GB2246397A

GB2246397A - Fluid operated actuator comprising an expandable bag

Info

Publication number: GB2246397A
Application number: GB9115299A
Authority: GB
Inventors: Roger Stewart Matthews
Original assignee: BEAKBANE Ltd
Current assignee: BEAKBANE Ltd
Priority date: 1990-07-27
Filing date: 1991-07-15
Publication date: 1992-01-29
Anticipated expiration: 2011-07-15
Also published as: GB9115299D0; EP0468336A1; GB9016589D0; GB2246397B

Description

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Title: "Expandable Bag" Description of invention

This invention relates to an expandable bag.

The use of one or more expandable bags as an actuator, is disclosed in German Patent DAS-1148874. However, such arrangements suf f er f rom the disadvantage that in some applications it is not possible accurately to control the direction along which the bag expands when fluid is introduced under pressure.

According to one aspect of the invention we provide an expandable bag adapted to be expanded in an expansion direction by the introduction of fluid into the bag under a pressure greater than the pressure externally of the bag, the bag comprising a plurality of compartments each being generally of loop configuration (as herein defined), each compartment having at least in part, flexible walls, there being passage means to permit f luid introduced into the bag at one end thereof, to flow into each of the compartments.

By "loop configuration" we mean that in plan view the compartments each present a closed figure with a centre void, the outer periphery of the closed figure being one of circular, other curved, polygonal, a combination of at least one curve and at least one straight edge.

It has been found that by providing an expandable bag comprising a plurality of loop configuration compartments suitably arranged, the direction along which the bag expands can accurately be controlled.

According to a second aspect of the invention we provide in combination, a bag according to the first aspect of the invention, and an elongate housing which contains a reaction member which is moved along the longitudinal axis of the housing by the bag as the bag expands.

The invention will now be described with reference to the accompanying drawings in which:

1 2 FIGURE 1 is a side sectional view through a bag in accordance with the invention, shown in an expanded condition, in an elongate housing, FIGURE 2 is an end sectional view of the bag only taken on the line 2-2 of Figure 1.

Referring to the drawings, an expandable bag 10 comprises a plurality of loop shaped compartments 11-20, each of which in plan view presents a generally closed f igure with a centre void, the outer periphery P of the f igure being in this example, generally circular. Each compartment.11-20 has flexible side walls 11a, 11b, which in this example comprises polyurathane coated nylon fabric, but may comprise PVC, polypropylene or other unsupported rubber or plastic film or plastic or rubber covered fabric sheet which is welded or adhered to the other side wall as indicated at 22 and 23 to provide the compartments 11-20.

Across th, centre voids of each of the loop configuration compartments 1120 extends a web 24 which comprises a double thickness of material -fixed together again by welding or adhesive.

At one end 25 of the bag 10, a relatively rigid end element 26 is provided, and at the other end 27 of the bag 10, a further generally rigid end element 28 is provided.

The element 28 is provided with a threaded stud 29 to enable the element 28 to be secured to a react-ion member R.

il The end element 26 is provided with a central opening in which is received an inlet assembly 31 comprising a boss having an inlet passageway 31a which is adapted to be connected to a source of pressurised fluid, in this example, compressed air. Alternatively the opening could be, offset from the centre axis 32.

The loop configuration compartments 11-20 are arranged so that their centres lie along the common centre axis 32, with the side walls 11a, 11b, of adjacent loop i 1 1 i i i 1 i i 3 configuration compartments 11-20 being secured together by welding and/or adhesive as desired. Extending from each of the compartments 11-20 are first passages 35,36, of a passage means, which passages 35,36, permit the flow of fluid between the compartments 11-20.

Further compartments 37-45 are defined between the webs 24 of adjacent compartments 11-20, and second passages 50 of the passage means are provided from each of the compartments 37-45 into the next adjacent further compartment, again to provide for the flow of fluid throughout the bag 10.

It can be seen that an end compartment 52 is provided between the web 24 of the compartment 20 and the element 26, there being further a passage 53 between the compartment 20 and the end or inlet compartment 52, and a yet further passage 54 is provided from the further compartment 45 and compartment 52, to permit fluid which is introduced through the inlet assembly 31 to flow into each of the loop configuration compartments 1120 and further compartments 37-45.

At the end 27 of the bag 10, a further end compartment 56 is provided between the web 24 of the compartment 11 and the end element 28, with still further passages 58 from compartment 37 into end compartment 56.

It will be appreciated that the bag 10 may be collapsed from the condition shown to a flatter condition when fluid is expelled from the bag 10, but that the bag 10 may be expanded to the condition shown by introducing fluid through the inlet assembly 31 under a pressure greater than the pressure externally of the bag, the fluid flowing into each of the loop configuration compartments 11 to 20 and further compartments 37 to 45 and end compartments 52 and 56 to expand the bag in a direction generally common with the axis 32.

4 It has been found that by providing a bag with the multi-loop configuration compartments construction described, the bag 10 will expand in the direction of axis 32 in a controlled manner whereas with a bag which has a single compartment, expansion of the bag in any particular direction is unpredictable.

With the construction shown, an expansion ratio of up to 14:1 has been achieved, although preferably a bag in accordance with the invention will be able to achieve an expansion ratio of at least 4:1 and more preferably at least 7:1.

Each of the passages 35,36,50,53,54 and 58 may have an eyelet support element as indicated in the drawings, which eyelets serve to seal the edges of the material at the periphery of the passages.

The bag 10 is shown- received within a housing H with the end element 26 fixed relative to an end wall W of the housing H and the end element 28 of the bag 10 and the reaction member R being free to move within the housing H in the direction of the axis 32. The stud 29 -may be af fixed to the reaction member R so as to move the reaction member R along the housing 11 longitudinally in the direction of centre axis 32, in the manner of a piston in a cylinder.

In the preferred embodiment, the compartments 11-20 are each generally annular in configuration and thus the housing H may be generally cylindrical. However other configurations are possible, the outer periphery P of each compartment 11-20 being circular or other curved, polygonal or any combination of at least one curve and at least one straight edge.

The bag 10 may have any number of loop configuration compartments 11-20 as desired preferably centred on the axis 32 so that the bag will expand in the direction of axis 32.

i i 1 i 1 j i i i 1 i i j 1 1 Although as described, the bag 10 comprises PVC, polypropylene or other plastic film or plastic covered fabric e.g. nylon material, the bag may be made in other materials, and constructed in another appropriate manner. For example, it is envisaged that the bag could be made by moulding at least parts of the bag to a desired configuration.

Many other modifications are possible without departing from the scope of the invention.

In the drawings, arrows show the fluid flow paths during expansion of the bag. To collapse the bag 10, fluid is withdrawn from the bag 10 via inlet assembly 31 such that fluid flow is in an opposite direction to the arrows.

The reaction member R may be used to push an item along the housing H, or to extrude a substance through an opening 0 in an end wall W2 of the housing H, although the expansion bag 10 described has many other uses as an actuator.

Although as described, the bag 10 expands in a linear direction, in another example, the bag 10 may be adapted to expand in any other direction eg. along a curve or another preset path.

The features disclosed in the foregoing description the following claims or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

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Claims

1. An expandable bag adapted to be expanded in an expansion direction by the introduction of fluid into the bag under a pressure greater than the pressure externally of the bag, the bag comprising a plurality of compartments each being generally of loop configuration (as herein defined), each compartment having at least in part, flexible walls, there being passage means to permit fluid introduced into the bag at one end thereof, to flow into each of the compartments.

2. A bag according to claim 1 wherein the loop configuration compartments are arranged so that at least prior to the bag being expanded, the centres of the loops are arranged along a common axis.

3. A bag according to claim 2 wherein the bag expands linearly, the common axis extending in the same direction as that along which the bag expands.

4. A bag according to any one of claims 1 to 3 wherein the side walls of the loop configuration compartments are connected together to form the bag.

5. A bag according to any one of claims 1 to 3 wherein adjacent loop shaped compartments share, at least in part, side walls.

6. A bag according to any one of claims 1 to 5 wherein a web extends across each of the centre voids of the webs of the loop configuration compartments.

7. A bag according to any one of claims 3 to 6 where appendant to claim 3, wherein the webs each extend TI 1 i 1 1 1 7 generally parallel to one another in a direction transverse to the common axis along which the bag expands.

8. A bag according to claim 6 or claim 7 wherein further compartments are defined between the webs of adjacent loop configuration compartments, the passage means comprising first passages between the loop configuration compartments and the further compartments, and second passages between adjacent further compartments.

9. A bag according to claim 8 wherein one first passage opens from each loop configuration compartment into a further compartment at one side of the web extending across the respective centre void of the loop shaped compartment and another first passage opens from each of the loop configuration compartments into a further compartment at the other side of the web extending across the respective centre void of the loop shaped compartment.

10. A bag according to claim 9 wherein the one and another first passages are located at opposite positions of the respective loop configuration compartments.

11. A bag according to any one of claims 1 to 10 wherein the loop configuration compartments are generally annular in plan view.

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12. A bag according to claim 11 wherein dependant claim 6 wherein the webs are circular.

13. A bag according to claim 11 or claim 12 wherein the bag at least when expanded, is generally of cylindrical outer configuration.

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14. A bag according to any one of the preceding claims wherein the means which permit of the introduction of f luid into the bag at the one end thereof, comprises an inlet assembly having a rigid element secured to the bag, the rigid element including an inlet passageway therethrough.

15. A bag according to claim 14 wherein the inlet passageway extends into an inlet compartment of the bag f rom where f luid may pass into the loop conf iguration compartments and where appropriate, the further compartments, of the bag.

16. A bag according to any one of the preceding claims wherein the bag is made of polyurathane coated nylon f abric or PVC, polypropylene, or another unsupported rubber or piastic film or plastic or rubber covered fabric.

17. An expandable bag substantially as hereinbef ore described with reference to and as shown in the accompanying drawings.

18. In combination, a bag according to any one of claims 1 to 17, and an elongate housing which contains a reaction member which is moved along the longitudinal axis of the housing as the bag expands.

19. A combination according to claim 18 wherein the bag is contained within the elongate housing with the one end of the bag at which fluid is introduced into the bag being fixed relative to the housing.

20. A combination according to claim 18 or claiia 19 wherein the bag is expandable in a direction parallel to the longitudinal axis of the housing.

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21. A combination according to claim 20 wherein the housing is generally cylindrical and the bag is expandable in the direction of the cylindrical axis of the housing.

22. A combination according to any one of claims 18 to 21 wherein the reaction member is moved in the manner of a piston within the housing.

23. A combination of an expandable bag and an elongate housing substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

24. Any novel feature or novel combination of features herein defined and/or shown in the accompanying drawings.

Published 1992 at The Patent Office. Concept House. Cardiff Road. Newport. Gwent NP9 I RH. Further copies maybe obtained front Sales Branch. Unit 6. Nine Mile Point. Cwmfelinfach. Cross Keys, Newport. NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray. Keni-