Method for controlling a valve element and valve assembly

摘要

A valve assembly HAS an element movable in a mechanical journal arrangement relative to a valve opening to establish an opening position of a valve, and A control unit for controlling the application of an oscillatory electromagnetic force to the element (8) having an known peak amplitude to cause the element to execute a sympathetic oscillatory motion as a friction reducing maneuver. The control unit is adapted to control the peak amplitude of the oscillatory electromagnetic force to sequentially apply a number of different peak amplitudes, each during a different measurement period. A monitor detects changes in the opening position of the valve during each of the measurement periods and provides a measure thereof. A processor is connected to the control unit and to the monitor to determine a working amplitude of the oscillatory electromagnetic force at which the detected changes will be minimized and to supply the determined working amplitude to the control unit.