Method and apparatus for monitoring armature position in direct-current solenoids
AssigneeMartin Marietta Energy Systems, Inc.
InventorsJohn C. Moyers, Howard D. Haynes
Life of this patent
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Abstract
A method for determining the position of an armature of a dc-powered solenoid. Electrical circuitry is provided to introduce a small alternating current flow through the coil. As a result, the impedance and resistance of the solenoid coil can be measured to provide information indicative of the armature's position.
Claims20
An apparatus for continuously monitoring armature position throughout the entire stroke length of a d.c. solenoid electrically coupled to a power source for supplying a d.c. voltage to a coil of the solenoid comprising:
- means for continuously supplying a continuous a.c. current signal to the solenoid coil during eneraization and deenergization of the coil with a d.c. current;
- means for continuously measuring a.c. and d.c. current flowing through the solenoid coil and a.c. and d.c. voltage across the solenoid coil;
- and
- means for determining impedance of the solenoid coil based on the measured values of a.c. current and voltage, the impedance varying in accordance to a position of the solenoid armature.
A method for continuously monitoring armature position throughout the entire stroke length of a d.c. solenoid electrically coupled to a power source for supplying a d.c. voltage to a coil of the solenoid comprising the steps of:
- continuously supplying a continuous a.c. signal to the solenoid coil during deenergization and energization of the solenoid coil with a d.c. current;
- continuously measuring a.c. and d.c. current flowing through the solenoid coil and a.c. and d.c. voltage across the solenoid coil;
- and
- determining the impedance of the solenoid coil based on the measured values of a.c. current and voltage, the impedance varying in accordance to a position of the solenoid armature.
An apparatus for monitoring operation of a d.c. solenoid having a coil and an armature movable through a stroke length between operative positions in response to energization and deenergization of the coil, the apparatus comprising:
- an a.c. current source selectively coupled to a power circuit of the solenoid to provide a continuous a.c. current, the a.c. current having a value which varies in accordance with the position of the armature;
- a d.c. current source selectively coupled to the power circuit to energize the solenoid coil with d.c. current;
- and
- a current detector coupled to the power circuit for continuously measuring a.c. current when the solenoid coil is energized and deenergized to move the armature between the operative positions through the stroke length,
- wherein changes in the measured a.c. current correspond to variations in armature position.
Dependencies are inferred from the claim text.