Fans having radial flow rotors in axial flow casings

Claim 1

IN A FAN HAVING AN OUTER CASING, CIRCULAR IN SECTION, A SMALLER INNER CASING, CIRCULAR IN SECTION, WITHIN SAID OUTER CASING AND CONCENTRIC THEREWITH, SAID INNER CASING HAVING A CLOSED DOWNSTREAM END WALL, AND HAVING AN UPSTREAM END WALL HAVING A CENTRAL OPENING AROUND THE AXIS OF SAID CASINGS, A RADIAL FLOW FAN ROTOR HAVING A BACK PLATE ADJACENT TO AND EXTENDING SUBSTANTIALLY PARALLEL TO SAID UPSTREAM WALL, SAID ROTOR HAVING A FRONT PLATE SPACED FROM SAID BACK PLATE AND HAVING FAN BLADES SUPPORTED BETWEEN SAID PLATES, A HUB ATTACHED TO SAID BACK PLATE, A SHAFT ATTACHED TO SAID HUB AND EXTENDING THROUGH SAID CENTRAL OPENING INTO SAID INNER CASING, BEARINGS IN SAID INNER CASING AROUND SAID SHAFT, AND HAVING AIR SUPPLY MEANS EXTENDING THROUGH SAID OUTER CASING INTO SAID INNER CASING, THE COMBINATION THEREWITH OF AUXILIARY FAN MEANS FOR DRAWING AIR THROUGH SAID SUPPLY MEANS INTO THE INTERIOR OF SAID INNER CASING AND SAID CENTRAL OPENING AND DISCHARGING SUCH AIR INTO SAID FAN BLADES, SAID AUXILIARY FAN MEANS COMPRISING PASSINGS IN SAID HUB HAVING AIR INLETS ADJACENT TO SAID SHAFT AND HAVING AIR OUTLETS SPACED FROM SAID SHAFT LARGER DISTANCES THAN SAID INLETS ARE SPACED FROM SAID SHAFT, AND SEALING MEANS FOR PREVENTING THE ESCAPE OF GAS FROM SAID ROTOR THROUGH SAID CENTRAL OPENING, SAID SEALING MEANS COMPRISING AN ANNULAR RING ATTACHED TO SAID UPSTREAM END WALL AROUND SAID CENTRAL OPENING, AND HAVING A FIRST PORTION CONVERGING TOWARDS SAID HUB AND A SECOND ANNULAR RING ATTACHED TO SAID ROTOR AROUND SAID AIR INLETS AND HAVING A PORTION AROUND AND SPACED FROM SAID FIRST PORTION.