US 5,444,369 A · Magnetic rotational position sensor with improved output linearity

Abstract

A rotary shaft position sensor includes a stator and a rotor and produces a linear output signal in accordance with the rotational position of a shaft coupled to the rotor. The rotor rotates about an axis of rotation. The stator includes stationary pole pieces having stationary pole faces situated perpendicular to the axis of rotation and spaced a predetermined distance apart to define an air gap therebetween. A Hall effect device is situated-in the air gap. The Hall device produces an output signal corresponding to the level of magnetic flux in the air gap. One or more magnets are attached to the rotating pole piece. The magnetic poles of the magnets are situated parallel with and spaced a predetermined distance from the stationary pole faces. Lines of magnetic flux originating from the magnets are situated in a direction perpendicular to the stationary pole face. The rotating pole piece rotates in close proximity to the stationary pole pieces. As the rotor rotates about the axis of rotation, a portion of the magnet is aligned with the stationary pole faces. Magnetic flux corresponding to the aligned portion of the magnet and the stator pole faces appears in the air gap. A temperature compensation circuit for use with the rotary shaft position sensor includes first and second temperature compensation circuits for counteracting sensitivity temperature drift and zero gauss offset temperature drift characteristics of the Hall effect device.

Claims24

Dependent claims

A magnetic rotational position sensor for sensing angular position of an object about a rotational axis, comprising:

a magnetic flux sensor operative to produce an output signal corresponding to a sensed level of magnetic flux;
magnetic means for producing magnetic flux;
means for conducting magnetic flux between said magnetic means and said magnetic flux sensor including stationary means for conducting said magnetic flux across a stationary surface perpendicular to said axis of rotation and rotating means for conducting magnetic flux across a rotating surface perpendicular to said axis of rotation, said stationary surface being spaced a predetermined distance from said rotating surface to define an air gap therebetween;
said magnetic means producing said magnetic flux parallel to said axis of rotation and perpendicular to said stationary surface and said rotating surface;
and
wherein said rotating means rotates relative to said stationary means to align a portion of said rotating surface with a portion of said stationary surface to conduct a level of magnetic flux proportional to the amount of surface area alignment of said portion of said stationary surface and said portion of said rotating surface, said level of magnetic flux being conducted between said magnetic means and said magnetic flux sensor and across said predetermined air gap to complete a magnetic circuit.

3 more elements

A magnetic rotational position sensor for sensing angular position of an object, comprising:

first and second stationary pole pieces having first and second stationary pole faces, respectively, said first and second stationary pole pieces being spaced a first predetermined distance apart to define a first predetermined air gap therebetween;
a magnetic flux sensor situated in said first predetermined air gap, said magnetic flux sensor producing an output signal corresponding to a level of magnetic flux in said first predetermined air gap;
a rotating pole piece, said rotating pole piece defining an axis of rotation for said magnetic rotational position sensor;
a first magnet having a first magnet pole face, said first magnet generating magnetic flux in a direction parallel to said axis of rotation and being attached to said rotating pole piece with said first magnet pole face spaced a second predetermined distance from said first and second stationary pole faces to define a second predetermined air gap;
and
wherein said rotating pole piece rotates relative to said first and second stationary pole pieces about said axis of rotation to align a portion of said first magnet pole face with portions of said first and second stationary pole faces and supply a level of magnetic flux corresponding to the aligned portions of said first magnet pole face and said first and second stationary pole faces into said first predetermined air gap.

3 more elements

Dependencies are inferred from the claim text.

Magnetic rotational position sensor with improved output linearity

Life of this patent

Magnetic rotational position sensor with improved output linearity

Life of this patent

Abstract

Claims24