GB2408213A

GB2408213A - Respirator mask with adjustable visor

Info

Publication number: GB2408213A
Application number: GB0401650A
Authority: GB
Inventors: Joseph Anthony Griffiths
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-24
Filing date: 2004-01-26
Publication date: 2005-05-25
Also published as: GB0401650D0; GB0327286D0

Abstract

A respirator mask is disclosed. It comprises a shell 3, a flexible oro-nasal mask 4 mounted within the shell 3 adapted to surround a wearer's nose and mouth to make an airtight seal therewith, and a rigid outer faceplate 2 having a first portion 2a that extends over and is pivotally connected to the shell 3. The faceplate has a second transparent visor portion 2b that extends in front of the wearer's eyes in their line of sight. The first portion 2a of the faceplate 2 includes an adjustment mechanism 7 thereon which is operable by the wearer to incrementally adjust the angular position of the faceplate 2 relative to the shell 3 and retain it in a selected angular position to control the distance of the transparent visor portion 2a of the faceplate 2 from the wearer's eyes.

Description

24082 1 3 Respirator Mask With Adjustable Visor This invention relates to

a respirator mask which incorporates a transparent visor compatible with helmet mounted electro-optical sighting devices such as, for example, night vision goggles (NVG). However, the facemask of the present invention is not exclusively designed for use with NVG's, and can be used with other helmet mounted devices. The facemask of the invention is particularly suitable for use by aircrew, especially those of fighter aircraft.

Some helmet mounted electro-optical sighting devices project their images onto a visor located in front of the wearer's eyes. To work satisfactorily, the distance between the nearest display surface of the sighting device and the wearer's eyes (known as eye relief) is critical if the images are to be in focus, and clearly visible with the optimum field of view to the wearer. Some facemasks currently available comprise a rigid outer shell in which a flexible oro-nasal mask is mounted, which covers the wearer's nose and mouth, and include a visor formed as part of the rigid outer shell. Oxygen or another breathable gas is supplied to the wearer through this flexible mask. A protective rubber hood (known as an 'NBC' hood -'Nuclear- Biological - Chemical') can be attached to the top and sides of the visor as well as to the periphery of the rigid front shell to enclose the wearer's head, and is intended to be worn underneath the wearer's helmet. A problem with this prior art respirator is that the eye relief dimension is neither fixed nor adjustable. For instance, if the wearer has a pronounced forwardly extending chin, the bottom of the oxygen mask and thus the rigid shell and the visor extending upwardly from it will be inclined at a lesser angle to the wearer's eyes than it would be if he has a receding chin. Thus, with a protruding chin, the top of the visor will be tilted closer to the wearer's eyes whereas with a receding chin, it will be tilted further away from them.

In an attempt to overcome this problem, some systems use a separate visor discrete from the rigid outer shell of the mask, which is attached to the NBC hood along the visor's top, side and bottom edges, the hood extending over the rigid outer shell of the breathing mask to enclose it completely. However, the problems with these systems are: - 2 a) the eye relief distance and the distance between the visor and the sighting device, is random and non-adjustable; b) the visor can move after the initial positioning of the visor and hood combination during dressing, (for instance, if worn by aircrew in flight when subjected to high G forces) so the visor may end up being too far away from the wearer's eyes to permit the proper use of electro-optical devices. I;or NVG's to work properly, the preferred eye relief distance should be between 1 5mm and 30mm.

It is therefore an object of the present invention to provide a respirator mask that includes a visor, which overcomes these problems.

According to the present invention, there is provided a respirator mask comprising a shell, a flexible oro-nasal mask mounted within the shell adapted to surround a wearer's nose and mouth to make an airtight seal therewith, and a rigid outer faceplate having a first portion that extends over and is pivotally connected to the shell and a second transparent visor portion that extends in front of the wearer's eyes in their line of sight, wherein the first portion of the faceplate includes an adjustment mechanism thereon which is operable by the wearer to incrementally adjust the angular position of the faceplate relative to the shell and retain it in a selected angular position to control the distance of the transparent visor portion of the faceplate from the wearer's eyes.

In a preferred embodiment, the shell and the first portion of the faceplate include cooperating means to pivotally attach the faceplate to the shell.

Ideally, the cooperating means comprises a boss protruding from the shell which locates between a pair of shoulders upstanding from the first portion of the faceplate, and a hinge pin which locates in a hole extending through the boss and each of the shoulders when the boss is located therebetween.

Preferably, the adjustment mechanism comprises at least one rod extending through and threadingly received in the first portion of the faceplate, the or each rod being - 3 in contact with the shell such that rotation thereof draws the faceplate closer to or away from the wearer's face.

Preferably, the axis of rotation of the rod is substantially at right angles to the axis about which the faceplate pivots relative to the shell and is offset therefrom.

In a particularly preferred embodiment, the adjustment mechanism comprises two threaded rods, the axis of rotation of each rod being substantially at right angles to the axis about which the faceplate pivots relative to the shell, the axis of each rod being offset from the axis of rotation of the faceplate relative to the shell by the same distance but in opposite directions.

The or each rod conveniently has an enlarged head portion to facilitate manipulation by the wearer.

A seat is preferably formed on the shell against which a rod makes contact during rotation thereof.

In an alternative embodiment, the adjustment mechanism comprises at least one toothed ratchet bar extending from the rigid shell through the outer faceplate and a cooperating engagement member located on the outer faceplate in engagement with the ratchet teeth operable to draw the faceplate closer to, or away from, the wearer's face.

The cooperating means advantageously includes a mechanism to adjust the lateral distance of the faceplate relative to the rigid shell in addition to its angular orientation.

In one embodiment, the mechanism includes means for sliding the hinge pin towards or away from the wearer's face.

In an alternative embodiment, the co-operating means comprises a boss protruding from the shell which locates within a co-operating portion of the outer faceplate - 4 and a hinge sleeve that extends through horizontal co-axially aligned apertures in the boss and the co-operating portion of the outer faceplate.

In this alternative embodiment, the adjustment mechanism preferably comprises a s threaded rod extending through a bush in the outer faceplate and axially fixed with respect to the outer faceplate and received in a threaded aperture in the boss, such that rotation of the threaded rod draws the faceplate closer to or further away from the wearer's face.

Conveniently, one end of the hinge sleeve is connected to a source of drinkable liquid, the opposite cod is sealed, and there is an aperture between the ends of the hinge sleeve which is connected to a drinking tube that extends through the rigid shell and the flexible oro-nasal mask, positionable adjacent the wearer's mouth, such that the drinkable liquid can be supplied from the source to the wearer's mouth.

The hinge sleeve preferably includes O-rings either side of the aperture between the hinge sleeve ends to prevent the drinkable liquid from leaking out of the horizontal aperture in the boss Preferably, the range of angular movement of the outer faceplate relative to the rigid shell is 30 .

In a preferred embodiment the respirator mask includes a harness to attach the respirator mask to a helmet.

The harness is advantageously connected to the faceplate and, preferably, to a point on the outer faceplate which is laterally spaced from the axis about which the faceplate may pivot relative to the shell in a direction away from the wearer's face.

The harness is preferably made from a non-extensible material so that the outer faceplate and the rigid shell attached thereto remains at a fixed distance from the helmet and the wearer's face. - 5

In a preferred embodiment, the faceplate includes a peripheral edge which is attached to the opening in the front of a protective hood so that the wearer's head is enclosed within the hood.

s Advantageously, the hood is made from a NBC (Nuclear, Biological, Chemical) resistant material.

Preferably, the hood includes means, in a region adjacent to where it joins the peripheral edge of the faceplate, to allow the faceplate to pivot relative to the shell.

In a preferred embodiment, the oro-nasal mask includes extcodable means adjacent the peripheral edge thereof and within the rigid shell, and a source of pressurised breathable gas connected to the interior of the mask controlled by a regulator which supplied gas at a pressure proportional to G-forces that it is subjected to, operable to expand the extendible means when pressurised gas is supplied to the interior of the mask to press the periphery of the mask towards the wearer's face and improve the seal therewith.

The extendable means in the bottom portion of the mask are preferably configured to extend more than the extendable means in the top portion of the mask so that when the extendable means are caused to expand by the supply of pressurised breathable gas, the bottom of the mask is moved away from the wearer's face by a greater amount than the top portion, thereby pivoting the mask upwards about a pivot point at which the respirator is attached to a wearer's helmet The flexible oro-nasal mask may be made from a natural or synthetic rubber material.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front view of a first embodiment of a respirator mask of the present invention; - 6 Figure 2 is a side view of a respirator mask show in Figure 1; Figure 3 is an exploded perspective view of the respirator mask of Figures 1 and 2; I:igure 4 is a cross- sectional view along the line X-X of the respirator shown in Figures I to 3, in position on a wearer's face and also including an NBC hood attached to the respirator; Figure 5 is a front view of a second embodiment of a respirator mask according to the present invention; and Figure 6 is a cross sectional view along the line Y - Y of the respirator mask shown in Figure 5, in position on a wearer's face and also including an NBC hood attached to the respirator.

Referring now to Figures 1 - 4, there is shown a first embodiment of a respirator mask 1 comprising an outer faceplate 2, a rigid mask shell 3 having a peripheral rim 3a, and a flexible oro-nasal mask 4. The flexible oro-nasal mask 4 is mounted within the rigid shell 3 and has a periphery 4a adapted to make a seal around a wearer's nose and mouth, which extends beyond the peripheral rim 3a of the rigid shell 3.

The outer faceplate 2 comprises an upper visor portion 2a and a lower face portion 2b, and is pivotally mounted to the rigid shell 3. The upper visor portion 2a is such that, in use, it is positioned in the wearer's line of sight. The outer faceplate 2 also includes a harness 6 to enable the respirator mask to be attached to a helmet of, for example, a pilot. The harness 6 is made of an inextensible material, such a wire or a webbing material, and includes adjustment means (not shown) to enable its length to be altered to that the flexible oro-nasal mask rests comfortably on the wearer's face.

The respirator mask I includes inspiratory and expiratory valves (not shown) in a known manner, and a breathable air supply (not shown) such as oxygen or air is connected to the respirator mask in a known manner.

The outer faceplate 2 is attached to the rigid shell 3 by a pivot mechanism 7, which allows the outer faceplate 2 to pivot relative to the rigid shell 3 about a horizontal - 7 axis, so that in use, the visor portion 2a can be moved towards and away from the wearer's face.

The pivot mechanism 7 comprises at least one hinge portion 7a extending from an s inside surface of the outer faceplate 2 towards the rigid shell 3, and at least one cooperating hinge portion 7b extending from an outer surface of the rigid shell 3 towards the inside surface of the outer faceplate 2. Each hinge portion 7a, 7b includes an aperture 8a, 8b extending horizontally therethrough, and the two cooperating hinge portions 7a, 7b can be positioned adjacent one another so that their respective apertures 8a, 8b are coaxially aligned and a hinge rod 9 can pass through the apertures 8a, 8b to pivotally connect the outer faceplate 2 and the rigid shell 3 as mentioned above. However, alternative hinge configurations may be employed within the scope of the invention.

The pivot mechanism 7 also includes adjustment means 10 comprising threaded screw rods 10a which are received in threaded apertures 10b that extend from the front of the outer faceplate 2 to contact the rigid shell 3 behind it. One threaded rod 10a is positioned on either side of the hinge rod 9 and each has an end tip 11 that touches a contact point 12 outer surface of the rigid shell 3. The heads 13 of the threaded rods 10a on the outside of the outer faceplate 2 include portions to enable them to be more easily manipulated and rotated, for example lateral wing portions or ridged edge surfaces.

The respirator mask 1 is adapted to be used in conjunction with a protective hood 15 (see Figure 4). I'he protective hood is designed to shield the wearer from the effects of nuclear fallout, biological and chemical weapons, and is known as an NBC hood'. The hood fits over the wearer's head and has a hole in the face portion. I'he outer faceplate 2 is provided with a peripheral edge portion 16 to which the edge of the NBC hood 15 around the hole can be bonded. 'I'he NBC hood 15 also includes extendable portions adjacent to the peripheral edge 16 of the outer faceplate 2 which prevent the NBC hood 15 from hindering the pivotal movement of the outer faceplate 2. - 8

In use, the hood 15 and respirator 1 arc fitted over the wearer's head so that the periphery 4a of the flexible oro-nasal mask 4 locates around the wearer's nose and mouth and the visor 2a is in the line of sight of the wearer. The wearer then puts on a helmet (not shown) over the hood, and attaches the respirator mask 1 to the helmet by the harness 6 and uses the adjustment means (not shown) to alter the length of the harness 6 so that the periphery 4a of the flexible oro-nasal mask 4 is held against the wearers face and makes a seal therewith. The harness is made form an inextensible material, as mentioned above, and so the rigid shell 3 is held in a fixed position relative to the wearer's face.

The helmet will include an electro-optical sighting device which will be positioned in front of the wearer's eyes beyond the visor 2a. In order for the sighting device to work properly and the images projected onto the visor 2a to be in focus for the wearer, the visor 2a must be positioned at the optimum distance between the wearer's eyes and the sighting device. This is achieved by pivoting the outer faceplate 2 relative to the rigid shell 3. If the upper threaded screw rod 10a on the front of the outer faceplate 2 is rotated clockwise, it will screw inwards towards the rigid shell 3 and the end tip 11 will press against the contact point 12 above the hinge rod 9. This force will exert a rotational moment about an axis extending through the hinge rod 9 causing the outer faceplate 2 to tilt in the direction of arrows A (see Figure 4) so that the visor 2a moves away from the wearer's face. To allow the outer faceplate 2 to rotate in this direction, it may also be necessary to rotate the lower threaded rod 10a anti-clockwise to screw it outwards away from its contact point 11 on the rigid shell 3.

Conversely, to tilt the visor portion 2a of the outer faceplate 2 towards the wearer's face in the direction of arrows B. the lower threaded rod 10a is rotated clockwise to screw inwards towards its contact point on the rigid shell 3, whilst the upper threaded rod 10a may be rotated anticlockwise to screw outwards away from the rigid shell 3.

As the outer faceplate 2 is tiled in either direction, the extendable means 17 of the NB(: hood 15 around the peripheral edge 1(j of the outer faceplate 2 flex and stretch to accommodate the range of movement without hindering it.

When the user has positioned the outer faceplate 2 in the required optimum position by rotating one of the threaded rods lea, the other threaded rod 10a can be adjusted to ensure that the tip 11 is in contact with its respective contact point or seat 12 to thereby retain the outer faceplate 2 in the desired angular position.

Although the adjustment means 10 of the above embodiment comprises threaded rods 10a which arc received in threaded holes 10b in the outer faceplate 2, the adjustment means 10 may comprise an alternative arrangement, for example, toothed ratchet bars rigidly attached to and extending from the outer surface of the rigid shell 3, through apertures in the outer faceplate 2. In this embodiment, the outer faceplate 2 includes latch members which releasably engage with the teeth of the ratchets to hold the outer faceplate 2 in a fixed position relative thereto. As with the threaded rod arrangement described above, one ratchet bar would preferably be located above the hinge bar 9, and one below the hinge bar 9, although since each ratchet and latch mechanism, when engaged, would prevent the outer faceplate from pivoting in either direction towards and also away from the wearer's face, it is not essential that at least one ratchet and latch mechanism is positioned either side of the pivot mechanism.

In a further unillustrated embodiment, it is envisaged that the respirator mask may include a mechanism connecting the rigid shell and the outer faceplate to allow the outer faceplate to move in a lateral fore-aft direction, towards and away from the wearer's face in use, as well as the pivot mechanism described above. For example, the hinge bar 9 may be mounted so that it can move laterally toward and away from the wearer's face by screwing both rods 10a in or out by the same amount.

However, it will be appreciated that additional rotation of one of said rods 10a relative to the other rod 10a is operable to adjust the angular position of the faceplate relative to the shell and the wearer's face. 10

Referring now to Figures 5 & 6, a respirator mask 21 is shown of a second embodiment of the present invention, comprising an outer faceplate 22, a rigid mask shell 23 having a peripheral rim 23a, and a flexible oro-nasal mask 24. The flexible oro-nasal mask 24 is mounted within the rigid shell 23 and has a periphery 24a adapted to make a seal around a wearer's nose and mouth, which extends beyond the peripheral rim 23a of the rigid shell 23.

The outer faceplate 22 comprises an upper visor portion 22a and a lower face portion 22b, and is pivotally mounted to the rigid shell 23. The upper visor portion 22a is such that, in use, it is positioned in the wearer's line of sight. The outer faceplate 22 also includes a harness 26 to enable the respirator mask to be attached to a helmet of, for example, a pilot. The harness 26 is made of an inextensiblc material, such a wire or a webbing material, and includes adjustment means (not shown) to enable its length to be altered so that the flexible oro-nasal mask rests comfortably on the wearer's face. The harness 26 is attached to the outer faceplate 22 through a horizontal harness aperture 38 in the centre of the front of the faceplate 22.

The respirator mask 21 includes inspiratory and expiratory valves (not shown) in a known manner, and a breathable air supply (not shown) such as oxygen or air is connected to the respirator mask in a known manner.

The outer faceplate 22 is attached to the rigid shell 23 by a pivot mechanism 27, which allows the outer faceplate 22 to pivot relative to the rigid shell 23 about a horizontal axis, so that in use, the visor portion 22a can be moved towards and away from the wearer's face. It will be noted that the outer faceplate 22 of the second respirator embodiment 21 does not extend down as far as the outer faceplate 2 of the first respirator embodiment 1.

The pivot mechanism 27 comprises a boss 27a extending from the outer surface of the rigid shell 23, and a co-operating portion 27b of the outer faceplate 22. The co- operating portion 27b is shaped to sit over the boss 27a so that the boss 27a locates between vertical side walls 27c of the co-operating portion 27b. A hole 28a extends - 11 through the boss 27a and is coaxially aligned with two holes 28b, one in each side wall 27c of the co-operating portion 27b. A hinge sleeve 29 passes through the apertures 28a, 28b to pivotally connect the outer faceplate 22 and the rigid shell 23.

s A drinking facility tube 39 is connected through the rigid shell 23 and flexible mask 24 and terminates in a mouthpiece 39a located adjacent the wearer's mouth (see Figure 6). One end of the hinge sleeve 29 is sealed closed and the other end is connected to a drink supply pipe 40 which terminates in a connector 40a. The hinge sleeve 29 has an aperture 29a through its wall midway along its length which aligns with the end of the drinking facility tube 39 distal from the pilot's mouthpiece 39a.

The hinge sleeve 29 includes O-rings 41 either side of the aperture 29a. The connector 40a is used to connect the supply pipe 40 to a source of drinking fluid (not shown). In use, the pilot is able obtain liquid refreshment by sucking on the mouthpiece 39a which draws drinking fluid from the supply through the supply pipe 40, through the hinge sleeve 29, out of the aperture 29a and through the drinking facility tube 39 to the pilot's mouth. The drinking fluid is prevented from leaking out of the aperture 28a in the boss 27a of the rigid shell 23 by the seal the O-rings 41 make with the internal surface of the aperture 28a in the boss 27a.

The pivot mechanism 27 also includes adjustment means 30 comprising a threaded screw rod 30a which is received in a bush in the outer faceplate 22 and is thereby held in a fixed position with respect to the outer faceplate 22. The threaded rod 30a is received in a threaded aperture 30b in the boss 27a of the rigid shell 23. The threaded rod 30a is positioned above the hinge rod 29 and has a head 33 on the outside of the outer faceplate 22 that includes a portion to enable it to be easily manipulated and rotated, for example, the enlarged ridged head shown in Figures 5 and 6, or alternatively, lateral wing portions.

The respirator mask 21 is adapted to be used in conjunction with a protective hood 35 (see Figure 6). The protective hood is designed to shield the wearer from the effects of nuclear fallout, biological and chemical weapons, and is known as an NBC hood'. The hood fits over the wearer's head and has a hole in the face portion. The outer faceplate 22 is provided with a peripheral edge portion 36 to - 12 which the edge of the NBC hood 35 around the hole can be bonded. The NBC hood 35 also includes extendable portions 37 adjacent to the peripheral edge 36 of the outer faceplate 22 which prevent the NBC hood 35 from hindering the pivotal movement of the outer faceplate 22. s

In use, the hood 35 and respirator 21 are fitted over the wearer's head so that the periphery 24a of the flexible oro-nasal mask 24 locates around the wearer's nose and mouth and the visor 22a is in the line of sight of the wearer. The wearer then puts on a helmet (not shown) over the hood, and attaches the respirator mask 21 to the helmet by the harness 26 and uses the adjustment means (not shown) to alter the length of the harness 26 so that the periphery 24a of the flexible oro-nasal mask 24 is held against the wearers face and makes a seal therewith. The harness is made from an inextensible material, as mentioned above, and so the rigid shell 23 is held in a fixed position relative to the wearer's face.

The respirator mask 21 is designed to operate under high G-force conditions, as it would be subjected to in use in modern fighter aircraft. In such use, the pilot is subjected to forces of up to 9G during extreme manoeuvres, and to prevent the pilot from blacking out though lack of oxygen or experiencing 'G-LOC' (G-force, Loss Of Consciousness) high pressure breathing gas must be supplied to the mask, and the mask seal around the pilot's nose and mouth must not leak. The respirator 21 therefore includes the features disclosed in the Applicant's earlier patent application numbers GB 0218705.2 and GB 0221687.7. These will be briefly described below: A source of pressurised breathable gas (not shown) is connected to the interior of the oro-nasal mask 24. This is controlled by a regulator (not shown) that increases the pressure of the breathable gas supplied in proportion to the G-I7orce exerted on the aircraft and the pilot. The flexible oro-nasal mask 24 includes extendible bellows portions 24b adjacent its periphery 24a but not extending beyond the peripheral edge 23a of the rigid shell 23. The purpose of the extendible bellows portions is to enable the peripheral edge 24a of the oro-nasal mask 24 to move in a direction generally parallel to the wall of the rigid shell 23 when pressurised breathable gas - 13 is supplied to the interior of the mask as a result of the regulator being activated when the aircraft makes a turn. When the pressure supplied to the interior of the mask 24 increases, the wall of the flexible mask 24 extends to cope with the increased pressure. As the wall of the flexible oro-nasal mask 24cannot move s radially outwardly because it is contained within the rigid shell 23 which is secured to the pilot's face by the harness 26, it can only move in a direction generally towards the pilot's face (see Figure 6) and thereby improves its seal therewith.

lo It will be noted that the bellows portion 24b at the top portion of the wall of the oro-nasal mask 24 is smaller than the bellows portion 24b in the bottom part of the mask. The effect of providing varying sized bellows portions 24b is that when the high pressure breathable gas is supplied to the interior of the mask 24, the bellows 24b in the bottom half of the mask 24 are able expand significantly more that the bellows 24b in the upper portion of the mask 24. Although the rigid shell 23 is constrained by the harness 26, it is able to pivot about the axis of the harness aperture 38 away from the pilot's chin to compensate for additional expansion in the lower part of the mask 24 relative to that in the upper part of the mask. Accordingly, it will be seen that when the pilot makes a high G-force turn, the flexible oro-nasal mask 24 expands and the rigid shell 23 pivots as the pressure of the breathable gas supplied to the interior of the flexible mask 24 increases and the bellows 24b expand. Thus, the edge seal is maintained with the pilot's face at all times during the turn so he is supplied with the required amount of high pressure breathable gas that he needs to avoid blacking out.

The helmet will include an electro-optical sighting device which will be positioned in front of the wearer's eyes beyond the visor 22a. In order for the sighting device to work properly and the images projected onto the visor 22a to be in focus for the wearer, the visor 22a must be positioned at the optimum distance between the wearer's eyes and the sighting device. Once the respirator mask is in position on the pilot's face, this optimum visor position is achieved by pivoting the outer faceplate 22 relative to the rigid shell 23. This is done by rotating the threaded screw rod 30a 14 on the front of the outer faceplate 22 to screw inwards or outward of the thtcaded aperture 30b in the rigid shell 23. Clockwise rotation of the threaded screw rod 30a screws the rod 30a into the threaded aperture 30b in the rigid shell 23. As the threaded screw rod 30a is held in a fiend position relative to the outer faceplate, this is pivots the visor portion 22a of the outer faceplate 22 about the hinge sleeve 29 towards the wearer's face in the direction shown by arrow B in Figure G. Conversely, to tilt the visor portion 22a of the outer faceplate 22 away from the wearer's face in the direction of arrows A, the threaded rod 30a is rotated anti- clockwisc to screw out of the threaded aperture 30b. As the outer faceplate 22 is tiled in either direction, the extendable

means 37 of the NBC hood 35 around the peripheral edge 36 of the outer faceplate 22 flex and stretch to accommodate the range of movement without hindering it.

It has been found that although the mask 24 and rigid shell 23 tilt as described above when high pressure breathable gas is supplied to the mask 24 when a pilot makes a high-G turn, the degree to which the visor 22a is caused to move relative to the pilot's eyes is too insignificant to have any effect on the operation or focus of any electro optical devices that projects images onto the visor screen 22a.

Although the adjustment means 30 of the above embodiment comprises a threaded rod 30a, the adjustment means 30 may comprise an alternative arrangement, for example, a toothed ratchet bar rigidly attached to and extending from the outer surface of the rigid shell 23, through an aperture in the outer faceplate 22. In this embodiment, the outer faceplate 22 includes a latch member which releasably engages with the teeth of the ratchet to hold the outer faceplate 22 in a fixed position relative thereto.

It will be appreciated that the respirator masks 1/21 described above can work equally well in with respect to the electro-optical sighting device without incorporating the NBC hood as described. -

The visor portion 2a/22a of the above embodiments of the invention provides the wearer with the additional benefit of an eye shield, as well as the primary function for use with electro-optical sighting devices. This is useful in the event of a collision where the mounting system for the sighting devices arc often designed to break away from the helmet. In such a scenario, the sighting device may be forced towards the pilot's face, and so the visor 2a would prevent the sighting device injuring the wearer. The shield function would also be of use in preventing injury, if a foreign object was to break through a wind-screen of an aircraft and strike the wearer in the head. - 16

Claims

Claims 1. A respirator mask comprising a shell, a flexible oro-nasal mask

mounted within the shell adapted to surround a wearer's nose and mouth to make an airtight seal therewith, and a rigid outer faceplate having a hrst portion that extends over and is pivotally connected to the shell and a second transparent visor portion that extends in front of the wearer's eyes in their line of sight, wherein the first portion of the faceplate includes an adjustment mechanism thereon which is operable by the wearer to incrementally adjust the angular position of the faceplate relative to the shell and retain it in a selected angular position to control the distance of the transparent visor portion of the faceplate from the wearer's eyes.
2. A respirator mask according to claim 1 wherein the shell and the first portion of the faceplate include cooperating means to pivotally attach the faceplate to the shell.
3. A respirator according to claim 2, wherein the cooperating means comprises a boss protruding from the shell which locates between a pair of shoulders upstanding from the first portion of the faceplate, and a hinge pin which locates in a hole extending through the boss and each of the shoulders when the boss is located therebetween.
4. A respirator mask according to any preceding claim, wherein the adjustment mechanism comprises at least one rod extending through and threadingly received in the first portion of the faceplate, the or each rod being in contact with the shell such that rotation thereof draws the faceplate closer to or away from the wearer's face.
A respirator mask according to claim 4, wherein the axis of rotation of the rod is substantially at right angles to the axis about which the faceplate pivots relative to the shell and is offset therefrom. - 17
6. A respirator mask according to claim 4, wherein the adjustment mechanism comprises two threaded rods, the axis of rotation of each rod being substantially at right angles to the axis about which the faceplate pivots relative to the shell, the axis of each rod being offset from the axis of rotation of the faceplate relative to the shell by the same distance but in opposite directions.
7. A respirator according to any of claims 4 to G. wherein the or each rod has a head portion to facilitate manipulation by the wearer.
8. A respirator according to any of claims 4 to 7, wherein a seat is formed on the shell against which a rod makes contact during rotation thereof.
9. A respirator mask according to claim 2 wherein the adjustment mechanism comprises at least one toothed ratchet bar extending from the rigid shell through the outer faceplate and a cooperating engagement member located on the outer faceplate in engagement with the ratchet teeth operable to draw the faceplate closer to, or away from, the wearer's face.
10. A respirator mask according to any of claims 2 to 9, wherein the cooperating means include a mechanism to adjust the lateral distance of the faceplate relative to the rigid shell in addition to its angular orientation.
11. A respirator according to claim 10, wherein the mechanism includes means for sliding the hinge pin towards or away from the wearer's face.
12. A respirator according to claim 2 wherein the co-operating means comprises a boss protruding from the shell which locates within a cooperating portion of the outer faceplate and a hinge sleeve that extends through horizontal co-axially aligned apertures in the boss and the cooperating portion of the outer faceplate.
13. A respirator according to claim 12 wherein the adjustment mechanism comprises a threaded rod extending through a bush in the outer faceplate and axially fixed with respect to the outer faceplate and received in a threaded aperture in the - 18 boss, such that rotation of the threaded rod draws the faceplate closer to or further away from the wearer's face.
14. A respirator according to claim 12 or claim 13 wherein one end of the hinge s sleeve is connected to a source of drinkable liquid, the opposite end is sealed, and there is an aperture between the ends of the hinge sleeve which is connected to a drinking tube that extends through the rigid shell and the flexible oro-nasal mask, positionable adjacent the wearer's mouth, such that the drinkable liquid can be supplied from the source to the wearer's mouth.
15. A respirator according to claim 14 wherein the hinge sleeve includes O-rings either side of the aperture between the hinge sleeve ends to prevcut the drinkable liquid from leaking out of the horizontal aperture in the boss.
16. A respirator mask according to any preceding claim wherein the range of angular movement of the outer faceplate relative to the rigid shell is 30 .
17. A respirator mask according to any preceding claim including a harness to attach the respirator mask to a helmet.
18. A respirator mask according to claim 17, wherein the harness is connected to the faceplate.
19. A respirator mask according to claim 18, wherein the harness is attached to a point on the outer faceplate which is laterally spaced from the axis about which the faceplate may pivot relative to the shell in a direction away from the wearer's face.
20. A respirator mask according to any of claims 17 to 19 wherein the harness is made from a non-extensible material so that the outer faceplate and the rigid shell attached thereto remains at a fixed distance from the helmet and the wearer's face. - 19
21. A respirator mask according to any preceding claim wherein the faceplate includes a peripheral edge which is attached to the opening in the front of a protective hood so that the wearer's head is enclosed within the hood.

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22. A respirator mask according to claim 21, wherein the hood is made from a NBC (Nuclear, Biological, Chemical) resistant material.
23. A respirator according to claim 21 or claim 22, wherein the hood includes means, in a region adjacent to where it joins the peripheral edge of the faceplate, to allow the faceplate to pivot relative to the shell.
24. A respirator according to any preceding claim wherein the oro-nasal mask includes extendable means adjacent the peripheral edge thereof and within the rigid shell, and a source of pressurised breathable gas conuccted to the interior of the t5 mask controlled by a regulator which supplied gas at a pressure proportional to G- forces that it is subjected to, operable to expand the extendible means when pressurised gas is supplied to the interior of the mask to press the periphery of the mask towards the wearer's face and improve the seal therewith.
25. A respirator according to claim 24 wherein the extendable means in the bottom portion of the mask are configured to extend more than the extendable means in the top portion of the mask so that when the extendable means are caused to expand by the supply of pressurised breathable gas, the bottom of the mask is moved away from the wearer's face by a greater amount than the top portion, thereby pivoting the mask upwards about a pivot point at which the respirator is attached to a wearer's helmet.
26. A respirator mask according to any preceding claim wherein the flexible oro- nasal mask is made from a natural or synthetic rubber material.
27. A respirator mask substantially as hereinbefore described with reference to the accompanying drawings.