US2908272A - Gas mask breathing resistance - Google Patents

Description

2 Sheets-Sheet 1 Filed March 31, 1958 INVENTOR. Armard llMafsin ATTORNEY A. ,V. MOTSINGER GAS MASK BREATHING RESISTANCE Oct. 13, .1959

Filed Match 51, 1958 2 Sheets-Sheet 2 l/VVE/VT'OR Armard V. Mats/rigor BY A WM AT TORNE) 2,908,272 GAS MASK BREATHING RESISTANCE Armard V. Motsinger, Aberdeen, Md. Application'March 31, 1958, Serial No. 725,457

8 Claims. (Cl. 128-141) Granted under Title 35, U.S. Code (1952), sec. 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 to me of any royalty thereon.

This invention relates to a face mask, and more particularly relates to a meansfor both reducing breathing resistance and for continuous defogging of the eyelens of a face mask.

It has long been a problem in the face mask art to devise means to reduce breathing resistance in conventional masks in order that the wearer may more comfortably wear a mask for a longer time. It is well known to anyone who has ever worn a conventional gas mask that breathing is somewhat diflicult, particularly deep breathing. Upon undergoing physical activity that requires faster and deeper breathing, the presently known masks do not allow the proper flow of air to assure the comfort of the wearer. This has resulted either in a tendency to remove the mask sooner than it is deemed proper or in necessarily reduced activity. An obvious solution has been to increase the canister size and weight, but this has serious disadvantages'in that such increases would naturally impede the activities of the wearer.

A further problem, fogging of the lenses, has plagued the art, particularly in cold climates. However, substantial advances have been made in overcoming this problem by directing incoming airfrom the canister over the inside of the lenses of the face piece. While this structure has met with limited success, it has been found that frequently the lenses have fogged during exhalation particularly as temperature conditions become more severe.

The shortcoming of the old masks has been that the air used for defogging enters only during the inhaling cycle of breathing, while during exhalation no air is drawn across the lenses. It is during this latter period that fogging has been experienced, particularly due to the escape of minute amounts of exhaled breath from'about the nose piece into the area surrounding the eyelenses. Regardless what amount of air is drawn across the eyelenses, if it is not continuous, it has been found that some fogging will occur during exhalation. In prior art masks, it is not possible to have a continuous flow of air across the eyelenses.

Thus, it is an object of this invention to provide a face'mask that reduces breathing resistance.

Another object of this invention is to prevent fogging of lenses under varying climatic conditions.

Another object is to continuously defog the eyelenses throughout the breathing cycle.

Another and more specific object is to reduce the size and weight of the canister and not increase the breathing resistance of the wearer.

Another object is to produce a longer period of effectiveness for conventional canisters.

Other and more specific objects, as well as-a clear understanding of the invention, will be had upon reference to the drawing and the included detailed description.

Patented Oct. 13, 1959 'mcommunication with both'the canister and interior of the mask, will provide an additional supply of air which maybe drawn from upon inhalation to ease breathing. This surge chamber, after deflating due to inhalation, will expand due to its inherent resiliency and draw air into the mask from the canister even while the wearer is exhaling. This novel feature provides a continuous stream of air which is directed onto the eyelensesof'the mask so as to prevent fogging.

In the drawing:

Fig. 1 is a view of the complete mask assembly.

Fig. 2 is an enlarged sectional View of mask showing Figs. 3, 5 and 7 are sectionalviews of modified forms of surge chambers.

Figsq4, 6 and 8 are perspective views of the modifications of Figsj3, 5 and 7, respectively.

Referring to'the drawing, 10 indicates a facepiece, having a faceblank 11 with the usual harness assembly (not shown), while generally at 12 is shown a conventional eye piece consisting of eyelenses 14 and 15, and eyerings 16 and 17. While I have shown two lenses, it will be understood that a single lens extending the width of the facepiece may be employed. Inside the mask is the usual nose cup'18 and nose cup oneway inlet valves 20 and 21 respectively, the nose cup being designed to fit securely around the nose of the wearer to control the entry and exit of air in a well known manner. At 22 is shown a conventional outlet valve comprising the usual cover, disk and seat (the latter two not shown). To purify theincoming air a canister 24, which is of conventional design having a particulate filter and gas absorbant material, is secured to the canister mounting piece 26. A flexible disk 28 functioning as a one way valve is secured to the underside of the canister mounting piece 26 by a snap fastener 30. All the foregoing structure is not asserted to be novel, but rather is a part of well known masks used in recent years.

The canister mounting piece 26 is secured to the outside wall 32 of the face blank. This wall forms with inside wall 34 a canister air pocket 36 which extends only over approximately one-half of the front portion of the face blank and is in air communication with the canister. Directly under the eyelens 14 is the sole outlet 38 for the canister air pocket providing communication between the canister and the interior of the face blank 11. On the opposite side from the canister is a substantial duplicate of the double walled canister air pocket forming the surge chamber air pocket 46 with its outer and inner walls 42 and 44 and an outlet 48 providing communication between the surgechamber and the interior ofthe face blank. The two pockets 36 and 46 are not in fluid communication except through their respective outlets 38 and 48. The outlet 48 in the surge chamber air pocket is similarly situated in relation to lens 15 as outlet 38 is to lens 14. Secured to the outer wall 42 is a tube 50 providing air communication between the surge chamber 52 and the pocket 46, the tube 50 and the surge chamber being connected by a ferrule 54 in a conventional manner. The surge chamber 52 may be made of any flexible, elastic air tight material such as rubber or synthetic plastic with a resiliency sufficient to deflate upon inhalation and to expand to its normal size after inhalation. The configuration is not critical, but for convenience and ease of wearing, the shape of the preferred embodiment is in the form of sections as shown, each in communication with the other. The surge chamber may be made with a uniform resiliency throughout its length, or as a modification, it may be made less yielding in certain portions which may be accomplished, for example, by using a greater thickness of material at the less resilient portions. The purpose of this modification is to provide a reserve volume to be used only upon the deepest breathing while during normal breathing only the more resilient portions are operating, or also to insure an equal deflation in all sections at the same time. A snap fastener 56 is provided to secure the end of the surge chamber around the neck of the wearer onto the other side of the mask. The surge chamber thereby also functions as a neck strap to more securely hold the face piece to the face.

In operation, the fresh air flows during inhalation, as indicated by the solid arrows, through the canister into the canister air pocket 36 through the outlet 38 onto the lens 14 and then into one or both of the nose cup valves. At the same time, air is drawn from the surge chamber 52 into pocket 46 and then through outlet 48 onto lens 15 and also into one or both of the nose cup valves. Air is thus directed onto both lenses and into the eyelens compartment formed by the nose cup, the eyelens, the facepiece and the wearer from which it is breathed by the wearer through the one way nose cup valves 20 and 21. This novel feature of using a surge chamber has resulted in a reduction in breathing resistance as shown by the following test made with a conventional breathing machine having a pulsating flow simulating actual breathing, a surge chamber of 430 ml. capacity and a standard US. Army M11 activated charcoal type canister having continuous flow resistance of 68 mm. H O at 85 l./m. Normal breathing is at the rate of about -15 l./m.

Effect of surge chamber of breathing resistance Pulsating to simulate actual breathing.

It is clear that a larger surge chamber would provide an even greater reduction in breathing resistance, especially at higher breathing rates due to increased work loads.

Upon exhalation, the novel features of this'invention are further in evidence. In conventional masks, air is not continuously drawn across the lenses whereby fogging usually occurs during exhalation. But as is clearly shown in Fig. 2, the dotted lines indicate that there is a flow of fresh air during the exhaling cycle of breathing and that it is drawn into the canister through the eyelens compartment and across the lenses 1-4 and into the deflated (by inhalation) surge chamber to expand the same. The surge chamber acts automatically in this operation to defog the lenses during exhalation or after inhalation without any assistance from the wearer except his breathing. Further, it should be evident that there is a continuous flow of air into the mask which is continuously directed onto the lenses for defogging in a manner wholly different than heretofore known in the prior art.

A further advantage of this continuous flow of air through the canister is that for a given depth of absorbent in a canistcrto which canister weight is proportional the canister is capable of performingsatisfactorily for a greater total volume of air or effective gas protection life when there. is a continuous flow than when there is a strong pulsating air flow. The reason for this is a simple one, the faster the air flows the less efficient the absorbent, and thus for fast pulsating flowing air which is necessary to obtain the required volume per unit time, a deeper and therefore a heavier canister is required. It

also should be noted that if the same total volume of air per unit time were required by the wearer, the canister size necessary would be able to be reduced if there were continuous flow than if there were a pulsating flow.

The position of the surge chamber and its outlet 48 in relation to the canister is preferably such as shown in the drawing. Thisrelationship permits air to be drawn across the lenses for defogging during exhalation, whereas if the surge chamber and outlet were between the canister and the mask there would be no such function during exhalation. In the latter position, the instant surge chamber would act to reduce resistance, but not reduce fogging and thus would not perform the functions of the invention.

While there has been described above one complete embodiment of the mask employing one particular form of surge chamber, there are various other designs that are usable and which may be preferred in some instances. Thus, in Figs. 3-6 are shown two types of surge chambers that need not be made of resilient material but rely upon springs for operation. The modification of Figs. 3 and 4 is a bellows formed of two rigid plates 60, 62 of light metal plastic or the like joined by hinge 64 and an accordion-pleated bag 66 which may be made of any suitable impermeable material. Plate 60 carries an inlet tube 68, which is secured to the tube 50 of the mask at the same point as the surge chamber 52 as shown clearly in Figs. 1 and 2. Plate 60 may lie directly against the facepiece of the mask. Within the chamber formed by plates 60 and 62 is a bifurcated spring 70 which seats on ledges 72 of plates 60, 62. This spring tends to force plates 60, 62 apart and will be of a strength such that it will compress and expand according to the breathing cycle. Bag 66 need not be elastic in this case.

Another alternate type of bellows making use of a spring is shown in Figs. 5 and 6. This embodiment comprises a flexible spirally pleated bag 74' which surrounds a suitable spiral spring 76. The bag is provided with an inlet tube 78. Again, the spring tends to expand the bellows but is compressed upon inhalation.

The chambers of Figs. 3-6 have certain advantages over that of Figs. 1 and 2. Since these embodiments use springs, which can be more accurately designed than rubber chambers, their expansive action can be more readily controlled. Further, as they are supported on the side of the face piece opposite the conister, they provide a balancing of the weight on the face piece. Moreover, the elasticity of the springs does not change on storage as does that of rubber. On the other hand, they are more complicated in structure and, due to their position, may provide more interference in the use of a weapon or instrument.

A further embodiment of the chamber is shown in Figs. 7 and 8. Like the modification of Figs. 1 and 2, it is made of resilient rubber and passes around the back of the wearers neck. It is, however, different in form, comprising a plurality of longitudinal pleats which expand radially. This form oifers somewhat less resistance to air flow at high breathing rates than the modifications of Figs. 1 and 2, and for a given resiliency can be made of somewhat heavier and therefore sturdier material.

From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present invention that come within the province of those skilled in the art; however, it is intended that all such variations in structure, modes of usage and materials be considered to be within the scope of this invention as limited solely by the appended claims.

I claim:

1. A gas mask comprising a facepiece, having an outside wall, an air inlet means on said outside wall on a first side of said facepiece, at least one transparent lens member on said facepiece, an air outlet means mounted jacent a lens member, a second air pocket and an outlet for said second air pocket adjacent a lens member, and an expansible surge chamber in open communication with said second air pocket, whereby when the wearer inhales, air will be drawn through said air inlet means and from said surge chamber across a lens member and into said nosecup, while when the wearer exhales said surge chamber will expand and draw air through said air inlet across a lens and into said surge chamber.

2. The structure of claim 1 wherein the surge chamber is flexible and elastic.

3. The structure of claim 1 wherein the surge chamber is expanded by biasing means.

4. The structure of claim 1 wherein the surge chamber is hinged at one end and expandable at an opposite end by a bifurcated spring.

5. The structure of claim 3 wherein the surge chamber is expanded by a coil spring.

6. The structure of claim 1 wherein the surge chamber is pleated elastic and radially expandable.

7. The structure of claim 1 wherein the surge chamber is elongated and constructed of a more resilient material at one portionof its length than at a second portion of its length whereby the expansion of the surge chamber is controlled throughout its length.

8. A device as defined in claim 1 wherein said surge chamber is elongated and resilient, said chamber having an open end connected to said second air pocket and being closed at its other end, cooperating detachable fasteners on said facepiece and on the closed end of said surge chamber, the fastener on the facepiece being positioned on the side opposite said second air pocket, and the surge chamber being sufliciently long to fit around the back of the wearers neck.

References Cited in the file of this patent UNITED STATES PATENTS 2,077,054 OLeary Apr. 19, 1937 2,365,779 Schwab Dec. 26, 1944 2,810,386 Reed Oct. 22, 1957

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