US 3189027 A
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June 15, 1965 BARTLETT, JR 3,189,027
ANTI-SUFFOCANT APPARATUS FOR OXYGEN SUPPLY SYSTEMS Filed Nov. 29, 1962 OXYGEN 44 SUPPLY INVENTOR.
Roscoe G. B lefl, Jr. BY
gasping will likewise open this valve.
United States Patent Ofiice 3,189,927 Patented June 15, 1965 3,139,027 ANTI-SUFFQCANT APPARATUS FQR OXYGEN SUPPLY SYSTEMS Roscoe G. Bartlett, Jr., Lime Kiln, Md.
Filed Nov. 29, 1962, Ser. No. 241,083 Claims. (Cl. 128-142) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates generally to apparatus for sustaining flight personnel exposed to environments the oxygen content to which is insufficient for their normal respiratory requirements and, more particularly, to a safety attachment for an oxygen pressure mask which automatically permits the wearer to inspire air from the local atmosphere when his oxygen supply has been expended. V
In one type of conventional oxygen supply system for high altitude use, oxygen in one mode of operation is delivered to the facemask under pressure to ease the wearers respiratory efforts. However, when the oxygen supply is depleted, the individual usually must remove his mask before he can inspire air from the surrounding atmosphere. If he is unconscious or otherwise disabled at this time, he may, of course, suffocate, notwithstanding the fact that he may be in an environment which can satisfy his oxygen requirements.
It is accordingly a primary object of the present invention to provide an attachment for a facernask of the type used in an oxygen supply system which automatically switches the mask from the oxygen source when the supply of oxygenis exhausted to the local atmosphere.
Another object of the present invention is to provide a lightweight, compact, safety bypass valve that can be mounted on a conventional oxygen-pressure facemask so as to automatically couple the mask to the local environment when the oxygen supply is depleted.
A yet still further object of the present invention is to provide apparatus for use with an oxygen mask which functions even when the individual wearing the mask is unconscious to switch the input torthe mask from the oxygen supplywhen this supply is used up to the local atmosphere.
A yet still further object of the present invention is to provide a safety. feature for an oxygen mask used in a pressure-breathing system which responds to the wearers respiratory action to effectively couple the mask to the local atmosphere when the oxygen supply in thesystem is expended.
Briefly and in somewhat general terms, the above objects are realized in one embodiment of the invention by attaching a lightweight, compact, safety bypass valve to the breathing tube section of a facemask designed for pressure breathing. As long as there is a flow of oxygen from the oxygen supply source into the facemask, this bypass valve remains in its closed position. However, when the oxygen supply is exhausted, the wearer's inhalation elforts by themselves automatically open the bypass valve, thereby coupling the local atmospheric environment to the breathing tube section of the facemask. If the individual in unconscious at this critical time, his A snap-acting mechanism is included in the valve assembly to give it a positive type of action. Additionally, the apparatus has a reset device which permits the wearer to manually control the condition of the bypass valve.
Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in con junction with the accompanying drawings wherein:
FIG. 1 schematically illustrates one embodiment of the present invention applied to a facemask designed for pressure breathing; and
FIG. 2 shows the details of a part of the snap-acting feature of the safety bypass valve of FIG. 1.
Referring now to FIG. 1 of the drawings, which illustrates the application of the present invention to an oxygen supply system for flight personnel, a conventional facemask 1, designed for pressure breathing and fabricated of molded rubber, .for example, is provided at a lower portion thereof with a flexible breathing tube section 2 and an exhaust port 3. In the particular mask configuration selected for illustration, only the nose and mouth of the wearer are covered. However, it should be readily appreciated that additional coverage may be included for the complete head of the wearer. Breathing tube section 2 in one design is closed at'its remote end by a wall 4 which has a central aperture formed therein through which passes nozzle 6 of a conventional pressure-compensated exhaust valve 7.
In one prior art construction, this exhaust valve has as its control device a piston 11 which is normally biased by coil spring 12 to its closed position up against valve seat 13. Nozzle 6 leads to the bottom side of this piston and, as will be seen hereinafter, prevents this valve from opening except during the exhalation portion of the wearers breathing cycle. This valve is mounted in a transverse wall 8 which partitions off the bottom portion of the mask from the facemask area. Also built into this mask are a pair of air passageways 9, only one of which is shown, which lead from breathing tube section 2 into the face mask area. Each of these passageways terminates in a nonloaded check valve which allows only acne-way gas flow into the facemask area.
In the normal operation of the oxygen supply system, oxygen from the high pressure supply source, after a pressure reduction, flows into breathing tube section 2 through passageways 9 and check valves 10 into the respiratory system of the individual wearing the facemask. During the expiratory portion of the latters breathing cycle, his discharge opens exhaust valve 7 and passes via exit port 3 out into the atmosphere.
The anti-suffocant bypass valve of the present invention, generally represented by reference character 14, is attached to the breathing tube section 2 of the facemask by a suitable clamping device 15. Bypass valve 14 includes a housing 16 which is closed at its top portion by a cover plate 17 that has a plurality of ports 18 cut therethrough at one location and a single aperture 19 formed therein at a second location. Clamping device establishes an airtight fit between the lower portion of breathing tube 2 and a sleeve 16 which locks into the latter aperture.
Mounted on the top surface of cover plate 17 is a sleeve 20 whose inner top wall portion is threaded 'to receive a cap 21. This sleeve has an external flange 22 formed at its lower end which is locked under a clamping plate 23 that is fastened by suitable screws 24 to the top wall of housing 16. Closure cap 21 has a plurality of apertures 25 and a centralaperture 26 formed in its central top wall portion. Passing through the latter aperture and through cover plate 17 is a push or reset rod 27 which is secured at a point intermediate its length to a circular piston 28.
Also positioned within sleeve 20 is an elastic bellows 29 which fits into a cutout portion formed in the bottom rim of cap 21. When piston 29 is in its upper or closed position, it compresses bellows 29 and forms an airtight seal with the bottom end thereof. A bias spring 30 is also included in the apparatus with its top portion abutting the bottom wall of cap 21 and its bottom portion resting on piston 29. This spring, which controls the opening pressure of the safety bypass valve, has insufiicient force by itself to move piston 23 downwardly to unseat it from element 29 whenever a positive pressure exists within housing 16.
It would be pointed out that push rod 27 is free to move up and down through the apertures in closure cap 21 and cover plate 17 and, when it-does so, piston 28 moves along with it. When piston 28 moves downwardly from the position shown, the contact between its peripheral surface and the lower rim of bellows 29 is not immediately broken because of the expansion of bellows 29. This action, as will be seen hereinafter, insures the positive opening of the bypass valve,
When piston 28 finally does break contact with the lower rim of bellows 29, air can be drawn from the outside atmosphere through ports 25 into the top half of sleeve 20, around the rim of piston 28 into the bottom half of the sleeve, and thence via apertures 18 into the central portion of housing 16. From here it can pass directly into the breathing tube section 2 and the face mask area.
As best shown in FIG. 2, push rod 27 has a slot 31 cut therethrough near its bottom end. Passing through this slot and extending a short distance beyond is a lever 32 which is mounted for pivotable movement about a shaft 33 journalled into a pair of ears 34 formed in a post 35 that extends upwardly from the bottom wall of housing 16. Lever 32 carries at its remote end a cross bar 36, and a pair of springs 37 under tension are connected between the ends of this bar and a pair of extension arms 38 projecting from both sides of post 35. It will be recognized that lever 32 and its affiliated spring components constitute a snap-acting mechanism that positively displaces piston 28 to either its open or closed condition once this lever passes over its center or horizontal position.
Secured to the bottom wall of housing 16 is a pressure reducer 39 which functions to reduce the oxygen pressure to a level that is not injurious to the respiratory system of the individual. Pressure reducer 39, which is of conventional design, produces a low pressure flow from its output side into the central portion of housing 16 via a plurality of apertures 41 and a smaller flow into nozzle 6 of pressure-compensated valve 7 via its nozzle 42 and a flexible tubing 43 connected therebetween. This last connection provides the pressure compensation for exhaust valve 7 and prevents the oxygen normally flowing into the facemask area via breathing tube section 2, passageways 9 and check valves from depressing piston 11 and thus passing out unused into the atmosphere via exit port 3.
The operation of the apparatus of FIG. 1 is as follows: To prepare the equipment for use, push rod 27 is first moved to the position shown, thereby closing the antisuffocant bypass valve 14. When pressure or demand breathing is initiated, oxygen flows from source 44 via line 40, out of ports 41 into the breathing tube section 2 of the facemask and, thence, via passageways 9 and check valves 10 into the respiratory system of the individual. During the expiratory portion of his breathing cycle, his discharge opens pressure-compensated valve 7 and passes via port 3 out into the atmosphere. The oxygen flow from ports 41 also maintains a positive pressure within the central portion of housing 16, and this pressure, acting upon the bottom surface of piston 28, insures the closed condition of bypass valve 14. Thus, the oxygen breathing system is isolated from the atmosphere except during the exhalation portion of each breathing cycle.
When the oxygen source is depleted, the individual depresses push rod 27 downwardly to open bypass valve 14 and allow air from the outside environment to enter the facemask to satisfy his breathing demands. However, if he is unconscious or otherwise disabled at this time, his continued breathing action will also bring about the same result because the negative pressure developed by his gasping will first open check valves 10 and then bypass valve 14. More paiticularly, when his breathing efforts create a negative pressure within housing 16, piston 28 is pulled downwardly until lever 32 passes just beyond its center or horizontal position. Spring 30, of course, assists this action. As piston 28 moves downwardly, elastic bellows 29 expands and, in effect, follows the piston to hold the valve closed until lever 32 moves beyond the above position. If this bellows were not present, as soon as piston 28 moved off its seat the pressure would fall and the valve would not go over center to stay open. Once lever 32 moves beyond the over center position, springs 37 act to snap piston 28 quickly to its completely open position and lock it in this condition. With bypass valve 14 now open, air from the outside can be drawn via ports 25 and 18 into housing 16 and thence via breathing tube section 2 and facemask 1 into the individuals respiratory system.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
What is claimed is:
1. An anti-sulfocant safety valve for an oxygen supply system of the type wherein oxygen from a supply source enters a supply line leading into the interior of a facemask comprising, in combination,
a sleeve connected to an exterior wall of said chamber and having one end thereof communicating with the interior of said chamber;
a piston positioned within said sleeve and having a diameter less than the interior diameter of said sleeve:
an over-center, snap-acting switching mechanism connected to said chamber and to said piston for moving said piston between an upper and lower position within said sleeve;
a bellows open at both ends thereof;
said bellows having one end thereof connected to the top of said sleeve and the other end extending downwardly to a position slightly beyond the mid-point between the upper and lower positions of said piston whereby said bellows contacts said piston to form an airtight seal therewith from the upper position of said piston to a position slightly beyond said midpoint and is spaced from said piston When said piston in in its lower position,
and means defining an air passageway between said chamber, said supply source and said supply line whereby whenever a negative pressure is created in said supply line in response to the inhalation efforts of an individual wearing said facemask, said piston is drawn downwardly from its upper position until said over-center, snap-acting switching mechanism suddenly activates it to its lower position whereby air from the atmosphere can thereafter be drawn through said sleeve and into said chamber for use by the individual wearing said facemask.
2. In an arrangement as defined in claim 1,
a push-rod connected to the top of said piston,
said push-rod extending beyond the other end of said sleeve for permitting said piston to be manually moved between its upper and lower positions with said sleeve.
3. In an arrangement as defined in claim 1,
a closure cap covering the other end of said sleeve,
said closure cap being provided with a multiplicity of apertures which permit air from the atmosphere to be drawn into said sleeve,
said closure cap having a circular recess cut in the rim portion thereof for accommodating the end of said bellows which is connected to the top of said sleeve.
4. In an arrangement as defined in claim 3,
a helical spring disposed between said closure cap and the top of said piston,
said helical spring being maintained under compression when said piston is in its upper position and having insufi'icient force to displace said piston to its lower position whenever the pressure within said chamber is greater than the adjacent atmospheric pressure.
5. An anti-sutfocant safety valve for an oxygen supply system of the type wherein oxygen from a supply source flows into a supply line leading into the interior of a facemask comprising, in combination,
a sleeve extending upwardly from an exterior wall of said chamber with one end of said sleeve communicating with the interior of said chamber;
a piston accommodated within said sleeve;
said piston having a diameter that is less than the interior diameter of said sleeve whereby an air passageway exists between the inner wall of said sleeve and the rim of said piston;
an over-center, snap-acting switching mechanism mounted in said chamber and connected to said piston for displacing said piston between an upper and a lower position within said sleeve;
a flexible, tubular bellows disposed within said sleeve,
one end of said bellows being connected to an inner wall portion of said sleeve adjacent the other end' thereof,
- 6 a the other end of said bellows terminating at a position which is slightly beyond the mid-point between the upper and lower positions of said piston whereby said other end of said bellows contact said piston to form an airtight seal therewith while .said piston is in its upper position and as it moves to said. position slightly beyond said mid-point and whereby said bellows is spaced from said piston when said piston is in its lower position; and means for coupling said chamber to said supply line and said supply source whereby whenever a negative pressure is created in said chamber in response to the inhalation eiforts of an individual wearing said facemask said piston is drawn downwardly from its upper position until said over-center, snap-acting switching mechanism suddenly activates it to its lower position whereby air from the atmosphere can thereafter be drawn through said sleeve and into said chamber for use by said individual.
References Cited by the Examiner UNITED STATES PATENTS 1,610,500 12/26 Eggleston 25 l280 X 2,416,411 2/47 Sharbaugh et a1 128146 2,598,525 5/52 Fox 128-142 X 3,092,104 6/63 Cassidy l28142 30 RICHARD A. GAUDET, Primary Examiner.