Flowmeter

Claim 2

Gauge for measuring the mass flow of a gas comprising means for producing a corona discharge of ions in response to high voltage pulses, at least two collecting electrodes for receiving said ions, means for measuring the difference in the number of ions reaching two of said electrodes, and electronic means for interrupting said measurement at variable intervals so that the length of time during which the measurement is carried out is less than the length of time between two successive high voltage pulses.

Claim 3

Gauge as claimed in claim 1 which comprises a function generator delivering an intermittent signal inversely proportional to time, a multiplier connected to the output of said function generator and to said difference-measuring means to render said measurement independent of the mobility of the ions produced.

Claim 4

Gauge as claimed in claim 1 in which said ion source is connected to a high voltage source through a diode.

Claim 5

Gauge as claimed in claim 1 in which said means for producing a corona discharge of ions comprises a conductive wire parallel to the direction of flow of the gas.

Claim 6

Gauge as claimed in claim 4 in which said collecting electrodes comprise cylinders coaxial with said wire.

Claim 7

Gauge as claimed in claim 4 in which said collecting electrodes consist of a resistive conductive wire helically wound about said ion-discharging wire.

Claim 8

Gauge as claimed in claim 4 in which said ion-discharging wire extends axially of said gauge and comprising a supplemental polarized electrode consisting of two axially spaced substantially identical cylinders inside said collecting electrodes, said cylinders being connected to means for maintaining them at the same potential.

Claim 9

Gauge as claimed in claim 5 which comprises an electrostatic screen in the immediate proximity of said collecting electrodes.

Claim 10

Gauge as claimed in claim 5 in which said collecting electrodes are cylinders the adjacent ends of which are provided with saw teeth, the teeth on one electrode being opposite the spaces between the teeth of the other electrode.

Claim 11

Gauge as claimed in claim 4 in which the conductive wire which constitutes the ion source is stretched between two conductive mandrels and the ends of said mandrels in contact with said wire are shaped to improve the linearity of response of the gauge.

Claim 12

Method of measuring the mass flow of a gas independently of the nature and purity of the gas, which method comprises the steps of producing a corona discharge to provide a uniformly distributed flux of ions travelling in an electrical field having equipotential surfaces substantially parallel to the direction of gas flow; measuring the difference in the currents produced on two distinct collecting electrodes beginning as soon as possible after the most rapidly moving ions have reached the collecting electrodes and at the latest at the moment at which the slowest ions have reached the collecting electrodes; and correcting the resulting measurement by a coefficient inversely proportional to time so that the final measurement is independent of the mobility of the ions.

Claim 13

Method of measuring the mass flow of a gas independently of the nature and purity of the gas, which method comprises the steps of producing a corona discharge to provide a uniformly distributed flux of ions travelling in an electrical field having equipotential surfaces substantially parallel to the direction of gas flow; measuring the difference in the currents produced on two distinct collecting electrodes beginning as soon as possible after the most rapidly moving ions have reached the collecting electrodes and at the latest at the moment at which the slowest ions have reached the collecting electrodes; and correcting the resulting measurement by a coefficient inversely proportional to time so that the final measurement is independent of the mobility of the ions.