Paying out and/or hauling in a flexible elongate tensile member

Abstract

 A component 10 has a bore 12 through which tensile member (e.g. a cable) 11 extends with a clearance 13, which clearance 13 is at least partly filled with a fluid 14 (e.g. a silicone liquid). As the cable moves through the component 10 a shear force is generated to create a desired resistance to movement of the cable 11.

Description

[0001] This invention relates to apparatus for controlling the paying out and/or hauling in of a flexible elongate tensile member. The apparatus may be embodied, for example, in a device for controlling the descent of a person or an object from a height. It may also be utilised in an arrangement for paying out a rope or cable or tube from an aircraft in flight, the rope, cable or tube having attached to one end a towed device which is to be deployed outside the aircraft in the aft airstream. The apparatus also finds other uses, for example in towing devices behind a ship.

[0002] In the examples above where a cable is utilised to deploy a towed device or to support a descending body, it is vital that paying-out of a cable be carried out at a controlled rate; if the cable is paid out too quickly, cable 'whipping' and excessive acceleration at the end of travel could result. Similar considerations apply when the cable and its attached device are being hauled in or up. The aim of the invention is to provide apparatus which acts to control the paying out and/or hauling in of a cable or other flexible elongate tensile member.

[0003] According to the present invention, there is provided apparatus for controlling the paying out and/or hauling in of a flexible elongate tensile member, the apparatus comprising a component having a through-bore through which the elongate tensile member is adapted to extend with a clearance between the member and the wall of the bore, said apparatus being characterised by means whereby the said clearance is filled along at least a part of the length of said through-bore with a fluid such that, in use, a shear force is generated in said fluid during paying out and/or hauling in of the member to create a desired resistance to movement of the flexible elongate member through the bore.

[0004] Preferably, the bore is of substantially circular cross-section and at one or both of its end portions the bore may have a length of increased cross-section.

[0005] The component may be in the form of a block with the bore extending axially therethrough.

[0006] Preferably, said fluid is in the form of liquid, e.g. a silicone liquid, but the fluid may be in the form of a gas.

[0007] The fluid is preferably contained in a reservoir arranged adjacent the component, and the reservoir may be of such dimensions that it surrounds the component; the flexible elongate member may then extend through the reservoir, in use.

[0008] The apparatus may include a storage device for the flexible elongate member, and, for example, the storage device may be in the form of a fixed cylinder mounted in the reservoir, one end of the cylinder may be formed with a radially inwardly extending portion to which said component is affixed.

[0009] The apparatus may comprise a valve arrangement whereby said fluid is supplied to the flexible elongate member and/or to the said clearance.

[0010] The apparatus may incorporate a device attached to the end of the elongate member which device is to be deployed in use in an airstream, and the apparatus may be adapted for mounting in or on a vehicle, e.g. a ship or an aircraft.

[0011] Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein:

[0012] Figure 1 illustrates a section through an apparatus for controlling the paying-out of a cable.

[0013] Figure 2 illustrates a section through a modified form of the apparatus of Figure 1.

[0014] In Figure 1, reference numeral 10 represents a component in the form of a block which is to be fixedly attached at an appropriate position towards the rear of an aircraft from which a cable 11 is to be paid out and hauled in. The cable is paid out from and may be hauled in onto a storage device eg, a winding drum. The cable 11 has attached to its rear end a towed device (not shown).

[0015] The block 10, as shown, is of cylindrical form and has a bore 12 extending there through which is of substantially circular section.

[0016] The cable 11 extends through the bore 12, in use, with clearance 13 between the wall 15 of the bore and the outer surface of the cable 11 and in the case of the circular bore 12, as shown, the clearance 13 is of substantially annular form. The block 10 may be thought of as a nozzle which discharges the cable at a controlled rate.

[0017] It is arranged that the clearance 13 will, during the paying-out process, be filled along at least part of the length of through-bore 12 with a fluid 14 having a viscosity appropriate to control the paying out of the cable, whereby the paying out occurs at a controlled rate.

[0018] As the cable 11 moves through the bore 12 a shear force is generated in the fluid 14 and it is the value of this shear force which controls the rate of pay-out. The shear force is a function of the length of the bore, the clearance between the cable and the wall of the bore, and the viscosity of the fluid itself, and this shear force will determine the pay-out rate of the cable. Such pay-out rate will also be a function of the tension in the cable.

[0019] These parameters will be appropriately pre-determined depending on the precise conditions under which the apparatus is to operate and ideally there will be a degree of adjustability provided , eg, the length of the bore, and/or the clearance value may be alterable, and temperature control may be utilised to alter the viscosity of the fluid being used.

[0020] The presence of fluid in the clearance 13 may be achieved in a number of ways. In the simplest case a reservoir for the fluid surrounds the block 10 and sufficient fluid 14 is held therein to ensure that the requisite amount is always present in the clearance 13. The reservoir extends longitudinally of the cable 11 which itself passes through opposite walls of the reservoir. Obviously appropriate sealing means are provided where the cable passes through the walls of the reservoir.

[0021] In the embodiment of Figure 2, a reservoir 21 for the viscous fluid is provided and the storage device 22 onto which the cable 11 is wound is located within the reservoir 21. The reservoir 21, as shown, is of generally cylindrical form with an axial wall 23 and end walls 24, 25. End wall 24 i.e. the right hand end wall, as shown, has an aperture 26 there through for passage of cable 11.

[0022] The storage device 22 in this embodiment effectively constitutes a fixed spool of generally cylindrical form. At its end 27 the axial wall 28 of device 22 is fixed at or adjacent to end wall 24. At its other end 29 the axial wall 28 of the device 22 is formed with a radially inwardly extending portion 30 retro-curved, as shown, and to the radially inward part of which is attached the block 10.

[0023] The viscous fluid 14 for use in controlling the paying-out of cable 11 is initially contained in the volume represented by the annular gap 31 between the axial wall 28 of device 22 and the axial wall 23 of cylinder 21 and also in the volume 32 between the curved portion 30 of device and the end wall 25 of the cylinder. As shown, the volumes 31, 32 are totally filled with fluid 14 but this is not essential, as long as there is sufficient fluid to generate the required shear force. In use, the cable 11 extends through aperture 26, axially through storage device 22, through block 10 and around the curved portion 29 and is wound onto axial wall 28 of the storage device; effectively the cable 11 is immersed in the fluid before paying-out. During controlled paying-out fluid passes through the block 10 and collects in the interior of storage device 22.

[0024] It is to be noted that in certain circumstances the reservoir need not have two end walls. Thus in circumstances where the apparatus of Figure 2 is mounted vertically or tilted relative to the 'horizontal' end wall 24 may be dispensed with.

[0025] In other arrangements a valve arrangement is provided to ensure the requisite supply of fluid from, eg, a reservoir or a compressor, the particular form of supply means depending on the fluid being used.

[0026] It has been found especially suitable to utilise a liquid, and a silicone liquid with a selected viscosity has proved particularly effective; in the case of a high viscosity liquid, specifically, it will be appropriate to provide one or both ends of the bore 13 with portions of increased cross-sectional area to improve ease of entry and/or exit of the liquid into the bore. Thus as shown in Figure 1 the left hand end of the wall of the bore has an outwardly diverging portion 16, and in Figure 2 both ends of the bore are formed with outwardly diverging portions.

[0027] In tests, effective control of paying-out of a cable of 3mm diameter has been achieved with a silicone fluid, utilising a block 10 of approximately 5mm length and with a clearance of approximately 0.4mm between the cable and the wall of the bore.

[0028] It is to be noted that the apparatus may be embodied so as to operate repeatedly or on a one-shot, e.g emergency, basis.

Claims

1. Apparatus for controlling the paying out and/or hauling in of a flexible elongate tensile member (11), the apparatus comprising a component (10) having a through-bore (12) through which the elongate tensile member (11) is adapted to extend with a clearance (13) between the member (11) and the wall (15) of the bore (12), said apparatus being characterised by means whereby the said clearance (13) is filled along at least a part of the length of said through-bore (12) with a fluid (14) such that, in use, a shear force is generated in said fluid (14) during paying out and/or hauling in of the member (11) to create a desired resistance to movement of the flexible elongate member (11) through the bore (12).

2. Apparatus as claimed in Claim 1 wherein the bore (12) is of substantially circular cross-section.

3. Apparatus as claimed in Claim 1 or Claim 2 wherein at one or both of its end portions (16), the bore (12) has a length of increased cross-section.

4. Apparatus as claimed in any preceding claim wherein said component is in the form of a block (10) and said bore (12) extends axially therethrough.

5. Apparatus as claimed in any preceding claim wherein said fluid (14) is in the form of liquid.

6. Apparatus as claimed in Claim 5 wherein said liquid (14) is a silicone liquid.

7. Apparatus as claimed in any one of Claims 1-4 wherein said fluid (14) is in the form of a gas.

8. Apparatus as claimed in any preceding claim wherein said fluid is contained in a reservoir (21) arranged adjacent the component (10).

9. Apparatus as claimed in Claim 8 wherein said reservoir (21) is of such dimensions that it surrounds the component (10).

10. Apparatus as claimed in Claim 8 or Claim 9 wherein the flexible elongate member (11) extends through the reservoir (21), in use.

11. Apparatus as claimed in any preceding claim comprising a storage device (22) for the flexible elongate member (11).

12. Apparatus as claimed in Claim 11 as appendant to Claim 8 or Claim 9 wherein said storage device (22) is in the form of a fixed cylinder mounted in the reservoir.

13. Apparatus as claimed in Claim 12 wherein one end of the cylinder is formed with a radially inwardly extending portion (30) to which said component (10) is affixed.

14. Apparatus as claimed in any preceding claim further comprising a valve arrangement whereby said fluid (14) is supplied to the flexible elongate member (11) and/or to the said clearance (13).

15. Apparatus as claimed in any preceding claim and comprising a said flexible elongate tensile member (11) in the form of a length of cable.

16. Apparatus as claimed in Claim 15 comprising a device attached to the end of the cable (11) which device is to be deployed in use in an airstream.

17. Apparatus as claimed in any preceding claim being adapted for mounting in or on a vehicle.

18. Apparatus as claimed in any one of Claims 1-14, being adapted for mounting in or on a ship or an aircraft.

19. Apparatus as claimed in any one of Claims 1-13 being adapted to control the descent of a body attached to the flexible elongate member.

Drawing