Servotronic

Servotronic refers to a speed-dependent control of the power steering. Under this name, it is used in vehicles from the Audi , BMW , Škoda Auto and Volkswagen brands . There are several derivatives of the Servotronic. In contrast to Servotronic, conventional power steering is based on the engine speed. The term Servotronic is a case word from the terms power steering and electronics .

General

The Servotronic is an electronically controlled hydraulic steering in which the hydraulic support forces are only influenced by the driving speed. The lower the speed , the more steering assistance is made available. This makes maneuvering easier when entering and leaving a parking space. The higher the speed, the less steering assistance is available, which leads to more direct steering . This enables the driver to keep the vehicle more safely in the lane, even at high speed, without too direct steering intervention causing the vehicle to skid.

Components

• Electronic speedometer
• Control unit
• electro-hydraulic converter
• Power steering
• Pressure oil pump
• oilcontainer

Mode of action

At speeds below 20 km / h, the solenoid valve influenced by the control unit remains closed. Is z. B. if the steering spindle is turned clockwise when turning to the right, the right valve piston is pushed down. The pressurized oil flows into the right working space as well as through the check valve into the left working space and through both throttles. The same pressures prevail in both rooms, which is why a pressure acting torque is created on the torsion bar, and the support pressure becomes effective. The steering wheel can be turned more easily.

When driving at high speed, the solenoid valve is fully opened, pressure accumulates in the right-hand room, while the left-hand room remains without pressure; as a result, the valve pistons are turned back into the neutral position and no support pressure can be built up for the steering.

source

• Technical information service - BMW, status 2006