GB2409811A - Battery-operated bath lift - Google Patents

Abstract

A bath lift (1) comprising a chassis (5) for resting, in use, at the bottom of a bath, the chassis supporting a moveably mounted seat (8), the seat being moveable between raised and lowered positions by a battery-operating lifting mechanism (11), the lifting mechanism including an electric motor (15) having a drive shaft (16), a worm gear (17) fixed to the drive shaft and in mesh with a spur gear (18) mounted for rotation with a driven shaft (19), the driven shaft driving either directly or indirectly a threaded end of a linearly moveable actuating arm (14) for raising and lowering the seat, characterised in that the driven shaft includes at one end means (22) for connection to a handle (23) for rotating the driven shaft independently of the electric motor, and that the pitch of the worm gear and hence the spur gear is such as to allow the driven shaft to be rotatable by the handle in substitution for the electric motor.

Description

240981 1 Improvements in and relating to Batterv-Operated Bath Lifts This

invention relates to battery-operated bath lifts of the type which utilise a chassis adapted to rest on the bottom of a bath and a slideably supported seat adapted to be moveable between respective raised and lowered positions through the use of an electric motor and associated seat-lifting mechanism actuated thereby.

Battery-operated bath lifts are particularly convenient because they are generally quite lightweight and can therefore be lifted into and out of a bath by even a moderately disabled person, the associated rechargeable battery pack conveniently being stored separately as part of e.g. the remote operating mechanism. A problem with this arrangement, however, is that because it is reliant upon the correct functioning of a number of parts including the electric motor, the battery and attendant electronic circuitry, a failure in any of these when the bath lift is in use presents a substantial problem to the user thereof.

This can mean a third party having to call out emergency services, typically the medical and/or police services followed by the fire service in order to extract the user of the bath lift from the bath. Apart from the embarrassment caused this is also time consuming and expensive in terms of manpower, and potentially 2 0 health or even life threatening.

The foregoing problem has been alleviated in part by the incorporation in battery-operated bath lifts of electrically-operated safety override features whereby, for example, a failure in the primary operating circuitry can be automatically overridden by secondary operating circuitry to ensure that the electric motor is at least able to raise the seat and hence a user of the bath lift sufficient for the user to be extracted from the bath, with or without third party assistance. However, this type of system is still necessarily dependent upon correct functioning of e.g. the electric motor and/or the rechargeable battery, whereas a failure in either of these means that the electrically-operable override system cannot achieve its intended objective.

The present invention is derived from the realisation that a manual override system would be preferable and in particular by the surprising realisation that a drive train which includes a speed reduction spur gear rotatably connected to a shaft driven by the primary drive shaft of the electric motor by being in mesh with a worm gear fixed thereto can be driven reversibly by e.g. a detachable handle if the pitch of the worm gear and hence the spur gear is sufficiently acute, such as being above about 18 to 35 from perpendicular to the major axis of the drive shaft of the electric motor.

According to the invention there is therefore provided a bath lift comprising a chassis for resting, in use, at the bottom of a bath, the chassis supporting a moveably mounted seat, the seat being moveable between raised and lowered positions by a battery-operating lifting mechanism, the lifting mechanism comprising or including an electric motor having a drive shaft, a worm gear fixed to the drive shaft and in mesh with a spur gear mounted for rotation with a driven shaft, the driven shaft driving either directly or indirectly a threaded end of a linearly moveable actuating arm for raising and lowering the seat, characterized in that the driven shaft includes at one end means for connection to a handle for rotating the driven shaft independently of the electric motor, and that the pitch of the worm gear and hence the spur gear is such as to allow the driven shaft to be rotatable by the handle in substitution for the electric motor.

Preferably, the pitch of the worm gear is greater than about 22 from perpendicular to the major axis of the electric motor drive shaft and most preferably is within the range of about 18 to 35 Conveniently, the handle is stepped and includes at its end remote from its hand-engaging end a rectilinear, such as square, aperture receivable on a correspondingly-shaped end of the driven shaft such that upon failure of any of the electrical or mechanical components of the lifting mechanism, attendant circuitry or the battery the handle may be simply mounted onto the end of the driven shaft and rotated in a required direction to raise or lower the seat.

Whilst it is understood that any drive train is theoretically reversible it will be apparent that in the real world frictional losses, including those attributable to the viscosity of lubricants mean that, in general, the greater the ratio of speed reduction the harder it is to provide rotation from the usually driven end of a speed reduction mechanism. Heretofore, manufacturers of bath lifts which utilise threaded shafts and associated speed reduction worm wheels and spur gears cannot expect such to operate reversibly, whereas the present invention 2 0 has recognized that within the limits dictated by actual frictional losses throughout the drive train this is, in fact, possible and represents a simple and elegant solution to a problem that has heretofore only been partly solved by the adoption of an electrical/electronic override capability. ! '

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of a conventional bath lift, Figure 2a is part exploded view of part of the bath lift of Figure 1 but incorporating a manual override facility in accordance with the invention, and Figure 2b is an enlarged detailed view of the manual override facility of Figure 2a.

Figure 1 shows an exploded view of a bath lift shown generally at 1 and attendant rechargeable battery 2 insertable within a docking end of a control panel 3 itself releasably securable to a cradle 4 which may be mounted, for example, on a wall surface of a bathroom next to a bath (not shown).

The bath lift 1 comprises a chassis 5 in the form of a yoke and associated suction feet 6 by which the chassis 5 may rest on the bottom of the bath.

Extending from the chassis 5 are a pair of guide pillars 7 onto which is slideably mountable a seat 8 having a backrest 8a from the rear of which extend a pair of guide collars 9 dimensioned to be received on the guide pillars 7. A mounting spigot 10 also extends from a central, upper region of the backrest 8a and onto which may be mounted by bolts (not shown) the upper end 11a of a lift actuating mechanism shown generally at 11, the lower end 11b being receivable within a 2 0 correspondingly-shaped recess in an upper, rear portion 5a of the chassis 5.

The upper and lower ends 1 1 a, 11 b are axially moveable relative to each other via an electric motor and gear assemble (not shown) contained within a housing 11c to thereby raise and lower the seat 8 in a conventional manner as described below with reference to Figures 2a and 2b.

Extendable side panels 12 are provided on respectively opposite sides of the seat 8 in order to allow a user of the bath lift 1 to slide onto and off the seat 8 when in its raised position relative to the chassis 5.

In operation, the control panel 3 is electrically connected to the lift actuating mechanism 11 by wires (not shown) and by virtue of the upper end 11 a of the actuating mechanism 11 being attached to the slideably mounted seat 8 via the centrally disposed spigot 10 the lift actuating mechanism 11 is able to raise and lower the seat 8 as desired when the apparatus is functioning correctly. However, as will be appreciated, when it is not, such as by the battery 2 being faulty, or by the electric motor (not shown) within the housing 1 1 c being faulty, or by any of the attendant electrical circuitry being faulty the bath lift 1 is unable to function correctly until the fault is rectified.

In Figure 2a there is shown a part exploded perspective view of the bath lift of Figure 1 but modified in accordance with the invention, in which identical parts are numbered accordingly. As will be seen, the seat 8 is shown slideably mounted on the guide pillars 7 extending from the chassis 5 and the lift actuating mechanism 11 is secured at its upper end 11a to the centrally disposed spigot 10, the lower end 11b (not shown) being received within the recess 5a at the rear of the chassis 5.

The lift actuating mechanism 11 includes a cylindrical strut 13 within which is received a linearly extendable actuating rod 14 by which the overall length of the strut 13 may be varied to correspond with the required height of the seat 8 as it is being raised or lowered. This is achieved by means of internally threaded parts (not shown) which when rotated in one direction shorten the overall length of the lift actuating member 11, and lengthen it when rotated in the opposite direction in a conventional manner.

As will be seen more clearly with reference to Figure 2b, rotation is achieved by means of internally disposed bevel gears (not shown) which transmit rotation about one axis to rotation in a direction normal thereto. In turn, this is achieved by means of a battery-operated electric motor 15 from which extends a drive shaft 16 onto which is fixed for rotation therewith a worm gear 17 in mesh with a spur gear 18 fixed for rotation on a driven shaft 19. The driven end 20 of the driven shaft 19 includes a flattened region 20a by which it may be keyed into a correspondingly shaped aperture in the first of a pair of bevel gears (not shown) within a gear housing 21 for converting rotational movement from the driven shaft 19 about its major axis to rotation transverse thereto about the major axis of the strut 13 and associated actuating rod 14 to thereby transmit rotational movement to the threaded portions therewithin (not shown) and vary the overall length of the lift actuating mechanism 11.

Thus far the arrangement is conventional, but in accordance with the invention the driven shaft 19 extends outwardly from the spur gear 18 through a cover (not shown) for the motor 15 and attendant drive train and terminates in a square end 22 onto which may be releasably fitted a handle 23, by which the driven shaft 19 may be rotated independently of the motor 15, drive shaft 16 and attendant gearing 17, 18. This simple and elegant expedient means that provided the pitch of the worm gear 17 and associated spur gear 18 is not less than about 18 and is typically about 22 transverse to the axis of rotation it is therefore possible to drive the driven shaft 19 manually via the handle 23 in the : l l event of failure of the motor 15, or any associated electrical components, or the battery 2. Whilst it will be understood that the handle 23 cannot easily be operated by a person occupying the seat 8, nevertheless it can still be operated by e.g. a family member without the necessity of calling in outside help, therefore obviating or alleviating attendant embarrassment and/or manpower required.

Although the invention envisages the use of a manual override by, effectively, lengthening the driven shaft 19 at its end remote from the end it drives, nevertheless it will be appreciated that the driven shaft may instead be extended in the opposite direction through the use of a suitable aperture through e.g. a bevel gear which it drives upon being driven by the drive shaft 16 and attendant gearing 17, 18. Similarly, although bevel gears are preferred to transfer rotational movement through 90 it will be understood that, depending upon the configuration of the motor relative to threaded parts required to be rotated, other types of gears may be used or may even be dispensed with if the driven shaft 19 drivingly engages directly with a threaded component providing the required linear movement to raise and lower the seat 8. Other modifications and variations may also be made without departing from the spirit or scope of the invention.

Claims (6)

1. Claims 1. A bath lift comprising a chassis for resting, in use, at the

   bottom of a bath, the chassis supporting a moveably mounted seat, the seat being moveable between raised and lowered positions by a battery-operating lifting mechanism, the lifting mechanism comprising or including an electric motor having a drive shaft, a worm gear fixed to the drive shaft and in mesh with a spur gear mounted for rotation with a driven shaft, the driven shaft driving either directly or indirectly a threaded end of a linearly moveable actuating arm for raising and lowering the seat, characterized in that the driven shaft includes at one end means for connection to a handle for rotating the driven shaft independently of the electric motor, and that the pitch of the worm gear and hence the spur gear is such as to allow the driven shaft to be rotatable by the handle in substitution for the electric motor.
2. 2. A bath lift according to claim 1 further characterized in that the pitch of the worm gear is greater than about 22 from perpendicular to the major axis of the electric motor drive shaft.
3. 3. A bath lift according to claim 1 further characterized in that the pitch of the worm gear is within the range of about 18 to 35 .
4. 4. A bath lift according to any preceding claim further characterized in that the handle is stepped and includes at its end remote from its handengaging end a rectilinear, such as square, aperture receivable on a correspondingly-shaped end of the driven shaft such that upon failure of any of the electrical or mechanical components of the lifting mechanism, attendant circuitry or the battery the handle may be simply mounted onto the end of the driven shaft and rotated in a required direction to raise or lower the seat.
5. 5. A bath lift substantially hereinbefore described with reference to the drawings.
6. 6. A bath lift actuator mechanism substantially hereinbefore described with reference to the drawings.