Cooling System: Description and Operation

Coolant System Thermal Management







The cooling system is part of the thermal management system and has two circuits which can be regulated depending on the coolant temperature. In the Panamera, this is done by an electric, map-controlled and deactivatable thermostat.

The thermostat permits automatic, demand-based suppression of the coolant flow when the engine is cold (cold start). As a result, the engine heats up more quickly (Start Stop operating condition is reached more quickly) and friction, fuel consumption and pollutant emissions are reduced in the warm-up phase.

Depending on the increase in engine temperature, the coolant flow through the engine (small circuit) is then activated during warming up. After this, the coolant radiator is activated (large circuit) depending on the engine operating point and based on a map stored in the engine control. The map control of the thermostat then regulates the coolant temperature between 201 °F. (94 °C.) and 221 F. (105 °C.), depending on load, and therefore ensures optimum friction conditions in the engine that are adapted to the respective load point. This thermal management made it possible to reduce fuel consumption by up to 1.5%.







NEDC - New European Driving Cycle (yellow)
Pink - with thermal management
Light blue - without thermal management
°C - Coolant temperature
T - Time in seconds
km/h - Vehicle speed

Electrical activation of the coolant thermostat by the DME control unit benefits:
- Map-controlled coolant temperature regulation by suppressing coolant flow in the warm-up phase
- Engine heats up more quickly
- Reduced engine friction
- Lower fuel consumption
- -1.5% in the NEDC
- Reduced emissions

Temperature Sensors

Two temperature sensors are used for thermal management control.










Thermostat Opening

The main advantage of the map-controlled thermostat, which is electrically heated by the DME control unit, is that it is possible to regulate a specific temperature.







The thermostat is fully closed when the engine is cold.







Bypass Open - Electrical preheating makes it possible to quickly open the bypass for the small engine circuit in a controlled manner during the warm-up phase. This is achieved by providing more or less electrical heating close to the wax elements. The controlled bypass circulation in the small engine circuit allows the engine to reach operating temperature more quickly and in a uniform way.







Fully Open -The 2nd temperature sensor on the coolant hose permits early detection of when the thermostat starts to open and allows the necessary corrective action if necessary in order to achieve the setpoint temperature. The DME control unit adapts the opening behavior of the thermostat in order to compensate for tolerances and aging. The setpoint temperature in normal operation is 221 F. (105 °C.); the setpoint temperature is reduced to 201 °F (94 °C.) in Sport mode and in the event of certain faults.