Flowmeter

Claim 1

APPARATUS TO MEASURE FLUID FLOW THROUGH A PASSAGE COMPRISING A STRUCTURE ADAPTED TO BE POSITIONED WITHIN THE PASSAGE, PACKING MEANS EXTENDING OUTWARDLY FROM SAID STRUCTURE TO ENGAGE THE WALLS OF THE PASSAGE TO DIVIDE THE PASSAGE INTO FIRST AND SECOND REGIONS, FIRST CONDUIT MEANS CARRIED BY SAID STRUCTURE TO COMMUNICATE BETWEEN SAID FIRST AND SECOND REGIONS, SECOND CONDUIT MEANS CARRIED BY SAID STRUCTURE TO COMMUNICATE BETWEN SAID FIRST AND SECOND REGIONS, MEANS POSITIONED IN SAID FIRST CONDUIT MEANS TO INDICATE FLUID FLOW THROUGH SAID FIRST CONDUIT MEANS, A ROTABLE IMPELLER POSITIONED IN SAID SECOND CONDUIT MEANS, MEANS TO ROTATE SAID IMPELLER AT VARIABLE SPEEDS, SWITCHING MEANS COUPLED TO SAID IMPELLER SO THAT ROTATION OF SAID IMPELLER OPENS AND CLOSES SAID SWITCHING MEANS, AN ELECTRICAL CIRCUIT INCLUDING SAID CIRCUIT, A MEANS, A VOLTAGE SOURCE APPLIED ACROSS SAID CIRCUIT, A PULSE GENERATING CIRCUIT CONNECTED TO SAID FIRST-MENTIONED CIRCUIT SO THAT ELECTRICAL PULSES IN SAID FIRST-MENTIONED CIRCUIT ENERGIZE SAID PULSE GENERATING CIRCUIT, A VOLTAGE INTEGRATING CIRCUIT CONNECTED TO THE OUTPUT OF SAID PULSE GENERATING CIRCUIT, AND MEANS TO MEASURE THE OUTPUT OF SAID INTEGRATING CIRCUIT WHICH IS RESPRESENTATIVE OF THE FREQUENCY OF OPENING AND CLOSING OF SAID SWITCHING MEANS, SAID FREQUENCY BEING REPRESENTATIVE OF THE RATE OF FLUID FLOW BETWEEN SAID REGIONS WHEN THE INDICATED FLOW THROUGH SAID FIRST CONDUIT MEANS IN ZERO.