Saturable core proximity sensor including a flux director and a magnetic target element

A saturable core distance sensor comprising:

• a target magnet that generates a magnetic field having X, Y, and Z directional components, said X directional component having a predetermined flux density;
• a base plate made of a permeable material that is positioned adjacent the target magnet to substantially eliminate said Y and Z directional components of the magnetic field;
• sensor means for detecting said X directional component of the magnetic field that includes:
• a core having a distal end and a proximal end and a longitudinal axis that is aligned substantially parallel with the X directional component of the magnetic field, wherein said core has a cross-sectional area in a plane perpendicular to the longitudinal axis that is substantially smaller than a cross-sectional area of the core along the longitudinal axis, said core becoming magnetically saturated when exposed to the X directional component of the magnetic field, but not saturating when exposed to magnetic fields having the predetermined flux density that extend in a direction substantially deviating from the X direction;
• an inductive element surrounding said core that produces a second magnetic field that flows through the core and through an air gap that exists between the distal and proximal ends of the core, said inductive element providing an output signal that varies as a function of the distance between said target magnet and said sensor means within a predetermined range;
• and
• a flux director disposed at the distal end of the core for intercepting a fringing portion of the X directional component of the magnetic field produced by the target magnet and for directing the fringing portion of the magnetic field through the core.

A sensor for use with a target magnet that provides a magnetic field having X, Y, and Z directional components, the sensor comprising:

• an elongate core having a longitudinal axis, and a plurality of arms disposed at a distal end of the core that direct a fringing portion of the magnetic field through the core;
• an inductive element surrounding said core, said element having a magnetic field associated therewith when coupled with a source that provides a predetermined drive current;
• wherein the configuration of said core and the material from which said core is made are selected so that when said longitudinal axis of said core extends parallel to the X directional components and said core is positioned within a predetermined proximity of the target
• (a) said core provides
• (i) a sufficiently high reluctance path to the Y and Z directional components of the magnetic field of the target so as to substantially prevent the Y and Z components from entering said core, and
• (ii) a sufficiently low reluctance path to the X directional components of the magnetic field of the target so that the X directional components will enter said arms of said core, and
• (b) said X directional components together with the magnetic field of said inductive element cause said arms and said core to magnetically saturate to a predetermined value.