GB2238293A - Lifting apparatus - Google Patents

Abstract

A lifting assembly for disabled or handicapped persons comprises a base 13 which forms a bottom transverse member of a lower lifting unit 14, and a platform 15 which forms an upper transverse member of an upper lifting unit 16, which units 14 and 16 are united by a common intermediate transverse partition member 17 parallel with the base and platform. Each unit 14 and 16 has a flexible bellows 18 which serves as thrust means and provides a peripheral wall around a stabilising mechanism 19. Inflation and deflation of the units 14 and 16 is manually controlled via control means 12 which is responsive to sensors 31 and 32 associated with respective lifting units to ensure consecutive inflation and deflation of the units 14 and 16 to give stable lifting and lowering of the platform 15. The platform may be tiltable by the upper lifting unit (Fig 4). <IMAGE>

Description

LIFTING APPARATUS Lifting apparatus, for supporting, raising and lowering of disabled or handicapped persons.

In our prior Patent Specification GB 2166415B there is disclosed lifting apparatus which includes a lifting unit, comprising a base, a platform above the base, thrust means to raise the platform relative to the base, and a mechanical stabilising means connecting the platform and base in parallel.

GB 2166415B discloses that several such units may be arranged in a stack or row and be connected, e.g. by self-sealing fluid couplings, to operate sequentially or in unison. However, it has been found that when two or more such units are stacked the problems of stabilisation of the uppermost platform are compounded, (even though the stabilising means is constructed to reduce the problem of movements of the platform out of parallel with the base, e.g. to suppress pitch, roll and yaw movements which could upset or disturb a person supported upon the platform) because the stabilising means, being extensible, incorporates bearings and sliders to permit movement of the parts of the stabilising means.Although stabilisation can be improved by reducing bearing and slider clearances or by increasing the pre-loading of the bearings and sliders, such expedients are limited by the consequential increase in friction in the stabilising means becoming sufficient to inhibit smooth operation of the unit. Smooth operation is also essential to avoid upsetting or disturbing a person supported upon the apparatus.

An object of the invention is to enable such problems to be reduced.

In general, the present invention provides lifting apparatus comprising superimposed extensible lifting units disposed between a base and an upper part to raise and lower the upper part relative to the base, manually operable control means to control the extension and retraction of said units, wherein at least one of said units incorporates an extensible stabilising mechanism to maintain a lower portion of the unit substantially parallel to an upper portion of the unit, and wherein said control means comprises a sensor associated with said one of said units to inhibit extension of the other or others of said units unless or until said one unit is in or reaches an extended condition in which further extension is prevented mechanically by the stabilising mechanism abutting stops in said one unit.

According to a first preferred form of the present invention there is provided lifting apparatus comprising a plurality of pneumatically extensible units including at least an upper unit and a lower unit; and comprising pneumatic thrust means to extend said units from respective retracted conditions to extended conditions to raise an upper part relative to a base, and control means manually operable to actuate the thrust means; wherein the control means comprises a first sensor associated with the lower unit to inhibit pneumatic pressurisation of the upper unit until or unless the lower unit reaches or is held in its extended condition in which further extension is mechanically prevented by a stabilising mechanism abutting stops in the lower unit, and a second sensor associated with the upper unit to inhibit retraction of the lower unit from the extended condition unless the upper unit is substantially depressurised.

This first form of the apparatus is particularly suitable for use as a lifting and tilting seat in which the lower unit is stabilised and provides most of the overall lift, whilst the upper unit is unstabilised and serves as an inflatable device, such as a cushion, which provides a tilting function as well as some lift.

According to a second preferred form of the present invention there is provided lifting apparatus comprising at least a first extensible unit and a second extensible unit between a base and an upper part, thrust means to extend said units from respective retracted conditions to extended conditions, a stabilising mechanism in each unit and control means manually operable to actuate the thrust means; wherein the control means comprises a first sensor associated with the first unit to inhibit extension of the second unit until or unless the first unit reaches or is held in its extended condition in which further extension is mechanically prevented by the stabilising mechanism abutting stops in the first unit, and a second sensor associated with the second unit to inhibit retraction of the first unit from the extended condition unless the second unit is in its retracted condition in which further retraction is prevented mechanically by stops.

This second form of the apparatus is particularly suitable for meeting high lift fully stabilised requirements, e.g. where it is required to provide vertical movement of a person through a metre or more by means of apparatus having a plan area of less than one square metre, e.g. about half a square metre.

An intermediate lifting unit or units, of stabilised form, may be interposed between the upper and lower units; and respective sensors, for determining retraction and extension of the intermediate units, may be provided, so that only one lifting unit may be varied in height at any given instant.

The lifting units may be constructed substantially as disclosed in GB 2166415B with the platform of one unit being connected to and supporting the base of the superimposed unit, but the units are preferably integrated by employing a single common transverse member or rigid partition therebetween, instead of the connecting together of the platform and the superimposed base.

The upper part is preferably provided by a platform of the upper unit or uppermost of the units, and the base is preferably a lower part of the lower unit or lowermost of the units.

The thrust means preferably comprises pneumatically inflatable bellows forming a flexible peripheral wall of each unit, the stabilising mechanism being surrounded by said wall.

The control means preferably includes an override control which is actuable to permit a pressurisation of one or more of the units, especially to make good any pressure loss in the lower unit, so that leakage can not cause an interlocked state.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings, wherein FIGURE 1 shows a schematic electro-pneumatic control circuit diagram of control means in conjunction with lifting units of apparatus of the invention, FIGURE 2 is a part sectional view of sensors and a valve unit of the control means, FIGURE 3 is a part sectional view of the lifting units of the apparatus showing the installation alternative sensors; and FIGURE 4 shows an alternative assembly of lifting units.

The lifting apparatus includes a lifting assembly 10, a compressor 11 and control means 12.

The lifting assembly 10 shown in FIGURE 1 comprises a base 13 which forms a bottom transverse member of a lower lifting unit 14, and a platform 15 which forms an upper transverse member of an upper lifting unit 16, which units 14 and 16 are united by a common intermediate transverse partition member 17 parallel with the base and platform. Each unit 14 and 16 has a flexible bellows 18 which serves as thrust means and provides a peripheral wall around a stabilising mechanism 19 in the unit, as described in GB 2166415B. Both stabilising mechanism act on the partition 17 to maintain the base and platform parallel thereto.

Each unit 14 or 16 is connected, via a respective pneumatic line 24 or 26, to a respective control valve 25 or 27 of the control means 12, which valves 25 and 27 are connected to a supply line 21, incorporating a non-return valve 22, by a main line 23 which is further connected to an exhaust valve 28 and an overload-pressure switch 29 of the control means. The supply line 21 is connected to the compressor 11.

The control means in this embodiment is designed to be situated remote from the lifting assembly which is in turn constructed for use in condition wherein it is exposed to water, e.g. to be located in a bath by means of suckers 30 on the base 13, or for use as part of a wheelchair for outdoor use. To this end the pneumatic lines 24 and 26 are detachable from the lifting assembly and are connected in the control means to respective sensors 32 and 31 in the form of pneumatically actuated electrical switches in an electrical control circuit of the control means.

Said circuit includes a fused charging input 40, to a rechargeable battery 41 which supplies power to the compressor 11 via a combined master switch and circuit breaker 42 and a relay 43; and all thereof may be included in a portable unit which is separable from the remainder of the control means e.g. by means of separable electrical and pneumatic connectors 44 and 45. Said remainder may be constructed as a unit separable from the lines 24 and 26.

The relay is connectable to the battery via a line 46 to one pole a manually operable up/down selector switch 47, and by a further line 48 controlled by the supply pressure actuated overload switch 29. The switch 47 has a second pole which supplies power to the solenoid of the exhaust valve 28. The switch 47 is biased to a normal off position from which it is manually displaceable to close on either pole and is ganged with a similarly biased switch 47A having two poles both connected to a manually operable bistable upper/lower unit selector switch 49.The actuating solenoid of the valve 25 is connected by a line 51 between one pole of the switch 49 and the sensor 31 which is biased to a normal closed position and to open when a predetermined low pressure is exceeded in line 26 to the upper unit 16; and the solenoid of valve 27 is connected by a line 52 between the other pole of switch 49 and the sensor 32 which is biased to a normal open position and to close only when a predetermined high pressure is exceeded in line 24 to the lower unit 14. The sensor 31 is shunted by an override switch 53 which is biased to an open condition and is manually closable against said bias.

The sensors and control valves may be assembled together as shown in FIGURE 2.

The predetermined high pressure is determined to ensure that the pressure in the lower unit 14 is sufficient to hold the stabilising mechanism at full extension against stops in the unit 14 when any load up to a predetermined maximum load is applied to the platform, and to allow a safety margin. For example, if the predetermined maximum safe working load is 150 kilogrammes the high pressure is determined so that the stabilising mechanism is held securely at full extension when the a load of about 200 kilogrammes is applied to the platform, i.e. is determined to provide a safety margin of about 50 kilogrammes or some 30% of the safe working load. The safety margin of at least 10% is recommended.

The predetermined low pressure is set only slightly above atmospheric pressure, so that the stabilising mechanism in the upper unit is fully retracted against stops in the upper unit, preferably when subjected only to the load provided by the platform itself, when the pressure in the upper unit falls to or is at said low pressure.

Instead of employing pneumatic pressure responsive sensors, mechanically actuated sensors in the form of micro-switches 31A and 32A may be employed in the lifting assembly as indicated diagrammatically in FIGURE 3, which shows a composite of parts of lifting units, including parts of the thrust means and stabilising mechanisms. As described in GB 2166415B, to which reference should be made for further details, the stabilising mechanism 19 comprises two pivotally interconnected linkage devices 60,61 connected upper and lower pivotal connections 62,63 to upper and lower transverse members (such as the platform and base) and by sliders 64,65 movable in guides 66,67 secured to the transverse members so as to be linearly movable on the guides between fixed limits defined by up stops 68 fixed relative to the guides 66,67.In the circuit shown in FIGURE 1 the switch 31A is substituted for switch 31 and is mounted on or adjacent to one of the down stops 69 in the upper unit 16, and switch 32A is substituted for switch 32 and is mounted on or adjacent to one of the up stops 68 in the lower unit 14.

In embodiments wherein the lifting assembly comprises three lifting units, pressurisation and depressurisation of the intermediate unit is preferably controlled by a further control valve supplied via the main line, the further valve being controlled by a line incorporating both sensors 31 or 31A and 32 or 32A; and the intermediate lifting unit and is preferably supplied via or provided with further high and low pressure or position sensitive sensors which are connected into lines 52 and 51 instead of the sensors 31,31A and 32,32A so that during lifting the units can only be pressurised in sequence starting with the lowermost unit, and be depressurised, for lowering, in sequence starting with the uppermost unit.

Under certain circumstances it may be preferable to re-arrange the control means to ensure that the sequences are reversed, so that pressurisation commences with the upper or uppermost lifting unit, e.g. to provide an effect achievable by simple inversion of the lifting assembly shown in FIGURE 1; and it is of course possible to vary the control means for a three unit lifting assembly to give an alternative pressurisation sequence starting with the intermediate unit with a depressurisation sequence finishing with the intermediate unit. However, such reverse and alternative sequences are unsuited to certain applications such as in the further embodiment shown in FIGURE 4.

In the foregoing examples of the invention both or all three lifting units are stabilised by respective stabilising mechanisms. The mechanisms may be of any suitable form which becomes substantially rigid when extended or retracted to maximum or minimum positions in which further extension or retraction is prevented by stops provided in the mechanisms or fixed on parts of the units e.g. to be engageable by the mechanisms. Whilst the stabilising mechanisms described in GB 2166415B comprises two linkage devices 60 and 61, one or more of the units 14 and 16 (and the intermediate unit if provided) may incorporate a single such linkage device modified to utilise the connections 62,63 and sliders 64,65, so that lifting assemblies having odd or even numbers of linkage devices can be constructed.

Furthermore, the upper or uppermost lifting unit need not be stabilised and may be constructed to provide other functions, e.g. tilting, as is now described with reference to FIGURE 4, which shows a lifting assembly which utilises the control means shown in FIGURE 1 and comprises the lower lifting unit 14 and a lift and tilt upper unit 70.

The unit 70 does not have an internal stabilising mechanism between the platform 15A and the transverse partition member 17, and the platform 15A is provided at two or more of its sides with hinge connectors 71 which are selectively connectable to the member 17 to allow pressurisation of the thrust means 72 (also of bellows form) to be employed to lift and tilt the platform about a selected one of two or more axes parallel to the sides of the platform. Alternatively, if only one tilting direction is required the platform and partition member may be connected by a hinge at the front side of the platform, e.g. where the apparatus is employed in a wheelchair, to assist a person being stood upright.

The platform 15 or 15A may support a seat or cushion, and may be adapted to receive flank panels as described in GB 2166415B. Alternatively, especially in the FIGURE 4 embodiment, the platform and/or partition member may accommodate slidably therein a flank panel which can be drawn out to bridge a gap between the lifting assembly and a seat or bed to which a person is to be transferred.

The invention is not confined to details of the foregoing examples and many variations and modifications are possible within the scope of the invention which includes lifting apparatus, a lifting and tilting assembly and control means incorporating any novel part or feature or combination thereof disclosed herein or in the drawings, and functional equivalents thereof.

For example, the upper/lower selector switch and solenoid actuated control valves may be replaced by a manually operated selector valve arrangement having sensor actuated detents or other means to inhibit either out of sequence selection of pressurisation and depressurisation operations, or pressurisation or depressurisation in response to out of sequence selections.

Instead of employing separate down stops 69, link devices 60,61 may retract to a limited condition inwhich parts thereof serve mutually as stops to prevent further retraction.

Claims (12)

1. Lifting apparatus comprising superimposed extensible lifting units disposed between a base and an upper part to raise and lower the upper part relative to the base, manually operable control means to control the extension and retraction of said units, wherein at least one of said units incorporates an extensible stabilising mechanism to maintain a lower portion of the unit substantially parallel to an upper portion of the unit, and wherein said control means comprises a sensor associated with said one of said units to inhibit extension of the other or others of said units unless or until said one unit is in or reaches an extended condition in which further extension is prevented mechanically by the stabilising mechanism abutting stops in said one unit.

2. Lifting apparatus comprising a plurality of pneumatically extensible units including at least an upper unit and a lower unit; and comprising pneumatic thrust means to extend said units from respective retracted conditions to extended conditions to raise an upper part relative to a base, and control means manually operable to actuate the thrust means; wherein the control means comprises a first sensor associated with the lower unit to inhibit pneumatic pressurisation of the upper unit until or unless the lower unit reaches or is held in its extended condition in which further extension is mechanically prevented by a stabilising mechanism abutting stops in the lower unit, and a second sensor associated with the upper unit to inhibit retraction of the lower unit from the extended condition unless the upper unit is substantially depressurised.

3. Apparatus as claimed in Claim 2 arranged for use as a lifting and tilting seat in which the lower unit is stabilised and provides most of the overall lift, whilst the upper unit is unstabilised and serves as an inflatable device, such as a cushion, which provides a tilting function as well as some lift.

4. Lifting apparatus comprising at least a first extensible unit and a second extensible unit between a base and an upper part, thrust means to extend said units from respective retracted conditions to extended conditions, a stabilising mechanism in each unit and control means manually operable to actuate the thrust means; wherein the control means comprises a first sensor associated with the first unit to inhibit extension of the second unit until or unless the first unit reaches or is held in its extended condition in which further extension is mechanically prevented by the stabilising mechanism abutting stops in the first unit, and a second sensor associated with the second unit to inhibit retraction of the first unit from the extended condition unless the second unit is in its retracted condition in which further retraction is prevented mechanically by stops.

5. Apparatus as claimed in Claim 4 constructed and arranged to provide a vertical movement of at least one metre and having a plan area of less than one square metre.

6. Apparatus as claimed in any preceding claim wherein an intermediate lifting unit or units, of stabilised form is interposed between the upper and lower unit or between the first and second units.

7. Apparatus as claimed in any preceding claim wherein respective sensors, for determining retraction and extension of the intermediate unit or units are provided so that only one lifting unit may be varied in height at any given instant.

8. Apparatus as claimed in any preceding claim wherein units are integrated by employing a single common transverse member or rigid partition therebetween.

9. Apparatus as claimed in Claim 8 claim wherein the upper part is provided by a platform of the upper unit or uppermost of the units, and the base is a lower part of the lower unit or lowermost of the units.

10. Apparatus as claimed in any preceding claim wherein the thrust means comprises pneumatically inflatable bellows forming a flexible peripheral wall of each unit, the stabilising mechanism being surrounded by said wall.

11. Apparatus as claimed in any preceding claim wherein the control means includes an override control which is actuable to permit a pressurisation of one or more of the units.

12. Apparatus substantially as hereinbefore described with reference to FIGURE 1; FIGURES 1 and 2; or FIGURE 1 as modified by FIGURE 3 or FIGURE 4 of the accompanying drawings.