Encoder wheel assembly and method for ascertaining an absolute angular position and a rotational direction

Patent metadata

Field	Value
Publication number	US-2019368902-A1
Application number	US-201716479983-A
Country	US
Kind code	A1
Filing date	Nov 20, 2017
Priority date	Jan 23, 2017
Publication date	Dec 5, 2019
Grant date	—

Abstract

The invention relates to an encoder wheel assembly ( ) for ascertaining an absolute angular position ( ) and a rotational direction ( ) of a rotor ( ), comprising the following: a first encoder wheel ( ) which is rotationally fixed to the rotor ( ) said first encoder wheel ( ) having a number n of teeth ( ) which are arranged in a uniformly spaced manner along the circumference of the encoder wheel; a second encoder wheel ( ) which is rotationally fixed to the first encoder wheel ( ) said second encoder wheel ( ) having the same number n of teeth ( ) as the first encoder wheel ( ) along the circumference of the encoder wheel, wherein the teeth ( ) of the second encoder wheel ( ) have an asymmetrical angular offset relative to the teeth ( ) of the first encoder wheel ( ) a first sensor ( ) which is designed to scan the first encoder wheel ( ); a second sensor ( ) which is designed to scan the second encoder wheel ( ); and a controller ( ) which is connected to the first sensor ( ) and the second sensor ( ) in a communicative manner, said controller being designed to ascertain the absolute angular position ( ) and the rotational direction ( ) on the basis of a binary signal ( ) which is derived from a first signal ( ) of the first sensor ( ) and a second signal ( ) of the second sensor ( ).

First claim

1 . An encoder ( 10 ) for determining an absolute angular position and a rotational direction of a rotor, comprising:
a first encoder wheel ( 12 a ) connected non-rotatably to the rotor, wherein the first encoder wheel ( 12 a ) comprises a number n of evenly spaced teeth ( 14 a ) arranged along its circumference; a second encoder wheel ( 12 b ) connected non-rotatably to the first encoder wheel ( 12 a ), wherein the second encoder wheel ( 12 b ) comprises the same number n of teeth ( 14 b ) as the first encoder wheel ( 12 a ) along its circumference, wherein the teeth ( 14 b ) of the second encoder wheel ( 12 b ) have an asymmetric angular offset to the teeth ( 14 a ) of the first encoder wheel ( 12 a ); a first sensor ( 16 a ) configured to sense the first encoder wheel ( 12 a ); a second sensor ( 16 b ) configured to sense the second encoder wheel ( 12 b ); a controller ( 17 ) communicatively connected to the first sensor ( 12 a ) and to the second sensor ( 12 b ), wherein the controller is configured to determine the absolute angular position and the rotational direction on the basis of a binary signal, wherein the binary signal is derived from a first signal of the first sensor ( 12 a ) and a second signal of the second sensor ( 12 b ).

2 . The encoder ( 10 ) as claimed in claim 1 , wherein the teeth ( 14 a ) of the first encoder wheel ( 12 a ) or the teeth ( 14 b ) of the second encoder wheel ( 12 b ) have the same shape.

3 . The encoder ( 10 ) as claimed in claim 1 , wherein the first sensor ( 16 a ) and the second sensor ( 16 b ) each comprise at least two sensor elements ( 22 a , 22 b , 22 c ), and wherein the first signal and the second signal are each difference signals ( 23 , 24 ) from measurement signals of the at least two sensor elements ( 22 a , 22 b , 22 c ) of the corresponding sensor ( 16 a , 16 b ).

4 . The encoder ( 10 ) as claimed in claim 1 , wherein the first sensor ( 16 a ) and the second sensor ( 16 b ) are designed configured to each generate at least two first signals and at least two second signals.

5 . The encoder ( 10 ) as claimed in claim 4 , wherein the controller ( 17 ) is configured to determine the rotational direction on the basis of the at least two first signals or of the at least two second signals.

6 . The encoder ( 10 ) as claimed in claim 1 , wherein the first sensor ( 16 a ) or the second sensor ( 16 b ) is a magnetic field sensor, and where accordingly the teeth ( 14 a ) of the first encoder wheel ( 12 a ) or the teeth ( 14 b ) of the second encoder wheel ( 12 b ) are ferromagnetic.

7 . A vehicle comprising an encoder arrangement ( 10 ) as claimed in claim 1 .

8 . A method for determining an absolute angular position and a rotational direction of a rotor, comprising the steps of:
a) receiving ( 2 ) a first signal from a first sensor ( 16 a ) that senses a first encoder wheel ( 12 a ) connected non-rotatably to the rotor, wherein the first encoder wheel ( 12 a ) comprises a number n of evenly spaced teeth ( 14 a ) arranged along its circumference; b) receiving ( 3 ) a second signal from a second sensor ( 16 b ) that senses a second encoder wheel ( 12 b ) connected non-rotatably to the first encoder wheel ( 12 a ), wherein the second encoder wheel ( 12 b ) comprises the same number n of teeth ( 14 b ) as the first encoder wheel ( 12 a ) along its circumference, wherein the teeth ( 14 b ) of the second encoder wheel ( 12 b ) have an asymmetric angular offset to the teeth ( 14 a ) of the first encoder wheel ( 12 a ); c) deriving ( 4 ) a binary signal from the first signal and the second signal; d) determining ( 5 ) the absolute angular position on the basis of the binary signal; and e) determining ( 8 ) the rotational direction on the basis of the binary signal.

9 . The method as claimed in claim 8 , wherein the first signal and the second signal are each difference signals ( 23 , 24 ) of measurement signals from at least two sensor elements ( 22 a , 22 b , 22 c ) of the corresponding sensor ( 16 a , 16 b ).

10 . The method as claimed in claim 8 , wherein at least two first signals and at least two second signals are accordingly received in step a) and step b).

11 . The method as claimed in claim 10 , wherein the rotational direction is determined in step e) on the basis of the at least two first signals or of the at least two second signals.

12 . The method as claimed in claim 8 , wherein a determination ( 6 ) of a starting angle is made on the basis of a test pulse method method in step d).

13 . (canceled)

14 . A non-transitory machine-readable storage medium on which a computer program is stored which carries out the method of claim 8 when executed.

15 . The encoder ( 10 ) as claimed in claim 6 , wherein the magnetic field sensor is a Hall sensor.

16 . The method as claimed in claim 8 , wherein a determination ( 6 ) of a starting angle is made on the basis of a current pulse method in step d).

Assignees

• Bosch Gmbh Robert

Inventors

• Utermoehlen Fabian
• Eckert Bernd
• Maur Marcel
• Letzgus Matthias
• Hanel Stephan
• Merkel Tino

Classifications

• G01D5/142

  using Hall-effect devices (measuring magnetic variables using Hall-effect or other galvanomagnetic devices G01R33/06) · CPC title

• G01D5/2497 Primary

  Absolute encoders (G01D5/2454 takes precedence) · CPC title

• G01D2205/771

  Toothed profiles · CPC title

• G01D2205/85

  Determining the direction of movement of an encoder, e.g. of an incremental encoder · CPC title