Flow-responsive apparatus
AssigneeOnicon, Inc.
InventorParis H. Wiley
Life of this patent
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Abstract
The disclosed flow monitoring apparatus has a flow-varied sensing capacitance and an inductor in a series-resonant circuit that modulates the frequency of an oscillator. In one apparatus, the sensing capacitance comprises a flow-activated vaned rotor whose blades sweep past a very small capacitive sensing electrode, for monitoring flow rates. In other apparatus a flow-activated blade is biased to remain opposite a very small capacitive sensing electrode, to provide on/off flow indication.
Claims27
Apparatus for monitoring the flow of fluid, including an oscillator having frequency-modulating means including an inductive impedance and a capacitive impedance connected to each other as a series circuit having opposite-end connections and a common junction that only connects said impedances to each other, said oscillator including an amplifier and a frequency-determining feedback network, said series circuit constituting a component part of said feedback network and connected in said network at said opposite-end connections, said capacitive impedance including a flow sensor having a sensing capacitive electrode and flow-activated means coacting with said sensing capacitive electrode for modifying the capacitance of said capacitive impedance, said apparatus having significant stray as a shunt capacitance between said opposite-end connections of said series circuit, said series circuit thus comprising a series/parallel resonant circuit having a series-resonant frequency Fs and a parallel-resonant frequency Fp, the network being proportioned for causing oscillation at a frequency between Fs and Fp for at least part of the range of movement of the flow-responsive device.
Flow monitoring apparatus including an impedance network and an amplifying device connected to each other, said network and said amplifying device comprising an oscillator, said impedance network including inductance means and variable capacitance means connected as a series circuit for providing control to the frequency of the oscillator, said variable capacitance means including at least one sensing capacitive electrode and a flow-responsive device movable relative to said sensing electrode for modifying the capacitance of said capacitance means and thereby modifying the frequency of the oscillator, said series circuit having parallel capacitance at least part of which is in the form of stray capacitance, the series circuit having a series-resonant frequency Fs and a parallel-resonant frequency Fp higher than Fs, the network being proportioned for causing oscillation of the oscillator at a frequency between Fs and Fp for at least part of the range of movement of the flow-responsive device.
Flow sensing apparatus comprising inductance means and variable capacitance means connected as a series circuit, said series circuit having shunt capacitance and having a series-resonant frequency Fs and a parallel resonant frequency Fp, said variable capacitance means including at least one sensing electrode and a flow-responsive device variably cooperating with said sensing electrode for varying the capacitance said capacitance means, an amplifier, and a circuit network incorporating said series circuit connected to the amplifier to constitute an oscillator whose frequency is dependent on the relationship of said flow-responsive device to said sensing electrode, said network being proportioned so that said series circuit acts as an inductive component in the range of operation of the oscillator between Fs and FP.
Flow responsive apparatus including a frequency modulated oscillator having an amplifier and a frequency-controlling network connected to the amplifier, said frequency controlling network including an inductor and a variable capacitor, said inductor having first and second terminals and said variable capacitor including a localized sensing electrode and means constituting a companion electrode, said capacitor having flow-actuated means for varying the capacitance between said electrodes, means mounting said inductor and said capacitor with said first terminal in close proximity to said sensing electrode, and a conductor connecting said first terminal of the inductor directly to said sensing electrode, said second terminal of the inductor and said companion electrode forming opposite-end terminals of a series circuit, and said opposite-end terminals of said series circuit having respective connections which incorporate the series circuit in the network, said series circuit having significant parallel capacitance at least part of which is in the form of stray capacitance, the series circuit having a series-resonant frequency Fs and a parallel-resonant frequency Fp higher than Fs, the network being proportioned for causing oscillation of the oscillator at a frequency between Fs and Fp for at least part of the range of movement of the flow-responsive device.
Dependencies are inferred from the claim text.