Position sensor and assembly

• US 7,474,090 B2
• Filed: 10/23/2007
• Issued: 01/06/2009
• Est. Priority Date: 10/22/2004
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations Incorporated (General Motors Company), Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Mielke, Matthew, Sebastian, Tomy, Islam, Mohammad S.
• Primary Examiner(s): WHITTINGTON, KENNETH
• Application Number:
  US11/877,291
• Publication Number:
  US 20080048650A1
• Time in Patent Office: 441 Days
• Field of Search: 324/207.11, 324/207.2, 324/207.21, 324/207.22, 324/207.23, 324/207.25, 324/244, 324/247, 324/252
• US Class Current: 324/207.25
• 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

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,

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;

2. The position sensor assembly of claim 1 wherein, within every 60 degree interval of the circular pattern, an absolute value of a redundant signal from one of the three Hall sensors that is not used for position estimation is greater than or equal to a summation of an absolute value of working signals Hall sensors that are used for position measurement.

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. 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,

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;

8. The motor position sensor assembly of claim 7 wherein the rhombus-shaped magnet is magnetized through its major axis.

9. The motor position sensor assembly of claim 7 wherein, within every 60 degree interval of the circular pattern, an absolute value of a redundant signal from one of the three Hall sensors that is not used for position estimation is greater than or equal to a summation of an absolute value of working signals Hall sensors that are used for position measurement.

10. The motor position sensor assembly of claim 7 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.

11. The motor position sensor assembly of claim 7 further comprising a support surrounding an end of the shaft and for holding the rhombus-shaped magnet to the shaft.

12. The motor position sensor assembly of claim 11 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.