US2820469A - Combined compensated inhalationexhalation valve for pressure breathing mask - Google Patents

Description

Jan. 21, 1958 H. w. SEELER 2,820,

COMBINED COMPENSATED INHALATION'EXHALATION VALVE FOR PRESSURE BREATHING MASK Filed Nov. 29, 1955 2 Sheets-Sheet 1 TEE-T5 uvvsNron MFA/RY W 55 in? H. w. SEELER 2,820,469 COMBINED COMPENSATED INHALATION-EiG-IALATION VALVE FOR PRESSURE BREATHING MASK 2 Sheets-Sheet 2 Jan. 21, 1958 Filed Nov. 29, 1955 United States COMBINED COMPENSATED INHALATIUN- EXHALATION VALVE FOR PRESSURE BREATHING MASK Henry W. Seeler, Dayton, Ohio, assignor to the United States of America as represented by the Secretary of the Air Force The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a valve assembly and, more particularly, to a pressure compensated inhalation and exhalation valve assembly for i pressure breathing in a high altitude mask.

High altitude pressure breathing masks currently in use have three valves built into them. This causes the mask to be unnecessarily large and uncomfortable. The valve assembly in this invention takes over the Work of these valves by compactly combining the functions of an inhalation valve and a pressure compensated exhalation valve. As a result, breathing masks can be made smaller and lighter. This has an important effect on the ability of the wearer to use the mask for long periods of time without discomfort. Accordingly, a principal feature of this inventionis to provide a valve assembly for a breathing mask that combines the functions of an inhalation valve andpressure compensated exhalation valve.

An additional object of this invention is to provide a compact and efficient means for completely pressure compensating the exhalation portion of the vah'e assembly in all pressure ranges.

A further object of this invention is to provide a valve assembly designed so the low temperature oxygen supplied to the valve assembly cannot freeze the exhalation moisture in the valve assembly and cause the exhalation valve to become frozen.

Still another object of this invention is to provide a valve assembly having means for preventing a low pressure drop in the oxygen supply conduit from causing the exhalation valve to open due to the pressure drop.

These and other objects of this invention will become more apparent when read in the light of the accompanying drawings and specification wherein the scope of this invention is defined by reference to the appended claims wherein:

Fig. 1 is a side elevation of the valve assembly disclosing the annular port and showing the mask receiving groove and the oxygen hose receiving stern portion.

Fig. 2 is an end view of the valve assembly disclosing the annular body.

Fig. 3 is a section taken on line 3-4: of Fig. 2.

Fig. 4 is a detail of the valve assembly disclosing the way the exhalation valve is pressure compensated at various pressures.

Fig. 5 is a sectional view of a modified form of a valve assembly and discloses in particular an additional method of preventing a low pressure drop in an oxygen supply conduit from causing the exhalation valve to open due to that pressure drop.

Fig. 6 is an enlarged detail fragmentary sectional view of a portion of a modified valve assembly of 'Fig. 5.

I Fig. 7'is a horizontal sectional view through the tubular exhalation valve support.

Referring to thedrawings by reference numerals and atent ice more particularly to Fig. 3, the compensated inhalation and exhalation valve assembly indicated generally at It comprises an annular tubular housing 12 having an inner end 13 and an outer end 15 (see Figs. 1 and 2). The housing has a tubular stem portion or conduit to adapted to be secured to an oxygen supply hose and an annular mask receiving groove 16 adapted to be inserted in a hole prepared in an oxygen mask. An inhalation chamber 18 and an exhalation chamber 20 in the housing 12 are separated by a movable dividing wall 22 so that the exhalation chamber is at the inner end of the housing 12 and the inhalation chamber is near the outer end. This dividing wall consists of an annular inhalation valve 26 and an annular exhalation valve 24. Valve 24 includes a rigid tubular support portion 21 and a diaphragm 38. The inhalation valve is an annular resilient flexible disc or diaphragm having a centrally disposed axially extending boss portion 28. This boss portion 28 is inserted in a hole 30 in the inhalation cross support member or spider 32. This cross support member is mounted on the inner end 33 of the rigid tubular support portion 21 of the exhalation valve. The periphery of the inhalation valve 26 is adapted to make a one-way sealing contact with the valve seat 34 on the edge of the exhalation valve portion 21 and close oil the port 17 connecting the inhalation and exhalation chambers. As seen in Fig. 3, the inhalation valve opens whenever the pressure in the inhalation chamber exceeds pressures in the exhalation chamber. This equalizes the gas pressures in both chambers. The exhalation valve 24 makes a sealing contact with valve seat 25 annularly disposed on body 12 of. the valve assembly. The exhalation chamber 2% communicates with the ambient air through ports 36 which are opened and closed by the exhalation valve 24. On the opposite end of the exhalation valve portion 21, an annular ring-shaped diaphragm 38is mounted. One edge of this diaphragm is secured to the housing 12 and the other edge is secured to end 35 of the rigid tubular portion 21. The diaphragm is semicircular in cross section in planes perpendicular to the plane of the diaphragm and transverse to its periphery for purposes described below.

An additional cross support member or bridge 37 is mounted in a support member receiving groove 40 in the body of the housing. This cross support member 37 has upstanding projections 42 adapted to maintain light coil spring 44 in position in the housing. Coil spring 44 bears against cross support member 37 at one end and the cross support member or spider 32 at the other end which is mounted on exhalation valve 24. The spring i has the effect of biasing the exhalation valve 24 into a closed position. An additional cross support member or spider do is mounted in the inner end 47 of tubular stem member 14. This support member 46 has a centrally disposed hole 48 adapted to receive the centrally disposed boss 5% of an annular flexible diaphragm inlet valve member 52. This valve member 52 offers little resistance to incoming gases but if the pressure in the oxygen supply hose should drop to a value lower than the pressure of a gas in the exhalation chamber 18, this valve closes making a sealing contact with valve seat 49 on the periphery of the cross support member 46, closing ofi the communication between the inhalation chamber and the tubular supply member 14. This prevents a drop in pressure in the oxygen supply from opening the exhalation or exhaust valve 24. If this valve were omitted, it can be seen that pressure fluctuations in the oxygen supply conduit would cause the exhalation valve to fluctuate between open and closed positions.

The important feature of this invention lies in the way the valve assembly is always completely pressure compensated throughcut all pressure ranges. As seen in Fig. 4-,

the exhalation valve has a surface 27 in the exhalation chamber and a surface 29 in the inhalation chamber. The force F acting on the exhalation valve due to the pressure P in the exhalation chamber is the product of the pressure P multiplied by the projection of the area of the surface 27 on a plane transverse to the direction of motion of the exhalation valve. This area is referred to in this application as the effective area of the exhalation valve in the exhalation chamber. In this case the projection of surface 27 in the exhalation chamber would be circle of diameter D, therefore, the force acting on the exhalation valve due to the pressure in the exhalation chamber is P multiplied by In order to completely pressure compensate the exhalation valve, this force must be opposed by an identical force acting in the opposite direction. Since the gas pressure in both chambers is the same, it follows that the effective areas of the surfaces of the exhalation valve in both chambers must also be the same to balance these pressure forces. This has been accomplished through the use of the ring-shaped diaphragm 38. It has been found that the elfective area of the surface of the exhalation valve in the inhalation chamber can be determined by measuring the circular area surrounded by the apex 39 of the semicircular crosssection of the ring-shaped diaphragm. If the diameter of the apex circle is D, the effective area is Increasing the internal pressure from P to values P or P displaces the ring-shaped diaphragm to the positions indicated by the dotted lines, see Fig. 4. It can be seen, however, that though the cross-sectional configuration of the ring-shaped diaphragm has been altered, the apex diameter distance has not been changed. This apex diameter is made exactly equal to the diameter of the projection of surface 27 in the exhalation chamber. As a result, the pressure forces acting on the exhalation valve are completely balanced in all pressure ranges and the only force necessary to be overcome by exhalation pressure is a slight biasing force on the exhalation valve exerted by spring 44. In other words, this structure keeps exhalation pressure necessary to open the exhalation valve against the force of the biasing spring independent of the gas pressure entering the valve assembly. The result is that with this method of complete pressure compensation, the bias on spring 44 can be very weak. This makes possible a high altitude breathing mask which can be used for long periods without noticeable exertion. In the example disclosed in this case, the exhalation valve was annular and the diaphragm ring shaped. This appears to be the preferable form, but it is within the contemplation of this invention to use other shapes as may be required. For example, the exhalation valve could be oval or square. It is only necessary that the diaphragm be semicircular in cross-section and have one edge secured to the periphery of the valve and the other secured directly to the housing to completely pressure compensate the exhalation valve.

Another extremely important feature of this valve assembly is the radial and axial separation of the inhalation valve 26 from the exhalation valve 24. At very high altitudes, pressurized oxygen entering the mask has a very low temperature. This very cold gas mixes with the moisture from the breath in the exhalation chamber and freezes it. In the separation were not maintained between the inhalation and exhalation valve, the frozen exhalation moisture would freeze the exhalation valve making it inoperative. As seen in Fig. 3, the inhalation valve 26 is mounted 31 closer to the inner end 13 of the hous ing 3.2 than the exhalation valve 24, where the housing has an internal diameter of and where the internal and external diameters of the tubular portion 21 of the exhalation valve at that point are and respectively. This displacement has been found sufiicient to conduct the cold incoming gases away from the warm exhalation moisture adjacent the exhalation valve 24, and prevents the moisture from freezing the exhalation valve throughout all temperature ranges reasonably expected to be en countered. Naturally, the required separation of the inhalation valve and exhalation valve will vary in accordance with the size of the valve.

The modified form of the valve assembly disclosed in Fig. 5 is provided to overcome a possible disadvantage caused by mounting valve 52 at the inner end of the tubular stem or conduit portion 14. As can be seen by reference to Fig. 3, the inhalation chamber 18 is completely sealed between valves 26 and 52, and since the exhalation valve 24 is connected to the valve assembly housing by means of a resilient diaphragm 38, exhalation into the valve assembly decreases the separation between valves 26 and 52 and the volume in the inhalation chamber 18. This decrease in the volume in the inhalation chamber produces an increase in the air pressure in the valve assembly and causes an increase in the force needed to move the exhalation valve 24 out of engagement with valve seat 25 during exhalation. To eliminate this increase in exhalation valve resistance, the modified valve assembly shown in Fig. 5 has been devised.

This modified valve assembly as shown in Figs. 5 to 7 operates in the same way as the valve assembly of Fig. 3 with the exception of the means for preventing a pressure drop in the oxygen supply hose or conduit from opening the exhalation valve. As seen in Figs. 5 and 6, the modified valve assembly includes an exhalation valve having a rigid tubular exhalation valve support 60. This valve support has an integral annular support flange 62 projecting at right angles to the axis of the rigid tubular valve support 60. Uniformly disposed around the periphery of the annular support flange 62 are a plurality of identical upstanding fingers 64, see Fig. 7. These fingers are disnosed perpendicularly to the plane of the annular support flange. An annular coil spring 66 is mounted on the support flange 62 and is held in place by fingers 64, as shown in Figs. 5 and 7. A flat ring shaped valve plate 70 concentric with and reciprocably mounted on valve support 60 rests on coil spring 66. A light coil spring 44, stronger than the coil spring 66, has one end in contact with a ledge 71 on the body 12' and another end in contact with a cross support member or spider 33 on the exhalation valve support 60. This coil spring 44 forces valve plate 70 against valve seat 25' on valve body 12' and also forces the valve plate 70 in abutting relationship with the top edges of fingers 64. The inner edge of annular valve plate has a downwardly depending U- shaped flange 74, see Fig. 6. One edge of a ring shaped sealing diaphragm 72 is mounted in flange 74 while another edge of the diaphragm 72 is mounted in a recess 76 in the support member 60, for purposes to be described below.

In operation, a normal exhalation into the valve assembly exerts a force on the inner surface 27' of the exhalation valve in the exhalation chamber. A portion of this force is exerted on the ring shaped exhalation valve plate 70 and this portion is directly transmitted through the abutting contact between valve plate 70 and the upstanding fingers 64, back to the tubular support portion 60, causing the entire exhalation valve to move just as if the ring shaped exhalation valve portion 70 were integral with the tubular support portion 60. So in normal operation the modified form of the exhalation valve assembly behaves exactly as the valve assembly in Fig. 3.

In the event a pressure drop occurs in the oxygen supply hose or conduit 14', the rigid tubular portion 60 of the exhalation valve will move away from valve seats 25. If the ring shaped valve plate 70 were integral with the rigid tubular portion 60, the exhalation valve would then the bias supplied by the second coil-spring .66 to the: ring shaped valve plate 70. With this arrangemenhas the tubular support 60 moves downwardly, the coil spring 66 maintains the ring shaped valve plate .70 in engagement with the valve seat 25'. Since the ring-shaped valve plate 70 can move with respect to the rigid tubular support member 6%, a sealing diaphragm must be connected between the inner end of the ring shaped valve plate 70 and the rigid tubular support member 60 to prevent leakage between the exhalation chamber and the 'port 36, see Fig. 6. This sealing diaphragm is flexible and U- shaped in cross section to permit the ring shaped diaphragm 70 to move sufficiently far with respect to the tubular support member 60 so it can be held in sealing engagement with valve seat on body 12 when a drop in pressure in the oxygen supply conduit causes the tubular portion of the exhalation valve to move away from valve seat 25.

Having thus described the invention, what is claimed as new to be obtained by Letters Patent is:

1. A compensated inhalation and exhalation valve assembly for pressure breathing in a high altitude mask comprising a housing, said housing having inhalation and exhalation chambers and a port connecting the exhalation chamber with the ambient air, a dividing wall separating said inhalation and exhalation chambers, said dividing wall including an exhalation valve operating to open and close said port, biasing means connected to said exhalation valve for closing said port, said dividing wall further including means for keeping the exhalation pressure necessary to open said exhalation valve against the force of said biasing means independent of the pressure entering the valve assembly.

2. A compensated inhalation and exhalation valve assembly for pressure breathing in a high altitude mask comprising a housing, said housing having inhalation and exhalation chambers and a port connecting the exhalation chamber with the ambient air, a dividing wall separating said chambers, said dividing Wall comprising an exhalation valve adapted to open and close said port, biasing means connected to said exhalation valve for closing said port, said dividing wall having means for equalizing gas pressures in both chambers during inhalation, said exhalation valve having opposed surfaces, one surface in each chamber, said exhalation valve including means responsive to gas pressures for causing the effective area of the surface of the exhalation valve in the exhalation chamber to remain equal to the effective area of the surface of the exhalation valve in the inhalation chamber for keeping the exhalation pressure necessary to open said exhalation valve against the force of said biasing means independent of the gas pressure entering the valve assembly.

3. A compensated inhalation and exhalation valve assembly for pressure breathing in a high altitude mask, comprising a housing, said housing having inhalation and exhalation chambers and a port connecting the exhalation chamber with the ambient air, means for equalizing gas pressures in both chambers, valve means in the housing separating said chambers, said valve means including an exhalation valve for opening and closing said port, biasing means connected to said exhalation valve for closing said port, said exhalation valve having opposed surfaces, one surface in each chamber, and including a rigid tubular support portion and a ring shaped diaphragm, said diaphragm semicircular in cross-section in planes perpendicular to the plane of the ring shaped diaphragm and transverse to its periphery, one edge of the diaphragm secured to the periphery of the tubular portion of the exhalation valve and the other edge secured to the housing, the area of the surface of the exhalation valve in the inhalation chamber surrounded by the apex curve of the cross-section of the diaphragm equal to the effective area of the surface of the exhalation valve in the exhalation chamber, said diaphragm maintaining the effective area of the surface of the exhalation valve in the inhalation chamber equal to the effective area of the surface of the exhalation valve in the exhalation chamber for keeping the exhalation pressure necessary to open said exhalation valve against the force of said biasing means independent of the pressure entering the valve assembly.

4. A compensated inhalation and exhalation valve assembly for pressure breathing in a high altitude mask comprising an annular tubular housing, said housing having inhalation and exhalation chambers and a port connecting the exhalation chamber with the ambient air, a dividing wall in the housing separating said chambers, said dividing wall comprising an annular exhalation valve for opening and closing said port, biasing means connected to said exhalation valve for closing said port, said dividing wall including means for equalizing gas pressures in both chambers, said exhalation valve having opposed surfaces, one surface in each chamber, said exhalation valve including a rigid annular tubular support section and a ring-shaped diaphragm, said diaphragm semicircular in cross-section in planes perpendicular to the plane of the ring and transverse to its periphery, the apex diameter of the surface of the diaphragm in the inhalation chamber equal to the diameter of the effective area of the surface of the exhalation valve in said exhalation chamber, the outer edge of said diaphragm secured directly to said housing, the inner edge secured to the periphery of said rigid annular tubular support portion, said ring-shaped diaphragm maintaining the effective area of the surface of the exhalation valve in the inhalation chamber equal to the effective area of the surface of the exhalation valve in the exhalation chamber for keeping the exhalation pressure necessary to open said exhalation valve against the force of said biasing means independent of the gas pressure entering the valve assembly.

5. A compensated inhalation and exhalation valve assembly for pressure breathing in a high altitude mask comprising a housing, said housing having inhalation and exhalation chambers and a first port connecting the exhalation chamber with the ambient air, a dividing wall in the housing separating said chambers, said dividing wall including an exhalation valve adapted to open and close said first port, biasing means connected to said exhalation valve for closing said port, a second port in the exhalation valve connecting said inhalation and exhalation chambers, an inhalation valve connected to and movable with said exhalation valve operating to open and close said second port to admit oxygen to the exhalation chamber, said inhalation valve spaced from said exhalation valve a distance suflicient to prevent the low temperature of the incoming oxygen from freezing exhalation moisture in the vicinity of the exhalation valve and causing the exhalation valve to become frozen.

6. The apparatus set forth in claim 5 wherein said inhalation valve opens said second port Whenever the pressure in said inhalation chamber exceeds the pressure in the exhalation chamber and maintains the gas pressure in both chambers substantially equal, said exhalation valve having opposed surfaces, one surface in each chamber, said exhalation valve including means responsive to gas pressures for causing the effective area of the surface of the exhalation valve in the exhalation chamber to remain equal to the effective area of the surface of the exhalation valve in the inhalation chamber for keeping the exhalation pressure necessary to open said exhalation valve against the force of said biasing means independent of the gas pressure entering the valve assembly.

7. An inhalation and exhalation valve assembly for pressure breathing in a high altitude mask comprising a housing, said housing having inhalation and exhalation chambers and a port connecting the exhalation chamber with the ambient air, a dividing wall separating said chambers, said dividing Wall including an exhalation valve operating to open and close said port, an oxygen supply conduit communicating with said inhalation chamber, said exhalation valve comprising a rigid tubular valve support, a planar integral support flange extending at right angles to the axis of said valve support, at least one finger integrally secured to said support flange and perpendicular thereto, a valve plate movably mounted on said valve support and positioned to abut against said finger, a valve seat on said housing, first biasing means in said housing operating on said valve support and forcing said valve plate in sealing engagement with said valve seat and in abutting relationship with said finger, a second biasing means in said housing operating between said support flange and said valve plate so that if a pressure drop in said oxygen supply conduit moves said valve support away from said valve seat, said second biasing means will maintain said valve plate in sealing engagement with said valve seat preventing the exhalation valve from opening due to that pressure drop.

Wiggins Oct. 15, 1946 Burns Oct. 28, 1952

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