US 3029812 A
Description (OCR text may contain errors)
April 17, 1962 J. N. MATHEsoN RESPIRATOR Filed March s, 1958 2 Sheets-Sheet 1 INVENTOR. :fb/Wes Norma/z /azeson ATTORNEYS.
RESPIRATOR ZSheets-Sheet 2 Filed March 3, 1958 .o E V. WM M M W o s m a 6 f O O O O O O O O O O O O o o o o O O O O Bxl/@www ATTORNEYS ttes This invention relates to a respirator.
Respirators, as they have been produced for the market, are of widely varying forms. In many instances they include a covering for the nose and mouth and then have air pickup devices built on to this covering and protruding outwardly therefrom, each in an appropriate shape and formation to include some filter medium. A large part of the surface area of the mask which covers the mouth and nose is not utilized for any filtering function. Further, the mask which covers the mouth and nose is frequently formed of rubber and this material together with the built on filter material housing provides a sizable weight to be worn on the face. Many of these respirators also utilize some metallic parts such as springs or buckles or clasps which become tarnished or corroded and fail to function properly. Further, many of these respirators are formed of a relatively large number of parts requiring considerable assembly operations to provide the finished article. Also there is provided an inhalation valve and exhalation valves which are not too eilicient in their prime function of operating with a minimum of negative and positive opening pressure, particularly when the seating surfaces become wet with condensation. In addition, many feature inhalation valves which, while essential to other design, are objectionable in function for the wearer, hence they are removed and as a result, the performance efiiciency of these respirators is impaired.
This invention has to do generally with removing the undesirable features above mentioned and providing further improvements.
More specifically an object of the invention is to utilize the general shape of the mask over the face for supporting the filter medium housing, thus utilizing a heretofore unused area to good advantage to obtain filter area within the minimum forward projection, thereby providing the wearer the maximum field of vision and compactness of design.
Another object of the invention is to provide a large surface area of the filter medium through which the air to be in haled may be drawn and thus spreading over a large area the contaminant which is to be collected on the filter and thus increasing the life of the filter by this extended area, the same being less easily clogged as the contaminant accumulation is less concentrated per unit area.
Another ob'ect of the invention is to provide a filter medium which may be easily removed and replaced in a simple and positive manner.
Another object of the invention is to provide the device in two parts with a filter medium held between the two parts and the two parts interlocked by interiitting parts so that they may bc easily detached or put together for the holding of the filter medium between them.
Another object of the invention is to provide a respirator having a relatively resilient material to engage the face of the user and by reason of its resilience together with its anatomically contoured facial contact can be exurally drawn into engagement with the face, thereby sealing itself against the face to prevent the passage of air between the edges of the respirator and the face.
A further object of the invention is to provide the cover of the respirator relatively stiffer than the base which engages the face so as to structurally align the mask body aten Patented Apr. 17, 1962 to assist in retention of the filter medium, while maintaining structural conformity of the facial contact to insure a proper fit.
Another object of the invention is to so space the filter medium from the body and from its cover that substantially the entire surface area of the filter medium will be exposed and available for the passage of air therethrough.
Another object of the invention is to hold the filter medium such as a piece of felt at its marginal edges the saine being supported at a few spaced points on its under or downflow side affording the large surface of the filter medium for the passage of air therethrough.
Another object of the invention is to provide a construction, the parts of which may be injection molded.
Another object of the invention is to use a lightweight material which will have the desired function of being sufiiciently resilient to fit the face or may be stifened as desired by changing its composition or by providing ribs where necessary in the parts to secure the desired sh ping of these parts.
Another object of the invention is to provide a'device which will have no metal in it which may corrode due to the weather or contaminant encountered.
Another object of the invention is to provide a respirator which will be light in Weight and thus one which will not be tiresome to wear on the face.
Another object of the invention is to provide a device which will be extremely simple in construction and thus one which may be easily assembled with a minimum of effort.
Another object of the invention is to provide a device in which the need for an inhalation valve is eliminated through inclusion of a baffled air inlet in combination with the unified function of the exhalation valve and filter medium whereby the functional efficiency of the respirator is greatly improved.
Another object of the invention is to provide a respirator, the basic body portionof which will remain the same but into which there may be positioned different filter media for different purposes, thus making the respirator adaptable for many uses by the selection of the desired filter medium without any change in the basic body portion of the device.
With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.
In the accompanying drawings:
FIGURE l is a side elevation of the respirator;
FIGURE 2 is a section of line 2 2 of FIGURE 1;
FIGURE 3 is a central longitudinal view on line 3-3 of FIG. 2;
FIGURE 4 is a section on line 4--4 of FIGURE l;
FIGURE 5 is a section on line 5--5 of FIGURE 1 with the filter medium omitted; y
FIGURE 6 is a fragmental view illustrating the band for securing the respirator on the face and the means for securing the band to the respirator;
FIGURE 7 is a` sectional view of a modified form of filter and cover;
FIGURE 8 is an elevation view partly broken away and in section of the structure shown in FIGURE 7;
FIGURE 9 is a sectional view similar to FIGURE 7 but of a still different modified form;
FIGURE 10 is a fragmental section view of a still further modification;
FIGURE ll is a sectional view of a fragmental part of the respirator showing a modification; and
FIGURE l2 is a view similar to FIGURE l1 of a different modification.
The body portion 10 of the device although somewhat aoaasia 3 irregular in contour, as may be seen, because of the necessity for it to tit the face has a lower portion of its rear edge 1I (FIGURES l and 3) of a shape and length to extend along the area of the face just below the mouth While the side l2, extending upwardly therefrom, tlares outwardly slightly and is on a curvature to ht along the cheeks of the user at either side of the nose while the upper portion 13 (see side elevation FIGURE l) is arched at 14 (FIGURE 2) to fit over the nose, these edges being all very flexible so that they may be flexed against the face by an elastic band 15 and between the resilience of the material of the mask and the softness of the face they will provide an airtight seal along these encircling portions of Contact.
From these flange portions just mentioned, the body arches forwardly as seen generally at 16 (see also FIG- URE 4) and along this arched portion there is a recess or set back area 17 which also conforms to the general curvature of the remainder of the body but is of a size to receive the lilter medium which, for example, may be a piece of felt cut out substantially the shape of set back area 17.
Bordering this recess 17 there is molded into the body a groove 18 which extends completely about the perimeter of the recess encircling the same and providing an overhanging lip 19 which serves a retaining function. The lter 2G is positioned in this recess and is of a thickness to partly fill the groove. The filter, however, is of a fluy nature and easily compressible and is compressed and held in place by a cover 21 having a thin llanged edge 22 to extend into the groove and compress the ilter material which is to seal the edge against passage of air. In order for there to be a better support, the wall 23 of the groove is of a greater height than the lip 19 as will be seen from the drawing.
It is desired that the filter be spaced from the Wall of the recess I7, which I accomplish by providing a center rib 24 and side ribs 24a and 24h along the bottom of the recess standing outwardly therefrom and ribs 25 extending outwardly from the wall of the recess on the upper edge thereof, while there may be a plurality of projections 26 along the middle portion of the recess thus preventing the filter from laying against the wall 17 of the recess and interfering with the free passage of air therethrough.
Openings 27 are provided between the vertical wall 17 of the recess and the horizontal wall 28 of the lower face part of the mask so that there may be a passage of the air downwardly vertically as shown by the arrows from the inner surface of the filter into the area 29 of the mask. These openings 27 are open at all times and unobstructed providing an indirect or baffled airflow. This arrangement of airflow in conjunction with an exhalation valve which opens at low pressure avoids the necessity of an inhalation valve. This is accomplished thru the pressure drop differential between the exhalation valve and iilter medium, whereby the positive pressure of exhalation causes the valve to open for full release of expired air while the higher pressure drop across the lter together with the downward deflection of the exhalation prevents its re-entry into the influent lter chamber.
The cover 21 as may be seen in FIGURE 4 is curved so as to conform generally to the shape of the wall 17 of the recess and it is provided with a plurality of louvers or portions 32a, b, c, d and e with openings 33 between these louvers for the passage of air to the outer surface of the filter 2t). These louvers being of arcuate form need only be supported at their arcuate ends and at one or two points intermediate the ends which comprises a strip 3), 31 of material on each side joining the louvers 32a, b, c, d and e at their center portion by extending across the space 33. This post or support may take any shape or form desired but I have illustrated them as in a W-shape with a V on each side of the center. The edges 22y of this cover 21 may be tucked into the recess 18 and when its entire periphery is positioned its arcuate form will space it from the filter (see FIGURE 4, space 34) thus providing free access of air to the outer surface of the filter. By reason of the louver formation, any heavy dust which is settling will be deflected downwardly rather than pass upwardly through the openings 33 as inhalation proceeds, thereby extending the service life of the filter by reducing dust accumulation.
The bottom wall 2d which forms the lower portion of the mask serves to direct the inhalation air entering through openings 27 upwardly from the arca 29 of the mask. In this wall 28, however, a neck 35 extends downwardly and on this neck l provide an exhalation valve 36 which will telescope over the neck 3S and be held in position either by its own inherent contraction on the neck or by means of a rubber band 37 seated in a groove herein as may be seen.
In some cases instead of having a neck 35 of the same piece of material as the bottom wall 23, I may provide an opening 28 in the bottom wall as shown in FIGURE l1 and insert a separate neck 35 having an annular groove 351 to receive the bottom wall and a second annular groove 55.?, to receive an annular part 36' of the valve 36 for holding it in position.
In another instance the neck 353, FIGURE l2, may have a rib 354 thereon to hold a ring 355 which affords a shoulder for holding the annular part 36 of the valve 36.
The body or base of the mask is provided with strap securing means 4S which is molded with the body and suitably milled to provide bars 41 and 42 and I secure the strap I5 in between the two bars 41 and 42 by passing the strap from the forward side completely through the two bars then back over the rear bar 42 and beneath the front bar 41 (sce FIGURE 6). By reversing the pull or" the headband about the two bars, the facial contact of the mask is flexed inwardly as seen in dotted lines in FIGURE 6 against the cheek and nasal area of the face so as to form a positive seal with minimum contact pressure, thus I am able to gain an improved seal without the need for a separate stiifening member. By this arrangement of two molded bars, it is unnecessary to use any metal parts either for securing the strap together or securing the strap onto the mask. Thus I have provided a mask which has no metal in it whatsoever even in the securing strap. This also provides for simplicity in construction and avoids metal parts which will corrode.
In some cases instead of utilizing a piece of felt as a filter medium, I may wish to provide a medium which will take out other things than dust and provide a paper as shown in FIGURE 7 which will be sufficiently stiff to have a preformed shape and will be corrugated as shown at 50 sealed by paper end pieces 51, 52 (FIGURE 8) and in this instance the cover 53 which I provide will of necessity be somewhat deeper than that utilized for the felt medium but the cover will be so shaped that its iianges 5ft may be snapped into the groove 18 the same as heretofore. The cover is perforated as at 55. The end seals 51, 52 are flanged to extend into groove 18 and thereby sealed by gasket 56.
In a still dierent situation I may wish to provide a filter for gas or chemicals in which there will have to be a medium having some depth. This may be formed as a cartridge 6() having a perforated wall 61 and a flange 62. The same covers 53 and gasket S6, as heretofore provided, may be sealed in groove 18. The cover 53 is spaced from the wall 61 and is perforated also for the passage of air into the space 65 and from thence through cartridge 60 and then downwardly through passage 66 and through openings 27 as above pointed out.
In FIGURE 10 the cartridge 70 has walls 71 and 72 both perforated as at 73 and both llanged as at 74, 75
which extend into groove 18 and are sealed therein byv gasket 76 and in this case no cover will be used. The cartridge will contain finely divided material as seen in FIGURES 9 and 10 and may be changedwith a similar cartridge as desired.
In -molding this two part mask or respirator I will utilize a thermoplastic material of two different characters, one for the base and the other for the cover. The base or mask will be of a high pressure low density material so as to be resilient and flexible in the areas which engage the face while the cover will be of a low pressure high density material to maintain the general structural shape of the more resilient mask body within the contines of the form desired and will also serve to space itself from the filter and provide a shaping front for the filter. 'In this way I may utilize a lightweight material and yet provide a respirator having both flexible and stiff characteristics as desired in the two parts which are utilized.
1. A respirator comprising a body to cover the nose and mouth portions of the face and seal at its periphery with the face, said body being of generally U-shape in horizontal cross-section with the curvature of the U being about a vertical axis, a cover over a portion of said body, said cover having top and bottom peripheral edges and having a wall with a similar U-shape in horizontal crosssection at its top, bottom and mid portions also with the curvature of the U about a similar vertical axis, vertically extending lips on said body overlying said top and bottom peripheral edges of said cover to hold the cover in place against movement outwardly radial of the curvature of said body, a lter between said cover and body, said cover and body having openings for the passage of air.
2. A respirator as in claim l wherein the cover is spaced from the tlter.
3. A respirator as in claim 1 wherein the body is recessed from the iilter in an area covered by the filter to space the lter therefrom.
4. In a respirator a body part provided with a generally upright wall to cover the nose and mouth portions of the face and seal at its periphery with the face, a portion of this upright wall being inwardly recessed, a bottom wall spaced from the recessed portion of said upright wall to provide a passage between said bottom wall and the lower recessed portion of the upright wall, a filter spaced p from the recessed portion of said upright wall extending over the same and exposed to the air and an exhalation valve in said bottom wall opening at a pressure less than needed to pass air through the filter whereby air may be drawn in through the filter, pass beneath said recessedv portion of the upright wall and be exhausted through said valve.
5. In a respirator, a body having bottom and side walls to cover the nose and mouth portions of the face and seal at its periphery with the face and provided with openings in the side walls at all times unobstructed, an imperforate -baiile carried by the body inwardly of the side wall area which is provided with said openings and spaced at its lower edge from said bottom Wall to provide a passageway to .the interior of the body, a lilter between the side wall area provided with said openings and said baille and spaced from the baille and sealed to the body, an exhalation valve in a wall of said body inwardly of said filter and free from interference with said lter, said exhalation valve and filter being so relatedwith respect to their ability to pass air that the exhalation valve will provide Yless obstruction to exhalation than will said lter whereby an inhalation valve is unnecessary.
p References Cited in the tile of this patent UNITED STATES PATENTS