GB2166495A - Lifting bags - Google Patents

Abstract

A lifting bag suitable for use in a lift is provided which comprises a pair of generally tapered envelopes (1, 2) sealingly joined together at the smaller ends thereof (3, 4) each of the larger ends (6, 7) being joined to respective substantially rigid members (8, 9), the bag being adapted to be inflated or deflated by fluid pressurising means (12) such that the large ends (6, 7) are movable relative to each other along an axis (X) on which each envelope (1, 2) remains generally concentric. <IMAGE>

Description

SPECIFICATION Improvements in or relating to lifting bags This invention relates to lifting bags of the type within which a fluid under pressure is introduced such that the bag can raise or lower a load.

Lifting bags of the type described find particular application in the field of general purpose lifts such as those that require transportation of a load from one floor to another, as opposed to those lifts which are required to carry loads to and from a relatively great height, such as in a multi-storey building, in which case the more conventional motordriven pulley and cable lift is used instead.

One known lifting bag comprises a convolute envelope shaped like a concertina which, in use, is placed beneath the floor of a lift such that by varying the pressure within the bag a load can be raised or lowered safely.

Because the bag is shaped like a concertina, when deflated the side-walls of the bag are constrained to remain in a position co-axial to the central vertical axis of the bag and when fully deflated, the bag still retains a concertinalike shape. It will be appreciated that if the bag were provided with smooth walls instead of concertina-shaped walls, such smooth walls would not be constrained to remain in any particular configuration when the bag os deflated and thus it could become lop-sided within the lift structure and could hence become entangled and/or work inefficiently or erractically when re-inflated.

Whilst it would be desirable to use a smooth-sided bag because of simplicity of manufacture and low cost, this is not practical for the reasons aforesaid, but on the other hand use of a concertina-shaped bag has the disadvantage in that such bags are difficult to manufacture and can be relatively expensive.

> It is an object of the present invention to pròside a lifting bag which is able to perform the functions required of the concertina-like bag, but which is more easily manufactured and at less cost.

According to the invention there is provided a lifting bag for a lift, the bag comprising a pair of generally tapered envelopes sealingly joined together at the smaller ends thereof, the bag being adapted to be inflated or deflated by fluid pressurising means such that the larger ends of each envelope are movable relative to each other along an axis on which each envelope remains generally concentric.

Conveniently, each tapered envelope may be frusto-conical such that when deflated each envelope defines an annulus. Such an arrangement allows the smaller diameter end of each envelope to fold inside the larger diameter end.

Conveniently, the larger end of each envelope may be connected to a respective substantially rigid member.

Each lifting bag may be made from any suitably imperforate material such as polyurethane-proofed nylon and each envelope can be joined to a respective envelope and/or rigid member by stitching, moulding, gluing or even by welding such as by using radio frequency waves. Alternatively, the envelopes of each bag may be integral with each other, in which case the need for subsequently joining each envelope together can be dispensed with.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a sectional schematic front elevation of a lifting bag in its fully inflated condition.

Figures 2a, 2b, 2c and 2d show the bag of Fig. 1 in various stages of deflation.

Figure 3 is a perspective view of a lifting bag installed within a lift.

Referring firstly to Fig. 1 of the drawings, a lifting bag according to this embodiment of the invention comprises a pair of generally frusto-conical envelopes 1, 2 sealingly joined together at the smaller diameter ends 3, 4 by a resilient strip 5. Each larger diameter end 6, 7 is joined to a respective circular rigid member 8, 9 and the envelopes 1, 2 define an enclosure 10.

On the lower rigid member 9 is secured a one-way valve 11 connected to a pressurised fluid reservoir of air shown generally at 12 by which the bag can be inflated. An exhaust valve 13 is also provided on the rigid member 9 and is operable to allow the escape of air from the bag when required.

In operation, air is introduced from the air reservoir 12 into the enclosure 10 via the inlet valve 11 whereupon the larger ends of the envelopes and hence the rigid members 8, 9 are moved relatively apart along a central vertical axis, shown at "X", until the position of Fig. 1 is assumed. When deflation of the bag is required, the exhaust valve 13 is activated and the rigid member 8 moves back towards the rigid member 9, again along the vertical axis, assuming the positions shown in Figs.

2a, b, c, & d, where it will be noted that each of the envelopes 1, 2 remain in a generally concentric position relative to the vertical axis of the bag when the bag is being deflated.

Referring now to Fig. 3 of the drawings, there is shown a generally conventional lift 14 fixed adjacent to a door step 15 but in which lift a bag according to the invention has been incorporated. The lift comprises a generally rectilinear, rigid metal base frame 16 from opposite sides of which extend upwardly a pair of guide panels 17, 18. Adjacent each guide panel 17, 18 is slidably mounted a scissor mechanism 20, 21 arranged to facilitate planar upward and downward movement of the platform 19, without the platform 19 tilting, in a conventional manner. Beneath the platform 19 centrally within the base frame 16 is disposed a lifting bag 22 according to the invention and, as previously described, is operable to raise and lower the platform 19 as required such that an occupant thereof can be transported safely.When deflated, the bag 22 assumes a position corresponding to that shown in Fig. 2.

It will be appreciated that the invention is not limited to the embodiment described above and instead of a single bag being utilised, a series of bags connected end-to-end may be suitably arranged together, depending on the type of lifting operation required.

The fluid may conveniently comprise air but it is envisaged that in some applications other fluids such as liquids could be used instead.

The actual dimensions of the lifting bag or bags can be varied to suit the particular application required. In the embodiment described, the extended length of the first envelope 1 was 17 inches and the extended length of the second envelope 2 was 23 inches, making a total extended length of the bag of 40 inches.

Also, the larger end of the first envelope has a diameter slightly smaller than the larger end of the second envelope. Although it would be possible to use a pair of envelopes, each having identical configurations and dimensions, nevertheless it is found in practice that it is preferable for one of the envelopes to be shorter than the other so that the larger of the envelopes is guided by the smaller of the envelopes into a position1 in which it is concentric with the vertical central axis the bag.

Claims (7)

1. A lifting bag for a lift, the bag comprising a pair of generally tapered envelopes sealingly joined together at the smaller ends thereof, the bag being adapted to be inflated or deflated by fluid pressurising means such that the larger ends of each envelope are movable relative to each other along an axis on which each envelope remains generally concentric.

2. A bag according to claim 1 in which each tapered envelope is frusto-conical such that when deflated each envelope defines an annulus.

3. A bag according to claim 1 or claim 2 in which the larger end of each envelope is connected to a respective substantially rigid member.

4. A bag according to any preceding claim which the smaller ends of each envelope are joined together by a resilient strip.

5. A bag according to any one of claims 1 to 3 in which the envelopes are pre-formed integrally with each other.

6. A lifting bag substantially as hereinbefore described with reference to and as shown in Figs. 1 and 2 of the accompanying drawings.

7. A lift including a lifting bag substantially as hereinbefore described with reference to and as shown in Fig. 3 of the accompanying drawings.