The Servotronic controls the power-assisted steering of the power steering depending on the speed by means of the Servotronic valve (electro-hydraulic converter). To do so, the flow of hydraulic oil of the power steering is throttled to varying degrees by the Servotronic solenoid valve.
Servotronic valve
The Servotronic valve is an electro-hydraulic converter located in the hydraulic oil circuit of the power steering. The valve has a variable shutter that throttles the oil flow to varying degrees depending on activation. The shutter diameter is varied by a speed-dependent flow characteristic curve
Control unit
The Servotronic function is integrated in the junction box electronics (JBE). The Junction Box electronics regulate the Servotronic valve. The characteristic curve for the speed-dependent activation of the Servotronic valve is stored as codable in a non-volatile memory.
The following messages or signals, among others, are required for the Servotronic function:
The system regulates the power-assisted steering on a speed-dependent basis. The Servotronic valve variably throttles the flow of hydraulic oil in the power steering. The degree of throttling depends on the current used to activate the valve.
The characteristic curve for the Servotronic valve specifies the current depending on the speed.
The characteristic curve is described by reference points, whereby the speed and current are coded for each reference point.
The Servotronic only activates the Servotronic valve if terminal 15 is on and the engine is running. As long as there is no speed signal at engine start-up, the maximum possible steering power assistance is set. When the correct travelling speed is received, the specified value is taken from the electrical characteristic curve.