Position sensor and assembly

• US 20060087316A1
• Filed: 10/22/2004
• Published: 04/27/2006
• Est. Priority Date: 10/22/2004
• Status: Active Grant

• Current Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust), Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Sebastian, Tomy, Islam, Mohammad S., Mielke, Matthew
• Granted Patent: US 7,307,416 B2
• Time in Patent Office: Days
• US Class Current: 324/207.250
• CPC Class Codes: G01D 2205/77 Specific profiles
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06

Abstract

Disclosed herein, in an exemplary embodiment, is a position sensor assembly including a circular-shaped or rhombus-shaped magnet and at least one magnetic flux density sensor, such as a Hall effect sensor, wherein rotation of the magnet is detected by the at least one sensor. The magnet may be positioned coaxially with the longitudinal axis of a rotor shaft of a motor and provided within a support. A position extraction algorithm may be employed using the output from the sensors to detect the position of the rotor shaft.

Claims

1. A position sensor assembly comprising:

a rhombus-shaped magnet; and

at least one magnetic flux density sensor, wherein rotation of the rhombus-shaped magnet is detected by the at least one magnetic flux density sensor.

2. The position sensor assembly of claim 1 wherein the at least one magnetic flux density sensor includes three Hall sensors A, B, and C positioned 120 degrees apart from each other about a circular pattern circumscribed around the rhombus-shaped magnet, and wherein position information is extracted by measuring output signals V from the Hall sensors A, B, C, and employing the following algorithm to determine position θ

at different intervals;

3. The position sensor assembly of claim 1 wherein the rhombus-shaped magnet is magnetized through its major axis.

4. The position sensor assembly of claim 1 further comprising a circuit board holding the at least one magnetic flux density sensor.

5. The position sensor assembly of claim 1 further comprising a circular magnetic shield surrounding the rhombus-shaped magnet.

6. The position sensor assembly of claim 1 wherein the rhombus-shaped magnet is rotatable coaxially with a motor shaft.

7. The position sensor assembly of claim 1 wherein the at least one magnetic flux density sensor includes three Hall sensors spaced 120 degrees apart from each other about a circular pattern circumscribed around the rhombus-shaped magnet.

8. The position sensor assembly of claim 7 wherein, within every 60 degree interval of the circular pattern, absolute value of a redundant signal that is not used for position estimation is greater than or equal to summation of absolute value of working signals.

9. A motor position sensor assembly comprising:

a rotor shaft of a motor, the shaft having a longitudinal axis;

a rhombus-shaped magnet positioned coaxially with the longitudinal axis of the shaft, wherein the rhombus-shaped magnet is rotatable with the shaft; and

,

at least one magnetic flux density sensor, wherein rotation of the rhombus-shaped magnet is detected by the at least one magnetic flux density sensor.

10. The motor position sensor assembly of claim 9 wherein the rhombus-shaped magnet is magnetized through its major axis.

11. The motor position sensor assembly of claim 9 wherein the at least one magnetic flux density sensor includes three Hall sensors spaced 120 degrees apart from each other about a circular pattern circumscribed around the rhombus-shaped magnet and positioned on a circuit board.

12. The motor position sensor assembly of claim 11 wherein, within every 60 degree interval of the circular pattern, absolute value of a redundant signal that is not used for position estimation is greater than or equal to summation of absolute value of working signals.

13. The motor position sensor assembly of claim 9 further comprising a circular magnetic shield surrounding the rhombus-shaped magnet, the circular magnetic shield positioned on a circuit board holding the at least one magnetic flux density sensor.

14. The motor position sensor assembly of claim 9 further comprising a support surrounding an end of the shaft and for holding the rhombus-shaped magnet to the shaft.

15. The motor position sensor assembly of claim 14 wherein the support includes a cup shaped portion for holding the rhombus-shaped magnet, wherein the at least one magnetic flux density sensor is located exteriorly of the cup shaped portion.

16. The motor position sensor assembly of claim 9 wherein the at least one magnetic flux density sensor includes three Hall sensors A, B, and C positioned 120 degrees apart from each other about a circular pattern circumscribed around the rhombus-shaped magnet, and wherein rotor shaft position information is extracted by measuring output signals V from the Hall sensors A, B, C, and employing the following algorithm to determine position θ

at different intervals;

17. A position sensor assembly for detecting rotation of a rotating body, the rotating body having a longitudinal axis, the position sensor assembly comprising:

a magnet positioned coaxially with the longitudinal axis of the rotating body, wherein the magnet is rotatable with the rotating body;

a plurality of Hall sensors positioned at equal distances from a center of the magnet, wherein rotation of the magnet is detected by the plurality of Hall sensors; and

,

a support surrounding an end of the rotating body and for holding the magnet to the rotating body;

wherein the support includes a cup shaped portion for holding the magnet, wherein the Hall sensors are located exteriorly of the cup shaped portion.

18. The position sensor assembly of claim 17 further comprising a circular shield positioned exteriorly of the cup shaped portion and stationary with respect to rotation of the rotating body and magnet.

19. The position sensor assembly of claim 17 wherein the magnet is rhombus-shaped.

20. The position sensor assembly of claim 17 wherein the magnet is cylindrically shaped.

21. The position sensor assembly of claim 20 wherein the magnet is magnetized through its diameter.

22. The position sensor assembly of claim 20 wherein the cylindrically shaped magnet is ring-shaped with a central aperture.

23. The position sensor assembly of claim 20 wherein the cylindrically shaped magnet is imperforate.

24. The position sensor assembly of claim 20 comprising two Hall sensors positioned 90 degrees apart from each other.

25. The position sensor assembly of claim 24 wherein rotating body position is extracted using an algorithm as follows:

f(θ

,φ

)=A cos−

B sin φ


f′

(θ

,φ

)=−

A sin φ

−

B cos φ

where A and B are signals obtained from the Hall sensors, A=B_m sin θ and

B=B_m cos θ

, B_m is amplitude of signal, θ

is position in mechanical degrees, and φ

is an initial estimation of position angle, and

φ

_new=φ

_old−

f(θ

,φ

)/f′

(θ

,φ

).

26. The position sensor assembly of claim 25 wherein, when φ

converges within a tolerance, then φ

is an actual value of position θ

.

27. A position sensor assembly comprising:

a cylindrically shaped magnet;

two Hall effect sensors positioned 90 degrees apart from each other and positioned equidistantly from the magnet;

wherein position information is extracted using an algorithm as follows;

f(θ

,φ

)=A cos φ

−

B sin φ


f′

(θ

,φ

)=−

A sin φ

−

B cosφ

where A and B are signals obtained from the Hall sensors, A=B_m sin θ and

B=B_m cos θ

, B_m is amplitude of signal, θ

is position in mechanical degrees, and φ

is an initial estimation of position angle, and

φ

_new=φ

_old−

f(θ

φ

)/f′

(θ

,φ

).

28. The position sensor assembly of claim 27 wherein, when φ

converges within a tolerance, then φ

is an actual value of position θ

.

29. The position sensor assembly of claim 27 further comprising a circuit board positioned parallel with the magnet and holding the Hall effect sensors stationary with respect to the magnet.