A
-
Pump speed (in rev/min)
B
-
Steer angle rate (in degrees/second)
The electrohydraulic power steering system uses an electrically-driven hydraulic pump and a conventional rack and pinion steering system. This ensures precise steering operation and steering assistance with minimum energy consumption.
Under continuous monitoring of the turning speed of the steering wheel with the aid of the integrated steering angle sensor, and under evaluation of the vehicle speed input signal, the control module uses a map to adjust the rate of the pump.
Steering gear
NOTE:The steering angle rotor is incorporated into the valve body of the steering gear and cannot be re-used.
Installed above the steering valve, the steering angle sensor forms an integral part of the rack and pinion steering system.
The steering angle sensor is a inductive sensor.
The steering angle sensor monitors the speed with which the steering wheel is being turned. This information is sent to the control module.
Brushless direct current motor
In the electrohydraulic power steering system, a brushless 12 volt direct current motor drives the hydraulic pump. Higher pumping rates are only provided when they are required for steering manoeuvres. This avoids unnecessary energy consumption in the majority of phases in a drive cycle.
Commutation in the motor is done electronically. As a result, there are no brushes to wear away. The entire system is designed for maintenance-free operation.
In more than 85% of all driving situations, the power steering pump operates at standby speed and consumes less than 4A. However, pump speed can quickly increase to full rotational speed if emergency steering manoeuvres require it.
The system has a continuously variable pump rotational speed.
Power steering pump
NOTE:The power steering pump must be filled and vented as specified.
The power steering pump comprises an electric motor, the hydraulic pump and the reservoir for the power steering fluid.
Using a brushless motor increases reliability and prolongs service life.
The hydraulic pump is a gear pump; a resonance chamber incorporated into the pump body reduces noise emissions.
A pressure limiting valve built into the pump housing limits the hydraulic fluid pressure to a maximum of approx. 120 bar.
There is no service interval specified for the power steering fluid.
