US2915059A - Autonomous closed-cycle diving apparatus - Google Patents

Description

Dec. 1, 1959 Y. LE MASSON AUTONDMOUS CLOSED-CYCLE DIVING APPARATUS Filed July 18, 1956 2 Sheets-Sheet 1 FIG] Dec. 1, 1959 Y. LE MASSON 2,915,059

AUTONOMOUS CLOSED-CYCLE DIVING APPARATUS Filed July 18, 1956 2 Sheets-Sheet 2 ""L, AVA-:71

United States AUTONOMOUS CLOSED-CYCLE DIVING APPARATUS Yves Le Masson, Paris, France, assignor of one-third to Michel Piel, Beauvallon, and one-third to Henri Heaulme, Blois, France a i I This invention relates to diving apparatus. The objects of the invention include providing an improved diving apparatus or suit of the autonomous type operating on a closed-cycle principle. More particularly, the device should be lightweight, usable at comparatively great diving depths and for long diving periods, and should provide the diver with the possibility of normal breathing regardless of the depth at which he is positioned and without requiring him to effect manual adjustments during the dive.

A feature of the invention is that the artificial breathing mixture or atmosphere in the closed cycle is contained in a false lungs device, i.e. a variable storage tank defined by a moving or collapsible wall. This device is supplied through a valve andnozzle from a source of atent fflce oxygen under pressure at a substantially constant rate of delivery while the volume of the breathing mixture is maintained at an approximately constant value by automatically supplying thereto suitable amounts of inert or neutral gas and automatically discharging therefrom suitable amounts of excess atmosphere as may be required under varying pressure conditions.

The inert gas may be nitrogen as in atmospheric air if the apparatus is used at relatively small diving depths, but advantageously a lighter inert gas such as helium may be used for greater depths.

Owing to the closed-cycle character of the apparatus, it adapted to insure respiration over long diving periods and, moreover, it can operate without the discharge of gas bubbles, which indicate the position of the diver, when the diving depth does not decrease.

The apparatus is free of the deficiencies of diving apparatus employing pure oxygen which are useless beyond diving depths of the order of about ten meters.

The fact that the volume of the atmosphere contained in the false lung device is automatically held constant and that the pure oxygen is delivered at a constant rate, will insure a satisfactory automatic supply of the respiratory mixture without requiring any adjustments to be made during a dive.

-To provide a clearer understanding of the principles on which the invention is based, some of the physiological aspects involved in the respiratory process in a pressure medium will first be summarized.

At normal atmospheric pressure, the average rate of consumption of the average individual during periods of normal activity is about 500 cubic centimeters of oxygen per minute, corresponding to a gravimetric rate of about one centigram per second.

As the pressure of the medium increases, oxygenation reactions also increase in rate and it is found that for pressures of about two atmospheres absolute, the human body is capable of absorbing ten times more oxygen per second than at atmospheric pressure, i.e. ten times more than the body requires. This value of concentration 10 is lethal to human beings and should under no circumstances be attained. Permissible upper limits of concentration should be selected within the range of from 1 to about 9.

, 2,915,059 Patented Dec. 1, 1959 For a given mass of blood in the body, there corresponds a predetermined oxygen concentration necessary for maintaining life. It follows from the foregoing that this oxygen consumption rate is of the order of 1 cg. per secondand corresponds to what will hereinafter be termed concentration 1. This is a constant independent of ambient pressure.

The problem therefore is to control, with an increasing pressure of the medium, the mass of oxygen consumed per'second in-such a way that it will be at least equal to the required quantity (concentration 1) while remaining less than the lethal limit (concentration 9 or 10).

The principle on which the autonomous closed-cycle diving apparatus. of the invention is based, resides in the recognition of the above disclosed physiological phenomena and laws, and in the provision of an automatic oxygen-regulating mechanism operative to satisfy, at all times, the requirements set thereby.

In addition to the above considerations, it should be noted that, underwater, the average respiratory rhythm is about one inhalation every two. seconds, which corresponds to an oxygen consumption'per inhalation, taking concentration 1 as a basis, equal to 2 centigrams, or a volume of 0.014 liter at atmospheric pressure. Since the average lung capacity is 2 liters, it is seen that owing to the small volume of oxygen that is required, it becomes necessary to supply a certain supplemental amount of inert gas.

The choice of this neutral gas depends on the pressure at which the diver is exhaling. In the case of atmospheric air, the major part of the neutral gas is nitrogen. Nitrogen has a density of 0.9 at atmospheric pressure, and its density increases with pressure, so that when the pressure reaches, for example, the value of 6 atmospheres which is the pressure prevailing at about a 60 meters depth underwater, the corresponding density is 5.4. Experience shows that this density is conducive to a type of physiological intoxication known as depth sickness which is sometimes fatal.

For diving depths of from 0 to 60 meters therefore, nitrogen may be used as the neutral make-up gas. For greater depths however a neutral gas should be selected having a lower density such as helium or hydrogen; in this way the theoretical limit can be extended to as much as 600 meters in depth.

The diving apparatus of the invention takes into account also this last-mentioned physiological efiect.

In satisfying the various requirements set forth above, the diving apparatus of'the invention may comprise four sections or units:

(1) Means for ensuring a substantially constant rate of oxygen delivery in order to maintain an acceptable concentration value.

(2) Means for maintaining av constant volume of respirable mixture (about 2 to 3 liters in value) at all times free of carbon dioxide gas.

(3) Means for automatically supplying neutral makeup gas to maintain the respirable volume constant as the depth and pressure increases.

(4) An overflow'relief valve for discharging any excess of gas from the respirable volume as the pressure decreases. I

The system including the above units constitutes, together with the lungs of the diver, a closed cycle system.

With the apparatus placed under atmospheric pressure the device for providing a constant rate of oxygen deper second, the actual quantity that is required in practice at any given time varies with the muscular exertion, respiratory capacity, and like factors, so that a lack or an excess of oxygen might result. A lack of oxygen is not permissible. An excess of oxygen on the other hand will result in a regular increase in the respirable volume which, as stated above, it is desired to retain constant. Consequently, there is no satisfactory operation of the system out of Water, since the unconsumed oxygen in excess will then escape through the overflow valve. in this sense, the system will not then operate in a closed cycle.

Now assuming that the apparatus thus adjusted is lowered to a depth of say 10 meters, the pressure increases to two atmospheres and the above-mentioned volume (two liters at 1 atmosphere) is reduced by half and makeup gas is automatically added to it by the means (3) to maintain the volume the same. The respirable volume therefore still remains the same, i.e. equal to the capacity of the users lungs. But since on the other hand the oxygen absorption capacity of the user has been increased tenfold (concentration 10) the excess of oxygen which occurred at surface conditions, is now taken up. The system operates in a fully closed cycle, so long as the oxygen concentration does not exceed the users absorption capacity.

The upper limit of concentration at moderate depths is determined by the depth. Beyond 9 meters depth the concentration may be chosen freely, provided it be selected within the range of from 1 to 10. I

With the apparatus operating at constant depth, only the means 1) and (2) are operative. When the apparatus is lowered to greater depths, the means (I), (2) and (3) operate. When the apparatus is raised, the volume increases and the means (1), (2) and (4) become operative.

The means (1) for insuring constant rate of oxygen delivery may comprise a simple expansion valve followed by a calibrated orifice or nozzle. However such an assembly will not maintain a strictly constant rate of oxygen delivery, since the rate will vary as the square root of the absolute pressure.

In order to compensate for the increase in delivery rate with pressure, an expansion spring biassing means, such as an adjustable stop, may be placed under the control of an absolute pressure-responsive member, e.g. an aneroid element, so that the spring bias will be reduced as the absolute pressure is increased. The pressure differential across the expansion orifice will then decrease as the absolute pressureincreases and, since the rate of flow is proportional both to the square root of the absolute pressure and to the square root of the differential pressure, the rate of oxygen delivery may be held constant or may be made to rise very slightly with pressure.

As regards the third means, i.e. the means for supplying make-up gas, these may be made to operate under control of the movements of the false lung device. The control may be mechanical with the false lung actuating through a lever or other linkage, a valve biassed to its closed position so as to open said valve as the false lung collapses. With such a mechanical arrangement however the user will have to exert increasing muscular force to inhale as the driving depth increases in order to open the valve.

Accordingly, in a preferred embodiment of the invention which overcomes this difliculty, the valve is operated by the pressure within a chamber into which the oxygen intake conduit connects and communicating with the false lung through a conduit which becomes sealed by the false lung when the latter has collapsed a suflicient predetermined amount.

As the pressure rises, the false lung seals the conduit at the end of the inhalation phase. Hence the pressure in the chamber, into which oxygen continues to be delivered, rises, thereby opening the valve and supplying an additional amount of the gas without any effort on the part of the divers lung muscles.

Two alternative embodiments of diving apparatus according to this invention will now be described for purpose of illustration but not of limitation with reference to the accompanying diagrammatic drawings wherein:

Fig. 1 is a sectional view of one embodiment of the invention; and Fig. 2 is a similar view of a modification.

As shown in Fig. 1, the diving apparatus comprises a central body 1, having secured to or integrally formed with it a pair of expansion units or valves 2 and 3 supplied with pure oxygen and neutral gas respectively from the storage containers 4 and 5. Each expansion valve may be of a conventional kind including a diaphragm acting on a valve, one side of the diaphragm being actuated by the gas pressure on the downstream or delivery side while the other side of the diaphragm receives the combined action of the pressure of the ambient medium and of an adjustable biassing spring.

The body 1, into which the expanded oxygen and neutral gas are delivered from the units 2 and 3, is connected with a reservoir 6 containing a substance adapted to absorb carbon dioxide gas, such as soda lime or another suitable absorber of C0 The body 1 is further connected with the interior space of a false lung device or collapsible container 7. This may comprise a bag or tank defined by a fluid-tight, flexible wall having a circular orifice 8 sealed betweenthe body 1 and a protective hood 9 of generally cylindrical shape having one end screwed into the body 1. The outer end of the hood may be hemispherical and is perforate so as to allow the surrounding medium, water, to contact the outer face of the bag 7 of the false lung during a dive.

The false lung 7 is adapted to move from the expanded full-line position to the retracted or collapsed position shown in chain lines, and in so doing the capacity of the lung changes by about 3 liters.

Connected with the reservoir 6 are two corrugated flexible tubes 10 and 11 leading to a T-connector 12 (see Fig. 2). The tube 10 is for inhaling and tube 11 for exhaling, and each tube is fitted with a one- way checkvalve 13 and 14 respectively, whereby the gas is allowed to flow only in the directions indicated by the respective arrows. V

The excess pressure within the outlet chamber 15 of the oxygen expansion valve 2 with respect to the externai pressure may be read on the dial of a pressure gauge connected with the coupling 16 and is adjustable by means of a knob 17 to a constant value regardless of the depth, so that the rate of oxygen delivery into the chamber 15 in body 1 through the calibrated orifice or nozzle 18 will be substantially constant.

The neutral-gas expansion valve 3. delivers into the body 1 through a valve 19 biassed to its sealing position by a spring 19a and operated in opposition thereto by a trigger lever 20 adapted to be actuated by the bag 7 when in its inturned or collapsed position, after the divers breathing has sufliciently emptied the false lung of its contents and has used up the full extent of variation of the capacity thereof.

The body 1 or reservoir. 6 is connected with the exterior through an outlet valve 21 biassed by a spring so as to open when the internal pressure exceeds the external pressure by a small predetermined differential amount.

The system operates as follows: During a dive and beyond a predetermined depth, the rate of oxygen delivery, as adjusted for a concentration selected within the range of from 1 to 10 as previously explained, is entirely absorbed by the users lungs, while the neutral gas exhaled by the diver flows through the reservoir 6 for absorption of the carbon dioxide thereof. If the diving depth remains constant, the breathing gas recycled over the circuit retains a constant volume and, at each inhaling, the bag 7 retains a position in which it is not sutficiently collapsed to actuate the trigger 20. Thus, the valve 3 remains inoperative to supply make-up gas. If the depth and pressure increase, the volume of respirable mixture decreases, and as the diver fills his lungs with the mixture, the false lung 7 collapses sufliciently to open the valve 19 and feed in an additional amount of neutral gas which will again maintain the volume of gas at a value corresponding to the capacity of the divers lungs. If, on the other hand, the depth and external pressure decrease, the internal gas increases in volume but, since the maximum volume offered to it as determined by the fully expanded condition of the bag 7 is limited there is an excess of internal pressure over the pressure of the external medium, and the excess of mixture escapes through the valve 21.

All of the above operation is of course fully automatic throughout the diving process Which may be continued until exhaustion of the oxygen store or that of the ab sorbing capacity of the reservoir.

The embodiment shown in Fig. 2 also comprises a body 1 the interior of which communicates with the false lung 7 and also with the reservoir 6 containing carbon dioxide absorptive material.

Just as in the first embodiment, the reservoir 6 is connected by the conduits 22 and 23 via chamber C with the flexible tubes 10 and 11 serving respectively for the outlet and inlet of the breathing mixture, and each of which is fitted with a check valve 13 or 14. Extending through the reservoir 6 is a conduit 24 connected at its ends with the interior of body 1 and with a chamber 25 respectively.

The oxygen tank 4 is connected to the chamber 25 by way of a manually-operable needle-valve 26, a conduit 27, a valve generally designated 2, and a jet orifice 18. The valve 2 comprises gas-pressure operated system including a valve 28 controlled by a diaphragm 29.

One side of the diaphragm 29 is subjected to the combined action of the downstream gas pressure and a bias spring 30 which tend to urge the valve to its sealing position, While the other side of the diaphragm receives the action of the external pressure and an adjustable spring 31 urging the valveto open position. The spring 31 engages a stop 32 engaged by one end of a lever 33. The other end of the lever is actuated by a barometric capsule or bellows 34 partially filled with liquid under pressure.

The chamber 25 may moreover be placed in communication with the tank of neutral gas by way of a handoperated needle-valve 35, a conduit 36 and a check-valve which may be considered as an expansion valve mounted in inverted relation, and generally designated 37. The valve includes a check-valve member 38 connected with a diaphragm 39. One side of this diaphragm is acted upon by the pressure in chamber 25 acting to open the valve, while the other side of the diaphragm receives the combined action of the external pressure and a biassing spring 40 acting to close the valve.

When the diver is positioned at a given depth, oxygen flows at a constant rate into chamber 25 and, through conduit 24, into the body 1. Should the diving depth increase, the oxygen fiow rate would tend to increase. However, the increase in external pressure due to the increase in depth will cause a collapse of the capsule 34 and hence a reduction in the compression stress of biassing spring 31. This reduction in the compression of the spring offsets the effect of the increase in external pressure on the expansion valve, so that the delivery rate of oxygen can be maintained at a strictly constant value regardless of the external pressure by suitably dimensioning the barometriccapsule 34.

The valve 38 is normally maintained seated by spring 40 so that the delivery of neutral gas is cut off. As the outer pressure increases, the volume of gas within the false lung increases and, at a predetermined point in the operation, the wall of the lung engages the end of the conduit 24 towards the end of an inhaling action, so that the conduit is sealed ofi. Since oxygen continues to flow into chamber 25, the pressure in the chamber rises, unseating valve 38 and thus resulting in a supply of makeup neutral gas into the respiratory circuit. It will be observed that, in contrast to what occurs in the embodiment of Fig. 1 the diver does not have to expend any additional muscular effort to open the valve, since the valve opening is produced pneumatically by the pressure obtaining in chamber 25.

What I claim is:

1. In a diving device, a collapsible container having a flexible wall, means for connecting in a closed circuit said container with the respiratory organs of the user of said apparatus, means for delivering oxygen into said container at a substantially constant rate, and means for maintaining the volume of respirable mixture in said closed circuit substantially constant.

2. In a diving device, a collapsible container having a flexible Wall, means for connecting said container with the respiratory organs of a diver in a closed circuit, means for delivering oxygen into said container at a substantially constant rate, means responsive to surrounding pressure and to said collapsible container for supplying neutral-gas into said container when said pressure increases and means coupled to said container for discharging excess respirable mixture from said container when said pressure decreases.

3. In a diving device, a collapsible container having a flexible wall, inhaling and exhaling conduits for com necting said container with the respiratory organs of a diver in a closed circuit, a tank of oxygen gas coupled to said container, a tank of neutral-gas, means connecting said neutral-gas tank with said container including a valve biassed to closing condition, actuating means connected with the valve and responsive to said collapsible container to open the valve and deliver neutral gas into said container, and relief valve means connecting said container with the exterior, whereby said closed circuit will contain at all times a substantially constant volume of respirable mixture.

4. The combination claimed in claim 3 comprising an expansion valve connected with said oxygen tank and a jet orifice connected with the expansion valve to deliver expanded oxygen at a substantially constant rate into said container.

5. The combination claimed in claim 4 comprising manual adjusting means for variably biassing said expansion valve.

6. The combination claimed in claim 5, wherein said actuating means comprises a mechanical linkage.

7. The combination claimed in claim 5, wherein said actuating means comprises a gas-pressure operated system.

8. The combination claimed in claim 5, wherein said actuating means comprises a chamber coupled to the first said means, a fluid passage between said chamber and said container and positioned to be engaged by said flexible Wall to be sealed thereby, and means responsive to the pressure in said chamber for operating said expansion valve.

9. The combination claimed in claim 4 comprising adjustable spring bias means for the expansion valve, and an element responsive to external pressure and operative to adjust said bias means in accordance with said external pressure.

10. The combination claimed in claim 4, wherein said neutral-gas is selected from the group consisting of hydrogen and helium.

References Cited in the file of this patent UNITED STATES PATENTS 1,681,029 Cooke Aug. 14, 1928 FOREIGN PATENTS 680,053 Germany Aug. 21, 1939 542,955 Great Britain Feb. 4, 1942

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