Patent ID: 7566282

Claim:
A vehicle steering system, comprising: a device for changing gear ratio; an auxiliary electrical drive, said device for changing gear ratio containing a stator and said auxiliary electrical drive having a rotor and superimposing steering interventions of a driver over a steering wheel and transferring said steering interventions to steering motion of the vehicle wheels; a housing; a driving unit drivable by said steering wheel; a driven element connectable with the vehicle wheels, as well as at least two planetary gearings, including a first planetary gearing that is drivable by said rotor of an electric motor, and a second planetary gearing; a driving moment starting out from said steering wheel being superimposed with a driving moment of said electric motor and said two moments being initiated jointly as an output moment into said driven element, a ratio of rotational speed of said driving unit to rotational speed of said driven element being adjustable, each of said planetary gearing comprising a planetary gear train; said rotor being connected to a planet carrier of the planetary gear train of said first planetary gearing, one part of an internal gear wheel of said planetary gear train of said first planetary gearing being connected with said housing; a second part of said internal gear wheel of said planetary gear train of said first planetary gearing being connected to a first part of an internal gear wheel of the planetary gear train of said second planetary gearing; a driving shaft connected with a second part of said internal wheel of said planetary gear train of said second planetary gearing; planet wheel halves engaging parts of said internal gear wheel of said planetary gear train of said first planetary gearing being coupled non-rotationally with one another; a planet carrier of said planetary gear train of said second planetary gearing being switchably connectable with said driving unit connected with said steering wheel and said drive shaft.