Sensor System Including a Magnetized Shaft

• US 20090165571A1
• Filed: 12/29/2008
• Published: 07/02/2009
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Stoneridge Control Devices, Inc. (Stoneridge Incorporated)
• Original Assignee: Stoneridge Control Devices, Inc. (Stoneridge Incorporated)
• Inventors: Hedayat, Kayvan, Poirier, Norman
• Granted Patent: US 7,895,906 B2
• Time in Patent Office: Days
• US Class Current: 73/862.333
• CPC Class Codes: G01L 3/102 involving magnetostrictive means magnetostrictive sensors H10N35/101
• CPC Class Codes: G01L 3/104 involving permanent magnets

Abstract

A sensor includes a shaft and a magnetic sensor. The shaft may have at least one magnetized active region. The magnetic sensor may be configured to sense a magnetic field about the shaft, and may provide an output representative of torque applied to the shaft, shaft rotational speed and shaft rotational position.

Claims

1. A sensor comprising:

a shaft having at least one active region, said at least one active region having an elliptical magnetization; and

at least one magnetic sensor configured to sense a magnetic field about said shaft, said magnetic field being representative of a torque applied to said shaft.

2. The sensor of claim 1, wherein said elliptical magnetization has a nonzero axial component directed along a center line axis of said shaft at zero torque applied to said shaft, and wherein said magnetic sensor is configured to sense said nonzero axial component at zero torque.

3. The sensor of claim 1, wherein said elliptical magnetization is induced by current driven between a pair of electrode clamps, said pair of electrode clamps oriented at an oblique angle with respect to a center line axis of said shaft, wherein said elliptical magnetization has a nonzero axial component along a center line axis of said shaft at zero torque, and wherein said nonzero axial component at zero torque is at least partially dependent on a value of said oblique angle.

4. The sensor of claim 1, wherein said elliptical magnetization has a nonzero axial component along a center line axis of said shaft at zero torque, and wherein nonzero axial component changes as said torque is applied to said shaft.

5. The sensor of claim 1, wherein said magnetic field sensed by said magnetic sensor comprises alternating magnetic polarities as said shaft is rotated and said magnetic sensor provides a sinusoidal signal having an amplitude representative of said torque applied to said shaft.

6. The sensor of claim 5, wherein a frequency of said sinusoidal signal is representative of a speed of said shaft.