Gas filtering apparatus

Claim 1

A GAS FILTERING UNIT COMPRISING, IN COMBINATION, A CASING HAVING A INLET CHAMBER WITH AN INLET FOR DUSTLADEN GAS, A FILTER CHAMBER AND AT LEAST ONE EXHAUST VENT FOR THE DISCHARGE OF GAS IN A FILTERED CONDITION; FILTER ELEMENTS SUPPORTED WITHIN SAID FILTER CHAMBER; A FAN COMPRISING A ROTARY IMPELLER AND A CASING THEREFOR MOUNTED WITHIN THE UNIT CASING BETWEEN THE INLET CHAMBER AND THE EXHAUST VENT FOR INDUCING GAS AND ACCOMPANYING DUST FROM A DUST SOURCE TO FLOW THROUGH THE FILTER ELEMENTS WHEREBY THE DUST IS SEPARATED FROM THE GAS STREAM, THE FINER DUST PARTICLES BEING RETAINED ON THE SURFACES OF THE FILTER ELEMENTS WHILST THE HEAVIER PARTICLES FALL AWAY FROM THE LATTER: A DUST CONTAINER LOCATED IN THE BASE OF THE UNIT FOR COLLECTING THE HEAVIER DUST PARTICLES; AN ELECTRIC MOTOR FOR DRIVING THE SAID FAN; SAID MOTOR HAVING A SHAFT COUPLED WITH THE FAN IMPELLER; A BOB WEIGHT HOUSING RIGIDLY SECURED UPON SAID MOTOR SHAFT SO AS TO ROTATE THEREWITH; THE EXTERNAL CIRCUMFERENTIAL SURFACE OF THE SAID HOUSING BEING BEVELLED; A CENTRIFUL CLUTCH HAVING AN OUTER PART CONNECTED TO SAID MOTOR SHAFT AND AN INNER PART CONNECTED TO A DRUM, A PLURALITY OF BOB WEIGHTS MOUNTED WITHIN SAID HOUSING FOR MOVEMENTS RADIALLY INWARDS AND OUTWARDS IN RESPONSE TO THE CENTRIFUGAL FORCE APPLIED THERETO, SAID WEIGHTS CONSTITUTING SAID OUTER PARTS OF THE CENTRIFUGAL CLUTCH; MEANS BIASSING THE SAID WEIGHTS INWARDS; A SHAKING MECHANISM INCLUDING A ROTARY DRIVE SHAFT OPERATIVELY CONNECTED TO SAID FILTER ELEMENTS FOR SHAKING THE FILTER ELEMENTS; A DRUM MOUNTED UPON SAID ROTARY DRIVE SHAFT AND CONSTITUTING THE INNER PART OF SAID CENTRIFUGAL CLUTCH; A FIXED BEARING HOUSING FOR SAID ROTARY DRIVE SHAFT, SAID BEARING HOUSING BEING OF CONICAL FORM AND PRESENTING AN EXTERIOR SURFACE COMPLEMENTING THAT OF THE BOB WEIGHT HOUSING WHEREBY THE SAID BEARING HOUSING FORMS THE APEX PORTION OF A COMPLETE CLUTCH ENCLOSURE OF CONICAL FORM WHICH INCLUDES THE BOB WEIGHT HOUSING AND IS LOCATED WITHIN THE CENTRAL PORTION OF THE FAN IMPELLER WITHIN THE BLADES THEREOF; THE ARRANGEMENT BEING SUCH THAT WHENEVER THE FAN MOTOR IS SWITCHED OFF AND THE ROTATIONAL SPEED THEREOF HAS PROGRESSIVELY FALLEN TO AN APPROPRIATE LEVEL THE BOB WEIGHTS WILL MOVE UNDER THE SAID INFLUENCE OF THE BIASSING MEANS INTO CONTACT WITH THE SURFACE OF THE DRUM TO COUPLE THE FAN MOTOR WITH THE SAID SHAKING MECHANISM, WHEREAS EACH TIME THE FAN MOTOR IS STARTED THE FILTER ELEMENTS WILL BE AUTOMATICALLY SHAKEN UNTIL THE MOTOR ATTAINS A ROTATIONAL SPEED AT WHICH THE BOB WEIGHTS MOVE OUTWARDS AWAY FROM THE DRUM AGAINST THE ACTION OF THE BIASSING MEANS TO DISENGAGE THE SHAKING MECHANISM FROM THE MOTOR.