US 2830583 A
Description (OCR text may contain errors)
April 15, 1958 R. P. FINNEY, JR 2,830,583
ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan. 27 1956 5 Sheets-Sheet l 68 INVENTOR,
m'aw m gr ATTORNEYS" A ril 15, 1958 R. P. FINNEY, JR
5 Sheets-Sheet 2 Filed Jan. 27, 1956 IE-E ATTORNEYS I 6 l l v INVENTOR) OXYGF/V April 15, 1958 FINNEY, JR 2,830,583
ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan; 27, 1956 I 5 ShBQtS-ShGGt 3 ATTORNEYi IN VENTOR April 15, 1958 R. P. FINNEY, JR 2,830,583
ELECTRICALLY CONTROLLED BREATHING APPARATUS Filed Jan. 2'7, 1956 5 Sheets-Sheet 4 AAAAAAIAA I Ivvvvvvv Q) ATTORNEY r'April 15, 1958 R. P. FINNEY, JR- 2,830,583
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ATTORNEY-S 2,830,583 Patented Apr. 15, 1958 fiice A ELECTRICALLY CONTROLLED BREATHING APPARATUS Roy F. Finney, Jr., SheIbyVilXe,'Ind., assignor of forty percent to Charles W. Bailey, Pompano Beach, Fla.
Application January 27,1956, Serial No. 561,820
' Claims. (Cl. 128-142) insuficient to supportlife, and where a portable selfcontained source of breathable air is desirable to permit freedom of movement; v I
In the following specification the apparatus is described as relating particularly to. under-water diving, but it is to be understood that this is not the sole utilization thereof. Referring particularly to -pnder-yvater diving, there are, at present, two commonly used self-contained methods. -'of supplying oxygen todhegdiver topermit: underwater operation without conneeging lines to the surface. The first method, commonly termed theself-contained recirculating method, employs'.a .clpsed; loop breathing unit in which pure-oxygen is breathed over and over again, the carbon dioxide resulting therefrom being continuously absorbed chemically as needed and more oxygen being added manually as needed to compensate for that by the body. 'lhe major disadvantage inherent in this method isthat pure oxygenmay' be poisonous under sufi'icient pressure, and. the use of this. unit is therefore. limited to depths of about 35 feet or less. This method-is, however, very efficient, as nearlyall of the. gas carried. by the diver is-utilized,
The second: method, theself-contau'ned' throw-away method, uses air only which permits its use to depths of several hundred feet without ill effect. Air is basically a mixture of approximately 79% nitrogen which is breathed without being absorbed or changed, and 21% approximately of oxygen, some of which is absorbed by the lungs at eachbreath. The great disadvantage of this throwaway type diving unit is that up to 96% of the compressed air which must be carried by the diver is lost. All of the nitrogen comprising 79% of the total is lost, and nitrogen does not enter into respiration except to dilute the oxygen and prevent oxygen poisoning. Also with the throw-away method up to 80% of the available oxygen is exhaled into the surrounding water and also lost. I From the above it is evident that while the throwaway method allows the diverto go much deeper, it wastes thegreat majority of his air.
A primary object of this invention. is to combine the advantage of both the above units, using a closed recirculating: circuit with" its great'. efiiciency in the utilization of breathable gases and allowing the user to breathe air instead of pureoxygen and therebyachievemuch greater depths safely. Provision is made for an apparatus of the recirculating type in which the user breathes air or a mixture of oxygen and nitrogen approximating that found in air; employing particularly a means forautomatically replacing the oxygen consumed by the bod'y and a means for absorhing the carbon dioxide content-"of the breathable atmosphere. Devices have previously been made which allow a constant pre set flow of oxygen to the divers breathable atmosphere, but this has been unsatis factory since the oxygen requirement of a diver may in-- crease 10 times, depending on how strenuously he exer= cises, the temperature of the water and other factors. The device herein described automatically meters the proper amount of oxygen into the closed system regardless of the changing oxygen requirements of the diver.
An additional object of the invention is the provision of a simplified and improved apparatus of this character which may readily be carried on the back of a diver to simplify ascent and descent into relatively deep water, without discomfort or danger.
Still another object of the invention resides in the provision of a Wheatstone bridge type gas thermalconductiv-ity cell including an electrical impulse means and other electrical device for the purpose of automatically regulating the oxygen relative to the air or nitrogen supply.
A more specific object of this invention is the provision of a method. and means whereby the chambers or compartments in the gas thermal-conductivity cell of the Wheatstone bridge are kept at substantially equal pressures while the external hydrostatic pressures, to which the gas pressures in the compartments are responsive, undergo changes corresponding with changes in depth of water; such equalization of pressures being accomplished without mixing the gases in the compartments, which compartments are non-communicative with each other.
An additional object of the invention resides in the provision of means whereby a mixture of an inert gas, such as helium in the ratio of about to 20% of oxygen may be employed in lieu of the conventional air mixture. The use of helium instead of nitrogen as the diluting gas has numerous advantages well known to those versed in the art of diving such as prevention of both caisson disease and nitrogen narcosis.
Yet another object is the elimination of bubbles escaping from the device at each breath as with the throwaway type unit. These bubbles are undesirable since they give warning to an enemy when such diving devices are used for military purposes and they scare fish when used for sport purposes.
Still other objects reside in the combinations of elements, arrangements of parts, and features of construction, all as will be more fully pointed out hereinafter and dis-closed in the accompanying drawings wherein there is shown a preferred embodiment of this inventive concept.
In the drawings:
Figure l is a partially schematic sectional view of one form of device embodying features of the instant in-- vention, the wiring between the electrical elements being shown.
. Figure 2 is a schematic sectional view of certain of the interior elements of the apparatus.
Figure 3 is a perspective view disclosing the outer assembly-of the device as applied to the person of a swimmer or the like.
Figure 4 is a rear elevational view of the device of Figure 3.
Figure 5 is a sectional view taken substantially along the line S-5 of Figure 4.
Figure 6 is a diagrammatic schematic view of the electrieal circuit incorporated in this apparatus.
Figure 7 is a view of the gas thermal-conductivity cell showing the bridge resistance members and their location in the cell chambers.
Figure 8 is a side elevation ofthe gas' thermal-conductivity cell taken along the line 8-8 of Figure 7.
Figure 9 is a cross sectional view taken along the line 9--9 of Figure 7 showing also the port connections.
brackets 14 secure to the opposite side of the receptacle an oxygen tank 16. From the upper sides of receptacle '11 extend an air inhalation tube and an exhalation tube 21. The upper part of receptacle 11 is provided with a supplemental member 17, having perforations 18, to permit the ingress of water under pressure to a pressure susceptible water-tight air-containing bag' 19 (see Fig. 2). The oxygen tank 16 communicates with the interior of receptacle 11 by means of a standard oxygen cut-off valve 22 and pressure reduction valve 28 and flow adjustment valve 26, to be more fully described hereinafter, while the air tank 15 correspondingly communicates with the interior of the receptacle by means of standard cut-off valve 23 and valve 25, the purpose of which will be more fully described hereinafter.
Having reference now to Figure 2, the pressure responsive bag 19 is adapted to be filled with air from tank 15.
The air passes through a manually controlled valve 25 and a tubular member 27, which opens directly into the chamber receptacle 11, and from this receptacle the air goes into the bag 19 by way of port and its tubular member 39. Oxygen from tank 16 is supplied through a cut-olf valve 22, pressure reduction valve 28, a flow adjustment valve 26', and a solenoid-controlled valve 29 and tube 30 to the bag 19. Air withdrawn from the bag 19 passes through a Venturi or other suitable arrange- 'ment 31 to a flexible tube 20 and vents through a check valve 33 (Fig. 2) to a face mask or mouth-piece 34. Exhaled air thence passes through the a check valve .35 and flexible tube 21 to a container 37, adapted to eliminate the carbon dioxide by means of any suitable chemical such as soda lime 38 and then through a tubular member 39 back to the bag 19 for reutilization.
Venturi tube 31 is closely joined to a Wheatstone bridge 42 adapted to detect, by means ofdifiering gas thermal conductivities the concentration of oxygen relative to a suitable diluting gas such as nitrogen. Venturi tube 31 is adapted to draw a new quantity of air from bag 19 during each inhalation of the diver through bridge chamber 42A by means of a pair of tubular members 43. The Wheatstone bridge used in the thermal-conductivity cell, as best shown in Figures 2, 6, 7, 8, and 9 comprises opposite pairs of resistance members 44A and 44B, the resistor pair 448 being enclosed in suitable connecting receptacles 428 containing normal air while resistor pair 44A is enclosed in similar receptacle 42A containing air drawn from Venturi tube and bag 19 as heretofore described. When the bridge is adjusted in a manner to be more fully described hereinafter a current flows through wires 45 and 46' to current interrupter 47 and thence through wires 48 and 49 to an alternating current amplifier 50 whose output causes relay 95 to cut oil electrically operated gas valve 29. During respiration when the oxygen concentration of bag 19 falls below that desired, the current from the Wheatstone bridge decreases and the input and hence output of the amplifier 50 also decreases causing relay 95 to open solenoid type gas valve 29 in oxygen line 30 transmitting additional oxygen to the system to replenish the oxygen absorbed by the lungs. When the oxygen concentration has risen to the desired degree the bridge output rises causing the solenoid valve 29 to shut the oxygen off. Electric current to operate the bridge, interrupter, amplifier and solenoid is supplied by suitable batteries 67, 68, 69, and 70. For purposes of explanation, the diagrams illustrate the use of a vac- U and solenoid valve 29.
uum tube alternating current amplifier of conventional design and an interrupter to pulse the direct current from the bridge. A direct current amplifier, such as one using transistors, can readily be adopted and is highly desirable because of its small size, low current consumption and the elimination of the interrupter.
It is to be noted that the oxygen inlet line is provided with a suitable pressure reduction valve 28 and gauge 6'1 and fiow control valve 26 between oxygen tank 16 There are seen in Figure 1 suitable batteries as indicated at .67, which indicates a bridge battery while 68 discloses an interrupter battery, 69 an amplifier battery, and 70 a solenoid battery. At 71 there is shown a small flexible rubber bag under no tension which contains the standard gas, either air or the above-mentioned mixture of helium-oxygen, connected by means of a tube 72 to the container 42B, in communication with the standard legs of the bridge, thus maintaining the standard legs of the bridge filled with the standard gas, and also maintaining an equal pressure on all four legs of the bridge. The pressure on legs of the bridge in chamber 42A is maintained equal through the pathway from bridge chamber 42A up through tubular member 43 to the Venturi tube 31, thence into bag 19 and thence through tubular member 39 and port 40 into the interior of receptacle 11. This pressure equalization is freely transmitted through the flaccid rubber bag wall 71 and through tubular member 72 to bridge chamber 42B. This maintenance of equal pressure is important in that any increase in-the gas'pressure of one pair of legs over that in the other will affect the operation of the bridge and is highly undesirable. Rubber bag 71 assures that chambers 42B are always'filled with a standard'gas such as air.
In Figure 1 there is disclosed-a means of precluding the admission of moisture'condensing in the outlet tube 21 from being readmitted to the system and comprises a washer 75 positioned interiorly of the tubular member 21 and a by-pas tube 76', which in turn leads to a condensation chamber 77 provided with 'a spring biased valve 78 which is adapted to open to release moisture from the trap 77 when the pressure in the'system rises sutficiently to force the valve open against the pressure exteriorly thereof. There is also disclosed in Figure -1 a" standard oxygen fixture 80 including a manually operable valve 25, operated by a lever 82 to admit the air mixture initially into the system. Other uses of valve 25 are described hereinafter.
Figures 7, 8, and 9 disclose in some detail the arrangement of the Wheatstone bridge type thermal-conductivity cell. The container 42 surrounding the legs of the bridge is composed of a high heat conducting material such as brass which serves to surround the legs with the same thermal environment. Bridge chambers 42A are interconnected by passage and bridge chambers 42B are connected by passage 101. The two pairs of chambers are supplied with inlet and outlet tubular members 102 which allow gases to be admitted. The resistance members 443 which are commonly made of fine platinum wire are centered in their individual chambers 4213 by supports 104 which are insulated by suitable material 105 (Fig. 8). One of the tubular members 102 of chambers 42B is plugged after this chamber and bag 71 are filled with the standard gas.
Figure 6 discloses in schematic form the electrical connection of the device. In practice, the Wheatstone bridge 42 detects changes in the thermal conductivity of gas mixtures, in this case oxygen and either nitrogen or helium. All of these gases has difierent rates of thermal conductivity. A steady current from battery 67 is passed through all legs of the bridge causing them to be heated. .With air in both pairs of chambers the bridge is adjusted by variable resistance R until the output current in connections 45 and 46 is of some suitable value. This direct current is pulsed by electrically operated vibration interrupter 47 and is then passed through the primary 91 of a step-up transformer generally indicated at 92. The alternating output of transformer 92 is fed into the control grid of a suitable pentode tube 93. The amplifier isotherwise of conventional alternating current type with a gain control following the first stage of amplification and a relay 95 in the final plate circuit. The gain control is so adjusted that with air in both pairs of bridge chambers 42A and 42B, the relay 95 just closes. The closing of relay 95 causes the solenoid coil 55 to be deenergized and the solenoid operated gas valve 29 is cut off. The electric gas valve 28 is normally closed when deenergized. When respiration begins and as oxygen is removed from the closed system by the lungs the increasingly oxy gen poor air is drawn into chamber 42A by tubular members 43 and Venturi tube 31. (See Fig. 2.) Chamber 42B is kept filled with pure air at all times as previously described. The two detector legs 44A of the bridge, being new surrounded by nitrogen and less oxygen than is found in air, begin to lose heat at a difierent rate than the two legs 44B surrounded by pure air. This heat. loss of legs 44A causes them to change in temperature and, therefore, in resistance, which in turn causes a current decrease in the bridge output passing through connections 45 and 46. This decreased input to the amplifier produces a decreased output and relay 95 (Fig. 6) drops out or releases its armature. The release of the armature closes the solenoid coil 55 circuit energizing the gas valve 29 and admitting oxygen to the system to replace that removed in respiration. When the oxygen has risen to the same relative concentration as that found in air, the bridge output rises causing relay 95 to close and oxygen valve 29 to cut ofi. The cycle is repeated over and over, always maintaining the relative oxygen concentration close to a constant value.
The use of electronic amplification is needed with an oxygen-nitrogen mixture in the closed system since these two gases have close rates of thermal conductivity and the bridge output is, therefore, quite insufiicient to operate the relay directly.
It should here be pointed out that the amplifier is necessary only when air is employed in the system. When a mixture of 80% helium and 20% oxygen is employed no amplification is needed and the bridge output is sufiicient to operate a moderately sensitive relay directly, because the ditference in thermal conductivity is much greater with helium and oxygen than with nitrogen and oxygen and the bridge output is consequently much greater. again and again in the closed system, thus increasing'the efificiency from about 4% as found in the throw-away type breathing device to nearly 80% and, since almost all the oxygen is utilized, the over-all efiiciency approaches 100%.
From the foregoing the use and function of the apparatus should now be readily understandable. The device is first positioned on the back of the users and held in position by means of the shoulder straps 12 and the face mask or mouthpiece 34 placed in position. Air is admitted to the device by actuating manually controlled valve 25, the air passing into container 11 and through open port 40 (Fig. 1) into the bag 19. The gas bag is thus partly filled with air, and valve 25 is then closed. The pressure inside the case is maintained at the same pressure as the outside water regardless of depth since this pressure is transmitted from the water to the air in bag 19 and through port 46} (Fig. 1) to the interior of the case 11. This makes it unnecessary for the water-tight case to withstand the high pressure found at depths. Air is drawn from bag 19 on inhalation through the venturi tube 31, and thence to the mouthpiece. A very small part of the gases passing through the venturi is diverted to the Wheatstone bridge cell 42, which is close to the Venturi. Thus samples of the bag gases or air are repeat- In this device, the same nitrogen is breathed edly: carried through the two detector legs 42A of the bridge. The other two legs are connected to the flexible rubber bag 71, which bag is partly collapsed, or at least not under any tension or internal pressure. This bag keeps the legs of the bridge filled with the standard gas, and co-operates to maintain the four legs at the same pressure. The air which is taken from the bag 19 on inhalation, when exhaled, contains the same amount of nitrogen as when inhaled, plus carbon dioxide, and about one fourth less oxygen. The exhaled air passes to container 37 and the carbon dioxide is there absorbed. The check valves 33 and 35 serve to control the direction of the air as exhaled and inhaled. The exhaled air then passes into the breathing bag 19. After this cycle is repeated a few times, the concentration of oxygen in bag 19 decreases slightly and causes enough change in the output of the Wheatstone bridge to actuate amplifier 50, causing solenoid 55 to open valve 29 and admit additional oxygen to the system. The valve 26 is pre-set so that the infiow of oxygen into the closed system is at the same rate asthat used by the body at maximum exercise As the oxygen continues to flow into the bag 19 the concentration rises and, when it has reached the desired degree, the Wheatstone bridge again changes sutficiently in output and the solenoid valve is shut off.
As a diver descends the external water pressure increases causing a decrease in the volume of the breathable gas in bag 19. As this occurs the diver uses lever valve 25 to add more air or other breathable gas to the system to maintain an adequate volume. Buoyancy of the entire system can also be controlled to some extent by this means. As a diver ascends the external water pressure decreases and the volume of the gas in bag 19 increases. When the limits of expansion of bag 19 have been passed the pressure in the entire system begins to exceed the pressure of the surrounding water. At this point spring biased valve 78 is forced open and any excess air is allowed to escape. The loss of this gas on ascent is the only time any gas is allowed to leave the closed system. Oxygen is supplied only as needed and the nitrogen in the air is used over and over since its only purpose is that of a diluting agent to prevent oxygen poisonmg.
From the foregoing it will now be seen that there is herein provided a novel electrically controlled breathing apparatus, particularly adapted for under-water use which accomplishes all the objects of this invention and others, including many advantages of great practical utility and commercial importance.
Since many embodiments may be made of this inventive concept and since many modifications may be made in the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limited sense.
What I claim is:
1. An under water breathing apparatus comprising a closed respiration circuit having a flexible breathing bag for exposure to external water pressure when in use, an oxygen supply unit connected to said circuit, a supply unit of other breathing gas connected to said circuit, a flexible gas container for exposure to external water pressure when in use and non-communicative with said closed respiration circuit, electrically controlled means for regulating the supply of oxygen to said respiration circuit, said means comprising a thermal conductivity cell of the Wheatstone bridge type having a compartment in communication with said closed respiration circuit and containing at least one arm of the Wheatstone bridge and another compartment non-communicative with the first-named compartment and in communication with said. flexible gas container and enclosing at least one other arm of the Wheatstone bridge, and electrically operated valve mechanism between the oxygen unit and respiration circuit and responsive to change in E. M. F. across the Wheatstone bridge.
2. An underwater breathing apparatus comprising a closed respiration circuit containing a flexible breathing bag for exposure to external water pressure, a face piece, an inhaling conduit from said breathing bag to said face piece, an exhaling conduit from said face piece to said breathing bag, an oxygen supply unit, electrically controlled means including a source of electricity, an electrically-operated gas valve and a Wheatstone bridge type thermal conductivity cell in said inhaling conduit and adapted to receive samples of inhaled gas at each inhalation for controlling oxygen delivery from said supply unit to said respiration circuit, said cell having a closed compartment in communication with a flexible gas container for exposure to external water pressure when in use and non-communicative with said closed respiration circuit and containing one pair of alternate arms of the Wheatstone bridge, another compartment of said cell being in communication with the inhaling con duit of said closed respiration circuit and containing the other pair of alternate arms of the Wheatstone bridge, means for passing over the latter pair of alternate arms of the Wheatstone bridge, at each inhalation of the breathing gas, the sample of said breathing gas, and means for transmitting a change in the E. M. F. across the Wheatstone bridge to the electrically-operative mechanism of said gas valve.
3. The combination claimed in claim 2, together with means in said inhaling conduit for forcing, at each inhalation, a sample of the breathing gas into the second-named compartment of the cell and over the alternate arms of the Wheatstone bridge therein.
4. The combination claimed in claim 2, together with means comprising a Venturi in said inhaling conduit for forcing, at each inhalation, a sample of the breathing gas into the second-named compartment of the cell and over the alternate arms of the Wheatstone bridge therein.
5. The combination claimed in claim 2, together with means comprising a Venturi in said inhaling conduit for forcing, at each inhalation, a sample of the breathing gas into the second-named compartment of the cell and over the alternate arms of the Wheatstone bridge therein, and
means in said exhaling conduit for removing CO from the exhaled gas before its return to said breathing bag.
References Cited in the tile of this patent UNITED STATES PATENTS 1,783,451 Rabinowitch Dec. 2, 1930 2,323,675 Rand July 6, 1943 2,414,747 Kirschbaum Jan. 21, 1947