Electric fan
The power output of the electric fan depends on the version:
- 400 Watts
- 600 Watts
- 850 Watts
- 1000 Watts
The electric fan is arranged behind the cooler. The Digital Engine Electronics (DME) activate the electric fan.
A new feature is that the power supply from terminal 30 via a relay comes from the Digital Engine Electronics (DME). The electric fan is controlled by the Digital Engine Electronics (DME) via a pulse-width-modulated signal (evaluation by electronic circuitry in the electronics of the electric fan). The Digital Engine Electronics (DME) control the various electric fan speeds by means of a pulse-width-modulated signal (between 7% and 93%). Pulse duty factors less than 7% and greater than 93% do not trigger activation but rather they are used for fault recognition purposes. The speed of the electric fan is dependent on the coolant temperature at the coolant outlet (radiator) and the pressure in the air conditioning system. When the car's driving speed increases, the speed of the electric fan decreases.
| Item | Explanation |
|---|---|
| 1 | Drive for electric fan |
| 2 | 4-pin plug connection |
| 3 | Fan cowl |
The drive of the electric fan is a brushless motor. The electric fan has its own electronic evaluation unit and its speed is regulated by a pulse-width modulated signal. The pulse duty factor in the normal operating mode (100 Hz) is converted into a speed signal.
- 7% pulse duty factor: Standby mode (electronic evaluation unit is kept awake)
- 11% pulse duty factor: minimum fan speed (33 % of rated speed)
- 93% pulse duty factor: maximum fan speed
- 97% pulse duty factor: command for self-diagnosis of the electronic evaluation unit.
For the after-run of the electric fan, the Digital Engine Electronics (DME) lower the frequency to 10 Hz. The pulse duty factor is used to select the time (maximum 11 minutes) and speed of the electric fan.
The permitted operating temperature lies between -20 °C and 120 °C. The static pressure lies between 0 and 0.8 bar.
The following illustration shows the air flow rate of the electric fan.
Example: characteristic curve depending on fan output
| Item | Explanation |
|---|---|
| 1 | Static pressure |
| 2 | Characteristic curve for flow rate |
| 3 | Volumetric flow |