US3021839A

US3021839A - Underwater breathing apparatus

Info

Publication number: US3021839A
Application number: US607406A
Authority: US
Inventors: De Loss L Marsh
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-08-31
Filing date: 1956-08-31
Publication date: 1962-02-20
Anticipated expiration: 1979-02-20

Description

UNDERWATER BREATHING APPARATUS Filed Aug. 31, 1956 Q 6' INVENTOR. F 6 '3 F 051055 LM/wsh' BY m M M Anne/v96 fine Patented Feb. 26, 1%62 3,921,839 UNBER NAEER BREATHNG APPARATUS De Loss L. Marsh, 1453 Revere Ave, Hayward, Calif. Filed Aug. 31, 1956, Ser. No. 607,406 6 (Ziaims. (Cl. 128-142) This invention relates to a breathing apparatus. More specifically, this invention relates to a breathing apparatus of the semiclosed circuit type designed for use in skin diving, such as apparatus described in my copending application, Serial No. 512,223, now Patent No. 2,900,977.

Several forms of underwater breathing apparatus, capable of being carried by a diver, have been proposed, the forms being generally classifiable as of the open circuit type and of the closed circuit type.

The open circuit type of underwater breathing apparatus is that type in which air, or oxygen mixed with an inert gas, is stored in cylinders under high pressure (ap proximately 2000 psi.) the cylinders being fastened to the diver. This high pressure air is reduced to an intermediate pressure range (approximately 55-125 psi.) by a first stage pressure reduction valve. The air is obtained by the diver on inhalation through a second demand type pressure reduction valve actuated by respiratory action, with the pressure of the air delivered to the diver being equal to'the existing water pressure at any depth. The entire exhalation of the diver is discharged through his nose and mouth into the water.

The open circuit type has the distinct advantage that it is completely automatic, in that the air supplied to the diver is automatically compensated for pressure difference as the diver rises or descends in the Water. Furthermore, by using air alone, the diver may descend to depths up to 300 feet without danger of oxygen poisoning.

The biggest disadvantage of the open circuit type is its inefliciency. It is well known that the body uses only about one-fifth of the oxygen taken into the lungs on any one inhalation. Thus,even at sealevel or a few. feet under the water approximately four-fifths of the usable oxygen ineach inhalation is thrown away. At a depth of 99 feet air is drawn into the-lungs under a pressure of four atmospheres. Due to the compressibility of air, there is thus four times as much available oxygen in the drawn- ,in air as there would be at sea level, and, consequently,

type. The diver inhales from the breathing bag, through a one way check valve, returning the exhale-d air by way of another one Way check valve to the breathing bag through a canister containing a carbon dioxide absorbent. The rate of oxygen consumed is thus equal to the rate of metabolic consumption of oxygen by the diver. As may be appreciated, this type is highly ethcient as all of the oxygen in the cylinder is utilized by the diver in breathing, with the unconsumed portion being returned to the breathing bag, the carbon dioxide being absorbed to prevent anoxia. With none of the oxygen being wasted a much smaller high pressure cylinder is needed.

The closed circuit type has the disadvantage in that it is not responsive to pressure changes as the diver rises or descends. As the depth increases the diver must reduce the pressure in the bag and readjust the bag volume to are not possible without constant vigilance on the part of the diver. Moreover, oxygen under a pressure of two atmospheres for longer than 45 minutes has an adverse effect on the human body, and thus there is a danger of oxygen poisoning under sustained deep diving when using the closed circuit system.

Applicant has devised asemiclosed circuit to obtain the advantages of the above described systems and at the same time to eliminate the disadvantage of the two systems. That is, the semiclosed circuit described herein incorporates the automatic depth adjusting feature of the open circuit type which increases the efficiency thereof by rebreathing a substantial portion of the air exhaled, and admitting only enough air from a high pressure air reservoir to replenish the oxygen consumed by the body. As has been pointed out above, the body uses only about one-fifth of theoxygen taken into the lungs on any one inhalation. Therefore, it is possible to rebreath substantially four-fifths of the air exhaled, and only approximately one-fifth of an inhalation need be new air admitted to the system; provided, of course, that the carbon dioxide is removed from the rebreathed air.

In the use of the semiclosed circuit, air, or oxygen mixed with an inert gas, is stored in cylinders under high pressure, as in the open circuit. This high pressure air is reduced to an intermediate pressure by a first stage reduction valve, again as in the open circuit. The air is obtained from a breathing bag by the diver through a breathing bag, similar to the closed circuit type. It is of great importance that the breathing bag be smaller than the divers lung capacity, for with each exhalation the larger part of the exhaled air is returned to the breathing bag, with the remainder of the exhaled air being thrown away through an exhaust check valve. On the next inhalation the retained air will be rebreathed along with a quantity of fresh air equal to the amount thrown away. Of course, the exhaled air is passed through a carbon dioxide absorbent in each cycle to remove the poisonous carbon dioxide.-

Since. the semiclosed circuit uses high pressure air, as does the open circuit type, the chances of oxygen poison- :ing is absentyand since only about one-fifth of new air is added to each'inhalation the time limit for the use of the semiclosed circuit for a given capacity air cylinder is approximately five times that of the open circuit.

Further advantages of the semiclosed circuit will become more apparent in the following detailed description.

As the successful operation of the semiclosed circuit depends upon the exhausting of a portion of the exhaled air through the use of a breathing bag of smaller capacity than the lung capacity of the diver, it is seen that the maximum ba-g size that an individual can use will be determined by his lung capacity and the amount of the safety factor desired. That is, each lung full of air at the surface contains enough oxygen for four additional breaths, before all of the oxygen is consumed from the original lung full. This means that for a diver to gain maximum efiiciency at the surface he would require a breathing bag that is four-fifths of his lung capacity so that the other one-fifth of the exhaled air will exhaust through the exhaust valve. This would allow no safety factor and he would be in danger of anoxia should he take shallow breaths. If the diver then descends to a depth of 33 feet in the water, the pressure on the breathing bag and diver will double and twice as much new air will be admitted into the system on each inhalation as compared to surface operation. That is, even though the volume of new air admitted will be the same the double pressure will double the concentration of new air admitted to the breathing bag. With double the amount of new air, the amount of new oxygen'will be doubled inthenext inhalation, and since the metabolic consumpthe bag in expanded position will be somewhat less than four-fifths of the divers lung capacity. As the unde r water depth increases the second bellows 32 will be compressed allowing the breathing bag 13 to expand outwardly to a greater amount reducing the amount of old air expelled through the exhaust valve 26 and consequently less new air will be admitted through valve 28 on collapse of the breathing bag 13 on inhalation. A rigid striker plate 36 is mounted on the movable end wall 21 of the breathing bag 13 to contact the valve stem 29 on collapse of the bag 13. As may be appreciated the second bellows 32' could be mounted on the outside of the movable end wall 21 of the breathing bag so that on expansion of the breathing bag the bellows 32' will butt against the end wall 35 of the housing 23 to limit the bag expansion, without altering the operation of the apparatus.

FIG. 4 illustrates yet another modification of the invention, employing the principle discussed above. In this embodiment the valve stem 29 is adapted to be actuated by a first lever 37 pivoted about a support 38 mounted on the housing 23. A second lever 39, pivoted about support 40 also mounted on the housing 23, has a sealed bellows 41 mounted thereon, the bellows 41 having an end wall 42 adapted to push against the first lever 37 when the breathing bag collapses so as to permit the striking plate 36 to engage the second lever 39. As in the other modification the sealed bellows 41 is filled with air at atmospheric pressure. When the apparatus is used at sea level the bellows 41 will be fully expanded and the breathing bag 13 may only partially collapse before the striking plate 36 engages the second lever 39 to force the end wall 42 of the bellows 41 against the first lever 37 to open the valve 28. As the depth increases the bellows 41 will be compressed and the breathing bag will be allowed to collapse to a greater degree before the foregoing manipulation of valve 28 occurs.

In the foregoing modification, it is obvious that the carbon dioxide removing canister can be located in either the intake or outlet from the face work 11 with the same overall results.

It is to be understood that the forms of the invention, herewith shown and described, are to be taken as preferred examples of the same, and that various changes in the size, shape and arrangement of parts may be resorted to, without departing from the spirit of the invention, or the scope of the attached claims.

Having thus described the invention, I claim:

1. In an underwater breathing apparatus, a collapsible breathing bag having opposed end surfaces, port means in the bag for use in connecting the bag to breathing apparatus, said end surfaces adapted to be relatively positioned adjacent each other on contraction of said bag and away from each other on expansion of said bag, one of said end surfaces having a valve port formed therethrough, a valve having a valve stem extending through said port into said bag, a sealed bellows mounted on the inside surface of the other end, said bellows being adapted to contact said valve stem on contraction of said bag.

2. In a breathing apparatus for use in underwater diving, a collapsible breathing bag being adapted to expand and contract through a limited volumetric change and having opposed ends adapted to be relatively positioned adjacent and then away from each other upon contraction and expansion of said bag, port means in the bag for use in connecting the bag to breathing apparatus, one of said ends having a valve port formed therethrough, a valve having a valve stem extending through said valve port into said bag, lever means mounted in said bag adapted to be engaged by the other end of said bag upon collapse thereof, and means controlling and adjusting said limited volumetric change in direct relation to the underwater depth of said bag and including a sealed bellows attached to said lever means to engage said valve stem upon engagement of and actuation of said lever means by said other end of said bag.

3. In a breathing apparatus for underwater diving, a circulating system comprising a mouthpiece, means for absorbing carbon dioxide, a collapsible breathing bag being adapted to expand and contract through a limited volumetric change and having an expanded volume smaller than the volume of air breathed during one inhalation of the diver using said bag, first tube means connecting said mouthpiece to said carbon dioxide absorbing means, second tube means connecting said carbon dioxide absorbing means to said breathing bag, third tube means connecting said mouthpiece to said breathing bag, an exhaust check valve in said breathing bag, an air storage cylinder, means connecting said cylinder to said system, a normally closed demand valve in said last-named means, said demand valve being operable by said breathing bag upon collapse of said bag to open to permit air from said cylinder to enter said circulating system, and pressure sensitive means for controlling and adjusting said limited volumetric change in direct relation to the underwater depth of said device.

4. A breathing apparatus for underwater diving comprising a mouthpiece, means for absorbing carbon dioxide, a collapsible breathing bag having opposed end surfaces adapted to be relatively positioned adjacent each other on contraction of said bag and away from each other on expansion of said bag and having an expanded volume smaller than the volume of air breathed during one inhalation of the diver using said bag, first tube means connecting said mouthpiece to said carbon dioxide absorbing means, second tube means connecting said carbon dioxide absorbing means to said breathing bag, third tube means connecting said mouthpiece to said breathing bag, one of said opposed end surfaces of said bag having a valve port formed therethrough, a valve having a valve stem extending through said port into said bag, an air storage tank, means connecting said cylinder to said last named valve, a sealed bellows mounted interiorly of said bag on the other opposed end surface, said bellows being adapted to contact said valve stem on contraction of said bag whereby said last named valve is actuated to admit air from said air cylinder into said bag.

5. A breathing apparatus for underwater diving comprising a mouthpiece, means for absorbing carbon dioxide, a housing member, a collapsible breathing bag mounted inside and on one wall of said housing member and having an end movable toward and away from said one wall on contraction and expansion of said bag said bag being adapted to expand and contract through a limited volumetric change; and having a maximum expanded volume smaller than the volume of air breathed during one inhalation of the diver using said bag, first tube means connecting said mouthpiece to said carbon dioxide absorbing means, second tube means connecting said carbon dioxide absorbing means to said breathing bag, third tube means connecting said mouthpiece to said breathing bag, an exhaust check valve in said breathing bag, said one housing member wall having a valve port formed therethrough, a valve having avalve stern extending through said valve port into said bag, an air storage cylinder, means connecting said cylinder to said last named valve, said end of said bag being adapted to engage said valve stem upon contraction of said bag to admit air from said cylinder to said bag, a pressure sensitive means for-controlling and adjusting said limited volumetric change in direct relation to the underwater depth of said bag and including a sealed bellows mounted on an inside wall of said housing member opposite said one wall.

6. A breathing apparatus for underwater diving comprising a mouthpiece, means for absorbing carbon dioxide, a collapsible breathing bag being adapted to expand and contract through a limited volumetric change and having opposed end surfaces adapted to be relatively positioned adjacent each other on contraction of said bag and away 7 from each other on expansion, said bag having a maximum expanded volume smaller than the volume of air breathed during one inhalation of the diver using said bag, first tube means connecting said mouthpiece to said carbon dioxide absorbing means, second tube means connecting said carbon dioxide absorbing means to said breathing bag, third tube means connecting said mouthpiece to said breathing bag, an exhaust check valve in said breathing bag, one of said opposed end surfaces of said bag having a valve port formed therethrough, a valve. having a valve stem extending through said port into said bag, an air storage tank, means connecting said cylinder to said last-named valve, lever means mounted in said bag adapted to be engaged by the other end of said bag upon collapse thereof, and'pressure sensitive means including a sealed bellows attached to said lever means for controlling and adjusting said limited volumetric change inidireet relation to the underwater depth of saidbagfwhereby said lever means Will-engage said valve stem upon engagement of-and actuation of said lever means References Citedin the file of this patent UNITED STATES PATENTS 2,596,178 Seeler May- 13, 1952 2,732,840 De Sanctis Jan. 31, 1956 2,766,753,. K h' Oct. 16, 1956' 2,900,97 Marsh Aug. 25, 1959 FQREIG N PATENTS Great Britain July 13V, 1955