GB2126534A

GB2126534A - Underwater buoyancy apparatus venting control

Info

Publication number: GB2126534A
Application number: GB08323852A
Authority: GB
Inventors: Brian Leonard Buckle; Neil Charles Heesom
Original assignee: BUOYCO
Current assignee: BUOYCO
Priority date: 1982-09-07
Filing date: 1983-09-06
Publication date: 1984-03-28
Also published as: GB2126534B; GB8323852D0

Abstract

For an underwater buoyancy apparatus there is provided a device for venting gas from an expansible gas chamber of the apparatus when the rate of ascent of the buoyancy apparatus exceeds a predetermined velocity. The device has means 24-47 for monitoring the rate of ascent and providing a control signal when the predetermined velocity is exceeded, and a valve 20 controlling the venting of gas from the chamber. The monitoring means has a velocity member 47 which, in the ascent attitude of the device, extends laterally of the direction of ascent and is supported for movement upwardly and downwardly, and is exposed at its upper face to the ambient fluid so that sufficiently rapid ascent causes it to be urged downwardly, against spring loading 44, to decrease pressure in a chamber 41, allowing a piston 38 to move under air pressure. This allows air flow to a chamber 9, producing venting valve movement. <IMAGE>

Description

SPECIFICATION Improvements in and relating to underwater buoyancyapparatus The present invention refates to underwater buoyancy apparatus of the kind having an expansible gas chamber for providing the required buoyancy, which apparatus is referred to hereinafter as "expansible buoyancy apparatus". The invention has particu lar, but not exclusive, applicationto diver's lifejackets, dry suits, and underwater lifting bags.

The buoyancy of expansible buoyancy apparatus is provided initially by admitting gas, usually air, to the gas chamberofthe apparatus. In a diver's lifejacket, the gas chamber usually is constituted by a closed flexible container which is inflated by the gas. The flexible nature ofthe container permits of expansion of the gas within the container. Lifting bags usually comprise an open-ended flexible bag into which the gas is admitted. In some cases, the whole bag can constitute the gas chamber in similar mannerto a lifejacket. However, in other cases the gas chamber can be constituted by the area occupied by a gas pocket defined between the bag andwatercontained in the bag.In the latter case, expansion of the gas chamber occurs as a result of expansion of the gas pocket to displace waterthrough the open end ofthe bag.

It is difficult to control the ascent of expansible buoyancy apparatus because the progressive decrease in water pressure upon ascent of the apparatus causes progressive expansion ofthe gas chamber and hence a progressive increase in buoyancy, which in turn causes accelerated ascent of the diver or article to which the buoyancy apparatus is attached. This is a particular problem in the case of lifting bags where acceleration ofthe bag and the article being lifted constitutes a significant risk to those operating the lifting bags.

A device for venting gas from an expansible gas chamber of an underwater buoyancy apparatus is described and claimed in our co-pending United Kingdom Patent Application No.8117124 dated 4th June1981.

It is the object of the present invention to provide further improvements in the device setforth broadly in said co-pending application.

According to the present invention a device, in or for an underwater buoyancy apparatus for venting gas from an expansible gas chamberthereof, having means for monitoring the rate of ascent of the buoyancy control apparatus and providing a control signal when the ascent velocity exceeds a predertermined speed, and valve means controlling the venting of gas from the gas chamber and responsive to said signal to vent gas from the chamberto reduce the bouyancy of the apparatus, is characterised in that the monitoring means has a velocity member which, in the ascent attitude of the device, extends laterally of the direction of ascent and is supported for movement upwardly and downwardly, said velocity member being exposed at its upper face to the ambient fluid whereby sufficiently rapid movement ofthe device in the ascent direction urges the velocity member downwardly against loading, for opening of the venting valve.

The velocity member may have a rigid actuating member extending from it and movable with itto act directly or indirectly on the venting valve, e.g. through electrical, hydraulic, pneumatic and/or mechanical control meansforthe venting valve.

The venting valve may be arranged for opening it otherwise than as a result of control by the monitoring means, and in a preferred arrangement, the venting valve has a seating and a coacting valve member urged against said seating by loading, said valve member, being movableagainstthe loading away from a normal closed position ofthevalve by opening means accessible at the exterior of the valve, e.g. a pull-cord connected to the valve member.

The device may include pneumatic means for opening said venting valve means, said pneumatic means being actuable by said velocity member as a result of downward movement of the velocity mem beragainst its loading. In a preferred arrangement, the venting valve is pneumatically operable and a control valve is arranged in a gas supply line to the venting valve so as normally to close the supply line, the control valve having an operating stem connected to the velocity member. The venting valve in a first form includes a chamber connected to said gas supply line, said chamber being bounded by a flexible diaphragm operable to open the venting valve upon increase of pressure in the chamber.In another form the venting valve includes a chamber connected to said gas supply line, said chamber being bounded by a piston movable in a cylinder, said piston being operable to open the venting valve upon increase of pressure in the chamber.

Conveniently, the control valve is a normally closed two-way poppet-typewhiskervalve in which the whisker (i.e. tiltable operating stem) is engaged by the actuating member. In afurtherarrangement,the control valve is mounted in a gas exhaust line from a pneumaticactuatorwhich acts on a gas supply valve in the gas supply line to the pneumatic venting valve so as to normally close the line. Conveniently, the supply valve is a three-way valve which normally vents the gas supply line downstream ofthe valve.

Upon opening ofthe control valve, the release of gas from the actuator allows or causes the actuator to open the supply valve to supply gas to the venting valve for operation thereof.

The following is a description, byway of example only and with reference to the accompanying draw ings, of two presently preferred embodiments of the invention. In the drawings:- Figure lisa diagrammatic cross-sectional view through a device in accordance with a first embodi- ment ofthe invention for fitting to a lifting bag; Figure 2 is a diagrammatic cross-sectional view through a device in accordance with a second embodiment of the invention forfitting to a lifting bag.

Referring to Figure 1 ofthe drawings, a venting device generally indicated at 1 comprises an outer body2 having a central passage3which is threaded to receive a hollow stem 4 of an inner body 5. Between the outer body 2 and the inner body Sthere is defined a gap 6 into which can be introduced the neck of a lifting bag orthe like (not shown). Onto the outer body 2 there is threaded a housing 7 having a transverse wall 8which bounds a lower chamber 9 and an upper chamber 10. In the lowerchamber9there is positioned a sealing plate 11 having an annular rib 12 on which rests a resiliently deformable diaphragm 13.

The upperface of the diaphragm 13 is exposed to any residual fluid pressure present in the chamber 9, and the under side ofthe diaphragm is subject to the ambientfluid pressure, through passages 14 between the sealing plate 11 and diaphragm 13, and holes 15 in the wall ofthe housing 7. In the chamber 9, below the diaphragm 13, there is disposed a seal cap 16 which is urged downwardly by a compression spring 17 so as normally to seat onto the top of the body 2. The seal cap has a wide central aperture 18 within which there is disposed with clearance a stem 19 secured to the diaphragm 13 and which carries at its lower end a valve member20 which in the restconditionseats onto a seating 21 on the seal cap 16 and prevents exit of fluid from the passage 22 communicating with the interior of the lifting bag.

The chamber 9 communicates, through a passage 23 with an air supply controlled by a valve.

The valve has a snap-on connector 24 to receive an air hose (not shown) from an air supply. From the connector 24, an air passage 25 leads through a filter 26 and a passage 27 to a piston chamber 28. The passages 25 and 27 are formed in a nut 29 threaded into a valve body 30, with an "O-ring" 31 between them. The piston chamber 28 formed in the body 30 contains a spacer washer 32 against which is seated an O-ring 33 abutted by one end of a spacer cage 34.

Theotherend ofthespacercage abuts an O-ring 35 seated against a spacerwasher36abutting a union 37 threaded into the body 30. Within the spacer cage 34 there is positioned a piston 38 having a first large air passage 39 leading to a second smaller air passage 40 which opens into a space 41 containing a spring 42 which thrusts the piston to the right in this drawing.

The space 41 opens into a slightly smaller passage 43 containing a spring 44 which thrusts a valve 45, on one end of a rigid actuator rod 46, into a closed position. At the other end of the rod 46, there is mounted a velocity disc plate 47.

When the whisker valve 45,46 is closed, i.e. when thevelocitymember47 is not deflected by rush of water against it, owt is not deflected to a predetermined extent, the air pressures on each end of the piston 38 are balanced, and the spring 42 thrusts the piston into a closed position (to the right in this drawing) in which the piston closes off the passage 23. If the whisker valve is opened, as a result of deflection ofthe velocity member47,there is lowering of pressure in the space 41, with the result thatthe unbalance of pressures on the piston causes itto move to the left, in this drawing, thereby uncovering the passage 23 and permitting flow of air down the passage 23, to deflectthe diaphragm 13 downwardly for actuation ofthevent- ing valve.As soon as deflection ofthe velocity member is terminated, as a result of reduction of buoyancy and thus of speed of rise in the water, the whisker valve closes again, and pressure at both ends ofthe piston become equalised, so that the spring 42 then returns the piston to the right and thereby closes off the passage 23.

The chamber 10 in which the velocity member 47 is positioned has an opening 48 through which the upper face ofthe velocity member 47 is exposed to the relative downward movement of water as the entire device rises underthe effect of buoyancy. When the rate of rise exceeds a predetermined limit, the velocity member 47 permits entry of airto chamber 9. This depressesthediaphragm 13 and causes valve member 20 to be lowered away from the seating 21,thereby providing an escape path for airfrom the lifting bag (notshown)throughthepassage22, pasttheseating 21, and outthrough the passages 15, into the ambient fluid.This escape of airfrom the lifting bag decreases the rate of ascent, and the force exerted on the velocity member47 is accordingly reduced, so that the valve 45 eventually closes and the diaphragm 13 is allowed to returnto its unconstrained condition and thereby liftthevalve member 20 into sealing engagementwith the seat 21.

To permit rapid "dumping" of airfrom the lifting bag, the seal cap 16 can be lifted, againstthe pressure ofthe spring 17, by pulling manually on a cord 30 which is attached by a knot at 31 to the seal cap, and passes outthrough a hole 32, and has a handle 33 for its operation. Lifting of the seal cap 16 causes the seating 21 to be moved away from the valve member 20, so that a path for outflow of air is again provided through the passage 22 and passages 15.

Referring now to Figure 2 ofthe drawings there is shown a second embodiment ofvalve having a valve body 49 which is divided into upper and lower compartments by a transverse wall 50. The lower compartment49a is bounded by a wall 50a having an internal threading 51, and with holes 52 to the exterior.

A sealing plate 53 is threaded externally at 54to enable it to be screwed into the lower compartment 49a until an O-ring seal 55 abuts against a spacer ring 56 in the valve body 49.

The transverse wall 50 has a central opening 57 with an annular wall 58. The sealing plate 53 has a central sleeve 59 which, when the sealing plate is screwed fully home, abuts against an O-ring 60 abutting the annularwall 58. When the sealing plate 53 is screwed fully home, passages 61 provide a communication between the underside of the sealing plate, through the holes 52, to atmosphere.

The sleeve 59 plus a portion of the body ofthe sealing plate 53 together bound a cylinder 62 receiving a piston 63 having a packing ring 64 and having its rod 65 passing through an O-ring seal 66. The lower end of the piston rod 65 is engaged with a seal cap 67 which is urged downwardly by a compression spring 68 such that a washer 69 is urged into sealing engagement with a rib 70 on an outer body 71 which is likewise threaded into the lower part ofthe lower compartment 49a. The outer body 71 has a central opening 72 which is threaded at 73 to receive a threaded hollow stem 74 of an inner body 76.A gap 77 is defined between the inner body 76 and the outer body 71, and the neck of a lilting bag orthe like (not shown) can be introduced into that gap and the inner body 76 tightened to provide a seal at that zone.

The valve constituted by items 69 and 70 is normally closed under the pressune of the spring 68. The upper compartment 49 bof the valve body 49 has a peripher al wall 78 which is inturned atits upper pa rtto bound an opening 79, and has other openings 80 in itsside portion. Across the opening 79 there is positioneda flexible flap 81 carrying centrally a velocityplate82 mounted at the end of an actuator rod 83 of a valve assembly here denoted generally by the reference numeral 84 but of the same oonstruttion asthe valve denoted by reference numerals 24 to 45 in Figure 1. An air flow passage 85. equivalent to the passage 23 in Figure 1, leads from the valve 84 to an air space 86 which exists above the sealing plate 53 when screwed fully home. A passage 87 leads from the air space 86 to the space 88 below the piston 63.

The operation is as follows: When the velocity of ascent is giaatenougb to cause the velocity plate 82 to move downwards and open the valve 84, air flows through the passages 85 and 87 to space 88 and causes the piston 83 to rise, thereby lifting the seal cap 67 off the rib 70 and providing an esscape path from the interior of the lifting bag (not shown) through inner body 76, outer body 71, valve 69-70, passages 61 and holes 52 to the exterior

Claims

1. Adevice, in or for an underwater buoyancy apparatus for venting gas from an expansible gas chamber thereof, having means for monitoring the rate of ascent of the buoyancy control apparatus and providing a control signal when the ascentvelocity exceeds a predetermined speed, and valve means controlling the venting of gas from the gas chamber and responsive to said signalto vent gas from the chamber to reduce buoyancy of the apparatus, characterised in that the monitoring means has a vvelocity member which, in the ascent attitude of the device, extends laterally of the direction of ascentand is supported for movement upwardly and downwardly.said velocity member being exposed at its upper face to the ambient fluid where by sufficiently rapid movement of the device in the ascent dinection urges the velocity member downwardly againstloading, for opening of the venting valve.

2. A device, as claimed in Claim 1, where in the velocity member has rigid actuating member extending from it and movvable with it to act directly or indirectly on the venting valve.

3. Adevice, as claimed in either of Claims land 2, where in the venting valve is arranged for opening it other wise than as a result of control by the monitoring means

4. A device, as claimed in Claim 3, where in the venting valve has a seating and a coacting valve member urged against said seating by loading, said valve member being movable against the loading away from a normal closed position of the valve by opening means accessible at the exterior of the valve

5. A device, as claimed in Claim 4, wherein said opening means is a pull-cord connected to the valve member.

6. A device, as claimed in any one of the preceding claims, including pneumatic means for opening said venting valve means, said pneumatic means being actuable by said velocity memberas a resu It of downward movement of the velocity memberagainst its loading

7 Adevice,asclairned in Claim 6, whereinthe venting valve is pneumatica I ly operable and a control valve is arranged in a gas supply line to the venting valve so as normal lyto closethesupply line, the control valve having an operating stem connected to the velocity member

8. A device, as claimed in Claim 7, wherein the venting valve includes a chamber con nectedto said gas supply line, said chamber being bounded by a flexible diaphragm operable to open the venting valve upon increase of pressure in the chamber

9. A device, as claimed in Claim 7, where in the venting valve includesachamber con nectedtosaid gassupply line, said chamber being bounded by a piston movableinainder,said piston being operable to open the venting valve upon increase of pressure in the chamber

10. A device, for venting gas from an expansible gas chamber, substantially as described herein with reference to Figure 1. or to Figure 2 of the accompanying drawings.