Rotameter system with electrical read-out

Claim 2

A rotameter system adapted to produce an electrical signal which is proportional to flow rate, said system comprising: A. a primary element including a variable area flow tube through which flows the fluid whose rate is to be measured, and a float slideable along a vertical guide rod disposed within said tube, said float being raised and lowered to a degree depending on flow rate, and B. a linear displacement transducer operatively coupled to the upper end of said rod and including means to generate a torsional strain pulse at the position of the float, means at a fixed point coupled to said rod to receive said pulse, means to measure the time interval required for said torsional strain pulse generated at the float position to travel from the float along the rod to said fixed receiving point, and means to convert this interval into an electrical signal representative of the float position.

Claim 3

A system as set forth in claim 1, wherein said torsional strain pulse generating means is constituted by a permanent magnet embedded in said float, a magnetostrictive wire embedded in said rod, and a pulse generator which applies periodic current pulses to said wire, each creating a momentary field which interacts with a magnetic field produced by said permanent magnet embedded in said float, thereby imparting said torsional strain to said wire.

Claim 4

A system as set forth in claim 2, wherein said current pulses are produced by a quartz-crystal oscillator operating at a predetermined frequency.

Claim 5

A system as set forth in claim 2, wherein said means to receive the torsional strain pulses at the fixed receiving point is constituted by a torsional sensor to produce a receive pulse at a time displaced from the current pulse.

Claim 6

A system as set forth in claim 4, wherein the means to convert the time interval into an electrical signal includes a rectangular wave generator producing rectangular pulses whose duration is equal to the period between a current pulse and a received pulse, and means to integrate the rectangular pulses to produce an average D-C voltage whose level is proportional to the float position.

Claim 7

A system as set forth in claim 5, including means to maintain the amplitude of the rectangular pulses at a constant level.

Claim 8

A system as set forth in claim 5, further including an amplifier connected to the output of the integrating means to produce a current signal in a range proportional to the range in which the float is shifted from a minimum to a maximum position.

Claim 9

A system as set forth in claim 1, wherein said flow tube has a lateral inlet port and a lateral outlet port and said guide rod extends outside of said tube through the upper end thereof and is coupled to said transducer.

Claim 10

A system as set forth in claim 1, wherein said flow tube has an inlet at the lower end thereof and an outlet at the upper end thereof, said guide rod being supported coaxially within said tube by a spider one of whose spokes is coupled to said transducer.

Claim 11

A system as set forth in claim 1, wherein said flow tube has an inlet at the lower end thereof and an oulet of the upper end thereof, the upper end of said guide rod being bent and passing laterally outside of said tube to be coUpled to said transducer.

Claim 12

A rotameter system adapted to produce an electrical signal which is linearly proportional to flow rate, said system comprising: A. a primary including a variable area flow tube through which flows the fluid whose rate is to be measured, a float incorporating a permanent magnet slideable along a guide rod disposed within said tube, said guide rod having a magnetostrictive wire enclosed therein, said float being raised and lowered on said rod to a degree depending on flow rate whereby the magnetic field produced by said magnet intercepts said wire at a point depending on the float position. B. a linear displacement transducer operatively coupled to the upper end of the wire in said rod and including a pulse-to-voltage converter to apply current pulses into said wire producing a momentary field that interacts with said magnetic field to produce a torsional strain in said wire, thereby causing a strain pulse to be launched at the float position whose arrival is detected at the upper end of the wire to produce a receive pulse, the interval between the current pulse and the received pulse being measured to provide said electrical signal proportional to flow rate.

Claim 13

A rotameter system adapted to produce an electrical signal which is linearly proportional to flow rate, said system comprising: A. a primary including a variable area flow tube through which flows the fluid whose rate is to be measured, a float incorporating a permanent magnet slideable along a guide rod disposed within said tube, said guide rod having a magnetostrictive wire enclosed therein, said float being raised and lowered on said rod to a degree depending on flow rate whereby the magnetic field produced by said magnet intercepts said wire at a point depending on the float position. B. a linear displacement transducer operatively coupled to the upper end of the wire in said rod and including a pulse-to-voltage converter to apply current pulses into said wire producing a momentary field that interacts with said magnetic field to produce a torsional strain in said wire, thereby causing a strain pulse to be launched at the float position whose arrival is detected at the upper end of the wire to produce a receive pulse, the interval between the current pulse and the received pulse being measured to provide said electrical signal proportional to flow rate.

Claim 14

A system as set forth in claim 11, wherein said rod is formed by a Teflon-coated conductive tube incorporating said wire.

Claim 15

A system as set forth in claim 11, wherein said wire is formed of a nickel-cadmium alloy.