# US 7,768,257 B2 · Systems and methods for determining the position of an electrical solenoid

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- Number: US 7,768,257 B2
- Document ID: US7768257B2
- Status: Granted
- Kind: B2
- Application number: 12/123,267
- Filed: 2008-05-19
- Published: 2008-11-20
- Granted: 2010-08-03
- Earliest claimed: 2007-05-17
- Assignees: Alcotek, Inc.
- Inventors: Keith Lueck
- Web page: https://patentgrep.com/patent/US7768257B2

## CPC

- G01B 7/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B7/30 takes precedence)
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

Provided herein are systems and methods which use the solenoid itself to sense the position of the armature within the solenoid, and therefore to determine the position of the solenoid's armature, and or any related devices whose movement is dependent on the armature's movement. Specifically, a system in which the change in self-induction that occurs when the armature moves relative to the solenoid coil is used to detect the location of the armature.

## Claims

### Claim 1

A method for determining the position of an armature in a solenoid, the method comprising:
providing a solenoid having an armature and a coil;
applying a current pulse to said coil;
obtaining a back-emf waveform from said solenoid;
integrating said back-emf waveform; and
determining a location of said armature from said integrated back-emf waveform.

### Claim 2 (depends on 1)

The method of claim 1 further comprising:
gating said back-emf waveform prior to said integrating.

### Claim 3 (depends on 1)

The method of claim 1 wherein said method will be used in a latched solenoid drive scheme.

### Claim 4 (depends on 1)

The method of claim 1 wherein said method will be used in a non-latched solenoid drive scheme.

### Claim 5 (depends on 1)

The method of claim 1 wherein said method will be integrated into a drive mechanism for said solenoid.

### Claim 6 (depends on 1)

The method of claim 1 wherein said current pulse is a square pulse.

### Claim 7 (depends on 1)

The method of claim 1 wherein said current pulse is insufficient to move said armature relative to said coil.

### Claim 8

A solenoid and control circuit comprising:
a coil;
an armature within said coil;
means for generating a current pulse in said coil;
means for detecting a back-emf waveform generated by said coil in response to said pulse;
means for integrating said back-emf waveform; and
means for using said integrated back-emf waveform to determine the location of said armature relative to said coil.

### Claim 9 (depends on 8)

The circuit of claim 8 wherein means for using is integrated into drive electronics for said solenoid.

### Claim 10 (depends on 8)

The circuit of claim 8 wherein said means for generating generates a square wave pulse input.

### Claim 11 (depends on 8)

The circuit of claim 8 wherein circuit includes means for gating said back-emf waveform.

### Claim 12

A system for determining the position of a solenoid, the system comprising:
a solenoid including a coil and an armature within said coil;
a current generator for generating a current in said coil;
a processor for inducing said current generator to provide a current pulse in said coil and;
an integration circuit integrating said back-emf waveform; and
a processor for utilizing said integrated back-emf waveform to determine a location of said armature relative to said coil.

### Claim 13 (depends on 12)

The system of claim 12 wherein said current generator, said detector, and said processors are integrated into drive electronics for said solenoid.

### Claim 14 (depends on 12)

The system of claim 12 wherein said pulse processor induces a square wave pulse.

### Claim 15 (depends on 12)

The system of claim 12 further comprising, a gate circuit.

### Claim 16 (depends on 15)

The system of claim 15 wherein said current generator, said detector, said gate circuit, and said processors are integrated into drive electronics for said solenoid.

### Claim 17 (depends on 15)

The system of claim 15 wherein said pulse generator, said detector, said integration circuit, and said gate circuit are part of an integrated circuit.

### Claim 18 (depends on 12)

The system of claim 12 wherein said processor for inducing and said processor for utilizing are the same processor.