Functional description
Input variables for the calculation by means of the engine control are the following:
- Engine speed
- Load
- Driving speed
- Intake air temperature
- Coolant temperature
Based on the input variables listed, the engine control calculates the optimum coolant temperature for every operating point. The coolant temperature is influenced by specific heating of the wax element in the characteristic map thermostat as well as requirement-oriented activation of the electric fan. At full load, low coolant temperatures improves the cylinder filling. Moreover, the risk of knocking is reduced when the engine temperature is lower. This can be a positive influence on the power output and torque.
| Item | Explanation |
|---|---|
| 1 | Characteristic map thermostat |
| 2 | two-pin plug connection |
| 3 | Coolant temperature sensor |
| 4 | Coolant pump |
The wax element of the characteristic map thermostat contains a heating resistor. The engine control supplies the heating resistor with current. This causes the wax element to expand and close the cylinder head inlet against the spring pressure of a spring. The spring has the task of pressing the characteristic map thermostat back into its rest position when the wax element cools down. When the engine is cold, the coolant circuit runs via the cylinder head inlet and the characteristic map thermostat to the return line towards the coolant pump.