Face mask and facepiece therefor

A face mask comprising a substantially planar valve block having a first aperture therethrough containing an inspiratory valve and a second aperture therethrough containing an expiratory valve. The face mask also includes a support member, and a facepiece comprising a flexible, molded member having a substantially planar face of substantially constant thickness and with two apertures therein aligned with the first and second apertures of the valve block. The substantially planar face acts as a gasket between the valve block and the support member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a face mask, particularly, but not 
exclusively, to an aircrew oxygen mask, and a facepiece therefor. 
2. Description of the Prior Art 
In a well-known aircrew oxygen mask, valves are mounted within a complex 
face-seal molding, and the whole mask must be stripped down to carry out 
valve replacement. The problem of frequent face-seal replacement has been 
somewhat alleviated by the use of silicone rubber in place of natural 
rubber, but the complexity of the face-seal moulding still makes the 
continued use of this kind of mask extremely expensive. Furthermore, the 
very complex molds producing the face-seal molding are extremely expensive 
to replace. 
An object of the present invention is to provide a facepiece which is 
easier and less expensive to produce than known face-seal moldings, and to 
provide a face mask incorporating such a facepiece in which valve 
replacement is comparatively simple. 
SUMMARY OF THE INVENTION 
The invention provides a facepiece comprising a flexible, molded member 
having a substantially planar face of substantially constant thickness and 
with apertures therein for gas flow therethrough. 
Preferably, the member is molded from natural or silicon rubber. 
The invention further provides a face mask comprising a substantially 
planar valve block having a first aperture therethrough containing an 
inspiratory valve and a second aperture therethrough containing an 
expiratory valve. The face mask further includes a support member, and a 
facepiece comprising a flexible molded member having a substantially 
planar face of substantially constant thickness and with two apertures 
therein aligned with the first and second apertures of the valve block, 
wherein the substantially planar face acts as a gasket between the valve 
block and the support member. 
Preferably, the valve block has a third aperture therethrough containing an 
anti-suffocation valve aligned with a third aperture in the substantially 
planar face. 
Further, the support member is preferably in the form of an exo-skeleton 
having an inlet and an outlet and the valve block is arranged within the 
confines of the facepiece. 
Preferably, a microphone assembly is removably mounted in the exo-skeleton 
and is aligned with a further aperture in the valve block and a 
corresponding aperture in the substantially planar face. 
In addition, the exo-skeleton preferably carries a removable harness 
assembly for attaching the face mask to a wearer.

DETAILED DESCRIPTION 
With reference, particularly to FIG. 1, an aircrew oxygen mask comprises 
essentially a valve block assembly 1, a facepiece 2, an exo-skeleton 3, a 
microphone and switch assembly 4, and a harness assembly 5. 
The valve block assembly 1 comprises a flat plate-shaped valve block 6 
having four apertures therethrough. A first aperture 7 has a 
stepped-rubber inspiratory valve 8 therein. The valve 8 is mounted in a 
seating molded integrally with the block 6 and comprises a mushroom-shaped 
petal diaphragm 9, which is retained by an integrally molded knob 10 on a 
center stem 11 of the diaphragm 9. An ice guard (not shown) may also be 
provided, e.g., in the form of a molded shield which may be clipped on the 
valve block 6. 
The valve block 6 has a second aperture 12 in which a fully-compensated 
expiratory valve 13 is mounted. A seating and diaphragm-supporting 
structure may be molded integrally with the valve block 6. The valve 13 
comprises a single clip-in cap end molding 14, a spring and a disc (not 
shown). A compensating tube 15 for adjusting back pressure is molded as 
part of the cap molded 14 and is located in a connecting-shaft insert 16 
in the valve block 6. 
The valve block 6 has a third aperture 17 containing an anti-suffocation 
valve 18. A seating 19 is molded integrally with the valve block 6 and the 
valve 18 comprises a cap molding 18a clipped into the aperture 17 to 
retain a spring 18b and a disc 18c (FIG. 3). 
The valve block 6 has a fourth aperture 20 which allows access to the end 
of the microphone assembly 4. 
The facepiece 2 has a flat gasket face 21 having four apertures 22, 23, 24 
and 25 aligned with the apertures 7, 12, 17 and 20, respectively. The 
facepiece 2 may be formed of any suitable flexible material, e.g. molded 
from rubber, but preferably silicone rubber. The facepiece 2 has facial 
contours 26, 27 suitable for a wide range of face sizes and shapes. A nose 
occlusion strip may be provided within the thickness of the molding. In 
practice it has been found that it is only necessary to provide two 
different sizes of facepiece 2. 
The exo-skeleton 3 is injection molded from any suitable material and has 
an air inlet 28, connected to a supply hose 29, and an outlet 30. An 
aperture 31 through the exo-skeleton 3 is aligned with the aperture 25 of 
the facepiece 2 and the aperture 20 of the valve block 6, and accommodates 
the microphone and switch assembly 4. The assembly 4 has a signal cable 32 
and is held in place by means of the harness assembly 5. 
The harness assembly 5 comprises a support plate 33 to which a toggle plate 
34 carrying a flexible steel wire harness 35 is pivotably mounted. The 
support plate 33, the exo-skeleton 3, the gasket face 21 and the valve 
block 6 have aligned screw apertures 36 through which screws 37 pass to 
hold the mask together with valve block 6 secured adjacent the inner 
surface of gasket face 21 and exo-skeleton 3 secured substantially 
adjacent the outer surface of gasket face 21. The mask may be very easily 
dismantled and reassembled for replacement of any of the parts, it being 
only necessary to remove the harness assembly 5 to gain access to the 
microphone switch assembly 4, which may be encased in a plastic molding to 
facilitate handling and assembly.