System and method for determining absolute angular position of a rotating member

• US 9,803,997 B2
• Filed: 07/26/2013
• Issued: 10/31/2017
• Est. Priority Date: 07/26/2013
• Status: Active Grant

• Current Assignee: BEI Sensors & Systems Company Incorporated (Schneider Electric SE)
• Original Assignee: BEI Sensors & Systems Company Incorporated (Schneider Electric SE)
• Inventors: Putinier, Rene
• Primary Examiner(s): ALLGOOD, ALESA M
• Application Number:
  US13/951,847
• Publication Number:
  US 20150028858A1
• Time in Patent Office: 1,558 Days
• Field of Search: 324202, 324205, 32420711-20725
• CPC Class Codes: G01D 2205/22 by converting the rotary movement into a linear movement
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G11B 25/043 using rotating discs
• CPC Class Codes: H02K 1/2733 Annular magnets
• CPC Class Codes: H02K 29/08 using magnetic effect devices, e.g. Hall-plates, magneto-resistors H02K29/12 takes precedence

Abstract

A sensor system determines an absolute angular position of a to-be-sensed rotating member. The sensor system may include a rotor with a first magnet coupled to the rotor and a shaft having threads thereon. The sensor system may further include a sleeve with a second magnet and threads complementary to the threads of a shaft. The sleeve may be configured to travel axially along the shaft as a function of rotation of the rotor. The sensor system may also include a first transducer configured to sense orientation of the first magnet and at least one second transducer configured to sense a location of the second magnet along the shaft. Through use of the sensor system, an absolute number of turns and, consequently absolute angular position, of the rotating member can be determined.

Claims

1. A sensor for determining absolute angular position of a rotating member, the sensor comprising:

a processor;

a rotor configured to rotate as a function of rotation of the rotating member, the rotor including a first magnet coupled to the rotor and a shaft having threads thereon;

a sleeve including a second magnet and threads complementary to the threads of the shaft, the sleeve configured to travel axially along the shaft as a function of rotation of the rotor;

a first transducer configured to sense orientation of the first magnet; and

a plurality of second transducers linearly disposed along a line that is adjacent and parallel to the shaft, wherein a combination of the plurality of second transducers are used to sense an axial location of the second magnet along the shaft when the sleeve, including the second magnet, travels axially along the shaft as a function of the rotation of the rotor, and wherein the processor determines a difference between signals received from at least two successive transducers of the plurality of second transducers to compensate for interference caused by the first magnet.

2. The sensor of claim 1, further comprising a complimentary retaining pair configured to cause the sleeve to travel axially along the shaft as a function of rotation of the rotor.

3. The sensor of claim 1, wherein the first transducer or the plurality of second transducers are selected from a group consisting of:

a Hall effect transducer, an optical transducer, a resistive transducer, and an inductive transducer.

4. The sensor of claim 1, further comprising a magnetic shield positioned between the first magnet and the second magnet.

5. The sensor of claim 1, wherein the processor is configured to convert output from the first transducer and the plurality of second transducers to determine a representation of an absolute angular position of the rotating member.

6. The sensor of claim 1, wherein the sleeve is coupled with a stopping bearing configured to hold the sleeve in association with the threads of the shaft in event of a runout to enable the sleeve to be reassociated with the shaft responsive to reverse turning of the rotor.

7. The sensor of claim 1, wherein the plurality of second transducers, includes a first portion of the plurality of second transducers being a function of a second number of rotor turns the sensor can count, a sensing length of the sensor, or a combination thereof.

8. The sensor of claim 7, wherein the first portion of the plurality of transducers is six transducers and the second number of turns the sensor can count is ten.

9. The sensor of claim 1, wherein the plurality of second transducers are mounted on a printed circuit board.

10. The sensor of claim 9, wherein the printed circuit board is a daughter printed circuit board that is mounted to a mother circuit board at a perpendicular angle, the first transducer being coupled to the mother circuit board.

11. A method for determining absolute angular position of a rotating member with a sensor, the method comprising:

rotating a rotor as a function of rotation of the rotating member, the rotor including a first magnet coupled to the rotor and a shaft having threads thereon;

travelling axially a sleeve along the shaft as a function of rotation of the rotor, the sleeve including a second magnet and threads complementary to the threads of the shaft;

sensing orientation of the first magnet at a first transducer; and

sensing an axial location of the second magnet along the shaft by a plurality of second transducers when the sleeve, including the second magnet, travels axially along the shaft as a function of the rotation of the rotor, wherein the plurality of second transducers are positioned linearly along a line adjacent and parallel to an axis of rotation of the shaft and wherein a processor determines a difference between signals received from at least two successive transducers of the plurality of second transducers to compensate for interference caused by the first magnet.

12. The method of claim 11, further comprising causing the sleeve to travel axially along the shaft as a function of rotation of the rotor by a complimentary retaining pair.

13. The method of claim 11, further comprising selecting the first transducer or the plurality of second transducers from a group including:

a Hall effect transducer, an optical transducer, a resistive transducer, and an inductive transducer.

14. The method of claim 11, further comprising positioning a magnetic shield between the first magnet and the second magnet.

15. The method of claim 11, further comprising converting, at the processor, output from the first transducer and the at least one second transducer to a generate a representation of an absolute angular position of the rotating member.

16. The method of claim 11, further comprising coupling the sleeve with a stopping bearing configured to hold the sleeve in association with the threads of the shaft in event of a runout to enable the sleeve to be reassociated with the shaft responsive to reverse turning of the rotor.

17. The method of claim 11, further comprising determining a first number of a plurality of transducers, as a function of a second number of rotor turns the sensor can count, a sensing length of the sensor, or a combination thereof, wherein the plurality of second transducers includes the first number of the plurality of transducers determined.

18. The method of claim 17, wherein the first number of the plurality of transducers determined is six transducers and the second number of turns the sensor can count is ten.

19. The method of claim 11, further comprising mounting the plurality of second transducers on a printed circuit board.

20. The method of claim 19, wherein the printed circuit board is a daughter printed circuit board that is mounted to a mother circuit board at a perpendicular angle, the first transducer being coupled to the mother circuit board.