U.S. patent number 3,563,236 [Application Number 04/791,830] was granted by the patent office on 1971-02-16 for face pieces for protective masks.
This patent grant is currently assigned to Trelleborgs Gummifabriks Aktiebolag. Invention is credited to Otto Henry Hansson.
United States Patent |
3,563,236 |
Hansson |
February 16, 1971 |
FACE PIECES FOR PROTECTIVE MASKS
Abstract
A face piece for a protective mask is made from a natural or
synthetic rubber or a plastic material and has a solid sealing rib
projecting from the inner side of the face piece to engage the
wearer's face. The width of the sealing rib in the plane of the
face piece is larger than the projection of the rib from the inner
side of the face piece, and the surface of the rib engaging the
wearer's face is profiled to approximately follow the shape of the
skull by varying the thickness of the rib longitudinally and
transversally thereof.
Inventors: |
Hansson; Otto Henry
(Beddingestrand, SW) |
Assignee: |
Trelleborgs Gummifabriks
Aktiebolag (Trelleborg, SW)
|
Family
ID: |
20259183 |
Appl.
No.: |
04/791,830 |
Filed: |
November 20, 1968 |
Foreign Application Priority Data
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Feb 15, 1968 [SW] |
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1979/68 |
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Current U.S.
Class: |
128/201.15;
128/206.24 |
Current CPC
Class: |
A62B
18/02 (20130101) |
Current International
Class: |
A62B
18/02 (20060101); A62B 18/00 (20060101); A61f
009/06 () |
Field of
Search: |
;128/141,141.1,140,142,142.3,142.4,142.5,142.6,172,142.7,185,191,145.5--8,194--5
;2/9,173,174,14,14.20 ;128/141,142,142.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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669,210 |
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Dec 1938 |
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DT |
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425,152 |
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Mar 1935 |
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GB |
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425,744 |
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Mar 1935 |
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GB |
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Mitchell; J. B.
Claims
I claim:
1. A face mask made of a material from the group consisting of
natural rubber, synthetic rubber and plastic materials, said face
mask having an inlet for a clean inhaling gaseous medium, fastening
means for inhaling and exhaling values and for mask fastening
straps, at least one eye lens of clear material, a solid sealing
rib on the inner side of the mask and projecting therefrom, said
sealing rib having a larger width in the plane of the mask than the
thickness of the projection of said rib from the inner side of the
mask, a sealing surface on said sealing rib to engage the wearer's
face, said sealing rib extending in an upward arc from a point
below the midpoint on each side of the mask and being located
between the edge of the mask and said lens, a first bulge on said
sealing rib at the edge thereof closest to said lens from a point
just above the midpoint on each side of the mask, and a second
bulge on said sealing rib at the edge thereof closest to said lens
at the uppermost point of said sealing rib, said sealing surface
being profiled, by varying the thickness of said rib, within the
extent of said first and second bulges, to approximately follow the
shape of the wearer's skull, said first and second bulge being of
sufficient rigidity so as to be capable of being pressed tightly
against the skull to deform the skin and flesh therebetween and
exploit them as sealing means.
2. The mask of claim 1 further having two outward bulges on said
sealing rib at the edge thereof remote from said lens, said outward
bulges approximately conforming to the arch of the broad curved
portion of the frontal bone.
3. The mask of claim 1 further having an outward bulge on said
sealing rib at the edge thereof closest to the lens on a level with
each of the articular processes of the lower jaw beneath the
zygomatic process of the skull.
4. The mask as defined in claim 1 wherein said mask includes means
disposed below said eye lens for attaching said mask to a
protective filter and permitting filtered air to enter said mask
and at least one inlet passage connected to said means and
extending therefrom toward said eye lens to enable all inhaled
filtered air entering said mask to pass over the inner surface of
said eye lens.
5. The mask as defined in claim 4 further having an inner mask
integral with the mask and defined by a baffle extending from the
inner side of the mask below said eye lens to engage the wearer's
face from the jaw-joints to and over the nose.
6. The mask as defined in claim 5 wherein said baffle is provided
with at least one inhaling valve disposed therein, at least one
inhaling passage communicating between said inhaling valve and the
interior of the mask to permit filtered air which has passed over
said eye lens to be inhaled by the wearer of the mask, and an
outlet means in said mask for permitting passage of exhaled air to
the atmosphere.
Description
Face pieces for protective masks must sealingly engage the wearer's
face to make it impossible for the gas against which the wearer
wishes to protect himself to penetrate into the space between the
face and the face piece. To further the sealing action some kind of
sealing means has been used hitherto, and this sealing means
projects from the inner side of the face piece to engage the
wearer's face. The sealing means can have the shape of a hose which
is deformed to a varying extent, thereby taking up variations in
the shape of the face. Use has also been made of sealing means in
the form of a sealing lip or a solid sealing rib which in the use
of the protective mask snugly engages the wearer's face by way of
its elasticity. All these prior-art sealing means are based on the
principle that the shape of the sealing means shall change as a
function of the shape of the wearer's face. Also prior-art sealing
means which are formed as a solid sealing rib whose width is
greater than the distance they project from the face piece, are
based on the principle that the sealing means shall change its
shape as a function of the shape of the wearer's face.
It has been found that the sealing means of the prior-art face
pieces do not ensure the requisite tightness when the protective
masks are used as a protection against the modern nerve gases which
are active in extremely low concentrations. At the tests which have
been carried out by the Royal Swedish Civil Defense Board it has
proved that the so-called adaptation leakage (i.e. the capability
of the sealing means to prevent leakage into the protective mask)
should be lower than 0.01 percent. This implies that the
concentration of war gas in the interior of the mask by reason of
untight fit must be at most one ten-thousandth of the war gas
concentration outside the protective mask.
The object of the present invention is to provide a face piece of a
configuration that will fulfill the above-mentioned requirement.
The invention thus relates to a face piece for a protective mask
which is formed by natural or synthetic rubber or plastic material
and has a sealing rib projecting from the inner side of the face
piece to engage the wearer's face, the width of said rib in the
plane of the face piece being larger than the distance said rib
projects from the inner side of the face piece, and said rib
extends in an upward arc from the jaw-joints, forwardly of the ears
and over the wearer's front, said rib being located between the
edge of the face piece and one or more eye pieces or lenses of
clear material. According to the invention, the sealing rib of said
face piece shall be formed with varying thicknesses so that the
side of the sealing rib which is turned towards the wearer's face
will have a profile that approximately follows the shape of the
skull.
For better elucidation, the invention will be more fully described
in the following with reference to the accompanying drawings in
which:
FIG. 1 is a rear view of a preferred embodiment of the face
piece;
FIGS. 2--7 are sections on lines II--II, III--III, IV--IV, V--V,
VI--VI and VII--VII, respectively, in FIG. 1.
In the illustrated embodiment the face piece of the protective mask
has an eye piece or lens 11 common to both eyes and consisting of
some clear plastic material, e.g. acryl glass. The lens 11 is
gas-tightly connected to the face piece in some suitable manner; in
the embodiment illustrated the lens is glued into a groove provided
in the face piece. In addition, the face piece has a fastening
device 12 for a protective filter (not shown) which is retained in
the fastening device in some suitable manner. From the space of the
fastening device rearwardly of the protective filter there extend
two inlet passages 13 which open at the lower edge of the lens 11
so that all inhaling air has to flow in an upward direction over
the inner side of the lens 11. From the inner side of the face
piece extends a baffle 14 which in the use of the mask engages the
wearer's face in a gastight manner in the region between the cheek
bones and over the root of the nose. Together with the portions 15
of the face piece which engage the wearer's face in the region from
the cheek bones over the cheeks and around the chin, said baffle 14
forms an inner mask which is thus integral with the face piece
proper. Besides the face piece has two inhaling passages 16 which
extend from the lower edge of the lens 11 in between the baffle 14
and the main portion of the face piece, each of said inhaling
passages leading to an inhaling valve 17 which is fastened in a
suitable manner to the inner side of the baffle 14. The face piece
also has a fastening device 18 for an exhaling valve (not shown) .
Said valve is located at the lowermost portion beneath the
wearerchin and is arranged so as to ensure self-drainage.
In a known manner the face piece of the protective mask has five
fastenings 19--23 for mask fastening straps which are not shown in
the drawings. At the edge of the face piece there is provided a
solid sealing rib 24 which projects from the inner side of the face
piece to engage the wearer's face. The sealing rib 24 extends in an
upward arc from the jaw-joints, forwardly of the ears and over the
front and will thus be located between the edge of the face piece
and the lens 11. As will appear from the drawings the width of said
sealing rib in the plane of the face piece is greater than the
distance it projects from the inner side of the face piece.
The sealing means according to the invention is based upon another
principle than the prior-art deformable sealing means. The
principle underlying the invention is that the skin and the flesh
between the sealing rib and the skull shall be exploited as sealing
means for attaining a fully satisfactory tightness of engagement.
This is realized by shaping the profile of the sealing rib in
conformity with the shape of the skull. As will appear from FIG. 5,
the sealing rib thus is higher at the edge closest to the lens 11
at a level with the temporal cavities of the skull which lie
forwardly of the ears. By the term "temporal cavities" is
understood the hollow portion of the squamous part (pars squamosa
ossis temporalis) above the zygomatic process (processus
zygomaticus) on each side of the skull. Moreover, as will appear
from FIG. 3, the sealing rib at the edge closest to the lens 11 has
a bulge conforming to the cavity in the frontal bone above the root
of the nose. The contemplated cavity is that formed by the nasal
portion (pars nasalis) of the broad curved portion (squama
frontalis) of the frontal bone. It is also advantageous if, as will
appear from FIG. 4, the sealing rib at the edge remote from the
lens 11 has a gentle outward bulge conforming to the arch of the
broad curved portion (squama frontalis) of the frontal bone.
As will appear from FIG. 6, the sealing rib 24 has been made
slightly higher at the edge closest to the lens 11 on a level with
the articular process (processus articularis) of the lower jaw
beneath the zygomatic process so that a fully satisfactory seal is
ensured also at this point. Beneath this point of the sealing rib
the said rib successively merges into a rib having the same height
at both edges and successively diminishing in thickness. This is
illustrated by the section shown in FIG. 7.
The difference in height between the two edges of the sealing rib
suitably is as follows: 2 to 3 mm in the section of FIG. 3, 0.5 to
1 mm in the section of FIG. 4, 3.5 to 4.5 mm in the section of FIG.
5, and 0.5 to 1 mm in the section of FIG. 6. There is no difference
in height in the section shown in FIG. 7.
Of the above-mentioned outward bulges provided on the sealing rib
24 those at the temporal cavities are the most important for
obtaining a satisfactory tightness of engagement. The bulge at the
frontal bone cavity is not always necessary, for it is very well
possible to arrange the sealing rib at a higher level at the
wearer's front where there is no cavity in the frontal bone.
However, the sealing rib is preferably placed just above the
eyebrows since this will make the space between the face piece and
the face smaller.
Experiments have shown that a face piece which is designed in
accordance with the present invention provides a fully satisfactory
seal against the faces of various individuals although the shape of
the face varies from individual to individual. The explanation
is--as more thorough investigations have shown--that the shape of
the skull, specifically the location of the said temporal and
frontal bone cavities differs only insignificantly from individual
to individual although the outer contours of the face may vary
greatly. The differences, if any, between the shapes of the skulls
of different individuals is equalized on the one hand by the face
piece of elastic material being deformed when it is clamped to the
face and on the other hand by the sealing rib moving aside the skin
and the flesh which will thereby serve as sealing means between the
face and the face piece. It should be mentioned, however, that--as
is the case with all previously known face pieces--the intention of
course is to manufacture the face piece of the present invention in
several sizes to permit the selection of a face piece of a suitable
size with due consideration of the size of the skull.
* * * * *