Speed sensor

A speed sensor for sensing speed of a toothed ferromagnetic reluctor member comprising in combination with said reluctor member an electromagnetic pick-up device disposed in relation to said reluctor member such that teeth of said reluctor member move past said device upon movement of said reluctor member relative to said device, said pick-up device comprising:

• a magnetic flux source creating a magnetic circuit extending from said device through said reluctor member and returning to said device;
• a toroidal ferromagnetic core member disposed in said magnetic circuit;
• an inductance coil inductively disposed on said toroidal ferromagnetic coil member;
• and a capacitor electrically connected across said inductance coil.

In combination:

• a non-ferromagnetic casing;
• a rotary ferromagnetic reluctor member within said casing providing a variable reluctance;
• an electromagnetic pick-up device comprising a housing disposed on the outside of said casing in juxtaposition to said reluctor member such that the device is magnetically coupled with said reluctor member;
• said housing comprising a mounting tab having an opening therein;
• said casing having an integral projecting stud on the outside thereof extending through said opening;
• and a fastener on said stud over said tab.

A speed pick-up device adapted for use with a movable toothed ferromagnetic reluctor member for sensing speed thereof, said pick-up device comprising:

• a housing;
• a toroidal ferromagnetic core member disposed within said housing;
• an inductance coil inductively disposed on said toroidal core member within said housing;
• a magnetic flux source disposed within said housing;
• a capacitor disposed within said housing and electrically connected across said inductance coil;
• said magnetic flux source, said toroidal ferromagnetic core member and said inductance coil being arranged within said housing to form a magnetic circuit which when said pick-up device is used with a movable toothed ferromagnetic reluctor member has the circuit reluctance varied by movement of said ferromagnetic reluctor member whereby the resonant frequency of said inductance coil and said capacitor is modulated;
• and means via which said inductance coil and said capacitor may be connected in an electrical circuit which is located exteriorly of said housing.