US Patent 9649904 Stroke sensor and fluid spring with stroke sensor

A stroke sensor detects a distance between a first member and a second member provided movably toward and away from the first member. The stroke sensor includes a magnetism generator provided in the first member and configured to generate magnetism, a magnetic body provided in the second member and configured to be biased toward the magnetism generator by a magnetic force generated from the magnetism generator, and a pressure detector provided in the second member, held in contact with the magnetic body biased by the magnetic force from the magnetism generator and configured to detect the distance between the first and second members on the basis of a change of a pressure acting from the magnetic body.