CA1269587A - Valve assembly for a respirator - Google Patents

Abstract

ABSTRACT

A respirator having a disposable filter includes a valve body having central aperture providing concentric inhalation and exhalation valves.

Description

1BLY ~OB
~ PLACle~BLl~ PIRATt)3 lField 0~ ~vent~o~
This invention relates to respirators- of the type usually known as dust ma~ks, such respirators including a ~ilter of fiberous material for trapping and hold~ng particulate matter in the ~orm of dust or fume, or &erosols in the form of mist suspended in air that passes through the filter.

B~ckgro~d o~ the b~ tioD `
In their simplest form, such respirators are comprised of a face piece formed from stQ~ilized textile fibers, and which hRs been appropriately molded or otherwise formed for it to extend over the nose and mouth of a user, and, which is held in that position by elastic straps attnched to the face piece and whi~h are passed over the user's head to resilienUy hold the respirator in situ over the user's nose an~ mouth.
~ uch dust masks ~re entirely temporary &nd fuLly disposable, in that once the filtering capability of the filter has been exhausted due to clogging of the filter, the user has no option othet than to discar~ the dust mask and replace it with anotherl unused mask.
Refinements of such dust masks are disclosed in U.S. ~,319,561 Maggidson, U .S. 4,384,577, Huber, et al., and in U.S. 4,454,881, Huber, et al., each of which teaches stabili~tion and rein~orcement of the filter in order to prevenlt ~ollap~e of the face piece under the partial vacuum produced by the user during inhalation, or, accidentally by the applic~tion of manual force oi mishandling of the respirator.

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While these constructions had an elegance absent ~rom more mundane constructions, they stlll suffer from the same di~advantage that the entire respir~tor must be discarded after a relatively short period of use.
Further, in addition toimpedinginhal~tion by the u~erasparti~ate matter builds up in the filter, such masks also progressively impede exhalation by the user through the clogged filter rnateri~l, unless some form of exh~a~on valve is provided, as t~ght in U.S. 4,4S4,881, ~uber et al. In the absence of ~n exhalation valve, a further physical stress is imposed on the user, particularly in the event that the user is involved in manually strenous work. Further, such respirators or dust masks have relatively large internal volume that becomes ~illed with exhaled air as the user exhales, and which i~ then reinhaled when the user next inhales. Heat from the inhaled ~ir raises tempe~ature of the thick (extra thick in case of metal fume) filSer fibers from exhalation. This heat is then transferred to the incoming air upon inhal~tion. A raise in temperature as low as 2 - 3 causes great psychological and phy~ic~l discomfort to the user.
An ~lternahve approach to such respirators is disclosed in U.S.
Des, 270,957, Maryyanek, which proYides a face piece o~ soft rubber-like material, to which is attached a replaceable air filter in the form of a cartridge that snaps onto an inlet of the ~ace piece controlled by a conYention~l inlet valve. The face piece i~ separately provided with dual conventional exhalation valves atta~hed to the face piece at positions spaced from the inlet valve7 and~ which are actuated ~y the rise in pressure in the ace piece upon exhalation by the user.

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In this construction, air inhaled through the ~ilter does not have to be subsequently exhaled through the iilter, but instead, is by-passed through the exhalation valYes.
While this construction is successful in retaining disposability and replacement of the Iilter cartridge, it carlies with it the disadvantage that the entire filter cartridge must be disposed OI after UlSe, with the attendant expense thereof, and also carries with it the disadvantage of the respirator being of considerable bulk and weight, and thus of perceptible inertia to movem~nt of the user's head; Also, in this construction, the face piece and its associated exhalation valves present a relatively large internal volume within the ~ace piece in which exhaled air is trapped, and, subsequently is re-inhaled by the user.
Replacement ~ilter respirators of this latter type are referred to as semidisposable respirators, in that the cartridge incorporating the filter material ean be removed from the fa~e piece for disposal and replacement by an unused cartridge, the face piece itself and its ~ssociAted inhalation and exhalation valves being a permanently retained pc~rtion of the respirator.

Summary of the hlvention It is an object of this invention to retain to the greatest possiMe extent the advantages of lightness, minimal inertia, snd enhan~ed area of filtration surfaces such are iound in known ~ly disposable respirators, while eliminating the di~advantages thereof, and, to retain the advantages of the known replaceable filter respirators in replaceability of the filter, while minimizing the weight penalty, kinetic iner tia, Rnd exhaled air retention dLsadYantages thereof to the greatest possi~le extent.

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This is accomplished according to the present invention by~lpro~idin a respirator that is totally devoid of separate e~halation valves and the accompanylr~ weight and inertial penalties thereof, and by incorporating ~n exhalation valve directly into a valve body providing the inlet v~lve~
The replaceable filter element is supported by a frame, which is intentionally configured for it to be extremely light in weight, and for it to be kinetically bal~ced relative to the usPr's head, and whi~h ~urther is arranged to support a fully disposable filter of considerably greater filtering area than that of a conYentional semi~isposable respirator.
In order to provide for the enhancement in effective are~ of filtering surface, and to provide for kinetic balancing of the filter frame, the frame is formed as an elong~te member of dihedral planform that wraps around the face piece and extends to opposite sides of the user's face.
Preferably the exhalation valve is positioned centrally of the frame and concentric with the inhalation valve, the Irame having ribs that support the filter material spaced from a b~ck wall of the frame, and which provide channels for directing filtered air into the face pie~e through the inlet Yalve.
In this manner, by appropriate sele~tion o~ the material employed for forming the face piece and the frame, the entire weight of the assembly can be kept to ~ fraction of that of a conventional replaceable filter respirator, and to ~ weight that only slightly exceeds the weight of a conventional fully disposable respirator.
By reducing the weight and inertia OI the respir~tor to the greatest possible extent, sources of AnnOyanCe to the user are removed, making the respirator comfortable to wear over extended periods o~ time, even in the event that the user is highly physically active.

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Further9 as the requirement for separate conventional exhalation valYes is eliminated in its entirety, the contained volume of the face piece can be reduc2d to a mere fraction of that of a eonventional semi~ispo6able respirator, thus substantially reducing the entrapment of stale exh~ed air within the face piece.
Further, by virtue of elimination of the conventional exhalation YalVeS of the conventional replaceable filter respiraltor7 the filter can be positioned in closer proximity to the user's face, thus considerably improving the field of view of the user, while at the same time further minimizing inertial effects on the user's face c~used by the respirator.
A primary use of the respirator of the present invention is in conjunction with a welders ~shield, the respirator being of sufficiently minor dimensions for it to be positioned within the welders shield without in any way affeeting or interfOEing with raising and lowering of the shield.

De~ti~n o~ the D~a~
The invelltion lNill now be described with re~erence to the accompanying drawings, which illustrate a preferred embodiment of the respirator o~ the present invention, and, in whicho ~igure 1 is a front perspective view of the removable i~lter respirator according to the present invention;

Figure 2 is an e~ploded perspective view oi~ the respirator of Figure 1;

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~igure 3 is a re~r perspective view o~ the respirator of Figure l;

~igure 4 is a cross-section through t~e respirator -taken in a horizontal plane; and ~igure S illustrQtes in cross-section an alternative embodimeslt o~ the respirator incorporating a ully disposable Silter sub-assembly.

Deæripti~ o~ the Preferred lgmbodiments ~ eferring ~igures 1 to 4 of the accompanying drawings, the replaceQble filter respirator LS indicated generally at 10, the respirator being comprised OI a ~ace piece 12, to which is attached a frame 14, the i~rame providing attachments for straps 16 employed to se2ure the respirat~r on the he~d of a user with the face piece surrounding the nose and mouth o~ the user and providing an effective continuous seal with tlle user's face, despite variations in the contours and configurations OI the particular user's face.
The face piece 12, such as is well known in the art, is molded or otherwise formed ~rom an extremely soft ~d pliable rubber-like material, that can be worn on the user's face for extended~ periods OI time without causing discomIort to the user. Optionally, the face piece 12 may be formed ~rom a foamed, closed~ell plastics m~terial, further to minimize the already minimal weight of the face piece.

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The frame, indicated generfllly at 14, is attached to ~ forw~rd portion of the face piece 12, the face piece conveniently induding buttresses 18 to stabilize the frame 14, and equ~lize the compre3sive stresses exerted on the face piece by the frame 14 at the time the frame 14 is drawn towards the user's head by the straps 16. The buttresses 18 are of particular utility in preventing inw~rd collapse of the face piece 12 at any particular location when under compressive loading and, a concomitant discontinuity in the seal between the face of the user and the face piece due to such unequfll stressing.
The frame 14 may be formed in any convenient manner and of any convenient material, including light-weight metal, but is preferably formed by injection molding fl light-weight relatively rigid, and relatively impact resistant plastics m~teri~l, such as an acrylic resin.
While the frame 14 preferably is ~ormed ~s a unitary injection molding, it can be formed with equ~l facility of separate members assembled to ea~h other.
The frame 14 is comprised by ~n outer perimetral ~lange 20 of a generally trapezoidal form, the flange 20 being symmetric~l ~bout ~ central ring 22, that is rigidly interconnected with the flange 20 by ribs 24 providing Air flow chflnnels between adjacent pQirS of ribs.
The ring 22 provides a support, or itself comprises a support for all exhalation valve 26 supported on a spider 28, and an inhalation valve 34, as is l~ter described. Optionally, the exhalation valve 26 ~nd its supporting spider 28 can be formed QS a separate sub-assembly that is a press fit within the central ring 22.

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The re~r face OI the rame 14 is completely closed off by a back wall 30, either formed integrally with the ~rame 14, or, secured to the frame 14 after the formation thereof.
The back wall 30 proYides a central opening 32 ~oncentrid with the support ring 22, such that air flowing in the channe~s provided by the outer perimetrial flange 2D, the ribs 24, &nd the back w~ll will flow towards and through the central opening 32.
The back wall 30 provides ~ relatively rigid connection for the face piece 12 in ~urrounding relationship with the central opening 32, the central ring 22 providing a support for an ann~ar inhalation valve 34.
The outer perimetrial nange 20 of the frame 14 is provided with ~ rebate for the reception of locking tongues or ribs 38 formed on a perimetrial ~lange 40 of periorate a filter retainer member 42, adapted to embrac~ and hold Q repla~eable filter member 44 in abutting relationship with the outer perimetrial nange 20, the ribs 84, and the central ring 22 of the fr~me 14.
The filter retainer member 42 is sllfficiently perfor~te to provide minimal impedence to air flow through the filter member 44, and includes a central annulus 46 adapted to eng~ge the perimeter of a circular opening 48 in the filter member 44 and hold it clamped against the centrsl ring 2 Conveniently, the filter retainer member 42 is provided with a de~iector guard 50 overlying the central annulus 4~6 for dene~ting exhaled air downwardly away from the eyes of the user, and ~way from the back side of the welders ~hield3 ii used, to prevent fogging of the lens.
:~ Preierably, the locking tongues 38 are ~symetrically positioned rel~tive to the frame 12 and the filter retainer member 42, such that the ' frame 12 will only accept the filter retainer member i~ the correct orientation in which the de~ector guard 50 has its outllet facinl downwardly.
As will be seen in the drawing~, the frame 14 is formed as a dihedral and considerably elongate in horizontal dim ensions in order that the side portions of the frame 14, can extend toward~ the user's face, and to opposite sides of the face piece la.
The assembly is completed by the straps 16, which are attached to the frame 14 by bucldes 52, either integrally formled with the frame 14 or subsequently attached thereto in any convenient matter.
Referring more particularly now to Figure 4, the face piece 12 is attached to the frame 14 by it being trapped within Q groove 54 provided by the back wall 30.
The groove 54 is of relatively large peripheral extent, such that a considerable reduction in the weight of the face piece er~ues, again resulting in minimal weight of the respirator Secured within the central ring 22, and po~itione~ on the outer side of the spider 28, is the exhalation valve 26 which is OI an e2~tremely flexible but dimension~lly stable sheet material and, which seats at its edges on a valve seat provided by the eentral ring 22 in the event that air is inhaled through the central ring 22, and, which will treely flex away from the spider 28 and the central ring 22 in the event that air is exhaled through the central ring 22, thus providing an exhalation valve integral with and positioned interiorly.of the centrsl ring 22.
Exteriorly of the central ring a2, and secllred thereto in any convenient manner, such as by ultrsffonic upsetting of the material of the central ring 22, is the inhalation valve 34, which also i3 of said extremely . ..

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flexible and dimensionally stable sheet material and which extends radially from the outer circumference of the central ring 22 and into æ~ting relationship with a valve seat provided by the ba¢k wa]ll 30 of the frame 14.
The two valves 26 and 36 complete the as.~embl~ge, the nianner OI operation of the a~semblage now being discussed.
With a filter member 44 correctly positioned on the frame 14, and held in that position by snapping the ~ilter retaining member 40 over the peripheral edges of the frame 14, the only route f~r air inhaled through the ~ilter 44 is through the ehannels provided between the ribs 24, and which lead to the central opening 32. Upon inhalation by the user, and a drop in pressure within the iace pie¢e, the flap valve 58 lifts ~t its edges, permitting ready access of the filtered air to the interior of the face piece 12 with minimal impedence, the impedence to such air ~low being greatly minimized by the extremely large effective ~rea o~ the filter 44, and the negligible impedence to air nOw through the centrsl opening 22 ~nd the inhalation vslve 58.
Upon e~halation by the user and a rise in pressure within the face piece 12, the inhalation valve 58 immediately closes, and, the exhalation valve 56 immediately opens, permitting the exhAust of exhaled a~r directly to atmosphere from the interior of the face piece la and with an absolute minimum of impedence.
Thus, e2dlaled air can not proceed into tpe channe~s between the ribs 24 and into the filter, the channels remaining charged with pure and unadulterated air during exhal~tion by the user.
Further, by virtue of minimization of the contained volume ~ the face piece 12, only a minor amount o~ exhaled air remains trapped within 1. ' `

~95~7 \j the face piece 12 ~fter exhalation by the user~ Further, and by virtue of the extremely large effecti~/e area of the filter 44, impedence to ~ir inspired through the filter 44 is minimized, even when in a partially used and partially clogged condition, thus prolonging the intervals between replacement of the filter rnaterial.
The filter material itself can be replaced with great faeility, merely by snapping off the filter retainer member 42J removal of the used filter member 44 and discarding it, repo~itioning a replac~ment filter member ~4 over the central cl~mping ring 22, and by then snapping on the filter retainer member 42, to hold the filter member appropriately clamped onto the frame 14, the ribs 24, and the central clamping ring 2i, thus inhibiting leakage of contaminated air at the peripheral edges of the filter member 44.
During use of a conventional respirator~ the user will, by a virtue of movement of the user's head and which may be a relati-,rely rapid movera ent, exert significant kinetic forcss on the respirator. This can cAuse either discomfort to the user, or, lifting of the edges o~ the face piece 12 out of sealing engagement with the user's faee, tllUS permitting inhalahon by the user of contaminated air.
Such a possibility is avoided to the greatest possible extent according to the present inYention by forming the frame 14 as a dihedral, such that all portions of the frame 14 are in as close proaumity to the user~s face as can be arranged. Further, by connecting the ~traps 16 directly to the dihedrally shaped frame 14, further resistence to movement of the frame 14 is provided, in that the straps also will resist any attempted `, ': " :
, , " ~: , ., lateral movement of the ends of the frame 14, or, any attempted rotational movement of the frame 14 about the general central axis of the respirator.
It will be appreciated that the con~truction oE respirator described above is illustrative of a preferred embodiment of the invention and, that vaFious modificatons of that structure may be made without departing from the scope of the appended claims. ~or example, the ribs 24 may be increased in number, and, may be arranged other than radial to the central clamping ring 22, provided, or course, that the ribs 24 retain the unrestricted channels for airflow between~ the ribs and into the central aperture 32.
Also, while the filter retaining member has been shown as having a gener~lly rectangular graticule permitting air nOw to the filter member 44, any other convenient configuration of perforate grid can be provided. Also, any other convenient means for attaching the filter retainer member to the frame 14 can be provided, or, for attaching the frame 14 to the face piece 12.
Central to the inYentive concept of this invention is the provision of concentric inhalation and exhalation valves, which in addition to providing minim~l impedence to air nOw into and out of the face piece, also provide a substantial weight reduction in the total weight of the respirator, as compared to the weight of a respirator having independent exhalation valves, such as are common in the art.
A further advantage accruing from the use of su~h~ concentric inhalation and exh~lation valves is th~ ~y moisture deposited within the face piece by virtue of condensation from the exhaled air of the user will occur dominantly at the exhQl~tion valve 56, at a position in which it readily can be evacuated from the mask by way of the deilector guard 50.

i ' "~ ' Conveniently, the concentric inhalation ~nd ~exhalation valves are die cut in a single operation with the external diameter of the inner aMulus identical to the inner diameter of the outer annulus. Thus perrnitting economy in the manuIacture of the Yal~es simultaneously in a single~strike of the cutting die, and with substantially zero wastflge of materials.
Referring now to ~igure 5, there is illustrated a modification of the respirator of the present invention, in which the filter ~0 is formed as a complete unitary sub-assembly, that is to be snapped onto a snout 62 of a slightly modified form of valve structure.
In Figure 5, the iilter assembly is formed entirely separate from the face piece 12, and is adapted to be snapped onto a snout 62 of the face piece, and subsequently removed therefrom for replacement.
To provide for attachment of the filter sub-assembly, the central ring 22 is extended forwardly of the face piece 12, and, at its ~orward extremity is provided with spring latches 66; such latclles being readily formRble during the molding of the central ring and its associated structures.
As in the previous embodiment, the central ring is provided internally with a spider ~8 on which the extremely fle~ible but dimensionally stable flap valve 26 is located.
Externally, the centr~l ring 22 is provided with a further spider 32a, which supports and positions the central rlng 22 within an opening of a mounting plate 68, the mounting plate 68 providin~ the required attachment 70 to the face piece la.
The filter assembly indicated generally at 60, in this instance is a completely pre-assembled filter unit, that not only incorporates the filter material 44, but which ~lso can incorporate materials for treating air passing . ~. ~ `` `

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through the filter, such as activated carbon, diatornacious earth, or the like, or which can contain textile fibers that have been provided with an electrostatic charge.
The filter 44 is encAsed within Qn extremely thin-walled shell of thermo-ormable plastics sheeting, the rear ace 30 of which h~s been vacuum formed to provide ribs 24a providing air channels as in the previous embodiment, and which extend up to a central opening 32a in the back wa~l 30EI.
The front wall 42a is formed as a perforate surface permitting the passage of eir into and through the filter, the front and rear walls be~ng fused to each other in any convenient mnnner, to provide an enclosing envelope for the contained filter material, and is provided with lugs 16 for the attachment of straps.
In order to replace a used filter assembly with an unused one"t is merely necessary for the user to depress the spring latches 66, in order to remove the filter sub-assembly 60 from the ~ace piece 12 and valve assembly 64, and then to slip a replacement filter sub-assembly over the snout 62 of the face piece.
Various other modifications are contemplated within the scope of the appended claims, the embodiments discussed above being illustrated oslly of preferred embodiments fslling within the scope of the appended claims.

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Claims

Claim:-

1. In a half mask of the type including:
a face piece, a valve assembly rigidly affixed to said face piece and providing an exhalation valve having an inlet and an outlet defining a cylindrical valve seat for an exhalation valve, and, an inhalation valve having an inlet and an outlet defining an annular valve seat for an inhalation valve arranged concentrically with and radially outwardly of said exhalation valve;
valve members cooperating with said respective valve seats; and filter element means in communication with said annular valve seat; the improvement comprising:
said face piece being formed from a resilient and compliant material;
a substantially rigid imperforate wall member integral with and completely surrounding said annular valve seat and extending radially outwardly thereof;
said imperforate wall member terminating at its outer periphery in a continuous peripheral flange extending forwardly of said wall member and then outwardly thereof to define a shallow recess at the front of said wall member;

ribs on said wall member extending forwardly thereof and in directions generally radially of said valve assembly, said ribs defining channels on the front face of said wall member which communicate with said inlet of said annular inhalation valve seat;
a layer of filter material co-extensive with said imperforate wall member and overlying said ribs;
a perforate frame member coextensive with said wall member and overlying said filter material, said frame member having a central opening and a cylindrical extension surrounding said opening for spigotal cooperation with said cylindrical valve seat of said exhalation valve;
latch means integral with said frame member and for latching cooperation with the outwardly extending portion of said wall flange; and, harness attachment means on a rearmost face of said wall for attaching said half mask to the head of a user;
said wall, said filter element and said frame extending laterally toward both sides of said face piece in dihedral formation and presenting a maximized filtering surface area of said filter.