Door drive device for adjusting a vehicle door relative to a vehicle body

A door drive device for moving a vehicle door relative to a vehicle body, having

• a motor;
• a transmission;
• a spindle rotatable about a longitudinal axis, wherein the motor is operatively connected to the spindle via the transmission and the spindle can be driven by the motor to rotate about the longitudinal axis;
• a spindle nut element which has a threaded connection to the spindle in such a way that by rotating the spindle the spindle nut element can be moved relative to the spindle along an adjustment direction oriented along the longitudinal axis;
• a guide rail for guiding the spindle nut element during movement along the adjustment direction;
• and, and,
• a push rod connected to the spindle nut element for transmitting an adjusting force between the vehicle door and the vehicle body, wherein the guide rail is formed in a sheet metal bending process and has a profile that is closed circumferentially around the adjustment direction.