US2970593A - Mask-harness tension compensating device - Google Patents

Description

Feb. 7,1961 H. W.SEELER MASK-HARNESS TENSION COMPENSATING DEVICE Filed May 6, 1957 2,970,593. MASK-HARNESS TENSION COMPENSATING DEVICE Henry W. Seeler, Dayton, Ohio, assignor to the United States of America as represented by the Secretary of the Air Force Filed May 6, 1957, Ser. No. 657,461 4 Claims. (Cl. 128-142) (Granted under Title 35, US. Code (1952), see. 266) 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 device for regulating the tension of the harness connecting a breathing mask to a headgear and, more particularly, to a device that automatically regulates the tension of the harness connecting the breathing mask to the headgear in accordance with the ambient pressure.

In connecting a high altitude oxygen breathing mask to a headgear by a harness, it is necessary to adjust the tension of the harness at ground level so that the mask is leak proof not only at demand breathing, but also at pressure breathing up to fourteen inches of water, the later condition existing at high altitudes. The harness tension, which is required to insure that there is no leakage about the mask at high altitude, is sufiiciently large that it creates an uncomfortable mechanical pres: sure around the face of the wearer and especially in the nose area.

One method of alleviating this problem of an uncom fortable fit of the mask against the face of the wearer when large harness tensions are not required it to use a manual adjustment of the harness connection to the mask. This has the problem of requiring a manual actuation; the high speed of jet aircraft, for example, requires such constant attention of the pilot that even the slight diversion to manually adjust the mechanism may create an accident hazard. This manual adjustment also has only one variation in the tension of the mask harness whereby a greater tension of the harness is employed before it is needed to seal the mask against the face of the wearer.

The present invention satisfactorily solves these problems by requiring only a small harness tension at ground level to make the mask leak proof during demand breathing. While this small harness tension furnishes the seal during demand breathing, only a slight pressure exists on the wearers face so that the mask is substantially comfortable. As the aircraft gains altitude, the present invention increases the harness tension in response to the decrease in ambient air pressure. This results in the mask tightening against the wearers face as the altitude increases, but it does not increase the pressure of the mask against the wearers face substantially beyond that required to insure a seal between the mask and the wearers face. When very high altitudes are encountered, the harness tension is increased further so that a large pressure is created by the mask against the wearers face to thereby seal during pressure breathing at large vacuums. However, as soon as the altitude decreases, the harness tension reduces accordingly.

An object of this invention is to provide a device for automatically adjusting the tension of the harness ofa breathing mask according to the ambient altitude.

Another object of this invention is to provide a device thatincreases the force holding the breathing mask against the face of the wearer as the ambient pressure decreases.

Other objects of this invention will be readily perceived from the following description.

ited States Patent Too ments of the invention in which Fig. 1 is an elevational view, partly in section, of the compensating device of the present invention employed with a breathing mask;

Fig. 2 is a fragmentary view, similar to Fig. 1, of another form of the present invention; and

Fig. 3 is an elevational view, partly in section, of another type of compensating device.

Referring to the drawing and particularly Fig, 1, there is shown an oxygen breathing mask 10 connected to a headgear 11 such as a hard shell helmet, for example, by harness straps 12. The headgear 11 may be a soft helmet, a headset, or a net helmet, if desired. It is only necessary that the headgear be joined to the harness straps 12 to support the mask 10. The harness straps 12 are joined to the headgear 11 by a connecting mechanism 14. Oxygen is supplied to the breathing mask 10 in a wellknown manner through a conduit 15.

Disposed between the occipital area of the wearer and the interior of the helmet is a resilient or expansible member 16. The resilient member 16 is preferably made of foam rubber of the open cell type with a fabric 17 adjacent one portion thereof. The fabric 17 is secured to the foam rubber by dipping the resilient member 16 in a rubber bath to form a rubber coating 18 around the entire surface of the resilient member. This seals the air within the open cells of the foam rubber but permits ready communication between the various cells to prevent any rupture thereof. Thus, the resilient member 16 is formed with air trapped in the interior thereof. By securing the portion of the resilient member 16 having the fabric -17 secured thereto to the inside of the headgear 11, it is prevented from moving up or down, as viewed in Fig. 1; thus any expansion or contraction of the resilient member 16 must occur between the occipital area of the wearer and the headgear 11. Considering the operation of the present invention, the breathing mask 10 is connected to the headgear 11 at ground level with the tension of the harness straps'12 being sufficient to urge the mask into sealing relationship with the face of the wearer; however, the pressure of the mask on the face of the wearer is very slight. As the altitude of the aircraft increases, the ambient pressure decreases and the trapped air in the resilient member 16 expands. This causes the headgear 11 to move backwards toward the position shown by the dotted lines of Fig. 1. Since the movement of the headgear 11 in the backward direction moves the connecting mechanism 14, the tension of the harness straps 12 increases. The size of the interior of the resilient member 16 is designed so that the tension of the harness straps 12 will always be sufficient, after the mask 10 is secured against the face of the wearer at ground level sufficiently to form a seal therebetween, to maintain a seal between the mask and the face of the wearer at any altitude. When the aircraft descends in altitude, the resilient member 16 contracts since the ambient pressure increases and the headgear 11. returns toward its solid line position of Fig. 1. As the headgear 11 moves forward, the tension of the harness straps 12 reduces but is still sufficient to maintain a seal, between the mask 10 and the face of the wearer.

is made of foam rubber of the closed cell type, instead of the member 16. Otherwise, the structure is the same as Fig. -The closed cell type has air trapped in each of its cells and no rubber coating is necessary but a fabric 17 is secured to one side of the member 16. The resilient member 16 is secured to the interior of the headgear llsirnilar to the resilient member 16 by securing the portion of the member 16' having the fabric 17 secured thereto to prevent the member 16' from moving vertical-1y. This causes the expansion and contraction of the. member 16' to occur between the occipital area of the wearer and the headgear 11.

The movement of the headgear 11 of Fig. 2 is similar to that otf'Fig. 1. Thus, the tension of the harness straps 12 increases through rearward movement of the headgear 11 when the altitude increases and decreases through forward movement of the headgear 11 when the altitude decreases.

"The modification of Fig. 3 is similar to Fig. 1 in that the breathing mask is secured to the headgear 11 by the harness straps 12 through the connecting mechanism 14. Oxygen is supplied to the breathing mask 10, through the conduit 15.

The resilient member'l of. Fig. 1 is replaced in the embodiment of Fig. 3 by a hollow resilient member 19, which is preferably'for'rned of rubber. This member 19 is disposed between the occipital area of the wearer and the interior of the headgear; it is secured to the inside of the headgear to insure that its expansion and contraction occur in a horizontal direction rather than in a vertical direction. The portion of the member 19 secured to the headgear hasa fabric 17 secured thereto to prevent damageto the material of the member.

The interiorof the resilient member 19 is connected to the conduit by a conduit'ill so that a portion at the oxygen supplied through the conduit 15 to the breathing mask 10 flows into the interior ofthe resilient member 19. As the ambient pressure decreases'due to the increase in altitude, the pressure of 'the supply oxygen increases to increase the pressure within the interior of the resilient member 19 to move the headgear 11 backwards toward its dotted line position of Fig. 1. This results in the connecting mechanism 14 moving rearwardly to increase the tension of the harness straps'12. When the aircraft descends, the pressure of the supply oxygen flowing through the conduit 15 decreases; the combination of the increased ambient pressure and the decreased oxygen supply pressure within the interior of the resilient member 19 causes the resilient member 19 to contract and return the headgear 11 toward its solid line position. This, of course, reduces the tension of the harness straps 12 in the samemanner as the contraction of the resilient member-16 of" Fig. 1. The size of the resilient member 19 is selected so that the tension of the harness straps 12 is always sufiicient to maintain a seal between the mask 10 andthe face of the wearer at any altitude after a seal has been formed at ground level. The resilient member has an'area approximately the same as the area of the oxygen mask 10 to insure that the compensation of the tension of the harness straps 12 is as desired.

It will be understood that the resilient member 16, 16 or 19 may be secured to the exterior of the headgear 11, if desired. Since there would be no movement of the headgear 11, it would be necessary to secure the resilient member. to the harness straps whereby the movement of the resilient member would varythe tension of the harness straps to maintain aseal between the mask and the face or" the wearer.

"It will be understood also-that the regulation of the expansion and. contraction of the resilient member may be manual rather than automatic, if desired. For example, a'manual controlled valve could be employed inthe conduit-20 to regulate the oxygen flow therethroug'h to the interior of-the resilient member 19 whereby'the pressure within the member 19 could'be varied manually.

-Anaadvantage' of this invention is that it providesa more. comfortable fit of the mask at low altitude flying.

Another advantage of this invention is that the pilot is not required to manually adjust the tension of the mask harness as the altitude varies. A safety factor of this invention is that the automatic adjustment of the tension of the mask harness insures that there is no leakage around the mask.

For purpose of exemplification, particular embodiments-oftheinvention have been shown and described according to the best present understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to withoutdeparting from the true' spirit and scope of the invention.

I claim:

1. In combination, a headgear, a breathing mask, harness means connecting the mask to the lower front portion of said headgear, and resilient means affixed to the inside, rearwardmost portion of the headgear'and adapted to be disposed between the interior of the headgear and the occipital area of the wearer to increase of decrease automatically the tension of the harness means as 'the pressure correspondingly increases or decreases, said resilient means afiixed' to said headgear comprising an open cell foam rubber member and an impervious rubber coating enclosing said foam rubber member so that air is trapped within saidfoam rubber.

2. Incoinbination, a headgear, a breathing mask, harness means connecting the mask to the headgear, a resilient memberpositioned in fixed relation to the inside of the-headgear and adapted to be disposed betwee'nithe interior: of the headgear and the occipital area 'of the weareninlet conduit means for supplying oxygen to said breathing-mask, and means to divert to the interiorof the resilient-member a portion of the oxygen supplied to said breathing mask by said inlet conduit means whereby'the resilient member expands as the oxygen-pressure increases when the ambient pressure decreases to increase the tension of the harness means and vice versa.

3. In combination; a headgear, a breathing mask, harness means connecting the mask to the bottom-front portion of said headgear, a hollow resilient member secured interiorly to the lower portion of the headgear so that the occipital area of the wearer is contacted by said resilient member, first conduit means attached to said breathing maskand adaptable for delivering a main supply of oxygen thereto, and second conduit meanslin communication between said first conduit means and the interior of said hollow resilient member to divert to the interior of the resilient member a portion-of the oxygen delivered tothe breathing'mask whereby the resilient member expands as the oxygen pressure increases when the ambient pressure decreases to increase the tension of the harness means and vice versa.

4. A breathing mask for use with a headgear .or the like, r harness means connecting the mask to the lower front portionof said headgear, and a rmilient member affixed to "the interior rear portion of saidheadgear and adapted to; be'disposed between the interior of the headgearrandthe occipital area'of the wearer, a conduit attachcd' to and in eommum'cation with said breathing mask-and adapted to supply oxygen thereto, passage communicating means to divert to the interior of the resilient member .a portion of the oxygen supplied to the, breathing mask by way of said conduit whereby the resilintmerrib'er expands when the oxygen pressure increases as the ambient pressure decreases to increase the tension of the harness means and vice versa.

References Cited in thefile of this patent 1 UNITEDSTATES PATENTS ,354,840 Seletz Aug. 1, 194 2,461,364 Ackerman Apr. 19, 1949 1,742,039 ,Bloom Apr. 17, 195 1, 6 Quilter ot al. NOV. 25, 1,958 2,868,195 Finken Jan. 13, 1959 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,970,593 February 7, 1961 Henry W. Seeler It is hereby certified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 34, for "it" read is column 4, lines 20 and 21, for "to increase of decrease automatically" read to automatically increase or decrease "a Signed and sealed this 1st day of August 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

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