Fan equipment

Claim 1

A POWER VENTILATOR FOR EFFECTING THE SIMULTANEOUS FLOW OF GAS IN OPPOSITE PARALLEL DIRECTIONS THROUGH TWO ADJACENT PATHS THEREIN, COMPRISING: A CASING HAVING A SUBSTANTIALLY CIRCULAR CROSS SECTION AND BEING OPEN AT THE AXIAL ENDS THEREOF; AN INTERMEDIATE, SUBSTANTIALLY CYLINDRICAL WALL STRUCTURE COAXIALLY DISPOSED WITHIN AND SPACED FROM SAID CASING TO DEFINE A FIRST ANNULAR PASSAGEWAY EXTENDING AXIALLY OF SAID CASING, SAID WALL STRUCTURE INCLUDING FIRST AND SECOND, AXIALLY SPACED WALL MEMBERS; AN INNER, SUBSTANTIALLY CYLINDRICAL WALL STRUCTURE DISPOSED COAXIALLY WITHIN AND RADIALLY SPACED FROM THE INTERMEDIATE WALL STRUCTURE TO DEFINE THEREWITH A SECOND ANNULAR PASSAGEWAY EXTENDING AXIALLY OF SAID INTERMEDIATE STRUCTURE AND BEING INDEPENDENT OF SAID FIRST PASSAGEWAY, SAID INNER WALL STRUCTURE INCLUDING FIRST AND SECOND AXIALLY SPACED WALL MEMBERS; AN AXIAL FLOW IMPELLER DISPOSED BETWEEN THE FIRST AND SECOND WALL MEMBERS OF SAID INNER WALL STRUCTURE AND OF SAID INTERMEDIATE WALL STRUCTURE, SAID IMPELLER HAVING A FIRST SET OF BLADES LOCATED WITHIN SAID SECOND ANNULAR PASSAGEWAY, SAID BLADES BEING ARRANGED AND SHAPED TO EFFECT A FLOW OF GAS THROUGH SAID SECOND ANNULAR PASSAGEWAY IN ONE AXIAL DIRECTION, SAID IMPELLER HAVING A SECOND SET OF BLADES LOCATED WITHIN SAID FIRST ANNULAR PASSAGEWAY, SAID SECOND SET OF BLADES BEING ARRANGED AND SHAPED TO EFFECT THE FLOW OF GAS THROUGH SAID FIRST ANNULAR PASSAGEWAY IN THE OPPOSITE AXIAL DIRECTION, SAID SECOND SET OF BLADES BEING OF GREATER RADIAL EXTENT THAN, AND HAVING ABOUT ONE HALF OF THE AXIAL EXTENT OF, SAID FIRST SET OF BLADES, AND SAID FIRST SET OF BLADES BEING CAPABLE OF DEVELOPING DURING ROTATION OF SAID IMPELLER AT SUBSTANTIALLY NORMAL OPERATING SPEED, A HIGHER TOTAL PRESSURE THAN THE TOTAL PRESSURE DEVELOPED BY THE SECOND SET OF BLADES; AND MEANS SUPPORTING SAID IMPELLER FOR ROTATION COAXIALLY WITHIN SAID CASING WHEREBY THE GAS FLOW IS EFFECTED, SAID SUPPORT MEANS BEING DISPOSED WITHIN AND SECURED TO SAID INNER WALL STRUCTURE.