Note: Descriptions are shown in the official language in which they were submitted.
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.
~ I
.' ,'~' ~ .
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.
.
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.
.
~7 \
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.
.
'`
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;
.: ..
.,~
~2~9~
~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.
~.
,:
..
- .
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.
:'' '
I' . ,
.,'
.
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
. ..
::
..
, ;, , .
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.
12
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
. ~. ~ `` `
I
:.
:
\~
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.
14
.: .
~ ' ' ' `"
