Flux nulled wheel detector

Claim 2

The apparatus of claim 2 wherein said secondary coils are arranged to produce distinctive outputs associated with their position relative to the primary core as the ferro-magnetic object proceeds along the right of way and the output logic means is adapted to respond to the distinctive outputs for providing the directional information.

Claim 3

The apparatus of claim 3 wherein an oscillator provides the alternating current input signals and rectifier means coupled to the secondary coil outputs at opposite polarities provides the distinctive outputs for indicating directional information regarding the movement of the ferro-magnetic object along the right of way.

Claim 4

Apparatus for detecting the presence of a ferro-magnetic object along a right of way comprising: a. a primary core adjacent to the right of way; b. a primary coil wound on said primary core, said primary coil energized with a direct current input signal for generating a magnetic field and said primary coil wound on said primary core being positioned relative to the right of way so that a portion of the right of way is in the magnetic field generated from the primary coil; c. a secondary core positioned adjacent to said primary core and in the magnetic field generated from said primary coil across a portion of the right of way; d. a secondary coil wound on said secondary core, said secondary coil responsive to the magnetic field generated from said primary coil; e. said secondary coil aligned in the magnetic field generated from said primary coil such that a null or zero output exists across the secondary coil; f. a device biased fro carrying a direct current and located within said secondary coil responsive to a net flux therein for producing an output indicative of the ferro-magnetic object proceeding along the right of way and through the magnetic field; and g. output logic means connected to said secondary coil for detecting the signal change from the secondary coil as the ferro-magnetic object proceeding along the right of way interrupts and distorts the magnetic field generated from said primary coil.

Claim 5

The apparatus of claim 5 further including an additional secondary core with an additional secondary coil wound thereon and aligned adjacent to the primary core similarly as the first secondary core in the magnetic field generated from the primary coil across a portion of the right of way, a second device located within said additional secondary coil biased for carrying a direct current responsive to a net flux for providing an object presence signal; and said output logic means is connected to both secondary coils and is responsive to signal outputs of both devices for providing directional indication relative to movement of the ferro-magnetic object past the primary along the right of way.

Claim 6

The apparatus of claim 5 wherein said device is responsive for producing one polarity signal or another in accordance with the direction of said net flux.

Claim 7

The apparatus of claim 7 wherein said output logic means is responsive to the signal output of said device for producing directional indication of the movement of the ferro-magnetic object along the right of way through the magnetic field in accordance with the polarity of said device output.

Claim 8

The apparatus of claim 5 wherein said device comprises a Hall-Effect solid state semi-conductor.