This invention relates generally to a wearable protective device and, more particularly but not necessarily exclusively, to a facial breathing mask incorporating an exhalation valve, and a removable cover for such an exhalation valve.

Many different types of facial breathing mask are known for protecting a wearer against breathing in dangerous fumes, preventing cross -infection and the like. One such known mask comprises a resiliency flexible, e.g. rubberised, mask body configured to fit over a user's nose and mouth, in use, and including a generally central opening, in which is provided an opening defining an airway and having provided therein a set of radial support members, over which is provided a flexible diaphragm configured to define a one-way exhalation valve. The mask body is further provided with a pair of openings at opposing sides or 'cheek' portions thereof, for receiving respective filter cartridges. In use, when a user inhales, the diaphragm seals the central opening and the inhaled air is forced to pass through the filter cartridges to the user's nose and mouth. When the user exhales, the force of the airflow causes the edges of the diaphragm to flex away from the central opening support members, allowing exhaled air to pass therethrough out of the mask.

It is necessary to provide a cover on the protective device, over the diaphragm forming the exhalation valve, to prevent it from becoming damaged and/or clogged up with debris, for example. However, it is equally important to allow periodic access to and removal of the diaphragm such that it, and the corresponding exhalation airway components, can be cleaned and then reassembled for further use. Thus, a removable cover is generally provided for this purpose.

In prior art devices, such a removable cover is generally configured to clip on and off the face mask (in a linear direction). However, in view of the flexible nature of the mask body, and the degree of deformation that may occur when a user is securing the mask over their face, the valve cover can, relatively easily, be dislodged and inadvertently removed.

It would, therefore, be desirable to provide a wearable protective device including an exhalation valve, in which a removable cover is provided which addresses this issue.

In accordance with an aspect of the present invention, there is provided an exhalation valve assembly for a wearable protective device, said assembly comprising a valve support for receiving a valve member, in use, a valve cover and a releasable mounting mechanism for releasably mounting said valve cover to said valve support so as to substantially cover said valve member, said mounting mechanism comprising a bayonet locking mechanism having a first part located on said valve support and a second part located on said valve cover, said first and second part being configured to engage in a locked configuration when said valve cover is rotated, in use, relative to said valve support from an unlocked configuration.

The mounting mechanism may comprise at least two spaced apart locking members on said valve support, each locking member defining a locking edge, and at least two spaced apart openings in said valve cover, the location of said openings corresponding substantially to the location on said valve support of said locking members when said valve cover is located thereon so as to substantially cover said valve member such that the locking edge of each locking member engages with a locking edge of a respective opening in said valve cover, said first part of said bayonet locking mechanism being provided on each said locking member locking edge and said second part of said bayonet locking mechanism being provided on each said valve cover opening locking edge.

The locking members may be located adjacent substantially diametrically opposing edges of said valve support and said valve cover openings are located adjacent corresponding substantially diametrically opposing edges of said valve cover.

In one exemplary embodiment, the valve cover may comprise an open ended receptacle having side walls defining an enclosure and a cover at one end thereof, wherein said valve cover openings extend over at least 50% of the axial length of said side walls.

The valve cover openings may extend over between 50 and 75% of the axial length of said side walls. In an alternative exemplary embodiment, the valve cover openings may extend over more than 75% of the axial length of said side walls.

The mounting mechanism may comprise at least a third locking member on said valve support defining a locking edge and including a first part of said bayonet locking mechanism, and at least a third opening in said valve cover defining a locking edge and including a second part of said bayonet locking mechanism.

The first part of said bayonet locking mechanism may comprise a notch located along the length of the locking edge of each said locking member, and said second part of said bayonet locking mechanism may comprise a projection located along the length of the locking edge of each said opening in said valve cover. However, in other exemplary embodiments, it is envisaged that the notch may be provided on the locking edge of the valve cover openings, and the projection may be provided on the locking edge of the locking members.

Either way, the inner edge of each said notch may be stepped or relatively steeply tapered, and said locking edge on at least one side of said notch is provided with a relatively shallowly tapered profile. The locking edge on at least one side of said notch may have a substantially convex curved profile along the direction of travel of said valve cover relative to said valve support during rotation thereof from said unlocked configuration to said locked configuration, in use. The valve cover may comprise two outer cover sections, a first, raised cover section and a second, lower cover section, said first and second cover sections defining a vertical through-hole therebetween.

Aspects of the present invention extend to a respiratory facial breathing mask including an exhalation valve assembly substantially as described above. These and other aspects of the present invention will become apparent from the following specific description, in which embodiments of the present invention are described, by way of examples only, and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an exhalation valve and cover according to an exemplary embodiment of the present invention; Figure 2 is an exploded perspective view of a respiratory face mask incorporating the exhalation valve and cover of Figure 1 ;

Figure 3 is a schematic front view of the respiratory face mask of Figure 2, in its fully assembled configuration, but with the cover removed;

Figure 3 a is a schematic side view of the respiratory face mask of Figure 3; Figure 3b is a schematic partial front view of a portion of the locking mechanism used in the exhalation valve of Figure 1 ;

Figure 3c is a schematic partial side view of a portion of the locking mechanism used in the exhalation valve of Figure 1 ; Figure 4 is a front view of the respiratory face mask of Figure 2 in its fully assembled configuration, including the cover in its unlocked configuration;

Figure 5 is a front view of the respiratory face mask of Figure 4, with the cover in its locked configuration; Figure 6 is a partial side view of an exhalation valve according to an exemplary embodiment of the present invention, with the cover in its unlocked configuration; and

Figure 7 is a partial side view of the exhalation valve of Figure 6, with the cover in its locked configuration.

Referring to Figure 2 of the drawings, a respiratory mask including an exhalation valve according to an exemplary embodiment of the present invention comprises a rubberised mask body 6, a rigid inner body 1, a strap ring 2, a diaphragm 3 and an exhalation valve cage (or cover) 4. Each of these elements fits together to form a complete respiratory mask having side openings 36a for receiving a respective disposable filter cartridge (not shown). In its assembled form, the inner body 1 is sealed and affixed within the mask body 6, but the strap ring 2, diaphragm 3 and valve cover 4 can all be removed and re-attached as required.

Referring to Figure 3 of the drawings, there is provided a generally central, substantially circular opening 6a on a front face 6b of the mask body 6, the mask body 6 being formed of an elastically deformable material, e.g. rubber or the like. The inner body 1 defines a substantially rigid plate la defining a generally central, substantially circular collar lb that projects outwardly from the opening 6a in the mask body 6. The collar lb is spanned by six substantially equi- angularly spaced support struts 8 which extend, substantially radially, from a generally central pin hole 9. A pair of openings are provided on opposing sides of the mask body 6 and configured to removably receive respective disposable filter cartridges of any known configuration.

Referring back to Figure 2 of the drawings, a flexible diaphragm 3 is provided over the opening defined by the collar lb and is supported by the struts 8, and secured by a rearwardly projecting pin which is integrally formed with the diaphragm 3 and configured to be received within the pin hole 9. Referring additionally to Figures 3a to 3c of the drawings, three generally L-shaped locking members 110 are integrally formed with the inner body and located adjacent to the circumferential edge of the collar lb. Each locking member 110 comprises an elongate leg portion 110a and a shorter flange portion 110b at its distal end which extends substantially orthogonally to the longitudinal axis of the leg portion 110a to create the substantially reshaped locking member 110. Each locking member 110 extends, from the proximal end of the respective leg portion 110a, outwardly and at a slight angle to the front face of rigid plate la, and the flange portion of 110b of each locking member 110 extends radially outward relative to the opening 6a and substantially parallel to the principal plane of the rigid plate la, as shown most clearly in Figure 3b of the drawings.

As shown particularly in Figure 3c of the drawings, the free edge of the flange portion 110b of each locking member 110 is profiled to include a notch 110c at an intermediate distance along its lateral length. The notch 110c is defined by stepped or sharply tapered inner edges and a curved and convex profile leading to a shallower taper at a location laterally distant from the notch 110c.

Referring back to Figure 2 of the drawings, the strap ring 2 defines a generally central recess 2a defining an opening 2b, that accommodates the collar lb of the inner body 1, over which the diaphragm 3 is mounted, when the respiratory mask is fully assembled for use. The opening 2b is framed by a substantially circular border 2c defining the inner

circumferential edge of the recess 2a. The valve cage or cover 4 comprises a generally cylindrical, substantially rigid shell 4a, which may be transparent and formed of, for example, plastics material. The cylindrical shell is circumferentially dimensioned to fit within the recess 2a of the strap ring 2 when the respiratory mask is fully assembled for use. The shell is provided with an outer cover having a first, raised convex portion 4b and a second, lower substantially flat portion 4c, defining a generally central upper opening 4d therebetween. A vertical support member 4e is provided vertically across the opening 4d between the raised and lower cover portions 4b, 4c. The side edges of the shell 4a are provided with cut-away portions in the form of substantially rectangular openings 20a, 20b, 20c which extend laterally from the outer edge of a respective cover portion and a location close to the opposite longitudinal edge of the shell 4a, i.e. close to the circumferential edge of the strap ring recess 2a when the respiratory mask is fully assembled for use, and spanning almost the entire length of the cylindrical shell portion 4a of the cover. The lower edge of each of the rectangular openings 20a, 20b, 20c is provided with a respective tooth or rib 13 at a location that is off-centre along its length.

It will be appreciated from, for example, Figures 1, 4, 6 and 7 of the drawings, that the relative locations of the openings 20a, 20b, 20c in the shell of the valve cage or cover 4 correspond generally to the relative locations of the locking members 110 provided on the inner body 1 and the circumference of the shell 4a, at least at the location of the openings 20a, 20b, 20c is such that the locking members 110 can be accommodated within the shell at these respective locations when the respiratory mask is fully assembled for use.

Further openings 22 may be provided at the circumferential locations around the side of the shell 4a, as required, to further decrease breathing resistance, as will be discussed in more detail later.

In use, the valve cage 4 can be placed over the exhalation valve of the respiratory mask (outwardly defined by the diaphragm 3), and twisted relative to the locking members 110 to lock the valve cage (in the form of a cover) over the exhalation valve assembly. The locking mechanism is in the form of a bayonet locking mechanism, with the notch 110c in each of the flange portions 110b of respective locking members 110 forming the female receptor of the locking mechanism and the tooth or rib 13 on the inner edge of each of the openings 20a, 20b, 20c forming the male part of the mechanism.

Thus, referring to Figures 6 and 7 of the drawings, each opening 20a, 20b, 20c has a raised tooth 13 on the innermost edge of the aperture relative to the main body 6 of the respiratory mask, when in a fully assembled configuration for use. The raised tooth 13 of each opening 20a, 20b, 20c corresponds to a notch 110c in the flange portion 110b of each locking member 110.

Referring to Figure 6 of the drawings, when the exhalation valve is in the unlocked configuration, the three locking members 110 are loosely received within the recesses defined by the rectangular openings 20a, 20b, 20c of the valve cage 4. Therefore, the valve cage 4 can be lifted from the assembly, releasing the strap ring 2 and enabling the exhalation valve to be dismantled. This may, for example, be necessary in order to remove and clean the diaphragm 3, a task which generally needs to be performed on a regular basis.

Conversion of the exhalation valve from the unlocked configuration to the locked configuration requires a substantially 45° rotation of the valve cage, forcing the inner edge of the openings 20a, 20b, 20c along the convex and tapered edge of respective flange portions 110b of the locking members 110 until each tooth 13 reaches a respective notch 110c and the stepped, opposite edge of the notch 110c prevents further rotation of the valve cage 4 relative to the inner body without the application of a much larger force.

Referring to Figure 7 of the drawings, when the exhalation valve is in the locked configuration each raised tooth 13 sits inside each notch 110c in each respective flange portion 110b of the locking members 110, preventing the valve cage 4 from rotating and subsequently lifting from the assembly. The shallow taper and curved profile of the leading inner edge of each opening 20a, 20b, 20c (in the direction of travel of the cover when being rotated from the unlocked to the locked configuration) allows the locking action to be effected with relatively little force. However, the steeper, stepped edges immediately adjacent the each notch 110c means that a much greater force is required to unlock the valve cage 4 to remove it, thereby minimising its accidental removal, in use.

The overall configuration of the valve cage locking mechanism, and the use of the large side openings as part of the locking mechanism itself, enables the cover to be provided with a relatively large open area, and breathing resistance is thereby minimised.

In some exemplary embodiments of the invention, and as can be seen in Figure 3 of the drawings, two of the locking members 110, and therefore two of the flange portions 110b are of the same dimensions, whilst a third locking member 110, and therefore the respective third flange portion 110b, is of a different, smaller, dimension. This ensures that the valve cage 4 cannot be assembled onto the respiratory mask incorrectly and the corresponding openings 20a, 20b, 20c will only engage with the flange portions 110b in a single, specific orientation. There are may also be markings engraved on the surface of the strap ring 2, corresponding to an indent in the valve cage 4, directing the user to the correct positions for the valve cage 4 when in the unlocked and locked configurations.

It will be apparent to a person skilled in the art, from the foregoing description, that modifications and variations can be made to the described embodiments without departing from the scope of the invention as defined in the appended claims.