# US 10,119,838 B2 · Method for identifying the position of a rotor of an electric motor, target for determining the position of a rotor of the electric motor and electric motor

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- Number: US 10,119,838 B2
- Document ID: US10119838B2
- Status: Granted
- Kind: B2
- Application number: 15/303,875
- Filed: 2015-04-20
- Published: 2017-02-09
- Granted: 2018-11-06
- Earliest claimed: 2014-04-30
- Assignees: Schaeffler Technologies AG & Co. KG
- Applicants: Schaeffler Technologies AG & Co. KG
- Inventors: Markus Dietrich; Jurgen Gerhart
- Web page: https://patentgrep.com/patent/US10119838B2

## CPC

- G01D 5/24: by varying capacitance
- G01D 5/145: {influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06)}
- G01D 5/20: by varying inductance, e.g. by a movable armature
- G01D 5/2216: {by a movable ferromagnetic element, e.g. a core}
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

The invention relates to a method for identifying the position of a rotor of an electric motor, in which method a target arranged on a rotor is sensed using a sensor. In a method which can be carried out cost-effectively and nevertheless delivers highly accurate sensor signals, a rotational movement of the rotor is detected using an inductive or a capacitive sensor.

## Claims

### Claim 1

A target for determining a position of a rotor, comprising a geometric shape that is unambiguous over a rotation of the rotor and is scannable using a sensor, and
an electrically conductive material defines the unambiguous geometric shape and is arranged on a substrate.

### Claim 2 (depends on 1)

The target according to claim 1, wherein an electrically non-conductive geometric shape partially covers the substrate.

### Claim 3 (depends on 2)

The target according to claim 2, wherein a radial extent of the electrically non-conductive unambiguous geometric shape is inversely proportional to a radial extent of the defined unambiguous geometric shape about an axis of rotation of the rotor.

### Claim 4 (depends on 2)

The target according to claim 2, wherein the electrically non-conductive geometric shape is unambiguous.

### Claim 5 (depends on 1)

The target according to claim 1, wherein the geometric shape is embodied as an Archimedean screw.

### Claim 6 (depends on 1)

An electric motor, comprising a rotor moving at a rotor shaft, on which the target according to claim 1 is arranged in a torque-proof fashion, a sensor which scans the target, the target is arranged at an axial end face of the rotor shaft, and the sensor is aligned axially in reference to the rotor shaft towards the axial end face.

### Claim 7 (depends on 6)

The electric motor according to claim 6, wherein the sensor is embodied as an inductive or capacitive sensor.

### Claim 8 (depends on 1)

The target according to claim 1, wherein the substrate is an axial end face of the rotor.

### Claim 9 (depends on 1)

The target according to claim 1, wherein the defined unambiguous geometric shape is two dimensional.

### Claim 10 (depends on 1)

A system for determining a position of a rotor, comprising
the target of claim 1, wherein the unambiguous geometric shape comprises a first three-dimensional shape extending along an axis of rotation of the rotor, and a second-three dimensional shape extending along an axis of rotation of the rotor;
a first sensor head being adapted to detect a distance between the first three-dimensional shape and the first sensor head that changes due to a rotary motion of the rotor; and
a second sensor head being adapted to detect a distance between the second three-dimensional shape and the second sensor head that changes due to the rotary motion of the rotor.

### Claim 11 (depends on 10)

The system according to claim 10, wherein the first three-dimensional geometric shape and the second three-dimensional shape are both unambiguous over a rotation of the rotor.

### Claim 12 (depends on 10)

The target according to claim 10, wherein the first three-dimensional shape is embodied as a helix, having a first pitch continuously or gradually increasing or decreasing within an angle of 360°.

### Claim 13 (depends on 12)

The target according to claim 12, wherein the second three-dimensional shape is embodied as a helix, having a second pitch continuously or gradually increasing or decreasing within an angle of 360°, wherein the second pitch is opposite the first pitch.

### Claim 14 (depends on 10)

The target according to claim 10, wherein the second three-dimensional shape is inverse to the first three-dimensional shape.