Variable inductance transducers

摘要

A variable inductance transducer for providing, via inductance modulation, an electrical output signal which is representative of a mechanical input signal. The transducer comprises a cylindrical plastic bobbin on which an inductive coil is wound. A pair of electrical terminal receiving sockets for a pair of electrical terminals are formed at one end of the bobbin and a pair of electrical terminals are disposed therein. The ends of the wire forming the coil are soldered to the terminals. A protective enclosure is molded around the coil and the portions of the terminals received in the sockets to enclose the coil and lock the terminals in place in the sockets. A ferrite core is slidably arranged within a central axial bore in the bobbin to vary the inductance of the transducer in accordance with the axial position of the core. The core is selectively positioned by means of an actuating mechanism including a flexible actuating member and in one disclosed embodiment the actuating mechanism is a vacuum servo while in another disclosed embodiment, it is a formed wire rod. The transducer is of reasonable cost and possesses accuracy, repeatability and response which makes its usage in an engine spark timing control system significantly advantageous.