Actuator having an electric motor and an electromagnet arranged movably on the rotor of the electric motor to apply a holding torque with contact via a remanent magnetic field

Abstract

Various embodiments of the teachings herein include an actuator for a flap or for a valve for adjusting a gaseous or fluid volume flow. The actuator may include: a housing; an electric motor disposed in the housing; a downstream reduction gear; and a positioning element with an actuator connection for the flap or the valve. There is an electromagnet adjacent to an outer side of the rotor with a coil arrangement with a magnetic core. There is an electrical circuit arrangement for activating the electromagnet, providing a first brief current pulse, so a remanent magnetic field remains in the coil core. In a holding position of the actuator, while a mechanical pre-tensioning is set up, there is a holding torque with contact to the outer side of the rotor. The circuit arrangement provides a second brief current pulse to extinguish the remanent magnetic field still present in the coil core for releasing the holding torque with contact, forming an air gap between the electromagnet and the outer side of the rotor.