Bag diaphragms and bag diaphragm operated air dampers

Abstract

The present invention deals with a bag diaphragm comprising one or more flattened extremely flexible bags assembled together, to be mounted between rigid plates at a variable mean distance and to be inflated in operation by a variable pressure difference, and with an air damper operated by means of a bag diaphragm as mentioned above, this air damper being suitable for air conditioning plants, in constant flow, or constant variable flow, or mixing appliances, in fresh air and return air ducts, where an air flow is to be controlled, the operation of the air damper being possible without any electrical or pneumatic energy supply system, due to the particular characteristics of the aforesaid bag diaphragm and particular design of the damper.

I claim: 
     
       1. A pneumatically operated valve assembly comprising first and second rigid plate members mounted for movement relative to each other and being in oppositely facing relation to each other, guide means for guiding the movement of one of said members relative to the other of said members, bag means sandwiched between said plate members, .Iadd.said bag means including a plurality of stacked bags having air passage means between adjacent ones of said bags, .Iaddend.said bag means having first portions thereof fixedly secured to .Iadd.at least one of .Iaddend.said plate members and second portions thereof extending between said plate members, said second portions being characterized by the absence of any significant bending resistance .Iadd.to allow for the complete collapsing of said bag means due to the weight of one of said plate members upon deflation of said bag means, .Iaddend.and aperture means in said .Iadd.one of said plate members .Iaddend..[.first plate member.]. for admitting and exhausting air to and from said bag means to adjust the position of said second plate member relative to the position of said first plate member. 
     
     
       2. A valve assembly according to claim 1 including conduit means, said fast plate member being fixed relative to said conduit means. 
     
     
       3. A valve assembly according to claim 2 wherein said second plate member is pivotally mounted relative to said conduit means. 
     
     
       4. A valve assembly according to claim 2 wherein said first plate member is integral with said conduit means.  .[.5. A valve assembly according to claim 1 wherein said bag means includes a plurality of stacked bags having 
     
     
        air passage means between adjacent ones of said bags..]. 6. A valve assembly according to claim 2 wherein air passage means extend externally of said conduit means from the upstream side of said plate members to said 
     
     
        aperture means. 7. A valve assembly according to claim 6 wherein said air passage means has adjustable vent means for controlling the position of 
     
     
        said second plate member. 8. A valve assembly according to claim 7 wherein an apertured partition extends transversely across said conduit means, said second plate member being cooperable with said partition to control the flow of air through said conduit means.