# US 2021/0344265 A1 · Brushless electrical machine

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- Number: US 2021/0344265 A1
- Document ID: US20210344265A1
- Status: Published application
- Kind: A1
- Application number: 17/280,652
- Filed: 2018-12-18
- Published: 2021-11-04
- Earliest claimed: 2018-12-18
- Assignees: Robert Bosch GmbH
- Applicants: Robert Bosch GmbH
- Inventors: Christian Binder; Oliver Fuchs
- Web page: https://patentgrep.com/patent/US20210344265A1

## CPC

- H02K 29/08: using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence)
- H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements
- H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information
- H02P 2203/03: Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A brushless electrical machine, in particular, a brushless d.c. motor, having a housing, at least one rotor, which is positioned on a shaft rotationally mounted in the housing, and a stator attached to the housing; the rotor being assigned a rotor position detection device, which operates contactlessly and includes a multipole magnetic ring positioned on the shaft in a rotatably fixed manner and at least one sensor, which is sensitive to magnetic fields and is attached to the housing radially with respect to the outer circumference of the magnetic ring. The number of pole pairs of the rotor and the number of pole pairs of the magnetic ring are coprime.

## Claims

### Claim at position 1

1-10. (canceled)

### Claim 11

A brushless electrical machine, comprising:
a housing;
at least one rotor, which is positioned on a shaft rotationally mounted in the housing;
a stator attached to the housing; and
a rotor position detection device, the rotor being assigned the rotor position detection device, the rotor position detection device being configured to operate contactlessly and includes a multipole magnetic ring positioned on the shaft in a rotatably fixed manner, and at least one sensor, which is sensitive to magnetic fields and is attached to the housing radially with respect to an outer circumference of the magnetic ring;
wherein a number of pole pairs of the rotor and a number of pole pairs of the magnetic ring are coprime.

### Claim 12 (depends on 11)

The brushless electrical machine as recited in claim 11, wherein the brushless electrical machine is a brushless d.c. motor.

### Claim 13 (depends on 11)

The brushless electrical machine as recited in claim 11, wherein the number of pole pairs of the rotor is 4.

### Claim 14 (depends on 11)

The brushless electrical machine as recited in claim 11, wherein the number of pole pairs of the magnetic ring is 5.

### Claim 15 (depends on 11)

The brushless electrical machine as recited in claim 11, wherein the number of pole pairs of the magnetic ring determines a number of angular segments of the rotor position detection device.

### Claim 16 (depends on 11)

The brushless electrical machine as recited in claim 11, further comprising:
a control unit configured to ascertain an angular segment of the magnetic ring as a function of a signal of the sensor, and to determine an angle of rotation as a function of the ascertained angular segment.

### Claim 17 (depends on 16)

The brushless electrical machine as recited in claim 16, further comprising a monitoring device, wherein to ascertain the angular segment, the control unit is configured to induce a first current in the stator to turn the rotor in a first direction of rotation, into a first angular segment, and wherein the monitoring device is configured to monitor the rotor for an angular motion.

### Claim 18 (depends on 17)

The brushless electrical machine as recited in claim 17, wherein the monitoring device is configured to monitor the angular motion for a direction of rotation.

### Claim 19 (depends on 17)

The brushless electrical machine as recited in claim 17, wherein the control unit is configured to induce a second current in the stator to turn the rotor two angular segments in a direction of rotation opposite to the first direction of rotation, and the monitoring device is configured to monitor the rotor for the angular motion.

### Claim 20 (depends on 19)

The brushless electrical machine as recited in claim 19, wherein the monitoring device is configured to monitor the angular motion for a direction of rotation.

### Claim 21 (depends on 20)

The brushless electrical machine as recited in claim 20, wherein the control unit is configured to induce a third current in the stator, to turn the rotor one angular segment in the first direction of rotation, when the monitoring device has detected that the rotor turned in the first direction of rotation, due to the second current.