MXPA97005351A - Respirator that has a preset filter cartridge - Google Patents

Abstract

The present invention relates to a respirator, characterized in that it comprises: (a) a facepiece sized to be placed over at least one person's nose and mouth, (b) a cartridge receiving structure located in the facepiece; and (c) a filter cartridge having a housing in which a filter element is contained, the filter cartridge is capable of being manually held in engagement with the cartridge receiving structure to produce an audible noise, the coupling is obtained instantaneously By pressing the filter cartridge against the receiving structure without rotational movement, the filter cartridge is also able to easily separate from the cartridge receiving structure by manually pulling it into the cartridge.

Description

RESPIRATOR HAVING PRESSURE ADJUSTMENT FILTER CARTRIDGE DESCRIPTION OF THE INVENTION This invention pertains to a respirator having a press fit filter cartridge. Many techniques have been used in respirators to couple the filter elements to the respirators. A common technique has the filter element placed in a threaded cartridge which is coupled to a corresponding threaded fitting on the respirator body; see, for example, U.S. Patent Nos. 5,222,488, 5,063,926, 5,036,844, 5,022,901, 4,548,626, and 4,422,861. Known filter cartridges typically have helical threads or progressive coils that engage a tapered collar or plug that receives the threaded portion of the filter cartridge. Rotation of the filter cartridge in an appropriate direction allows the cartridge to be coupled to or removed from the respirator. A flexible, deformable packaging is often used to ensure an air-tight fit to the respirator body. Instead of threads, a bayonet type closure has been used to attach a filter cartridge to a respirator; see, for example, Patents REF: 25112 North American Nos. 5,062,421, 4,934,361, and 4,850,346. The bayonet-type closure described in the M21 patent has securing tabs and slots for securing the components together. The securing tabs project from the filter cartridge and engage the slots in an opening on the respirator body. By rotating the filter cartridge in the proper direction, the cartridge is in engagement. In patents 361 and 346, an audible device is used to indicate that the filter cartridge is properly coupled to the facepiece of the respirator. A leg on the facepiece is provided with a stop ramp or cam having an inclined surface which is positioned to flex or gradually deform a rib on the cartridge. As the cartridge and facepiece are rotated relative to each other to an assurance position, the cam engages the rib and causes the rib and leg to flex until the rib abruptly falls off the end of the cam. The abrupt action produces the audible swoosh. In another technique described in U.S. Patent No. 5,148,803, a bellows is used to secure a respirator filter. The bellows, together with a rigid band, forms a rigid fold that receives the filter. The fold is continued in an elastic jacket that surrounds the filter in a gas-tight manner. To change the filter, the jacket is first folded back to the level of the fold, the filter element is inserted into the fold, and the shirt is then folded back on the filter element. U.S. Patent Nos. 5,033,465 and 5,078, .32 describe a respirator that uses edge seals to secure a filter element to the elastomeric facepiece of the respirator. The filter element includes bonded activated carbon granules, and the edge seals are placed between the filter element and the elastomeric facepiece. The edge seals are made of an appropriate adhesive material, such as a hot melt adhesive, a hot melt foam adhesive, or a latex adhesive. A foam mask shell is described in U.S. Patent No. 4,856,508 for receiving a filter cartridge. The shell of the foam mask has a collar that defines an opening for receiving the filter cartridge. The filter cartridge has an extension with an outer dimension approximately equal to the internal dimension of the cylindrical passage through the collar. To mount the filter cartridge, its extension is inserted into the opening where it performs a friction fit, relatively hermetic. The mask shell is made of a flexible foam material that expands when the extension is inserted into the opening. To replace a filter cartridge, it is held and twisted back and forth while being pulled away from the shell of the mask. In U.S. Patent No. 4,790,306, a respirator using insert molding is described to permanently secure an absorbent filter element attached to a respirator facepiece. A plug frame is disclosed in U.S. Patent No. 4,771,771 to secure a filter cartridge in a respirator chamber. The filter cartridge is placed in the chamber by seals that limit tightly against the cartridge, to hold it in place. The filter cartridge can be adjusted to the respirator by sliding it through an opening in the plug frame. In U.S. Patent No. 4,630,604, securing tabs are employed on a filter retainer to maintain a replaceable filter member in a limiting relationship to the structure of the respirator. The filter member can be replaced by removing the filter retainer member from the structure. An additional technique is disclosed in U.S. Patent No. 4,562,837 where the respirator is provided with a guide ring for engaging a filter housing. The guide ring is carried by a sleeve portion defining an opening through which gases pass. The filter housing slides over the guide ring from a retracted rest position to an extended use position. A bellows, located between the filter housing and the respirator, allows movement of the filter housing between its retracted rest or standby position and its extended use position. Sundstrom Safety AB of Lidingo, Sweden markets a respirator in Europe and Australia under the designation SR-62, which uses a filter holder, made of elastomeric rubber, to accommodate a filter cartridge. The filter cartridge comprises a filter for gas and steam or particulate in a rigid injection molded plastic cartridge. To insert the filter cartridge into the retainer, the retainer is stretched over the periphery of the filter element. When two different filters are used in series, they can be held together and inserted into the retainer as a single unit. To separate the filters, a tool is provided on the harness system to start them. Although the respirators discussed above use various techniques to secure a filter and the filter cartridges to the respirators, these techniques have a number of drawbacks. For example, filter cartridges that are screwed into the respirator typically include a housing or basket within which the filter material is retained. The cylindrical geometry of the cartridge typically requires the use of the filter cartridge as an external appendage that may interfere with a user's vision. In addition, the threaded cartridges employ many parts that are added to the total volume of the filter element, and to the total weight of the respirator. In other designs, such as are described in US Patent Nos. 5,078,132, 5,033,465, and 4,790,306, the filters are not capable of being easily replaced, and thus when the service life of the filter element has reached its limit, the Full respirator is discarded as waste. In the model SR-62 respirator sold by Sundstróm, the filter cartridge is replaceable; however, the retainer lacks physical strength in relation to the filter element, and thus, as a rubber tire is placed on a wheel, a number of manipulations are necessary to place the filter element in the rubber retainer elastomeric In addition, elastomeric materials can be relatively expensive and more difficult to process. Some of the other respirators discussed above have the drawback of using gaskets or rings to obtain an airtight seal or use obviously complicated systems to mount the filter elements to the respirators The respirator of this invention overcomes many of the drawbacks of prior art respirators. The respirator does not use many parts to secure the filter cartridge to the facepiece of the respirator, and there is no need for a package, O-ring, or permanent adhesive to obtain a tight fit between the cartridge and the facepiece. Also, the filter cartridge is of relatively light weight, and can be mounted to and removed from the facepiece in a simple movement without excessive manipulation. The respirator is relatively easy to manufacture, allowing production costs to be minimized. In summary, the respirator of the invention comprises: a) a face piece adjusted to fit at least on the nose and mouth of a person; b) a cartridge receiving structure located on the facepiece; and c) a filter cartridge having a housing within which a filter element is contained, the filter cartridge is capable of being manually held in engagement with the cartridge receiving structure, to produce an audible noise, the coupling being instantaneously obtainable by pressing the filter cartridge against the receiving structure, without rotational movement. The present invention also includes a filter cartridge useful for filtering contaminants that are present in air that is inhaled through a respirator worn by a person. The filter cartridge allows instant coupling and removal of the respirator from a facepiece, and comprises a housing and a filter element. The filter element is contained in the housing, and the housing includes a means for allowing the filter cartridge to be manually placed in engagement with a cartridge receiving structure, by pressing the filter cartridge against the cartridge receiving structure, without using rotational movement. The invention differs from known respirators in that the filter cartridge can be simultaneously attached to the facepiece of the respirator without rotational movement. This is achieved simply by pressing the filter cartridge against the corresponding receiving structure on the facepiece. The invention thus provides an extremely easy means for coupling a filter cartridge to the facepiece of the respirator. An audible noise is provided to indicate a secure coupling. The invention can also allow the filter cartridge to be quickly removed from a respirator facepiece. This can be achieved simply by pulling on the cartridge in a direction opposite to which it was pressed on the facepiece. The rotational movement is also not necessary to separate the filter cartridge from the facepiece of the respirator. In the drawings: The Figure is a perspective view of a respirator 10 according to the invention; Figure 2 is a front view of the respirator 10 according to the invention, without the filter element 16 placed in the cartridge 12.

Figure 3 is a partial cross-sectional view of the respirator 10 taken along lines 3-3 of Figure 2; Figure 4 is an expanded cross-sectional view, illustrating the coupling of the filter cartridge 12 to the facepiece 14, according to the invention.

Figure 5 is a cross section of a filter cartridge 12 according to the invention.

In the practice of this invention, a respirator is provided having a filter cartridge that can be manually coupled to and uncoupled from a facepiece of the respirator, with no risk of leakage. The seal between the cartridge and the facepiece is airtight, and the coupling and decoupling can be instantaneous. Figures 1, 2, and 3 illustrate a respirator 10 comprising a filter cartridge, 12 and a facepiece 14. The filter cartridge 12 includes a cylindrical housing 13 containing a cylindrical filter element 16. The filter element 16 may comprise, as shown, a filter 18 for gases and a filter 20 for particulate materials. The filter element 16 is described in more detail below. The housing 13 of the filter cartridge surrounds the peripheral surface of the filter element and covers its entrance surface at the periphery. The filter cartridge 12 can be put into engagement with the facepiece 14 by the steps consisting essentially of pressing the filter cartridge against the facepiece in a direction generally normal to the facepiece (or parallel to the axis of the facepiece cartridges). filter) . The cartridge can be secured to the facepiece without rotational movement of the cartridge or facepiece - although the invention does not necessarily dictate such movement. The cartridge 12 can be quickly removed from the facepiece by the steps consisting essentially of holding the filter cartridge 12 (including an appendage thereto) and pulling on it axially in a direction away from and normal to the facepiece 14. It is also not necessary to rotational movement to remove the cartridge from the facepiece.

Facepiece 14 is sized to fit at least on a person's nose and mouth. A face piece could be conceivably provided, so that it fits over other portions of a person's face (namely, the eyes), such as in the complete facial configuration; however, the facepiece, as illustrated herein, is typically sized in a half-mask configuration - that is, one that fits only over the nose and mouth. As shown, the facepiece 14 may comprise a soft elastic portion 15, molded in sealing engagement around a rigid central portion 17. The rigid central portion 17 includes an opening 19 through which the filtered air travels to enter the air. inside the respirator. An inhalation valve can be mounted on 21, as desired. Respirators having elastic, soft facial portions, and rigid central sections on which the filter cartridge (s) are mounted, are known in the art as shown in U.S. Patent No. 5,062,421. As shown, the respirator 10 is a "negative pressure" respirator. That is, the ventilator relies on the user's lungs as the means to pull air through the respirator. Such respirators are referred to as "negative pressure" because the pressure inside the respirator is less than the ambient pressure during an inhalation. In contrast, "positive pressure" respirators rely on forced air (for example, coming from a pressure tank or blower that is carried by the person) to supply oxygen to the user, and the pressure inside the respirator is greater than the atmospheric The present invention may also be suitable for use with positive pressure respirators. When the respirator 10 is used, the negative pressure created by the expansion of the user's lungs causes the air to be pulled through the filter element 16 in the cartridge 12, out of an outward flow opening (23, Figures 3 and 4) into the cartridge 12 of filter, and through a flow inlet opening (19, Figures 3 and 4) in the facepiece 14 of the respirator, to enter the interior of the facepiece where the air can be inhaled by the user. In this way, the filter cartridge is placed in fluid communication with the interior of the respirator facepiece. Figures 3 and 4 structurally illustrate how the filter cartridge 12 can be press fit to the facepiece 14. Facepiece 14 does not include a filter element, but includes a cartridge receiving structure in the form of a flange 22 in projection to allow a filter element to be secured to the facepiece 14. As shown, the projecting flange 22 engages a skirt 24 on the filter cartridge 12. The protruding flange 22 preferably has a radially outwardly projecting surface 22, which engages a surface 28 projecting radially inwardly on the skirt 24. When the filter cartridge 12 is pressed axially towards the facepiece 14 , the skirt 24 expands radially outward from its rest position, while the projecting flange 22 is pressed radially inwardly. As the filter cartridge 12 continues to press toward the facepiece 14, the surface 28 projecting radially inwardly passes the maximum point 29 radially outwardly of the surface 26 projecting radially outwardly, allowing the skirt 24 to contract. inward and tab 22 expands outward. The filter cartridge 12 is then fastened in direct engagement with the pi to face 14. In the engaged state, the skirt 24 essentially relaxes to its pre-engaged position, but still exerts some pressure against the projecting flange 22 - that is, creates an interence with this-- to provide an essentially air-tight seal between the components. To obtain such interference, the surface 28 projecting radially inwardly has a circumference, or in this circular configuration, a diameter that is non-inally smaller than the circumference or diameter of the surface 26 projecting radially outwardly. The seal can be achieved without the use of a package or other appropriate sealing mechanism. In this way, when the respirator is carried by a person, the inhaled air enters the interior of the facepiece 14, essentially by the exclusive passage from the outlet opening 23 on the filter cartridge 12, through the inlet opening. 19 on the facepiece 14. A conduit 25 is located behind the filter element, to facilitate the flow of air from the filter element through the outlet opening 23. The outlet and inlet openings substantially encompass an area smaller (for example, they have a substantially smaller circumference) than the circumference of the filter element. The pressure-tight seal may consist essentially of the projecting flange 22 and the skirt 24. The exhaled air may exit the interior 27 of the facepiece through an exhalation gate 31. The surface 28 which projects radially inwardly on the inside of the skirt 24, can take a variety of forms. For example, the surface projecting radially inward may be, as shown, a slightly inwardly angled surface (less than 90 °), or may be in the form of a rib, bevel, cam, or other inward facing projection. When the skirt 24 is in a circular configuration, its internal diameter preferably decreases axially in the direction of the end 30. The surface 26 projects radially outwardly on the projection flange 22., may also take a variety of shapes, including those listed above for the skirt 24. Conceivably, the projecting flange 22 may also have a groove (not shown) into which a corresponding flange is engaged from the skirt 24. In this way , the respirator of the invention includes a snap-fit coupling means comprising a protruding male member or flange 22, and a female member or skirt 24, wherein during the coupling of the filter cartridge 12 to the structure 22 receiving the In this case, the protruding flange 22 is first compressed and then expanded radially outwardly and the skirt 24 first expands and then compresses radially in an inward direction. The compression of the flange 22 and the expansion of the skirt 24 occur preferably essentially simultaneously, and the subsequent expansion of the flange 22 and the compression of the skirt 24 also occur simultaneously. A snap fit could also be achieved by having only one of the flange or skirt expanded and contracted, and having the other stay essentially static. Surfaces 26 and 28 projecting radially outwardly and inwardly may influence the ease, or otherwise the difficulty, of attaching and removing the filter cartridge. Increasing the size of. the surfaces 26 and 28 projecting radially outwardly and radially inwardly, the degree to which the skirt 24 is stretched radially outwardly increases, which, in turn, can make the coupling or removal more difficult. Also, the geometry of the surfaces 26 and 28 can influence how gradually or suddenly the filter cartridge 12 is adjusted in position. The material properties of the component parts are also a relevant factor in determining the proper forces to manually couple and manually separate the parts. What is meant by "manually" is that the filter cartridge can be easily coupled and removed from the facepiece by using the user's hands without the assistance from any mechanical source separate from the respirator. There is no need for any external tool or instrument, or need to destroy or dismember the respirator, to attach or remove the filter cartridge from the facepiece. The properties of the materials and other parameters can be adjusted to provide a desirable balance between a comfortable secure coupling and easy removal capacity. It has been found that a force of 10 to 60 Newtons can provide ease of removal and still provide a secure coupling, and that a withdrawal force of 15 to 25 Newtons is re-efferred. The skirt 24 is preferably made of an elastic polymeric resin capable of performing elastic deformation to allow the skirt 24 to fit over the projecting flange 22 and return to its initial approximate dimension. Materials with a flexural modulus of 2 x 108 to 30 x 108 Pascals (approximately 30,000 to 400,000 psi) at 22 ° C (73 ° F) may be appropriate for this purpose. When the flexural modulus is less than this range, substantial deformation or stretching may be necessary to ensure that a good seal is made between the cartridge and the facepiece, making it problematic to secure the first to the last. When the flexural modulus is greater than this range, the material can be difficult to deform, making the force required for removal undesirably large, and undesirably narrow manufacturing tolerances. The skirt material is also preferably a thermoplastic to facilitate manufacture. Some useful materials for the formation of a skirt 24 include polyethylene, polypropylene and thermoplastic rubbers. Low density polyethylene, such as Dowlexs 2553 polyethylene (Dow Chemical Company, Midland, Michigan) which has a flex modulus of 6.6 x 10 Pascals (approximately 95,000 psi), is a particularly appropriate material. High density polyethylene, such as Dow 8454, which has a flex modulus of 9.5 x 103 Pascals, is also particularly suitable. One embodiment of this invention has an injection molded filter cartridge, made of low density polyethylene, a bonded filter element which is compressively adjusted within the housing of the cartridge, and optionally a particulate filter stacked on the filter element United. The bonded filter element can be produced in accordance with the teachings of U.S. Patent Nos. 5,033,465 and 5,078,132 to Braun and Re ow. The filter element for particulate material may be an electrically charged fibrous network; see, for example, US Patent Re. 32,171 or US Patent Re. 30,782 to Van Turnhout. The projecting flange 22 is preferably made of a material that is somewhat stiffer than the skirt material. Materials having a flexural modulus greater than 6 x 10a Pascals (approximately 95,000 psi) at 22 ° C (73 ° F) are preferably used to form the flange 22. Typically, the flange 22 has a low flex modulus. 70 x 10"Pascals (approximately 1,000,000 psi) Examples of suitable materials include acrylonitrile-butadiene-styrene (ABS) copolymers, acetals, polycarbonates, polyethylene, polypropylene, polystyrene, etc. Polypropylene, such as Amoco® polypropylene 3234 (Amoco Chemical Company, Chicago, Illinois), which is believed to have a flexural modulus of 17 x 10 * Pascals (245,000 psi), is a particularly suitable material for use in the formation of the projecting flange 22. As As indicated above, when the skirt 24 is put into engagement with the flange 22, there is an audible noise such as a "click." An audible noise alerts the user that the cartridge is in a position ready for use. The use can be provided by clicking when the skirt is stretched beyond a certain limit, and then suddenly relaxed. In some cases, there may be a need to provide an additional securing means beyond press fit. Additional securing means may be provided to help prevent accidental uncoupling of the filter cartridge from a facepiece, such as from an unexpected lateral force. The additional securing means could take the form of a hook 34 shown in Figures 3 and 5, positioned laterally from the skirt 24 and the structure 22 to receive the cartridge. The hook 34 is insertable into a corresponding slot 36 in the facepiece 14. The coupling of the filter cartridge 12 to the facepiece 14 first involves the engagement of the hook 34 in the groove 36. The hook 34 can act as a hinge around which pivots the cartridge 12 as it is pressed generally axially towards or away from the facepiece 14. A tab 38 may be provided on the cartridge 12, to facilitate uncoupling of the facepiece cartridge 14. When the hook 34 and slot 36 are not used on the filter cartridge 12, the cartridge can be clamped around its periphery to cause its separation from the facepiece 14. Levering is another factor that affects the ease or difficulty of the operation. coupling or removal of the filter cartridge. Because the skirt 24 is of appropriate dimensions to span an area smaller than the filter 16, it is not concentric with or axially displaced from the center of the filter cartridge 16, the lever operation being available to separate the cartridge 12 from the facepiece 14. As shown, the projected area of the skirt is not encompassed by the projected area of the filter element, for example, the radius of the filter element is smaller than the sum of the displacement plus the sum of the radius of the exit opening. As shown, the projected area of the skirt is not encompassed by the projected area of the filter element - that is, the radius of the filter element is less than the sum of the displacement plus the radius of the exit opening. If the hook 34 is uncoupled or not used, a person holding the filter cartridge 12 can simply pull from the opposite end 32 to the skirt. 24, to separate the cartridge 12 from the facepiece 14. Although the present invention has been illustrated with the facepiece 14 having a protruding flange 22 and the filter cartridge 12 having a skirt 24, it may be possible in this invention to perform the inverse. That is, alternatively the filter cartridge could be provided with a protruding flange, and the facepiece could have the skirt. Instead of a protruding flange and a skirt, other suitable mechanisms for providing a snap fit in accordance with this invention may be considered. Thus, it is understood that the invention is not limited to the modalities described above, but must be controlled by the limitations described in the claims and in any equivalents thereof. It is also understood that this invention may be practiced in the absence of any limitation or circumstance not explicitly described above.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following:

Claims (12)

1. A respirator, characterized in that it comprises: a) a face piece of appropriate size to fit at least on a person's nose and mouth; b) a cartridge receiving structure located on the facepiece; and c) a filter cartridge having a housing within which a filter element is contained, the filter cartridge is capable of being manually held in engagement with the cartridge receiving structure to produce an audible noise, the coupling being instantly obtainable by pressing the filter cartridge against the receiving structure, without rotational movement, the filter cartridge is furthermore capable of being easily separated from the receiving structure of the cartridge by manually pulling it.

2. The respirator according to claim 1, characterized in that the filter cartridge includes a cylindrical housing containing a cylindrical filter element, the cylindrical filter element is displaced axially from the cartridge receiving structure, and wherein the receiving structure of the cartridge comprises an opening having a circumference that is substantially less than the circumference of the cylindrical filter element.

3. The respirator according to claims 1 to 2, characterized in that the filter cartridge can be put into engagement with the facepiece by the steps consisting essentially of pressing the filter cartridge against the facepiece in a direction normal to the workpiece Facial, and wherein the filter cartridge can be removed from the facepiece by the steps essentially consisting of holding the filter cartridge and pulling it axially in a direction normal to the facepiece.

4. The respirator according to claims 1 to 3, characterized in that it is a negative pressure respirator.

5. The respirator according to claims 1 to 4, characterized in that the cartridge receiving structure is in the form of a protruding flange, the filter cartridge includes a skirt that engages the projecting flange, and wherein the protruding flange it has a surface that projects radially outwards, which is coupled to a surface that projects radially inward, on the skirt.

6. The respirator according to claim 5, characterized in that the skirt expands radially outwardly from a rest condition, and the projecting flange is pressed radially inward, when the filter cartridge is pressed towards the facepiece.

7. The respirator according to claims 5 and 6, characterized in that the skirt exerts pressure on the projecting flange during coupling, to create an essentially air-tight seal between the skirt and the flange.

8. The respirator according to claims 1 to 7, characterized in that the filter cartridge is coupled with the cartridge receiving structure, such that a force of 10 to 60 Newtons is required to remove the filter cartridge from the structure for the receipt of the cartridge.

9. The respirator according to claims 5 to 7, characterized in that the skirt is made of a polymeric resin having a flexural modulus of 6 x 10 * at 30 x 10a Pascals, and wherein the projecting flange is made of a material more rigid polymer that has a flexural modulus of 6 x 108 Pascals up to 70 x 108 Pascals.

10. The respirator according to claims 1 to 11, characterized in that it includes a snap coupling mechanism comprising a male member and a female member, wherein during the coupling of the filter cartridge to the cartridge receiving structure, i) the male member is first compressed and then radially outwardly expanded, or ii) the female member first expands and then compresses radially inward, or a combination of i) and ii) occurs essentially simultaneously.

11. The respirator according to claims 1 to 10, further characterized in that it includes a second coupling mechanism that is laterally positioned from the snap coupling mechanism.

12. A filter cartridge useful for filtering ontaminants that are inhaled through a respirator worn by a person and to allow instant coupling and removal from a respirator facepiece, the filter cartridge is characterized in that it comprises a housing and an element of filter, the filter element residing in the housing, and the housing includes a means for allowing the filter cartridge to be manually placed in engagement with a cartridge receiving structure by pressing the filter cartridge against a cartridge receiving structure on the facepiece, without using rotational movement, and to allow the filter cartridge to be easily separated from the cartridge receiving structure by manually pulling it out of the filter cartridge.