Adjustable steering column having at least one MRF actuator

A method for controlling an adjustable steering column of a motor vehicle, the adjustable steering column comprising a steering spindle that is surrounded by a casing tube and is connected to a steering wheel, a guide clamp in which the casing tube is guided displaceably along a longitudinal axis of the steering spindle, wherein the guide clamp is mounted pivotably about a pivot axis in a holding part that is connectable to a chassis of the motor vehicle, wherein a position of the casing tube is adjustable relative to the holding part, wherein a blocking device is disposed between the casing tube and the holding part, the blocking device comprising a threaded rod that is engaged with a spindle nut, wherein the blocking device is switchable between a fixing position and a release position, wherein in the fixing position adjustment of the steering column is blocked and in the release position adjustment of the steering column is unblocked, the method comprising:

• providing a rolling bearing that supports the spindle nut, wherein rolling bodies of the rolling bearing are at least partially surrounded by magnetorheological fluid;
• while switching the blocking device into the fixing position, magnetizing the rolling bodies by way of an electromagnet to increase a viscosity of the magnetorheological fluid such that rotation of the spindle nut is blocked;
• and
• while switching the blocking device into the release position, demagnetizing the rolling bodies by way of the electromagnet to reduce the viscosity of the magnetorheological fluid such that rotation of the spindle nut is unblocked.