Motor driven valve is provided with brushless servomotor with a rotor inside a magnetically transparent casing, and a stator which is located outside the casing and comprises drive coils and Hall effect units

摘要

The motor driven sealed valve unit (10) for control of liquid flow is provided with a brushless servomotor (40) incorporating a rotor (41) with permanent magnets (42) inside a magnetically transparent casing (44) and, outside the casing, a stator (48) with drive coils and Hall effect units. Also claimed is a method for operating the sealed motor. It involves supply of the drive coils with current pulses which are separated from one another by relatively long time intervals to minimize heat generation in the motor.