SPS electrically controlled centering, function - GF46.50-P-2400AA

MODELS 203, 209, 211 with CODE (213a) Speed-sensitive power steering 

MODELS 215, 220, 230 

Function 

The electronic control system of the speed-sensitive power steering is integrated in the traction system control module (N47). A certain manual force (K) is set at the steering wheel according to the speed of the vehicle. As the speed of the vehicle increases, the manual effort (K) required to turn the steering increases at the steering wheel (up to 100 km/h).

The driving speed calculated by the traction system control module (N47) is assigned a nominal current in a characteristic map. This current is then set in the SPS solenoid valve (Y10) (proportional solenoid valve) and influences the oil flow (hydraulic reaction) within the rack-and-pinion steering, and thus the manual force (K) required at the steering wheel.

Fig 1: Manual Force Graph

The actuation of the SPS solenoid valve (Y10) is pulsed. The current is regulated by pulse-width modulation of these pulses.

Fig 2: SPS Solenoid Valve Pulse-Width Graph