Patent Application
20080178884
The invention generally relates to respirator masks and, more particularly, the invention relates to respirator masks and their associated valves.
Air filtration masks or filter masks are widely used to protect people from air borne contaminants. For example, air borne dust particles are a commonly known hazard at a variety of different types of work sites. Consequently, workers at such sites often wear filter masks to minimize the inhalation of hazardous dust particles. Various types of filter masks are manufactured from a filtering material that filters contaminants from inhaled air. One problem with such filter masks, however, is that the filter material creates an air resistance that increases breathing pressure and makes breathing more difficult. To at least partially alleviate this problem, some filter masks include a one-way valve that opens when the wearer exhales to permit the wearer to exhale more easily and also to expel uncomfortable moist air from the inside of the mask. When the wearer is not exhaling, the valve should remain closed. In fact, this is preferred for all physical orientations of the mask. For example, if the valve is not normally biased closed by some force other than gravity, then it may open when the wearer bends over or otherwise causes the force of gravity to urge the valve open. Under such conditions, a filter mask would not provide the intended air filtering benefits.
Respirator masks and filters used for protection against hazardous environmental substances are generally certified by NIOSH (National Institute for Occupational Safety and Health,) a division of the CDC (Centers for Disease Control & Prevention,) a United States government agency, under the regulations and requirements of 42 CRF Part 84. Under this regulation, particulate filters for air-purifying respirators are tested under a strict protocol not only for filter efficiency but also for inhalation and exhalation breathing resistance, which have specified limits, as detailed in 42 CFR Part 84, Subsection 84.180, and for valve design and function, which must meet the minimum requirements of Subpart 84.177. From the perspective of the user of a mask or respirator, the lower the exhalation breathing resistance as tested by the NIOSH protocol, generally the less breathing strain will be felt in using the respirator and the more comfortable the respirator will be to wear.
The art has responded to this problem by providing filter masks with one-way valves that typically are biased closed in all physical orientations. The way in which the valve is biased closed, however, varies from valve to valve. Some require extra parts, which increases the complexity and thus, the overall cost of the valve. In addition, the biasing may increase the “cracking” pressure of the valve, i.e., the minimum air pressure needed to open the valve, thus potentially making breathing less comfortable for the wearer.
In accordance with one embodiment of the invention, a fluid valve includes a valve base having a central portion with a post and an outer portion having a seat. The fluid valve also includes a diaphragm having a central portion with an opening for receiving the post of the valve base, the diaphragm having a diameter of at least about 1.375 inches, and a cover having a retainer for securing the diaphragm to the valve base at the central portion of the valve base.
In related embodiments, the diaphragm may include a gum rubber having a Shore A durometer ranging from about 35 to about 45 and having a thickness of about 0.015 inches to about 0.025 inches. The diaphragm may be circular in shape. The cover may include an open portion with openings and a closed portion. The post may be cylindrical in shape. The valve base may further include a plurality of flexible ribs between the central portion and the outer portion. The flexible ribs may have a thickness of about 0.035 inches to about 0.045 inches. The flexible ribs may be made from a material comprising polypropylene. The seat may be in a single plane.
In accordance with another embodiment of the invention, a filter mask includes a filter layer having an opening and a fluid valve coupled to the filter layer at the location of the opening. The fluid valve includes a valve base having a central portion with a post and an outer portion having a seat, a diaphragm having a central portion with an opening for receiving the post of the valve base, the diaphragm having a diameter of at least about 1.375 inches, and a cover having a retainer for securing the diaphragm to the valve base at the central portion of the valve base.
In related embodiments, the diaphragm may include a gum rubber having a Shore A durometer ranging from about 35 to about 45 and having a thickness of about 0.015 inches to about 0.025 inches. The diaphragm may be circular in shape. The cover may include an open portion with openings and a closed portion. The post may be cylindrical in shape. The valve base may further include a plurality of flexible ribs between the central portion and the outer portion. The flexible ribs may have a thickness of about 0.035 inches to about 0.045 inches. The flexible ribs may be made from a material comprising polypropylene. The seat may be in a single plane. The fluid valve may be coupled to the filter layer using an adhesive or an ultrasonic means.
In accordance with another embodiment of the invention, a method of making a fluid valve includes providing a valve base having a central portion with a post and an outer portion having a seat. A diaphragm is provided having a central portion with an opening for receiving the post of the valve base, the diaphragm having a diameter of at least about 1.375 inches. The diaphragm is secured to the valve base at the central portion of the valve base with a retainer.
In related embodiments, the diaphragm may include a gum rubber having a Shore A durometer ranging from about 35 to about 45 and having a thickness of about 0.015 inches to about 0.025 inches. The diaphragm may be circular in shape. The valve base may further include a plurality of flexible ribs between the central portion and the outer portion. The flexible ribs may have a thickness of about 0.035 inches to about 0.045 inches. The flexible ribs may be made from a material comprising polypropylene.
In accordance with another embodiment of the invention, a fluid valve includes a valve base having a central portion with a post, an outer portion having a seat, and a plurality of flexible ribs between the central portion and the outer portion. The fluid valve also includes a diaphragm having a central portion with an opening for receiving the post of the valve base, and a cover having a retainer for securing the diaphragm to the valve base at the central portion of the valve base.
In related embodiments, the diaphragm may include a gum rubber having a Shore A durometer ranging from about 35 to about 45 and having a thickness of about 0.015 inches to about 0.025 inches. The diaphragm may be circular in shape. The flexible ribs may have a thickness of about 0.035 inches to about 0.045 inches. The flexible ribs may be made from a material comprising polypropylene. The seat may be in a single plane.
In accordance with another embodiment of the invention, a method of making a fluid valve includes providing a valve base having a central portion with a post, an outer portion having a seat, and a plurality of flexible ribs between the central portion and the outer portion. A diaphragm is provided having a central portion with an opening for receiving the post of the valve base. The diaphragm is secured to the valve base at the central portion of the valve base with a retainer.
In related embodiments, the diaphragm may include a gum rubber having a Shore A durometer ranging from about 35 to about 45 and having a thickness of about 0.015 inches to about 0.025 inches. The diaphragm may be circular in shape. The flexible ribs may have a thickness of about 0.035 inches to about 0.045 inches. The flexible ribs may be made from a material comprising polypropylene. The seat may be in a single plane.
In accordance with another embodiment of the invention, a center post fluid valve includes a valve base having a central portion with a post and an outer portion having a seat, a flexible diaphragm having a central portion with an opening for receiving the post of the valve base, the diaphragm having a diameter of at least about 1.375 inches, and a cover having a retainer for sealingly engaging the flexible diaphragm to the seat.
In related embodiments, the cover may be secured to the valve base near the outer portion using a snap fit, a barb or a press fit.
The foregoing and advantages of the invention will be appreciated more fully from the following further description thereof with reference to the accompanying drawings wherein:
Various embodiments of the present invention relate to a one-way fluid valve and a filter mask with a fluid valve. The one-way fluid valve allows a user to breathe more freely and is designed to remain closed in all orientations when the user is not exhaling. The valve has a valve base, a diaphragm adjacent to the valve base, and a valve cover that covers the diaphragm and secures the diaphragm to the valve base. The valve base and valve cover, together, bias the diaphragm so that the valve remains closed when the user is not exhaling. Details of illustrative embodiments are discussed below.
Various embodiments of the valve and components thereof are sometimes shown or described herein using words of orientation such as “top,” “bottom,” or “side.” These and similar terms are merely employed for convenience and refer to one view of the valve, e.g., as seen on a filter mask, such as shown in
The straps 16 may be constructed from an elastic material, or other conventionally known material that permits a secure and snug fit between the user's face and the mask 10. It is preferred that outer portion of the mask 10 or the rim 18 have a contoured surface that conforms to the user's face. Accordingly, when the straps 16 are pulled and the mask is tightened on the user's face, the contoured surface should be sufficiently flexible and resilient to shape to the user's face. This allows the substantial majority of the user's air to be inhaled and exhaled through the filter mask 10. The outer portion of the mask 10 or the rim 18 may also include additional material, e.g., rubber, to provide an effective seal against the user's face. Although a filter mask has been discussed and shown in connection with
The flexible ribs 34 are provided with a slight pitch such that the inner portions of the ribs 34 near the post 32 are slightly higher compared to the outer portions of the ribs 34 near the seat 36, as seen from the perspective of
As shown in
The diaphragm 40 has a central portion with an opening 42 for receiving the post 32 of the valve base 30. When coupled with the valve base 30, the post 32 extends through the opening 42. The bottom face of the diaphragm 40 thus rests on, or contacts, the seat 36 and may contact the central portion of the valve base 30 near the bottom of the post 32. The opening 42 in the diaphragm 40 may be circular in shape, as shown, or may be any shape that generally corresponds to the shape of the post 32. For example, if the post 34 is rectangular in shape, then the opening 42 may be rectangular or square-like in shape, or even circular, depending on the dimensions of the post 34. The diaphragm 40 may also be circular in shape, as shown, or may be any shape that generally corresponds to the shape of the seat 36.
The diaphragm 40 is made from a flexible, elastic material which allows the valve 20 to remain closed when the user is inhaling and permits the valve 20 to open when the user is exhaling. For example, the diaphragm may be made from a gum rubber having a thickness of about 0.015 inches to about 0.025 inches and having a Shore A durometer ranging from about 35 to about 45. As a result of the center post 32 and the flexible nature of the ribs 34, the diameter of the diaphragm 40 may be larger than prior art center post valves known to the inventors, the larger diameter thus allowing lower cracking pressures to open the valve 20. Consequently, the valve 20 should open more readily when the user exhales. The diameter of the diaphragm 40 is preferably greater than or equal to about 1.375 inches.
The valve cover 50 has a retainer 52 in its central portion for securing the diaphragm 40 to the valve base 30 at the central portion of the valve base 30. Referring also to
The valve cover 50 also includes openings 54 that permit air passage during exhalation. As shown, the location of the openings 54 may be around the outer portion of the cover 50, although other locations may be used. The openings 54 may be provided in part of the cover 50, as shown, or may be provided around the entire cover 50.
The valve cover 50 may also include slots 56 or openings in its sides for securing the valve base 30 to the valve cover 50 in the assembled valve 20. As seen in
The bending or flexing of the flexible ribs 34 allows the retainer 52 and the valve base 30 to properly engage to produce a functional valve 20. The problem with a rigid base coupled with a rigid retainer is that molding tolerance variations may result in a variation in the force that the diaphragm exerts on the valve seat, potentially causing significant variations in the cracking pressure. For example, if the molding variation resulted in a retainer that was too long for a given post height, than the retainer would press down on the valve base with too much force, distorting the diaphragm and preventing a proper seal or, on the other hand, increasing the breathing resistance required to open the valve, thereby making the mask less comfortable to use. The flexible nature of the ribs 34, however, permits wider variations in dimensional tolerances, thus allowing increased manufacturability of the valve 20. By having only the one rigid component, the retainer 52, that mates with the flexible ribs 34, the tolerance variations may be reduced by 50% and the “cracking” pressure may be more precisely controlled. Thus, a lower limit cracking pressure may be realized for any given diameter valve.
During use, the diaphragm 40 remains substantially in contact with the seat 36 when the valve 20 is in the closed position, as seen in
To further illustrate embodiments of the present invention, the following Examples are provided, but the present invention is not to be construed as being limited thereto. In the Examples, the minimum cracking pressure was measured in accordance with the test, requirements of 42 CFR Part 84, section 184.180, at the specified protocol airflow of 85 liters/minute. All of the valves tested had a center post valve configuration.
By contrast, a diaphragm of 1.375 inch diameter in a center post valve having flexible ribs was tested by NIOSH and exhibited a minimum cracking pressure of 4.3 mm H2O and a maximum exhalation pressure of 8.1 mm H2O, with a mean average of 6.2 mm, pressures which are significantly lower than that possible in other prior art center post valves known to the inventors.
Although the above discussion discloses various exemplary embodiments of the invention, it should be apparent to those skilled in the art that variations and modifications may achieve some of the advantages of the invention without departing from the true scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
