Pump motor control
The control module activates the output to the hydraulic pump as soon as the following conditions are fulfilled: "ignition ON" and "engine started". The output is active until the calculated pressure is approx. 32 bar. The pressure is calculated by means of the control module measuring electric motor power consumption. The higher the pressure, the greater the resistance there is for the electric motor to drive the pump itself, and the higher the current becomes. When the pressure in the system amounts to approx. 32 bar (fully charged accumulator) the accumulator piston exposes the unloading holes and the pressure does not increase further.
The current to the motor does not increase any further but remains constant, the control module now knows that full system pressure has been reached and shuts down the pump. Restart takes place when the calculated pressure is below approx. 27 bar.