Abstract:
A respirator having a combination demand air regulator to provide air to the user on demand and an exhaust check valve. The regulator diaphragm, by its inward movement during inhalation, causes the exhalation valve to close while regulating the intake of supply air. Conversely, the regulator diaphragm, by its outward movement during exhalation, causes the exhalation valve to open while keeping the demand valve closed.

Description:
BACKGROUND 
     This invention relates to protective breathing apparatus of the type of which a user wears a face mask connected to a source of air for use in toxic or oxygen deficient surroundings. More specifically, the subject matter is a combination demand air intake regulator and exhalation valve for such a breathing apparatus. 
     Typically, in the prior art, respirator systems have included air intake regulators and exhalation valves as separate components, separately mounted to a face mask. Such prior art arrangements have required separate apertures in the face mask and some redundancy in hardware for the separate valves. 
     The details, operation, and benefits of the present invention will now be described with reference to the accompanying drawing. 
    
    
     DRAWING 
     FIG. 1 is a sectional view of a combination inhalation regulator and exhalation valve according to this invention, in an instantaneous condition during exhalation when all valves are closed. 
     FIG. 2 is a partial view of the same inhalation regulator, exhalation valve in its condition during inhalation. 
     FIG. 3 is a partial view of the same inhalation regulatorexhalation valve in its condition during exhalation. 
     FIG. 4 is a sectional view taken along the line 4--4 of FIG. 1. 
     FIG. 5 is a sectional view taken along the line 5--5 of FIG. 1. 
    
    
     DESCRIPTION 
     Referring now to FIG. 1, an inhalation pressure demand regulator and exhalation valve, hereinafter &#34;regulator&#34; for short, is generally indicated at 2 and includes a body 4 and a cover 6. A flexible diaphragm 8 of silicone rubber or the like is secured around the periphery of body 4 and cover 6 and extends across the interior of the regulator, defining with body 4 an air chamber C therein. Regulator 2 is adapted to fit to a face mask so that air chamber C communicates with the mask interior or mask chamber C indicated at the broken away bottom portion of FIG. 1. 
     Regulator cover 6 includes a central indentation 10, forming a spring seat around which a conical spring 12 is seated and adapted to bear in compression against the cover 6. Cover 6 also includes a plurality of vent apertures 14 through which the atmosphere chamber of the regulator, between cover 6 and diaphragm 8, communicates with atmosphere. 
     A demand air valve 16 is mounted on the body 4 of the regulator to admit air on demand into the air chamber C from a pressure air supply line, indicated at 18. Demand valve 16 operates in a known manner, as more fully described in U.S. Pat. No. 3,145,721 to Miller. It suffices for the purpose of this description to summarize that valve 16 includes a valve stem 20 which extends from a valve member 22 to a stem head 24 which follows the displacement of diaphragm 8 to tilt the valve member 22, regulating the admission of air from air line 18. 
     Diaphragm 8 is flexible in order to float within the regulator body under the influence of the breathing of the user. That is, inhalation draws the diaphragm inward, or downward in the drawing, and exhalation pushes the diaphragm outward, upward in the drawing. The central portion of the diaphragm 8 is a rigid circular diaphragm plate 26, generally open and spoked in the center (FIG. 4) forming several aperture sectors 28 about a hub 30. Conical compression spring 12 is positioned between the cover 6, where it is centered around spring seat 10, and diaphragm 26 where it is centered around hub 30. 
     A rigid circular disc valve seat 32 is coaxial with diaphragm plate 26 and adapted to overlie aperature sectors 28 to open and close the same. A valve guide 34 is fixed to valve seat 32 and includes a central ring 36 with three seat legs 38, passing through apertures 28, to which valve seat 32 is mounted and three abutment legs 40 projecting outward the cover 6 of the regulator. Valve guide 34 with integral valve seat 32 is mounted to the diaphragm plate 26 by light compression springs 42, one fastened on each abutment leg 40. Valve guide 34 and valve seat 32 are biased by springs 42 in a light sealing position against diaphragm plate 26 and over the aperture sectors 28. The stem head 24 of demand air valve 16 bears on the valve seat 12. 
     OPERATION 
     As a reference or starting condition, consider the system at equilibrium with pressure in chamber C equal to ambient atmosphere. In this condition, spring 12 (which is adjustable though this is not shown for simplicity) holds diaphragm 8, and valve guide 34 with it, away from the abutment position of legs 40. That is legs 40 and valve guide and seat 34 and 32 are at some intermediate position between those shown in FIGS. 1 and 2. This pre set bias of spring 12 on the diaphragm and thereby on the member 32 is for the purpose of holding valve stem 20 and demand valve 16 at some open position. In other words, an equilibrium pressure condition is not tolerated by the system-pressure equilibrium creates mechanical demand for air from valve 16 until there is a positive pressure in chamber C, an imbalance to move the diaphragm 8 and valve guide and seat 34, 32 to their FIG. 1 positions. Thus a positive pressure is maintained in chamber C to prevent atmosphere inflow. 
     Next, consider this system at an instantaneous condition during exhalation as shown in FIG. 1 at which point, the user has exhaled some air and the increased pressure in air chamber, relative to ambient pressure, has moved the diaphragm 8 against the compression spring 12 to the position shown where legs 40 abut the cover, demand valve 16 is just closed and exhalation valve 32 still seated. 
     Now, during further exhalation by the user, as represented in FIG. 3, the diaphragm plate 26 is pushed upward with valve guide and seat 34, 32 held from further movement by the abutment of legs 40 against cover 6. While valve seat 32 is thus stopped, the further upward travel of diaphragm plate 26 against spring 12 opens the valve seat 32 for exhalation flow to ambient atmosphere as represented by the arrows. The demand air valve 16 remains closed here as it is in FIG. 1. 
     Next, during inhalation by the user, as represented in FIG. 2, the diaphragm plate 26 with valve guide 34 and valve seat 32 is drawn downward by the temporary drop in pressure in air chamber C. Exhalation valve seat 32 remains closed on the diaphragm plate 26 by the biasing action of springs 42. Downward moving valve seat 32, bearing against the stem head 24 of demand air valve 16, causes tilting of the stem and opening of the air valve 16 to allow demand air into the chamber C. As demand air raises the pressure in chamber C above that of ambient atmosphere (on the other side of diaphragm 8) the chamber C moves back against diaphragm 8 and spring 12 toward its FIG. 1 condition. 
     SUMMARY 
     To summarize the operation of this invention, the repeated cycle includes: 1. inhalation, FIG. 2, during which exhalation valve 32 is closed and demand air valve 16 is regulating, 2. exhalation, FIG. 1, during which demand air valve 16 reaches closing and exhalation valve 32 remains closed while positive mask pressure develops, and 3. exhalation, FIG. 3, during which demand air valve 16 remains closed and exhalation valve 32 is exhausting to atmosphere. 
     The present invention provides an effective, single apparatus which is a combination inhalation demand air regulator and exhalation valve. 
     The foregoing description and summary of this invention are given only by way of illustration and not of limitation. The concept and scope of the invention are limited by the following claims.