Transporting system of floated-carrier type

Abstract

A transporting system of floated carrier type including a guide rail having a bottom surface portion formed of a ferromagnetic material, a carrier arranged to be freely movable along the guide rail, at least one magnetic supporting unit placed on board the carrier and including electromagnets arranged so as to face the bottom surface portion of the guide rail via gap and a permanent magnet that is placed in the magnetic circuit formed by the electromagnets, the guide rail, and the gap, for supplying magnetomotive force required for floating the carrier. A sensor section is attached to the carrier for detecting changes in the magnetic circuit. The length of the gap is controlled by a zero power feedback loop that stabilizes the magnetic circuit in a state in which the current flowing in the electromagnets is zero, by controlling the exciting current in the electromagnets based on the output of the sensor section. However, the zero power feedback loop is actuated only when the gap length between the electromagnets and the guide rail is within a predetermined range. With this construction, it becomes possible to realize reduced power consumption as well as reduction in size of the system.