Powered air-purifying respirator with improved internal baffle system

Abstract

A mask assembly for a powered air-purifying respirator is provided. The assembly includes a mask with at least one peripheral vent and an insert positioned within or formed integrally with the mask. The insert includes an inlet for receiving air, a central baffle that redirects air from the inlet peripherally away from a user's face, and a downstream peripheral baffle that redirects the airflow toward the user's face. This dual redirection reduces airflow velocity at the face and limits direct loss of air through the peripheral vent. The central baffle may define a substantially uniform gap with the mask wall, and the central and peripheral baffles may have selected shapes and relative orientations to control airflow.

Description

POWERED AIR-PURIFYING RESPIRATOR WITH IMPROVED INTERNAL BAFFLE SYSTEMTechnical Field

[0001] The present invention relates to powered air-purifying respirators.Background of the Invention

[0002] Respirators are widely used to provide users with filtered air in environments where contaminants may be present. Powered air-purifying respirators (PAPRs) are respirators draw in and filter ambient air before delivering it to the user. Unlike passive respirators, which rely on the user's breathing to pull air through a filter, PAPRs reduce breathing resistance and provide a continuous supply of clean air, enhancing comfort and usability.

[0003] However, conventional PAPRs can direct airflow onto the user’s nose, mouth, and eyes, causing discomfort and irritation. Loose-fitting PAPR masks, while having advantages such as greater comfort over extended wear periods and eliminating the need for fit testing, require higher airflow than tight-fitting PAPR masks thereby exacerbating the discomfort of airflow directly impinging on the user’s face.Conventional PAPRs also often provide imprecise airflow measurements. Improved PAPRs that address these concerns are desirable.Summary of the Invention

[0004] One aspect of the invention relates to a mask assembly for use with a powered air-purifying respirator. The assembly includes a mask with a peripheral vent and an internal insert that directs incoming air along a controlled flow path. The insert includes an inlet for receiving air and a central baffle that redirects the airflow laterally toward the periphery of the mask before it reaches the user’s face.

[0005] Downstream of the central baffle, a peripheral baffle redirects the air once more toward the user’s face. This two-stage redirection reduces the velocity of airflow impinging on the face while also limiting direct escape of air through the peripheral vent.

[0006] The central baffle may extend across most of the area between itself and the inner mask wall — typically around seventy to ninety percent — forming a substantially uniform gap around its edge. The central baffle may be inclined relative to horizontalat angles in the range of sixty to eighty degrees, for example around seventy degrees, and may exhibit a semi-elliptical profile. In some forms, the downstream face of the central baffle is concave while the upstream face is convex.

[0007] The peripheral baffle may be positioned so that it does not overlap the central baffle; if the two structures were placed in a hypothetical common plane, a separation would remain between the outer edge of the central baffle and the distal edge of the peripheral baffle. The peripheral baffle may take the form of a raised ridge, flange, or step, and in some examples presents an inverted U-shaped profile. The plane of the peripheral baffle may be parallel to that of the central baffle.

[0008] Additional structural features may include a septum integrated with the central baffle to provide reinforcement, and retention projections on the inner surface of the mask to maintain the insert in proper alignment. In some arrangements, a deflector directs air exiting the inlet toward the central baffle to optimize distribution. The peripheral vent may be implemented as one or more elongated gaps or as openings defined by wavy or undulating edges to promote efficient venting of exhaled air while helping maintain a positive internal pressure within the mask.

[0009] The foregoing provides only one aspect of the invention, and other aspects and implementations are also within the scope of the invention.Brief Description of the Drawings

[0010] In drawings which illustrate non-limiting embodiments of the invention:

[0011] Figure 1 is a perspective view of a powered air-purifying respirator showing the various assemblies including the mask assembly, fan unit assembly, hose assembly, mask strap assembly, and fan unit harness assembly.

[0012] Figure 2 is an exploded side view of the mask assembly showing the retention cover, mask, and insert, as well as features such as the exhaust valve and peripheral vents.

[0013] Figure 3 is a top perspective exploded view of the mask and insert, highlighting the exhaust valve, inlet, deflector, central baffle, and septum.

[0014] Figure 4 is a bottom perspective exploded view of the mask and insert, showing the inlet, deflector, central baffle, and retention projections.

[0015] Figure 5 is a rear view of the mask assembly emphasizing the mask and the insert with its peripheral baffle.

[0016] Figure 6 is a side cross-sectional view of the mask assembly showing the inlet, deflector, central baffle, and peripheral baffle.

[0017] Figure 7 is a top cross-sectional view of the mask assembly showing the central baffle, septum, and peripheral baffle with airflow paths indicated.

[0018] Figure 8 is a side cross-sectional view of the fan unit assembly illustrating the filter, fan, duct, pitot tube, and the narrowing section of the duct with indicated airflow.

[0019] Figure 9 is a side cross-sectional view of the pitot tube showing the dynamic pressure chamber, dynamic pressure port, dynamic pressure conduit, dynamic pressure sensor, static pressure chamber, static pressure port, static pressure conduit, and static pressure sensor, along with the partition wall.

[0020] Figure 10 is a downstream perspective view of the pitot tube.

[0021] Figure 11 is an upstream perspective view of the pitot tube.Detailed Description of the Invention

[0022] Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well-known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0023] The present invention integrates multiple assemblies of a powered airpurifying respirator to provide a comfortable and efficient delivery of filtered air to a user.

[0024] Figure 1 shows a powered air-purifying respirator 10 according to an embodiment. Ambient air is drawn into a fan unit assembly 200. Air is filtered within fan unit assembly 200. Fan unit assembly 200 includes a pitot tube configured to measure differential pressure between dynamic and static airflow conditions for improved prediction of volumetric airflow, as further described below. Air is then directed through a hose assembly 300 to a mask assembly 100. Mask assembly 100 includes internal baffles for redirecting the air multiple times to moderate airflow impinging on the user, as further described below. A mask strap assembly 400 and a fan unit harness assembly 500 position respirator 10 on the user.

[0025] Figures 2 to 7 show mask assembly 100 according to an embodiment. Mask assembly 100 includes a loose-fitting mask 104, retention cover 102, and an insert106. Mask 104 may be primarily formed of an elastomeric material. Mask 104 includes exhaust valves 108 and peripheral vents 110, which work together to ensure that exhaled air is effectively vented, that positive pressure is maintained to prevent ingress of contaminants, and that the environment inside the mask remains comfortable and safe for the user.

[0026] Peripheral vents 110 may be configured as one or more elongated gaps in some embodiments. In other embodiments, peripheral vents 110 may be defined by wavy, undulating, or serpentine edges that form a continuous venting path. These wavy edges may enhance venting performance by increasing the effective vent area while maintaining structural integrity of mask 104.

[0027] Alternative embodiments may include vents with irregular or sinuous contours, which are designed to optimize airflow and exhaust efficiency. The specific shape of peripheral vents 110 may be varied to meet design or performance requirements.

[0028] Regardless of the specific geometry, these vent configurations share the functional purpose of facilitating efficient exhaust airflow while helping maintain a positive pressure environment within the mask. In all such variations, the vent path remains continuous to ensure reliable exhaust flow.

[0029] Mask 104 also includes a lower throughhole 105 configured to receive and resiliently retain a rigid inlet 112 of an insert 106, to secure the lower portion of insert 106 within mask 104. A retention cover 102 is affixed — either bonded or riveted — to mask 104. Mask strap assembly 400 and retention cover 102 cooperate to secure mask assembly 100 to the user’s face.

[0030] Insert 106 of mask assembly 100 receives air from hose assembly 300 through inlet 112. Upon entering insert 106, the air encounters a deflector 114, which is configured to efficiently channel air exiting inlet 112 toward central baffle 116. In the illustrated embodiment, deflector 114 comprises two triangular walls flanking a central trapezoidal portion.

[0031] The bases of the triangular walls and the top edge of the trapezoidal portion are interconnected to form a continuous structure that extends along a major portion of inlet 112’s exit edge periphery. The apexes of the triangular walls and the bottom edge of the trapezoidal portion converge and join to form a continuous connection with the lower edge of central baffle 116. This arrangement ensures that air is guidedseamlessly from inlet 112 to central baffle 116. Deflector 114 may be made of the same rigid material as inlet 112.

[0032] In embodiments where the inlet, deflector, and central baffle are integrally formed, they may be co-molded or otherwise manufactured from materials having compatible rigidity or flexibility appropriate to the intended airflow performance.

[0033] Central baffle 116 is positioned adjacent to the exit of inlet 112. In the illustrated embodiment, central baffle 116 has a semi-elliptical profile and is integrally formed with deflector 114 and inlet 112. Central baffle 116 may be made of an elastomeric material. Central baffle 116 is configured to redirect high velocity airflow from inlet 112 and deflector 114 peripherally, away from the user’s face, as shown by arrows 150 and 152 in Figure 7.

[0034] A major plane 117 of central baffle 116 is inclined at an angle 119 from the horizontal, where angle 119 represents an angle determined by the inventors to optimize airflow redirection. As shown in Figure 6, angle 119 is measured between major plane 117 defined by central baffle 116’s predominant surface and an imaginary horizontal plane 121 parallel to the ground. In some embodiments, angle 119 may be, for example, in the range of about 60 degrees to 80 degrees, or about 65 degrees to 75 degrees, or about 70 degrees as in the illustrated embodiment.

[0035] Also as shown in Figure 6, an imaginary plane 124 is defined by extending major plane 117 of central baffle 116 until it meets the inner wall of mask 104.Central baffle 116 is configured to cover about 70% to 90%, or about 75% to 85%, or about 80%, of the area enclosed by plane 124.

[0036] Consequently, gap 126 between the peripheral edge of the central baffle and the inner wall of mask 104 is substantially constant along the entire perimeter defined by plane 124. This configuration facilitates airflow being substantially uniformly redirected around central baffle 116 toward peripheral baffle 122.

[0037] The downstream surface of central baffle 116 may be concave to provide additional clearance to the mouth of the user. The convexity of the upstream surface of central baffle 116 may distribute a greater portion of the airflow toward lower sections of a peripheral baffle 122, described further below, for better overall airflow distribution. This geometry assists in promoting more even distribution of redirected airflow toward the peripheral baffle and contributes to user comfort.

[0038] To stabilize the structure and maintain the desired airflow pattern, a septum 118 is provided to reinforce central baffle 116. Additionally, retention projections 120 are provided on an inner surface of mask 104 to receive septum 118, preventing rotation of septum 118 and thereby ensuring overall proper alignment of insert 106 within mask 104.

[0039] In the illustrated embodiment, retention projections 120 comprise pairs of short tabs. As best shown in Figure 6, the top of septum 118 also hooks between the top of peripheral baffle 122 and the inner wall of mask 104, to secure the upper portion of insert 106 within mask 104.

[0040] Peripheral baffle 122 extends from the inner wall of mask 104. In the illustrated embodiment, peripheral baffle 122 has an inverted U-shaped profile. As best shown in Figure 7, a plane 130 of peripheral baffle 122 is generally parallel to plane 117 of central baffle 116 but downstream relative to central baffle 116 by an offset 128. Peripheral baffle 122 may be a ridge, a flange, a step, and the like. Peripheral baffle 122 guides redirected airflow from central baffle 116 toward the user, and away from being lost directly to peripheral vents 110 and top of mask 104, in the direction of arrow 154.

[0041] Peripheral baffle 122 is configured such that it does not overlap central baffle 116. That is, if peripheral baffle 122 and central baffle 116 were hypothetically coplanar (which they are not), a defined gap would exist between the peripheral edge of central baffle 116 and the distal edge of peripheral baffle 122. In some embodiments, such a gap may not be present, i.e., the distal edge of peripheral baffle 122 may abut or overlap with the peripheral edge of central baffle 116 in the hypothetical coplanar situation, but in such embodiments gap 128 would be greater.

[0042] Offset 128 and gap 126 thus cooperate to ensure that central baffle 116 and peripheral baffle 122 maintain their independent functional surfaces, and together define a transition zone that facilitates the redirection of airflow as shown by arrow 154.

[0043] The combined effect of central baffle 116 and peripheral baffle 122 is therefore a moderated, comfortable stream of air that minimizes direct impact on the user while conserving airflow. These configurations were observed by the inventorsto reduce turbulence-induced measurement variation in prototype testing, thereby improving the consistency of differential pressure readings.

[0044] Figures 8 to 10 show a fan unit assembly 200 according to an embodiment. Fan unit assembly 200 includes a housing 201 which encloses a filter 202, fan 204, and duct 206. Ambient air is first drawn into the filter 202 in the direction of arrow 250, drawn into fan 204 in the direction of arrow 252, propelled by fan 204 into duct 206 in the direction 254, and finally expelled from duct 206 into hose assembly 300 in the direction of arrow 256.

[0045] In the illustrated embodiment, fan 204 is a centrifugal (impeller) fan. In other embodiments, fan 204 may be another type of suitable fan, such as a mixed-flow fan, depending on the design of fan unit assembly 200. Regardless, fan 204 generates turbulent flow, and shaded portions in Figure 8 show areas within fan unit assembly 200 that would typically experience turbulent flow of air.

[0046] A cylindrical pitot tube 208 is provided within duct 206 to monitor airflow. Pitot tube 208 is divided into an upstream-facing dynamic pressure chamber 210 and a downstream-facing static pressure chamber 212, which are separated by a partition wall 214. In dynamic pressure chamber 210, a dynamic pressure port 216 is provided at a bottom floor thereof and is connected to a dynamic pressure sensor 224 by an elongated S-shaped dynamic pressure conduit 220.

[0047] Similarly, static pressure chamber 212 includes a static pressure port 218 at a bottom floor thereof, which is connected to a static pressure sensor 226 via an elongated S-shaped static pressure conduit 222. In some embodiments S-shaped conduits may not be required in configurations where pressure sensors 224 / 226 are located close to pitot tube 208.

[0048] The inventors have determined that the following configurations enhance differential pressure measurement and, consequently, the accuracy of airflow prediction:• positioning pitot tube 208 at least about two times, or at least about three times, its own length downstream of fan 204. This spacing was found to minimize the impact of turbulent flow generated by fan 204, i.e., so that pitot tube 208 could be in airflow that is close to laminar flow as possible;• selecting the outer diameter of pitot tube 208 to be about 40% to 60%, or about 45% to 55%, or about 50% of the duct’s hydraulic diameter.• positioning pitot tube 208 at a narrowing portion 228 within duct 206 where the velocity of the airflow is increased;• providing pitot tube 208 in a tubular shape. Other shapes such as conical shapes and oblong shapes were found to be less effective; and• positioning pitot tube 208 so that its axial center substantially aligns with the center of duct 206’s cross-sectional area. Otherwise, conduits 220 / 222 were found to block more of the air flow or obstruct dynamic pressure chamber 210.

[0049] When respirator 10 is in use, filtered airflows from fan unit assembly 200 through duct 206, where the pitot tube 208 monitors the airflow conditions. This airflow data can be employed by control systems to adjust operational parameters. The air then travels via hose assembly 300 to mask assembly 100. Here, inlet 112 of the insert 106 is received securely through the deformed throughhole of elastomeric mask 104. Deflector 114 helps channel the air to central baffle 116 where the airflow is efficiently redirected to the periphery of mask 104. Finally, peripheral baffle 122 guides the moderated airflow toward the user’s nose and mouth, ensuring that the delivered air is of reduced speed and that direct high-velocity impingement is avoided. This integrated system of components ensures both efficient measurement of airflow and its optimal distribution to the user.

[0050] While a number of exemplary aspects and embodiments have been discussed above, various additional embodiments may include the following alternatives:• The retention cover may be absent, or the retention cover and mask may be integrally formed;• The mask and insert may be integrally formed;• The retention cover, mask and insert may be integrally formed;• The deflector may be absent, or of a different configuration (e.g. with rounded walls);• The central baffle may be a different shape, for example fully elliptical, trapezoidal, rectangular, and the like;• The central baffle may be flat instead of slightly con vex / con cave;• The central baffle may be perforated with small holes to allow some air to pass through to provide a pressure drop;• The septum may be absent, or substituted with other suitable means of stabilizing the central baffle and / or securing the insert in place;• The peripheral baffle may fully surround the central baffle, for example if the air from the inlet hits the central baffle more “head on” instead of from a lower angle;• The peripheral baffle, instead of being parallel with the central baffle, may be angled toward the central baffle (e.g. by up to 5 degrees) or angled away from the central baffle (e.g. by up to 15 degrees);• The inlet may pierce the middle of the mask horizontally, or at an angle close to perpendicular to the central baffle, and close to the middle of central baffle, or at any angle between the one illustrated in the Figures and the horizontal; and • The pitot tube is located in a section of the duct with a constant cross-section.

[0051] The embodiments described herein are provided by way of example only and are not intended to limit the invention except as set forth in the claims below.

Claims

Claims1. A mask assembly for a powered air-purifying respirator, the mask assembly comprising:a mask comprising a peripheral vent;an insert received within or integral with the mask, the insert comprising:an inlet for receiving air;a central baffle configured to redirect air from the inlet peripherally away from a user's face; anda peripheral baffle, offset downstream from the central baffle, configured to redirect air from the central baffle towards the user's face,whereby the dual redirection both reduces the velocity of air impinging on the user’s face and reduces direct loss of air to the peripheral vent.

2. A mask assembly according to claim 1 wherein the central baffle is configured to cover about 70% to 90% of an area defined by an imaginary plane extending from a major plane of the central baffle to an inner wall of the mask, and establish a gap of a substantially constant width between a peripheral edge of the central baffle and the inner wall.

3. A mask assembly according to claim 2 wherein the major plane of the central baffle is inclined at an angle from the horizontal, the angle being in a range of about 60° to 80°, or about 70°.

4. A mask assembly according to any of one claims 1 to 3 wherein the central baffle comprises a semi-elliptical profile.

5. A mask assembly according to any of one claims 1 to 4 wherein the central baffle comprises a concavity on a downstream face and a convexity on an upstream face.

6. A mask assembly according to any of one claims 1 to 5 wherein the peripheral baffle is non-overlapping with the central baffle such that, if the peripheral baffle and the central baffle were hypothetically co-planar, a defined gap would exist between the peripheral edge of the central baffle and a distal edge of the peripheral baffle.

7. A mask assembly according to any of one claims 1 to 6 wherein the peripheral baffle comprises raised ridge, flange or step.

8. A mask assembly according to any of one claims 1 to 7 wherein the peripheral baffle comprises an inverted U-shaped profile.

9. A mask assembly according to any of one claims 2 to 8 wherein the major plane of the central baffle and the plane of the peripheral baffle are parallel.

10. A mask assembly according to any of one claims 1 to 9 further comprising a septum integrated with the central baffle for reinforcing the central baffle, and retention projections on an inner surface of the mask to maintain alignment of the insert.

11. A mask assembly according to any of one claims 1 to 10 further comprising a deflector that channels air exiting the inlet toward the central baffle.

12. The mask assembly according to any of one claims 1 to 11 further comprising peripheral vents configured as one or more elongated gaps or defined by wavy, undulating edges to facilitate venting of exhaled air and maintain a positive pressure within the mask.

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