Water Pump - Hybrid Drive: Description and Operation

Pump for charge-air cooling (G)

The charge-air cooling pump is an electrically powered coolant pump. The pump conveys the heated coolant from the charge-air intercoolers in the air-charging module to the low-temperature cooler. This cooler is installed in the cooling module in the vehicle engine compartment (in front of the main cooler viewed in the direction of travel). The pump is installed at the front left of the engine compartment near the oil cooler. The pump is designed based on a centrifugal pump.

A centrifugal pump is not self-aspirating and should therefore not be allowed to run dry because the pump bearings may overheat. The following assemblies are integrated in the pump module:
- Centrifugal pump
- Electric motor
- Electronic control

Function of the pump control







The pump is activated depending on the temperature from a map in the engine control module downstream of the charge-air cooler and the pressure downstream of the charge-air cooler. It always runs from 1,300 mbar or from a coolant temperature of 122° F. (50° C). The pump is controlled by the engine control unit via a PWM signal. The pump electronics use this signal to calculate the required pump speed and control the electric motor. If the pump is working correctly, the pump electronics send the current pump speed back to the engine control module. This process runs cyclically throughout pump operation.