Measuring procedure
The oil condition sensor consists of 2 cylindrical condensers. The condensers are mounted above one another. 2 metal tubes are inserted one into the other to serve as electrodes. The engine oil is used as a dielectric medium between the electrodes.
A dielectric is defined as a non-conductive material in an electrical field. An insulator penetrates the electrical field. Permittivity (lat.: permittere = permit, let through) is also referred to as the dielectric conductance. The permittivity specifies the degree to which materials allow electrical fields to pass. The factor indicates by how much the voltage at a capacitor drops when a dielectric, non-conducting material is arranged between the capacitor plates.
| Item | Explanation |
|---|---|
| 1 | Range for measurement of the oil level |
| 2 | Range for measurement of permittivity |
| 3 | Inner capacitor |
| 4 | Dielectric (engine oil) |
| 5 | Outer capacitor |
| 6 | Housing |
| 7 | Temperature sensor |
| 8 | Evaluation electronics |
| 9 | Oil sump |
The temperature sensor is seated on the housing of the oil condition sensor. The housing of the oil condition sensor contains an electronic evaluation unit. The electronic evaluation unit has self-diagnosis. A fault in the oil condition sensor is entered in the fault memory of the engine control system.
The oil condition sensor sends its measured values to the engine control system:
- Engine oil temperature
- Oil level
- Engine oil quality
The electrical material properties of the engine oil change as the engine oil wears and ages. The changed electrical properties of the engine oil (dielectrics) cause the capacity of the capacitor to change.
The electronic evaluation unit converts the measured capacity into a digital signal. The digital sensor signal is sent to the engine control system. The engine control system uses the signal for internal calculations (e.g. condensate in the engine oil).