초록 ▼

A fluid thermal mass flow meter including a composite flow tube having four tubular segments of high thermal conductivity formed in a length of tube made of a material having a relatively low thermal conductivity, a thin film element formed on the surface of and extending around each of the four tub

A fluid thermal mass flow meter including a composite flow tube having four tubular segments of high thermal conductivity formed in a length of tube made of a material having a relatively low thermal conductivity, a thin film element formed on the surface of and extending around each of the four tubular segments, circuitry for incorporating the elements into a bridge circuit, and a housing for containing the flow tube, elements, and circuitry.

대표청구항 ▼

[ What is claimed is:] [1.] A thermal mass flow meter for measuring fluid flow rate comprising:a housing;a composite sensor tube of a first material having a first thermal conductivity and including segments of a second material having a second thermal conductivity greater than said first conductivi

[ What is claimed is:] [1.] A thermal mass flow meter for measuring fluid flow rate comprising:a housing;a composite sensor tube of a first material having a first thermal conductivity and including segments of a second material having a second thermal conductivity greater than said first conductivity, the tube and segments being attached together for conducting fluid the mass flow rate of which is to be measured, and having at least two resistive thin film elements formed on said segments of said second material, said sensor tube being thermally sunk to said housing in substantially all surface areas except those upon which the elements are located, the elements having means for allowing selection and trimming of resistance associated therewith during assembly of the thermal mass flow meter;a source providing constant current; andelectrical means for coupling constant current from said source to said elements and for measuring voltage change across said elements, the voltage change being representative of temperature change in the elements and proportional to the fluid mass flow rate.