Breathing valve assembly with diaphragm control of the exhaust ports

Abstract

A breathing apparatus having an exhaust valve and a diaphragm actuated inlet valve, wherein the exhaust valve includes a sealing surface against which the diaphragm normally is sealingly engaged to close the opening and from which the diaphragm is disengaged upon exhalation to open the exhaust valve.

I claim: 
     
       1. In a breathing apparatus .Iadd.capable of operating in the pressure demand mode and .Iaddend.having a hollow casing with an opening in one wall thereof, a flexible diaphragm .Iadd.having a relatively thin annular portion, the diaphragm being .Iaddend.secured at its periphery relative to said casing and having internal and external surfaces .Iadd.subject to fluid pressure and .Iaddend.positioned across said opening, said diaphragm forming a chamber in conjunction with said casing and being movable in response to variations in differential pressure across said diaphragm, a breathing fluid .Iadd.supply, an .Iaddend.inlet .Iadd.valve connecting said fluid supply .Iaddend.to said chamber, means for opening said inlet .Iadd.valve .Iaddend.responsive to movement of said diaphragm inwardly of said chamber upon a reduction of pressure within said chamber, .Iadd.a breathing port from said chamber adapted to be connected to a user, .Iaddend.a fluid outlet from said chamber, .[.and.]. means for opening said outlet when .Iadd.the .Iaddend.pressure within said chamber exceeds the .Iadd.pressure bearing upon the external surface by .Iaddend.a .Iadd.relatively constant .Iaddend.predetermined .[.relative pressure.]. .Iadd.overpressure, and pressure maintaining means capable of maintaining the fluid pressure bearing upon the external surface of said diaphragm at a relatively constant pressure while the inlet and outlet are sequentially opened and closed; .Iaddend.the improvement wherein said means for opening .Iadd.said outlet .Iaddend.comprises arranging said diaphragm and said outlet so that .Iadd.the relatively thin annular portion of .Iaddend.said diaphragm .[.itself.]. normally closes said outlet and maintains said outlet closed until the chamber pressure .[.exceeds a predetermined value.]. .Iadd.attains said overpressure .Iaddend.whereupon movement of said diaphragm outwardly of said chamber opens said outlet to vent fluid from said chamber.Iadd., together with supporting means adjacent said outlet for supporting the relatively thin annular portion of said diaphragm so that the effective area of the internal and external surface of said diaphragm subject to differential pressure remains in a substantially constant ratio as said diaphragm opens said outlet whereby the overpressure necessary to open said diaphragm remains substantially constant even though the flow rate and pressure may vary. .Iaddend. 
     
     
       2. Breathing apparatus as defined in claim 1, said apparatus .[.being of the straight demand type.]. .Iadd.also being capable of operating in the straight demand mode.Iaddend.. 
     
     
       3. Breathing apparatus as defined in claim 1, said .[.apparatus being of the pressure-demand type.]. .Iadd.supporting means causing said effective area of said diaphragm to remain in a substantially constant ratio of 1:1.Iaddend.. 
     
     
       4. Breathing apparatus as defined in claim 1, said means for opening said inlet including a tilt valve having a stem engaged by said diaphragm upon inward movement thereof to open said valve and spring means biasing said valve to .Iadd.an .Iaddend.inlet closing position. 
     
     
       5. Breathing apparatus as defined in claim 1, .[.together with.]. .Iadd.in which .Iaddend.a sealing surface is .Iadd.is disposed adjacent said outlet and .Iaddend.about said opening .[.against which.]..Iadd., .Iaddend.a portion of the internal surface of said diaphragm normally .[.sealing engages to close.]. .Iadd.engaging said sealing surface to close .Iaddend.said outlet and from which at least a portion of said diaphragm is disengaged when the pressure within said chamber exceeds a predetermined value, said diaphragm and surface thereby acting as an outlet valve. 
     
     
       6. Breathing apparatus as defined in claim .[.5.]. .Iadd.1 .Iaddend., said diaphragm having a built-in pre-load sufficient to maintain said outlet valve normally closed in all positions of orientation of said apparatus. 
     
     
       7. In a breathing apparatus .Iadd.capable of operating in the pressure demand mode and .Iaddend.having a hollow casing with an opening in one wall thereof, a flexible diaphragm .Iadd.having a relatively thin annular portion, the diaphragm being .Iaddend.secured at its periphery relative to said casing and having internal and external surfaces .Iadd.subject to fluid pressure and .Iaddend.positioned across said opening, said diaphragm forming a chamber in conjunction with said casing and being movable in response to variations in differential pressure across said diaphragm, a breathing fluid .Iadd.supply, an .Iaddend.inlet .Iadd.valve connecting said fluid supply .Iaddend.to said chamber, means for opening said inlet .Iadd.valve .Iaddend.responsive to movement of said diaphragm inwardly of said chamber upon a reduction of pressure within said chamber, a fluid outlet from said chamber .[.and.]..Iadd., a breathing port from said chamber adapted to be connected to a user, .Iaddend.means for opening said outlet when pressure within said chamber exceeds .Iadd.the pressure bearing upon the external surface by .Iaddend.a .Iadd.relatively constant .Iaddend.predetermined .[.relative pressure.]. .Iadd.overpressure, and pressure maintaining means capable of maintaining the fluid pressure bearing upon the external surface of said diaphragm of a relatively constant pressure while the inlet and outlet are sequentially opened and closed; .Iaddend.the improvement wherein said means for opening .Iadd.said outlet .Iaddend.comprises arranging said diaphragm and said outlet so that .Iadd.the relatively thin annular portion of .Iaddend.said diaphragm .[.itself.]. normally closes said outlet and maintains said outlet closed until the chamber pressure .[.exceeds a predetermined value.]. .Iadd.attains said overpressure .Iaddend.whereupon said diaphragm opens said outlet to vent fluid from said chamber, .Iadd.together with supporting means adjacent said outlet for supporting said annular portion of said diaphragm so that the effective area of the internal and external surfaces of said diaphragm subject to differential pressure remains in a substantially constant ratio as said diaphragm opens said outlet, and .Iaddend.wherein said .[.external surface of said diaphragm is protected by.]. .Iadd.pressure maintaining means includes .Iaddend.a cover defining with said diaphragm a second chamber, said second chamber .Iadd.protecting the external surface of said diaphragm and .Iaddend.being vented to the exterior of said apparatus. 
     
     
       8. Breathing apparatus as defined in claim 7, said diaphragm having a built-in pre-load sufficient to maintain said outlet valve normally closed in all positions of orientation of said apparatus. 
     
     
       9. Pressure-demand breathing apparatus as defined in claim 7, together with means for maintaining a positive pressure within said second chamber relative to ambient atmosphere. 
     
     
       10. Pressure-demand breathing apparatus as defined in claim 9, wherein said means for maintaining a positive pressure include a bleed passage from said inlet to said second chamber, and .Iadd.an .Iaddend.aneroid .[.means.]. controlling the vent from said second chamber. 
     
     
       11. Pressure-demand breathing apparatus as defined in claim 9, said outlet comprising .[.a.]. .Iadd.an annular .Iaddend.series of .[.alternating.]. ports .[.and support.]..Iadd., supporting .Iaddend.means .[.around said opening.]. .Iadd.consisting of an annular series of radial bars separating said ports.Iaddend., and .[.a.]. .Iadd.an annular sealing surface .[.around.]. .Iadd.adjacent .Iaddend.said .Iadd.outlet .Iaddend.inwardly of said ports and .[.suppport.]. .Iadd.supporting .Iaddend.means, said internal surface of said diaphragm normally .[.sealing.]. .Iadd.sealingly .Iaddend.engaging said sealing surface to close said outlet, said .[.support.]. supporting means providing support for .Iadd.the relatively thin annular portion of .Iaddend.said diaphragm outwardly of said sealing surface .Iadd.so that the differential pressure across said diaphragm needed to lift said diaphragm from said sealing surface will remain almost constant to maintain the desired substantially uniform outlet opening action. .Iaddend. 
     
     
       12. In a breathing apparatus .Iadd.capable of operating in the pressure demand mode and .Iaddend.having a hollow casing with an opening in one wall thereof, a flexible diaphragm .Iadd.having a relatively thin annular portion, the diaphragm being .Iaddend.secured at its periphery relative to said casing and having internal and external surfaces .Iadd.subject to fluid pressure and .Iaddend.positioned across said opening, said diaphragm forming a chamber in conjunction with said casing and being movable in response to variations in differential pressure across said diaphragm, a breathing fluid .Iadd.supply, an .Iaddend.inlet .Iadd.valve connecting said fluid supply .Iaddend.to said chamber, means for opening said inlet .Iadd.valve .Iaddend.responsive to movement of said diaphragm inwardly of said chamber upon a reduction of pressure within said chamber, a fluid outlet from said chamber .[.and.]..Iadd., a breathing port from said chamber adapted to be connected to a user, .Iaddend.means for opening said outlet when pressure within said chamber exceeds .Iadd.the pressure bearing upon the external surface by .Iaddend.a .Iadd.relatively constant .Iaddend.predetermined .[.relative pressure.]. .Iadd.overpressure, and pressure maintaining means capable of maintaining the fluid pressure bearing upon the external surface of said diaphragm of a relatively constant pressure while the inlet and outlet are sequentially opened and closed; .Iaddend.the improvement wherein said means for opening .Iadd.said outlet .Iaddend.comprises arranging said diaphragm and said outlet so that .Iadd.the relatively thin annular portion of .Iaddend.said diaphragm normally closes said outlet and maintains said outlet closed until the chamber pressure .[.exceeds a predetermined value.]. .Iadd.attains said overpressure .Iaddend.whereupon said diaphragm opens said outlet to vent fluid from said chamber, together with a sealing surface .Iadd.extending .Iaddend.about said opening .Iadd.and through which said outlet extends and .Iaddend.against which a portion of the internal surface of .Iadd.the annular portion of .Iaddend.said diaphragm normally sealingly engages to close said outlet and from which at least a portion of said diaphragm is disengaged when the pressure within said chamber exceeds a predetermined value, said diaphragm and said .Iadd.sealing .Iaddend.surface thereby acting as an outlet valve, said outlet comprising a series of alternating ports and .[.support.]. .Iadd.supporting .Iaddend.means .[.around said opening,.]. .Iadd.in .Iaddend.said sealing surface .[.being interposed between said series of outlet ports and said opening, and said opening.]., and said .[.support.]. .Iadd.supporting .Iaddend.means providing support for .Iadd.the relatively thin annular portion of .Iaddend.said diaphragm .[.outwardly of said sealing surface.]. .Iadd.so that the effective area of the internal and external surfaces of said diaphragm subject to differential pressure remains in a substantially constant ratio as said diaphragm opens said outlet whereby the differential pressure across said diaphragm needed to lift said diaphragm from said sealing surface will remain almost constant, thereby providing the desired outlet opening action..Iaddend. 
     
     
       13. Breathing apparatus as defined in claim 12, said apparatus being of the pressure-demand type having means for maintaining a positive pressure relative to ambient atmosphere on said external surface of said diaphragm. .Iadd.14. Breathing apparatus as defined in claim 1, said flexible diaphragm being so shaped that when the outlet is opened it is not necessary to stretch said diaphragm, the relatively thin portion of the diaphragm rolling away from said outlet. .Iaddend.