GB2153312A

GB2153312A - Propelling vehicles on vertical surfaces

Info

Publication number: GB2153312A
Application number: GB08501331A
Authority: GB
Inventors: Kenneth Edward Duell; Jon Peck
Original assignee: UVITEK
Current assignee: UVITEK
Priority date: 1984-01-18
Filing date: 1985-01-18
Publication date: 1985-08-21
Also published as: GB8501331D0

Abstract

A vehicle for attachment to and movement on a surface especially a leg of an offshore oil platform, having selectively actuable and deactuable attachment means 10, 11, e.g. electromagnets, movable relative to each other, and guide means such as an arcuate rod 7 along which at least one of the electromagnets can move, the guide means being of a shape to correspond to the profile of the structure on which the vehicle is to move, thereby to ensure good contact between the vehicle and the structure. <IMAGE>

Description

SPECIFICATION A vehicle This invention relates to a vehicle for attachment to and movement on a surface, especially but not exclusively for use on offshore structures such as oil rigs and oil production platforms.

It is necessary periodically to inspect and clean offshore structures as they are exposed to corrosion by seawater and attack by marine life such as shellfish, reducing the strength and effectiveness of the structure. Several inspection and cleaning devices have previously been proposed, but none lends itself te use in the "splash zone" of an offshore structure nor allows effective and controllable travel around a non-planar structure.

According to the present invention there is provided a vehicle for attachment to and movement on a surface and having a base, first and second attachment means on the base, the first attachment means being movable relative to the second and each of the attachment means being selectively actuable to lock the vehicle fast on the surface and deactuable to release said lock, the first attachment means being actuable when the second is deactuated and vice versa, wherein the base has non-linear guide means along which the second attachment means is movable.

The attachment means may be for example electromagnets, suction devices or mechanical clamps.

The guide means preferably corresponds in profile to the profile of a surface on which the vehicle is intended to move. Thus when the vehicle is for use on a structure having a regularly-curved surface the guide means has a curvature corresponding to that of the surface, so that the attachment means are regularly disposed on the surface. Movement of the first attachment means relative to the second allows the former to maintain constant distance from the surface of the structure.

The guide member is preferably arcuate for use on cylindrical surfaces such as the legs of offshore oil platforms.

A series of bases for the vehicle, or of guide members for fitment to the base, can be provided for use on structures having different surface configurations.

The attachment means may be remotely operated, for example through an umbilical which may extend, when the vehicle is for use in or below the sea, from a platform, remotely-controlled vehicle or mother ship.

Depending on the form of attachment means selected, the vehicle can be used on a variety of surfaces, for example concrete, ferrous or non-ferrous. When the surface is ferrous the attachment means are preferably electromagnets. The vehicle may carry on its base work tool items such as artic.ulated arms, television camera, stills camera, cleaning de vices or inspection devices for use at the surface of the structure.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a plan view of the base of a vehicle of this invention; Fig. 2 is an end view of an alternative vehicle of the invention attached to an offshore oil structure; Fig. 3 is a perspective view of a further vehicle of this invention; Fig. 4 is a perspective view of a still further vehicle of the invention; Fig. 5 is a bottom plan view of a face of an attachment means for use in a vehicle of the invention; and Fig. 6 is a side sectional view of a part of the attachment means of Fig. 5.

In the following description, corresponding parts in each embodiment of the invention will be given the same reference numbers.

In the embodiment of the invention referred to in Fig. 1 the vehicle has a base in the form of a generally rectangular tubular frame 1 having a pair of runners 4 on which slidable sleeves 5 are mounted. The sleeves 5 carry a framework 6 comprising a pair of parallel arcuate runners 7 between which extend a pair of struts 8 which are slidable on the arcuate runners 7 through sleeves 9. The arc of the runners 7 is centred on the centre of curvature of the structure to which the vehicle is to be applied.

Although not shown in Fig. 1, the frame 1 carries eight electromagnets, four disposed one at each corner of the frame 1 and four mounted on the struts 8. The struts 8 and their electromagnets are slidable as a unit on the arcuate runners 7 laterally of the frame 1, and the assembly made up of the framework 6 and their electromagnets is slidable as a unit on the runners 4 longitudinally of the frame 1. The four central electromagnets are suspended from the struts 8 on rigid shafts.

the electromagnets being pivotally mounted on the end of the shafts. The four corner electromagnets are similarly mounted.

Referring now to Fig. 2, the arrangement is generally similar to that of Fig. 1, differing mainly in constructional features. The electromagnets 10 are pivotally mounted on shafts 1 7 depending from the frame 1 while the electromagnets 11 depend from the framework 6, the runners 7 in this embodiment extending across the entire width of the frame 1 and being slidable along frame members 2.

The central electromagnets 11 are movable as a unit towards and away from an offshore oil platform leg 1 2 by means of a hydraulic ram 1 3. Movement of the electromagnets 11 along and across the frame 1 on their central framework 6 is also achieved hydraulically.

The electromagnets 10, 11 are selectively energised and deenergised by supply and cutoff of electric current. Hydraulic fluid and electric current are provided by means of an umbilical from the platform or from a freeswimming remotely controlled vehicle or deployment unit.

In Figs. 3 and 4 the sleeves 5A have welded to them brackets 14 secured to hydraulic cylinders 1 5 whose rams 1 6 are secured to stub shafts extending from the runners 4. Actuation of the rams 1 6 therefore moves the sleeves 5 and the framework 6 along the runners 4.

Hydraulic cylinders 1 8 and rams 1 9 extend between the arcuate runners 7 and the sleeves 9 for actuation to move the struts 8 along the arcuate runners 7.

The vehicle of Fig. 3 carries cleaning apparatus in the form of a pair of electricallyoperated brushes 20 which extend from the vehicle through an articulated arm 21 whose joints 22 are hydraulically operable through lines 23. The arm 21 is secured to the frame 1 through a bracket 24.

The hydraulic fluid for the rams 1 6 and 1 9 and the joints 22 is provided from a hydraulic power pack 25 mounted on the frame 1.

In use, the vehicles of these embodiments of the invention clamp magnetically to the ferrous leg 1 2 of the platform by energising the electromagnets 10, 11. To allow the vehicles to move on the leg the electromagnets 11 are deenergised, retracted from the leg 1 2 by the ram 1 3 and moved along the runners 7 and/or runners 4 to a new position.

The electromagnets 11 are re-engaged on the leg 12 and reenergised, the electromagnets 10 are de-energised and retracted from the leg 1 2 by extending the ram 13, and the frame 1 is moved relative to the now-fixed electromagnets 11 until the electromagnets 10 have reached their new position. The electromagnets 10 then re-engage the leg 1 2 and are reenergised. Repetition of these operations allow the vehicles to move to any position on the leg 1 2.

The provision of the arcuate runner 7, corresponding in curvature to the leg 1 2 by being concentric therewith, allows all eight magnets to be used in engagement with the leg 12, as the electromagnets 10, 11 can be maintained in selective contact with the leg 12 even when the vehicle is moving around the periphery of the leg 1 2.

Referring to Figs. 5 and 6, each of the electromagnets 10, 11 has a body 26 recessed regularly around the periphery of its face 27 to create cylindrical recesses 28 in each of which is screwed a cylindrical liner 29. A compression spring 30 bears at one end against an end face 31 of the liner 29, the other end of the spring 30 bearing against an inner face 35 of a small sub-electromagnet 32 which is held captive in the recess 28 by having a shoulder 33 engaging with an inwardly-directed flange 34 on the liner 29.

In use, when the vehicle is applied to the leg of an offshore oil structure and moves across its surface and each electromagnet 1 0, 11 contacts the leg, the small subelectromagnets 32 are energised and thus attracted to the ferrous surface. This causes the sub-electromagnets 32 to compress their associated springs 30 to an extent whereby all of the sub-electromagnets 32 contact the surface of the leg. Thus, in side view, the sub-electromagnets 32 together adopt a profile which is complementary to the cylindrical surface of the leg, and a large surface area of contact is established between the electromagnets 1 0, 11 and the leg.

This arrangement allows excellent locking of the electromagnets 1 0, 11 to the leg, which is of great importance in areas where the vehicle may be subjected to forces tending to wrench it from the leg, as for example are experienced in the splash zone where maximum adhesion is required.

The vehicle of the invention can be used on square, round, flat, oval, concave, convex, regular or irregular surfaces, Modifications and improvements may be made without departing from the scope of the invention.

Claims

1. A vehicle for attachment to and movement on a surface and having a base, first and second attachment means on the base, the first attachment means being movable relative to the second and each of the attachment means being selectively actuable to lock the vehicle fast on the surface and deactuable to release said lock, the first attachment means being actuable when the second is deactuated and vice versa, wherein the base has non-linear guide means along which the second attachment means is movable.

2. A vehicle as claimed in Claim 1, wherein the guide means corresponds in profile to the profile of a surface on which the vehicle is to move.

3. A vehicle as claimed in Claim 1 or 2, wherein the guide means is arcuate.

4. A vehicle as claimed in any one of the preceding Claims, wherein the guide means comprises an elongate member mounted on and extending from the base.

5. A vehicle as claimed in Claim 4, wherein the guide means is in the form of a pair of spaced elongate members which span across the base, the second attachment means being mounted on a subframe which is slidably mounted on the elongate members.

6. A vehicle as claimed in any one of the preceding Claims, wherein the guide means is movable on the base.

7. A vehicle as claimed in any one of the preceding Claims, wherein the relative move ment of the attachment means is produced hydraulically.

8. A vehicle as claimed in any one of the preceding Claims, wherein the attachment means comprise electromagnets.

9. A vehicle as claimed in any one of Claims 1 to 7, wherein the attachment means comprise mechanical clamps.

10. A vehicle as claimed in Claim 8, wherein the face of each electromagnet for contacting the surface has a plurality of submagnets each of which is individually movable towards and away from the surface in use so that said face can adopt the profile of the surface.

11. A vehicle as claimed in Claim 10, wherein the submagnets are in the form of pistons mounted in recesses in said face of the electromagnet.

12. A vehicle as claimed in Claim 11, wherein the submagnets are spring-biassed outwardly of said face.

1 3. A vehicle as claimed in any one of Claims 1 to 7, wherein the face of each electromagnet for contacting the surface has a removable contoured shoe corresponding in profile to said surface.

14. A vehicle for attachment to and movement on a surface, substantially as hereinbefore described with reference to and as shown in Fig. 1 of the accompanying drawings.

1 5. A vehicle for attachment to and movement on a surface, substantially as herein be fore described with reference to and as shown in Fig. 2 of the accompanying drawings.

16. A vehicle for attachment to and movement on a surface, substantially as hereinbefore described with reference to and as shown in Fig. 3 of the accompanying drawings.

1 7. A vehicle for attachment to and movement on a surface, substantially as hereinbefore described with reference to and as shown in Fig. 4 of the accompanying drawings.

18. A vehicle for attachment to and movement on a surface, substantially as hereinbefore described with reference to and as shown in Fig. 1 or 2 or Fig. 3 or 4 in conjunction with Figs. 5 and 6 of the accompanying drawings.