Air flow control devices

Claim 1

IN AN AIR BLENDING AND VOLUME CONTROLLING DEVICE INCLUDING A HOUSING HAVING TWO CYLINDRICAL AIR INLET CONDUITS AND ONE CYLINDRICAL AIR OUTLET CONDUIT IN COMMON COMMUNICATION WITH EACH OTHER, THE PROVISION OF: A PNEUMATICALLY EXPANDABLE ELASTIC MEANS IN EACH OF AT LEAST TWO OF SAID CONDUITS FOR CLOSING THE ASSOCIATED CONDUIT TO THE PASSAGE OF AIR THERETHROUGH UPON FULL EXPANSION OF SAID ELASTIC MEANS WITHIN SAID ASSOCIATED CONDUIT; MOUNTING MEANS WITHIN EACH OF SAID TWO CONDUITS FOR MOUNTING THE ASSOCIATED ELASTIC MEANS AT A LONGITUDINAL MID-PLANE OF THE CONDUIT TO ALLOW AIR PASSAGE THROUGH SAID CONDUIT ON OPPOSITE SIDES OF SAID ELASTIC MEANS WHEN SAID ELASTIC MEANS IS OTHER THAN FULLY INFLATED; AND MEANS FOR INFLATING AND DEFLATING ONE OF SAID ELASTIC MEANS IN RESPONSE TO A THERMOSTAT AND MEANS TO INFLATE AND DEFLATE THE OTHER OF SAID ELASTIC MEANS IN RESPONSE TO VARIATIONS IN THE VOLUME OF AIR FLOW THROUGH SAID OUTLET CONDUIT; WHEREIN EACH OF SAID ELASTIC MEANS INCLUDES A PAIR OF OPPOSED SHEET-LIKE ELASTIC ELEMENTS HAVING MARGINAL AREAS SECURED TO EACH OTHER AND ENGAGED BY SAID MOUNTING MEANS AND EACH OF SAID ELASTIC MEANS BEING EXPANDABLE OUTWARDLY FROM SAID MID-PLANE OF THE ASSOCIATED CONDUIT TO FORM A HOLLOW GENERALLY SPHERICAL SHAPE ABUTTING THE INTERIOR WALL OF SAID ASSOCIATED CONDUIT, FURTHER EXPANSION OF SAID ELASTIC MEANS BEYOND SAID SPHERICAL SHAPE BEING RETAINED BY THE SURROUNDING ASSOCIATED CYLINDRICAL CONDUIT.