Method and apparatus to convert an electrical value into a mechanical position by using an electromagnetic element subject to hysteresis

摘要

To eliminate the effect of hysteresis when electrical energy is supplied to an electromagnetic positioning element, for example to an electromagnetic valve, upon change in sign of the electrical energy which is provided from a previously occurring change, additional electrical energy is supplied if the change in energy is counter the direction of the magnetization curve. The extent of the additional energy may be at least as great as the gap between the ascending and descending branches of the hysteresis curves (H1, H2), or may be a quantity obtained by experience or measurement if the gap between the hysteresis curves is known or determinable. If the electromagnetic energy applied is in excess of that for reversal of magnetization, it may be applied for a period of time which is just long enough to permit remagnetization of a magnetic portion of the electromagnetic apparatus (11) but not long enough to cause change in a mechanical output thereof.