Inductive divider position sensor with fixed and variable impedance inductors
AssigneeEldec Corporation
InventorBernard J. Burreson
Life of this patent
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Abstract
Disclosed is an inductive divider sensor that comprises a variable inductor (12) connected in series with a fixed inductor (16) between a source of AC voltage and ground. A target element (18) is moved by an object whose position is to be sensed along an axis that extends through the variable inductor thereby changing its impedance. The impedance of the variable inductor is designed to vary such that the voltage taken at a node where the variable inductor and fixed inductor are connected varies according to a predetermined linear output signal.
Claims16
An inductive position sensor that, when coupled to a source of driving voltage, produces an output signal that is related to a position of an object in accordance with a predetermined mathematical formula comprising:
- a first inductor having a fixed impedance;
- a variable inductor connected in series with the first inductor, the unconnected end of one of the first and variable inductors suitable for being coupled to a source of driving voltage;
- and
- a target element including means for coupling the target element to the object whose position is to be indicated, the target element being movable along an axis that extends into the variable inductor, wherein the variable inductor includes a number of serially connected coils, each coil having a number of windings, N, that are wound such that the variable inductor has an impedance that varies with the position of the target element so that the ratio of the fixed impedance and the variable impedance divides the driving voltage to produce an output signal that varies according to a predetermined mathematical formula, said output signal being produced at a node that joins the first inductor and the variable inductor.
An inductive sensor for producing an output signal that is indicative of a position of an object in accordance with a predetermined mathematical formula, comprising:
- a source of a driving voltage;
- a first inductor having a fixed inductance;
- a variable inductor connected in series with the first inductor;
- and
- a target element including means for coupling the target element to the object whose position is to be indicated, wherein the target element is movable along an axis that extends through the variable inductor by the object, wherein the first inductor and the variable inductor are connected in series between the source of the driving voltage and a ground potential and wherein the variable inductor comprises a plurality of coils each having a number of turns, N, wherein the number of turns, N, is selected so that the variable inductor has an impedance that varies as the target element is moved such that the ratio of the fixed impedance and the impedance of the variable inductor produces an output signal at a node that joins the first and variable inductors that varies according to a predetermined mathematical formula.
A method for determining the position of an object with an inductive divider sensor that produces an output signal that varies according to a predetermined mathematical formula, the method comprising the steps of:
- coupling a target element to the object whose position is to be sensed so that as the object moves, the position of the target element is moved along an axis that extends into the inductive divider sensor, wherein the inductive divider sensor comprises:
- a first inductor having a fixed impedance;
- a variable inductor connected in series with the first inductor, the variable inductor including a plurality of serially connected coils, each having a number of windings, N, that are selected such that the variable inductor has an impedance that varies with the position of the target element, the impedance of the variable inductor is selected such that the ratio of the fixed impedance and the variable impedance produces an output voltage at a node where the first and the variable inductors are connected that varies according to a predetermined mathematical formula;
- sensing the output voltage;
- and
- using the output voltage in the predetermined mathematical formula to determine the position of the object.
Dependencies are inferred from the claim text.