Underwater escape apparatus
United States Patent 3902327
An ascent retarding apparatus for attachment to a one-piece escape suit is used in underwater escape. The retarding apparatus is operated automatically, at a predetermined depth below the water surface, to exert retarding action on the final portion of upward escape travel thereby at least to minimise the risk of air embolism developing.
US Patent References:
Ship retarding system or device
Jackson - February 1960 - 2923267
CONTROLLABLE BALLAST FOR UNDERWATER DIVING EQUIPMENT
Pinto - February 1970 - 3495413
Ship retarding system or device
Jackson - February 1960 - 2923267
CONTROLLABLE BALLAST FOR UNDERWATER DIVING EQUIPMENT
Pinto - February 1970 - 3495413
Inventors:
Guillerm, Roger Gabriel (Toulon, FR)
Masurel, Gerard Honore (Toulon, FR)
Honore, Lucien Robert (Bandol, FR)
Masurel, Gerard Honore (Toulon, FR)
Honore, Lucien Robert (Bandol, FR)
Application Number:
05/474070
Publication Date:
09/02/1975
Filing Date:
05/28/1974
View Patent Images:
Export Citation:
Assignee:
Etat, Francais
Primary Class:
Other Classes:
114/311
International Classes:
B63G8/40; B63G8/00; B63C9/00
Field of Search:
61/69,70,69A,71 114/16E,209 128/142.4
Primary Examiner:
Shapiro, Jacob
Attorney, Agent or Firm:
Larson, Taylor And Hinds
Claims:
We claim
1. Apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
2. Apparatus according to claim 1, in which the retarder means is convertible automatically from said stored position to an operative position of maximum drag when said control means effects said movement of the retarder means.
3. Apparatus according to claim 1, in which said control means is coupled to the housing.
4. Apparatus according to claim 3, in which said housing is made of two separable portions, said portions being separable by the control means to expose the retarder means to the surrounding water.
5. Apparatus according to claim 1, in which the retarder means comprises a parachute, said parachute being arranged in the housing in a folded condition.
6. Apparatus according to claim 5, in which said control means is pressure-responsive and is arranged to effect said movement of the retarder means when the apparatus has risen to said predetermined depth only when the water pressure prevailing at the maximum immersion depth of the apparatus at said location exceeds a predetermined value.
7. Apparatus according to claim 1, in which the control means comprises a control piston movable in a first direction in response to increasing water pressure, and movable in a second, opposite direction in response to decrease in water pressure, and latch means for providing an operative interconnection between said piston and said elongate element in said second direction after the piston has been moved to engage said latch means in response to a water pressure greater than a predetermined value.
8. Apparatus according to claim 7, in which the control means includes resilient means arranged to oppose movement of said control piston in said one direction, and in which said latch means includes at least one latch finger mounted on a slidable element.
9. Apparatus according to claim 8, in which the latch means includes a ring slidably mounted on a portion of the slidable element, said latch finger being pivotally connected to said ring, and an abutment being provided on the slidable element which is engageable by said ring when the latter moves in said second direction with said control piston whereby further movement of the piston, in the said second direction, is accompanied by cojoint movement of the slidable element in said second direction.
10. Apparatus according to claim 9, in which the housing comprises two casing shells, said shells being separable to expose the retarder means to the water surrounding the apparatus when said slidable element moves a predetermined distance in said second direction.
1. Apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
2. Apparatus according to claim 1, in which the retarder means is convertible automatically from said stored position to an operative position of maximum drag when said control means effects said movement of the retarder means.
3. Apparatus according to claim 1, in which said control means is coupled to the housing.
4. Apparatus according to claim 3, in which said housing is made of two separable portions, said portions being separable by the control means to expose the retarder means to the surrounding water.
5. Apparatus according to claim 1, in which the retarder means comprises a parachute, said parachute being arranged in the housing in a folded condition.
6. Apparatus according to claim 5, in which said control means is pressure-responsive and is arranged to effect said movement of the retarder means when the apparatus has risen to said predetermined depth only when the water pressure prevailing at the maximum immersion depth of the apparatus at said location exceeds a predetermined value.
7. Apparatus according to claim 1, in which the control means comprises a control piston movable in a first direction in response to increasing water pressure, and movable in a second, opposite direction in response to decrease in water pressure, and latch means for providing an operative interconnection between said piston and said elongate element in said second direction after the piston has been moved to engage said latch means in response to a water pressure greater than a predetermined value.
8. Apparatus according to claim 7, in which the control means includes resilient means arranged to oppose movement of said control piston in said one direction, and in which said latch means includes at least one latch finger mounted on a slidable element.
9. Apparatus according to claim 8, in which the latch means includes a ring slidably mounted on a portion of the slidable element, said latch finger being pivotally connected to said ring, and an abutment being provided on the slidable element which is engageable by said ring when the latter moves in said second direction with said control piston whereby further movement of the piston, in the said second direction, is accompanied by cojoint movement of the slidable element in said second direction.
10. Apparatus according to claim 9, in which the housing comprises two casing shells, said shells being separable to expose the retarder means to the water surrounding the apparatus when said slidable element moves a predetermined distance in said second direction.
Description:
FIELD OF THE INVENTION
This invention relates to apparatus intended for use in conjunction with an underwater escape suit provided with buoyant means for imparting an upward thrust to the user to permit escape from an underwater location to the water surface.
The invention is particularly, but not exclusively, concerned with providing apparatus for use in individually rescuing the members of the crew of a submarine in distress, or divers located at a great depth in a water-tight chamber.
It is known that submarines are equipped with one or more individual rescue flooding chambers. In the event of the submarine being in distress and being located at a depth of less than 300 metres below the surface, the members of the crew can escape separately by using the flooding chamber. For this purpose, each crew member puts on a one-piece suit and a hood, enters the chamber separately, and closes the communication door between the chamber and the submarine.
Water is admitted into the bottom of the flooding chamber and rises quickly in the latter, confining in the upper part of the chamber a bubble in which is situated the head of the crew member and the hood filled with air. As soon as the pressure in the flooding chamber is in equilibrium with the external pressure, an upper closure panel of the flooding chamber is automatically opened and the crew member is forced upwardly. The force of ascent is of the order of 200 Newtons and a limited speed of ascent of the order of 3 metres per second is achieved.
These operations are carried out very quickly so as to minimise the quantity of nitrogen which is dissolved in the blood during the compression and the first part of the upward travel and thus to avoid air embolism. For example, the pressurising and the opening of the flooding chamber can take about 30 seconds and the ascent from 300 metres to 60 metres can take about 80 seconds. During the ascent, the crew member (submariner) is able to breath in the air bubble which is enclosed in the hood. If desired, the hood can be replaced by any other equipment, e.g. buoyant means, ensuring the exertion of a lifting thrust on the crew member.
It is possible by this method to rescue the crew of a submarine in distress at depths of less than 180 metres.
As the depth of immersion increases beyond 180 metres, the frequency of accidents occurring due to air embolism also increases and, beyond 300 metres, this method becomes inapplicable, the chances of success being practically zero.
The air embolism is produced when the submariner enters the last part of the upward travel, during which decompression tends to occur too quickly.
Therefore, there exists a requirement at least to minimise the risk of air embolism occurring when an underwater escape suit is employed in escape to the water surface from an underwater location at a depth between 180 metres and 300 metres.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in the housing; and control means operable, when the apparatus has risen from the underwater location to a predetermined depth below the water surface, to effect engagement of the retarder means with the water surrounding the apparatus thereby to retard further upward movement thereof.
According to a further aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in the housing; and depth-responsive control means coupled with the housing and arranged to effect engagement of the retarder means with water surrounding the apparatus, at a predetermined depth during upward movement of the apparatus, thereby to retard further upward movement of the apparatus.
According to another aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in said housing; and depth-responsive control means coupled with said housing and arranged at least to open the housing and to effect engagement of the retarder means with water surrounding the apparatus, when the apparatus rises to a pre-determined depth below the water surface, thereby to retard further upward movement of the apparatus, said control means comprising an elongate element moveable longitudinally as a function of decreasing water pressure and coupled with the casing to effect opening of the latter when the water pressure decreases to a value corresponding to said predetermined depth.
The invention is also concerned with an underwater escape suit provided with apparatus as defined above.
The invention also provides a method of underwater rescue employing a one-piece suit having retarding apparatus coupled therewith to retard the speed of ascent from an underwater location, over a final portion thereof, in order to minimise the risk of air embolism developing.
Thus, by employing an embodiment of retarding apparatus according to the invention in conjunction with an underwater escape suit, it is possible to achieve a rapid ascent from an underwater location, in about 80 seconds from 300 metres to 60 metres at a rate of 3 metres per second, and then a slower ascent occupying 80 seconds from 60 metres to the surface at a rate of 0.7 metres per second. The exertion of the retarding action over the final portion from 60 metres to the surface provides a sufficient time period to avoid too rapid gas extraction with resultant formation of nitrogen bubbles in the blood vessels.
The invention is applicable to many types of underwater rescue situations, and particularly in the rescue of the crew of a submarine in distress, or divers working under the sea in chambers at atmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a general view of a one-piece underwater escape suit provided with retarding apparatus according to the invention;
FIG. 2 is a side view, partly in section, showing more detail of the retarding apparatus attached to the one-piece suit in FIG. 1;
FIG. 3 is a view, similar to FIG. 2, illustrating parts of the apparatus occupying one possible position taken-up during use of the apparatus;
FIG. 4 is a view similar to FIGS. 2 and 3, showing opening-out of retarder means of the apparatus; and
FIG. 5 is a diagram of pressure against time illustrating the ascent characteristics which can be achieved by a submariner having a one-piece suit provided with retarding apparatus according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to FIG. 1 of the drawings, there is shown a general view of a one-piece underwater escape suit of the type which can be employed in the escape from a submarine in distress. The one piece suit is designated generally by reference numeral 110 and may be of the type suitable for escape from an underwater location at depths of up to 300 metres below the water surface. The suit 110 has a retarder apparatus 100 attached thereto, namely to the leg of the suit, and which has the purpose of retarding the speed of ascent of the user during the last portion of his ascent from an underwater location. The suit 110 is provided in the usual way with a hood or helmet 120 which serves to form an enclosure for a bubble of oxygen or air which can be breathed by the user during his ascent from the underwater location. In addition to providing a source of oxygen for the user during his ascent, the hood 120 also constitutes buoyant means serving to provide an upward lifting thrust on the user to provide upward movement of the user from the underwater location. However, other forms of buoyant means known in the art may be provided.
One piece suits of the type illustrated in FIG. 1 have proved satisfactory in service for escapes at depths of immersion of less than 180 metres. While the one-piece suit can be used in escapes from as deep as 300 metres, the risk of air embolism occurring increases significantly as the depth of immersion increases from 180 metres to 300 metres. In the present state of the art, the one piece suit is not practicable for employment in escape attempts at depths below 300 metres.
The risk of air embolism occurring increases at depths greater than 180 metres mainly due to the too rapid ascent of the escaper over the last portion of his ascent e.g. the last 60 metres. It is for this reason that the ascent retarder apparatus 100 has been developed which is illustrated in FIG. 1 as attached to the lower part of the one piece suit.
The retarder apparatus 100 will now be described in more detail with reference to FIGS. 2 to 4 of the drawings. The apparatus 100 comprises a first casing generally indicated by reference numeral 2 and which houses ascent retarder means in the form of a parachute 1. The casing 2 is formed by two perforated half-shells 2a and 2b which enclose the folded parachute 1 as shown in FIGS. 2 and 3. As described in more detail below, the two half-shells 2a and 2b can be relatively separated from each other and from the remainder of the apparatus in order to effect engagement of the parachute with the water surrounding the apparatus by exposing the parachute 1 to the surrounding water flowing past the apparatus as shown in FIG. 4. The apparatus also includes a second casing 4 which houses a pressure responsive arrangement which is capable, when the apparatus is located initially at a depth greater than a predetermined minimum value, of operating automatically at a predetermined, higher level to effect exposure of the parachute 1 to the surrounding water flow so as to retard further upward travel of the apparatus.
The casing 4 houses control means for controlling the operation of the retarder means. Thus, the casing 4 houses a longitudinally slidable rod element 3, to the lower end of which the parachute 1 is fixed. The casing 4 is closed at its upper end by a threaded cover 4a (FIG. 2), on which is attached a snap hook 16 which can be employed to secure the apparatus to the outside of the rescued one-piece suit, for example, to the leg of the latter as shown in FIG. 1.
At the end remote from the cover 4a, the casing 2 is attached to the casing 4, and is held in an assembled state thereat, by means of resilient clips 5a, 5b, 5c and 5d. The half-shells 2a and 2b of the casing 2 are also held assembled by means of a ring 6 which surrounds the two half-shells at a location just above the engagement of the resilient clips 5a to 5d with the casing.
At its bottom end, the sliding rod 3 carries a plate 7 which forms a part of a release means to effect disassembly of the casing shell 2a and 2b and disconnection of the casing 2 from the casing 4. The function of the plate 7 will be described in more detail below with reference to FIG. 4.
Arranged inside the casing 4 is a control piston 8 which surrounds the central rod 3 and is slidably mounted within a cylinder 12 formed integrally with casing 4, the piston 8 being sealed relative to the rod 3 and the cylinder 12 by seals 11a and 11b which may take the form of O-rings. The bottom of the casing 4 is provided with openings 9 through which water surrounding the apparatus can be admitted to act on the adjacent face of the piston 8. The inflow of water through openings 9 is shown by arrows 10 in FIG. 3 and, evidently, will tend to apply an upward force on the piston 8 to move upwardly relative to the cylinder 12. To provide opposition to the upward movement of the piston 8, an annular support 14 surrounds the piston 8 and engages an upper shoulder 15 thereof, and a compression spring 13 is provided which surrounds the support 14 and applies downwards biasing thereto by reacting between an upper end portion of the apparatus and a lower flange portion of the support 14. It will be appreciated that, the greater the depth of immersion of the apparatus, the greater will be the upward forces generated on the piston 8 in opposition to the restoring force provided by spring 13.
At its upper end, the central rod 3 carries a sliding ring 17, from which are suspended hook like attachment fingers 18 pivotted to lugs 20 integral with the ring 17 on pivot pins 19 and forming latch means capable of forming an operative interconnection between the piston 8 and the rod 3 as described below. The fingers 18 are provided with peripheral outer notches 21 in which are fitted resilient rings 22 which collectively bias the fingers 18 radially inwards towards the rod 3. For a purpose described in more detail below, the rod 3 is also provided with an abutment shoulder 23 against which the lugs 20 can engage in one mode of operation of the apparatus. Also, the piston 8 is provided with a reduced wall thickness upper extension having an outwardly turned flange portion 25 with which, in certain circumstances, the hook- like fingers 18 can engage.
The operation of the apparatus will now be described. The apparatus 100 is attached to the outside of the rescue suit preferably by a snap hook 16, at a lower part of the suit, e.g. as shown in FIG. 1. Assuming that the escape suit is to be employed in escape from a submarine, the user enters the individual flooding chamber of the submarine and, as the flooding chamber fills with water, the water enters the retarding apparatus through openings 9 as indicated by arrows 10 in FIG. 3. It will be evident that the pressure of the water admitted through openings 9 will reach a pressure substantially corresponding to the pressure of the water surrounding the submarine.
As the water enters through the openings 9, the piston 8 is urged upwardly in a first direction against the action of the spring 13 which is thereby compressed and, if the immersion depth exceeds a predetermined limit, the water pressure corresponding to the immersion depth will raise the piston 8 until the flange portion 25 of the piston 8 comes into contact with the tapered surfaces 24 of the hook-like fingers 18. Further upward movement of the piston 8 causes the fingers 18 to pivot outwardly about their pivot pins 19 and agianst the action of the resilient rings 22. Still further upward movement of the piston 8 will result in the flange 25 becoming firmly latched into engagement with the fingers 18 which will be held in engagement therewith by the resilient rings 22. Thus, the piston 8 and the sliding ring 17 become latched together since the fingers 18 are connected to the lugs 20 secured to the ring 17, whereas the flange 25 forms an integral part of the piston 8. Therefore, as described in more detail below, opposite movement of the piston 8 in a second direction will be accompanied by corresponding downward movement of the ring 17.
The piston 8 and the sliding ring 17 are shown latched together in FIG. 3 and this represents a condition in which the pressure of the surrounding water is of such extent in relation to the force of the spring 13 that the parts can come into latching engagement. Thus, the force of the spring 13 can be selected in order to determine the depth at or below which the piston 8 is to be capable of latching with the ring 17. In the present instance, the arrangement is such that the piston 8 will come into latching engagement when the maximum immersion pressure is equal to or greater than 18 bars, corresponding to a depth of 180 metres. However, if the escape should be made from an underwater location which is of a depth of less than 180 metres i.e., near to the water surface, then the piston 8 will not rise to a sufficent extent within cylinder 12 as to come into latching engagement with fingers 18.
However, assuming the situation is as represented in FIG. 3 (corresponding to escape from an underwater location at a depth equal to or greater than 180 metres below the water surface), the piston 8 is latched to the fingers 18 and consequently to the sliding ring 17. Following opening of the flooding chamber, the submariner ascends to the surface by virtue of the buoyant effect of the air bubble within the hood 120. Evidently, during the upward travel, the surrounding water pressure will decrease progressively and, as a result, the piston 8 and the sliding ring 17 will carry out downward sliding movement relative to the cylinder 12 and also, initially, relative to the central rod 3. This downward movement relative to the central rod 3 continues during the ascent of the submariner until such time as the lugs 20 come into engagement with the shoulder 23 provided on the rod 3. Following this engagement, further downward movement of the piston 8 and ring 17 is accompanied by downward movement of the rod 3. Thus, the lower end of the rod 3 moves downwardly relative to the lower end of the casing 4 and this continues with increasing ascent of the submariner so that, eventually, the plate 7 attached to the lower end of the rod 3 applies sufficient downward force to the upper faces of the casing half-shells 2a and 2b that such half-shells become released from the attachments clips 5a and 5d and the ring 6 as shown in FIG. 4. This then exposes the parachute 1 to the water flowing relatively past the apparatus which causes the parachute 1 to unfold and exert a retarding action on further upward movement of the apparatus and therefore to the submariner. If desired, the parachute 1 can incorporate a spring which facilitates the opening operation thereof. Conveniently, the parachute 1 may be of the type employed e.g. as a drogue to facilitate the opening of a larger parachute during controlled descent through the atmosphere.
While it is preferred that the retarder means takes the form of a parachute it will be evident that other forms of retarder means (controlled by control means of the apparatus) could be housed within a casing and arranged to be capable of exerting a retarding action during the final portion of upward escape of the submariner when a predetermined depth is reached.
It will be evident that the position of the shoulder 23 provided on the rod 3 will determine the depth below the surface at which the parachute is automatically opened. If desired, the shoulder 23 may be replaced by an adjustably positionable device such as a threaded ring. In such event, the depth at which the retarding action is first initiated can be controlled. Conveniently, the arrangement is such that the parachute begins to exert retarding action at about 60 metres below the water surface.
Referring now to FIG. 5 of the drawings, there is shown a diagram illustrating the variation in water pressure as a function of time following an escape from an immersion depth of 300 metres.
The time for pressurising and opening the flooding chamber is 30 seconds, and the ascent from 300 metres to 60 metres takes place at a uniform speed of 3 metres per second occupying a travel time of about 80 seconds.
At 60 metres, the parachute is automatically exposed to the water flowing relatively past the apparatus and opens under the action of the resistance of the water, and the upward speed then is retarded to about 0.7 metres per second which then gives a time of ascent over the final portion of the escape from 60 metres to the water surface lasting about 90 seconds. Thus, the total time required for the operation is about 200 seconds. By providing the retardation over the final portion of the ascent, the risk of air embolism occurring is avoided or at least substantially reduced.
This invention relates to apparatus intended for use in conjunction with an underwater escape suit provided with buoyant means for imparting an upward thrust to the user to permit escape from an underwater location to the water surface.
The invention is particularly, but not exclusively, concerned with providing apparatus for use in individually rescuing the members of the crew of a submarine in distress, or divers located at a great depth in a water-tight chamber.
It is known that submarines are equipped with one or more individual rescue flooding chambers. In the event of the submarine being in distress and being located at a depth of less than 300 metres below the surface, the members of the crew can escape separately by using the flooding chamber. For this purpose, each crew member puts on a one-piece suit and a hood, enters the chamber separately, and closes the communication door between the chamber and the submarine.
Water is admitted into the bottom of the flooding chamber and rises quickly in the latter, confining in the upper part of the chamber a bubble in which is situated the head of the crew member and the hood filled with air. As soon as the pressure in the flooding chamber is in equilibrium with the external pressure, an upper closure panel of the flooding chamber is automatically opened and the crew member is forced upwardly. The force of ascent is of the order of 200 Newtons and a limited speed of ascent of the order of 3 metres per second is achieved.
These operations are carried out very quickly so as to minimise the quantity of nitrogen which is dissolved in the blood during the compression and the first part of the upward travel and thus to avoid air embolism. For example, the pressurising and the opening of the flooding chamber can take about 30 seconds and the ascent from 300 metres to 60 metres can take about 80 seconds. During the ascent, the crew member (submariner) is able to breath in the air bubble which is enclosed in the hood. If desired, the hood can be replaced by any other equipment, e.g. buoyant means, ensuring the exertion of a lifting thrust on the crew member.
It is possible by this method to rescue the crew of a submarine in distress at depths of less than 180 metres.
As the depth of immersion increases beyond 180 metres, the frequency of accidents occurring due to air embolism also increases and, beyond 300 metres, this method becomes inapplicable, the chances of success being practically zero.
The air embolism is produced when the submariner enters the last part of the upward travel, during which decompression tends to occur too quickly.
Therefore, there exists a requirement at least to minimise the risk of air embolism occurring when an underwater escape suit is employed in escape to the water surface from an underwater location at a depth between 180 metres and 300 metres.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in the housing; and control means operable, when the apparatus has risen from the underwater location to a predetermined depth below the water surface, to effect engagement of the retarder means with the water surrounding the apparatus thereby to retard further upward movement thereof.
According to a further aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in the housing; and depth-responsive control means coupled with the housing and arranged to effect engagement of the retarder means with water surrounding the apparatus, at a predetermined depth during upward movement of the apparatus, thereby to retard further upward movement of the apparatus.
According to another aspect of the invention there is provided apparatus intended for use in conjunction with an underwater escape suit, which suit is provided with means for imparting an upward thrust to the suit to permit escape from an underwater location to the water surface, the apparatus comprising:
a housing;
ascent retarder means arranged in said housing; and depth-responsive control means coupled with said housing and arranged at least to open the housing and to effect engagement of the retarder means with water surrounding the apparatus, when the apparatus rises to a pre-determined depth below the water surface, thereby to retard further upward movement of the apparatus, said control means comprising an elongate element moveable longitudinally as a function of decreasing water pressure and coupled with the casing to effect opening of the latter when the water pressure decreases to a value corresponding to said predetermined depth.
The invention is also concerned with an underwater escape suit provided with apparatus as defined above.
The invention also provides a method of underwater rescue employing a one-piece suit having retarding apparatus coupled therewith to retard the speed of ascent from an underwater location, over a final portion thereof, in order to minimise the risk of air embolism developing.
Thus, by employing an embodiment of retarding apparatus according to the invention in conjunction with an underwater escape suit, it is possible to achieve a rapid ascent from an underwater location, in about 80 seconds from 300 metres to 60 metres at a rate of 3 metres per second, and then a slower ascent occupying 80 seconds from 60 metres to the surface at a rate of 0.7 metres per second. The exertion of the retarding action over the final portion from 60 metres to the surface provides a sufficient time period to avoid too rapid gas extraction with resultant formation of nitrogen bubbles in the blood vessels.
The invention is applicable to many types of underwater rescue situations, and particularly in the rescue of the crew of a submarine in distress, or divers working under the sea in chambers at atmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a general view of a one-piece underwater escape suit provided with retarding apparatus according to the invention;
FIG. 2 is a side view, partly in section, showing more detail of the retarding apparatus attached to the one-piece suit in FIG. 1;
FIG. 3 is a view, similar to FIG. 2, illustrating parts of the apparatus occupying one possible position taken-up during use of the apparatus;
FIG. 4 is a view similar to FIGS. 2 and 3, showing opening-out of retarder means of the apparatus; and
FIG. 5 is a diagram of pressure against time illustrating the ascent characteristics which can be achieved by a submariner having a one-piece suit provided with retarding apparatus according to the invention.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to FIG. 1 of the drawings, there is shown a general view of a one-piece underwater escape suit of the type which can be employed in the escape from a submarine in distress. The one piece suit is designated generally by reference numeral 110 and may be of the type suitable for escape from an underwater location at depths of up to 300 metres below the water surface. The suit 110 has a retarder apparatus 100 attached thereto, namely to the leg of the suit, and which has the purpose of retarding the speed of ascent of the user during the last portion of his ascent from an underwater location. The suit 110 is provided in the usual way with a hood or helmet 120 which serves to form an enclosure for a bubble of oxygen or air which can be breathed by the user during his ascent from the underwater location. In addition to providing a source of oxygen for the user during his ascent, the hood 120 also constitutes buoyant means serving to provide an upward lifting thrust on the user to provide upward movement of the user from the underwater location. However, other forms of buoyant means known in the art may be provided.
One piece suits of the type illustrated in FIG. 1 have proved satisfactory in service for escapes at depths of immersion of less than 180 metres. While the one-piece suit can be used in escapes from as deep as 300 metres, the risk of air embolism occurring increases significantly as the depth of immersion increases from 180 metres to 300 metres. In the present state of the art, the one piece suit is not practicable for employment in escape attempts at depths below 300 metres.
The risk of air embolism occurring increases at depths greater than 180 metres mainly due to the too rapid ascent of the escaper over the last portion of his ascent e.g. the last 60 metres. It is for this reason that the ascent retarder apparatus 100 has been developed which is illustrated in FIG. 1 as attached to the lower part of the one piece suit.
The retarder apparatus 100 will now be described in more detail with reference to FIGS. 2 to 4 of the drawings. The apparatus 100 comprises a first casing generally indicated by reference numeral 2 and which houses ascent retarder means in the form of a parachute 1. The casing 2 is formed by two perforated half-shells 2a and 2b which enclose the folded parachute 1 as shown in FIGS. 2 and 3. As described in more detail below, the two half-shells 2a and 2b can be relatively separated from each other and from the remainder of the apparatus in order to effect engagement of the parachute with the water surrounding the apparatus by exposing the parachute 1 to the surrounding water flowing past the apparatus as shown in FIG. 4. The apparatus also includes a second casing 4 which houses a pressure responsive arrangement which is capable, when the apparatus is located initially at a depth greater than a predetermined minimum value, of operating automatically at a predetermined, higher level to effect exposure of the parachute 1 to the surrounding water flow so as to retard further upward travel of the apparatus.
The casing 4 houses control means for controlling the operation of the retarder means. Thus, the casing 4 houses a longitudinally slidable rod element 3, to the lower end of which the parachute 1 is fixed. The casing 4 is closed at its upper end by a threaded cover 4a (FIG. 2), on which is attached a snap hook 16 which can be employed to secure the apparatus to the outside of the rescued one-piece suit, for example, to the leg of the latter as shown in FIG. 1.
At the end remote from the cover 4a, the casing 2 is attached to the casing 4, and is held in an assembled state thereat, by means of resilient clips 5a, 5b, 5c and 5d. The half-shells 2a and 2b of the casing 2 are also held assembled by means of a ring 6 which surrounds the two half-shells at a location just above the engagement of the resilient clips 5a to 5d with the casing.
At its bottom end, the sliding rod 3 carries a plate 7 which forms a part of a release means to effect disassembly of the casing shell 2a and 2b and disconnection of the casing 2 from the casing 4. The function of the plate 7 will be described in more detail below with reference to FIG. 4.
Arranged inside the casing 4 is a control piston 8 which surrounds the central rod 3 and is slidably mounted within a cylinder 12 formed integrally with casing 4, the piston 8 being sealed relative to the rod 3 and the cylinder 12 by seals 11a and 11b which may take the form of O-rings. The bottom of the casing 4 is provided with openings 9 through which water surrounding the apparatus can be admitted to act on the adjacent face of the piston 8. The inflow of water through openings 9 is shown by arrows 10 in FIG. 3 and, evidently, will tend to apply an upward force on the piston 8 to move upwardly relative to the cylinder 12. To provide opposition to the upward movement of the piston 8, an annular support 14 surrounds the piston 8 and engages an upper shoulder 15 thereof, and a compression spring 13 is provided which surrounds the support 14 and applies downwards biasing thereto by reacting between an upper end portion of the apparatus and a lower flange portion of the support 14. It will be appreciated that, the greater the depth of immersion of the apparatus, the greater will be the upward forces generated on the piston 8 in opposition to the restoring force provided by spring 13.
At its upper end, the central rod 3 carries a sliding ring 17, from which are suspended hook like attachment fingers 18 pivotted to lugs 20 integral with the ring 17 on pivot pins 19 and forming latch means capable of forming an operative interconnection between the piston 8 and the rod 3 as described below. The fingers 18 are provided with peripheral outer notches 21 in which are fitted resilient rings 22 which collectively bias the fingers 18 radially inwards towards the rod 3. For a purpose described in more detail below, the rod 3 is also provided with an abutment shoulder 23 against which the lugs 20 can engage in one mode of operation of the apparatus. Also, the piston 8 is provided with a reduced wall thickness upper extension having an outwardly turned flange portion 25 with which, in certain circumstances, the hook- like fingers 18 can engage.
The operation of the apparatus will now be described. The apparatus 100 is attached to the outside of the rescue suit preferably by a snap hook 16, at a lower part of the suit, e.g. as shown in FIG. 1. Assuming that the escape suit is to be employed in escape from a submarine, the user enters the individual flooding chamber of the submarine and, as the flooding chamber fills with water, the water enters the retarding apparatus through openings 9 as indicated by arrows 10 in FIG. 3. It will be evident that the pressure of the water admitted through openings 9 will reach a pressure substantially corresponding to the pressure of the water surrounding the submarine.
As the water enters through the openings 9, the piston 8 is urged upwardly in a first direction against the action of the spring 13 which is thereby compressed and, if the immersion depth exceeds a predetermined limit, the water pressure corresponding to the immersion depth will raise the piston 8 until the flange portion 25 of the piston 8 comes into contact with the tapered surfaces 24 of the hook-like fingers 18. Further upward movement of the piston 8 causes the fingers 18 to pivot outwardly about their pivot pins 19 and agianst the action of the resilient rings 22. Still further upward movement of the piston 8 will result in the flange 25 becoming firmly latched into engagement with the fingers 18 which will be held in engagement therewith by the resilient rings 22. Thus, the piston 8 and the sliding ring 17 become latched together since the fingers 18 are connected to the lugs 20 secured to the ring 17, whereas the flange 25 forms an integral part of the piston 8. Therefore, as described in more detail below, opposite movement of the piston 8 in a second direction will be accompanied by corresponding downward movement of the ring 17.
The piston 8 and the sliding ring 17 are shown latched together in FIG. 3 and this represents a condition in which the pressure of the surrounding water is of such extent in relation to the force of the spring 13 that the parts can come into latching engagement. Thus, the force of the spring 13 can be selected in order to determine the depth at or below which the piston 8 is to be capable of latching with the ring 17. In the present instance, the arrangement is such that the piston 8 will come into latching engagement when the maximum immersion pressure is equal to or greater than 18 bars, corresponding to a depth of 180 metres. However, if the escape should be made from an underwater location which is of a depth of less than 180 metres i.e., near to the water surface, then the piston 8 will not rise to a sufficent extent within cylinder 12 as to come into latching engagement with fingers 18.
However, assuming the situation is as represented in FIG. 3 (corresponding to escape from an underwater location at a depth equal to or greater than 180 metres below the water surface), the piston 8 is latched to the fingers 18 and consequently to the sliding ring 17. Following opening of the flooding chamber, the submariner ascends to the surface by virtue of the buoyant effect of the air bubble within the hood 120. Evidently, during the upward travel, the surrounding water pressure will decrease progressively and, as a result, the piston 8 and the sliding ring 17 will carry out downward sliding movement relative to the cylinder 12 and also, initially, relative to the central rod 3. This downward movement relative to the central rod 3 continues during the ascent of the submariner until such time as the lugs 20 come into engagement with the shoulder 23 provided on the rod 3. Following this engagement, further downward movement of the piston 8 and ring 17 is accompanied by downward movement of the rod 3. Thus, the lower end of the rod 3 moves downwardly relative to the lower end of the casing 4 and this continues with increasing ascent of the submariner so that, eventually, the plate 7 attached to the lower end of the rod 3 applies sufficient downward force to the upper faces of the casing half-shells 2a and 2b that such half-shells become released from the attachments clips 5a and 5d and the ring 6 as shown in FIG. 4. This then exposes the parachute 1 to the water flowing relatively past the apparatus which causes the parachute 1 to unfold and exert a retarding action on further upward movement of the apparatus and therefore to the submariner. If desired, the parachute 1 can incorporate a spring which facilitates the opening operation thereof. Conveniently, the parachute 1 may be of the type employed e.g. as a drogue to facilitate the opening of a larger parachute during controlled descent through the atmosphere.
While it is preferred that the retarder means takes the form of a parachute it will be evident that other forms of retarder means (controlled by control means of the apparatus) could be housed within a casing and arranged to be capable of exerting a retarding action during the final portion of upward escape of the submariner when a predetermined depth is reached.
It will be evident that the position of the shoulder 23 provided on the rod 3 will determine the depth below the surface at which the parachute is automatically opened. If desired, the shoulder 23 may be replaced by an adjustably positionable device such as a threaded ring. In such event, the depth at which the retarding action is first initiated can be controlled. Conveniently, the arrangement is such that the parachute begins to exert retarding action at about 60 metres below the water surface.
Referring now to FIG. 5 of the drawings, there is shown a diagram illustrating the variation in water pressure as a function of time following an escape from an immersion depth of 300 metres.
The time for pressurising and opening the flooding chamber is 30 seconds, and the ascent from 300 metres to 60 metres takes place at a uniform speed of 3 metres per second occupying a travel time of about 80 seconds.
At 60 metres, the parachute is automatically exposed to the water flowing relatively past the apparatus and opens under the action of the resistance of the water, and the upward speed then is retarded to about 0.7 metres per second which then gives a time of ascent over the final portion of the escape from 60 metres to the water surface lasting about 90 seconds. Thus, the total time required for the operation is about 200 seconds. By providing the retardation over the final portion of the ascent, the risk of air embolism occurring is avoided or at least substantially reduced.