GB2267647A - A face piece for a face mask - Google Patents

Abstract

A face piece for a face mask to provide breathing air for aircrew. The face piece 28 is soft and flexible, and has an inwardly directed lip 42 biased with a spring 44 to ensure the lip 42 lies flat against the wearer's face. The spring leaf 44 can be stuck to the inside of the lip 42 or embedded within the material of lip 42. The inner edge of lip 42 may be made with a wavy edge which may be of sinusoidal form or of a form having a plurality of adjoining V-shapes. <IMAGE>

Description

A Face Piece for a Face Mask This invention relates to a face piece for a face mask which is intended to provide breathing air to the wearer. Such face masks are used particularly for the aircrew of military aircraft, but the invention is not limited to this application.

A conventional face mask has a soft rubber face piece which fits inside a rigid outer shell. The shell is braced against the back of the wearer's head to pull the face piece against the face so that a peripheral edge of the face piece forms a seal against the face.

In order to form a good seal with the wearer's face it is conventional to provide the peripheral edge of the face piece with an inwardly directed lip so that when the pressure inside the face piece is above ambient, the lip is forced against the face to enhance the effectiveness of the seal. However because of the variation of facial contours between different people, this desirable state of affairs is not always achieved.

According to the invention, there is provided a face piece for a face mask, the face being of a soft, flexible material able to conform to the contours of the face and having a peripheral, sealing edge with an inwardly directed lip, the lip being provided with a spring which biases the lip in a direction outward of the face piece cavity.

A direction outward of the face piece cavity is, in use, a direction towards the wearer's face, and the action of the spring is to ensure that the lip lies flat against the wearer's face whilst the pressure inside the face piece is at ambient. When the pressure inside the face piece subsequently rises above ambient, the pressure will act on the surface of the lip facing away from the wearer's face to force the lip firmly against the face.

The spring can take a number of forms. The spring may act around the whole periphery of the inwardly directed lip, or may act only in specific areas where experience shows that it is most difficult to form a good seal.

The spring may take the form of a layer of material which has a shape memory and which can either be embedded within the material of the face piece, during the moulding thereof, or can be affixed to the interior surface of the face piece after moulding. In one particular embodiment, it has been found that a strip of foamed elastomeric material adhered to the inner face of the face piece and to the inner face of the lip can provide the necessary spring action on the lip.

According to a second aspect of the invention there is provided a face piece for a face mask, the face piece being of a soft, flexible material able to conform to the contours of the face and having a peripheral, sealing edge with an inwardly directed lip, wherein the lip has an inwardly directed free edge which has an undulating or corrugated form.

By providing the free edge of the lip with an undulating or corrugated form, with the undulations or corrugations extending from the free edge towards the peripheral sealing edge of the face piece, it becomes possible to include within the inwardly directed lip more material than would otherwise be present so that when the lip needs to expand to follow the contours of a wearer's face, then this can be done merely by displacement of the material rather than by stretching of the material.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an aviator's face mask when in use; Figure 2 is an exploded view showing the components of the face mask of Figure 1; Figure 3 is a rear view of a face piece for use with a face mask in accordance with the invention; Figure 4 is a cross section through the face piece of Figure 3 on the lines IV-IV; Figure 5 shows the face piece of Figure 4 in position against a wearer's face; Figure 6 is a view corresponding to Figure 3 but showing an alternative embodiment of the face piece; Figure 7 is a section through the face piece of Figure 6 on the lines VI-VI; and Figures 8 and 9 are scrap sections of two alternative embodiments taken in the direction of the arrow A in Figure 7. Figure 1 shows a pilot 10 wearing a flying helmet 12 with a face mask 14. The mask is connected to the helmet 12 by straps 16 which connect to the helmet through sockets 18.

The face mask has a breathing air inlet 20, an air outlet 22 and a microphone location at 24.

In Figure 1, a rigid outer shell 26 and a flexible face piece 28 of the mask can also be seen. Figure 2 shows these two components separated. It will be seen that the shell 26 carries the straps 16 and when the shell is put in position and connected to the helmet, then the face piece 28 is pressed against the pilot's face.

Figure 3 shows face piece 28, as seen from the side of the face piece which will be pressed against the wearer's face.

The face piece has a peripheral sealing edge 40 which will be pressed against the wearer's face. Located internally of the sealing edge 40 is a lip 42 which extends all the way around the edge.

In Figure 4 a cross section through this face piece is shown. On the left hand side the edge 40 and lip 42 are shown in accordance with the prior art; on the right hand side a spring is added to the edge as provided for in accordance with the present invention.

As can be seen in Figure 4, the as-mdulded position of the lip 42 leaves the lip folded slightly inwardly of the face piece. However the effect of applying a spring leaf 44 to the inside of the lip is to lift the lip outwardly of the face piece.

The effect of this is shown in Figure 5 which is a cross section through a face piece 28 pressed against a wearer's face 46. In Figure 5 arrows P represent the pressure which is applied to the face piece during normal use. As can be seen on the left hand side of this Figure where the lip 42 does not initially lie flat against the face, the internal pressure within the face mask can enter between the lip and the face to lift the lip further away from the face to open a leak path. However as can be seen on the right hand side of the Figure where the spring 44 initially provides a force pressing the lip against the face, then the internal pressure in the face piece reinforces the spring pressure and acts only on the back face of the lip to reinforce the seal.

The spring leaf 44 can be stuck to the inside of the lip or embedded within the material of the lip. It can take the form of a metal leaf spring or of any other material which has spring action resulting from a shape memory property of the material. Only a very light spring action is needed, because the material of the face piece itself is soft and as soon as an above ambient pressure P exists inside the face mask, the pressure will act on the inside of the lip 42 and take over the sealing function from the spring leaf 44.

In an alternative embodiment shown in Figures 6 to 9, the inner edge of the lip 42 is made with a wavy edge which is shown in detail over a scrap section of the lip. Two alternative contours for this edge are shown in Figures 8 and 9. One contour (Figure 8) has a sinusoidal form. The other (Figure 9) has a form which is shaped like a plurality of adjoining V-shapes. As can be seen in Figure 6, the waviness runs out before reaching the peripheral sealing edge 40, so that a smooth surface is maintained at this sealing edge.

The effect of the waviness is that there is more material contained in the peripheral lip 42 than would otherwise be the case, and when the internal pressure P acts on the lip to force it against the face, then the material can be displaced to follow the contours of the face, and the material does not have to stretch to follow the contours of the face.

The face piece constructions shown in Figures 3, 4 and 5 and in Figures 6, 7, 8 and 9 can be used together or independently of one another. However both constructions allow the peripheral lip 42 to follow the contours of the face so that the internal pressure inside the face piece can press the lip 42 against the face to reinforce the sealing action of the peripheral lip 40.

Claims (9)

1 A face piece for a face mask, the face piece being of a soft, flexible material able to conform to the contours of a face and having a peripheral, sealing edge with an inwardly directed lip, the lip being provided with a spring which biases the lip in a direction outward of the face piece cavity.

2 A face piece according to claim 1 wherein the spring acts only on a part of the circumference of the lip.

3 A face piece according to claim 1 or claim 2 wherein the spring is in the form of a layer of material which has a shape memory.

d A face piece according to claim 3 wherein the spring is embedded within the material of the face piece during the moulding thereof.

5 A face piece according to claim 3 wherein the spring is affixed to the interior surface of the face piece after moulding.

6 A face piece according to claim 5 wherein the spring is a strip of foamed elastomeric material adhered to the inner face of the face piece and to the inner face of the lip.

7 A face piece for a face mask, the face piece being of a soft, flexible material able to conform to the contours of the face and having a peripheral, sealing edge with an inwardly directed lip, wherein the lip has an inwardly directed free edge which has an undulating or corrugated form.

8 A face piece for a face mask substantially as herein described with reference to any one embodiment shown in the accompanying Figures 1 to 5.

9 A face piece for a face mask substantially as herein described with reference to any one embodiment shown in the accompanying Figures 6 to 9.