Stationary magnet variable reluctance magnetic sensors

Abstract

A position sensor includes a rotor configured to be coupled to the rotatable element for rotation therewith, a non-rotationally mounted stator, a magnet non-rotationally disposed adjacent to the stator and spaced apart from the rotor, a first magnetic sensor non-rotationally mounted between the stator and the rotor, and a second magnetic sensor non-rotationally mounted between the stator and the rotor. The rotor is constructed at least partially of a magnetically permeable material and including a first rotor pole. The stator is spaced apart from the rotor and includes a first stator pole and a second stator pole, which are spaced radially apart from each other. The first magnetic sensor is disposed adjacent the first stator pole and radially offset from the second stator pole, and the second magnetic sensor is disposed adjacent the second main pole and radially offset from the first stator pole.

What is claimed is: 
     
         1 . A position sensor for sensing whether a rotatable element is in at least a first rotational position or a second rotational position, comprising:
 a rotor configured to be coupled to the rotatable element for rotation therewith, the rotor constructed at least partially of a magnetically permeable material and including a first rotor pole;   a non-rotationally mounted stator constructed at least partially of a magnetically permeable material, the stator spaced apart from the rotor and including a first stator pole and a second stator pole, the first stator pole and the second stator pole spaced radially apart from each other;   a magnet non-rotationally disposed adjacent to the stator and spaced apart from the rotor;   a first magnetic sensor non-rotationally mounted between the stator and the rotor, the first magnetic sensor disposed adjacent the first stator pole and radially offset from the second stator pole; and   a second magnetic sensor non-rotationally mounted between the stator and the rotor, the second magnetic sensor disposed adjacent the second stator pole and radially offset from the first stator pole.   
     
     
         2 . The position sensor of  claim 1 , further comprising a housing assembly that houses the rotor, stator, magnet, first magnetic sensor, and the second magnetic sensor. 
     
     
         3 . The position sensor of  claim 2 , wherein the housing assembly comprises:
 a first housing section having a first end, a second end, and a divider plate disposed between the first end and the second end to define a rotor cavity and a stator cavity within the first housing section; and   a second housing section coupled to the first housing section and having an inner surface that defines a second housing section cavity.   
     
     
         4 . The position sensor of  claim 3 , wherein:
 the rotor is disposed within the rotor cavity,   the first and second magnetic sensors are disposed within the stator cavity,   the magnet is coupled to the housing and is partially disposed within both the stator cavity and the second housing section cavity, and   the first stator pole is coupled to the stator and is partially disposed within both the stator cavity and the second housing section cavity.   
     
     
         5 . The position sensor of  claim 3 , further comprising:
 a sensor printed circuit board coupled between the first housing section and the second housing section, the sensor PCB having the first and second magnetic sensors coupled thereto.   
     
     
         6 . The position sensor of  claim 5 , further comprising:
 an electromagnetic interference shield disposed between the first magnetic sensor and the divider plate.   
     
     
         7 . The position sensor of  claim 1 , wherein:
 the rotor includes a second rotor pole that is diametrically opposed to the first rotor pole;   the stator includes a third stator pole and a fourth stator pole; and   the third stator pole and fourth stator pole are diametrically opposed to the first and second stator pole, respectively.   
     
     
         8 . The position sensor of  claim 7 , wherein:
 the stator further comprises a base, the base having the magnet disposed adjacent thereto; and   the first, second, third, and fourth stator poles extend perpendicularly from the base toward the rotor.   
     
     
         9 . The position sensor of  claim 7 , further comprising:
 a third magnetic sensor non-rotationally mounted between the stator and the rotor, the third magnetic sensor disposed adjacent the third stator pole and offset from the fourth stator pole.   
     
     
         10 . The position sensor of  claim 1 , wherein the first magnetic sensor is selected from the group consisting of a Hall sensor, an anisotropic magneto-resistive (AMR) sensor, a giant magneto-resistive (GMR) sensor, and a tunneling magneto-resistive (TMR) sensor. 
     
     
         11 . The position sensor of  claim 1 , wherein in the first rotational position, the first rotor pole, the first stator pole and the first magnetic sensor are aligned, and wherein in the second rotational position, the first rotor pole, the second stator pole and the second magnetic sensor are aligned. 
     
     
         12 . The position sensor of  claim 11 , wherein, in the second rotational position, the first rotor pole and the first magnetic sensor are out of alignment. 
     
     
         13 . A rotational sensor for sensing a rotational position or rotational speed of a rotatable element, comprising:
 a rotor configured to be coupled to the rotatable element for rotation therewith, the rotor constructed at least partially of a magnetically permeable material and including a first rotor pole;   a non-rotationally mounted stator constructed at least partially of a magnetically permeable material, the stator spaced apart from the rotor;   a magnetic sensor non-rotationally mounted between the rotor and the stator;   a first magnet coupled to the stator, wherein the first magnet has a first and second magnetic pole, wherein the first magnet has its first magnetic pole directed toward the stator and its second magnetic pole directed toward the rotor; and   a second magnet coupled to the stator and radially offset from the first magnet, wherein the second magnet has corresponding first and second magnetic poles, the second magnet having its second magnetic pole directed toward the stator and its first magnetic pole directed toward the rotor.   
     
     
         14 . The rotational sensor of  claim 13 , wherein the first magnetic pole of the first magnet is its north pole, and wherein the second magnetic pole of the first magnet is its south pole. 
     
     
         15 . The rotational sensor of  claim 14 , wherein the first magnetic pole of the second magnet is its north pole, and wherein the second magnetic pole of the second magnet is its south pole. 
     
     
         16 . The rotational sensor of  claim 13 , wherein the rotor includes a second rotor pole that is diametrically opposed to the first rotor pole. 
     
     
         17 . The rotational sensor of  claim 16 , wherein the sensor further comprises:
 a third magnet coupled to the stator and having its north magnetic pole directed toward the stator and its south magnetic pole directed toward the rotor, the third magnet diametrically opposed to the first magnet.   
     
     
         18 . The rotational sensor of  claim 17 , wherein the sensor further comprises:
 a fourth magnet coupled to the stator and radially offset from the third magnet, the fourth magnet having its south magnetic pole directed toward the stator and its north magnetic pole directed toward the rotor, the fourth magnet diametrically opposed to the second magnet.   
     
     
         19 . The rotational sensor of  claim 16 , wherein the magnetic sensor is selected from the group consisting of a Hall sensor, an anisotropic magneto-resistive (AMR) sensor, a giant magneto-resistive (GMR) sensor, and a tunneling magneto-resistive (TMR) sensor. 
     
     
         20 . The rotational sensor of  claim 13 , wherein in a first rotational position, the first rotor pole and the magnetic sensor are aligned, and wherein, in a second rotational position, the first rotor pole and the magnetic sensor are out of alignment.