Variable inductance transducer combined assembly and calibration method

摘要

A variable inductance transducer for providing, via inductance modulation, an electrical output signal which is representative of a mechanical input signal. In a preferred embodiment the mechanical input signal is the intake manifold vacuum of an internal combustion engine and the electrical output signal is utilized in an engine spark timing control system to adjust the spark timing in accordance with the intake manifold vacuum. The transducer comprises an actuating mechanism in the form of a vacuum servo which axially positions a ferrite core within a central axial bore of a plastic bobbin on which an inductive coil is wound to thereby vary the inductance of the coil in accordance with the vacuum applied to the servo. The bobbin and coil are enclosed in plastic to form a separate unit which is assembled into the transducer by being controllably lodged within the bore of a molded plastic element forming a portion of the body of the transducer. The transducer is calibrated by the controlled lodging of the unit within the bore of the molded plastic element.