarged or reduced by simultaneous operation of the said one support member and the said further support member such that enlargements and reductions in the size of the loop are effected symmetrically.

3. A lifting mechanism according to Claim 2, characterised in that the said one support member and the said further support member include rotatable means acting to wind the laminar material of the web onto or unwind it from a respective said roller or like such member.

4. A lifting mechanism according to any of Claims 1 to 3, characterised in that the said one support member and the said further support member are carried by a support frame adapted to be mounted to or over a bath, and including a fixed hand rail extending along at least one side of the bath.

5. A lifting mechanism according to any preceding Claim, characterised in that it includes an arm projecting over the bath cavity or other space from which a user is to be lifted or into which the user is to be lowered, the said arm incorporating a control member by which elevation or lowering of the said open loop of the web is controllable.

6. A lifting mechanism according to Claim 5, characterised in that the said control switch means is operable by moving the said arm itself.

7. A lifting mechanism according to any preceding Claim, characterised in that the motor drive means for actuating the said one support member whereby to cause it to turn in one direction or the other about the said axis includes a transmission having a worm gear drive the pitch of the work is such that the transmission is locked against reverse motion drive of the worm gear by the worm wheel whereby to ensure that motion of the cradle constituted by the open loop of the web remains stationary unless the motor is energised to turn in one direction or the other.

8. A lifting mechanism according to any preceding Claim, characterised in that the said flexible laminar web is provided with a plurality of battens reinforcing the web in a direction transverse its length and parallel to the axis of rotation of the said at least one support member.

9. A bath incorporating a lifting mechanism according to any preceding Claim.

10. A bath and lifting mechanism combination as claimed in Claim 9, characterised in that the laminar web has releasable attachment means at a free end thereof for releasably connecting the said free end to a fixed attachment on or adjacent the bath.