Raytheon Company

Alliedsignal Inc.

Gerald W Meyer

Steven D Jacob

Zvi Shkedi

James S Lepkowski

Fares Najjar

Richard D Ross

Karl S Pogany, Jr

A method of solenoid valve control includes measuring voltage across the solenoid valve and current through the solenoid valve, and using the results to aid in controlling the solenoid valve. For instance, one or both of the measured values may be used to determine when actual engagement of the solenoid valve occurs. An initial lower voltage and lower current can be used, and then as conditions change, the changes in condition can be accounted for by increasing voltage and current to maintain the desired response time of the solenoid valve. By measuring and controlling voltage and current less of a margin can be used, both in setting voltage/current levels and in selecting the time over which a pull voltage/current is utilized. This reduces the wasted energy in the system, as well as reducing the temperature rise in the solenoid valve.

Method of controlling solenoid valve

A capacitive ratioing oscillator circuit utilizing a prior art pressure capsule, but through modification of the state variable oscillator circuit achieves a digital output which varies with the square root of the capacitance ratio C35 C.sub.p /C.sub.r. In this sensor the dielectric constant of the pressure media is measured in time with the pressure difference measurement. The oscillator includes a differentiator-inventor step herein each of capacitors C.sub.r and C.sub.p are connected to a common point and resistors are connected in parallel with each of said capacitors and with the common point connected to the inverting terminal of a first operational amplifier, a feedback line is connected from the output of the operational amplifier to the second resistor opposite the common point, first and second integrator circuits are connected to the output of said operational amplifier, a limit circuit is connected across the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit to the input of the inverter stage.

Capacitive pressure transducer system

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Tucson, AZ, United States of America

Gerald W Meyer