US3181182A - Floats - Google Patents

Description

May 4,' 1965 .1. DELARUELLE ETAL 3,181,182

FLOATS Filed Oct. 11, 1965 Avn-wrom zz'c 22a FIG 2 United States Patent O jaa l n canins. (ci. a-s) The present invention isa continuation-impart of our oo-pending patent Application No. 99,212, tiled on March 29, 1961, entitled Floats, now iatent No. 3,114,926, December 24, 1963.

We have described in said earlier application a buoyancy ioat comprising a rigid envelope surrounding a tiexible envelope formed from an impermeable material, said envelopes defining two chambers, the first of which contains a buoyancy mass comprising an elastic fluid under a pressure equal to the hydrostatic pressure corresponding to a predetermined immersion depth and the second of which is in communication with the outside of the tioat to permit entry of the surrounding liquid into the second chamber when the iioat is immersed. l

An object of the present invention consists in providing iioats of the type described, which are easy to manufacture and assemble.

Another object of the present invention consists in providing floats of the type described which can function smoothly and without mishap inthe course of repeated immersions and emersions.

Another object of the present invention consists in providing floats of the type described wherein the flexible envelone is substantially protected from the danger of excessive stresses taking place through large pressure differences on opposite faces of said envelope.

Another object of the present invention consists in providing floats of the type described wherein a satisfactory and predictable deformation of said llexible' envelope is obtained.

Another object of the invention consists in providing iioats of the type described, wherein perforations, provided to put said second chamber in communication with the outside of the float, are positioned with a view to reducing the strains and stresses to which said ilexible envelope is subjected when operating the floats.

With these and other objects in View, the present invention concerns floats of the type described wherein the fexible envelope defines said rst Vchamber and the rigid 'envelope denes said second chamber, the rigid envelope being apertured to establish said communication with the outside of the iloat.

Other objects of the invention will appear in the course of the following description.

In order to make the'above stated objects, as well as other objects of the invention, more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of an example one embodiment thereof, by means of one tigure showing a part elevational part sectional vertical view of a float according to the invention and one figure showing a longitudinal cross-sectional view `of a simple valve which may be used in the iioat.

FIG. 1 of the drawings shows a tioat having a rigid steel envelope in the shape of a tubular wall 1 assembled by welding at its opposite ends to two dome-shaped closing walls respectively indicated by numerals 2 and 3.

End wall 2 contains a large circular aperture i surrounded by an annular flange 6, which is welded to end wall 2 by means of an annular angle-shaped section 5 forming a vertical brim element around aperture d. To

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ange 6 is adapted to be ixed by a number or" bolts a rigid plate on the internal face of which is xed Aa sleeve shaped element 9 which carries a closing element comprising a dome-shaped closing plate 1d adapted t0 be positioned within the circular aperture 4.

The general shape of plate 1t? corresponds tothe shape of that portion of the end wall 2 which has been taken away to form aperture d, so as to provide a smooth transition along the contact line between wall 2 and plate 1d. Plate 1t? comprises a central holedelimited by an opstanding edge 11. Plate 1d can eventually be manufactored out of the portion which has been cut away from end wall 2 in order to form aperture 4. Rigid plate S includes a conical hole 12 situated opposite edge 11, and is adapted to receive on its outeiface a shackle 13 for fastening'the float to a cable 14.

End wall 3 comprises a central hole, circular in shape, and crowned by a hollow thimble 16 fixed to end wall 3 by weld 17, to form a water-tight seal.

Aperture l makes it possible to introduce easily within the rigid envelope a bladder 2t? made of imp rmeable fabric and adapted to be inflated to the shape of said envelope. Bladder Ztl carries, at opposite ends projecting metal fittings 21, 22, fastened to its fabric.

Fitting 21 is adapted to fit within hole 12 in rigid plate 8, and comprises a threaded extension 23 through which it can be locked in position by means of screws and washers assembly 24.

Fitting 22, which ts within hollow thimble 16, comprises also a threaded extension 2S, and includes an axial bore extending from end to end of said tting, which bore is normally closed at its outer end by means of screw plug Z6; fitting 22 contains an internal valve (not shown) adapted to enable the bladder to be lled by gas under pressure, and to prevent such gas from escaping. Fitting 22 can 'be locked in position by means of screws 27. A capping piece 28 is screwed on to hollow thimble 16, by means of screw threads provided at the latters upper end.

The space within the rigid envelope communicates with the exterior through perforations 30 formed Within rigid plate d, and perforations 31-"32 arranged in two concentric rings within closing plate 1t), sleeve element 9 having also a number of holes 33. Perforations 31-32 are small, so as to avoid damaging or puncturing the bladder when the pressure within said bladder is greater than the external pressure.

At least one ring 35 is welded on a stieniug ring 35 fixed around the tubular wall 1, for handling the oat, or for fastening on to it one or several compensating floats. For assembling the float, it is expedient to place the rigid envelope upside down, with the bottom opening facing upwards. Bladder 29, deflated and already assembled to plate S, is then inserted within said open# ing, the top end, bearing fitting 22, being inserted rst, and coming to nest Within t-hirnble 16. Said fitting 22 is then lixed by means ot screws 27, and plate 8 isbolted down on flange e.

Air is then inserted through the valve provided within fitting 22, under a predetermined pressure corresponding, say, to 1290 ft. or water depth, after which plug 25 is screwed down, and capping piece 28 is fixed on to thimble 16, the permanently conned pressurized air applying Y bladder 2Q tightly against the rigid envelope 1-243. The

oat is then ready to be operated.

FIG. 2 shows a longitudinal cross-sectional View of simple valve which may be employed with fitting 22.

This valve comprises a frame 22e which comprises, for example, three thin brackets (two of which are visible) joined at the center to hold a Weak spring 22a. A valve cover 22h is supported by the spring 22a so as to normally close opening 22d. When it is desired to introduce gas under pressure into bladder 2t), the gas pressure forces 22b away from the opening 22d permitting gas to enter. When the pressure of the gas insiderthe bladder rises to a point where it is slightly less than the pressure under which gas is being introduced, spring 22a urges cover 22b into its closed position. The unit is now ready for use and cover 22b will prevent any escape of gas during the submersion of the oat. Y

Perforations 31-32 are made suthciently small yto avoid damaging the `bladder when inflated. The diameter `of these perforations is preferably not greater than twice the thickness of the bladder iiexible envelope, and the inner edges of said perforations are preferably charnfered or rounded oif, to avoid bringing the bladder in contact with sharp arrises.

Rectangular openings maybe used instead of circular perforations, the width of each rectangle, defining each such opening, being preferably not greater than the thickness of the tiexible envelope.

In operation, the float, which may be attached on the surface to a submarine pipe in the course of laying, becomes progressively immersed with said pipe, keeping its buoyancy all the while, down to said 1200 ft. depth. As the immersion progresses beyond that depth, the outside water pressure becomes greater than the air pressure within the bladder, and water, entering the rigid envelope through perforations 31-32, begins to find a path between said envelope and bladder 2t), and to reduce progressively the air volume withinthe bladder, according to Boyles Law. fore from a 1200 ft. depth downward, to become equal to zero at a given depth, and to assume negative values beyond said given depth.

Conversely, when raising the pipe, for inspection or for any other purposes, the float net upward force `increases progressively and yregains its original value at the same depth of v1200 ft., after which it remains constant until it reaches the surface.

The perforations allowing entry of water in the rigid envelope are preferably positioned as one singlegroup of closely spaced perforations, located at a selected einplacement on said envelope, to enable the bladder vto go through the same process of deformation in the course of successive immersions. Said selected` emplacement is preferably situated in the vicinity of the lower fitting, so that the bladder portion which will be subjected to reverse The net upward force on the float decreases therecurvatures in the course of deformation, is one that will normally have an extra thickness of material to provide a strong xing point for said tting.

The oat thus described is capable of developing a variable buoyancy, which varies in a predictable manner according to its depth of immersion. It is also capable of being immersed and emersed in succession as often as may be required, with the bladder alternatively'contracting and expanding while it remains rigidly fastened at fixed points at opposite ends of the float, any given point of the bladder being thereby subjected to the same stress variation in the course of repeated operations.

What we claim is:

l. A float having a buoyancy adapted to vary automatically in function of its depth of immersion, comprising a rigid envelope and a iiexible envelope formed from an impermeable material in the shape of a bladder situated within the rigid envelope, said envelopes defining two chambers, one of the chambers being defined by the bladder which contains and permanently confines a buoyancy mass comprising `an elastic uid under a pressure equal to the hydrostatic pressure corresponding to a predetermined immersion depth, and the second of the chambers being defined by the rigid envelope, said rigid envelope comprising openingsto allow the surrounding liquid to penetrate within said-second chamber when the float is immersed beyond said predetermined depth, said oat cornprising an aperture withinrsaid rigid envelope for inserting said flexible envelope, a closing element for closing said f aperture, fastening means for holding said closing element positioned within said closing piece.

3. A float according to claim 1 wherein said openings are circular perforations of a diameter not greater than twice the thickness of the ilexible envelope. Y

4. A float according to claim l wherein said openings are charnfered on the periphery of their edges of contact with said iiexible envelope.

5. A float according to claim 1 wherein said openings are rectangular in shape, the smaller side of each rectangle being not greater than the thickness of the exible envelope.

6. A float according to claim 1 wherein the edges of contact of said openings with said flexible envelope are rounded olf.

7. An automatically variable buoyancy float comprising:

a rigid envelope in the shape of a surface of revolution formed about a vertical axis, said rigid envelope containing an inflatable bladder made of an impermeable exible material, said bladder being adapted, when inflated, to assume through swelling the shape of the rigid envelope;

an aperture for inserting said bladder within said rigid envelope, and a closing piecefor closing said aperture after insertion of the bladder, said closing piece being adapted to form part of the rigid envelope when in the closing position and including means adapted to fix it in said closing position;

fastening means secured to said bladder for fastening the bladder to said rigid envelope at opposite ends of said vertical axis, at least one of said fastening means `protruding outwardly through the rigid envelope; Y

within one of said protruding fastening means, a duct leading from the exterior to the space confined within the bladder, and a valve disposed within said duct, for retaining a pressurized gas within said space;

a plurality of perforations for-med through the bottom portion of said rigid envelope in the vicinity of the lower end of said vertical axis, and regularly spaced around said axis, to permit entry of the surrounding liquid within the rigid envelope.

8. An automatically variable buoyacny oat according to claim 7 wherein the rigid envelope comprises a vertical tubular wall, closed at top and bottom respectively by two dome-shaped end walls.

9. An automatically variable buoyancy oat according to claim 7 wherein the rigid envelope comprises a vertical tubular wall, closed at top and bottom respectively by two dome-shaped end -walls and said aperture is formed by cutting away a central circular portion within said lower dome-shaped end wall, said closing piece having a shape corresponding to that of said` Ycentral portion and comprising said perforations.`

10. An automatically variable buoyancy tloatraccord.- ing to claim 7 wherein said aperture is surrounded by a brim element secured to the rigid envelope, and said closing piece is secured on its outer face to a circular sleeve coaxial with the float along a rim of said sleeve, said sleeve being secured at its opposite rim to a rigid plate adapted to be fastened to said brim element, said rigid plate and closing piece having respective central openings coaxial with the float, through which openings the lower of said fastening means is adapted to protrude on the outer face of the rigid plate and to be secured to said rigid plate, said rigid plate comprising through holes forming ademas formed within the rigid envelope at the top end of said vertical axis, and ts snugly Within a hollow thimble tightly sealed to the rigid envelope around said opening, said fastening means having a threaded extension adapted to protrude outwardly through the upper end of said th'unble for securing said fastening means within said thirnble.

6 References Cited by the Examiner UNlTED STATES PATENTS FERGUS S. MDDLETON, Primary Examiner.

Claims (1)

1. A FLOAT HAVING A BUOYANCY ADAPTED TO VARY AUTOMATICALLY IN FUNCTION OF ITS DEPTH OF IMMERSION, COMPRISING A RIGID ENVELOPE AND A FLEXIBLE ENVELOPE FORMED FROM AN IMPERMEABLE MATERIAL IN THE SHAPE OF A BLADDER SITUATED WITHIN THE RIGID ENVELOPE, SAID ENVELOPES DEFINING TWO CHAMBERS, ONE OF THE CHAMBERS BEING DEFINED BY THE BLADDER WHICH CONTAINS AND PERMANENTLY CONFINES A BUOYANCY MASS COMPRISING AN ELASTIC FLUID UNDER A PRESSURE EQUAL TO THE HYDROSTATIC PRESSURE CORRESPONDING TO A PREDETERMINED IMMERSION DEPTH, AND THE SECOND OF THE CHAMBERS BEING

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