Pickupless magnetostrictive position measurement apparatus

A magnetostrictive measurement apparatus comprising:

• a circuit including a magnetostrictive wire having first and second opposed ends, the circuit transmitting an electrical excitation pulse and detecting a return signal therefrom indicative of the position of a magnet means along the magnetostrictive wire;
• a first magnet displaceable relative to the magnetostrictive wire, the first magnet interacting with the electrical excitation pulse and generating first and second oppositely propagating torsional waves in the magnetostrictive wire;
• a second magnet fixedly positioned relative to the magnetostrictive wire and interacting with the electrical excitation pulse and generating third and fourth oppositely propagating torsional waves in the magnetostrictive wire;
• and wherein
• one of the first and second torsional waves and one of the third and fourth torsional waves generated by the first and second magnets, respectively, propagating on the magnetostrictive wire to the other of the first and second magnets and interacting with the magnetic field of the other of the first and second magnets to generate separate electrical currents in the magnetostrictive wire, the separate electrical currents being additive and forming the return signal.

A method of determining the position of a magnet along a length of wire comprising the steps of:

• forming a circuit including a magnetostrictive wire having first and second ends;
• exciting the circuit with an electrical excitation pulse;
• movably disposing a first magnet relative to the magnetostrictive wire;
• generating first and second oppositely directed torsional waves at the position of the magnet through the interaction of the magnetic field of the magnet and the magnetic field associated with the electrical excitation pulse;
• reflecting the second torsional wave in the magnetostrictive wire generated by the electrical excitation pulse from the second end of the wire to the first magnet wherein the magnetic field of the first magnet means interacts with the second torsional wave to induce electrical current in the magnetostrictive wire;
• and
• determining the position of the magnet along the magnetostrictive wire based on the time differential between the transmission of the electrical excitation pulse on the circuit and the detection of the electrical current in the circuit.

A method of wherein the step of propagation a torsional wave determining the position of a magnet along a length of wire comprising the steps of:

• forming a circuit including a magnetostrictive wire having first and second ends;
• excitind the circuit with an electrical excitation pulse;
• movably disposing a first magnet relative to the magnetostrictive wire;
• generating first and second oppositely directed torsional waves at the position of the magnet through the interaction of the magnetic field of the magnet and the magnetic field associated with the electrical excitation pulse;
• mounting a second magnet in a fixed reference position about the magnetostrictive wire;
• generating third and fourth oppositely directed torsional waves propagating along the magnetostrictive wire by the interaction of the electrical excitation pulse and the magnetic field of the second magnet;
• and
• generating a first electrical current in the circuit through the interaction of the second torsional wave and the second magnet and a second electrical current in the circuit through the interaction of the fourth torsional wave and the first magnet.