Self-induction-type stroke sensor

摘要

A sensor member (4) has one end supported in a cantilever fashion adjacent a predetermined end of a body (2) and has the other end extending into a space of the body, and includes a plurality of coil segments (LA - LB) that are excitable in a same phase by a predetermined A.C. signal and sequentially arranged along a direction of movement of a movable member (3). The movable member (3) has an inner space (5) to permit entry of the sensor member (4) into the movable member (3). Inner peripheral wall of the movable member defining the inner space includes a magnetism-responsive substance (11). Relative positions of the magnetism-responsive substance (11) and the coil segments (LA - LB) vary with a stroke position of the movable member (3), in response to which respective inductance of the coil segments are caused to vary in such a manner that during movement of the magnetism-responsive substance (11) from one end to the other of a particular one of the coil segments, a voltage across the particular coil segment is caused to progressively decrease or increase.