Ion-drag flowmeter
AssigneeGeneral Motors Corporation
InventorsGerard W. Malaczynski, Thaddeus Schroeder
Life of this patent
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Abstract
In an ion-drag flowmeter, an improvement is provided for alleviating the problem that the deflection of the ion stream may be altered dependent upon the concentration of polar molecules due to changes in the mobility of the ions caused by the clustering of polar molecules to the ions as result of collisions therebetween in which the polar molecules adhere to the ions. The improvement involves keeping the ambient electric field sufficiently weak that the clustering of polar molecules to the ions approaches a dynamic equilibrium in which thermal effects dominate electric field effects in promoting collisions between polar molecules and ions such that the mobility of the ions is substantially stabilized independent of the concentration of polar molecules.
Claims15
In a method for measuring the flow rate of a gas including a variable concentration of polar molecules, the method involving the steps of:
- generating a stream of ions that is deflected by the gas flow wherein the amount of deflection is dependent upon the concentration of polar molecules in the gas, and
- sensing the degree of deflection of the ion stream to provide a measure of the gas flow rate,
- an improvement comprising the additional step of:
- keeping the ambient electric field sufficiently weak that the deflection of the ion stream is rendered independent of the concentration of polar molecules in the gas.
In apparatus for measuring the flow rate of a gas including a variable concentration of polar molecules, the apparatus comprising:
- means for producing a corona discharge to generate a stream of ions that is deflected by the gas flow wherein the amount of deflection is dependent upon the concentration of polar molecules in the gas, and
- means for collecting the deflected ions to sense the degree of deflection of the ion stream as a measure of the gas flow rate,
- an improvement comprising:
- means for controlling the corona discharge so as to maintain the ambient electric field low enough that the deflection of the ion stream is rendered independent of the concentration of polar molecules in the gas.
Dependencies are inferred from the claim text.