Respirator having an integrated oronasal mask

Abstract

A respirator comprising an outer mask in which is defined a main volume and an oronasal mask located within the outer mask and defining a secondary volume. Air for breathing enters the mask via a one-way valve and filter. Exhaled air exits the mask via an exhale conduit fitted with an exhale valve. A conduit is provided for the passage of air from the outer mask to the oronasal mask. The conduit is fitted with a one-way valve and a filter. The filter is such as to filter either particular or vapor challenges, or a mixture of these, as required.

Claims

1. A respirator comprising: an outer mask defining a first volume; an oronasal mask defining a second volume, the oronasal mask being positioned within the first volume; a conduit positioned within the first volume, the conduit having a first end and second end distal the first end, the first end of the conduit being in communication with the first volume and allowing air to flow from the first volume into the conduit, the second end of the conduit including a one-way valve that allows air to flow out of the conduit and into the second volume, at least a portion of the conduit being positioned below the oronasal mask; a primary filter affixed to the outer mask; and a secondary filter located within the conduit and within the portion of the conduit below the oronasal mask.

2. The respirator of claim 1, wherein the secondary filter is removable from the conduit.

3. The respirator of claim 1, wherein the primary filter is physically separate from the secondary filter.

4. The respirator of claim 3, wherein the conduit defines an inner volume and the secondary filter is positioned within the inner volume to filter air that is not filtered by the primary filter.

5. The respirator of claim 1, wherein the conduit is curved.

6. The respirator of claim 1, wherein the outer mask includes a visor, and wherein the first end of the conduit is positioned within the first volume to allow the air to flow across the visor.

7. The respirator of claim 6, wherein the conduit is positioned within the first volume to block the air from taking a route below the oronasal mask that is outside of the conduit.

8. The respirator of claim 1, further including: a flange formed on the second end of the conduit; and an annular groove formed in the oronasal mask; wherein the flange is configured to operate in association with the annular groove to mount the conduit below the oronasal mask.

9. A respirator comprising: an outer mask defining a first volume; an oronasal mask defining a second volume, the oronasal mask being positioned within the first volume; a removable conduit positioned within the first volume, the removable conduit having a first end and second end distal the first end, the first end of the removable conduit being in communication with the first volume and allowing air to flow from the first volume into the removable conduit, the second end of the removable conduit including a one-way valve that allows air to flow out of the removable conduit and into the second volume, at least a portion of the removable conduit being positioned below the oronasal mask; a primary filter affixed to the outer mask; and a secondary filter located within the removable conduit and within the portion of the removable conduit below the oronasal mask.

10. The respirator of claim 9, wherein the primary filter is physically separate from the secondary filter.

11. The respirator of claim 10, wherein the removable conduit defines an inner volume and the secondary filter is positioned within the inner volume to filter air that is not filtered by the primary filter.

12. The respirator of claim 9, wherein the removable conduit is curved.

13. The respirator of claim 9, further including: a flange formed on the second end of the removable conduit; and an annular groove formed in the oronasal mask; wherein the flange is configured to operate in association with the annular groove to mount the removable conduit below the oronasal mask.

14. A respirator comprising: an outer mask defining a first volume, the outer mask having a visor; an oronasal mask defining a second volume, the oronasal mask being positioned within the first volume; a conduit positioned within the first volume, the conduit having a first end and second end distal the first end, the first end of the conduit being in communication with the first volume and the second end including a one-way valve and being coupled to the oronasal mask, the conduit arranged to allow air to flow across the visor and from the first volume into the second volume, at least a portion of the conduit being positioned below the oronasal mask; a primary filter affixed to the outer mask; and a secondary filter located within the conduit and within the portion of the conduit below the oronasal mask.

15. The respirator of claim 14, wherein the conduit defines an inner volume and the secondary filter is positioned within the inner volume to filter air that is not filtered by the primary filter.

16. The respirator of claim 15, wherein the first end of the conduit is positioned within the first volume to allow the air to flow across the visor.

17. The respirator of claim 14, further including: a flange formed on the second end of the conduit; and an annular groove formed in the oronasal mask; wherein the flange is configured to operate in association with the annular groove to mount the conduit below the oronasal mask.

Description

(1) In order that the invention may be better understood, an embodiment thereof will now be described by way of example only and with reference to the accompanying drawings in which:

(2) FIG. 1 is a diagrammatic view of a respirator in the form of a full-face mask, intended to illustrate the principles of the invention;

(3) FIG. 2 is an exploded perspective view of one embodiment of a respirator, in the form of a full-face mask, constructed in accordance with the invention;

(4) FIG. 3 is a view looking into the interior of the mask of FIG. 2;

(5) FIG. 4 is a view similar to FIG. 3, but in which the outer parts of the mask are shown dotted in order to reveal some features of the mask interior not clearly visible in FIG. 3;

(6) FIG. 5 is a front view of the oronasal mask and attached filter assembly, as fitted to the mask of FIG. 2; and

(7) FIG. 6 is a perspective view from the rear and above of the filter assembly fitted to the oronasal mask of FIG. 5.

(8) Reference is firstly made to FIG. 1 which is a diagram to illustrate the principles of the invention. The respirator is represented as a full face mask 1 comprising an outer mask 2 intended to seal around the perimeter of a wearer's face and having a transparent visor whose position is represented by the dotted outline 3. An oronasal mask 4 is located within the outer mask 2 and is equipped with a conventional exhale conduit 5 fitted with an exhale valve 6. The valve 6 is such as to allow exhaled gas to exit from the oronasal mask to the exterior, but to prevent potentially contaminated air from the outside from passing into the mask.

(9) Air 7 for breathing enters the outer mask 2 via an inlet port 8 fitted with a one-way valve 9 and a filter 10. The filter 10 contains one or more filter elements designed to filter either particulate or vapour challenges from the incoming air, or a mixture of these, as required.

(10) The incoming air passes preferentially across the upper part of the outer mask, across the visor, as represented by the arrows 7. The air then enters the input of a conduit 11 by which the air is passed back in a direction towards the input port 8, and enters the oronasal mask 4 via a one-way valve 12.

(11) Mounted within the conduit 11 is a secondary filter 13 which filters the incoming air as it passes into the oronasal mask 4. The filter 13 may be such as to filter either particulate or vapour challenges, or a mixture of these, as required.

(12) When in use, the outer mask 2 and oronasal mask 4 bear against the wearer's face by means of respective seals 14, 15 made of elastomeric material. It will be noted that the two seals are independent of one another, the oronasal seal 15 being contained wholly within the outer mask seal 14. This is the preferred form but, in another variant, the outer mask is compartmentalised to form the oronasal mask with the oronasal mask sharing some of its seal with that of the outer mask. This variant is less desirable however since it means that isolation of the oronasal mask from the ambient air is compromised.

(13) In the embodiment illustrated, the seals 14, 15 define, with the face, two separate volumes, referred to as the main volume 16 and the oronasal volume 17 respectively. The oronasal volume 17 is located wholly within the main volume 16 and is sealed therefrom, which means that the oronasal volume is doubly isolated from the ambient air. Leaving aside possible leakages of the seal 15, air can pass from the main volume 16 to the oronasal volume 17 only via the conduit 11, where it is filtered by secondary filter 13. Likewise leaving aside possible leakage of the seal 14, air can pass from the exterior to the main volume 16 only via the filter 10. The secondary filter 13 can thus be said to augment the filter 10, or primary filter, by being, in effect, connected in series with it. This assumes however that the seals, particularly the outer seal 14, are 100% effective which is unlikely to be the case; in practice air will leak across the outer seal 14, particularly during inhalation when there will be a slight negative, pressure within the main volume 16 which will tend to draw air in. Thus, in practice, the air passing through the secondary filter 13, whilst comprising mainly air which has been filtered by filter 10, will also comprise a small proportion of potentially contaminated air which has leaked in across outer seal 14 and has thus not been filtered.

(14) It will be noted that the provision of a completely separate oronasal volume within the main volume maximises the wearer's protection against small amounts of contaminated air in the main volume since such contaminated air still has to pass across the oronasal seal 15 before it can become a danger to the wearer.

(15) Air for breathing is drawn into the mask by the action of the wearer inhaling which causes a pressure drop in the oronasal mask and draws air in through the filter conduit 11 and ultimately through the inlet port 8 via filter 10. In so doing, the incoming air passes across the visor 3, thus helping to demist the visor. The moisture-laden exhaled air does not enter the main volume 16 (except by leakage across seal 15) and exits directly to the exterior via the conduit 5.

(16) A practical embodiment of the invention, utilising the principles explained with reference to FIG. 1, will now be described with reference to FIGS. 2 to 6. Where appropriate, the same reference numerals have been used for the corresponding parts.

(17) FIGS. 2 to 6 show a respirator in the form of a full face mask 1 comprising an outer mask 2 having a transparent visor 3, and an oronasal mask 4. Fitted below the oronasal mask 4 is a filter conduit 11, housing the secondary filter (not visible), and the assembly of the oronasal mask 4 and conduit 11 are fitted within the outer mask 2 by a front fitting comprising a cylindrical exhale cartridge housing 20 and corresponding cylindrical locknut 21 which screw together through a front aperture 22 in the outer mask 2. The oronasal mask 4 has a corresponding front aperture 23 which is sealingly fitted over a flange 24 on the housing 20. An optional coarse mesh filter 25 may be fitted within the housing 20, this being to prevent liquid or mucus ejected by the wearer from clogging the exhale valve. The exhale valve 6 is located in a cylindrical housing 26 which is detachably fitted to the front of the housing 20. A louvred cover 27 is fitted to the housing 26 to define a dead space downstream of the exhale valve to prevent lifting of the valve in certain adverse conditions.

(18) Thus it will be seen that an exhale path is defined from the interior of the oronasal mask 4 direct to the exterior without entering the main volume defined by the outer mask 2.

(19) The mask is held on the wearer's head by means of straps (not shown) which engage with buckles 28 mounted on short straps 29 of elastomeric material attached to the outer mask 2. These fittings are conventional and will not be described further.

(20) The outer mask 2 seals against the perimeter of the wearer's face by means of a flexible seal 14 made of elastomeric material. The purpose of this seal is to create within the outer mask 2 a main volume 16 of air which is as airtight as possible. However, it is impossible to design a seal which will provide a 100% effective seal against all shapes of face and in all circumstances, so potential leakage of this seal has to be catered for. In the present mask, this is addressed by defining, within the main seal 14, a secondary seal 15 by which the oronasal mask 4 is sealed against the wearer's face. Thus contaminated air in the ambient atmosphere has to jump both seals before it can become a danger to the wearer. The shape and position of seals 14 and 15 is clearly shown in FIG. 3, which is a view looking into the interior of the mask.

(21) Air to be inhaled is drawn into the mask by the action of the wearer inhaling which causes negative pressure to be created within the oronasal mask, and hence within the main volume 16 of the outer mask, as described previously. This in turn draws air in through an inlet port in the form of an inlet valve housing 30 which is screwed through a side aperture 31 in the outer mask 2 and retained with a nut 32 and washer 33. A flap valve 34 is mounted within the housing 30 to create the aforesaid one-way inlet valve 9. The housing 30 is equipped with a fitting 35 suitable to removably attach a cartridge-type filter (not shown).

(22) Particular reference is now made to FIGS. 5 and 6 which illustrate the oronasal mask 4 and secondary filter conduit 11. The conduit 11 has a generally curved shape defining, at one end, an inlet 40 for incoming air and, at the other end, an outlet 41 for air entering the oronasal mask. The outlet 41 is formed with a flange 42 whereby, in association with a corresponding annular groove 47 formed in the oronasal mask 4, the conduit 11 may be physically mounted underneath the oronasal mask to form the assembly illustrated in FIG. 5.

(23) The outlet 41 is also formed with an open framework 43, on which is mounted through a central aperture a flap valve element 44 made of elastomeric material such as silicone rubber or butyle rubber. The arrangement is such that, in its normal position, the valve element seals the outlet 41 by resting against a slightly raised annular rim 45 but will flap open if air is drawn into the conduit 11 through its inlet 40. Thus the element 44 forms, with the associated structure, the aforesaid one-way flap valve 7, allowing air to flow through the outlet 41 and into the oronasal volume 17, but not in the reverse direction. The one-way exhale valve 6 and inlet valve 9 are constructed in a similar way.

(24) Situated within the conduit 11 is a filter positioned to filter all air passing from the inlet 40 to the outlet 41 of the conduit. The nature of this filter has already been discussed. The filter element or elements may be removable but, more likely, the whole conduit 11 will be replaced when the filter needs changing.

(25) Particular reference is now made to FIG. 4 which shows the same view as FIG. 3, but in which the outer mask 2 is shown in dotted outline, enabling more of the interior detail to be visible. Input air enters through the main filter (not shown) through the cylindrical housing 30 containing one-way valve 9 and into the interior of the outer mask 2. Immediately opposite the exit to the housing 30 is the upstanding part 46 of the conduit 11 (FIG. 5) which leads to the outlet 41; however, the inlet air cannot enter the conduit 11 at this point and is instead directed across the main volume 16 of the outer mask to enter the conduit at the inlet 40 situated on the right-hand side (when seen in FIG. 4). It will be seen that the arrangement of the oronasal mask 4 and conduit 11 within the main volume 16 is such that the incoming air, in passing from the left side to the right side of the main volume, when seen in FIG. 3, preferentially flows across the top of the oronasal mask, and thus across the visor 3, instead of taking a route beneath the oronasal mask 4 which is substantially blocked by the presence of the conduit 11. For this purpose the conduit 11 and inner surface of the outer mask 2 in this area are given an approximately corresponding shape to enhance this effect. As already explained, this flow of air across the mask effectively demists the visor.

(26) Other details of the operation of the mask described with reference to FIGS. 2 to 6 will not be repeated because it will be readily understood with reference to the description of FIG. 1, already given.